Notice of Pre-AIA or AIA Status
The present application is being examined under the pre-AIA first to invent provisions.
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 01/27/2026 has been entered.
Priority
Current application, US Application No. 17/850,888 filed on 06/27/2022, is a Divisional of US Application No. 13/508,495, filed on 05/07/2012, which is a National Stage entry of PCT/US2012/032169, International Filing Date: 04/04/2012, which claims Priorities from US Provisional Application No. 61/598,140 filed on 02/13/2012, from US Provisional Application No. 61/597,504 filed on 02/10/2012, from US Provisional Application No. 61/509,842 filed on 07/20/2011, from US Provisional Application No. 61/474,167 filed on 04/11/2011 and from US Provisional Application No. 61472545 filed on 04/06/2011.
DETAILED ACTION
This office action is responsive to the amendment filed on 01/27/2026. Claims 1 and 3-8 are currently pending. Claims 2, 9-10 and 20 are canceled per applicant’s request and claims 11-19 are withdrawn per applicant’s election response to the restriction requirement.
Response to Amendment
Applicant's amendment is entered into further examination and appreciated by the examiner.
Response to Arguments/Remarks
Regarding remarks to the claim objections, amendment is accepted and the previous objections are withdrawn. As a side note, examiner notices applicant’s statement “Claims 2, 3, 8 and 9 are canceled” is incorrect and appears to mean “Claims 2, 9 and 10 are canceled” according to the latest amendment.
Regarding remarks to the rejections under 35 USC 112(a) and 112(b), amendment is accepted and the previous rejections are withdrawn.
Regarding arguments on the rejections under 35 USC 101, amendment accompanied with applicant’s persuasive arguments is accepted and the previous rejections are withdrawn.
The limitations “each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers based on overlay metrology measurement signals associated with the plurality of metrology targets” and “controlling one or more process tools utilizing at least one of feedback or feedforward control based on the set of process correctables” are treated as additional elements by the examiner and they are significant elements and/or significant extra solution activities and indicate an integration of a practical application to the judicial exception. Therefore, claims 1 and 3-8 are patent eligible.
Regrading argument on the rejections under 35 USC 103 and Double Patenting, applicant’s arguments have been considered but are moot in view of new ground of rejection necessitated by the amendment because the arguments do not apply to any of the references and/or office action being used in the current rejection.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1, 3 and 7 are rejected under 35 U.S.C. 103 as being unpatentable over Adel (US 20030223630 A1), hereinafter ‘Adel’ in view of Seligson (US 20040040003 A1), Adel (Adel, Mike, and et al. "Optimized overlay metrology marks: theory and experiment." IEEE Transactions on Semiconductor manufacturing 17, no. 2 (2004): 166-179). Hereinafter ‘Adel-NPL’ and Sullivan (Sullivan, Neal, and Jennifer Shin. "Overlay metrology: the systematic, the random and the ugly." In AIP Conference Proceedings, vol. 449, no. 1, pp. 502-512. American Institute of Physics, 1998), herein after ‘Sullivan’.
As per claim 1, Adel discloses
A computer-implemented method for providing a set of process tool correctables,(overlay method, correcting the overlay error … based on the calibration data [abs], process are modeled via computer programs [0061], determine the … tool correctible for overlay [0108]) comprising:
generating an overlay metrology result for each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers; (measure … product wafer [Fig. 3 26], measure patterns on wafer [Fig. 4 46])
generating a quality metric associated with each acquired overlay metrology result; (quantitative metrics for the quality, exposure tool illumination configuration, wavelength, numerical aperture and the geometry of the pattern, overlay metrology [0010], the overlay data contained in the calibration data, relationship … between process robust and device representing targets, a signature [0072, Fig. 3 28 30], metrics [0079], overlay metrology, metrics [0162])
However, Adel is silent regarding a quality metric for each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers based on overlay metrology measurement signals associated with the plurality of metrology targets, wherein the quality metric for a particular metrology target of the plurality of metrology targets is generated by applying multiple overlay algorithms to the overlay metrology measurement signals for the particular metrology target to generate an overlay estimate distribution and generating the quality metric based on a statistical property of the overlay estimate distribution.
