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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.
Applicant's submission filed on 3/25/26 has been entered. Claims 1-3, 6-8, 11-13, 16-17, and 19-20 are currently pending examination.
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.
Claim(s) 1-3, 6-8, 11, 13, 16-17, and 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Liu et. al. (US 2020/0105523; hereafter Liu) in view of Zhou et al (US2020/0350160; hereafter Zhou), and Shih et al (US 2008/0203528; hereafter Shih).
Claims 1 and 6: Liu teaches a method of depositing a compressive nitride film on a bowed semiconductor substrate, (see, for example, abstract, [0033], [0038]) the method comprising:
providing a bowed semiconductor substrate having one or more regions of tensile stress and one or more regions of compressive stress (see, for example, abstract, [0008], [0030]);
and depositing, by plasma-enhanced chemical vapor deposition (PECVD), at a deposition temperature of between about 300oC and 550oC, a compressive nitride film on a backside of the bowed semiconductor substrate, wherein the compressive nitride film has a compressive film stress (see, for example, abstract, [0008], [0030], [0033], [0038], [0055])
wherein the PECVD is performed to deposit the compressive nitride film on the backside of the bowed semiconductor substrate using a LFRF power and a HFRF power (See, for example, abstract, [0016-0017], Table 1, [0057], [0071-77]).
Liu teaches the method above, but is silent as to the value of stress shift of its compressive nitride film, therefore it does not explicitly teach a shift within the claimed range. Zhou teaches a method of depositing a compressive nitride film onto the backside surface of a bowed semiconductor substrate, (see, for example, abstract, [0003-4], [0021][0028-29]). Zhou further teaches wherein retention of stress aids in proper bow compensation, and wherein stress retention at temperatures at and in excess of 850oC, such as 950C are preferably on the order of about 70% (see, for example, [0029] and [0036-38]). Therefore it would have been obvious to one of ordinary skill in the art at the time before the effective filing date of the claimed invention to have incorporated a stress shift of about 30% when the compressive film is exposed to a temperature greater than 850oC since such an order is known in the art to be desirable for adequate mitigation design, since maximizing retention would predictably reduce deviation from target stress compensation goals, and since when a primary reference is silent as to a certain detail, one of ordinary skill would be motivated to consult a secondary reference which satisfies the deficiencies of the primary reference. Although no singular exemplary embodiment is provided at such temperatures and exact exemplary retention values, it would have been obvious to one of ordinary skill in the art at the time before the effective filing date of the claimed invention to have incorporated retention values within the claimed range since 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, 191USPQ 90 (CCPA 1976), discovery of an optimum value of a result effective variable in a known process is ordinarily within the skill of the art. In re Boesch, 617 F.2d 272, 276 (CCPA 1980), and since a reasonable expectation of success exists from choosing the specific taught species from explicitly taught lists. Further when the species is clearly named, the species claim is anticipated (rendered obvious) no matter how many other species are additionally named. Ex parte A 17 USPQ2d 1716 (Bd. Pat. App. & Inter. 1990).
Liu further teaches wherein the compressive film stress can be tailorable to the magnitude of the bow of substrate to adequately mitigate it (See, for example, abstract, [0044], [0065]) and Zhou further teaches corrective compressive stress on the order of 1.5 GPa silicon nitride films are suitable for addressing conventional degrees of bowing (See, for example, [0021], [0029]). Therefore it would have been obvious to one of ordinary skill in the art at the time before the effective filing date of the claimed invention to have incorporated a compressive nitride possessing a compressive film stress of about 1.5 GPa since such a magnitude would perform predictably as a backside silicon nitride film to correct bowing issues in the art, and since when a primary reference is silent as to a certain detail, one of ordinary skill would be motivated to consult a secondary reference which satisfies the deficiencies of the primary reference.
