DETAILED ACTION
Notice of Pre-AIA or AIA Status
1. The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Election/Restrictions
2. Applicant's election with traverse of Group I in the reply filed on 25 August 2026 is acknowledged. The traversal is on the ground(s) that
(a) the special technical feature shared among all of the claims are not taught by the prior art of records (pg. 2-5)
(b) the claims do not require a materially different search (pg. 6)
(c) the Internation Searching Authority raised no lack-of-unity objection and found claims to be novel and to involve an inventive step (pg. 2)
(d) Species I-A, I-B, I-C are alternative refinements of a single acquisition-time model pg. 5-6)
(e) Claim 16 recites the same technical features that claim 1 recites (pg. 5)
This is not found persuasive because the shared technical feature is obvious over newly found references, as detailed in the rejection of claim 1 below. The Office makes its own determination of unity of invention based on the prior art of record, and the findings of the International Searching Authority are not binding on the Office. Because the technical feature common to claims 1 and 16 is not special, sharing of the feature does not establish unity between Groups I and II. The technical feature common to Species I-A, I-B, and I-C is the feature of generic claims 1 and 10, which is not special, and that the specification describes these parameters as inputs to one model does not make them the same or corresponding special technical features. Lack of unity is determined upon whether the claimed inventions share a special technical feature, not on search burden. Even if search burden were considered, the groups require different search queries. Group I requires search focused on determining SEM imaging conditions for overlay measurement from backscattered-electron contrast. Group II requires search focused on a yield model that computes the BSE yields from the stack parameters and the beam parameters and BSE yields pre-determined by a heuristic or machine learning model.
Claims 5, 7, 14 and 16-20 are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected Group II, Species I-A and I-C, there being no allowable generic or linking claim.
The requirement for election between species II-A and II-B is hereby withdrawn as to Group I. Claims 2-4 and 11-13 reciting species II-A and II-B are examined.
The requirement is still deemed proper and is therefore made FINAL.
Claim Rejections - 35 USC § 101
3. 35 U.S.C. 101 reads as follows:
Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefore, subject to the conditions and requirements of this title.
4. Claims 1-4, 6, 8-13, and 15 are rejected under 35 U.S.C. 101 because the claimed invention is directed to the abstract idea of a mathematical concept without significantly more. The independent claim(s) (claims 1 and 10) recite(s) a mathematical concept as two steps: 1) determining an acquisition time for the overlay measurement of a wafer stack based on a plurality of characteristics of the wafer stack and a plurality of backscattered electron (BSE) yields detected at a plurality of features on the wafer stack; 2) determining the one or more parameters including a landing energy of the e-beam based on optimization of the acquisition time for the overlay measurement; etc.
In the instant case, the two determining steps of the independent claims are mathematical calculations. For instance: step 1 takes numerical values (characteristics of the wafer and numerical BSE yields) and computes a numerical acquisition time from them. Step 2 determines a numerical landing energy based on optimization the acquisition time. Optimization or finding the value of a variable that minimizes or maximizes a function is a mathematical operation. The claims therefore recite mathematical relationships in words and calculations operating on data to produce a result.
5. Furthermore, the dependent claims do not recite any features that would change the abstract idea into something more. Dependent claims 2-4, 11-13 add further details to the characteristics of the wafer stack used in the calculation: a density or atomic number of the materials, the geometries or dimensions of the features, and a pitch of buried line features. These details merely specify additional variables in the calculation. They do not alter the fact that the underlying abstract idea is a mathematical concept. Claims 6 and 15 add that the acquisition time is further based on hardware parameters related to a detector efficiency, which is simply one more variable in the calculation. Claim 8 adds determining a beam current based on the optimization of the acquisition time, which is one more output of the same optimization. Claim 9 adds fitting signal measurements using at least squares regression analysis and optimizing the acquisition time based on a standard deviation, which are not significantly more than the abstract idea itself since they merely add further mathematics to the determination.