Seligson discloses generating a quality metric for each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers based on overlay metrology measurement signals associated with the plurality of metrology targets (analyzing the quality of overlay targets [abs, 0005], quantitative metric on a quality of the overlay error [0008, 0056, claims 5 and 13], quality or confidence level [0058], wafer, lot [0082], overlay distribution [0094], diagnostic metric distribution on the wafer map [0108]),
wherein the quality metric for a particular metrology target of the plurality of metrology targets is generated by applying multiple overlay algorithms to the overlay metrology measurement signals for the particular metrology target to generate an overlay estimate distribution and generating the quality metric based on a statistical property of the overlay estimate distribution. (techniques or algorithms for measuring … a target [0046], measurement algorithm [0048], characterizing noise data … algorithms [0049, claim 4], target diagnostic, quality or confidence level, targets, algorithms [0058], distribution [0076, 0078], algorithms, wafer, lot [0082], standard deviation, sigma’s, overlay distribution [0094], diagnostic metric distribution on the wafer map [0108], algorithms, overlay error [0116, 0118 -0123])
Seligson is in the same art of process control using overlay target data as Adel.
Therefore, it would have been obvious to one of ordinary skill in the art at the time when invention is filed before the effective filing date of the application to modify the teachings of Adel in view of Seligson to generate a quality metric for each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers based on overlay metrology measurement signals associated with the plurality of metrology targets by multiple overlay algorithms to the overlay metrology measurement signals for the particular metrology target to generate an overlay estimate distribution with a rationale to achieve an accurate overlay measurements for an overlay metrology tool (See Adel – accurately [0005], optical characteristics, accurately describe the induced phase error [0009], overlay metrology, accurate possible feedback [0018]).
However, the combined prior art is silent regarding use of a statistical property including at least one of a span or spread function of the overlay estimate distribution for generating overlay estimate distribution and the quality metric.
Adel-NPL discloses applying multiple overlay algorithms to the overlay metrology measurement signals for the particular metrology target (design of optimal pattern, algorithm [pg. 170 left col par 1 from the bottom – pg. 171 right col par 1 from the bottom],multiresolution algorithms for faster pattern registration and position disambiguation ‘anti-aliasing’ [pg. 173 left col par. 1], optimized measurement algorithm [pg. 174 left col par 1], distribution algorithm [pg. 177 left col par 3-4]) and use of a statistical property including at least one of a span or spread function of the overlay estimate distribution for overlay estimate distribution and the quality metric (point spread function, derive the distribution of the pattern location estimates over all measurement, statistical analysis [pg. 168 right col par. 1], spread function [pg. 169 left col par 1, par 2 from the bottom], estimation error, observed signal, point spread function ‘PSF’ [pg. 169 par 304], distribution algorithm [pg. 177 left col par 4], metric of the quality [pg. 167 left col par 5]).
Adel-NPL is also in the same overlay metrology art as the combined prior art.
Therefore, it would have been obvious to one of ordinary skill in the art at the time when invention is filed before the effective filing date of the application to modify the teachings of the combined prior art in view of Adel-NPL to apply multiple overlay algorithms to the overlay metrology measurement signals for the particular metrology target to generate an overlay estimate distribution and generating the quality metric based on a statistical property including at least one of a span or spread function of the overlay estimate distribution with a rationale to achieve an accurate overlay measurements for an overlay metrology tool.
Adel further discloses
determining a modified overlay function providing a plurality of modified overlay values for the plurality of metrology targets utilizing the acquired overlay metrology result and the associated quality metric for each metrology target, (receiving calibration data ‘block 30’ and the overlay measurements ‘block 26’, making a prediction of the overlay error at any point in the wafer and field, and more particularly the overlay error of a device structure at its position in the field [0072, Fig. 3 28])
wherein the modified overlay function is a function of at least one material parameter factor; (overlay processing, specific materials [0068, Fig. 3 20], different stepper settings ‘e.g., illumination, focus [0087], illumination settings, aperture, focus [0088], showing examples of material factors – see specification material parameter factor, wavelength, focus position, illumination angle [0073, Eq 6], overlay metrology tool, Pattern Placement Error of perturbing, wavelength, illumination source [0139], scanner parameters [0140])
generating a process tool correctable function for the one or material factors (lithography tool overlay control ‘e.g., correctables’ or product lot dispositioning ‘e.g., rework’ [0018], calculate the correctables … with their corresponding design rules [0077, Fig. 3 34], overlay processing, specific materials [0068, Fig. 3 20], different stepper settings ‘e.g., illumination, focus [0087], illumination settings, aperture, focus [0088], showing examples of material factors, optimal correctables [0078], correctables, used for lot disposition metrics [0079]) and recites residual pattern placement error deviations (minimum contrast requirements for the target as measured on the overlay tool and exact replication of the device PPE, A Pattern Placement Error, residual PPE deviations [0107, 0138]), but is not explicit regarding
generating a process tool correctable function and a set of residuals corresponding with the process tool correctable function.
