DETAILED ACTION
Claims 1-5 are pending before the Office for review.
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 .
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1-5 are rejected under 35 U.S.C. 103 as being unpatentable over NAJAFI et al (U.S. Patent 6,884,732) in view of JOSEPH et al (U.S Patent Application Publication 2020/0135898) and VORA et al (U.S. Patent Application Publication 2020/0271850).
With regards to claims 1 and 4, Najafi discloses a method of deep etching a substrate, the method comprising: disposing a hard mask layer (24) on the substrate (22) (Figure 4a); performing a deep etch of the structure using a single etch recipe that etches both the hard mask and the substrate wherein the deep etch provides a multilevel pattern into the substrate (Figure 2a) (Col. 4 lines 5-25).
Najafi does not explicitly disclose etching a first multi-level pattern into the hard mask layer using two or more iterations of photoresist patterning followed by etching to provide etched features in the hard mask layer having two or more depths, wherein the single etch recipe has an etch rate in the substrate at least 10x its etch rate and at least 100X in the hard mask layer; wherein the deep etch is performed for a time sufficient to at least partially etch through the hard mask layer, thereby deep-etching a second multi-level pattern into the substrate that corresponds to the first multi- level pattern, but has magnified vertical feature dimensions.
Vora discloses a metho of etching a variable etch depths in a substrate 710 using a masking layer comprising a hard mask and photoresist layer (734, 720) wherein the combination of photoresist and hardmask provide a pattern of varying heights and wherein the substrate is etched in a single etch step to form a variety of trenches of variable depths (Figure 7E) (Paragraphs [0095]-[0097]) Joseph discloses a method of etching a high aspect ratio etching in a silicon substrate using a hardmask wherein the one or more hardmask can exhibit a selectivity of 10 during the dry etch process and wherein the etching is done with the hardmask to etch the pattern into the substrate (Paragraphs[0025], [0027]-[0033]). Therefore Najafi as modified by Vora and Joseph renders obvious etching a first multi-level pattern into the hard mask layer using two or more iterations of photoresist patterning followed by etching to provide etched features in the hard mask layer having two or more depths, wherein the single etch recipe has an etch rate in the substrate at least 10x its etch rate in the hard mask layer; wherein the deep etch is performed for a time sufficient to at least partially etch through the hard mask layer, thereby deep-etching a second multi-level pattern into the substrate that corresponds to the first multi- level pattern, but has magnified vertical feature dimensions. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976). MPEP 2144.05(I) In addition it would have been prima facie obvious to optimize the etch rate of the substrate to amounts including Applicant’s claimed amount of at least 100x its etch rate in the hardmask in order to etch the desired depth while the hardmask is thinning as taught by the modified teachings of Najafi (Joseph Paragraph [0033], MPEP 2144.05(II)(A))
It would have been prima facie obvious to one of ordinary skill in the art prior to the effective filing date of the invention to modify the method of Najafi to include the multilevel pattern as rendered obvious by Vora because one of ordinary skill in the art prior to the effective filing date of the invention would have had a reasonable expectation of predictably achieving the desired etching using the multilevel pattern as rendered obvious by Vora. MPEP 2143
It would have been prima facie obvious to one of ordinary skill in the art prior to the effective filing date of the invention to modify the method of Najafi to include the etch rate as rendered obvious by Joseph because one of ordinary skill in the art prior to the effective filing date of the invention would have had a reasonable expectation of predictably achieving the desired etching using the etch rate as rendered obvious by Joseph. MPEP 2143
With regards to claim 2, the modified teachings of Najafi renders obvious wherein the hard mask layer comprises silicon dioxide (Joseph Paragraph [0029]) and wherein the substrate comprises silicon (Najafi Col. 4 lines 8-25, Joseph Paragraph [0027]).
With regards to claim 3, the modified teachings of Najafi renders obvious wherein the thickness of the hard mask layer is 5nm 0 250nm (Joseph paragraph [0029]) which render obvious Applicant’s claimed amount of wherein a thickness of the hard mask layer is 3 microns or less. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976). MPEP 2144.05(I)
With regards to claim 5, the modified teachings of Najafi renders obvious wherein the second multi-level pattern includes features having an aspect ratio of greater than 2 (Najafi Col. 2 lines 18-22 Joseph Paragraph [0025] discloses a high aspect ratio) which render obvious Applicant’s claimed height/width aspect ratio of 10 or more. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976). MPEP 2144.05(I)
Response to Arguments
Applicant's arguments filed August 12, 2025 have been fully considered but they are not persuasive.
Applicant argues on pages 4-6 of Applicant’s response that the cited prior art fails to teach or render obvious “"etching a first multi-level pattern into the hard mask layer using two or more iterations of photoresist patterning followed by etching to provide etched features in the hard mask layer having two or more depths", and "deep-etching a second multi-level pattern into the substrate that corresponds to the first multi-level pattern, but has magnified vertical feature dimensions.” Applicant argues that “an art worker given the Najafi and Vora references will not arrive at these claim elements without impermissible hindsight reconstruction.” It is Applicant’s position that one of ordinary skill in the art would not be motivate to look at Vora in view of Najafi as Najafi already provides a muti level etch method. In addition, it would seem to be an unreasonably difficult process to calibrate, and gray scale lithography as in Vora is already well known to be a challenging process to calibrate.
Therefore it Is Applicant’s position that claim 1 is allowable. As to the dependent claims, they are allowable based off their dependency. This is found unpersuasive.
It is the Examiner’s position that the cited prior art renders obvious Applicant’s claimed invention. It is the Examiner’s position that the cited prior art renders obvious “"etching a first multi-level pattern into the hard mask layer using two or more iterations of photoresist patterning followed by etching to provide etched features in the hard mask layer having two or more depths", and "deep-etching a second multi-level pattern into the substrate that corresponds to the first multi-level pattern, but has magnified vertical feature dimensions.”
Najafi discloses performing a deep etch of the structure using a single etch recipe that etches both the hard mask and the substrate wherein the deep etch provides a multilevel pattern into the substrate (Figure 2a) (Col. 4 lines 5-25). Vora discloses a metho of etching a variable etch depths in a substrate 710 using a masking layer comprising a hard mask and photoresist layer (734, 720) wherein the combination of photoresist and hardmask provide a pattern of varying heights and wherein the substrate is etched in a single etch step to form a variety of trenches of variable depths (Figure 7E) (Paragraphs [0095]-[0097])
In response to applicant's argument that the examiner's conclusion of obviousness is based upon improper hindsight reasoning, it must be recognized that any judgment on obviousness is in a sense necessarily a reconstruction based upon hindsight reasoning. But so long as it takes into account only knowledge which was within the level of ordinary skill at the time the claimed invention was made, and does not include knowledge gleaned only from the applicant's disclosure, such a reconstruction is proper. See In re McLaughlin, 443 F.2d 1392, 170 USPQ 209 (CCPA 1971).
It is the Examiner position that one of ordinary skill would recognize that both methods are suitable for achieving the desired single step etching for etching a multilevel pattern. In addition it is prima facie obvious to combine known equivalents know for the same purpose (MPEP 2144.06) Therefore it is the Examiner’s position that one of ordinary skill in the art would be motivated to look at both Najafi and Vora in order to perform the deep etching. The Examiner maintains the rejection of independent claim 1. As to the dependent claims they remain rejected as no separate arguments have been provided.
Conclusion
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/STEPHANIE P DUCLAIR/Primary Examiner, Art Unit 1713