Liu further teaches wherein the dual frequency process conditions influence that stress of the deposited film (See, for example, [0057]), but does not explicitly teach wherein the LFRF power is equal to or less than about 20% of a total RF power applied between the LFRF and the HFRF power. Shih teaches a method of depositing PECVD compressive silicon nitride films (See, for example, abstract, [0032-0034]). Shih further teaches wherein such silicon nitride films with compressive stress of greater than 1 GPa, and further nearly 4.5 GPa can be achieved with LFRF power of 100-500W, further 100 W and HFRF power between 630 and 770, further 700 W (LFRF/(LFRF+HFRF) of about 11.5 % to 44%, further with an exemplary ratio of ~12.5% (See, for example, [0033-34]). Therefore it would have been obvious to one of ordinary skill in the art at the time before the effective filing date of the claimed invention to have incorporated an LFRF and HFRF power wherein the LFRF power is equal to or less than about 11.5 % to 44%, of a total RF power applied, further 12.5% since such conditions provide predictable power conditions for achieving compressive stresses in silicon nitride layers on the level desired (~1.5 GPa compressive) and which would perform predictably as a backside silicon nitride film to correct bowing issues in the art. Additionally / optionally with respect to the range of 11.5% to 44% LFRF: total power, although such a range is not explicitly less than about 20% as claimed, it would have been obvious to one of ordinary skill in the art at the time before the effective filing date of the claimed invention to have incorporated a ratio within the claimed range since 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, 191USPQ 90 (CCPA 1976)
As the above combination has formed a compressive nitride film by a method involving deposition temperature and LFRF/ HFRF powers, the resulting film stress would intrinsically have been based, at least in part, on said temperatures and powers.
Claim 2: Liu further teaches wherein the compressive nitride film is undoped silicon nitride, oxygen-doped silicon nitride, or carbon-doped silicon nitride (see, for example, [0018], [0046], [0049]).
Claim 3: Liu further teaches wherein the compressive nitride film is undoped silicon nitride (see, for example, [0018], [0046], [0049]).
Claim 7: Liu further teaches depositing a tensile nitride film on the backside of the bowed semiconductor substrate, wherein the tensile nitride film is deposited in the one or more regions of compressive stress and the compressive nitride film is deposited in the one or more regions of tensile stress to mitigate bowing on a frontside of the bowed semiconductor substrate. (See, for example, abstract, [0016-0017] [0071-77]).
Claim 8: Liu further teaches wherein depositing the compressive nitride film by PECVD comprises: exposing the backside of the bowed semiconductor substrate to a silicon-containing precursor and a nitrogen-containing reactant; and exposing the backside of the bowed semiconductor substrate to plasma to drive a reaction between the silicon-containing precursor and the nitrogen-containing reactant to deposit the compressive nitride film (See, for example, abstract, [0016-0017] [0071-77]).
Claim 11: Liu further teaches wherein the process conditions including flow rates influence that stress of the deposited film (See, for example, [0057], [0061]). Liu further teaches wherein the silicon containing precursor includes silane (See, for example, [0058]); and wherein a flow rate of silane is from 1400-2600 sccm, the flow rate of NH3 is from 8400-15600 and the flow rate of N2 is from 8400-15600 sccm, and flow rate of N2 from top of substrate is from 2800-5200 (see, for example, Table 1; wherein by calculation, the ratio of silane to the total gas flow in the PECVD ranges from 3.7 to 11.7 %). Although such a range is not explicitly flow rate of silane equal to or less than about 5% by volume of a total gas mixture in PECVD; it would have been obvious to one of ordinary skill in the art at the time before the effective filing date of the claimed invention to have incorporated such a value within the claimed range since 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, 191USPQ 90 (CCPA 1976), and / or discovery of an optimum value of a result effective variable in a known process is ordinarily within the skill of the art. In re Boesch, 617 F.2d 272, 276 (CCPA 1980).
Claims 13 and 16: refer to the rejections of claims 1-3, 6-8, and 11 over Liu in view of Zhou and Shih above.