Sullivan explicitly discloses modeling overlay correctables are corresponding to a set of residuals (modeling, correct the systematic sources of overlay error, overlay error, residual [pg. 503 left col par. 1 – right col par. 1, eq, 1-2]) and also discloses the modified overlay value is a function of at least one material parameter factor (measurement accuracy, Tool Induced Shift ‘TIS’ [pg. 504 left col par. 2], TIS is a very complex function of … optical configuration, substrate material [pg. 505 right col par. 1]).
Therefore, it would have been obvious to one of ordinary skill in the art at the time when invention is filed before the effective filing date of the application to modify the teachings of the combined prior art in view of Sullivan to generate a process tool correctable function and a set of residuals corresponding with the process tool correctable function for each of multiple values of the one or more material parameter factors to achieve an accurate overlay measurements for an overlay metrology tool.
Sullivan further discloses
determining values of the one or more material parameter factors providing minimized values of the set of residuals; (quantify and assign the contribution of the measurement tool's error component to the measured value and to minimize its impact via a hardware modification ‘e.g. optical alignment / columniation’ or software calibration [pg. 504 left col par. 2]),
and determining a set of process correctables based on the values of the one or more material parameter factors providing minimized values of the set of residuals (define … generic overlay target design rules, minimize z distance between levels, CMP process, minimize topography, Fundamental system design for W CMP overlay metrology, short wavelength illumination ‘for improved resolution’ and a choice of bandwidth which minimizes both chromatic aberrations [pg. 507 left col par. 1 – pg. 509 left col par. 2]), but is not explicit regarding
controlling one or more process tools utilizing at least one of feedback or feedforward control based on the set of process correctables.
Seligson further discloses fitting the overlay function considering different factors (other factors [0004], factors, ROI [0050]) and controlling one or more process tools utilizing at least one of feedback or feedforward control based on the set of process correctables (process control, stepper, cell controller [0090], process tools [0110], advanced process control [0150])
Therefore, it would have been obvious to one of ordinary skill in the art at the time when invention is filed before the effective filing date of the application to modify the teachings of the combined prior art to determine a set of process correctables based on the values of the one or more material parameter factors and controlling one or more process tools utilizing at least one of feedback or feedforward control based on the set of process correctables with a rationale to achieve an accurate overlay measurements for an overlay metrology tool.
As per claim 3, Adel, Seligson, Adel-NPL and Sullivan disclose claim 1 set forth above.
Adel further discloses wherein the overlay measurement signals are associated with overlay measurements performed on each of the metrology targets of the plurality of metrology targets. (overlay measurements are performed via targets that are printed together with layers of the wafer [0005], overlay metrology, many overlay targets [0008], characterization having plurality of overlay targets, including … measuring the overlay error of the overlay targets [0021]).
As per claim 7, Adel, Seligson, Adel-NPL and Sullivan disclose claim 1 set forth above.
Adel discloses the overlay measurement result is a function of at least one of a wavelength of illumination, a focus position, a direction of illumination, a polarization configuration, or a filter configuration (overlay measurement, analysis routine that calculates correctables and other statistics, [0007], estimate impact … on overlay … pattern placement error, require detailed knowledge of … process parameters … illumination configuration, wavelength [0010], predict overlay error, parameters … lens aberrations, focus [0057], overlay measurement may be performed using a variety of methods and metrology tools … may be performed using imaging, scanning, scatterometry [0067], focusing step, the tool is moved along the z axis until the surface of the wafer is in focus [0156, Fig. 18], equivalent to focus position).
Sullivan also discloses observations made on optics TIS, i.e. modified overlay result, is a function of … optical configuration and substrate material (observation … optics TIS … function of … optical configuration, and substrate material [pg. 505 right col par. 1]).
