CN103454861A - Overlay measuring mark and method - Google Patents
Overlay measuring mark and method Download PDFInfo
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- CN103454861A CN103454861A CN2012101814864A CN201210181486A CN103454861A CN 103454861 A CN103454861 A CN 103454861A CN 2012101814864 A CN2012101814864 A CN 2012101814864A CN 201210181486 A CN201210181486 A CN 201210181486A CN 103454861 A CN103454861 A CN 103454861A
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Abstract
The invention provides an overlay measuring mark. The mark is divided into a first region, a second region, a third region and a fourth region on an x-y surface and is provided with a plurality of medium layers on the z direction, wherein the first region and the second region have first grating structures, the second region and the third region have second grating structures, the fourth region does not have a grating structure, the first grating structure and the second grating structure are respectively located on different medium layers and have the same period, and the overlay error between the first grating structure and the second grating structure is d. By using the mark, the CD (Compact Disc) feature and the overlay error can be measured more easily and simultaneously.
Description
Technical field
The present invention relates to field of lithography, relate in particular to mark and method that alignment is measured.
Background technology
Along with constantly dwindling of semiconductor devices critical size, the especially introducing of Double patterning technology, make the requirement of alignment precision stricter.Take the 32nm technology node as example, and alignment precision is 5.7nm, and its measuring accuracy is generally 1/10 of alignment precision, i.e. 0.57nm.Traditional alignment measuring technique based on imaging more and more can not meet the demands aspect measurement accuracy, the skew particularly caused due to survey instrument (tool-induced shift, TIS) problem, make measuring uncertainty reach the magnitude of several nanometers, so must find the measurement means of a new alignment size.
A kind of alignment measuring method based on the scatterometry technology just progressively grows up, and is proved to be able to meet the accuracy requirement that under new technology node, alignment is measured.The method originates from utilizes scattering and diffraction to carry out the method that optics Critical Dimension measures, diffraction light by direct measuring unit marking is determined overlay error, measuring speed is fast, sampling area is little, substantially many error terms of traditional measurement method have been eliminated simultaneously, as positioning error, focal plane error, aberration factor and mechanical vibration etc., make it there is minimum TIS.Chinese patent application CN200510091733, all disclose such method in U.S. Patent application US2006/0285111 A1, US7173699B2, US2008/0018897 A1, US7477405 B2, WO2007/133755 A2, US7428060B2 and US6985232B2.
The method has been used strict Method of Physical Modeling in measuring process, see Formulation for stable and efficient implementation of the rigorous coupled-wave analysis of binary gratings, J. Opt. Soc. Am. A 12,1068-1076, try to achieve the alignment parameter by Converse solved method from the feature of diffraction light, and other a series of relevant technological parameters, as thickness, n, k value, CD, sidewall angle etc.Owing to having comprised some and the incoherent parameter of alignment in model, therefore on the measurement of overlay error, can be subject to the impact of other parameters, these parameters are generally determined by technological factor, may be some system deviations or stochastic error.In order to improve model accuracy, reduce the impact of these error components on measuring accuracy, need to find a kind of method of testing and measurement markers of optimization.
Summary of the invention
In order to overcome the above problems, the present invention proposes a kind of alignment measurement markers, the described x-y of being marked at face is divided into first to fourth zone, there is the multilayered medium layer on the z direction, wherein, the first and second zones have the first optical grating construction, the second and the 3rd zone has the second optical grating construction, the 4th zone does not have optical grating construction, the first optical grating construction and the second optical grating construction are respectively on different dielectric layers, the first optical grating construction and the second optical grating construction have the identical cycle, and overlay error between the two is d.
Wherein, described mark has four layers of dielectric layer, and described the first optical grating construction is positioned on the first medium layer, and the second optical grating construction is positioned on the 3rd dielectric layer.
Wherein, described first to fourth zone distributes in the x-direction.
Wherein, described first to fourth zone distributes in the y-direction.
