DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Drawings
The drawings are objected to under 37 CFR 1.83(a) because they fail to show “2602” as described in the specification (See Spec. para. [0072] “lateral edge 2602” and para. [0084] “lateral position of the edge 2602”.
Any structural detail that is essential for a proper understanding of the disclosed invention should be shown in the drawing. MPEP § 608.02(d). Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Specification
The disclosure fails to meet requirements forth in 37 C.F.R. 1.52 (b)(6) for the following reasons:
Paras. [001]-[009] each has a paragraph number contains three numerals.
The paragraph between paras. [0069] and [0070] is not numbered.
The disclosure is objected to because of the following informalities:
Para. [0084] states “A non-limitative example of acquisition signal 400 is illustrated in Fig. 4A. Assume that the acquisition signal 400… depicted in Fig. 2A… As visible in Fig. 4A … At position 271 which corresponds to the position of the lateral edge 2601…”, however, Figs.2A does not include a “lateral edge 2601”;
Para. [0085] states “Fig. 4B illustrates a derivative signal 450 which is the derivative (along the horizontal X axis) of the acquisition signal 400 of Fig. 4A obtained for the specimen depicted in Fig. 2A. As visible in Fig. 4B, the derivative signal 450 includes two main peaks: a first peak 460 is located at the position of the lateral edge 2501 of the first layer 210….”, however, Figs.2A does not include a “lateral edge 2501”;
Para. [0089] states “Assume that the second layer is located at a deeper location (along the height axis Z of the specimen) than the first layer, and that the second layer is covered by the first layer, as illustrated in Fig. 2A”, however, Fig. 2A does not illustrate such an embodiment (i.e., in Fig. 2A, the second layer is not covered by the first layer).
Claim Rejections - 35 USC § 101
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 therefor, subject to the conditions and requirements of this title.
Claims 1-20 are rejected under 35 U.S.C. 101 because the claimed invention is directed to an abstract idea (i.e., mental processes and mathematical concepts for analyzing data), and the claims do not recite additional elements that integrate the abstract idea into a practical application or amount to significantly more than the judicial exception.
Step 2A, Prong One – Judicial exception (Abstract Idea)
The courts consider a mental process (thinking) that “can be performed in the human mind, or by a human using a pen and paper” to be an abstract idea. CyberSource Corp. v. Retail Decisions, Inc., 654 F.3d 1366, 1372, 99 USPQ2d 1690, 1695 (Fed. Cir. 2011). As the Federal Circuit explained, “methods which can be performed mentally, or which are the equivalent of human mental work, are unpatentable abstract ideas the ‘basic tools of scientific and technological work’ that are open to all.’” 654 F.3d at 1371, 99 USPQ2d at 1694 (citing Gottschalk v. Benson, 409 U.S. 63, 175 USPQ 673 (1972)). See also Mayo Collaborative Servs. v. Prometheus Labs. Inc., 566 U.S. 66, 71, 101 USPQ2d 1961, 1965 ("‘[M]ental processes[] and abstract intellectual concepts are not patentable, as they are the basic tools of scientific and technological work’" (quoting Benson, 409 U.S. at 67, 175 USPQ at 675)); Parker v. Flook, 437 U.S. 584, 589, 198 USPQ 193, 197 (1978) (same). Further, the courts do not distinguish between claims that recite mental processes performed by humans and claims that recite mental processes performed on a computer. As the Federal Circuit has explained, "[c]ourts have examined claims that required the use of a computer and still found that the underlying, patent-ineligible invention could be performed via pen and paper or in a person’s mind." Versata Dev. Group v. SAP Am., Inc., 793 F.3d 1306, 1335, 115 USPQ2d 1681, 1702 (Fed. Cir. 2015). See also Intellectual Ventures I LLC v. Symantec Corp., 838 F.3d 1307, 1318, 120 USPQ2d 1353, 1360 (Fed. Cir. 2016) (‘‘[W]ith the exception of generic computer-implemented steps, there is nothing in the claims themselves that foreclose them from being performed by a human, mentally or with pen and paper.’’); Mortgage Grader, Inc. v. First Choice Loan Servs. Inc., 811 F.3d 1314, 1324, 117 USPQ2d 1693, 1699 (Fed. Cir. 2016) (holding that computer-implemented method for "anonymous loan shopping" was an abstract idea because it could be "performed by humans without a computer").
In the instant case, the independent claims recite limitations that, when considered in their broadest reasonable interpretation, fall within the abstract idea of (i) mental process (concepts formed in the human mind such as observation, evaluation, and judgment) and/or (ii) mathematical concepts (relationships, comparisons, and mathematical operations such as determining variations/derivatives, comparing amplitudes/widths/slopes, and selecting based on criterial). For instance, the independent claim 1 recites (independent claims 16 and 19 recite similar limitations):
obtain an acquisition signal informative of a semiconductor specimen comprising at least a first layer located at a first depth in the specimen, and a second layer located at a second depth in the specimen, higher than the first depth,
enabling generating, in at least one of the acquisition signal or in a signal derived from the acquisition signal, a first pattern informative of a lateral edge of the first layer, and a second pattern informative of a lateral edge of the second layer, wherein the second pattern differs from the first pattern, and
use at least one of the acquisition signal or the signal derived from the acquisition signal, to determine one or more properties of at least one of the first layer or the second layer.
These limitations collectively recite analyzing measurement data by applying comparisons/relationships (including derivative/variation analysis) to infer layer edge locations properties and select landing energy. Such evaluation and selection is fundamentally a form of data analysis and mathematical evaluation that can be characterized as an abstract idea.
Step 2A, Prong Two – Integration into a Practical Application
The claims are not integrated into a practical application because in practice, executing all of the steps is indistinguishable from: (i) mere data acquisition from a conventional instrument environment, and (ii) generic computer implementation of the abstract analysis. That is to say that integration into a practical application is lacking where, as here, the abstract idea has no effect on the material world or the execution of the process.
