DETAILED ACTION
In the amendment filed on March 23, 2026, claims 1 – 20 are pending. Claims 1, 10, 14 have been amended. Claim 18 has been withdrawn from consideration.
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Analysis
The Examiner notes that support with a reasonable conveyance for the amendments to claim 1 and claim 17 include Figure 3 and paragraphs [0041] – [0042] and paragraph [0054].
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1 – 17, 19 – 20 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Regarding claims 1 and 17:
As a preliminary matter, the Examiner notes that claim 17 is a product-by-process claim. "[E]ven though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process." In re Thorpe, 777 F.2d 695, 698, 227 USPQ 964, 966 (Fed. Cir. 1985).
The Examiner understands the implied structure to be the following: a substrate comprising a feature having a sidewall; and a deposited silicon nitride layer, wherein the silicon nitride comprises silicon and nitrogen, and optionally (as an impurity or minor) hydrogen (from either precursors or hydrogen reactant), chlorine (where the precursor is dimethyldichlorosilane) and a structural property of the deposited silicon nitride due to the claimed provisions of first treatment plasma power and second treatment plasma power. As disclosed in the instant specification, such a structural property includes a continuous difference in wet etch rates between the bottom of the feature having a sidewall, and the top of the feature having a sidewall.
Furthermore, the Examiner notes that the limitation (hereinafter “Limitation A”) “wherein a ratio of a wet etch rate of the silicon nitride layer at a top of the substrate to a wet etch rate of the silicon nitride layer at a bottom of the feature is less than a ratio of a wet etch rate of another silicon nitride layer formed on the feature without the first treatment plasma pulse period.”, and in particular (hereinafter “Limitation B”) “another silicon nitride layer formed on the feature without the first treatment plasma pulse period”. The limitations are negative limitations. While negative limitations are permissible in the claiming of inventions, any negative limitation or exclusionary proviso must have basis in the original disclosure. See In re Johnson, 558 F.2d 1008, 1019, 194 USPQ 187, 196 (CCPA 1977). The mere absence of a positive recitation is not basis for an exclusion.
Claim 1 as presented has been amended to recite Limitation A. The originally filed disclosure does not expressly recite the added claim limitation. The Applicant also has not recited where the newly added claim limitation is supported in the originally filed disclosure.
While there is no in haec verba requirement, newly added claims or claim limitations must be supported in the specification through express, implicit, or inherent disclosure. See MPEP 2163.02 and In re Oda, 443 F.2d 1200, 170 USPQ 268 (CCPA 1971). If a claim is amended to include subject matter, limitations, or terminology not present in the application as filed, involving a departure from, addition to, or deletion from the disclosure of the application as filed, the examiner should conclude that the claimed subject matter is not described in that application. MPEP 2163.02.
The closest recitations of the originally filed disclosure to the subject matter encapsulated in claim 17 include Fig. 3 and paragraphs [0041] – [0042], [0054].
Fig. 3 describes a comparison of a test between an embodiment process according to method timing 100 and timing sequence 200 with the disclosed intermediate treatment step and a comparative process according to method timing 100 and timing sequence 200 without the disclosed intermediate treatment step. The wet etch rates between the embodiment process and the comparative embodiment are then reported.
However as claimed, the comparative process described in Limitation B does not limit the process by which the “another silicon layer” is formed to be the same or otherwise reasonably conveyed by the disclosed method timing 100 and timing sequence 200. The only limitation to Limitation B is the described lack of a first treatment plasma pulse. Limitation B can therefore include the silicon nitride layer formed from any process that does not contain a first treatment plasma pulse period, including the silicon nitride layers formed from purely thermal vapor deposition methods or a physical vapor deposition process. Thus, the new claim introduces New Matter. New or amended claims which introduce elements or limitations that are not supported by the as-filed disclosure violate the written description requirement. See, e.g., In re Lukach, 442 F.2d 967, 169 USPQ 795 (CCPA 1971).