6. The claims recite various features, but none of them, taken alone or in an ordered combination, is significantly more than just the above noted mental process. Simply put, the claims do not require that anything other than the calculation of an acquisition time and a landing energy occur. To the extent that the process must occur in a computer (the controller including circuitry of claim 1; the non-transitory computer readable medium and at least one processor of claim 10), this is a requirement that a generic computer perform generic computer functions, e.g., running an algorithm. Such a requirement to apply an abstract idea using a generic computer does not render an abstract idea patent eligible. Alice Corp. Pty. Ltd. v. CLS Bank Int'l, 573 U.S. 208, 223, 110 USPQ2d 1976, 1983 (2014).
7. Finally, this judicial exception is not integrated into a practical application because the calculated acquisition time and landing energy are not applied to anything external to the abstract idea. The claims do not require that the e-beam be operated at the determined landing energy or for the determined acquisition time, that the wafer stack be imaged, or than an overlay measurement be performed. The claims end with the parameters having been determined. The recitation that the parameters are “used by an e-beam for an overlay measurement” merely identifies a field of use (MPEP 2106.05(h)).
Any improvement in measurement throughput described in the specification ([0070]-[0071]) would result from using the calculated parameters to operate the e-beam, which the claims do not recite. The judicial exception alone cannot provide the improvement (MPEP 2106.05(a)).
Claim Rejections - 35 USC § 103
8. 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 (i.e., changing from AIA to pre-AIA ) 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.
9. 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.
10. Claims 1-4 and 10-13 are rejected under 35 U.S.C 103 as being unpatentable over Sugie (WO 2021038649) in view of Mukhtar, M., & Thiel, B. (2018). Backscattered electron simulations to evaluate sensitivity against electron dosage of buried semiconductor features. In Proceedings Volume 10585, Metrology, Inspection, and Process Control for Microlithography XXXII (p. 105852L). International Society for Optics and Photonics (SPIE). SPIE Digital Library. https://doi.org/10.1117/12.2314665 [hereinafter Mukhtar].
11. Regarding claim 1:
Sugie teaches a system for determining one or more parameters used by an e-beam for an overlay measurement (pg. 2 fig. 1 teaches the overlay measurement system 100 including an imaging tool 120, a scanning electron microscope that irradiates a sample with a primary electron beam), the system comprising:
a controller including circuitry configured to cause the system (pg. 2 fig. 1 teaches computer subsystem 121. Pg. 3 teaches that the computer subsystem 121 includes an arithmetic processing unit 118) to perform:
determining an acquisition time for the overlay measurement of a wafer stack (pg. 2 teaches that the sample is a wafer having an upper layer pattern and a lower layer pattern. Pg. 4 teaches that the lower layer pattern is a line pattern formed under the film to be etched, (organic film, insulating film, etc.), i.e., a wafer stack. Pg. 5 teaches that the number of frames may be automatically determined by using the following frame number determination process. Pg. 4 teaches that each frame is one scan, and a high frame image reduces the throughput of the overlay measurement system due to the large number of scans. The integrated frame number therefore sets the acquisition time) based on a plurality of backscattered electron (BSE) yields detected at a plurality of features on the wafer stack (pg. 5 fig. 5 teaches increasing the number of frames to be added for acquiring the reflected electron image by one frame (S21), the evaluation value of the SUMLINE profile obtained from the acquired reflected electron image is confirmed (S22, S23). The evaluation value is the amount of change in brightness of the SUMLINE profile. Fig. 5 steps S21-S24 teach increasing the number of frames by one frame (S21), confirming the evaluation value of the SUMLINE profiled obtained from the acquired reflected electron image (S22, S23), and adopting the number of frames when the evaluation value becomes equal to or higher than the threshold value (S24). Pg. 4 teaches that brightness change is the contrast that appears between the line 211 and the space pattern 212 in the reflected electron image 210. The BSE signals detected by backscattered electron detector 109 at lines 211 and spaces 212 are BSE yields detected at a plurality of features. The acquisition time is therefore determined from BSE signals detected at a plurality of features).