Although the claims include additional elements (e.g., “one or more processing circuities,” “electron beam examination system tool,” a “semiconductor specimen” with layers), these additional elements do not integrate the abstract idea into a practical application. For example, the electron beam examination system/tool and acquisition signal limitations function as data gathering steps without reciting a specific improvement to the electron beam tool itself, the scan hardware, or the signal formation mechanism, but instead recites post-acquisition analysis and interpretation of an acquired signal using generic processing circuitry. Likewise, the recited “processing circuitry” performs generic functions such as obtain/determine/compare/identify/select, which amounts to using a computer as a tool to perform the abstract data analysis more quickly or efficiently.
Therefore, the claims as a whole are directed to an abstract idea.
Step 2B– Significant More (Inventive Concept)
The claims do not include additional elements, either individually or as an ordered combination, that amount to significant more than the abstract idea. The “processing circuitries” (recited in claims 1, 16, 19-20), the “ non-transitory computer readable medium” (recited in claim 20) limitations are generic computer elements performing routine functions such as receiving and processing data. The “electron beam examination system/tool” (recited in claims 1, 11, 15-16) and acquiring signals at landing energies are conventional measurement activities used as input to the abstract analysis. As such, the recited system is a well-known system and a routine part of data acquisition and analyzing, and the addition of the system is done at such a high level of generality that the claimed system would effectively prevent anyone using any system from thinking the claimed abstract idea.
Dependent claims 2-8, 14, 17, 18, and 20 include additional limitations (e.g., derivative signals, using expected amplitudes, using width/amplitude/slope differences) merely add further details of the abstract analysis, and as such not overcome the above noted issues.
Dependent claims 9-13 add “landing energy selection using simulations” limitations yet still amount to evaluating and selecting based on mathematical relationships and comparisons of data patterns. Tying this evaluation to the SEM context, without more, is an invocation of a technological environment rather than a practical application that meaningfully limits the abstract idea.
Dependent claim 15 adds an “electronic beam” to the invention. Adding an electronic beam to the claimed abstract idea does not meaningfully limit the claim, since the electronic beam only acts as a nominally claimed data-gathering step in the larger context of an abstract idea.
Taken alone or as ordered combination, claims 1-20 fail to recite patent eligible subject matter.
Claim Objections
Claim 6 is objected to because the following informalities: “…based on a determination that that data informative…” includes an extra “that”.
Claim 8 is objected to because of the following informalities: “the second layer is separated by the first layer by a layer …” should be “the second layer is separated from the first layer by a layer …”
Appropriate correction is required.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1-18 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Independent Claims 1 and 16 each recites that the semiconductor specimen includes “a first layer located at a first depth in the specimen, and a second layer located at a second depth in the specimen, higher than the first depth.” However, dependent claims 6 and 7 (both dependent on claim 1) recite that “the second layer is located deeper in the specimen than the first layer.” The term “depth” ordinarily relates to distance below a surface, such that “deeper” indicates a greater depth, whereas “higher than” may be reasonably interpreted as indicating either a greater depth value or a position closer to the surface (higher elevation). In addition, where applicant acts as his or her own lexicographer to specifically define a term of a claim contrary to its ordinary meaning, the written description must clearly redefine the claim term and set forth the uncommon definition so as to put one reasonably skilled in the art on notice that the applicant intended to so redefine that claim term. Process Control Corp. v. HydReclaim Corp., 190 F.3d 1350, 1357, 52 USPQ2d 1029, 1033 (Fed. Cir. 1999). As such, even if the term “higher” in claim 1 is used by the claim to mean “located closer to the bottom of the specimen”, because the accepted meaning is “a position closer to the surface of the specimen”, the term is indefinite because the specification does not clearly redefine the term. Because the claims recite a term contrary to its ordinary meaning and/or recites an inconsistent relationship between the first and second depths/layers (“higher than” versus “deeper”), the metes and bounds of the claimed subject matter are not reasonably certain; a person of ordinary skill in the art would not be informed with reasonable certainty whether the claimed “second depth” is intended to be greater than or less than the “first depth.”
Claim 6 recites the limitation “a pattern of the signal”. There is insufficient antecedent basis for this limitation in the claim. Claim 1 introduces “acquisition signal” and “signal derived…,” it is not clear the “signal” in claim 6 refers to the acquisition signal or the derived signal in claim 1, or a different type of signal.
Claim 7 recites that the system identifies that one signal pattern corresponds to a lateral edge of the first layer and another signal pattern corresponds to a lateral edge of the second layer based on a determination that data informative of an amplitude of said another pattern is larger than data informative of an amplitude of said pattern. However, the specification describes the amplitude relationship between peaks corresponding to different-depth layers in a manner that is internally inconsistent. In one passage, the specification states that for a deeper/bottom layer “it is expected that the amplitude of the peak … corresponding to the lateral edge of the second layer … will be larger than the expected amplitude … corresponding to the lateral edge of the first layer … closer to the surface.” Yet, the specification further describes an example in which “the second peak … has a smaller amplitude than … the first peak,” and indicates that this smaller-amplitude peak corresponds to the bottom layer (See Spec. para. [0092]). Because claim 7 requires using an “amplitude … larger than” determination to assign which pattern corresponds to which layer edge, and the intrinsic record provides conflicting guidance regarding whether the deeper layer corresponds to a larger or smaller amplitude (and does not set forth a clear sign convention or unambiguous amplitude definition for the comparison), the scope of claim 7 is not reasonably certain to a person of ordinary skill in the art.
Claim Rejections - 35 USC § 102
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.
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
Claims 1-2 are is/are rejected under 35 U.S.C. 102a (1) as being anticipated by US 2021/0383529 A1 [hereinafter Kris].