The invention allows for the method for utilizing above-mentioned overlay mark to measure technological parameter, comprising:
The 4th zone is measured, according to measurement result, obtained the thickness of each dielectric layer and refractive index n, k;
Respectively the first and the 3rd zone is measured the first grating pattern parameter of calculating respectively first area according to thickness and the refractive index of measurement result and each dielectric layer and the second grating pattern parameter in the 3rd zone; And
Second area is measured, according to the thickness of measurement result and each dielectric layer and the pattern calculation of parameter overlay error d of refractive index and the first grating and the second grating.
Wherein, utilize scatterometer to be measured each zone.
Wherein, described scatterometer is spectral type scatterometer or angular resolution type scatterometer.
Wherein, utilize Converse solved method to calculate each parameter.
Wherein, described Converse solved method is non-linear regression method or library inquiry method.
Use mark of the present invention to measure CD pattern and overlay error by the scatterometry technology simultaneously.The CD pattern has comprised the photoetching agent pattern of pattern and this process layer after the etching of a upper process layer.Method of the present invention, by the technological parameter of each process layer of calibration, makes the alignment based on scatterometry measure the impact that is subject to technological factor still less, and measurement model is more accurate, thereby improves precision and the robustness of this class alignment measurement means.According to the characteristics of scatterometry algorithm, because the measurement of overlay error can utilize the result of CD topography measurement, make this measurement scheme on calculating more economically.
The accompanying drawing explanation
About the advantages and spirit of the present invention, can be further understood by following detailed Description Of The Invention and appended diagram.
Figure 1 shows that the schematic diagram of scatterometry;
Figure 2 shows that the mask mark of first embodiment of the invention and the schematic diagram of measurement markers;
Figure 3 shows that the schematic flow sheet of the measuring method of first embodiment of the invention;
Figure 4 shows that mask mark second embodiment of the invention and the schematic diagram of measurement markers.
Embodiment
Describe specific embodiments of the invention in detail below in conjunction with accompanying drawing.
The first embodiment
Figure 1 shows that the schematic diagram of scatterometry.Light source 11 sends detection light, and in the spectral type scatterometer, light source is generally white light source; In angular resolution type scatterometer, light source is generally monochromatic source, or the composite light source be comprised of some discrete spectral lines.Surveying light projects on sample 13 through surveying light path 12.Sample is generally periodic semiconductor figure, as the photoresist grating on silicon chip, or the groove after etching, hole array etc.These figures have comprised certain appearance structure 18, can pass through cycle (Pitch), Parameter H T(height), the SWA(sidewall angle) and Mid-CD(in the middle of live width) etc. sign, the purpose of scatterometry is these parameters of mensuration.Survey light after the sample reflect/scatter, measured light path 14 is collected, and the reflect/scatter light of collecting finally is projected onto detector 15 and measures.In the spectral type scatterometer, detector is generally spectrometer, records catoptrical spectral line result 17, and detector face is positioned at the image planes of optical path; In angular resolution type scatterometer, detector is generally two-dimensional array sensor, as CCD, CMOS etc., records reflected light in incident angle
and position angle
on distribution situation 16, detector is positioned at the pupil face of optical path.By the scattered light information recorded, can obtain by Converse solved method the pattern parameter of sample, Converse solved method can be non-linear regression method, or the library inquiry method.
In traditional overlay error measuring method based on model, overlay error is included in the model of the whole film of description system as a pattern parameter, then by the contrary method of asking, obtains this parameter.The undetermined parameter that comprises other in model parameter due to the method, such as the CD(live width), the SWA(sidewall angle) etc., measuring-signal may be insensitive to overlay error in this case, perhaps between overlay error and other model parameters, can form and crosstalk etc., affect the measuring accuracy of overlay error.And, because the undetermined parameter of whole film system is more, computation process can expend long time.In the alignment measurement scheme based on experience, need to use a plurality of measurement markers, be marked at the space occupied on whole silicon chip larger; And the pattern asymmetry of grating marker itself can affect the accuracy of measurement result.