Accordingly, there is no reasonable conveyance to one of ordinary skill in the art that the inventor or joint inventor has possession of the claimed invention at the time the application was filed.
The Examiner notes that the deficiency may be cured by further describing the process by which the “another silicon nitride layer” is formed to better reasonably convey the implied structural characteristics of such a layer.
Claim Rejections - 35 USC § 102/103
The rejection of claim 17 under 35 USC § 102 as anticipated by Ueda et al. US 2019/0333753 A1 (hereinafter “Ueda”) in the previous Office Action is withdrawn due to Applicant amendment.
The rejections of the claims under 35 USC § 103 in the previous Office Action are withdrawn due to Applicant amendment.
Claim(s) 17 is/are rejected under 35 U.S.C. 102(a)(1) and 102(a)(2) as anticipated by or, in the alternative, under 35 U.S.C. 103 as obvious over Ueda et al. US 2019/0333753 A1 (hereinafter “Ueda”).
Regarding claim 17:
Ueda discloses a substrate having trenches with a silicon nitride film deposited thereon, meeting the structural requirements implied by the use of the method disclosed by Ueda (Abstract; Fig. 1) as substantially the same as the claimed structure. Furthermore, Ueda discloses that the that the side-wall etch rate (WER) to the top WER , which includes the middle of a sidewall surface, may be 0.02 to 3.00 ([0024]).
Ueda does not expressly teach that the silicon precursor comprises one or more of the recited species Ueda also does not expressly teach that the volumetric flow ratio of hydrogen reactant to the nitrogen reactant during the overlap period is between 0.0003:1 and about 0.1:1. Finally, Ueda does not expressly teach that the recited ratio of a wet etch rate of the silicon nitride layer at a top of the substrate to the wet etch rate of the silicon nitride layer at the bottom of the feature is less than a wet etch rate of a silicon nitride layer formed on the feature without the recited first treatment plasma pulse period.
However, claim 17 is a product-by-process claim.
With regards to the precursor choice and the volumetric flow ratio of hydrogen reactant to the nitrogen reactant, "[E]ven though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process." In re Thorpe, 777 F.2d 695, 698, 227 USPQ 964, 966 (Fed. Cir. 1985).
With regards to the comparison of wet etch rates:
Ueda teaches or renders obvious the claimed invention above but fails to teach that the recited ratio of the silicon nitride layer formed from the claimed method is less than a ratio of a wet etch rate of another silicon nitride layer formed on the feature without the first treatment plasma pulse period. It is reasonable to presume that such a comparison of wet etch rates is inherent to Ueda. Support for said presumption is found in the result of like or similar silicon nitride material; and that in Ueda, the maximum disclosed ratio of wet etch rate between a top region and the sidewalls is 3.0 ([0024]). Furthermore, Ueda discloses that their disclosed SiN films have greater wet etch resistance and etch rate uniformity compared to the wet etch rate of films that had not been formed with a hydrogen and plasma pretreatment similar to that of the claimed method ([0023]).
This in contrast to the implied wet etch rates of the claimed silicon nitride layer compared to an example silicon nitride formed from a process that differs from the claimed method in that there is no first treatment plasma pulse period treatment, as evidenced in the instant specification in Fig. 3. As exemplified within that figure, the wet etch rate ratios of the non-first plasma treated silicon nitride are 18.7 middle/top and 28.2 middle/top and the wet etch ratios of the example embodiment silicon nitride film is 3.42 middle/top and 5.21 middle/top. The instant specification also states that the inventive silicon nitride films may have wet etch rate middle/top ratios of less than 15 ([0054]).
As the reported wet etch ratio values of Ueda’s disclosure is close to and/or similar to that disclosed within the instant disclosure and Ueda discloses that their silicon nitride films were formed including a plasma treatment having hydrogen and nitrogen, there is preponderance of evidence that supports the presumption that the silicon nitride films disclosed in Ueda would have bottom/top wet etch ratios that are less than silicon nitride films that were formed by a process without a first treatment plasma pulse period. The burden is upon the Applicant to prove otherwise. In re Fitzgerald 205 USPQ 594.