Regarding Claim 1:
Kris teaches a system comprising one or more processing circuitries (para. [0015]): “A system ...comprise at least one processor configured for performing metrology) configured to:
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obtain an acquisition signal informative of a semiconductor specimen comprising at least a first layer located at a first depth in the specimen, and a second layer located at a second depth in the specimen, higher than the first depth (annotated Fig. 4a and Fig. 4b; paras. [0013, 0020, 0124, 0127]: obtaining SEM measurement data for a 3D-VNAND staircase having plural steps in a vertically tiered/multilayer structure; the measurement data is represented as a 1-D SEM signal/profile where “the vertical axis… comprises SEM signal intensity” and “the horizontal axis may be the x-SEM image coordinate”; for example, “Fig. 4b shows the SEM signal corresponding to the steps of Fig. 4a, ” under a broad reasonable interpretation, different steps correspond to different vertical levels/depths within the multilayer structure, i.e., first and second “layers” at different depths (See annotated Fig. 4a)),
wherein the acquisition signal has been acquired by an electron beam examination system operative to scan the specimen with an electron beam associated with a landing energy (paras. [0013 and 0015]: the system operates in conjunction with a SEM and acquires an image “generated by scanning the semiconductor structure with a charged particle beam and collecting signals emanating from the semiconductor structure”; an SEM electron beam that impinges on the specimen is necessarily associated with a beam energy at the specimen (landing energy), as recited),
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enabling generating in at least one of the acquisition signal or in a signal derived from the acquisition signal, a first pattern informative of a lateral edge of the first layer, and a second pattern informative of a lateral edge of the second layer, wherein the second pattern differs from the first pattern (Fig. 4b, annotated figs. 4a and 4d, paras. [0124, 0127-0130]: the 1-D SEM signal (Fig. 4b) corresponds to the staircase steps (Fig. 4a) and contains edge-related features; Fig. 4d shows coarse edges and pairs of fine edges defining left and right boundaries of each step; these step boundaries are lateral terminations/boundaries along the x-direction (i.e., “lateral edges”) and appear in/are extracted from the 1-D SEM signal (or a signal derived therefrom). Different steps (different layer levels under BRI) have different corresponding boundary patterns (at minimum at different x-positions), such that the second pattern differs from the first pattern), and
use at least one of the acquisition signal or the signal derived from the acquisition signal, to determine one or more properties of at least one of the first layer or the second layer (paras. [0054, 0131, 0133]: processing the SEM image/signal of the staircase for metrology control, including measuring one or more steps as an individual feature and using the detected fine edges/boundaries for CD results such as estimating distances between fine contours/boundaries (dimensional properties), thereby determining one or more properties of the measured step/layer level).
Regarding Claim 2:
Claim 2 includes four clauses linked by “or,” and examiner relied on the first and second clauses.
Kris teaches the system of claim 1. Kris further teaches wherein the one or more properties include at least one of a position of the lateral edge of the first layer or a position of the lateral edge of the second layer (annotated Fig. 4d and paras. [0124, 0130]: the SEM graph has an x-SEM image coordinate as the horizontal axis, and Fig. 4d shows “pairs of fine edges … defining left and right boundaries … of each step,” and these boundaries are used for CD results. Thus, Kris identifies the locations (positions along x) of the step boundaries (lateral edges) in the acquisition signal or a signal derived therefrom).
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 (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.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 3, and 14-18 are rejected under 35 U.S.C. 103 as being unpatentable over Kris in view of Villarrubia et al., Simulation study of repeatability and bias in the critical dimension scanning electron microscope. Journal of Micro/Nanolithography, MEMS, and MOEMS, 4(3), 033002 (2005) [hereinafter Villarrubia 2005].
Regarding Claim 3:
Claim 3 includes two clauses linked by “or,” and examiner relied on the second (slope) clause.
Kris teaches the system of claim 1. Kris further teaches a first pattern informative of a lateral edge of a first layer and a second pattern informative of a lateral edge of a second layer. However, Kris does not specifically note a first slope and a second slope informative of the lateral edge of a first layer and the lateral edge of a second layer.
Villarrubia 2005 teaches determining an edge position on a linescan using a maximum-derivative / maximum-slope rule (i.e., in a derived/variation signal, the claimed “pattern” corresponds to the maximum-derivative/maximum-slope feature used to assign the edge location). Specifically, Villarrubia 2005 teaches a first pattern corresponds to a first slope informative of a first edge, a second pattern corresponds to a second slope informative of a second edge, wherein the first slope differs from the second slope ( Pages 5 of 10- Section 2.5: teaches “The maximum derivative method assigns the edge position … where the magnitude of the slope is greatest,” and further explains that the “noisy peaked curve is a linescan centered on the … edge,” the slope/derivative operation is performed on that peak/linescan shape, and that edge-related peaks can have different shapes/widths depending on edge characteristics (e.g., “an edge with a vertical sidewall exhibits a narrower intensity peak than does an edge with a sloped sidewall”), which necessarily corresponds to different slopes on the peak’s outside half where the edge is assigned under the maximum-derivative method).
Kris teaches SEM/CD metrology of staircase steps using a 1-D SEM signal/profile (SEM signal intensity versus x-position) in which edge-related patterns are present and used for measurement, while Villarrubia 2005 teaches a known CD-SEM edge-position assignment technique for such 1-D linescans based on the maximum-derivative/maximum-slope criterion. Therefore, it would have been obvious for an ordinary skilled person in the art, before the effective time of filing, to apply Villarrubia 2005’s linescan method to Kris’s 1-D SEM signal to yield (for each edge-pattern in Kris) a corresponding slope-based pattern (signature) informative of that lateral edge. A POSITA performing SEM-based CD/metrology using a 1-D SEM linescan as in Kris would therefore look to apply Villarrubia 2005’ s known derivative/slope-based edge-assignment technique to obtain a consistent, repeatable edge-location determination from the same type of input signal (SEM intensity vs position), with a reasonable expectation of success because Villarrubia 2005’s method is expressly directed to edge assignment in such SEM linescan.
