WO1997038355A1

WO1997038355A1 - Systems and methods for deposition of dielectric films

Info

Publication number: WO1997038355A1
Application number: PCT/US1997/005742
Authority: WO
Inventors: J. David Casey, Jr.; Diane K. Stewart; Ganesh Sundaram; Andrew F. Doyle
Original assignee: Micrion Corporation
Priority date: 1996-04-08
Filing date: 1997-04-07
Publication date: 1997-10-16

Abstract

The present invention provides systems and methods for the water-based deposition of silicon dioxide films. In one aspect, the invention provides methods for depositing a dielectric material to the surface of a workpiece. The workpiece can be, for example, an integrated circuit, a phase shift mask, or any other device that has features suitable for processing by a focused ion beam system. The method for depositing the dielectric material includes the steps of providing a chamber that has an interior portion with a stage element for holding the workpiece and that also includes an injection element for introducing reactant material into that interior portion, introducing through the injection elements a silicon-containing reactant material, introducing through the injection element a water-containing reactant material, and passing an ion beam through the interior portion and to the surface of the workpiece for depositing the dielectric material thereon. The process of the invention is suitable for focused ion beam induced deposition of a silicon dioxide film on top of an integrated circuit for forming an insulated layer or for depositing a silicon dioxide film on a phase shift mask for repairing a defect in the mask such as a bump or a void.

Description

SYSTEMS AND METHODS FOR DEPOSITION OF DIELECTRIC FILMS

Field of the Invention

The invention relates to systems and methods for micrometer and submicrometer lithography and more particularly to systems and methods for the deposition of dielectric films, including silicon dioxide films, to repair advanced lithography masks and to modify integrated circuits.

Background of the Invention Particle beam deposition processes are known for depositing materials onto the surface of an integrated circuit, photo mask, or other workpiece. Generally, these processes deposit either a conductive material or a dielectric material. A dielectric material is generally understood as a material that can act as electric insulation. A conductive material is generally understood as a material that conducts electricity. The conducting materials form circuit elements such as wires, and the dielectric materials form insulating elements such as wire insulation.

To achieve the particle beam induced deposition of a dielectric material, the workpiece is placed into a vacuum chamber which is evacuated of air. Select gases enter into the chamber at a point that is proximate to the surface of the workpiece. The particle beam passes through the gases and onto the surface of the workpiece to induce the deposition of a dielectric material, such as Siθ2, onto the surface of the workpiece.

One known technique for depositing a dielectric film employs a silicon ion beam, tetramethoxysilane (TMOS) and oxygen gas. In this technique, both gases pass into an evacuated chamber through a single nozzle that directs these reactant gases toward the surface of the workpiece. The nozzle connects to two separate gas reservoirs each of which holds a separate one of the reactant gases. A 60 kV Si focused ion beam passes through the chamber and onto the surface of the workpiece to induce the deposition of silicon dioxide at the surface. The resultant deposition forms a film consisting of silicon and oxygen and having sufficient resistivity to act as an insulator for integrated circuit repair.

Although this known process works for generating a film of silicon dioxide dielectric material, the technique requires a silicon ion beam, which is an expensive and complicated piece of equipment. Moreover, the deposited dielectric material can be sufficiently stained or darkened as to attenuate actinic radiation, and can be sufficiently contaminated to increase the conductivity of the dielectric film. For these reasons, among others, this process is ill suited for commercial operation. Accordingly, it is an object of the present invention to provide systems and methods for deposition of dielectric films that have improved characteristics of transmittance for lithographic wavelengths.

It is a further object of the present invention to provide systems and methods for the deposition of dielectric films that have improved electrical properties and form better insulator layers.

It is still another object of the present invention to provide systems and methods for focused ion beam deposition of dielectric films that have improved deposition yields.

It is a further object of the present invention to provide safe and reliable systems and methods for the deposition of a dielectric material that provides more precise control of reactant materials.

It is a further object of the present invention to provide deposition systems and methods that provide deposition techniques suitable for filling substrate holes that have high aspect ratios and that allow more exact placement of insulator deposition on substrates susceptible to charge build up.

Other objects of the present invention will be made clear by the following description of the invention.

Summary of the Invention The present invention provides systems and methods for the water-based deposition of silicon dioxide films. Although not to be bound by theory, it is understood that processes of the invention achieve improved rates of deposition and improved dielectric films as the strength of the polar characteristic of water provides deposition processes that are more reactive and provide greater adsorption than prior deposition processes that employ O2-based deposition.

In one aspect, the invention provides methods for depositing a dielectric material onto the surface of a workpiece. The workpiece can be, for example, an integrated circuit, a phase shift mask, or any other device that has features suitable for processing by micrometer or submicrometer lithographic techniques. One process for depositing a dielectric material includes the steps of providing a chamber that has an interior portion with a stage element for holding the workpiece and that has an injection element for introducing reactant material into that interior portion, the further step of introducing through the injection elements a silicon-containing reactant material, introducing through the injection element a water-containing reactant material, and passing a beam through the interior portion and to the surface of the workpiece for depositing the dielectric material thereon. The processes of the invention are suitable for particle beam induced deposition of silicon dioxide films onto a surface of an integrated circuit for forming an insulation layer or for depositing a silicon dioxide film on a phase shift mask for repairing a defect in the mask such as a bump or a void.