Sugie does not specifically teach that the acquisition time is determined based on a plurality of characteristics of the wafer stack; and determining the one or more parameters including a landing energy of the e-beam based on optimization of the acquisition time for the overlay measurement.
Mukhtar teaches determining an acquisition time for an overlay measurement of a wafer stack based on a plurality of characteristics of the wafer stack and a plurality of BSE yields at a plurality of features on the wafer stack (Mukhtar’s sample is a stack in which metal lines are covered by an oxide layer. Pg. 3 section 3.1 teaches the Au and Cu gratings buried under SiO2. Pg. 1 introduction teaches 10 nm line/space gratings of graduated increase in depth of burial. Pg. 1 abstract teaches that in order to measure overlay of buried features, HV-SEM is needed. The buried lines and the oxide are the plurality of features. Then, pg. 3 defines that the BSE yield is given by the ratio of electrons arriving at the detector to the number incident at the sample. Mukhtar uses two yields: the yield of the oxide [pg. 4 teaches ηref is the backscatter yield of the background material], and the yield difference between the buried line and the oxide [pg. 4 teaches C is the contrast between the material in question and the background]. These two yields are BSE yields at a plurality of features. The yields depend on what the stack is made of and how it is built [pg. 3 teaches that contrast between Cu and SiO2 is much better]. Mukhtar also teaches that the sensitivity changes with how deep the lines are buried [fig. 6, pg. 4-5]. Material, atomic number and burial depth are characteristics of the wafer stack. Pg. 4 teaches measuring sensitivity, i.e., how clearly the buried line stands out above noise (ΔS/N), as [C*ηref *((IB*τ)/e)] ÷ [ηref*((IB*τ)/e)]^0.5, where I_B is the beam current, τ is the dwell time, i.e., how long the beam stays on each pixel [pg.4]. Rearranged, the dwell time is set by the two BSE yields, C and ηref, which in turns are set by stack characteristics. Figs. 7-9 plots the relationship: sensitivity of the buried feature vs. dwell time. Mukhtar therefore determines an acquisition time based on the stack characteristics and the BSE yields at the features);
and determining the one or more parameters including a landing energy of the e-beam based on optimization of the acquisition time for the overlay measurement (under broadest reasonable interpretation, the limitation reads on choosing the landing energy that reaches the required measurement precision in the least acquisition time (as supported by [0054] of the instant specification). Mukhtar pg. 1 calculates the sensitivity measurements of buried features versus electron dosage for an array of electron beam voltages. Figs. 7-9 then plot sensitivity against dwell time separately at 5 keV and at 30keV. As the curves of figs. 7-9 show, at every dwell time, one landing energy gives higher sensitivity than the other. Then that energy reaches the required sensitivity sooner with a shorter acquisition time. Mukhtar identifies which energy is better for which stack [pg. 7 teaches that for the Au gratings, the sensitivity results are better under 5keV landing energy until the depth of burial increases to 30nm where the 30keV landing energy produces slightly better results. Also see figs. 9-10, 30nm plot lines for Au BSE at 30keV and 5keV respectively at 1000 ns dwell time]. Choosing between 5keV and 30keV by which one reaches the required sensitivity in less dwell time is determining the landing energy based on optimization of the acquisition time).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to have modified Sugie’s controller in view of Mukhtar to include determining the integrated frame number (acquisition time) from the characteristics of the wafer stack and from BSE signals of line features 211 and space features 212, expressed as BSE yields according to Mukhtar’s sensitivity relation; and set the acceleration voltage 1002, taught in Sugie pg. 7, to the landing energy that reaches the required sensitivity with the shortest acquisition time. One of ordinary skill in the art would be motivated to make such modification to calculate the sensitivity measurements of buried features versus electron dosage for any array of electron beam voltages (Mukhtar pg. 1) and to access the sensitivity of buried features versus electron dosage (Mukhtar pg. 2).
