US20060046618A1 - Methods and systems for determining physical parameters of features on microfeature workpieces - Google Patents

Methods and systems for determining physical parameters of features on microfeature workpieces Download PDF

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Publication number
US20060046618A1
US20060046618A1 US10/930,307 US93030704A US2006046618A1 US 20060046618 A1 US20060046618 A1 US 20060046618A1 US 93030704 A US93030704 A US 93030704A US 2006046618 A1 US2006046618 A1 US 2006046618A1
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workpiece
selected area
probe beam
feature
microfeature
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US10/930,307
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Gurtej Sandhu
Cem Basceri
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Micron Technology Inc
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Individual
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Assigned to MICRON TECHNOLOGY, INC. reassignment MICRON TECHNOLOGY, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SANDHU, GURTEJ S., BASCERI, CEM
Publication of US20060046618A1 publication Critical patent/US20060046618A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/005—Control means for lapping machines or devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
    • B24B49/12—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation involving optical means

Definitions

  • the present invention relates to methods and systems for determining physical parameters of features on microfeature workpieces. More particularly, the invention is directed to methods and systems for measuring dimensions, changes in dimensions, planarity, and/or changes in planarity of features on workpieces.
  • Deposition, photolithography, etching, and doping are some of the primary processes used in the manufacture of microelectronic devices (e.g., dies) on semiconductor wafers.
  • Microelectronic devices typically include submicron features formed on the wafer with precise dimensions. Errors in process steps can cause many problems including defective microelectronic devices. As such, the efficacy of the manufacturing processes must be qualified to ensure that the devices do not have defects and to determine whether anomalies are occurring in the processes. For example, after depositing a layer of material onto the wafer, the thickness of the layer can be measured to ensure that it is within the specification.
  • Metrology tools are used to measure various parameters of the wafer at different times during the production process and to ensure that the features formed on the wafer are within specification.
  • One conventional metrology tool includes a laser that directs a small laser beam toward discrete points on the surface of the wafer to measure the distance between the laser and the surface at the individual points. For example, after removing material from the wafer via chemical-mechanical planarization (“CMP”), the planarity of the wafer surface should be checked because CMP processing may remove material from the perimeter region of the wafer at a different rate than from the center region of the wafer.
  • CMP chemical-mechanical planarization
  • the edge uniformity of the wafer conventional metrology tools or other types of optoelectronic tools typically measure the distance between the wafer and the laser at 9 to 13 discrete points around the wafer perimeter. Based on the measurements at these different points, the tool estimates the edge uniformity of the wafer. Conventional systems similarly estimate the planarity of the surface by measuring the distance between the laser and the wafer at 30 to 50 discrete points across the wafer. Although these approaches are useful, the wafer surface may vary between the measured points and, accordingly, the results may not be accurate.
  • metrology tools may estimate the thickness or change in thickness of a film by measuring the distance between the wafer and the laser at 30 to 50 discrete points before and after the film is deposited, etched or planarized. The difference between the before and after measurements corresponds to the thickness of the film or the change in film thickness.
  • One problem with measuring 30 to 50 points before and after processing the wafer is that it is time consuming and reduces throughput. Moreover, the measurements may not provide an accurate representation of the film thickness because of variances across the wafer. Accordingly, there is a need for a fast and accurate process to determine physical features on the wafer.
  • FIG. 1 is a schematic isometric view of a system for measuring a physical parameter of a feature on a microfeature workpiece in accordance with one embodiment of the invention.
  • FIG. 2 schematically illustrates a process for scanning the workpiece in accordance with another embodiment of the invention.
  • FIG. 3 is a schematic side cross-sectional view of the system with an apparatus for measuring a depth of a feature on a workpiece.
  • FIG. 4 is a schematic side cross-sectional view of a system for determining a change in the thickness of a feature on a workpiece in accordance with another embodiment of the invention.
  • FIG. 5 is a schematic view of a system for polishing a microfeature workpiece in accordance with another embodiment of the invention.
  • a method includes directing a substantially coherent probe beam at a selected area having a plurality of regions on the microfeature workpiece to produce a reflected probe beam having phase information of the individual regions within the selected area.
  • the selected area can be only a portion of the workpiece.
  • the method further includes determining a physical parameter of one or more features at the individual regions within the selected area of the workpiece based on the reflected probe beam.
  • the physical parameter can be a depth, height, thickness, width, or other dimension of a layer, trench, hole, projection, or other feature on the workpiece.
  • a method in another embodiment, includes directing a substantially coherent probe beam toward a selected area of a feature on the microfeature workpiece to produce a first reflected probe beam having phase information of different points within the selected area. The method further includes processing the selected area of the workpiece, impinging the substantially coherent probe beam upon the selected area of the feature to generate a second reflected probe beam having phase information of different points within the selected area, and determining a change in a physical parameter of the feature in the selected area based on the first and second reflected probe beams. Processing the workpiece includes depositing material onto the workpiece and/or removing material from the workpiece.
  • a method includes pressing a microfeature workpiece against a polishing pad, moving the workpiece relative to the polishing pad, and directing a substantially coherent probe beam at a selected area of a feature on the workpiece to produce a reflected probe beam having phase information of different points within the selected area.
  • the method further includes determining a physical parameter of the feature at the different points within the selected area of the workpiece based on the reflected probe beam, and adjusting at least one polishing parameter in response to the determined physical parameter of the feature.
  • a system includes a radiation source for producing a substantially coherent probe beam, a sensing device for receiving a reflected probe beam and generating electrical signals based on the reflected probe beam, a workpiece support for positioning the microfeature workpiece in a path of the probe beam, and a controller.
  • the controller has a computer-readable medium containing instructions to perform any one of the above-mentioned methods.
  • microfeature workpiece is used throughout to include substrates in and/or on which microelectronic devices, micromechanical devices, data storage elements, and other features are fabricated.
  • microfeature workpieces can be semiconductor wafers, glass substrates, insulated substrates, or many other types of substrates.
  • FIG. 1 is a schematic isometric view of a system 100 for measuring a physical parameter of a feature on a microfeature workpiece 140 in accordance with one embodiment of the invention.
  • the system 100 can measure the depth, thickness, and/or other dimensions or changes in a dimension of a feature on the workpiece 140 . This is particularly useful in (a) qualifying workpieces after processing steps to ensure the workpieces are within specification, and (b) providing feedback to processing machines for modifying processing parameters to produce workpieces within specification.
  • the illustrated system 100 includes a measuring apparatus 110 for directing a coherent optical probe beam 118 along a beam path, a workpiece support 160 for positioning the workpiece 140 in the beam path, and a controller 170 (shown schematically) for operating the measuring apparatus 110 and/or the workpiece support 160 .
  • the measuring apparatus 110 includes a radiation source 112 (shown schematically) for producing the coherent probe beam 118 , an optical element 113 (shown schematically) for directing the coherent probe beam 118 toward a selected area 142 of the workpiece 140 , and a sensing device 114 for receiving a reflected probe beam.
  • the radiation source 112 can be a laser
  • the optical element 113 can be a beam splitter.
  • the coherent probe beam 118 impinges a surface 141 of the workpiece 140 at numerous points 143 or regions within the selected area 142 and is reflected back toward the measuring apparatus 110 .
  • the reflected probe beam contains phase information of the individual different points within the selected area 142 that corresponds to the profile of the surface 141 within the selected area 142 .
  • the reflected probe beam accordingly represents the individual points 143 in a manner generally analogous to discrete pixels.
  • the selected area 142 in the illustrated embodiment has a circular shape, in other embodiments, the selected area 142 may have a rectangular, triangular, elliptical, or other shape depending on the configuration of the optical element 113 .