The term silicon-containing reactant material, as used herein, encompasses any compound that includes a silicon atom within the skeleton of that compound. For example, the term silicon-containing reactant material encompasses silanes, siloxanes, silazanes, compounds containing silyl groups, silylene groups, disilanyl groups, siloxanyl groups, trimethylsilyl groups, tert-butyldimethylsilyl groups and trimethylsiloxy groups, cyclic silanes, silanols, and organosilicons. The term water-containing material as used herein, encompasses any water- containing solution suitable for use with the processes of the present invention.

The term particle beam as used herein, encompasses ion beams, electron beams, neutral particle beams, x-ray beams and any other directed radiation suitable for inducing the deposition of a dielectric film. Moreover, as explained in greater detail hereinafter, the term particle beam shall include ion beams, including gallium ion beams generated by commercially available focused ion beam (FIB) systems and inert gas (for example, helium and argon) ion beams generated by a gas field ion source (GFIS). In one practice of the invention, the step of introducing a silicon-containing reactant material, can include the introduction of a siloxane-containing reactant material. As the term siloxane is used herein, this term encompasses compounds whose skeleton includes silicon and oxygen bonds.

In a preferred embodiment the siloxane-containing reactant material is tetramethylcyclotetrasiloxane (TMCTS). However it should be apparent to one of ordinary skill in the art of film deposition that other suitable siloxane materials such as tetraethyloxysiloxane (TEOS), disiloxane, trisiloxane, pentamethyldisiloxane, hexamethyldisiloxane, octamethylcyclotetrasiloxane, octamethyltrisiloxane, octaphenylcyclotetrasiloxane, and other such siloxane compounds can be practiced with the present invention without departing from the scope thereof.

In one further practice of the invention, the silicon-containing material is introduced into the chamber to a pressure in a range of about 0.1 -3.0 torr, as measured at a point along the delivery system. Typically the silicon-containing material is introduced into the chamber through a gas delivery system that includes a reservoir or other supply of source material that connects by a conduit to the interior portion of the chamber. In a preferred embodiment of the invention the injection element includes two separate nozzles connected to two separate reservoirs. Each reservoir contains one of the reactant materials, one containing the silicon-containing material, the second containing the water-containing material. Preferably each conduit includes a separate, closed-loop, delivery pressure control mechanism. With this configuration, the system, among other things, prevents mixing of the reactant materials before the materials enter the chamber, and further provides greater control over the delivery pressures of the reactant materials.

In a further embodiment of the invention, the process provides an injection element with an input nozzle that has two jet elements and the deposition is induced by an ion beam. Each jet element is disposed approximately 2-16 mils, and preferably 8-12 mils, above the surface of the workpiece and disposed laterally approximately 50-700 microns (optimally 300-400 microns) from the center of the ion beam.

In a further step, the process introduces into the chamber a water-containing reactant material that contains water and preferably introduces water to a pressure of between 0.5 and 6 torr, and optimally 2-3 torr, as measured at a point along the delivery system.

In a further step, processes of the invention provide a charge neutralization element for reducing charge build up on a substrate surface, which can occur during the ion beam induced deposition processes. Accordingly, processes according to the invention provide improved submicrometer placement of Siθ2 films. Systems and methods according to the present invention provide for, inter alia, liquid metal ion beam deposition of dielectric films that have high resistivities. Accordingly, it is understood that the systems and processes of the invention produce dielectric films with reduced metal ion contamination, which is understood to provide films with improved resistivities and reduced discoloration or staining. Moreover, systems and methods according to the invention provide deposition processes that can operate without compressed gases.

The foregoing summary, as well as the following detailed description of the exemplary embodiments of the invention, will be better understood when read in conjunction with the appended figures. For purposes of illustrating the invention, the provided figures depict embodiments that are presently preferred. It is to be understood that the invention is not limited to the precise arrangements and instrumentalities shown.

Brief Description of the Drawings

Figure 1 is a schematic representation of a focused ion beam system for use with processes according to the present invention; Figure 2 is a diagrammatic representation of one process of the invention for depositing dielectric material onto the surface of a workpiece;

Figures 3A-3D are sequential views of a process for repairing a semiconductor device according to the invention; Figure 4 depicts six films deposited according to one practice of the invention; and

Figure 5 depicts six additional films deposited according to a further practice of the invention.

Detailed Description of the Illustrated Embodiments

In one aspect, the invention is realized as processes that include a water- containing reactant material that mixes with a silicon-containing reactant material and that employs a particle beam to deposit dielectric films. The disclosed processes have a greater rate of deposition and deposit films with improved properties of resistivity and optical transmissivity. Although not wishing to be bound by theory, the disclosed water- based deposition processes are understood to be superior to O2-based deposition processes as water is more polar. These water-based processes are understood to be more reactive and provide greater adsorption at the workpiece surface. The combination of siloxane-containing materials and water-containing materials can provide superior dielectric films.

Processes and systems utilizing particle beam deposition are disclosed herein that can deposit dielectric films suitable for use as, for example, insulator layers for repairing and rewiring integrated circuits, including VLSI and ULSI circuits, and for use as optically transmissive repair films deposited on the surface of, for example, phase shift masks, for repairing defects such as voids and bumps or other defects that interfere with the correct transfer of pattern features during lithographic fabrication processes. The invention can also be understood as high quality dielectric films produced by the processes described herein.