12. Regarding claim 2:
The modified invention above teaches the system of claim 1. Sugie does not specifically teach wherein the plurality of characteristics of the wafer stack comprise a density or an atomic number of materials in the wafer stack.
Mukhtar teaches wherein the plurality of characteristics of the wafer stack comprise a density or an atomic number of materials in the wafer stack (pg. 3 teaches that the contrast between Si and SiO2 under SiO2 is weak, while contrast between Cu and SiO2 is much better (Z and density are considerably different) so that individual Cu lines can be resolved under up to 100nm of SiO2).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to have modified Sugie in view of Mukhtar to include that the plurality of characteristics of the wafer stack comprise a density or an atomic number of materials in the wafer stack. One of ordinary skill in the art would be motivated to make such modification because the atomic number and density of the buried line and the surrounding material determine how readily the buried line can be resolved, ensuring that the acquisition time is sufficient for the materials of the particular stack being measured (Mukhtar pg. 3-4).
13. Regarding claim 3:
The modified invention above teaches the system of claim 1. Sugie does not specifically teach wherein the plurality of characteristics of the wafer stack comprise geometries or dimensions of the plurality of features on the wafer stack.
Mukhtar teaches wherein the plurality of characteristics of the wafer stack comprise geometries or dimensions of the plurality of features on the wafer stack (pg. 3 teaches that buried lines have defined dimensions where the gratings are 40nm in height, 10nm in width, and a pitch of 30nm. Figs. 9-10 shows separate sensitivity-vs-dwell-time curve for each burial depth, and the needed dwell time changes sharply with depth. For Au at 5keV, a sensitivity of about 2 is reached in about 50ns when the lines are buried 10nm deep, but takes about 1000 ns when they are buried 40nm deep (fig. 9). The dwell time is therefore determined based on the dimensions of the buried line features).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to have modified Sugie in view of Mukhtar to include that wherein the plurality of characteristics of the wafer stack comprise geometries or dimensions of the plurality of features on the wafer stack. One of ordinary skill in the art would be motivated to make such modification to ensure that the acquisition time is sufficient for the particular buried pattern being measured (Mukhtar pg. 7-8).
14. Regarding claim 4:
The modified invention above teaches the system of claim 3. Sugie further teaches that wherein the plurality of features include a set of buried line features (pg. 4 teaches that the lower layer pattern is a line pattern formed under the film to be etched (organic film, insulating film, etc)). Sugie does not specifically teach that wherein the dimensions of the buried line features include a pitch.
Mukhtar teaches that wherein the dimensions of the buried line features include a pitch (pg. 3 teaches that the gratings are 40nm in height, 10nm in width, and a pitch of 30nm. Pg. 1 and figs. 6-10 teaches computing the sensitivity-vs-dwell-time curves for 10nm line/space gratings. A line/space designation specifies the width of each line and the spacing between adjacent lines, which together define the pitch. The instant specification defines pitch the same way ([0063] instant specification teaches that a pitch corresponds to a spacing between adjacent lines) Under broadest reasonable interpretation, the claim requires only that the dimension on which the acquisition time is based includes a pitch).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to have modified Sugie in view of Mukhtar to include that wherein the dimensions of the buried line features include a pitch. One of ordinary skill in the art would be motivated to make such modification so that the sensitivity and acquisition time is computed for a grating matching the buried line pattern being measured (Mukhtar pg. 1, 3-4).