Therefore, it would have been obvious to one of ordinary skill in the art at the time when invention is filed before the effective filing date of the application to modify the teachings of the combined prior art to configure the modified overlay result to be a function of at least one of a wavelength of illumination, a focus position, a direction of illumination, a polarization configuration, or a filter configuration to achieve an accurate overlay measurements for an overlay metrology tool.
Claim 4 is rejected under 35 U.S.C. 103 as being unpatentable over Adel, Seligson, Adel-NPL and Sullivan in view of Izikson (US 20110202298 A1).
As per claim 4, Adel, Seligson, Adel-NPL and Sullivan disclose claim 1 set forth above.
The set forth combined prior art is silent regarding transmitting the set of process tool correctables to the one or more process tools.
Izikson discloses transmitting the set of process tool correctables to one or more process tools (transmit instructions to one or more process tools, the transmitted instructions may contain information indicative of overlay, focus, and dose correctables [0031], correctable table described above may then be transmitted to one or more measurement tools or process tools to provide corrections to these systems [0081]).
Therefore, it would have been obvious to one of ordinary skill in the art at the time when invention is filed before the effective filing date of the application to modify the teachings of the combined prior art in view of Izikson to transmit the set of process tool correctables associated with the at least substantially minimized set of residuals to one or more process tools to achieve an accurate overlay measurements for an overlay metrology tool.
Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Adel, Seligson, Adel-NPL and Sullivan in view of Cresswell (US 5617340 A).
As per claim 5, Adel, Sullivan and Eichelberger disclose claim 1 set forth above
Sullivan further discloses regarding a tool induced shift ‘TIS’ (variations in TIS as shown in Figure 4, both within and across wafers, are due to an interaction of the tool asymmetry ‘TIS’ and the process asymmetry ‘WIS’ [pg. 506 left col line 11-13], the measurement inaccuracy … can be greater, inaccuracy must be addressed through measurement target design optimization and measurement algorithm, [pg. 506 left col line 9-1 from the bottom], measurement algorithm [pg. 506 right col]), but is silent regarding performing a tool induced shift (TIS) correction process to at least some of the acquired plurality of overlay metrology measurement signals.
Cresswell discloses performing a tool induced shift (TIS) correction process to at least some of the acquired plurality of overlay metrology measurement signals (subsequent measurements could be corrected for such tool-induced shift [col 11 line 35-49])
Therefore, it would have been obvious to one of ordinary skill in the art at the time when invention is filed before the effective filing date of the application to modify the teachings of the combined prior art in view of Cresswell to perform a tool induced shift (TIS) correction process to at least some of the acquired plurality of overlay metrology measurement signals to achieve an accurate overlay measurements for an overlay metrology tool.
Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Adel, Seligson, Adel-NPL and Sullivan in view of Ferrera (Ferrera, Juan Ferrera Uranga. "Nanometer-scale placement in electron-beam lithography." PhD diss., Massachusetts Institute of Technology, 2000).
As per claim 6, Adel, Seligson, Adel-NPL and Sullivan disclose claim 1 set forth above.
The set forth combined prior art is silent regarding the modified overlay function is a linear function of at least one material parameter factor.
Ferrera discloses the modified overlay value is obtained using a linear relationship of at least one material parameter factor (the relationship between the detector signal and beam displacement is approximately linear [pg. 184 par. 1]).
Therefore, it would have been obvious to one of ordinary skill in the art at the time when invention is filed before the effective filing date of the application to modify the teachings of the combined prior art in view of Ferrera to set the modified overlay function as a linear function of at least one material parameter factor to achieve an accurate overlay measurements for an overlay metrology tool.
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Adel in view of Seligson, Adel-NPL and Cohen (US 20120029856 A1).