Optionally and additionally, the presently claimed properties would obviously have been present once the Ueda product is provided. Note In re Best, 195 USPQ at 433, footnote 4 (CCPA 1977). Furthermore, it would have been obvious to one of ordinary skill before the effective filing date of the claimed invention to have otherwise modified the silicon nitride films produced by the method disclosed in Ueda to have top/bottom wet etch ratios that are less than those from silicon nitride films without the claimed first plasma pulse period treatment in order to achieve silicon nitride films in features with uniform etch characteristics (Ueda [0023]).
Once the examiner provides a rationale tending to show that the claimed product appears to be the same or similar to that of the prior art, although produced by a different process, the burden shifts to applicant to come forward with evidence establishing a nonobvious difference between the claimed product and the prior art product. In re Marosi, 710 F.2d 799, 803, 218 USPQ 289, 292-33 (Fed. Cir. 1983).
Claim(s) 1 – 6, 8 – 9, 11 – 13, 15 – 17, 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Ueda et al. US 20190333753 A1 (hereinafter “Ueda”) in view of Iijima et al. US 20200075325A1 (hereinafter “Iijima”) and Nguyen et al. US 20140273530 A1 (hereinafter “Nguyen”).
Regarding claims 1, 8, 9, 13, 17, 20:
Ueda is directed to methods of forming silicon nitride films by atomic layer deposition (ALD) (Abstract). Ueda discloses that their methods comprise (Fig. 2, 5):
placing a substrate or workpiece having features with sidewalls in a reaction chamber ([0015], [0035]);
continuously flowing nitrogen gas [N2, nitrogen reactant pulse] in the reaction chamber [meeting claims 7, 8, 9] ([0039], [0042]);
supplying a pulse of silicon precursor, e.g. SiI4 or HSiI3 ([0038]) into the reaction chamber ([0032], [0038], [0044]);
forming a nitrogen plasma in a pulse to convert the silicon precursor into a deposited silicon nitride film, wherein the formation of a nitrogen plasma necessarily involves applying a plasma power ([0039] – [0040], [0077], [0103]);
providing a pulse of hydrogen gas or NH3 [hydrogen reactant, meeting claims 8 and 20] concurrent with the flow of nitrogen [overlapping], wherein a first plasma power is applied during the pulse of hydrogen gas ([0034], [0047] – [0048], [0093]); and
stopping the flow of hydrogen gas while maintaining the flow of nitrogen gas [preventing overlap], wherein a second plasma power is applied to generate a nitrogen-containing plasma without hydrogen in order to further treat the deposited silicon nitride film ([0047] – [0050]).
Ueda does not expressly teach:
that the silicon precursor comprises one or more of a silane, an organosilane selected from trimethylsilane, tetramethylsilane, or dimethyldichlorosilane, or a silazane;
that a volumetric follow ratio of the hydrogen reactant to the nitrogen reactant during the overlap period is between about 0.0003:1 and about 0.1:1; and
a ratio of a wet etch rate of the silicon nitride layer at a top of the substrate to a wet etch rate of the silicon nitride layer at a bottom of the feature is less than a ratio of a wet etch rate of another silicon nitride layer formed on the feature without the first treatment plasma pulse period.
With regards to the silicon precursor comprising one or more of a silane, an organosilane selected from trimethylsilane, tetramethylsilane, or dimethyldichlorosilane, or a silazane:
Iijima is directed to a silicon nitride film forming method (Abstract; [0003] – [0005]). Iijima discloses reacting a deposited silicon precursor with a plasma of reactant gas and hydrogen containing gas (Fig. 2; [0028] – [0031]). Ijima further discloses that alongside silicon precursors only containing iodine and optionally hydrogen ([0020]), suitable precursors for forming silicon nitride films include silazanes having an iodine group, such as SiIH(NH2)2, SiIH(NMeEt)2 ,SiIH(NMe2)2 ([0022]).