  • the probe beam 118 impinges the surface 141 of the workpiece 140 at a specific number of discrete points 143 within the selected area 142 . Since the number of points 143 is fixed for a given hardware design, the probe beam 118 can be focused and the size of the area 142 can be selected for a desired resolution. For example, the probe beam 118 can be focused on a small area 142 of the surface 141 for a high resolution exposure, or the probe beam 118 can be focused on a larger area 142 of the surface 141 for a lower resolution exposure. In one embodiment, for example, the selected area 142 can be approximately one to two square inches, and the apparatus 110 can measure approximately one million points within the selected area 142 to determine the surface profile within the selected area 142 .
  • the measuring apparatus 110 further includes a sensing device 114 (shown schematically) for receiving the reflected probe beam and producing electrical signals based on the phase information in the reflected probe beam.
  • the electrical signals can be processed by the controller 170 to extract the surface profile information.
  • the sensing device 114 can be a Charge Coupled Device (CCD), Complementary Metal-Oxide Semiconductor (CMOS), or other photosensing medium.
  • the measuring apparatus 110 may also include gratings, lenses, and/or optical members for defracting and/or manipulating the reflected probe beam before the beam reaches the sensing device 114 .
  • Suitable measuring apparatuses include the system described in U.S. Pat. No. 6,031,611 entitled “Coherent Gradient Sensing Method and System for Measuring Surface Curvature,” which is herein incorporated by reference.
  • the illustrated system 100 further includes a positioning device 130 (shown in broken lines) coupled to the measuring apparatus 110 for moving the apparatus 110 relative to the workpiece 140 .
  • the positioning device 130 can move the measuring apparatus 110 along three orthogonal axes X, Y, and/or Z so that the probe beam 118 is directed toward different areas of the workpiece 140 .
  • the system 100 may include a driving assembly (not shown) for rotating the workpiece support 160 about an axis A-A and/or moving the workpiece support 160 along the axes X, Y, and/or Z.
  • the system 100 may not include the positioning device 130 or the driving assembly, but the measuring apparatus 110 can include a movable mirror to reflect the probe beam 118 toward selected areas of the workpiece 140 .
  • the controller 170 includes a computer-readable medium that operates the measuring apparatus 110 to direct the probe beam 118 toward selected areas of the workpiece 140 .
  • the measuring apparatus 110 can measure the surface profile of specific portions or the entire surface 141 of the workpiece 140 .
  • the apparatus 110 can quickly measure the profile of the entire perimeter region 144 of the workpiece 140 or a significant portion of the perimeter region 144 .
  • the measuring apparatus 110 can take measurements of discrete selected areas in the perimeter region 144 while moving continuously around the workpiece 140 .
  • the measuring apparatus 110 can move in a step fashion so that the apparatus 110 is stationary relative to the workpiece 140 while measuring the individual selected areas in the perimeter region 144 .
  • the selected areas can overlap or be contiguous so that the measuring apparatus 110 determines the surface profile of the entire perimeter region 144 .
  • One feature of the system 100 illustrated in FIG. 1 is that the apparatus 110 simultaneously measures numerous points within each selected area while taking discrete exposures of several selected areas in a desired region of the workpiece 140 .
  • An advantage of this feature is that the apparatus 110 quickly determines the profile of the desired region of the workpiece 140 because (a) the probe beam 118 measures numerous points simultaneously and (b) only a limited number of exposures are required.
  • the data has a high resolution and provides an accurate representation of the surface profile because the probe beam 118 focuses on the selected areas in the desired region and a large number of points on the workpiece 140 are measured within the individual selected areas.
  • the large number of points measured on the workpiece 140 reduces the likelihood that the workpiece 140 has significant variance between measured points.
  • the measurements are less sensitive to vibrations or displacement of the workpiece 140 .
  • the apparatus 110 can also measure the entire surface 141 of the workpiece 140 to determine the planarity of the workpiece 140 . In doing so, the apparatus 110 can scan concentric regions of the workpiece 140 , or alternatively, scan linear sections of the surface 141 as illustrated in FIG. 2 . In either case, while the apparatus 110 moves across the workpiece 140 , the probe beam 118 is focused on discrete areas with a selected size to provide a desired resolution. More specifically, the size of the discrete areas is selected so that the apparatus 110 can identify features and/or other nonuniformities on the surface 141 of the workpiece 140 .
  • the apparatus 110 can accordingly determine the planarity of the workpiece 140 accurately and quickly because (a) the probe beam 118 simultaneously measures numerous points on the workpiece 140 and (b) the probe beam 118 is focused to provide a desired resolution.
  • the large number of points measured on the workpiece 140 reduces the likelihood that the workpiece 140 has significant variance between measured points.
  • FIG. 3 is a schematic side cross-sectional view of the system 100 with the apparatus 110 measuring a depth D 1 of a trench 348 in the workpiece 140 .
  • the apparatus 110 determines the depth D 1 of the trench 348 by directing the probe beam 118 toward the trench 348 and measuring (a) a first distance D 2 between the apparatus 110 and a top surface 141 of the workpiece 140 and (b) a second distance D 3 between the apparatus 110 and a bottom surface 349 of the trench 348 .
  • the difference between the first distance D 2 and the second distance D 3 corresponds with the depth D, of the trench 348 .
  • the apparatus 110 may be able to measure the first and second distances D 2 and D 3 with a single probe beam 118 depending on the resolution of the beam 118 .
  • the apparatus 110 may also be able to determine a width W of the trench 348 due to the difference between the first and second distances D 2 and D 3 depending on the resolution of the beam 118 .
  • the apparatus 110 may also determine a length of the trench 348 with the probe beam 118 because the beam 118 measures different points along the length of the trench 348 .
  • the apparatus 110 may also be able to measure the dimensions of multiple features with the same probe beam 118 because the beam 118 simultaneously measures numerous points on the workpiece 140 .
  • the apparatus 110 can measure the depth D 1 of the first trench 348 and a depth of a second trench 348 a with the probe beam 118 .
  • the apparatus 110 can measure the thickness of positive features that project from the surface 141 of the workpiece 140 .
  • One feature of the system 100 illustrated in FIGS. 1-3 is that the probe beam 118 can be focused on an area 142 of the workpiece 140 to increase the resolution of the measured surface profile within the area 142 .
  • An advantage of this feature is that the increased resolution of the data provides a detailed and accurate representation of the dimensions of features within the selected area 142 . As such, the dimension can be measured quickly to ensure that the features are within specification.
  • FIG. 4 is a schematic side cross-sectional view of a system 400 for determining a change in the thickness of a feature on a workpiece 440 in accordance with another embodiment of the invention.
  • the system 400 is generally similar to the system 100 described above with reference to FIGS. 1-3 .
  • the illustrated system 400 includes a measuring apparatus 110 for producing a probe beam 118 , a workpiece support 460 for carrying the workpiece 440 , and a controller 170 for operating the measuring apparatus 110 and the workpiece support 460 .
  • the illustrated workpiece support 460 includes a surface 462 for supporting the workpiece 440 and a recess 464 defined in part by the surface 462 for receiving the workpiece W.
  • the workpiece support 460 may further include a plurality of holes 466 in the surface 462 and a vacuum line 468 connected to the holes 466 .
  • a vacuum pump 469 (shown schematically) can be coupled to the vacuum line 468 for drawing the back side of the workpiece 440 against the support surface 462 to secure the workpiece 440 to the workpiece support 460 .
  • the workpiece support 460 may not include the holes 466 and vacuum line 468 , and the system 400 may not include the vacuum pump 469 .
  • the workpiece support 460 draws the back side of the workpiece 440 against the surface 462 and holds the workpiece in a known and consistent configuration for measuring. Because processing can induce stress in the workpiece 440 that causes the workpiece 440 to deform, the workpiece support 460 advantageously draws the workpiece 440 against the surface 462 to reduce or eliminate such processing-induced deformation of the workpiece 440 .