Regarding Claim 14:
Kris teaches the system of claim 1. However, Kris does not specifically note that obtain a first/second expected amplitude for the first/second pattern and identifying the first/second pattern based on this first/second expected amplitude.
Villarrubia 2005 teaches obtain an expected amplitude for a pattern and identifying the pattern based on this expected amplitude (Fig. 4 and Page 3 of 10- Section 2.3: calculating a simulated linescan in which the intensity at each point on the linescan (i.e., the signal level of the simulated linescan versus position) is determined by modeled secondary-electron emission, stating that “the total number of secondary electrons emitted from the sample at each beam position determines the intensity at the corresponding point on the linescan,” and further shows (Fig.4) a “match between simulated and measured linescans,” thereby providing an expected (predicted) signal level profile for a linescan pattern).
Kris teaches the measured SEM signal intensity-versus-position profile containing the first pattern. Villarrubia 2005 teaches a simulated linescan intensity vs position profile that supplies an expected (predicted) signal level for the corresponding pattern. Therefore, it would have been obvious for an ordinary skilled person in the art, to use Villarrubia 2005’s simulated linescan as a reference for Kris’s measured SEM linescan, such that a “pattern” in the acquisition signal has a measurable signal level (magnitude) in the SEM signal intensity profile, in order to provide an expected signal level profile for identifying edge-related patterns in the measured SEM signal.
Regarding Claim 15:
Kris teaches the system of claim 1.
Kris further teaches the specimen includes N vertically stacked layers L1 to LN, with N≥2, wherein each layer has a different width (a VNAND / 3D NAND structure with plural vertically stacked layers and a staircase having plural steps, for example, Fig. 4a shows a structure with 3 vertical levels and each level has a different width), wherein the system is configured to:
obtain an acquisition signal informative of the specimen, wherein the acquisition signal has been acquired by an electron beam examination system operative to scan the specimen with an electron beam (obtaining an SEM acquisition signal/profile for the staircase steps with a SEM system, stating “FIG. 4b shows the SEM signal corresponding to the steps”)
determine data informative of variations of the acquisition signal (determining variation/edge information from the SEM signal for step detection and metrology, including use of an “edge width parameter” in the context of “step detection” in the SEM signal corresponding to the steps), and
use the data to determine one or more properties of at least one of the layers L1 to LN (using measured fine edges to generate dimensional metrology results for each step).
However, Kris does not specifically note that the specimen is scanned with an electron beam associated with a width which expands from a depth of a layer Li to a depth of the next layer Li+1, with i from 1 to N-1.
Villarrubia 2005 teaches the specimen is scanned with an electron beam associated with a width which expands from a depth of a layer Li to a depth of the next layer Li+1, with i from 1 to N-1 (Page 3 of 10- Section 2.2: the effective spot/beam width can be larger at deeper locations than at shallower locations, stating that certain conditions “correspond respectively to spot sizes 10 nm and 20 nm larger at the bottom of the line than at the top” ).
Kris teaches CD-SEM metrology on vertically stacked staircase structures using SEM signal profiles of the steps. Villarrubia 2005 addresses CD-SEM linescan behavior and teaches that effective spot size can increase from top to bottom due to depth-of-focus/beam distribution. Therefore, it would have been obvious for an ordinary skilled person in the art, before the effective time of filing, to apply Villarrubia 2005’s depth-dependent spot-size behavior in Kris’s multilayer staircase scanning context to account for the beam width expansion with depth when determining step/edge measurements across layers, in order to improve measurement reliability/accuracy across layers (i.e., to address depth-dependent changes in resolution/edge response).
Regarding Claim 16:
Kris teaches a system comprising one or more processing circuitries (para. [0015]): “A system ...comprise at least one processor configured for performing metrology) configured to:
obtain at least one acquisition signal informative of a semiconductor specimen comprising at least a first layer located at a first depth in the specimen, and a second layer located at a second depth in the specimen, higher than the first depth (annotated Fig. 4a and Fig. 4b: paras. [0013, 0020, 0124, 0127]:obtaining SEM measurement data for a 3D/VNAND staircase having plural steps in a vertically tiered/multilayer structure; the measurement data is represenetd as a 1-D SEM signal/profile where “the vertical axis… comprises SEM signal intensity” and “the horizontal axis may be the x-SEM image coordinate”; for example, “Fig. 4b shows the SEM signal corresponding to the steps of Fig. 4a, ” and that the image/signal is indicative of at least two individual fabrication steps in the staircase, under a broad reasonable interpretation, different steps correspond to different vertical levels/depths within the multilayer structure, i.e., first and second “layers” at different depths (Fig. 4a)),
wherein the at least one acquisition signal has been acquired by an electron beam examination tool operative to scan the specimen with an electron beam associated, in at least part of the scan of the specimen (paras. [0013 and 0015]: the system operates in conjunction with a SEM and acquires an image “generated by scanning the semiconductor structure with a charged particle beam and collecting signals emanating from the semiconductor structure”), and
use at least one of the acquisition signal, or a signal derived from the acquisition signal, to determine one or more properties of at least one of the first layer or the second layer (paras. [0054, 0131, 0133]: processing the SEM image/signal of the staircase for metrology control, including measuring one or more steps as an individual feature and using the detected fine edges/boundaries for CD results such as estimating distances between fine contours/boundaries (dimensional properties), thereby determining one or more properties of the measured step/layer level).
However, Kris does not specifically note that the electron beam associated with a width which is larger at the second depth than at the first depth.