Claim 17: Liu in view of Zhou and Shih teaches the method of claim 13 above, and Liu further teaches wherein the thickness of the compensation layer is influenced by the magnitude of the bow correction desired (See, for example, [0065]). Zhou similarly teaches wherein backside thickness can be tailored to compensate respective bowing, and further teaches wherein thickness on the order of 0.1 to 1 micron are known in the art to adequately correct varying degrees of bowing (See, for example, [0029] [0040]). Therefore it would have been obvious to one of ordinary skill in the art at the time before the effective filing date of the claimed invention to have incorporated a compressive nitride thickness on the order of 0.1 to 1 micron since such thicknesses achieve the predictable result of correcting degrees of bowing conventional in the art, and since discovery of an optimum value of a result effective variable in a known process is ordinarily within the skill of the art. In re Boesch, 617 F.2d 272, 276 (CCPA 1980). Although 0.1 to 1 micron is not explicitly less than 300 nm, it would have been obvious to one of ordinary skill in the art at the time before the effective filing date of the claimed invention to have incorporated a thickness within the claimed range since 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, 191USPQ 90 (CCPA 1976).
Claim 20: Liu further teaches the bowed semiconductor substrate has one or more tensile regions, wherein the silicon nitride film mitigates bowing in the one or more tensile regions of the bowed semiconductor substrate (see, for example, Abstract, [0003], [0017], [0033], [0047] [0056]).
Claim(s) 12 and 19 is/are rejected under 35 U.S.C. 103 as being unpatentable over Liu in view of Zhou, and Shih as applied to claim 1 and 13 above, and further in view of Vorsa et al (US 2010/0120262; hereafter Vorsa).
Claims 12 and 19: Liu in view of Zhou, and Shih teaches the methods of claims 1 and 13 including embodiments of preparing compressive nitride coatings (Above) Liu further teaches wherein the intended coating is silicon nitride, further undoped; so intrinsically the number of Si-N bonds within an undoped silicon nitride layer would outnumber Si-H bonds (See, for example, [0018], [0046], [0049]). But Liu is silent as to the relative amounts of N-H, Si-H, and Si-N bonds present in the compressive nitride film, so it does not explicitly teach wherein a number of N—H bonds is greater than a number of Si—H bonds in the compressive nitride film. Vorsa teaches a method of PECVD deposition of compressive silicon nitride coatings (see, for example, abstract). Vorsa further teaches wherein a higher ratio of N-H bonds to Si-H bonds correlates to enhanced compressive stress (See, for example, Fig 4), and preferably recommends a ratio of 25 to 85 (See, for example, [0026]). Therefore it would have been obvious to one of ordinary skill in the art at the time before the effective filing date of the claimed invention to have incorporated a number of N—H bonds is greater than a number of Si—H bonds in the compressive nitride film since such a higher number of N-H bonds would predictably enhance the obtainable compressive stress. Vorsa additionally evidences / demonstrates that Si-N bonds in silicon nitride are greater than the number of Si-H bonds (see, for example, Fig 3).
Response to Arguments
Applicant’s 3/19/26 amendments entered via 3/25/26 RCE have been fully considered and are persuasive with respect to the rejection(s) of claim(s) over Liu in view of Zhou, Fox and Raoux. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of Liu in view of Zhou and Shih.
In response to applicant's arguments against the references individually (Zhou uses PVD, not PECVD), one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986). The rejection is over a combination of references, not Zhou alone. Zhou is not relied upon for PVD, rather its reliance is upon its teaching that a stress shift of about 30% is desirable in art for adequate mitigation design to predictably reduce deviation from target stress compensation goals, and the desirability of a compressive film stress of about 1.5 GPa since such a magnitude would perform predictably as a backside silicon nitride film to correct bowing issues in the art. Primary reference Liu (and now further Shih) have been relied upon for deposition via PECVD, thus such teaching is not similarly requisite to be attributed to Zhou.
Conclusion
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/NATHAN H EMPIE/Primary Examiner, Art Unit 1712
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