  • the workpiece support 460 accordingly provides a consistent reference orientation for the workpiece 440 . As such, the measured difference in the surface contour before and after processing is a result of a change in the thickness of material on the workpiece 440 and not processing-induced deformation of the workpiece 440 .
  • the system 400 can measure a physical parameter of the workpiece 440 before and after a processing step to determine a change in the parameter.
  • the illustrated workpiece 440 includes a first layer 450 and a second layer 452 (shown in broken lines) deposited on the first layer 450 by atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), electroless plating, electroplating, or other suitable processes.
  • ALD atomic layer deposition
  • CVD chemical vapor deposition
  • PVD physical vapor deposition
  • electroless plating electroplating, or other suitable processes.
  • the system 400 can determine a thickness T of the second layer 452 by measuring (a) a first distance D 4 between a surface 451 of the first layer 450 and the apparatus 110 before the second layer 452 is deposited, and (b) a second distance D 5 between a surface 453 of the second layer 452 and the apparatus 110 after the second layer 452 is deposited.
  • the difference between the first distance D 4 and the second distance D 5 corresponds with the thickness T of the second layer 452 .
  • the difference between the first distance D 4 and the second distance D 5 is not affected by the process-induced deformation of the workpiece 440 because the workpiece support 460 holds the workpiece 440 in the same position for measuring before and after deposition.
  • the system 400 can also determine if the second layer 452 was deposited uniformly across the workpiece 440 . Because the apparatus 110 can measure the first and second distances D 4 and D 5 at numerous points across the workpiece 440 , the system 400 can calculate the thickness T of the second layer 452 at discrete points across the workpiece 440 . Variances in the thickness T of the second layer 452 can result from a nonuniform deposition process. As described in greater detail below with reference to FIG. 5 , the controller 170 can be operably coupled to a processing machine (e.g., deposition chamber) and provide feedback to the machine for adjusting process parameters to produce a workpiece within the specifications (e.g., a layer with a uniform thickness).
  • a processing machine e.g., deposition chamber
  • the system 400 can similarly determine (a) how much material has been removed during a chemical-mechanical planarization, etching, or other removal process by measuring the distance between the apparatus 110 and the surface of the workpiece before and after processing, and (b) whether the material was removed uniformly across the workpiece.
  • FIG. 5 is a schematic view of a system 500 for polishing a microfeature workpiece 540 in accordance with another embodiment of the invention.
  • the illustrated system 500 includes a measuring apparatus 110 for producing a probe beam 118 (shown in broken lines), a workpiece support 160 for carrying the workpiece 540 , and a polishing machine 575 for removing material from the workpiece 540 .
  • the illustrated polishing machine 575 includes a platen 576 , a planarizing pad 577 attached to the platen 576 , and a carrier head 580 over the planarizing pad 577 .
  • a drive assembly 583 (shown in broken lines) rotates the platen 576 (indicated by arrow G) and/or reciprocates the platen 576 back and forth (indicated by arrow F).
  • the carrier head 580 has a lower surface 581 to which the workpiece 540 may be attached, or the workpiece 540 may be attached to a pad (not shown) under the lower surface 581 .
  • the carrier head 580 is coupled to an actuator assembly 582 (shown schematically) to impart rotational motion to the workpiece 540 (indicated by arrow J) and/or reciprocate the workpiece 540 back and forth (indicated by arrow 1 ).
  • the planarizing pad 577 and a planarizing solution 579 define a planarizing medium that mechanically and/or chemically-mechanically removes material from the surface of the workpiece 540 .
  • the planarizing solution 579 may be a conventional CMP slurry with abrasive particles and chemicals that etch and/or oxidize the surface of the workpiece 540 , or the planarizing solution 579 may be a “clean” nonabrasive planarizing solution without abrasive particles.
  • the carrier head 580 presses the workpiece 540 face down against the planarizing solution 579 on a planarizing surface 578 of the planarizing pad 577 , and the platen 576 and/or the carrier head 580 moves to rub the workpiece 540 against the planarizing surface 578 .
  • the planarizing medium removes material from the workpiece 540 .
  • the workpiece 540 is positioned on the workpiece support 160 and the apparatus 110 measures the distance between a surface 541 of the workpiece 540 and the apparatus 110 before and after the workpiece 540 is polished.
  • the apparatus 110 measures the distances by directing the probe beam 118 toward selected areas of the workpiece 540 and simultaneously measuring the distance between the apparatus 110 and the workpiece 540 at a plurality of discrete points within each selected area.
  • the difference in the distance between the surface 541 and the apparatus 110 before and after polishing corresponds to the change in the thickness of the workpiece 540 .
  • the controller 170 can determine if the desired amount of material was removed during polishing.
  • the apparatus 110 can determine if the workpiece 540 has a uniformly planar surface after polishing. If the apparatus 110 determines that the surface 541 of the workpiece 110 is nonplanar, the controller 170 can provide instructions to the polishing machine 575 to change process parameters so that the polishing machine 575 forms a planar surface on subsequently polished workpieces.
  • the workpiece support 160 can be generally similar to the workpiece support 460 described above with reference to FIG. 4 and draw the workpiece 540 against the surface 462 to reduce or eliminate the deformation of the workpiece 540 due to processing-induced stress.

Abstract

Methods and systems for determining physical parameters of features on microfeature workpieces. In one embodiment, a method includes directing a substantially coherent probe beam at a selected area of a feature on the microfeature workpiece to produce a reflected probe beam having phase information of different points within the selected area. The selected area can be only a portion of the workpiece. The method further includes determining a physical parameter of the feature at the different points within the selected area of the workpiece based on the reflected probe beam. The physical parameter can be a depth, height, thickness, width, or other dimension of a layer, trench, hole, projection, or other feature on the workpiece.

Description

    TECHNICAL FIELD
  • The present invention relates to methods and systems for determining physical parameters of features on microfeature workpieces. More particularly, the invention is directed to methods and systems for measuring dimensions, changes in dimensions, planarity, and/or changes in planarity of features on workpieces.
    • BACKGROUND
  • Deposition, photolithography, etching, and doping are some of the primary processes used in the manufacture of microelectronic devices (e.g., dies) on semiconductor wafers. Microelectronic devices typically include submicron features formed on the wafer with precise dimensions. Errors in process steps can cause many problems including defective microelectronic devices. As such, the efficacy of the manufacturing processes must be qualified to ensure that the devices do not have defects and to determine whether anomalies are occurring in the processes. For example, after depositing a layer of material onto the wafer, the thickness of the layer can be measured to ensure that it is within the specification.
  • Metrology tools are used to measure various parameters of the wafer at different times during the production process and to ensure that the features formed on the wafer are within specification. One conventional metrology tool includes a laser that directs a small laser beam toward discrete points on the surface of the wafer to measure the distance between the laser and the surface at the individual points. For example, after removing material from the wafer via chemical-mechanical planarization (“CMP”), the planarity of the wafer surface should be checked because CMP processing may remove material from the perimeter region of the wafer at a different rate than from the center region of the wafer. To estimate the edge uniformity of the wafer, conventional metrology tools or other types of optoelectronic tools typically measure the distance between the wafer and the laser at 9 to 13 discrete points around the wafer perimeter. Based on the measurements at these different points, the tool estimates the edge uniformity of the wafer. Conventional systems similarly estimate the planarity of the surface by measuring the distance between the laser and the wafer at 30 to 50 discrete points across the wafer. Although these approaches are useful, the wafer surface may vary between the measured points and, accordingly, the results may not be accurate.
  • In other applications, metrology tools may estimate the thickness or change in thickness of a film by measuring the distance between the wafer and the laser at 30 to 50 discrete points before and after the film is deposited, etched or planarized. The difference between the before and after measurements corresponds to the thickness of the film or the change in film thickness. One problem with measuring 30 to 50 points before and after processing the wafer is that it is time consuming and reduces throughput. Moreover, the measurements may not provide an accurate representation of the film thickness because of variances across the wafer. Accordingly, there is a need for a fast and accurate process to determine physical features on the wafer.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a schematic isometric view of a system for measuring a physical parameter of a feature on a microfeature workpiece in accordance with one embodiment of the invention.