The present invention proposes for these problems a kind of mark and the method that alignment is measured, make by the scatterometry technology and can measure CD pattern and overlay error simultaneously, and can improve measuring accuracy and the speed of overlay error.
Shown in Fig. 2, be the mask mark of first embodiment of the invention and the schematic diagram of measurement markers.A, the B zone of the optical grating construction of first mask mark 21 in this mark; B, the C zone of the optical grating construction of second mask mark 22 in this mark.
Below illustrate the manufacturing process of measurement markers on silicon chip: at first on silicon base, deposit (in the present embodiment, all deposition procedures all can adopt the technique realizations such as plating) one deck uniform dielectric (SiN, SiO2 etc.); On this layer of medium, deposition one deck new medium (fluorine silex glass etc.), then be coated with one deck photoresist, with mask mark 22 exposed, etching, the center section of this process layer is optical grating construction, both sides are uniform dielectric; Continuation deposits one deck uniform dielectric (bottom anti-reflection layer etc.) on this process layer; Finally on this medium, be coated with one deck photoresist, with mask mark 21, exposed, half zone of this process layer is the photoresist grating structure, and second half is even photoetching glue medium, and wherein photoresist grating zone and film are that the etched diffraction grating zone of the 3rd layer has overlapping part in the x direction.This four layer series has formed the measurement markers of the present embodiment.
In figure, 23,24,25,26 is respectively the sectional view that A, B, C, D zone film tie up to the y direction, and film is that 23 ground floors are photoresist grating structures, and other layer is uniform dielectric; Film is that 24 ground floors and the 3rd layer are optical grating constructions, and other layer is uniform dielectric, and there is a side-play amount d position of upper and lower two-layer grating, has reflected overlay error; It is the etched diffraction grating structure that film is 25 the 3rd layers, and other layer is uniform dielectric; Film is that 26 each layers are all uniform dielectric.
In order to improve the sensitivity of measurement, the initial offset that ground floor grating and the 3rd layer of grating can be set was 1/4 cycle;
Measuring process as shown in Figure 3.At first, by scatterometer or other measuring equipments, (as shown in mark in Fig. 3 41) measured in the D zone, obtained the thickness of each tunic system according to measurement result, n, k value, wherein n means refractive index, k means extinction coefficient (as shown in Fig. 3 42).
Utilize scatterometer to be measured (as shown in Fig. 3 43) to the C zone.Suppose by three parameters: live width (CD_3), highly (Height_3) and side wall angle (SWA_3) are described the shape characteristic of the 3rd layer of grating, thickness and the refractive index of each tunic system of obtaining in 41,42 are calculated for model, and the Converse solved program of measuring-signal substitution of scatterometer is solved, obtain the pattern parameters C D_3, Height_3, SWA_3(of the 3rd layer of grid stroke as shown in Fig. 3 44).Measurement mechanism can be the spectral type scatterometer, or angular resolution type scatterometer; Converse solved method can be non-linear regression method, or the library inquiry method.
Utilize scatterometer to be measured (as shown in Fig. 3 45) to a-quadrant.Equally by three parameters: live width (CD_1), highly (Height_1) and side wall angle (SWA_1) are described the shape characteristic of ground floor grating, thickness and the refractive index of each tunic system of obtaining in 41,42 are calculated for model, and the Converse solved program of measuring-signal substitution is solved, the pattern parameters C D_1 of acquisition ground floor grid stroke, Height_1, SWA_1(are as shown in Fig. 3 46).Measurement mechanism, method and 43,44 identical.
Utilize scatterometer to be measured (as shown in Fig. 3 47) to the B zone.Represent the side-play amount of upper and lower two-layer grating by parameter d, it is overlay error, the pattern parameter (CD_1, Height_1, SWA_1 and CD_3, Height_3, SWA_3) of the thickness of each tunic system that step 41-46 is obtained and refractive index, grid stroke is calculated for model, and the Converse solved program of measuring-signal substitution is solved, obtain overlay error d(as shown in Fig. 3 48).