Therefore, it would have been obvious to one of ordinary skill before the effective filing date of the claimed invention to have modified the method of Ueda by having an silazane as the silicon precursor because as taught by Iijima, the use of silazanes having iodine groups is known to be suitable for the purpose of being a silicon precursor. The courts have held that the selection of a known material/device/product based for its intended use supports a prima facie case of obviousness. Sinclair & Carroll Co. v. Interchemical Corp., 325 U.S. 327, 65 USPQ 297 (1945), Ryco, Inc. v. Ag-Bag Corp., 857 F.2d 1418, 8 USPQ2d 1323 (Fed. Cir. 1988).
With regards to the volumetric follow ratio of the hydrogen reactant to the nitrogen reactant during the overlap period being between about 0.0003:1 and about 0.1:1:
Nguyen is directed to methods of modifying films comprising SiN with post-deposition treatments using plasmas (Abstract). The use of post deposition plasma modifies the residual stress and the wet etch rate of the treated films and can be fine tuned/modulated (Table 1; [0031], [0034]). In an example, Nguyen discloses a post deposition treatment using a plasma generated from nitrogen gas and ammonia and its effect on the stress and wet etch rate relative to other post deposition treatments (Table 1). Nguyen discloses that combinations of Ar, He, NH3, N2 and H2 modifies the stress and morphology of the treated silicon nitride film by removing hydrogen atoms from the extant silicon atoms and extant hydrogen atoms found in a silicon nitride film before treatment ([0034]). The amount of hydrogen removed from silicon atoms relative to the amount of hydrogen removed from nitrogen atoms within the silicon nitride film, i.e. the SiH/NH selectivity, is controlled by the choice of plasma gases and implicitly their concentrations ([0034], [0100]).
Therefore, it would have been obvious to one of ordinary skill before the effective filing date of the claimed invention to have to have modified the method of in view of Iijima by having a volumetric flow ratio of hydrogen reactant (e.g. hydrogen or ammonia) to nitrogen reactant (e.g. nitrogen) during the overlap period within the claimed range of ratios as a matter of routine experimentation to arrive at desired film stresses and wet etch rates for the SiN film and adjustment of such film stresses as taught by Nguyen. Discovery of optimum value of result effective variable in known process is ordinarily within skill of art. In re Boesch, CCPA 1980, 617 F.2d 272, 205 USPQ215.
With regards to the ratio of a wet etch rate of the silicon nitride layer at a top of the substrate to a wet etch rate of the silicon nitride layer at a bottom of the feature being less than a ratio of a wet etch rate of another silicon nitride layer formed on the feature without the first treatment plasma pulse period.
Ueda in view of Iijima and Nguyen renders obvious the claimed invention above but fails to teach that the recited ratio of the silicon nitride layer formed from the claimed method is less than a ratio of a wet etch rate of another silicon nitride layer formed on the feature without the first treatment plasma pulse period. It is reasonable to presume that such a comparison of wet etch rates is inherent to Ueda in view of Iijima and Nguyen. Support for said presumption is found in the result of like or similar silicon nitride material; and that in Ueda, the maximum disclosed ratio of wet etch rate between a top region and the sidewalls is 3.0 ([0024]). Furthermore, Ueda discloses that their disclosed SiN films have greater wet etch resistance and etch rate uniformity compared to the wet etch rate of films that had not been formed with a hydrogen and plasma pretreatment similar to that of the claimed method ([0023]).
This in contrast to the implied wet etch rates of the claimed silicon nitride layer compared to an example silicon nitride formed from a process that differs from the claimed method in that there is no first treatment plasma pulse period treatment, as evidenced in the instant specification in Fig. 3. As exemplified within that figure, the wet etch rate ratios of the non-first plasma treated silicon nitride are 18.7 middle/top and 28.2 middle/top and the wet etch ratios of the example embodiment silicon nitride film is 3.42 middle/top and 5.21 middle/top. The instant specification also states that the inventive silicon nitride films may have wet etch rate middle/top ratios of less than 15 ([0054]).