Villarrubia 2005 teaches the electron beam associated a width which is larger at the second depth than at the first depth (Page 3 of 10- Section 2.2: the effective spot/beam width can be larger at deeper locations than at shallower locations, stating that certain conditions “correspond respectively to spot sizes 10 nm and 20 nm larger at the bottom of the line than at the top”).
Kris teaches CD-SEM metrology on vertically stacked staircase structures using SEM signal profiles of the steps, while Villarrubia 2005 is directed to CD-SEM linescan modeling and explicitly teaches that the effective landing spot/beam width can be larger at a deeper location (“bottom”) than at a shallower location (“top”) due to instrument/beam conditions. Therefore, it would have been obvious for an ordinary skilled person in the art, before the effective time of filing, to operate Kris’s SEM acquisition under the known depth-dependent spot-size condition taught by Villarrubia 2005 so that SEM signals collected from features at different depths within the stacked structure are interpreted and measured with appropriate consideration of the beam width change with depth, thereby improving accuracy/consistency of edge/dimension metrology across layers.
Regarding Claim 17:
The second “wherein” clause in Claim 17 includes three sub-clauses linked by “or,” and examiner relied on the first (width) sub-clause.
Kris in view of Villarrubia 2005 teaches the system of claim 16.
Kris further teaches:
said electron beam enables generating, in the acquisition signal, or the signal derived from the acquisition signal, a first pattern informative of a lateral edge of the first layer, and a second pattern informative of a lateral edge of the second layer (Figs.4a, 4b, annotated fig. 4d, paras. [0124, 0127-0130]: the 1-D SEM signal (Fig. 4b) corresponds to the staircase steps (Fig. 4a) and contains edge-related features; Fig. 4d shows coarse edges and pairs of fine edges defining left and right boundaries of each step; these step boundaries are lateral terminations/boundaries along the x-direction (i.e., “lateral edges”) and appear in/are extracted from the 1-D SEM signal (or a signal derived therefrom). Different steps (different layer levels under BRI) have different corresponding boundary patterns (at minimum at different x-positions), such that the second pattern differs from the first pattern).
Villarrubia 2005 further teaches:
data informative of a width of the second pattern is larger than data informative of a width of the first pattern (Pages 3 and 5 of 10- Sections 2.2 and 2.5: during SEM/CD-SEM linescan, the edge-generated intensity peak has a finite width and that variables affect the width of the peak being fit “bright image peaks produced by the line’s edges have a finite width …” “Some of the variables in our study affect the width of the peak that is being fit …”).
Therefore, when the system of Kris (having first/second edge patterns in the linescan) is operated/configured under the condition that the effective scan width is larger at the second depth than the first, Villarrubia 2005 supports that the corresponding edge peak/pattern width is affected by that width condition, yielding data informative of a larger width for the pattern associated with the larger effective width condition.
Regarding Claim 18:
Claim 18 includes three clauses linked by “or” for its determination step, and examiner relied on the third (slope) clause.
Kris in view of Villarrubia 2005 teaches the system of claim 16.
Kris further teaches perform a determination of at least one of a position of the lateral edge of the first layer or a position of the lateral edge of the second layer (fine edges defining boundaries “may be used for CD results” (i.e., determining edge locations/positions used for dimensional measurement).
Villarrubia 2005 further teaches identifying at least one of the first pattern or the second pattern based on data informative of a slope of the first pattern and data informative of a slope of the second pattern (Page 5 of 10- Section 2.5: identifying/assigning an edge position on a linescan peak using a maximum-slope / maximum-derivative rule “The maximum derivative method assigns the edge position … where the magnitude of the slope is greatest”).
As such, applying Villarrubia 2005’s slope-based edge assignment technique to Kris’s 1-D SEM signal patterns provides the required “identifying … based on … slope” step, as part of determining the position of at least one of the lateral edges.
Claims 4-6 are rejected under 35 U.S.C. 103 as being unpatentable over Kris in view of Mack et al., Analytical linescan model for SEM metrology. Proceedings of SPIE (2015) [hereinafter Mack].
Regarding Claim 4:
Kris teaches the system of claim 1. Kris further teaches the first pattern informative of the lateral edge of the first layer located at the first depth in the specimen and the second pattern informative of the second layer located at the second depth in the specimen, higher than the first depth (see claim 1 rejection). However, Kris does not specifically note a relationship between data informative of a shape of the first pattern and of the second pattern and a depth within the specimen, and use that relationship to differentiate the first and the second patterns.
Mack is directed to SEM metrology and develops an analytical 1-D SEM linescan model for an isolated edge, in which the observed edge-related linescan response is parameterized and correlated to physical step geometry. Specifically, Mack teaches a relationship between data informative of a shape of patterns and a depth within the specimen (Page 5 of 23- Section 3: “the backscatter range parameter σb varies linearly with step height” and that “taller steps influence the linescan out to a distance away from the edge about equal to the step height”).
Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective time of filing, to configure the Kris system to use the known relationship (from Mack) between edge-pattern shape/extent in a 1-D SEM linescan and vertical dimension (depth/height) to differentiate which detected fine-edge pattern corresponds to the edge associated with the shallower layer versus the deeper layer. A POSITA would be motivated to use Mack’s height-dependent width behavior to distinguish Kris’s edge patterns by step depth, with a reasonable expectation of success since both relate SEM profile shape to step geometry.
Regarding Claim 5:
Claim 5 includes two clauses selectable by the preamble “at least one of” language and examiner relied on the first (width) clause.
Kris teaches the system of claim 1. Kris further teaches use a first pattern informative of a lateral edge of the first layer, and a second pattern informative of a lateral edge of the second layer to determine the position of the first lateral edge of the first layer and the second lateral edge of the second layer (as discussed in previous analysis)
However, Kris does not specifically note the first/second pattern include data informative of width.