Due in measuring process 41-46 the parameter to each process layer calibrated, overlay error becomes unique parameter undetermined, so will improve its measuring accuracy; And, due to the minimizing of model undetermined parameter, significantly reduce computing time.Suppose to describe by 7 parameters (CD_1, Height_1, SWA_1, CD_3, Height_3, SWA_3 and d) model that this alignment is measured, each parameter value number in its variation range is N, and traditional alignment measuring method based on model is proportional to 7 powers of N computing time; If adopt improved measuring method, be proportional to 3 powers of N computing time, so be only 1/ original N computing time
4.
Wherein measuring process 43,44 and 45,46 convertible order.
The second embodiment
Present embodiment changes the design of measurement markers on the basis of the first embodiment, as shown in Figure 4.Measurement markers has different film system in the x direction, the zones of A, B in figure, C, D are corresponding respectively four kinds of different films systems.First mask mark 51, in the first process layer exposure, forming optical grating construction, second mask mark 52, in the 3rd process layer exposure, forming optical grating construction, there is overlapping part in this layer of grating region and ground floor photoresist grating zone in the x direction.The 53rd, whole measurement markers is at the sectional view of y direction.Mark in this measurement markers and the first embodiment can be placed in marking groove different on silicon chip.
To identical in the measuring process of CD pattern and overlay error and the first embodiment, at first the D zone is measured, obtain the thickness of each tunic system, n, k value (refractive index); Secondly A and C zone are measured, obtained the shape characteristic of ground floor photoresist grating and the 3rd layer of etched diffraction grating line; Finally, to B area side amount, obtain overlay error d, utilizing the film recorded in measuring process is parameter and grating shape characteristic.
Described in this instructions is preferred embodiment of the present invention, and above embodiment is only in order to illustrate technical scheme of the present invention but not limitation of the present invention.All those skilled in the art, all should be within the scope of the present invention under this invention's idea by the available technical scheme of logical analysis, reasoning, or a limited experiment.
Claims (9)
1. an alignment measurement markers, the described x-y of being marked at face is divided into first to fourth zone, there is the multilayered medium layer on the z direction, wherein, the first and second zones have the first optical grating construction, and the second and the 3rd zone has the second optical grating construction, the 4th zone does not have optical grating construction, the first optical grating construction and the second optical grating construction are respectively on different dielectric layers, and the first optical grating construction and the second optical grating construction have the identical cycle, and overlay error between the two is d.
2. mark according to claim 1, wherein, described mark has four layers of dielectric layer, and described the first optical grating construction is positioned on the first medium layer, and the second optical grating construction is positioned on the 3rd dielectric layer.
3. mark according to claim 1, wherein, described first to fourth zone distributes in the x-direction.
4. mark according to claim 1, wherein, described first to fourth zone distributes in the y-direction.
5. utilize the method for any one described overlay mark measurement technological parameter in claim 1-4, comprising:
The 4th zone is measured, according to measurement result, obtained the thickness of each dielectric layer and refractive index n, k;
Respectively the first and the 3rd zone is measured the first grating pattern parameter of calculating respectively first area according to thickness and the refractive index of measurement result and each dielectric layer and the second grating pattern parameter in the 3rd zone; And
Second area is measured, according to the thickness of measurement result and each dielectric layer and the pattern calculation of parameter overlay error d of refractive index and the first grating and the second grating.
6. method according to claim 5, wherein, utilize scatterometer to be measured each zone.
7. method according to claim 6, wherein, described scatterometer is spectral type scatterometer or angular resolution type scatterometer.
8. method according to claim 5, wherein, utilize Converse solved method to calculate each parameter.
9. method according to claim 8, wherein, described Converse solved method is non-linear regression method or library inquiry method.