15. Regarding claim 10:
Sugie teaches A non-transitory computer readable medium that stores a set of instructions that is executable by at least one processor of a system (pg. 2 fig. 1 teaches computer subsystem 121. Pg. 3 teaches that the computer subsystem 121 includes a storage device 124 and an arithmetic processing unit 118. Pg. 3 teaches that the arithmetic processing unit 118 includes a processor) to cause the system to perform a method of determining one or more parameters used by an e-beam for an overlay measurement (pg. 2 fig. 1 teaches the overlay measurement system 100 including an imaging tool 120, a scanning electron microscope that irradiates a sample with a primary electron beam), the method comprising:
determining an acquisition time for the overlay measurement of a wafer stack (pg. 2 teaches that the sample is a wafer having an upper layer pattern and a lower layer pattern. Pg. 4 teaches that the lower layer pattern is a line pattern formed under the film to be etched, (organic film, insulating film, etc.), i.e., a wafer stack. Pg. 5 teaches that the number of frames may be automatically determined by using the following frame number determination process. Pg. 4 teaches that each frame is one scan, and a high frame image reduces the throughput of the overlay measurement system due to the large number of scans. The integrated frame number therefore sets the acquisition time) based on a plurality of backscattered electron (BSE) yields detected at a plurality of features on the wafer stack (pg. 5 fig. 5 teaches increasing the number of frames to be added for acquiring the reflected electron image by one frame (S21), the evaluation value of the SUMLINE profile obtained from the acquired reflected electron image is confirmed (S22, S23). The evaluation value is the amount of change in brightness of the SUMLINE profile. Fig. 5 steps S21-S24 teach increasing the number of frames by one frame (S21), confirming the evaluation value of the SUMLINE profiled obtained from the acquired reflected electron image (S22, S23), and adopting the number of frames when the evaluation value becomes equal to or higher than the threshold value (S24). Pg. 4 teaches that brightness change is the contrast that appears between the line 211 and the space pattern 212 in the reflected electron image 210. The BSE signals detected by backscattered electron detector 109 at lines 211 and spaces 212 are BSE yields detected at a plurality of features. The acquisition time is therefore determined from BSE signals detected at a plurality of features).
Sugie does not specifically teach that the acquisition time is determined based on a plurality of characteristics of the wafer stack; and determining the one or more parameters including a landing energy of the e-beam based on optimization of the acquisition time for the overlay measurement.
Mukhtar teaches determining an acquisition time for an overlay measurement of a wafer stack based on a plurality of characteristics of the wafer stack and a plurality of BSE yields at a plurality of features on the wafer stack (Mukhtar’s sample is a stack in which metal lines are covered by an oxide layer. Pg. 3 section 3.1 teaches the Au and Cu gratings buried under SiO2. Pg. 1 introduction teaches 10 nm line/space gratings of graduated increase in depth of burial. Pg. 1 abstract teaches that in order to measure overlay of buried features, HV-SEM is needed. The buried lines and the oxide are the plurality of features. Then, pg. 3 defines that the BSE yield is given by the ratio of electrons arriving at the detector to the number incident at the sample. Mukhtar uses two yields: the yield of the oxide [pg. 4 teaches ηref is the backscatter yield of the background material], and the yield difference between the buried line and the oxide [pg. 4 teaches C is the contrast between the material in question and the background]. These two yields are BSE yields at a plurality of features. The yields depend on what the stack is made of and how it is built [pg. 3 teaches that contrast between Cu and SiO2 is much better]. Mukhtar also teaches that the sensitivity changes with how deep the lines are buried [fig. 6, pg. 4-5]. Material, atomic number and burial depth are characteristics of the wafer stack. Pg. 4 teaches measuring sensitivity, i.e., how clearly the buried line stands out above noise (ΔS/N), as [C*ηref *((IB*τ)/e)] ÷ [ηref*((IB*τ)/e)]^0.5, where I_B is the beam current, τ is the dwell time, i.e., how long the beam stays on each pixel [pg.4]. Rearranged, the dwell time is set by the two BSE yields, C and ηref, which in turns are set by stack characteristics. Figs. 7-9 plots the relationship: sensitivity of the buried feature vs. dwell time. Mukhtar therefore determines an acquisition time based on the stack characteristics and the BSE yields at the features);