Mack teaches data informative of a width and the difference between the width values is used to identify edges (Pages 5 and 6 of 23: an edge/step produces a linescan response having a measurable lateral extent (width/extent in x) and that this extent can be expressed as how far from the edge the linescan is influenced, stating “Taller steps influence the linescan out to a distance away from the edge about equal to the step height …”)
Therefore, it would have been obvious for an ordinary skilled person in the art, before the effective time of filing, to perform SEM staircase metrology as in Kris by applying Mack’s known teaching that step/edge linescan responses have a measurable lateral extent/width to use width differences as an additional, predictable discriminator for identifying which edge-related pattern corresponds to which layer edge, to improve reliable edge identification across staircase levels.
Regarding Claim 6:
Kris teaches the system of claim 1.
Kris further teaches:
wherein the second layer is located deeper in the specimen than the first layer (Fig. 4a shows the second step has a further depth (i.e., further from the surface) than the first step),
wherein the system is configured to identify that a pattern of the signal corresponds to the first pattern informative of the lateral edge of the first layer and that another pattern of the signal corresponds to the second pattern informative of the lateral edge of the second layer based on a determination (as discussed in previous analysis).
However, Kris does not specially note that such a determination is based on a width difference included in the data information.
Mack teaches identify different patterns of the signal correspond to the lateral edges based on a determination that that data informative of a width of one pattern is larger (Pages 5-6: teaches the directional relationship that increased step height corresponds to a larger lateral extent/width of the edge-related linescan response, stating “Taller steps influence the linescan out to a distance away from the edge about equal to the step height …”).
Therefore, it would have been obvious for an ordinary skilled person in the art, before the effective time of filing, to incorporate Mack’s width/extent characterization into Kris’s edge-pattern analysis to provide a predictable basis for associating patterns from different steps levels (shallower vs deeper) using relative width difference.
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Kris in view of Arat et al., Estimating Step Heights from Top-Down SEM Images. Microscopy and Microanalysis, 25(4), 903–911 (2019) [hereinafter Arat].
Regarding Claim 7:
Kris teaches the system of claim 1.
Kris further teaches:
wherein the second layer is located deeper in the specimen than the first layer (as previously discussed),
wherein to identify that a pattern of the signal corresponds to the first pattern informative of the lateral edge of the first layer and that another pattern of the signal corresponds to the second pattern informative of the lateral edge of the second layer based on a determination (as previously discussed).
However, Kris does not specially note that such a determination is based on an amplitude difference included in the data information.
Arat teaches identify different patterns of the signal correspond to the lateral edge based on a determination that that data informative of an amplitude of one pattern is larger (Page 3 of 9 (re Fig. 3), Page 7 of 9- Experiments: “more electrons intersect with the sidewall of the 500 nm step edge, leading to a larger signal intensity at 10 keV,” “at higher energies the higher step gives a larger signal”)
Therefore, it would have been obvious for a person of ordinary skill in the art, before the effective time of filing, to configure the processor of Kris (already identifies multiple edge-associated patterns in the SEM signal) to further compare amplitude / signal-intensity data of the respective patterns (as shown by Arat) and use that comparison to distinguish which pattern corresponds to the deeper/lower step (layer level) versus the shallower/higher step (layer level), i.e., by determining that one pattern has a larger amplitude than the other, to provide a predictable basis for associating patterns from different steps levels (shallower vs deeper) using relative amplitude difference.
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Kris in view of US20110147948A1 [hereinafter Chen].
Regarding Claim 8:
Kris teaches the system of claim 1. However, Kris does not specifically note that wherein the second layer is separated by the first layer by a layer which has a density which is smaller than a density of the first layer and than a density of the second layer. Chen teaches the second layer is separated by the first layer by a layer which has a density which is smaller than a density of the first layer and than a density of the second layer (claims 1 and 14:: teaches a porous low-k layer structure has three layers (from top to bottom) as top portion, body portion and bottom portion, “a porous bottom portion and a body portion… wherein… the porous bottom portion has a density higher than a density of the body portion,” “further comprising a top portion… located on the body portion and has a density higher than the density of the body portion”).
Kris teaches obtaining and processing a SEM-derived signal/profile for metrology of a semiconductor specimen having vertically varying structure, where the steps represent different vertical levels within the specimen. Chen teaches a semiconductor dielectric layer stack formed on a substrate and used in an interconnect structure, where a body portion is between a top portion and a bottom portion, and each of the top and bottom portions has a density higher than the density of the body portion. Thus, it would have been obvious for an ordinary skilled person in the art, before the effective time of filing, to apply Kris’s SEM-metrology system to a semiconductor specimen having the density-ranked three-layer configuration taught by Chen, resulting in a system that operates on a specimen where the first and second layers are separated by an intermediate layer whose density is smaller than the densities of both the first and second layers, as applying a known SEM/CD metrology approach to a known multilayer semiconductor stack to yield predictable result.
Claims 9-13, and 19-20 are rejected under 35 U.S.C. 103 as being unpatentable over Kris in view of Villarrubia et al., NIST Simulation of E-beam Inspection and CD-SEM in-line metrology: Final Report. NIST (2011) [hereinafter Villarrubia 2011].
Regarding Claim 9:
Kris teaches the system of claim 1. However, Kris does not specifically note that wherein the landing energy has been selected using one or more simulations.
Villarrubia 2011 teaches wherein the landing energy has been selected using one or more simulations (Pages 5 and 14 of 39: teaches optimization questions arise because there are choices in tool settings including landing energy, and a simulation framework in which beam energy is varied in a simulation loop and has application “for deciding the best landing energy to use”).