  • FIG. 2 schematically illustrates a process for scanning the workpiece in accordance with another embodiment of the invention.
  • FIG. 3 is a schematic side cross-sectional view of the system with an apparatus for measuring a depth of a feature on a workpiece.
  • FIG. 4 is a schematic side cross-sectional view of a system for determining a change in the thickness of a feature on a workpiece in accordance with another embodiment of the invention.
  • FIG. 5 is a schematic view of a system for polishing a microfeature workpiece in accordance with another embodiment of the invention.
    • DETAILED DESCRIPTION
  • A. Overview
  • The present invention is directed toward methods and systems for determining physical parameters of features on microfeature workpieces. In one embodiment, a method includes directing a substantially coherent probe beam at a selected area having a plurality of regions on the microfeature workpiece to produce a reflected probe beam having phase information of the individual regions within the selected area. The selected area can be only a portion of the workpiece. The method further includes determining a physical parameter of one or more features at the individual regions within the selected area of the workpiece based on the reflected probe beam. The physical parameter can be a depth, height, thickness, width, or other dimension of a layer, trench, hole, projection, or other feature on the workpiece.
  • In another embodiment, a method includes directing a substantially coherent probe beam toward a selected area of a feature on the microfeature workpiece to produce a first reflected probe beam having phase information of different points within the selected area. The method further includes processing the selected area of the workpiece, impinging the substantially coherent probe beam upon the selected area of the feature to generate a second reflected probe beam having phase information of different points within the selected area, and determining a change in a physical parameter of the feature in the selected area based on the first and second reflected probe beams. Processing the workpiece includes depositing material onto the workpiece and/or removing material from the workpiece.
  • Another aspect of the invention is directed to methods for polishing microfeature workpieces. In one embodiment, a method includes pressing a microfeature workpiece against a polishing pad, moving the workpiece relative to the polishing pad, and directing a substantially coherent probe beam at a selected area of a feature on the workpiece to produce a reflected probe beam having phase information of different points within the selected area. The method further includes determining a physical parameter of the feature at the different points within the selected area of the workpiece based on the reflected probe beam, and adjusting at least one polishing parameter in response to the determined physical parameter of the feature.
  • Another aspect of the invention is directed to systems for determining a physical parameter of a feature on a microfeature workpiece. In one embodiment, a system includes a radiation source for producing a substantially coherent probe beam, a sensing device for receiving a reflected probe beam and generating electrical signals based on the reflected probe beam, a workpiece support for positioning the microfeature workpiece in a path of the probe beam, and a controller. The controller has a computer-readable medium containing instructions to perform any one of the above-mentioned methods.
  • The present invention is directed toward methods and systems for determining physical parameters of features on microfeature workpieces. The term “microfeature workpiece” is used throughout to include substrates in and/or on which microelectronic devices, micromechanical devices, data storage elements, and other features are fabricated. For example, microfeature workpieces can be semiconductor wafers, glass substrates, insulated substrates, or many other types of substrates. Several specific details of the invention are set forth in the following description and in FIGS. 1-5 to provide a thorough understanding of certain embodiments of the invention. One skilled in the art, however, will understand that the present invention may have additional embodiments, or that other embodiments of the invention may be practiced without several of the specific features explained in the following description.
  • B. Embodiments of Systems for Measuring Physical Parameters of Features on Microfeature Workpieces
  • FIG. 1 is a schematic isometric view of a system 100 for measuring a physical parameter of a feature on a microfeature workpiece 140 in accordance with one embodiment of the invention. The system 100, for example, can measure the depth, thickness, and/or other dimensions or changes in a dimension of a feature on the workpiece 140. This is particularly useful in (a) qualifying workpieces after processing steps to ensure the workpieces are within specification, and (b) providing feedback to processing machines for modifying processing parameters to produce workpieces within specification.
  • The illustrated system 100 includes a measuring apparatus 110 for directing a coherent optical probe beam 118 along a beam path, a workpiece support 160 for positioning the workpiece 140 in the beam path, and a controller 170 (shown schematically) for operating the measuring apparatus 110 and/or the workpiece support 160. The measuring apparatus 110 includes a radiation source 112 (shown schematically) for producing the coherent probe beam 118, an optical element 113 (shown schematically) for directing the coherent probe beam 118 toward a selected area 142 of the workpiece 140, and a sensing device 114 for receiving a reflected probe beam. The radiation source 112 can be a laser, and the optical element 113 can be a beam splitter. As such, the coherent probe beam 118 impinges a surface 141 of the workpiece 140 at numerous points 143 or regions within the selected area 142 and is reflected back toward the measuring apparatus 110. The reflected probe beam contains phase information of the individual different points within the selected area 142 that corresponds to the profile of the surface 141 within the selected area 142. The reflected probe beam accordingly represents the individual points 143 in a manner generally analogous to discrete pixels. Although the selected area 142 in the illustrated embodiment has a circular shape, in other embodiments, the selected area 142 may have a rectangular, triangular, elliptical, or other shape depending on the configuration of the optical element 113.
  • In one embodiment, the probe beam 118 impinges the surface 141 of the workpiece 140 at a specific number of discrete points 143 within the selected area 142. Since the number of points 143 is fixed for a given hardware design, the probe beam 118 can be focused and the size of the area 142 can be selected for a desired resolution. For example, the probe beam 118 can be focused on a small area 142 of the surface 141 for a high resolution exposure, or the probe beam 118 can be focused on a larger area 142 of the surface 141 for a lower resolution exposure. In one embodiment, for example, the selected area 142 can be approximately one to two square inches, and the apparatus 110 can measure approximately one million points within the selected area 142 to determine the surface profile within the selected area 142.
  • The measuring apparatus 110 further includes a sensing device 114 (shown schematically) for receiving the reflected probe beam and producing electrical signals based on the phase information in the reflected probe beam. The electrical signals can be processed by the controller 170 to extract the surface profile information. The sensing device 114 can be a Charge Coupled Device (CCD), Complementary Metal-Oxide Semiconductor (CMOS), or other photosensing medium. The measuring apparatus 110 may also include gratings, lenses, and/or optical members for defracting and/or manipulating the reflected probe beam before the beam reaches the sensing device 114. Suitable measuring apparatuses include the system described in U.S. Pat. No. 6,031,611 entitled “Coherent Gradient Sensing Method and System for Measuring Surface Curvature,” which is herein incorporated by reference.
  • The illustrated system 100 further includes a positioning device 130 (shown in broken lines) coupled to the measuring apparatus 110 for moving the apparatus 110 relative to the workpiece 140. The positioning device 130 can move the measuring apparatus 110 along three orthogonal axes X, Y, and/or Z so that the probe beam 118 is directed toward different areas of the workpiece 140. In lieu of or in addition to the positioning device 130, the system 100 may include a driving assembly (not shown) for rotating the workpiece support 160 about an axis A-A and/or moving the workpiece support 160 along the axes X, Y, and/or Z. In other embodiments, the system 100 may not include the positioning device 130 or the driving assembly, but the measuring apparatus 110 can include a movable mirror to reflect the probe beam 118 toward selected areas of the workpiece 140.
  • The controller 170 includes a computer-readable medium that operates the measuring apparatus 110 to direct the probe beam 118 toward selected areas of the workpiece 140. Accordingly, the measuring apparatus 110 can measure the surface profile of specific portions or the entire surface 141 of the workpiece 140. For example, in one embodiment, the apparatus 110 can quickly measure the profile of the entire perimeter region 144 of the workpiece 140 or a significant portion of the perimeter region 144. To do so, the measuring apparatus 110 can take measurements of discrete selected areas in the perimeter region 144 while moving continuously around the workpiece 140. Alternatively, the measuring apparatus 110 can move in a step fashion so that the apparatus 110 is stationary relative to the workpiece 140 while measuring the individual selected areas in the perimeter region 144. The selected areas can overlap or be contiguous so that the measuring apparatus 110 determines the surface profile of the entire perimeter region 144.