and determining the one or more parameters including a landing energy of the e-beam based on optimization of the acquisition time for the overlay measurement (under broadest reasonable interpretation, the limitation reads on choosing the landing energy that reaches the required measurement precision in the least acquisition time (as supported by [0054] of the instant specification). Mukhtar pg. 1 calculates the sensitivity measurements of buried features versus electron dosage for an array of electron beam voltages. Figs. 7-9 then plot sensitivity against dwell time separately at 5 keV and at 30keV. As the curves of figs. 7-9 show, at every dwell time, one landing energy gives higher sensitivity than the other. Then that energy reaches the required sensitivity sooner with a shorter acquisition time. Mukhtar identifies which energy is better for which stack [pg. 7 teaches that for the Au gratings, the sensitivity results are better under 5keV landing energy until the depth of burial increases to 30nm where the 30keV landing energy produces slightly better results. Also see figs. 9-10, 30nm plot lines for Au BSE at 30keV and 5keV respectively at 1000 ns dwell time]. Choosing between 5keV and 30keV by which one reaches the required sensitivity in less dwell time is determining the landing energy based on optimization of the acquisition time).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to have modified Sugie’s controller in view of Mukhtar to include determining the integrated frame number (acquisition time) from the characteristics of the wafer stack and from BSE signals of line features 211 and space features 212 as taught in Sugie, expressed as BSE yields according to Mukhtar’s sensitivity relation; and set the acceleration voltage 1002, taught in Sugie pg. 7, to the landing energy that reaches the required sensitivity with the shortest acquisition time. One of ordinary skill in the art would be motivated to make such modification to calculate the sensitivity measurements of buried features versus electron dosage for any array of electron beam voltages (Mukhtar pg. 1) and to access the sensitivity of buried features versus electron dosage (Mukhtar pg. 2).
16. Regarding claim 11:
The modified invention above teaches the non-transitory computer readable medium of claim 10. Sugie does not specifically teach wherein the plurality of characteristics of the wafer stack comprise a density or an atomic number of materials in the wafer stack.
Mukhtar teaches wherein the plurality of characteristics of the wafer stack comprise a density or an atomic number of materials in the wafer stack (pg. 3 teaches that the contrast between Si and SiO2 under SiO2 is weak, while contrast between Cu and SiO2 is much better (Z and density are considerably different) so that individual Cu lines can be resolved under up to 100nm of SiO2).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to have modified Sugie in view of Mukhtar to include that the plurality of characteristics of the wafer stack comprise a density or an atomic number of materials in the wafer stack. One of ordinary skill in the art would be motivated to make such modification because the atomic number and density of the buried line and the surrounding material determine how readily the buried line can be resolved, ensuring that the acquisition time is sufficient for the materials of the particular stack being measured (Mukhtar pg. 3-4).
17. Regarding claim 12:
The modified invention above teaches the non-transitory computer readable medium of claim 10. Sugie does not specifically teach wherein the plurality of characteristics of the wafer stack comprise geometries or dimensions of the plurality of features on the wafer stack.
Mukhtar teaches wherein the plurality of characteristics of the wafer stack comprise geometries or dimensions of the plurality of features on the wafer stack (pg. 3 teaches that buried lines have defined dimensions where the gratings are 40nm in height, 10nm in width, and a pitch of 30nm. Figs. 9-10 shows separate sensitivity-vs-dwell-time curve for each burial depth, and the needed dwell time changes sharply with depth. For Au at 5keV, a sensitivity of about 2 is reached in about 50ns when the lines are buried 10nm deep, but takes about 1000 ns when they are buried 40nm deep (fig. 9). The dwell time is therefore determined based on the dimensions of the buried line features).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to have modified Sugie in view of Mukhtar to include that wherein the plurality of characteristics of the wafer stack comprise geometries or dimensions of the plurality of features on the wafer stack. One of ordinary skill in the art would be motivated to make such modification to ensure that the acquisition time is sufficient for the particular buried pattern being measured (Mukhtar pg. 7-8).