Kris teaches metrology using SEM/charged particle scan signals of VNAND staircase steps and determining dimensional results based on detected coarse/fine edges. Villarrubia 2011 teaches using simulations to support selection of operating settings for e-beam tools. Therefore, it would have been obvious for an ordinary skilled person in the art, before the effective time of filing, to combine the teachings, such that the system of Kris would select the landing energy using simulations as taught by Villarrubia 2011, because Kris’s metrology output (edge detection) depends on the quality/behavior of the SEM signal used for edge assignment, and Villarrubia 2011 teaches using simulation sweeps over beam/landing energy specifically to decide the best landing energy setting.
Regarding Claim 10:
Kris in view of Villarrubia 2011 teaches the system of claim 9.
Kris further teaches an acquisition signal or a signal derived from the acquisition signal includes a first pattern informative of the lateral edge of the first layer and a second pattern informative of the lateral edge of the second layer, wherein the first pattern differs from the second pattern (as previously discussed)
Villarrubia 2011 further teaches:
determining data informative of variations of a simulated acquisition signal of the specimen for different landing energies of the simulated acquisition signal (Pages 31-32 of 39- Section 4.3.3 and Figs. 26, 27: simulations were performed at multiple beam landing energies “Simulations were performed for… four beam landing energies from 500 eV to approximately 4.95 keV…”and obtained curves of yield vs. landing energy (i.e., the simulated signal changes as landing energy changes) “A sample of three of the resulting curves is shown in Fig. 26…” and Fig. 26 is “Secondary electron yields vs. landing energy…” also discusses different shapes of intensity profiles predicted by simulation modeling “An example of the different shapes of intensity profiles predicted… is shown in Fig. 27”), and
selecting a given landing energy for which a given simulated acquisition signal associated with this given landing energy, or a given signal derived from this given simulated acquisition signal, according to a criterion (Page 14- Section 2.2.3: such nested-loop simulations have application “for deciding the best landing energy to use for defect detection,” and by describing selection using objective criteria/cost functions as “Conditional statements… might be used to minimize user-defined cost functions (e.g., defect detection failures or CD measurement uncertainty) for solving optimization problems”).
Accordingly, applying Villarrubia 2011’s simulation-and-selection workflow to Kris’s SEM/linescan-based edge metrology yields a system that (i) determines simulated signal variations at different landing energies and (ii) selects a landing energy according to a criterion (e.g., minimizing CD measurement uncertainty / defect detection failures) while operating in the same SEM edge/step context where the first and second edge-related patterns are present in the signal used for CD metrology.
Regarding Claim 11:
Kris teaches the system of claim 1. Kris further teaches:
obtain a first/second acquisition signal informative of the specimen, wherein the first/second acquisition signal has been acquired by the electron beam examination system operative to scan the specimen with an electron beam associated with a landing energy (as previously discussed),
determine first/second data informative of variations of the first/second acquisition signal (determining variation/edge information from the SEM signal for step detection and metrology, including use of an “edge width parameter” in the context of “step detection” in the SEM signal corresponding to the steps), and
use the first/second data to determine at least one of a position of the lateral edge of the first layer or a position of the lateral edge of the second layer (determine the position of boundaries of each step based on the obtained data).
However, Kris does not specifically note that the first acquisition signal is obtained by an electron beam with a first landing energy, the second acquisition signal is obtained by an electron beam with a second landing energy, higher than the first landing energy.
Villarrubia2011 teaches:
first and second signal has been acquired by the electron beam examination system operative to scan the specimen with an electron beam associated with a first landing energy and a second landing energy, higher than the first landing energy (Page 31 of 39- Section 4.3.3: teaches performing SEM-related signal/image simulations at specified beam landing energies, including multiple landing energies spanning low-to-high values “four beam landing energies from 500 eV to approximately 4.95 keV…”), which provides a first landing energy and a second landing energy higher than the first).
Therefore, it would have been obvious for an ordinary skilled person in the art, before the time of effective filing, to obtain and use first and second dataset at different landing energies (as taught in Villarrubia 2011) as a predictable way to improve robustness/accuracy for edge-position determinization (as taught by Kris) by comparing how the profile/variation data changes with landing energy), with a reasonable expectation of success because Villarrubia 2011’s approach expressly analyzes and compares profile behavior across landing energy conditions for edge assignment.
Regarding Claim 12:
Kris teaches the system of claim 1. Kris further teaches the specimen includes N vertically stacked layers L1 to LN, with N≥2, wherein each layer has a different width (teaches a staircase specimen having plural steps/levels (Fig.4a and paras. [0013, 0020]: teaches multiple vertically-stacked levels in a 3D NAND staircase context, and teaches metrology on those steps as distinct measurable features with boundaries used for CD results (“boundaries of Steps” used for CD measurements; “pairs of fine edges… defining left and right boundaries… of each step”, also see fig. 4a, an example of three steps and each step with different width), wherein the system is configured to:
determine one or more properties of one or more of the layers L1 to LN (teaches determining properties of staircase steps/layers via CD measurements based on boundary location, stating “Fine Contour defines the most accurate and precise location of real feature boundaries (e.g. boundaries of Steps) … to be used for CD Measurements,” and “CD Results assume estimation of distance between two fine contours ….”).
However, Kris does not specifically note that the system is configured to obtain different acquisition signals at different landing energies, determine a derivative signal informative of variations of the given acquisition signal for each given acquisition signal data, thereby obtaining a set of derivative signals, and the layer properties are determined using the set of derivative signals.