As the reported wet etch ratio values of Ueda’s disclosure is close to and/or similar to that disclosed within the instant disclosure and Ueda discloses that their silicon nitride films were formed including a plasma treatment having hydrogen and nitrogen, there is preponderance of evidence that supports the presumption that the silicon nitride films disclosed in Ueda would have bottom/top wet etch ratios that are less than silicon nitride films that were formed by a process without a first treatment plasma pulse period. The burden is upon the Applicant to prove otherwise. In re Fitzgerald 205 USPQ 594.
Optionally and additionally, the presently claimed properties would obviously have been present once the Ueda product is provided. Note In re Best, 195 USPQ at 433, footnote 4 (CCPA 1977). Furthermore, it would have been obvious to one of ordinary skill before the effective filing date of the claimed invention to have otherwise modified the silicon nitride films produced by the method disclosed in Ueda to have top/bottom wet etch ratios that are less than those from silicon nitride films without the claimed first plasma pulse period treatment in order to achieve silicon nitride films in features with uniform etch characteristics (Ueda [0023]), especially in view of Nguyen’s teaching concerning optimization of wet etch rates.
Additionally, regarding claim 17, the resultant structure produced by the method would also have been rendered obvious for the reasons set forth above.
Regarding claims 2, 3:
Ueda does not expressly teach that the deposition plasma power is greater than the second treatment plasma power, especially between 400W and 100W.
However, Ueda does disclose that the power for igniting a hydrogen + nitrogen plasma or a nitrogen without hydrogen plasma may be between 10W to 2000W ([0078] – [0079]). Furthermore, Ueda discloses an embodiment where the first plasma treatment also acts as providing the second reactant for depositing the SiN film (Fig. 5; [0096], [0117]). The plasma power described for deposition and hydrogen pretreatment is disclosed to be higher than the plasma power for the subsequent nitrogen without hydrogen treatment ([0119]). Finally, Ueda discloses that low power nitrogen plasma treatment helps realize the deposition of highly conformal SiN films that are thicker at the bottom and thinner at the top.
Therefore, it would have been obvious to one of ordinary skill before the effective filing date of the claimed invention to have modified the disclosed embodiments of Ueda in view of Iijima to have deposition plasma powers that are greater than the second treatment plasma power because Ueda suggests that the plasma power for deposition may be the same as the plasma power used for the hydrogen+nitrogen plasma treatment and that it is advantageous to have the nitrogen without hydrogen plasma treatment at a lower power than the plasma power used in the creation of an SiN film in order to help form conformal SiN films with desired profiles. With regards to the amount of deposition plasma power, 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); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990); In re Geisler, 116 F.3d 1465, 1469-71, 43 USPQ2d 1362, 1365-66(Fed. Cir. 1997). See MPEP 2144.05
Regarding claim 4:
Ueda discloses that the [second treatment] plasma power applied during the nitrogen-only plasma treatment step may be 300W ([0079]).
Regarding claim 5:
Ueda discloses that the plasma power applied between the hydrogen+nitrogen plasma treatment step and the nitrogen without hydrogen plasma treatment step may be equal (Fig. 3, [0051], [0077] – [0079]), or that the plasma power applied during the hydrogen+nitrogen plasma treatment step (e.g. 550 W) is larger than the plasma power applied during the nitrogen without hydrogen plasma pretreatment step (e.g. 300 W) (Fig. 5, [0051], [0077] – [0079]).
Regarding claim 6:
Ueda discloses that the [second treatment] plasma power applied during the nitrogen without hydrogen plasma treatment step may be 550W ([0079]).
Regarding claim 11:
Ueda discloses that the deposition cycles, including treatments, may be performed at temperatures between 25°C and 700°C ([0081]).