As used herein, the term "dielectric film" is understood to refer to a film that has high resistivity to the conduction of electricity. In particular, the term dielectric film is used herein to encompass silicon-containing films, such as silicon dioxide films. The dielectric films of the invention may be substantially pure, or may contain a mixture of materials including a mixture of phases of silicon-containing materials, carbon- containing materials, contaminants from an incident particle beam and other materials that enter the film during the processes of the invention. To prepare dielectric films according to one preferred embodiment of the invention, FIB induced deposition is employed. The term FIB induced deposition, as used herein, is understood to encompass a deposition process that disposes a workpiece into a chamber, and introduces a reactant material into the chamber. The reactant material is typically in a gaseous form and enters the chamber through one or more deposition nozzles that are disposed within the chamber and positioned above the surface of the workpiece. The nozzles direct the reactant material toward the upper surface of the workpiece. A focused ion beam, directed to the surface of the workpiece, induces, accelerates or effects the deposition of material onto the surface of the workpiece.

FIB deposition techniques for placing workpieces within a chamber, directing gases to the surface of the workpiece and passing a particle beam through the chamber and onto the surface of the workpiece are known in the art and described in publications in the art including Komano et al., "Insulator Deposition By A Focused Ion Beam," Japanese Journal of Applied Physics, Vol. 28, p. 2372, (1989); Nakamura et al. "Silicon Dioxide Deposition Into A Hole Using A Focused Ion Beam," Japanese Journal of Applied Physics, Vol. 30, p. 3238, (1991); and U.S. Patent 5,429,730 issued to Nakamura et al.; all of which are herein incorporated by reference.

In the preferred embodiment of the invention, a liquid metal ion source (LMIS) or a gas field ion source (GFIS) generates the ion beam and directs Ga, Si, Be, He, H or other ion or ion combination to the surface of the workpiece at working voltages of between 4kv and 50kv. However, it should be obvious to one of ordinary skill in the art of semiconductor fabrication and repair, that the substitution of an ion beam for any other particle beam, including neutral particle beams, x-ray beams or other such beam or beam combination, may be practiced with the present invention without departing from the scope thereof. Further, dielectric films of the present invention may be deposited without action of a particle beam and may be developed by chemical vapor deposition techniques known in the art without departing from the scope of the invention that includes water-containing reactant materials and silicon-containing reactant materials for depositing dielectric films on a workpiece surface.

To prepare dielectric films, a FIB system suited for the process of the invention may be employed. Such an FIB system includes an ion source column that directs an ion beam into a chamber that has a stage for supporting the workpiece; a pumping system that connects to the chamber to evacuate the interior of the chamber to a select pressure and to maintain an appropriately controlled pressure as necessary; an optional temperature control system to control the temperature of the reactant materials, the reactant handling system or the interior of the chamber; a gas delivery system connected in fluid communication to the interior of the chamber to introduce reactant gases into the interior of the chamber; a gas, vapor or fluid handling system to meter and control the flow of reactants and products introduced into the interior of the chamber or produced within the interior of the chamber by the processes of the invention.

Figure 1 illustrates one focused ion beam system 10 suitable for use in the present invention. System 10 includes an ion beam column 12 that has an ion source 14 and extractor electrode 16, and focusing elements 18 that produce a focused ion beam 20. System 10 further includes a chamber 22 that has a stage 24, two deposition nozzles 28A and 28B, motorized valves 34A and 34B, pressure transducers 35A and 35B, reservoirs 32A and 32B, exhaust port and pump 30 and a high vacuum pressure device such as a cold cathode ionization gauge 38 (CCIG). A workpiece 26 is disposed on stage 24 and positioned beneath the ion beam column 12. An optional charge neutralizer 36 is disposed within the chamber 22 and positioned above the workpiece 26 and directed at the open surface of the workpiece 26.

In the illustrated embodiment, system 10 includes a conventional ion column 12 that has a liquid metal ion source or gas field ion source 14 positioned above an extraction electrode 16 which draws off charged particles from the ion source 14. The drawn off particles pass by the focusing elements 18 that focus the drawn off particles into a finely focused beam of ions 20. In the illustrated embodiment, deflection electrodes 19 are disposed beneath the focusing elements 18. The deflection elements 19 operate to deflect the ion beam and thereby scan the ion beam across the surface of the workpiece 26. Ion columns such as the illustrated ion column 12 are well known in the art of focused ion beam workstations and any conventional ion column that can generate a beam of particles suitable for effecting deposition of the dielectric film can be employed with the present invention. One such ion column suitable for use with the present invention is the gallium liquid metal ion column, produced and sold by the Micron Coφoration of Massachusetts with the focused ion beam workstation Series 8000, 9800, 9000 and 2000. The illustrated chamber 22 is a vacuum chamber that sits beneath the ion column

12 and holds the workpiece 26 on stage 24 so that the ion beam can operate on the upper surface of the workpiece 26. Typically the chamber 22 includes a transport and delivery system for maintaining a vacuum seal while delivering the workpiece 26 into the chamber 22 . Furthermore, the chamber 22 typically includes a removable stage element 24 that moves in three dimensions within the chamber 22. Such a stage element allows the workpiece 24 to be positioned with a great degree of precision within the chamber 22. Typically chamber element 22 includes optional detector elements for detecting either secondary ions, secondary electrons or other such particles that are produced during focused ion beam processing of workpieces. The chamber 22 can be any conventional chamber suitable for use with a focused ion beam workstation. One such chamber is the chamber sold by the Micrion Corporation of Peabody, Massachusetts with the above-noted focused ion beam workstations.