Villarrubia teaches:
obtain a plurality of different acquisition signals acquired at different landing energies (Page 31 of 39- Section 4.3.3: acquiring/producing results under multiple landing-energy conditions, stating: “Simulations were performed for… four beam landing energies from 500 eV to approximately 4.95 keV (Si) or 5 keV (Cu)….),
determine, for each given acquisition signal data, a derivative signal informative of variations of the given acquisition signal, thereby obtaining a set of derivative signals (Page 33 of 39- Section 4.3.3: metrology measurement values are determined by algorithms applied to images/signals, and specifically teaches that some CD algorithms use slopes “[Some CD algorithms] … are based upon intensity thresholds or slopes ….”). A “derivative signal informative of variations” encompasses a derived representation that emphasizes variation of the acquisition signal versus position, such as slope/gradient-type information. As such, Villarrubia 2011 ’s express teaching of slope-based CD algorithms provides that, for each acquisition signal (at each landing energy), the system determines such variation-emphasizing derived data, thereby obtaining a set of derived variation signals corresponding to the set of acquisition signals),
use the set of derivative signals to determine edges (Pages 31 and 33 of 39- Section 4.3.3: teaches that the slope/derived-variation information is used in CD algorithms to determine edge/measurement outputs, and that edge position defines a measured property, stating: “[Some CD algorithms are] … based upon… slopes …,” and “The position of left and right edges of a feature defines its width”).
Accordingly, modify Kris in view of Villarrubia 2011 would entail that, when a set of derived variation signals (slope/derivative-type signals) is obtained for the plurality of landing-energy acquisition signals, the set of derived variation signals is used within the CD/edge algorithm to determine properties (e.g., edge locations and widths) of one or more of the staircase steps/layers L1 to LN, as recited.
Therefore, it would have been obvious for an ordinary skilled person in the art, before the effective time of filing, to use a set of derivatives/variation signals from the SEM profiles (as taught in Villarrubia 2011) for CD/edge metrology in Kris, because derivative/slope-based processing is a known and predictable way to obtain robust edge/measurement outputs from SEM profile data.
Regarding Claim 13:
Kris in view of Villarrubia 2011 teaches the system of claim 12.
Kris further teaches determine a position of one or more lateral edges of one or more of the layers L1 to LN (CD metrology determines positions/locations of real feature boundaries (lateral edges) via fine contours/fine edges used for CD measurements).
Villarrubia 2011 further teaches compare a first derivative signal obtained at a first landing energy and a second derivative signal obtained at a second landing energy, higher than the first landing energy (teaches running at multiple landing energies, including a higher energy than a lower one: “four beam landing energies from 500 eV to approximately 4.95 keV …” and doing an explicit comparison between signal-profile “shapes” by alignment (“shifting and scaling”) to best agree with a reference model “different shapes of intensity profiles …” and “judged by shifting and scaling the test model to best agree … with a reference model), and
determine a position edge(s) based on a comparison between patterns that appear in the first/second derivative signals and one or more patterns that appear in the first derivative signal (edge position assignment is determined by comparing profile shapes (using “shifting and scaling” to best agree), and “Differences in edge position … judged by shifting and scaling …” “The position of left and right edges of a feature defines its width.”
Accordingly, modify Kris in view of Villarrubia 2011entails that, when the first and second derivative (variation) signals correspond to first and second landing energies (second higher than first), the system determines edge position based on comparing the patterns in those derived signals.
Regarding Claim 19:
Kris teaches a non-transitory computer readable medium comprising instructions that, when executed by one or more processing circuitries, cause the one or more processing circuitries to perform (para. [0011]: teaches “a non-transitory computer readable medium comprising instructions that, when executed by a computer, cause the computer to perform” recited steps):
obtaining a plurality of different acquisition signals of a semiconductor specimen including N vertically stacked layers L1 to LN, with N≥2, wherein each layer has a different width (Fig.4a and paras. [0013, 0020]: teaches multiple vertically-stacked levels in a 3D NAND staircase context, and teaches metrology on those steps as distinct measurable features with boundaries used for CD results (“boundaries of Steps” used for CD measurements; “pairs of fine edges… defining left and right boundaries… of each step”, also see fig. 4a, an example of three steps and each step with different width), and
using the plurality of different acquisition signals to determine one or more properties of one or more of the layers (teaches determining properties of staircase steps/layers via CD measurements based on boundary location, stating: “Fine Contour defines the most accurate and precise location of real feature boundaries (e.g. boundaries of Steps) … to be used for CD Measurements,” and “CD Results assume estimation of distance between two fine contours ….”).
However, Kris does not specifically note that the different acquisition signals are acquired at different landing energies.
Villarrubia 2011 teaches the different acquisition signals are acquired at different landing energies (Page 31 of 39- Section 4.3.3: teaches acquiring/producing results under multiple landing-energy conditions, stating: “Simulations were performed for… four beam landing energies from 500 eV to approximately 4.95 keV (Si) or 5 keV (Cu)….).
Therefore, it would have been obvious for an ordinary skilled person in the art, before the effective time of filing, when implementing Kris’s profile-based edge metrology on a specimen with features at different depth, to acquire different acquisition signals at different landing energy, as taught in Villarrubia 2011, since landing energy is a result-effective imaging parameter and changing landing energy predictably changes interaction volume/penetration and therefore resulting in signal/profile behavior for features at different depth.
Regarding Claim 20:
Kris in view of Villarrubia 2011 teaches the non-transitory computer readable medium of claim 19. Kris further teaches the non-transitory computer readable medium comprising instructions that, when executed by the one or more processing circuitries, cause the one or more processing circuitries to identify patterns in the different acquisition signals to determine edge position of each of the layers L1 to LN (annotated Fig. 4d and paras. [0124, 0130]: teaches the SEM graph has an x-SEM image coordinate as the horizontal axis, and Fig. 4d shows “pairs of fine edges … defining left and right boundaries … of each step,” and these boundaries are used for CD results. Thus, Kris determines/identifies the locations (positions along x) of the step boundaries (lateral edges) in the acquisition signal or a signal derived therefrom).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to JING WANG whose telephone number is (571)272-2504. The examiner can normally be reached M-F 7:30-17:00.
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/JING WANG/Examiner, Art Unit 2881
/WYATT A STOFFA/Primary Examiner, Art Unit 2881