  • One feature of the system 100 illustrated in FIG. 1 is that the apparatus 110 simultaneously measures numerous points within each selected area while taking discrete exposures of several selected areas in a desired region of the workpiece 140. An advantage of this feature is that the apparatus 110 quickly determines the profile of the desired region of the workpiece 140 because (a) the probe beam 118 measures numerous points simultaneously and (b) only a limited number of exposures are required. Moreover, the data has a high resolution and provides an accurate representation of the surface profile because the probe beam 118 focuses on the selected areas in the desired region and a large number of points on the workpiece 140 are measured within the individual selected areas. The large number of points measured on the workpiece 140 reduces the likelihood that the workpiece 140 has significant variance between measured points. Moreover, the measurements are less sensitive to vibrations or displacement of the workpiece 140.
  • The apparatus 110 can also measure the entire surface 141 of the workpiece 140 to determine the planarity of the workpiece 140. In doing so, the apparatus 110 can scan concentric regions of the workpiece 140, or alternatively, scan linear sections of the surface 141 as illustrated in FIG. 2. In either case, while the apparatus 110 moves across the workpiece 140, the probe beam 118 is focused on discrete areas with a selected size to provide a desired resolution. More specifically, the size of the discrete areas is selected so that the apparatus 110 can identify features and/or other nonuniformities on the surface 141 of the workpiece 140. The apparatus 110 can accordingly determine the planarity of the workpiece 140 accurately and quickly because (a) the probe beam 118 simultaneously measures numerous points on the workpiece 140 and (b) the probe beam 118 is focused to provide a desired resolution. The large number of points measured on the workpiece 140 reduces the likelihood that the workpiece 140 has significant variance between measured points.
  • In several applications, the apparatus 110 can measure the depth, thickness, width, and/or other dimensions of features on microfeature workpieces after material has been removed from or deposited onto the workpieces to ensure that the features have been properly formed. For example, FIG. 3 is a schematic side cross-sectional view of the system 100 with the apparatus 110 measuring a depth D1 of a trench 348 in the workpiece 140. The apparatus 110 determines the depth D1 of the trench 348 by directing the probe beam 118 toward the trench 348 and measuring (a) a first distance D2 between the apparatus 110 and a top surface 141 of the workpiece 140 and (b) a second distance D3 between the apparatus 110 and a bottom surface 349 of the trench 348. The difference between the first distance D2 and the second distance D3 corresponds with the depth D, of the trench 348. Depending on the size of the trench 348 and the alignment of the probe beam 118, the apparatus 110 may be able to measure the first and second distances D2 and D3 with a single probe beam 118 depending on the resolution of the beam 118. The apparatus 110 may also be able to determine a width W of the trench 348 due to the difference between the first and second distances D2 and D3 depending on the resolution of the beam 118. Moreover, the apparatus 110 may also determine a length of the trench 348 with the probe beam 118 because the beam 118 measures different points along the length of the trench 348.
  • Depending on the alignment of the probe beam 118, the apparatus 110 may also be able to measure the dimensions of multiple features with the same probe beam 118 because the beam 118 simultaneously measures numerous points on the workpiece 140. For example, the apparatus 110 can measure the depth D1 of the first trench 348 and a depth of a second trench 348 a with the probe beam 118. In other applications, the apparatus 110 can measure the thickness of positive features that project from the surface 141 of the workpiece 140.
  • One feature of the system 100 illustrated in FIGS. 1-3 is that the probe beam 118 can be focused on an area 142 of the workpiece 140 to increase the resolution of the measured surface profile within the area 142. An advantage of this feature is that the increased resolution of the data provides a detailed and accurate representation of the dimensions of features within the selected area 142. As such, the dimension can be measured quickly to ensure that the features are within specification.
  • FIG. 4 is a schematic side cross-sectional view of a system 400 for determining a change in the thickness of a feature on a workpiece 440 in accordance with another embodiment of the invention. The system 400 is generally similar to the system 100 described above with reference to FIGS. 1-3. For example, the illustrated system 400 includes a measuring apparatus 110 for producing a probe beam 118, a workpiece support 460 for carrying the workpiece 440, and a controller 170 for operating the measuring apparatus 110 and the workpiece support 460. The illustrated workpiece support 460 includes a surface 462 for supporting the workpiece 440 and a recess 464 defined in part by the surface 462 for receiving the workpiece W. The workpiece support 460 may further include a plurality of holes 466 in the surface 462 and a vacuum line 468 connected to the holes 466. A vacuum pump 469 (shown schematically) can be coupled to the vacuum line 468 for drawing the back side of the workpiece 440 against the support surface 462 to secure the workpiece 440 to the workpiece support 460. In other embodiments, the workpiece support 460 may not include the holes 466 and vacuum line 468, and the system 400 may not include the vacuum pump 469.
  • One feature of the illustrated system 400 is that the workpiece support 460 draws the back side of the workpiece 440 against the surface 462 and holds the workpiece in a known and consistent configuration for measuring. Because processing can induce stress in the workpiece 440 that causes the workpiece 440 to deform, the workpiece support 460 advantageously draws the workpiece 440 against the surface 462 to reduce or eliminate such processing-induced deformation of the workpiece 440. The workpiece support 460 accordingly provides a consistent reference orientation for the workpiece 440. As such, the measured difference in the surface contour before and after processing is a result of a change in the thickness of material on the workpiece 440 and not processing-induced deformation of the workpiece 440.
  • In several applications, the system 400 can measure a physical parameter of the workpiece 440 before and after a processing step to determine a change in the parameter. For example, the illustrated workpiece 440 includes a first layer 450 and a second layer 452 (shown in broken lines) deposited on the first layer 450 by atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), electroless plating, electroplating, or other suitable processes. The system 400 can determine a thickness T of the second layer 452 by measuring (a) a first distance D4 between a surface 451 of the first layer 450 and the apparatus 110 before the second layer 452 is deposited, and (b) a second distance D5 between a surface 453 of the second layer 452 and the apparatus 110 after the second layer 452 is deposited. The difference between the first distance D4 and the second distance D5 corresponds with the thickness T of the second layer 452. The difference between the first distance D4 and the second distance D5 is not affected by the process-induced deformation of the workpiece 440 because the workpiece support 460 holds the workpiece 440 in the same position for measuring before and after deposition.
  • The system 400 can also determine if the second layer 452 was deposited uniformly across the workpiece 440. Because the apparatus 110 can measure the first and second distances D4 and D5 at numerous points across the workpiece 440, the system 400 can calculate the thickness T of the second layer 452 at discrete points across the workpiece 440. Variances in the thickness T of the second layer 452 can result from a nonuniform deposition process. As described in greater detail below with reference to FIG. 5, the controller 170 can be operably coupled to a processing machine (e.g., deposition chamber) and provide feedback to the machine for adjusting process parameters to produce a workpiece within the specifications (e.g., a layer with a uniform thickness). In other applications, the system 400 can similarly determine (a) how much material has been removed during a chemical-mechanical planarization, etching, or other removal process by measuring the distance between the apparatus 110 and the surface of the workpiece before and after processing, and (b) whether the material was removed uniformly across the workpiece.