Regarding claim 12:
Ueda discloses that the pressure of the reaction chamber during processing may be maintained from about 0.01 torr to about 50 torr1 ([0082]).
Regarding claim 15:
Ueda discloses depositing the silicon nitride film onto sidewalls of a trench structure (Abstract).
Regarding claim 16:
Ueda discloses that in some embodiments the side-wall wet etch rate (WER) to the top WER , which includes the middle of a sidewall surface, may be 0.01 to 0.03 ([0024]).
Claim(s) 1 – 6, 8 – 9, 11 – 17, 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Ueda in view of Sims et al. US 9214333 B1 (hereinafter “Sims”) and Nguyen.
Regarding claims 1, 2, 3, 4, 5, 6, 8, 9, 11, 12, 13, 14, 15, 16, 17, 20:
The disclosure of Ueda as discussed above in the rejection of claims under 35 USC §103 over Ueda in view of Ijima also apply to the present rejection, mutatis mutandis.
Ueda does not expressly teach:
that the silicon precursor comprises one or more of a silane, an organosilane selected from trimethylsilane, tetramethylsilane, or dimethyldichlorosilane, or a silazane, and in particular (pertinent to claim 14) does not expressly teach that the silicon precursor is one or more of the recited chemical species, e.g. trimethylsilane or trisilylamine;
that a volumetric follow ratio of the hydrogen reactant to the nitrogen reactant during the overlap period is between about 0.0003:1 and about 0.1:1; and
a ratio of a wet etch rate of the silicon nitride layer at a top of the substrate to a wet etch rate of the silicon nitride layer at a bottom of the feature is less than a ratio of a wet etch rate of another silicon nitride layer formed on the feature without the first treatment plasma pulse period.
With regards to the silicon precursor comprising one or more of a silane, an organosilane selected from trimethylsilane, tetramethylsilane, or dimethyldichlorosilane, or a silazane, and in particular (pertinent to claim 14) does not expressly teach that the silicon precursor is one or more of the recited chemical species, e.g. trimethylsilane or trisilylamine;
Sims is directed to methods of depositing a SiN film (Abstract; col 1 lines 5 – 35). Sims discloses that their method is an ALD method comprising a step of providing and adsorbing a film precursor onto a semiconductor substrate in a processing chamber (col 4 lines 4 – 25). The film precursor may be a silane, alkyl silane, siloxane, alkoxysilane, silazane, or halosilanes (col 16 lines 34 – 37). Specific examples include tetrachlorosilane (SiCl4) (col 17 lines 10 –38), silane (SiH4) (col 16 lines 38 – 40), trimethylsilane (HSi(CH3)3) and tetramethylsilane (Si(CH3)4) (col 16 lines 40 – 56), trisilylamine, and tris(dimethylamino)silane (col 17 lines 38 – 67).
Sims discloses that film precursors may be selected based on desired composition properties of the resultant silicon nitride film, including desired physical or electronic properties (col 16 lines 29 – 35).
Therefore, it would have been obvious to one of ordinary skill before the effective filing date of the claimed invention to have modified the method of Ueda by having e.g. tris(dimethylamino)silane as the silicon precursor because as taught by Sims, the use of such silicon precursors are known to be suitable for the purpose of being a silicon precursor. The courts have held that the selection of a known material/device/product based for its intended use supports a prima facie case of obviousness. Sinclair & Carroll Co. v. Interchemical Corp., 325 U.S. 327, 65 USPQ 297 (1945), Ryco, Inc. v. Ag-Bag Corp., 857 F.2d 1418, 8 USPQ2d 1323 (Fed. Cir. 1988).
Furthermore, it would have been additionally obvious to one of ordinary skill before the effective filing date of the claimed invention to have modified the method of Ueda by having e.g. tris(dimethylamino)silane as the silicon precursor because Sims teaches that the selection of such precursors affects the resultant compositional properties of the silicon nitride film produced by practice of a vapor deposition process, and that one of ordinary skill in the art may choose precursors to achieve certain desired properties of the resultant silicon nitride film with a reasonable expectation of success.