The illustrated system 10 includes one preferred gas delivery system that includes two reservoirs 32 A and 32B that connect to separate injection elements 28 A and 28B that are disposed within chamber 22. Each reservoir 32 connects via a separate conduit to a separate deposition nozzle 28. Such an arrangement prevents intermixing of reactant materials before introduction of the materials into the chamber 22 and allows for greater control for varying the ratios of reactant materials employed during different applications. This advantageously prevents the reaction of materials prior to introduction into chamber 22. It should be obvious to one of ordinary skill in the art of focused ion beam deposition processes that the illustrated gas delivery system can include additional reservoirs providing additional reactant materials, carrying gases, or other materials into the interior of chamber 22. At the end of each delivery conduit 29A and 29B is an deposition nozzle 28 A and 28B. The deposition nozzle 28 A and 28B can be conventional deposition nozzles suitable for directing reactant gases onto the surface of the workpiece 26. In a preferred embodiment of the invention, as will be explained in greater detail hereinafter, each deposition nozzle 28A and 28B are coupled together to form a two-headed nozzle that provides a consistent flow of gases onto the surface of the workpiece 26. The construction of such nozzles is well known in the art of focused ion beam deposition techniques and the substitution of the nozzles described herein for other suitable nozzle configurations does not depart from the scope of the present invention. Figure 1 depicts two similar reactant material delivery systems. For clarity, only one will be described. The first reactant handling system comprises the reservoir 32A coupled into fluid communication to the proximal end of a delivery conduit 29A, that connects into one end of the motorized valve element 34A which controls material delivery responsive to a control signal generated by the pressure transducer 35A, by limiting or restricting the flow of reactant material from the reservoir 32A to the nozzle 28A.

As further shown by Figure 1 , the depicted reactant material handling system includes a feedback pressure control system that includes the pressure transducer 35 A, that connects in fluid communication to the side of the conduct 29A opposite to the reservoir 32A. As also depicted, the pressure transducer 35A connects to the motorized valve 34A. A control element in the valve 34A reads a control signal from the transducer 35 A, and adjusts the valve setting appropriately to adjust the flow of reactant material. In one embodiment the control signal directs the motorized valve to increase or decrease the flow of reactant material, and is generated by the transducer 35 A as a function of the pressure in conduit 29A detected by a manometer in transducer 35A. As configured, the pressure transducer 35A and the valve 34 A form a feedback control mechanism that monitors and controls the pressure of the reactant material in conduit 29A. Accordingly, the depicted reactant material handling system provides an independent, automatic, pressure control system for each reactant material, thereby providing a system that allows for controlled variation in the mixing ratios of the reactant materials.

Evacuation of the chamber 22 is possible through a conventional pumping stack 30 connected to the interior of chamber 22. The pumping stack 30 can consist of two pumping packages, where the first is a turbo molecular pump and the second is a rotary pump. The pumping stack 30 may also be isolated from the chamber 22 by a high vacuum gate valve of the type normally used with such pumping stacks. The turbo molecular pump based package ensures high vacuum pressure in the chamber 22 A high vacuum load lock system (not shown) is used for transporting loading of the workpiece 26 into and out of the interior of chamber 22.. It will be apparent to one of ordinary skill in the art that any suitable pumping system for evacuating the chamber 22 can be employed with the present invention.

In the illustrated embodiment, reservoir 32a contains a silicon-containing reactant material for depositing a silicon-containing dielectric film, such as silicon dioxide, onto the surface of the workpiece 26. A preferred silicon-containing dielectric film is silicon dioxide. The silicon-containing reactant material can be any reactant material that includes, in the skeleton of the composition, silicon atoms. As the skilled artisan will appreciate, the silicon-containing reactant is selected to permit deposition of a desired silicon-containing dielectric. In a preferred embodiment of the invention, the silicon-containing reactant material comprises a siloxane compound. As the term is used herein, a siloxane is any compound that includes within its skeletal structure silicon and oxygen atoms, and can be represented by one formula as:

(R - O-)_n - Si - (R')₄__n

wherein each R and R' can comprise, independently for each occurrence, hydrogen, lower alkyl, lower alkenyl, lower alkoxy, phenyl, or silyl; and n can be an integer from 1 to 4; or, where n can be at least 2, (R-O)2- taken together with the silicon atom to which they are attached, form a cyclosiloxane. In some preferred embodiments, R' is lower alkyl, more preferably methyl. In certain preferred embodiments, n is 2 and each R' is selected from the group consisting of hydrogen and methyl. Preferred siloxanes are cyclosiloxanes. One preferred siloxane is tetramethylcyclotetrasiloxane, which can be represented by the formula:

It will be apparent to one of ordinary skill in the art of film deposition that other siloxane-containing materials may be substituted for TMCTS, including tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), trisiloxane, vinylpentamethyldisiloxane, and other similar compounds, or mixtures thereof. Suitable materials or materials for forming suitable materials can be purchased from the Gelset Company of Tullytown Pennsylvania, among other suppliers. Reservoir 32A can also contain other reactant materials for aiding in the delivery of the silicon-containing reactant material. Similarly, reservoir 32A can connect to an alternative gas delivery system that includes a system for injecting carrying gas to carry the silicon-containing material through the injection conduit 29A and into the interior of the chamber 22. In a preferred embodiment of the invention the gas delivery system includes a thermal control element, such as an electric heating element disposed in thermal contact with the conduit 29A, that maintains the silicon-containing material at a temperature that is a sufficiently low, relative to room temperature, to prevent the silicon-containing material from condensing within the gas delivery conduits 29. For TMCTS, the thermal control element preferably maintains the TMCTS reactant material at a temperature that is about 5°- 10° F below the temperature of the room. The delivery system for the water-containing reactant material can similarly include such a thermal control element. In the illustrated embodiment, reservoir 32B contains a water-containing reactant material for depositing a dielectric film on the surface of a workpiece. In a preferred embodiment of the invention, reservoir 32B contains water maintained at room temperature. In operation, the in-line needle valve 34B is opened and the water in the reservoir is placed into fluid communication with the evacuated interior portion of chamber 22. The pressure differential between the pressure at the water reservoir and the pressure within chamber 22 causes a vapor flow of the water-containing material. Accordingly, the water-containing material travels down conduit 29B and passes through deposition nozzle 28B to enter into the interior of chamber 22.

Figure 2 illustrates one practice for operating an FIB system, such as system 10 for depositing a rectangular pad of dielectric film. Figure 2 depicts a process that rasters the ion beam at discrete positions of the substrate surface 26. Although an analog raster process could be employed, this digital raster is a preferred practice. As depicted by Figure 2, the ion beam 20 strikes the substrate surface 26 at a select location 40 and directs ions to the surface of the substrate 26 for a given dwell period. After the predetermined dwell period, the ion beam moves to the subsequent location 44, which is displaced from the location 40 by a pixel spacing distance 42 that preferably approximates the size of the beam 20 at the surface 26. This stepping or pitch provides for dielectric films with smooth surface topographies. As further depicted by Figure 2 the ion beam 20 rasters through the full set of deposition locations until a first pass is complete. Before commencing a second pass across the surface of substrate 26, the system waits a refresh period. The refresh period allows the concentration of reactant materials at the surface to reach acceptable levels, before the ion beam again begins to deposit materials. The system continues to make passes across the substrate 26 until the full dose, i.e., amount of charge per unit area, has been delivered. The number of passes necessary can be determined by comparing the size of the deposition film against the total beam dose, the charge delivery rate of the ion beam and the dwell times of the beam. Such a determination is within the scope of one of ordinary skill in the art of particle beam induced deposition techniques.

In one practice of the deposition process illustrated as Figure 2, the deposition nozzles 28A and B are formed together into two jet elements each fed from a separate one of the two conduits that each enter from the same side of the chamber 22. Each jet element is in fluid communication with the source of reactant material supplied through the respective deposition nozzle 28. In one embodiment, each jet element is a hollow tubular element with an inner diameter of approximately 5-25 mils. Tests have established that any jet element with an inner diameter of approximately 20 mils ± 5 mils performs well with the present invention. The nozzles are disposed above the workpiece 26 for providing reactant material to the surface of the workpiece during the deposition process. In a preferred practice of the invention, each deposition nozzle 28 is positioned approximately 50-700 microns, preferably 300-400 microns, from the center of the beam and 2-16 mils, preferably 8-12 mils, above the surface of the workpiece 26. Experimental tests have illustrated that an xy position in the range of 50-700 microns from the center of the ion beam deposits dielectric films with excellent properties of transmissivity and resistivity. Although Figure 2 depicts one preferred practice of the present invention, it should be obvious to one of ordinary skill in the art of thin film deposition that other processes and deposition nozzle configurations can be practiced with the present invention without departing from the scope thereof. It will also be noted that the delivery pressures noted herein are for systems that employ the nozzle and jet elements described above. It will be apparent to one of ordinary skill in the art of particle beam deposition that delivery pressures can vary dependent upon the size of the delivery nozzles. Moreover, it will be apparent to one of ordinary skill in this art that pressures vary dynamically during the deposition process, particularly at the surface of the substrate. Similarly, it should be obvious to one of ordinary skill that the deposition nozzles 28 can be placed in alternative positions and dispositions to the surface of the workpiece 26 during the deposition process and the structure of the deposition nozzle 28 and the positioning of the deposition nozzle 28 relative to the surface of the workpiece 26 is to be adapted for the particular energy source employed, whether ion beam, x-ray, electron beam, UV or other energy form. Processes according to the invention can now be described with reference to

Figure 3 which depicts a process for deposition of a dielectric material for purposes of modifying an integrated circuit. Figure 3 illustrates a focused ion beam of 50 that has milled through a first aluminum wire 52 to expose a second aluminum wire 54 that is positioned beneath the first aluminum wire 52. Figure 3B depicts the deposition of a dielectric material 60. As shown in Figure 3B, the deposition nozzles 28 are disposed proximate to the surface of the integrated circuit. Each nozzle 28 introduces reactant material proximate to the site of circuit modification and proximate to the center of the incident focused ion beam 50. As illustrated by Figure 3B a dielectric film 60 forms within the via milled through the aluminum wire 52. Figure 3 depicts a further step of the process that employs FIB 50 to mill through the dielectric film 60 to form a via to the underlying aluminum wire 54. A final step is depicted in Figure 3D that shows deposition nozzle 36 disposed above the via milled through the dielectric film 60. The nozzle 36 of Figure 3D connects in fluid communication to a source or sources of reactant materials suitable for effecting the focused ion beam deposition of a conducting material, for example, tungsten. Accordingly, Figure 3D illustrates the deposition of a conducting material 62 that connects to aluminum wire 54, passes through the via milled through the dielectric film 60 and forms a conductive pad at the surface of the integrated circuit. Such a conducting pad is useful for forming a surface contact that can be probed during testing of the integrated circuit. The deposited insulator prevents metal deposit 62 from shorting to aluminum wire 52. Processes of the invention will now be described with reference to certain exemplary practices.