As per claim 8, Adel discloses
A computer-implemented method for identifying a variation in process tool correctables, (overlay method, correcting the overlay error … based on the calibration data [abs], variations of the process [0058], process are modeled via computer programs [0061], correctables, incorporate the subtleties of the stepper and the device structure [0078], calculating correctables … lot dispersion metrics … refer to … quality of the lithographic pattern [0079]) comprising:
generating an overlay metrology result for each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers; (measure … product wafer [Fig. 3 26], measure patterns on wafer [Fig. 4 46])
generating a quality metric associated with each acquired overlay metrology result; (quantitative metrics for the quality, exposure tool illumination configuration, wavelength, numerical aperture and the geometry of the pattern, overlay metrology [0010], the overlay data contained in the calibration data, relationship … between process robust and device representing targets, a signature [0072, Fig. 3 28 30], metrics [0079], overlay metrology, metrics [0162])
However, Adel is silent regarding a quality metric for each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers based on overlay metrology measurement signals associated with the plurality of metrology targets, wherein the quality metric for a particular metrology target of the plurality of metrology targets is generated by applying multiple overlay algorithms to the overlay metrology measurement signals for the particular metrology target to generate an overlay estimate distribution and generating the quality metric based on a statistical property of the overlay estimate distribution.
Seligson discloses generating a quality metric for each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers based on overlay metrology measurement signals associated with the plurality of metrology targets (analyzing the quality of overlay targets [abs, 0005], quantitative metric on a quality of the overlay error [0008, 0056, claims 5 and 13], quality or confidence level [0058], wafer, lot [0082], overlay distribution [0094], diagnostic metric distribution on the wafer map [0108]),
wherein the quality metric for a particular metrology target of the plurality of metrology targets is generated by applying multiple overlay algorithms to the overlay metrology measurement signals for the particular metrology target to generate an overlay estimate distribution and generating the quality metric based on a statistical property of the overlay estimate distribution. (techniques or algorithms for measuring … a target [0046], measurement algorithm [0048], characterizing noise data … algorithms [0049, claim 4], target diagnostic, quality or confidence level, targets, algorithms [0058], standard deviation, sigma, distribution [0076, 0078], algorithms, wafer, lot [0082], three sigma, overlay distribution [0094], diagnostic metric distribution on the wafer map [0108], algorithms, overlay error [0116, 0118 -0123])
Seligson is in the same art of process control using overlay target data as Adel.
Therefore, it would have been obvious to one of ordinary skill in the art at the time when invention is filed before the effective filing date of the application to modify the teachings of Adel in view of Seligson to generate a quality metric for each metrology target of a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers based on overlay metrology measurement signals associated with the plurality of metrology targets by multiple overlay algorithms to the overlay metrology measurement signals for the particular metrology target to generate an overlay estimate distribution with a rationale to achieve an accurate overlay measurements for an overlay metrology tool.
However, the combined prior art is silent regarding use of a statistical property including at least one of a span or spread function of the overlay estimate distribution for generating overlay estimate distribution and the quality metric.
Adel-NPL discloses applying multiple overlay algorithms to the overlay metrology measurement signals for the particular metrology target (design of optimal pattern, algorithm [pg. 170 left col par 1 from the bottom – pg. 171 right col par 1 from the bottom],multiresolution algorithms for faster pattern registration and position disambiguation ‘anti-aliasing’ [pg. 173 left col par. 1], optimized measurement algorithm [pg. 174 left col par 1], distribution algorithm [pg. 177 left col par 3-4]) and use of a statistical property including at least one of a span or spread function of the overlay estimate distribution for overlay estimate distribution and the quality metric (point spread function, derive the distribution of the pattern location estimates over all measurement, statistical analysis [pg. 168 right col par. 1], spread function [pg. 169 left col par 1, par 2 from the bottom], estimation error, observed signal, point spread function ‘PSF’ [pg. 169 par 304], distribution algorithm [pg. 177 left col par 4], metric of the quality [pg. 167 left col par 5]).
Adel-NPL is also in the same overlay metrology art as the combined prior art.
Therefore, it would have been obvious to one of ordinary skill in the art at the time when invention is filed before the effective filing date of the application to modify the teachings of the combined prior art in view of Adel-NPL to apply multiple overlay algorithms to the overlay metrology measurement signals for the particular metrology target to generate an overlay estimate distribution and generating the quality metric based on a statistical property including at least one of a span or spread function of the overlay estimate distribution with a rationale to achieve an accurate overlay measurements for an overlay metrology tool.