Additionally, regarding claim 17, the resultant structure produced by the method would also have been rendered obvious for the reasons set forth above.
With regards to the volumetric follow ratio of the hydrogen reactant to the nitrogen reactant during the overlap period being between about 0.0003:1 and about 0.1:1:
Nguyen is directed to methods of modifying films comprising SiN with post-deposition treatments using plasmas (Abstract). The use of post deposition plasma modifies the residual stress and the wet etch rate of the treated films and can be fine tuned/modulated (Table 1; [0031], [0034]). In an example, Nguyen discloses a post deposition treatment using a plasma generated from nitrogen gas and ammonia and its effect on the stress and wet etch rate relative to other post deposition treatments (Table 1). Nguyen discloses that combinations of Ar, He, NH3, N2 and H2 modifies the stress and morphology of the treated silicon nitride film by removing hydrogen atoms from the extant silicon atoms and extant hydrogen atoms found in a silicon nitride film before treatment ([0034]). The amount of hydrogen removed from silicon atoms relative to the amount of hydrogen removed from nitrogen atoms within the silicon nitride film, i.e. the SiH/NH selectivity, is controlled by the choice of plasma gases and implicitly their concentrations ([0034], [0100]).
Therefore, it would have been obvious to one of ordinary skill before the effective filing date of the claimed invention to have to have modified the method of in view of Iijima by having a volumetric flow ratio of hydrogen reactant (e.g. hydrogen or ammonia) to nitrogen reactant (e.g. nitrogen) during the overlap period within the claimed range of ratios as a matter of routine experimentation to arrive at desired film stresses and wet etch rates for the SiN film and adjustment of such film stresses as taught by Nguyen. Discovery of optimum value of result effective variable in known process is ordinarily within skill of art. In re Boesch, CCPA 1980, 617 F.2d 272, 205 USPQ215.
With regards to the ratio of a wet etch rate of the silicon nitride layer at a top of the substrate to a wet etch rate of the silicon nitride layer at a bottom of the feature being less than a ratio of a wet etch rate of another silicon nitride layer formed on the feature without the first treatment plasma pulse period.
Ueda in view of Iijima and Nguyen renders obvious the claimed invention above but fails to teach that the recited ratio of the silicon nitride layer formed from the claimed method is less than a ratio of a wet etch rate of another silicon nitride layer formed on the feature without the first treatment plasma pulse period. It is reasonable to presume that such a comparison of wet etch rates is inherent to Ueda in view of Iijima and Nguyen. Support for said presumption is found in the result of like or similar silicon nitride material; and that in Ueda, the maximum disclosed ratio of wet etch rate between a top region and the sidewalls is 3.0 ([0024]). Furthermore, Ueda discloses that their disclosed SiN films have greater wet etch resistance and etch rate uniformity compared to the wet etch rate of films that had not been formed with a hydrogen and plasma pretreatment similar to that of the claimed method ([0023]).
This in contrast to the implied wet etch rates of the claimed silicon nitride layer compared to an example silicon nitride formed from a process that differs from the claimed method in that there is no first treatment plasma pulse period treatment, as evidenced in the instant specification in Fig. 3. As exemplified within that figure, the wet etch rate ratios of the non-first plasma treated silicon nitride are 18.7 middle/top and 28.2 middle/top and the wet etch ratios of the example embodiment silicon nitride film is 3.42 middle/top and 5.21 middle/top. The instant specification also states that the inventive silicon nitride films may have wet etch rate middle/top ratios of less than 15 ([0054]).
As the reported wet etch ratio values of Ueda’s disclosure is close to and/or similar to that disclosed within the instant disclosure and Ueda discloses that their silicon nitride films were formed including a plasma treatment having hydrogen and nitrogen, there is preponderance of evidence that supports the presumption that the silicon nitride films disclosed in Ueda would have bottom/top wet etch ratios that are less than silicon nitride films that were formed by a process without a first treatment plasma pulse period. The burden is upon the Applicant to prove otherwise. In re Fitzgerald 205 USPQ 594.