Example 1

Preparation of Si0₂ Films By FIB Deposition Using TMCTS (C₄Hι₆S-4θ₂) and H₂O.

FIB induced deposition of a silicon dioxide film was carried out using a FIB workstation as depicted in Figure 1 equipped with deposition nozzles as described herein. Specifically, the FIB workstation was a Micrion 9100, manufactured and sold by the Micrion Corporation, Peabody, Massachusetts. The silicon-containing reactant material was TMCTS and the water-containing reactant material was water. The TMCTS is commercially available from the J.C. Schumacher Corporation, a unit of Air Products and Chemicals Inc., under the trade name "TOMCATS". The reservoir 32A holds the TMCTS liquid at 5-10° F below room temperature. This cooling aids in preventing TMCTS vapor from condensing within the conduit 29A or the deposition nozzle 28A. The reservoir 32A maintains the TMCTS at 3-5 torr absolute. The chamber 22 is evacuated to approximately 1 x lO'^torr- The conduit 29A and nozzle 28 form a fluid path between the reservoir and the interior portion of chamber 22. The motorized valve 34A and pressure transducer 35 A are disposed within this fluid path and control the flow of siloxane by allowing the feedback control system of the transducer 35A and motorized valve 34 to control the flow of reactant material. By opening the valve 34A, the pressure differential between the reservoir 32A and the interior portion of the chamber causes a vapor flow of siloxane to travel through conduit 29A and into the chamber 22. No carrying gases were employed.

The ion beam column 12 generated a 30kV focused ion beam and operated under the following conditions: Beam Current = 500pA (focused to a 0.15μm diameter spot size) Pixel Spacing 0.15 μm (di gital raster) ; Refresh Time = 4000μs (minimal time before beam returns to a pixel location);

Dwell Time = .5μs (time that beam stays at one pixel location before moving); and

Total Beam Dose InC/μm².

The siloxane was introduced at a pressure of .5T as measured at the transducer

35A at the delivery system. The H2O was introduced at six pressure levels between 0 and 3T. These pressures, and the resulting films, are given in Table 1. The resulting films are depicted in Figure 4.

H2O Pressure (as measured at (Max pt) (Avg.) transducer 35B) Film Thickness A Thickness A

OT 1 3108 3108

. 25T 2 4275 4273

. 5T 3 4712 4535

LOT 4 5035 4532

2.0T 5 4850 4505

3.0T 6 5267 4698

At 3T the pressure inside the chamber 22 rose to 2 x 10"6 torr as measured by the CCIG 38. Each film was deposited as approximately a 15μm by lOμm rectangular box.

The workpiece 26 introduced into the chamber 22 was a quartz photomask. The photomask was quartz introduced into the chamber 22 by normal operation of the FIB workstation, which includes a high vacuum load lock system. The photomask was seated on the stage 24 and disposed under the center of the ion column 24.

The resulting Siθ2 films were continuous, and had resistivities greater than or equal to 0.5MΩ cm depending upon reactant ratios. As depicted by Figure 4, the optical transmissivity from observations of the film increased with the pressure of the H2O. Pressures of H2O between about 2 and 3 torr provided films with superior optical transmissivity. Pressures of H2O less than 2 torr provided darker films with lower resistivity.

The deposition yield of deposited material for each gallium ion delivered appeared excellent as films grew 7-10 times faster than tungsten films for tungsten hexa carbonyl under similar process conditions. Example 2

Preparation of Siθ2 Films By FIB Deposition Using TMCTS (C4H 16Si θ₂) and H2O.

Similarly, a second set of films were deposited using a FIB workstation as depicted in Figure 2 equipped with deposition nozzles as described above. Again, the silicon-containing reactant material was TMCTS and the water-containing reactant material was water. For these films siloxane was introduced into the chamber 22 at a pressure of .2T measured at the transducer 35 A. The reservoir 32 A holds the TMCTS at 5-10° F below room temperature. This cooling aids in preventing TMCTS vapor from condensing within the conduit 29A or the deposition nozzle 28A. The chamber 22 is evacuated to approximately 1 x 10"" torr measured at the CCIG 38- The conduit 29A and nozzle 28A form a fluid path between the reservoir and the interior portion of chamber 22. The motorized valve 34 A and transducer 35 A are disposed within this fluid path and control the flow of siloxane. By opening the valve 34A, the pressure differential between the reservoir 32 A and the interior portion of the chamber causes a vapor flow of siloxane to travel through conduit 29A and into the chamber 22. The delivery system feedback mechanism maintains the selected pressures No carrying gases were employed.