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| CN201210181486.4A CN103454861B (en) | 2012-06-05 | 2012-06-05 | The mark that a kind of alignment is measured and method |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108292103A (en) * | 2015-09-30 | 2018-07-17 | Asml荷兰有限公司 | Metering method, target and substrate |
| WO2021072794A1 (en) * | 2019-10-18 | 2021-04-22 | 南京诚芯集成电路技术研究院有限公司 | Method and system for evaluating process quality of inverted trapezoidal or t-shaped structure |
| CN114326313A (en) * | 2020-09-29 | 2022-04-12 | 长鑫存储技术有限公司 | Method for simultaneously monitoring multiple lighting conditions |
| CN117289562A (en) * | 2023-11-22 | 2023-12-26 | 全芯智造技术有限公司 | Method, apparatus and medium for simulating overlay marks |
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| WO2002065545A2 (en) * | 2001-02-12 | 2002-08-22 | Sensys Instruments Corporation | Overlay alignment metrology using diffraction gratings |
| US20050122516A1 (en) * | 2002-07-03 | 2005-06-09 | Abdurrahman Sezginer | Overlay metrology method and apparatus using more than one grating per measurement direction |
| US20050195398A1 (en) * | 2002-12-05 | 2005-09-08 | Kla-Tencor Technologies Corporation | Continuously varying offset mark and methods of determining overlay |
| CN1916603A (en) * | 2004-08-16 | 2007-02-21 | Asml荷兰有限公司 | Method and apparatus for angular-resolved spectroscopic lithography characterisation |
| CN101114135A (en) * | 2007-07-24 | 2008-01-30 | 上海微电子装备有限公司 | Aligning system photolithography equipment |
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Patent Citations (5)
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| WO2002065545A2 (en) * | 2001-02-12 | 2002-08-22 | Sensys Instruments Corporation | Overlay alignment metrology using diffraction gratings |
| US20050122516A1 (en) * | 2002-07-03 | 2005-06-09 | Abdurrahman Sezginer | Overlay metrology method and apparatus using more than one grating per measurement direction |
| US20050195398A1 (en) * | 2002-12-05 | 2005-09-08 | Kla-Tencor Technologies Corporation | Continuously varying offset mark and methods of determining overlay |
| CN1916603A (en) * | 2004-08-16 | 2007-02-21 | Asml荷兰有限公司 | Method and apparatus for angular-resolved spectroscopic lithography characterisation |
| CN101114135A (en) * | 2007-07-24 | 2008-01-30 | 上海微电子装备有限公司 | Aligning system photolithography equipment |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108292103A (en) * | 2015-09-30 | 2018-07-17 | Asml荷兰有限公司 | Metering method, target and substrate |
| WO2021072794A1 (en) * | 2019-10-18 | 2021-04-22 | 南京诚芯集成电路技术研究院有限公司 | Method and system for evaluating process quality of inverted trapezoidal or t-shaped structure |
| CN114326313A (en) * | 2020-09-29 | 2022-04-12 | 长鑫存储技术有限公司 | Method for simultaneously monitoring multiple lighting conditions |
| CN114326313B (en) * | 2020-09-29 | 2024-01-23 | 长鑫存储技术有限公司 | Method for simultaneously monitoring multiple lighting conditions |
| CN117289562A (en) * | 2023-11-22 | 2023-12-26 | 全芯智造技术有限公司 | Method, apparatus and medium for simulating overlay marks |
| CN117289562B (en) * | 2023-11-22 | 2024-02-13 | 全芯智造技术有限公司 | Method, apparatus and medium for simulating overlay marks |
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Address after: 201203 Shanghai Zhangjiang High Tech Park of Pudong New Area Zhang Road No. 1525 Patentee after: Shanghai microelectronics equipment (Group) Limited by Share Ltd Address before: 201203 Shanghai Zhangjiang High Tech Park of Pudong New Area Zhang Road No. 1525 Patentee before: Shanghai Micro Electronics Equipment Co., Ltd. |
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