  • C. Embodiments of Systems of Polishing Workpieces
  • FIG. 5 is a schematic view of a system 500 for polishing a microfeature workpiece 540 in accordance with another embodiment of the invention. The illustrated system 500 includes a measuring apparatus 110 for producing a probe beam 118 (shown in broken lines), a workpiece support 160 for carrying the workpiece 540, and a polishing machine 575 for removing material from the workpiece 540. The illustrated polishing machine 575 includes a platen 576, a planarizing pad 577 attached to the platen 576, and a carrier head 580 over the planarizing pad 577. A drive assembly 583 (shown in broken lines) rotates the platen 576 (indicated by arrow G) and/or reciprocates the platen 576 back and forth (indicated by arrow F). The carrier head 580 has a lower surface 581 to which the workpiece 540 may be attached, or the workpiece 540 may be attached to a pad (not shown) under the lower surface 581. The carrier head 580 is coupled to an actuator assembly 582 (shown schematically) to impart rotational motion to the workpiece 540 (indicated by arrow J) and/or reciprocate the workpiece 540 back and forth (indicated by arrow 1).
  • The planarizing pad 577 and a planarizing solution 579 define a planarizing medium that mechanically and/or chemically-mechanically removes material from the surface of the workpiece 540. The planarizing solution 579 may be a conventional CMP slurry with abrasive particles and chemicals that etch and/or oxidize the surface of the workpiece 540, or the planarizing solution 579 may be a “clean” nonabrasive planarizing solution without abrasive particles. To planarize the workpiece 540, the carrier head 580 presses the workpiece 540 face down against the planarizing solution 579 on a planarizing surface 578 of the planarizing pad 577, and the platen 576 and/or the carrier head 580 moves to rub the workpiece 540 against the planarizing surface 578. As the workpiece 540 rubs against the planarizing surface 578, the planarizing medium removes material from the workpiece 540.
  • In several applications, the workpiece 540 is positioned on the workpiece support 160 and the apparatus 110 measures the distance between a surface 541 of the workpiece 540 and the apparatus 110 before and after the workpiece 540 is polished. As described above, the apparatus 110 measures the distances by directing the probe beam 118 toward selected areas of the workpiece 540 and simultaneously measuring the distance between the apparatus 110 and the workpiece 540 at a plurality of discrete points within each selected area. The difference in the distance between the surface 541 and the apparatus 110 before and after polishing corresponds to the change in the thickness of the workpiece 540. As such, the controller 170 can determine if the desired amount of material was removed during polishing. In lieu of or in addition to measuring a change in thickness, the apparatus 110 can determine if the workpiece 540 has a uniformly planar surface after polishing. If the apparatus 110 determines that the surface 541 of the workpiece 110 is nonplanar, the controller 170 can provide instructions to the polishing machine 575 to change process parameters so that the polishing machine 575 forms a planar surface on subsequently polished workpieces. In several embodiments, the workpiece support 160 can be generally similar to the workpiece support 460 described above with reference to FIG. 4 and draw the workpiece 540 against the surface 462 to reduce or eliminate the deformation of the workpiece 540 due to processing-induced stress.
  • From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.

Claims (80)

1. A method for measuring a physical parameter of a feature on a microfeature workpiece, the method comprising:
directing a substantially coherent probe beam at a selected area of a feature on the microfeature workpiece to produce a reflected probe beam having phase information of a plurality of different regions within the selected area simultaneously, the selected area being only a portion of the workpiece; and
determining a physical parameter of the feature at the different points within the selected area of the microfeature workpiece based on the reflected probe beam.
2. The method of claim 1 wherein:
directing the probe beam comprises illuminating the selected area of the workpiece with a radiation source; and
the method further comprises moving the radiation source relative to the microfeature workpiece while illuminating the selected area.
3. The method of claim 1 wherein:
directing the probe beam comprises illuminating the selected area of the workpiece with a radiation source; and
the radiation source is stationary relative to the microfeature workpiece while illuminating the selected area.
4. The method of claim 1 wherein directing the probe beam comprises illuminating a first selected area on the workpiece with a radiation source to produce a first reflected probe beam, and wherein the method further comprises:
moving the radiation source relative to the microfeature workpiece;
impinging the substantially coherent probe beam upon a second selected area of the feature to produce a second reflected probe beam having phase information of different points within the second selected area; and
measuring the physical parameter of the feature at the different points within the second selected area of the microfeature workpiece based on the second reflected probe beam.
5. The method of claim 1 wherein directing the probe beam comprises illuminating a perimeter portion of the workpiece.
6. The method of claim 1 wherein determining the physical parameter of the feature at the different points within the selected area comprises measuring a depth of the feature.
7. The method of claim 1 wherein determining the physical parameter of the feature at the different points within the selected area comprises measuring a thickness of the feature.
8. The method of claim 1 wherein determining the physical parameter of the feature at the different points within the selected area comprises measuring a width of the feature.
9. The method of claim 1 wherein determining the physical parameter of the feature at the different points within the selected area comprises measuring a dimension of the feature.
10. The method of claim 1, further comprising drawing a back side of the microfeature workpiece against a workpiece support while directing the coherent probe beam at the microfeature workpiece.
11. The method of claim 1 wherein the reflected probe beam is a first reflected probe beam, and wherein the method further comprises:
processing the selected area of the microfeature workpiece after directing the coherent probe beam at the selected area;
impinging the substantially coherent probe beam upon the selected area of the microfeature workpiece to generate a second reflected probe beam having phase information of different points within the selected area after processing the selected area; and
determining a change in the physical parameter of the feature at the selected area of the workpiece based on the first and second reflected probe beams.
12. A method for measuring a dimension of a feature on a microfeature workpiece, the method comprising:
impinging a substantially coherent probe beam upon a selected area of a feature of the microfeature workpiece; and
analyzing a reflected probe beam having phase information of discrete points within the selected area to determine a dimension of the feature within the selected area.
13. The method of claim 12 wherein analyzing the reflected probe beam comprises determining a depth of the feature.
14. The method of claim 12 wherein analyzing the reflected probe beam comprises determining a width of the feature.
15. The method of claim 12 wherein analyzing the reflected probe beam comprises determining a thickness of the feature.
16. The method of claim 12 wherein impinging the probe beam upon the workpiece comprises directing the probe beam at only a portion of the workpiece.
17. The method of claim 12 wherein impinging the probe beam upon the workpiece comprises illuminating a first selected area on the workpiece with a radiation source to produce a first reflected probe beam, and wherein the method further comprises:
moving the radiation source relative to the microfeature workpiece;
directing the substantially coherent probe beam at a second selected area of the feature to produce a second reflected probe beam having phase information of different points within the second selected area; and
determining the dimension of the feature at the different points within the second selected area of the microfeature workpiece based on the second reflected probe beam.
18. The method of claim 12, further comprising drawing a back side of the microfeature workpiece against a workpiece support with a vacuum pump while impinging the probe beam upon the workpiece.
19. The method of claim 12 wherein the reflected probe beam is a first reflected probe beam, and wherein the method further comprises:
processing the selected area of the microfeature workpiece after impinging the probe beam upon the selected area of the workpiece;
directing the substantially coherent probe beam at the selected area of the microfeature workpiece to generate a second reflected probe beam having phase information of different points within the selected area after processing the selected area; and
determining a change in the dimension of the feature at the selected area of the workpiece based on the first and second reflected probe beams.
20. A method for measuring a change in a physical parameter of a feature on a microfeature workpiece, the method comprising:
directing a substantially coherent probe beam toward a selected area of a feature on the microfeature workpiece to produce a first reflected probe beam having concurrent phase information of different points within the selected area;
processing the selected area of the workpiece after directing the probe beam toward the selected area;
impinging the substantially coherent probe beam upon the selected area of the feature to generate a second reflected probe beam having phase information of different points within the selected area after processing the selected area; and
determining a change in a physical parameter of the feature in the selected area based on the first and second reflected probe beams.
21. The method of claim 20 wherein processing the workpiece comprises depositing material onto the workpiece at the selected area.
22. The method of claim 20 wherein processing the workpiece comprises removing material from the workpiece at the selected area.
23. The method of claim 20 wherein determining the change in the physical parameter comprises calculating the change in a thickness of a layer on the workpiece.