The ion beam column 12 generated a 30kV focused ion beam and operated under the following conditions:

Beam Current - 500pA (focused to a 0.15μm diameter spot size);

Pixel Spacing = 0.15μm;

Refresh Time = 4000μs;

Dwell Time = .5μs; and Total Beam Dose = InC/μm².

The siloxane was introduced at a pressure of .2T at the transducer 35A. Again, the H2O was introduced at six pressure levels between 0 and 3T as measured at the transducer 35B. These pressures, and the resulting films, are given in Table 2. The resulting films are depicted in Figure 5. H2O Pressure (as measured at (Max pt) (Avg.) transducer 35B) Film Thickness A Thickness A

OT 1 4308 4249

. 25T 2 4481 4416

.5T 3 4704 4550

LOT 4 4869 4462

2.0T 5 5136 4374

3.0T 6 5721 4944

At 3T the pressure inside the chamber 22 rose to 2 x 10^*6 torr measured at the CCIG 38. Each film was deposited as approximately a 15μm by lOμm rectangular box.

The workpiece 26 introduced into the chamber 22 was a quartz photomask. The photomask was seated on the stage 24 and disposed under the center of the ion column 24.

The resulting Siθ2 films were continuous, and had resistivities that were greater than or equal to 0.5MΩ cm. As depicted by Figure 4, the optical transmissivity of the film increased with the pressure of the H2O. Pressures of H2O between about 2 and 3 torr provided films with superior optical transmissivity. Pressures of H2O less than 2 torr provided darker films with lower resistivity.

The deposition yield of deposited material for each gallium ion delivered appeared excellent as films grew 7-10 times faster than tungsten films for tungsten hexa carbonyl under similar process conditions.

Example 3

Preparation of S1O2 Films By FIB Deposition Using TEOS and H₂O.

In a third series of depositions, silicon oxide films were deposited using a focused ion beam workstation with introduction of H O and TEOS.

Deposition 1 Beam Current 300pA (focused to a 0.10 μm diameter spot size);

Pixel Spacing 0.1 Oμm; Dwell Time 0.2μs; Refresh Time 4000μs; Total Beam Dose 0.6 nC/μm² Beam 300 pa TEOS Pressure = 0.500 torr H2O Pressure = 3.500 ton-

Deposition Thickness= 21 OOA

Deposition 2

Beam Current = 300pA (focused to a 0.1 Oμm diameter spot size);

Pixel Spacing = 0.1 Oμm; Dwell Time = 0.2μs;

Refresh Time = 4000μs;

Total Beam Dose = 1.2 nC/μm²

TEOS pressure = 0.500 torr

H₂0 = 3.500 ton-

Deposition Thickness = 4300A

Resistivity measurements were performed and no current draw was observed across the deposited pads. A maximum of 25 volts was applied. Two more depositions were done with doses of 0.30 nC/μm² and 0.15 nC/μm² to obtain thinner deposits.

These were measured at 1200A and 700A. Again, up to 25 volts was applied across the pads without any current draw observed.

In a further preferred embodiment of the invention for the deposition of dielectric films upon the surface of a substrate 26 wherein the substrate is an insulator or dielectric material, such in the case of a phase mask, the system employs the charge neutralizer 36 to neutralize charge build up at the surface of the substrate 26. In one embodiment of the invention the charge neutralizer 36 is an electron flood gun for generating a beam of electrons at an energy of between approximately 100 and 1000 V and preferably at about 500 eV. One such electron flood gun is a flood gun manufactured by the Kimball Physics Company of New Hampshire. However, any charge neutralization technique suitable for reducing charge at the substrate surface may be practiced with the invention without departing from the scope thereof.

During operation the electron gun charge neutralizer element 36 directs a beam of electrons to the point at which the ion beam 20 is impinging at the surface of substrate 26. Such an operation allows the electrons generated by the charge neutralizer 36 to prevent the charge build-up caused, in part, by the implantation of positive gallium ions and the emission of secondary electrons from the surface of substrate 26. The charge neutralization prevents defocusing of the ion beam and unwanted shifting of the ion beam, thereby allowing the process according to the invention to deposit dielectric materials with greater precision. It has been noted that this is particularly important during the filling of voids in a phase shift mask, particularly voids having high aspect ratios as the ion beam must not defocus or blur while traveling into the void. Further, the charge neutralization improves deposition rates by allowing the use of larger particle beam currents which provide better deposition yield. Moreover, during the filling of voids, the system 10 depicted in Figure 1, which includes separate delivery systems for each reactant material, allows independent control and fine adjustment of deliveries of reactant materials to generate dielectric films of high quality. By controlling independently the delivery of each reactant material, system 10 allows for controlling the ratios of the two reactant materials. By controlling the ratios of reactant materials during a deposition process, proper ratios can be empirically determined which allow for filling holes without forming voids which can occur if the top portion of a hole is filled with dielectric material before the lower portion of the hole is completely filled.

The films generated by the present invention provide improved UV transmissivity. It is understood that gallium and carbon film contamination have a deleterious effect on ultraviolet radiation transmission. Both carbon and gallium can discolor the film, with gallium causing ion staining of the dielectric material. Systems and methods according to the invention are understood to reduce ion staining by providing higher deposition rates and greater deposition yields per gallium ion. Moreover, by reducing the contamination of gallium within the deposition films, it is understood that improved material resistivity properties are achieved by reducing the metallic components within the film.