18. Regarding claim 13
The modified invention above teaches the non-transitory computer readable medium of claim 12. Sugie further teaches that wherein the plurality of features include a set of buried line features (pg. 4 teaches that the lower layer pattern is a line pattern formed under the film to be etched (organic film, insulating film, etc)). Sugie does not specifically teach that wherein the dimensions of the buried line features include a pitch.
Mukhtar teaches that wherein the dimensions of the buried line features include a pitch (pg. 3 teaches that the gratings are 40nm in height, 10nm in width, and a pitch of 30nm. Pg. 1 and figs. 6-10 teaches computing the sensitivity-vs-dwell-time curves for 10nm line/space gratings. A line/space designation specifies the width of each line and the spacing between adjacent lines, which together define the pitch. The instant specification defines pitch the same way ([0063] instant specification teaches that a pitch corresponds to a spacing between adjacent lines) Under broadest reasonable interpretation, the claim requires only that the dimension on which the acquisition time is based includes a pitch).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to have modified Sugie in view of Mukhtar to include that wherein the dimensions of the buried line features include a pitch. One of ordinary skill in the art would be motivated to make such modification so that the sensitivity and acquisition time is computed for a grating matching the buried line pattern being measured (Mukhtar pg. 1, 3-4).
19. Claims 6, 8-9, 15 are rejected under 35 U.S.C 103 as being unpatentable over Sugie in view of Mukhtar, further in view of Van den Broek, W., Van Aert, S., Goos, P., & Van Dyck, D. (2011). Throughput maximization of particle radius measurements through balancing size versus current of the electron probe. Ultramicroscopy, 111(7), 940–947. https://doi.org/10.1016/j.ultramic.2010.11.025. [hereinafter Van den Broek].
20. Regarding claim 6:
The modified invention above teaches the system of claim 1. Sugie in view of Mukhtar does not specifically teach that wherein the acquisition time is further determined based on one or more hardware parameters related to a detector efficiency.
Van den Broek teaches that wherein the acquisition time is further determined based on one or more hardware parameters related to a detector efficiency (pg. 940 teaches determining the recording time needed to measure a feature to a prespecified precision. Pg. 942 section 2.2 teaches a factor
γ
1
accounting for the percentage of electrons in the beam that are counted at the detector. This means that
γ
1
accounts for the particle’s atomic number, the detector geometry and the detector’s efficiency. The detector geometry and detector efficiency are hardware parameters related to a detector efficiency. Pg. 944 Eq. (28) teaches that the measurement precision depends on
γ
1
together with the beam current I and the recording time
τ
0
.
σ
C
R
2
, defined as the precision on pg. 943, is affected by
γ
1
and
τ
0
).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to have modified Sugie in view of Mukhtar further in view of Van den Broek to include that wherein the acquisition time is further determined based on one or more hardware parameters related to a detector efficiency. Accounting for detector efficiency ensures that the acquisition time is long enough to reach the required precision with the detector actually used, while giving the minimum required recording time needed to reach that precision (Van den Broek pg. 940).
21. Regarding claim 8:
The modified invention above teaches the system of claim 1. Sugie in view of Mukhtar does not specifically note that wherein the controller includes circuitry configured to cause the system to further perform: determining the one or more parameters including a beam current of the e-beam based on optimization of the acquisition time for the overlay measurement.
Van den Broek teaches determining the one or more parameters including a beam current of the e-beam based on optimization of the acquisition time (pg. 940 abstract teaches that the size and the corresponding current of the electron probe determine the precision of the estimate. Pg. 940 then teaches that selecting the probe size, and with it the corresponding beam current, by minimizing the recording time. Given a prespecified precision of the estimates of R, we seek the probe size that yields the minimum required recording time needed to reach that precision. Van den Broek therefore determines the probe current based on optimization of the recording time (acquisition time)).