Adel further discloses
determining a plurality of modified overlay values for the plurality of metrology targets utilizing the acquired overlay metrology result for each metrology target and a quality function, (receiving calibration data ‘block 30’ and the overlay measurements ‘block 26’, making a prediction of the overlay error at any point in the wafer and field, and more particularly the overlay error of a device structure at its position in the field [0072, Fig. 3 28])
the quality function being a function of the acquired quality metric of each metrology target; (overlay targets, overlay marks [0011], metrics … used to determine the overlay mark fidelity, tightness of the distribution of the overlay results [0162], showing quality as a function of metrics, perform acquisition in overlay mark [0156, Fig. 344])
However, Adel is silent regarding determining a set of process tool correctables for each of a plurality of randomly selected samplings of the acquired overlay metrology results, wherein each of the random samplings is of the same size.
Cohen discloses determining a set of process tool correctables for each of a plurality of randomly selected samplings of the acquired overlay metrology results, wherein each of the random samplings is of the same size (random sub-samples, each of the subsampling is of the same size [0064, claims 3, 13 and 19], a set of calculations of correctables with 50 random sub-samplings [0065, Fig. 5]).
Therefore, it would have been obvious to one of ordinary skill in the art at the time when invention is filed before the effective filing date of the application to modify the teachings of Adel in view of Cohen to generate a plurality of sets of process tool correctables by determining a set of process tool correctables for each of a plurality of randomly selected samplings of the acquired overlay metrology results and the associated quality metrics of the plurality of metrology targets utilizing the plurality of modified overlay values, wherein each of the random samplings is of the same size to achieve an accurate overlay measurements for an overlay metrology tool.
Adel further discloses and identifying a variation in the plurality of sets of process tool correctables. (correctables, incorporate the subtleties of the stepper and the device structure [0078], calculating correctables … lot dispersion metrics … refer to … quality of the lithographic pattern [0079]).
Seligson further discloses fitting the overlay function considering different factors (other factors [0004], factors, ROI [0050]) and controlling one or more process tools utilizing at least one of feedback or feedforward control based on the set of process correctables (process control, stepper, cell controller [0090], process tools [0110], advanced process control [0150])
Therefore, it would have been obvious to one of ordinary skill in the art at the time when invention is filed before the effective filing date of the application to modify the teachings of the combined prior art to determine a set of process correctables based on the values of the one or more material parameter factors and controlling one or more process tools utilizing at least one of feedback or feedforward control based on the set of process correctables with a rationale to achieve an accurate overlay measurements for an overlay metrology tool.
Notes with regard to Prior Art
The prior arts made of record and not relied upon are considered pertinent to applicant's disclosure.
Pellegrini (Pellegrini, Joseph C., and et al. "Supersparse overlay sampling plans: an evaluation of methods and algorithms for optimizing overlay quality control and metrology tool throughput." In Metrology, Inspection, and Process Control for Microlithography XIII, vol. 3677, pp. 72-82. SPIE, 1999) discloses a span or spread of the overlay estimation distribution (RMS value of distribution … of the overlay sampling [pg. 79 par. 1], distribution, S.D, size [Fig. 13 & 14]).
Levinson (Levinson, Harry J., and et al. "Minimization of total overlay errors on product wafers using an advanced optimization scheme." In Optical Microlithography X, vol. 3051, pp. 362-373. SPIE, 1997) discloses the matching of wafer steppers is accomplished typically by patterning two successive layers, using different steppers of interest for each layer, and measuring the overlay at many points in the exposure field. Matching is considered to be optimized when some metric, such the sum-of-squares of overlay errors, is minimized over all measured points within the field. This is to be contrasted to the situation which arises during the in-line measurement of overlay errors in production, where a far more limited sampling of points [abs].
Zavec (Zavecz, Terrence E., and Rene M. Blanquies. "Predictive process control for sub-0.2-um lithography." In Metrology, Inspection, and Process Control for Microlithography XIV, vol. 3998, pp. 416-427. SPIE, 2000) also discloses “a statistical property including at least one of a span or spread function of the overlay estimate distribution” (overlay distribution … wafer and lot [abs], Data provides valuable insights into not only tool stability but also process-step characteristic errors that contribute to the overlay spectrum of distortions, algorithm [pg. 416 par. 1], statistic, distribution, spreading, spreads [pg. 422 par 3 from the bottom]).
Contact Information
Any inquiry concerning this communication or earlier communications from the examiner should be directed to DOUGLAS KAY whose telephone number is (408)918-7569. The examiner can normally be reached on M, Th & F 8-5, T 2-7, and W 8-1.
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/DOUGLAS KAY/Primary Examiner, Art Unit 2857