UV transmissivity has been measured by microdensitometers such as the Zeiss microdensitometer to show the films have improved transmissivity in the UV spectrum. Moreover, visual observation of the generated dielectric films show improved transmissivity of white light, which is generally understood as light in the range of 400- 700 nm. Such white light transmissivity is depicted in Figures 4 and 5.

As can be seen from the above description, the systems and methods according to the invention provide improved methods for depositing dielectric films, and provide dielectric films having improved properties of resistivity and transmissivity, among other improved properties. It will be appreciated by those skilled in the art of particle beam deposition techniques that changes can be made to the embodiments and processes described above without departing from the broad inventive concept thereof. It will further be understood therefore, that the invention is not to be limited to the particular embodiments disclosed herein but is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

Claims

We claim:

1. A method for depositing a dielectric material onto the surface of a workpiece, comprising the steps of providing a chamber having an interior portion with a stage element for holding said workpiece and having an injection element for introducing reactant material into said interior portion, introducing through said injection element a silicon-containing reactant material, introducing through said injection element a water-containing reactant material, and passing a particle beam through said interior portion and to said surface of said workpiece, for depositing said dielectric material thereon.

2. A method according to claim 1 , wherein said step of introducing said silicon- containing reactant material includes the step of introducing a siloxane-containing reactant material.

3. A method according to claim 1, wherein said step of introducing said silicon- containing reactant material includes the step of introducing TMCTS.

4. A method according to claim 2, wherein said step of introducing TMCTS includes the step of introducing TMCTS into said chamber to a pressure in a range of about 0.1-3.0 torr.

5. A method according to claim 1 , wherein said step of introducing silicon- containing reactant material includes the step of introducing TEOS.

6. A method according to claim 4, wherein said step of introducing TEOS includes the step of introducing TEOS into said chamber to a pressure in a range of about 0.1-3.0 torr.

7. A method according to claim 1 , wherein said step of introducing said water- containing reactant material includes the step of introducing water.

8. A method according to claim 6, wherein said step of introducing said water includes the step of introducing water into said chamber at a pressure in a range of about 0.5-6 torr.

9. A method according to claim 1, wherein said step of passing a particle beam includes passing an ion beam.

10. A method according to claim 9, wherein said step of passing an ion beam through said chamber interior portion includes the step of passing a 30kV ion beam.

1 1. A method according to claim 9, wherein said step of passing an ion beam through said chamber interior portion includes the step of passing a gallium ion beam.

12. A method according to claim 1 , wherein said step of passing a particle beam includes passing an electron beam.

13. A method according to claim 1 , wherein said step of providing a chamber having an injection element, includes the step of providing an injection element having at least two input nozzles.

14. A method according to claim 10, including the step of providing at least one of said input nozzles with two jet elements, and disposing at least one of said jet elements at a position between about 50-700 microns from the center of the particle beam.

15. A method according to claim 1 including the further step of delivering electrons to the surface of the workpiece for neutralizing charge at the surface.

16. A method according to claim 1 including the further step of directing a beam of electrons at the surface of the workpiece for neutralizing charge accumulating at the surface of the workpiece.

17. A method according to claim 1 including the further step of controlling a delivery pressure of said silicon-containing reactant material substantially independently from a delivery pressure of said water-containing reactant material.

18. A method for correcting a defect on a surface of a phase mask, comprising the steps of providing a chamber having an interior portion with a stage element for holding said phase mask and having an injection element for introducing reactant material into said interior portion, introducing through said injection element a silicon-containing reactant material, introducing through said injection element a water-containing reactant material, providing a source of electrons and providing said electrons said surface of said phase mask, and passing an ion beam through said interior portion and directed to said defect on said surface of said phase mask for correcting said defect.

19. A method according to claim 18 wherein said step of providing said source of electrons includes the step of providing an electron gun for generating a beam of electrons.

20. A system for depositing a dielectric material onto the surface of a workpiece, comprising a chamber having an interior portion with a stage element for holding said workpiece, an injection element for introducing reactant material into said interior portion, wherein said injection element includes a first delivery element for introducing a silicon- containing reactant material into said chamber and a second delivery element for introducing a water-containing reactant material into said chamber, and a source of a particle beam for passing a particle beam through said interior portion and to said surface of said workpiece, for depositing said dielectric material thereon.

21. A system according to claim 20 wherein said first delivery means includes feedback control means for controlling a delivery pressure of said silicon-containing reactant material.

22. A system according to claim 20 wherein said first delivery means includes feedback control means for controlling a delivery pressure of said water-containing reactant material.

23. A deposition film formed onto the surface of a workpiece by a process comprising the steps of providing a chamber having an interior portion with a stage element for holding said workpiece and having an injection element for introducing reactant material into said interior portion, introducing through said injection element a silicon-containing reactant material, introducing through said injection element a water-containing reactant material, and passing a particle beam through said interior portion and to said surface of said workpiece, for depositing material to form said deposition film.

24. A deposition film according to claim 23, wherein said step of introducing said silicon-containing reactant material includes the step of introducing a siloxane- containing reactant material.

25. A deposition film according to claim 23, wherein said step of introducing said silicon-containing reactant material includes the step of introducing TMCTS.

26. A deposition film according to claim 1, wherein said step of introducing said water-containing reactant material includes the step of introducing water.