24. The method of claim 20 wherein determining the change in the physical parameter comprises calculating the change in a dimension of a layer on the workpiece.
25. The method of claim 20 wherein directing the probe beam comprises illuminating only a portion of the workpiece.
26. A method for measuring a physical parameter of a feature on a microfeature workpiece, the method comprising:
exposing a first selected area of a feature on a microfeature workpiece to a substantially coherent probe beam with a radiation source and generating a first reflected probe beam having phase information of different points within the first selected area;
moving the radiation source relative to the microfeature workpiece;
illuminating a second selected area of the feature with the substantially coherent probe beam and generating a second reflected probe beam having phase information of different points within the second selected area, the second selected area being spaced apart from the first selected area; and
analyzing the first and second reflected probe beams to determine a physical parameter of the feature in the first and second selected areas of the microfeature workpiece.
27. The method of claim 26 wherein the radiation source is stationary relative to the workpiece while exposing and illuminating the workpiece.
28. The method of claim 26 wherein the radiation source moves relative to the workpiece while exposing and illuminating the workpiece.
29. The method of claim 26 wherein analyzing the first and second reflected probe beams comprises determining a depth of the feature in the first and second selected areas.
30. The method of claim 26 wherein analyzing the first and second reflected probe beams comprises determining a width of the feature in the first and second selected areas.
31. The method of claim 26 wherein analyzing the first and second reflected probe beams comprises determining a thickness of the feature in the first and second selected areas.
32. A method for determining a dimension of a feature on a microfeature workpiece, the method comprising:
directing a substantially coherent probe beam at a selected area of a feature on the microfeature workpiece with a radiation source to produce a reflected probe beam;
receiving the reflected probe beam with a sensing device, the reflected probe beam having phase information of different points within the selected area;
producing electrical signals with the sensing device based on the reflected probe beam; and
analyzing the electrical signals with a processor to determine a dimension of the feature in the selected area of the microfeature workpiece.
33. The method of claim 32 wherein analyzing the electrical signals comprises determining a depth of the feature.
34. The method of claim 32 wherein analyzing the electrical signals comprises determining a thickness of the feature.
35. A method for measuring a change in a physical parameter of a feature on a microfeature workpiece, the method comprising:
positioning a microfeature workpiece on and/or in a workpiece support;
drawing a back side of the microfeature workpiece against the workpiece support with a vacuum pump;
directing a substantially coherent probe beam at a selected area of a feature on the microfeature workpiece to produce a first reflected probe beam having phase information of different points within the selected area while drawing the back side of the workpiece against the workpiece carrier;
processing the microfeature workpiece after directing the probe beam at the workpiece;
placing the microfeature workpiece on and/or in the workpiece support after processing the workpiece;
urging the back side of the microfeature workpiece against the workpiece support with the vacuum pump;
impinging the substantially coherent probe beam upon the selected area of the feature to produce a second reflected probe beam having phase information of different points within the selected area while urging the back side of the workpiece against the workpiece support; and
analyzing the first and second reflected probe beams to determine a change in a dimension of the feature in the selected area of the microfeature workpiece.
36. The method of claim 35 wherein processing the workpiece comprises depositing material onto the workpiece at the selected area.
37. The method of claim 35 wherein processing the workpiece comprises removing material from the workpiece at the selected area.
38. The method of claim 35 wherein analyzing the first and second reflected probe beams comprises calculating the change in a thickness of a layer on the workpiece.
39. A method for polishing microfeature workpieces, the method comprising:
pressing a microfeature workpiece against a polishing pad and moving the workpiece relative to the polishing pad;
directing a substantially coherent probe beam at a selected area of a feature on the microfeature workpiece to produce a reflected probe beam having phase information of different points within the selected area;
determining a physical parameter of the feature at the different points within the selected area of the microfeature workpiece based on the reflected probe beam; and
adjusting at least one polishing parameter in response to the determined physical parameter of the feature.
40. The method of claim 39 wherein determining the physical parameter comprises calculating a planarity of a surface of the workpiece within the selected area.
41. The method of claim 39 wherein directing the probe beam at the selected area comprises impinging a perimeter region of the workpiece with the probe beam.
42. The method of claim 39 wherein adjusting at least one polishing parameter comprises changing at least one polishing parameter for polishing other workpieces.
43. The method of claim 39 wherein directing the probe beam comprises illuminating a first selected area on the workpiece with a radiation source to produce a first reflected probe beam, and wherein the method further comprises:
moving the radiation source relative to the microfeature workpiece;
impinging the substantially coherent probe beam upon a second selected area of the feature to produce a second reflected probe beam having phase information of different points within the second selected area; and
measuring the physical parameter of the feature at the different points within the second selected area of the microfeature workpiece based on the second reflected probe beam;
wherein adjusting at least one polishing parameter comprises changing at least one polishing parameter in response to the determined physical parameter of the feature in the first and second areas of the workpiece.
44. The method of claim 39 wherein determining the physical parameter of the feature at the different points within the selected area comprises measuring a thickness.
45. The method of claim 39, further comprising drawing a back side of the microfeature workpiece against a workpiece support while directing the coherent probe beam at the microfeature workpiece.
46. A method for polishing microfeature workpieces, the method comprising:
directing a substantially coherent probe beam toward a selected area of a feature on a microfeature workpiece to produce a first reflected probe beam having phase information of different points within the selected area;
pressing the microfeature workpiece against a polishing pad and moving the workpiece relative to the polishing pad after directing the probe beam toward the workpiece;
impinging the substantially coherent probe beam upon the selected area of the feature to generate a second reflected probe beam having phase information of different points within the selected area after pressing the microfeature workpiece against the polishing pad;
determining a change in a physical parameter of the feature within the selected area based on the first and second reflected probe beams; and
adjusting at least one polishing parameter in response to the change in the physical parameter of the feature.
47. The method of claim 46 wherein determining the change in the physical parameter comprises calculating the change in a planarity of a surface of the workpiece within the selected area.
48. The method of claim 46 wherein determining the change in the physical parameter comprises calculating the change in a thickness of the workpiece at the selected area.
49. The method of claim 46, further comprising drawing a back side of the microfeature workpiece against a workpiece support while directing the coherent probe beam at the microfeature workpiece.
50. A system for determining a physical parameter of a feature on a microfeature workpiece, the system comprising:
a radiation source for producing a substantially coherent probe beam;
a sensing device for receiving a reflected probe beam and generating electrical signals based on the reflected probe beam;
a workpiece support for positioning the microfeature workpiece in a path of the probe beam; and
a controller operably coupled to the radiation source, the sensing device, and the workpiece support, the controller having a computer-readable medium containing instructions to perform a method comprising—
directing the substantially coherent probe beam at a selected area of a feature on the microfeature workpiece to produce the reflected probe beam having phase information of a plurality of discrete regions within the selected area simultaneously, the selected area being only a portion of the workpiece; and
determining a physical parameter of the feature at the different points within the selected area of the workpiece based on the reflected probe beam.
51. The system of claim 50, further comprising an optical element for directing the coherent probe beam along the path.
52. The system of claim 50, further comprising a positioning device coupled to the radiation source for moving the radiation source relative to the workpiece support.
53. The system of claim 50 wherein the computer-readable medium instruction determining the physical parameter of the feature at the different points within the selected area comprises measuring a depth of the feature.
54. The system of claim 50 wherein the computer-readable medium instruction determining the physical parameter of the feature at the different points within the selected area comprises measuring a thickness of the feature.
55. The system of claim 50 wherein the computer-readable medium instruction determining the physical parameter of the feature at the different points within the selected area comprises measuring a width of the feature.
56. The system of claim 50 wherein the computer-readable medium instruction determining the physical parameter of the feature at the different points within the selected area comprises measuring a dimension of the feature.