Sugie teaches that a probe current 1003 is a parameter used for the overlay measurement (Sugie fig. 10, pg. 7). Mukhtar then teaches that sensitivity for buried overlay features depends on the electron dosage (I_B*τ)/e) (Mukhtar pg. 4). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to have modified Sugie in view of Mukhtar, further in view of Van den Broek to include that the controller determines the probe current 1003 of Sugie based on optimization of the acquisition time. One of ordinary skill in the art would be motivated to make such modification to seek the probe size, and with it the corresponding beam current, that yields a minimum required recording time needed (Van den Broek pg. 940).
22. Regarding claim 9:
The modified invention above teaches the system of claim 1. Sugie in view of Mukhtar does not specifically note that wherein determining the acquisition time for the overlay measurement further comprises: fitting signal measurements of the plurality of features on the wafer stack using a least squares regression analysis; and optimizing the acquisition time for the overlay measurement based on a standard deviation.
Van den Broek teaches fitting signal measurements of the plurality of features using a least squares regression analysis (pg. 940 teaches that images are treated as data planes from which structural information has to be estimated quantitatively, and the structure parameters are determined by fitting the model to the experimental data by the use of a criterion of goodness-of-fit such as least squares or maximum likelihood); and optimizing the acquisition time based on a standard deviation (pg. 943 teaches that the precision of an estimator is represented by the variance or the standard deviation of the estimates. Pg. 955 teaches setting the recording time from that precision where one can tune
τ
0
such that
σ
B
2
d
B
,
50
equals a prespecified variance on the estimates, so that the prespecified precision is reached with the lowest
τ
0
. Variance is the square of the standard deviation, so the recording time (acquisition time) is optimized based on a standard deviation).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to have modified Sugie in view of Mukhtar, further in view of Van den Broek to include that the acquisition time is determined by fitting the measured signal by least squares and optimizing the acquisition time based on a standard deviation. One of ordinary skill in the art would be motivated to make such modification because fitting a model to the measured data turns the measurement into a statistical parameter estimation problem whose precision can be computed as the variance or the standard deviation of the estimates. The acquisition time can then be set to the minimum needed to reach a certain criterion (Van den Broek pg. 940).
23. Regarding claim 15:
The modified invention above teaches the non-transitory computer readable medium of claim 10. Sugie in view of Mukhtar does not specifically teach wherein the acquisition time is further determined based on one or more hardware parameters related to a detector efficiency.
Van den Broek teaches that wherein the acquisition time is further determined based on one or more hardware parameters related to a detector efficiency (pg. 940 teaches determining the recording time needed to measure a feature to a prespecified precision. Pg. 942 section 2.2 teaches a factor
γ
1
accounting for the percentage of electrons in the beam that are counted at the detector. This means that
γ
1
accounts for the particle’s atomic number, the detector geometry and the detector’s efficiency. The detector geometry and detector efficiency are hardware parameters related to a detector efficiency. Pg. 944 Eq. (28) teaches that the measurement precision depends on
γ
1
together with the beam current I and the recording time
τ
0
.
σ
C
R
2
, defined as the precision on pg. 943, is affected by
γ
1
and
τ
0
).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention to have modified Sugie in view of Mukhtar further in view of Van den Broek to include that wherein the acquisition time is further determined based on one or more hardware parameters related to a detector efficiency. Accounting for detector efficiency ensures that the acquisition time is long enough to reach the required precision with the detector actually used, while giving the minimum required recording time needed to reach that precision (Van den Broek pg. 940).
Conclusion
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/LARRY LI/
Examiner, Art Unit 2881
/MICHAEL J LOGIE/Primary Examiner, Art Unit 2881
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