57. The system of claim 50 wherein the workpiece support comprises a plurality of apertures and a vacuum line in fluid communication with the apertures, and wherein the system further comprises a vacuum pump operably coupled to the vacuum line for drawing a back side of the microfeature workpiece against the workpiece support.
58. A system for determining a dimension of a feature on a microfeature workpiece, the system comprising:
a radiation source for producing a substantially coherent probe beam;
a sensing device for receiving a reflected probe beam and generating electrical signals based on the reflected probe beam;
a workpiece support for positioning the microfeature workpiece in a path of the probe beam; and
a controller operably coupled to the radiation source, the sensing device, and the workpiece support, the controller having a computer-readable medium containing instructions to perform a method comprising—
impinging the substantially coherent probe beam upon a selected area of a feature of the microfeature workpiece; and
analyzing the reflected probe beam having phase information of discrete points within the selected area to determine a dimension of the feature within the selected area.
59. The system of claim 58 wherein the workpiece support comprises a plurality of apertures and a vacuum line in fluid communication with the apertures, and wherein the system further comprises a vacuum pump operably coupled to the vacuum line for drawing a back side of the microfeature workpiece against the workpiece support.
60. The system of claim 58, further comprising a positioning device coupled to the radiation source for moving the radiation source relative to the workpiece support.
61. A system for measuring a change in a physical parameter of a feature on a microfeature workpiece, the system comprising:
a radiation source for producing a substantially coherent probe beam;
a sensing device for receiving reflected probe beams and generating electrical signals based on the reflected probe beams;
a workpiece support for positioning the microfeature workpiece in a path of the probe beam; and
a controller operably coupled to the radiation source, the sensing device, and the workpiece support, the controller having a computer-readable medium containing instructions to perform a method comprising—
directing the substantially coherent probe beam toward a selected area of a feature on the microfeature workpiece to produce a first reflected probe beam having concurrent phase information of different points within the selected area;
processing the selected area of the workpiece after directing the probe beam toward the selected area;
impinging the substantially coherent probe beam upon the selected area of the feature to generate a second reflected probe beam having phase information of different points within the selected area after processing the selected area; and
determining a change in a physical parameter of the feature in the selected area based on the first and second reflected probe beams.
62. The system of claim 61 wherein the workpiece support comprises a plurality of apertures and a vacuum line in fluid communication with the apertures, and wherein the system further comprises a vacuum pump operably coupled to the vacuum line for drawing a back side of the microfeature workpiece against the workpiece support.
63. The system of claim 61, further comprising a positioning device coupled to the radiation source for moving the radiation source relative to the workpiece support.
64. The system of claim 61, further comprising a deposition chamber for processing the workpiece.
65. The system of claim 61, further comprising a polishing machine for processing the workpiece.
66. The system of claim 61 wherein the computer-readable medium instruction determining the change in the physical parameter comprises calculating the change in a thickness of a layer on the workpiece.
67. The system of claim 61 wherein the computer-readable medium instruction determining the change in the physical parameter comprises calculating the change in a dimension of a layer on the workpiece.
68. The system of claim 61 wherein the computer-readable medium instruction determining the change in the physical parameter comprises calculating the change in a planarity of a surface on the workpiece.
69. A system for measuring a physical parameter of a feature on a microfeature workpiece, the system comprising:
a radiation source for producing a substantially coherent probe beam;
a sensing device for receiving reflected probe beams and generating electrical signals based on the reflected probe beams;
a workpiece support for positioning the microfeature workpiece in a path of the probe beam; and
a controller operably coupled to the radiation source, the sensing device, and the workpiece support, the controller having a computer-readable medium containing instructions to perform a method comprising—
exposing a first selected area of a feature on the microfeature workpiece to the substantially coherent probe beam and generating a first reflected probe beam having phase information of different points within the first selected area;
moving the radiation source relative to the microfeature workpiece;
illuminating a second selected area of the feature with the substantially coherent probe beam and generating a second reflected probe beam having phase information of different points within the second selected area, the second selected area being spaced apart from the first selected area; and
analyzing the first and second reflected probe beams to determine a physical parameter of the feature in the first and second selected areas of the microfeature workpiece.
70. The system of claim 69 wherein the workpiece support comprises a plurality of apertures and a vacuum line in fluid communication with the apertures, and wherein the system further comprises a vacuum pump operably coupled to the vacuum line for drawing a back side of the microfeature workpiece against the workpiece support.
71. The system of claim 69, further comprising a positioning device coupled to the radiation source for moving the radiation source relative to the workpiece support.
72. A system for polishing a microfeature workpiece, the system comprising:
a radiation source for producing a substantially coherent probe beam;
a sensing device for receiving a reflected probe beam and generating electrical signals based on the reflected probe beam;
a workpiece support for positioning the microfeature workpiece in a path of the probe beam;
a polishing pad;
a workpiece carrier over the polishing pad; and
a controller operably coupled to the radiation source, the sensing device, the workpiece support, the polishing pad, and the workpiece carrier, the controller having a computer-readable medium containing instructions to perform a method comprising—
pressing the microfeature workpiece against the polishing pad and moving the workpiece relative to the polishing pad;
directing the substantially coherent probe beam at a selected area of a feature on the microfeature workpiece to produce the reflected probe beam having phase information of different points within the selected area;
determining a physical parameter of the feature at the different points within the selected area of the microfeature workpiece based on the reflected probe beam; and
adjusting at least one polishing parameter in response to the determined physical parameter of the feature.
73. The system of claim 72 wherein the workpiece support comprises a plurality of apertures and a vacuum line in fluid communication with the apertures, and wherein the system further comprises a vacuum pump operably coupled to the vacuum line for drawing a back side of the microfeature workpiece against the workpiece support.
74. The system of claim 72, further comprising a positioning device coupled to the radiation source for moving the radiation source relative to the workpiece support.
75. The system of claim 72 wherein the computer-readable medium instruction determining the physical parameter comprises calculating a planarity of a surface of the workpiece within the selected area.
76. A system for polishing a microfeature workpiece, the system comprising:
a radiation source for producing a substantially coherent probe beam;
a sensing device for receiving reflected probe beams and generating electrical signals based on the reflected probe beams;
a workpiece support for positioning the microfeature workpiece in a path of the probe beam;
a polishing pad;
a workpiece carrier over the polishing pad; and
a controller operably coupled to the radiation source, the sensing device, the workpiece support, the polishing pad, and the workpiece carrier, the controller having a computer-readable medium containing instructions to perform a method comprising—
directing the substantially coherent probe beam toward a selected area of a feature on the microfeature workpiece to produce a first reflected probe beam having phase information of different points within the selected area;
pressing the microfeature workpiece against the polishing pad and moving the workpiece relative to the polishing pad after directing the probe beam toward the workpiece;
impinging the substantially coherent probe beam upon the selected area of the feature to generate a second reflected probe beam having phase information of different points within the selected area after pressing the microfeature workpiece against the polishing pad;
determining a change in a physical parameter of the feature in the selected area based on the first and second reflected probe beams; and
adjusting at least one polishing parameter in response to the change in the physical parameter of the feature.
77. The system of claim 76 wherein the workpiece support comprises a plurality of apertures and a vacuum line in fluid communication with the apertures, and wherein the system further comprises a vacuum pump operably coupled to the vacuum line for drawing a back side of the microfeature workpiece against the workpiece support.
78. The system of claim 76, further comprising a positioning device coupled to the radiation source for moving the radiation source relative to the workpiece support.
79. The system of claim 76 wherein the computer-readable medium instruction determining the change in the physical parameter comprises calculating the change in a planarity of a surface of the workpiece within the selected area.
80. The system of claim 76 wherein the computer-readable medium instruction determining the change in the physical parameter comprises calculating the change in a thickness of the workpiece at the selected area.
US10/930,307 2004-08-31 2004-08-31 Methods and systems for determining physical parameters of features on microfeature workpieces Abandoned US20060046618A1 (en)

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