Optionally and additionally, the presently claimed properties would obviously have been present once the Ueda product is provided. Note In re Best, 195 USPQ at 433, footnote 4 (CCPA 1977). Furthermore, it would have been obvious to one of ordinary skill before the effective filing date of the claimed invention to have otherwise modified the silicon nitride films produced by the method disclosed in Ueda to have top/bottom wet etch ratios that are less than those from silicon nitride films without the claimed first plasma pulse period treatment in order to achieve silicon nitride films in features with uniform etch characteristics (Ueda [0023]), especially in view of Nguyen’s teaching concerning optimization of wet etch rates.
Additionally, regarding claim 17, the resultant structure produced by the method would also have been rendered obvious for the reasons set forth above.
Claim(s) 7,19 is/are rejected under 35 U.S.C. 103 as being unpatentable over Ueda in view of Iijima and Nguyen as applied to claims 1 – 6, 8 – 9, 11 – 13, 15 – 17, 20 above, and further in view of Suemori et al. US 10559458 B1 (hereinafter “Suemori”).
Regarding claims 7 and 19:
Ueda in view of Iijima and Nguyen discloses that in general, a generic nitrogen precursor may be used for forming the silicon nitride film and that a pulse of the generic nitrogen precursor may be supplied ([0031]).
Ueda in view of Iijima and Nguyen does not expressly teach that the nitrogen reactant is selected from the recited group and that the hydrogen reactant is selected from the recited group.
Suemori is directed to methods of forming a nitrogen-incorporated silicon oxide film, an oxygen-incorporated silicon nitride film, or an intermediate silicon oxynitride film (Abstract; col 1 line 50 – col 2 line 20). Suemori discloses the use of an oxidizing gas and a nitriding gas which may be supplied together during a step of the plasma-enhanced atomic layer deposition (PEALD) technique (col 8 lines 10 – 20, col 9 lines 45 – 65, col 12 lines 55 – 65, col 14 lines 5 – 45). The oxidizing gas can be a gas containing nitrogen such as N2O, NO and combinations of ammonia or nitrogen gas with oxygen gas. Suemori discloses that an initial SiN film with SiON films improve the adhesion of SiO films onto substrates (col 7 lines 1 – 11). Furthermore, Suemori discloses that for the purpose of forming a silicon nitride film, a gas containing nitrogen can be NH3 and/or N2 + H2 (col 14 lines 5 – 15).
Therefore, it would have been obvious to one of ordinary skill before the effective filing date of the claimed invention to have modified the method of Ueda in view of Iijima by having the nitrogen reactant include/be selected to be either N2O or NO because Suemori suggests that the incorporation of oxidizing gases such as N2O or NO allows for gradient films between SiN to SiO that would improve the adhesion of SiO films onto substrates.
Allowable Subject Matter
Claim 10 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter: the prior art of record does not teach and does not reasonably suggest a method of depositing a silicon nitride layer as recited in claim 10 after incorporation of the subject matter of parent claims 2 and 1. In particular, the prior art of record does not teach and does not reasonably suggest, in the context of the other limitations recited within the instant claim, the combination of:
providing a deposition plasma power to form a plasma within the reaction chamber for a deposition plasma pulse period;
providing a hydrogen reactant to the reaction chamber for a hydrogen reactant pulse period, wherein the nitrogen reactant pulse period and the hydrogen reactant pulse period overlap for an overlap period;
during the overlap period, providing a first treatment plasma power to the reaction chamber for a first treatment plasma pulse period; and
providing a second treatment plasma power to the reaction chamber for a second treatment plasma pulse period, wherein the hydrogen reactant pulse period and the second treatment plasma pulse period do not overlap, wherein the deposition plasma power is greater than the second treatment plasma power, and wherein the hydrogen reactant pulse period begins prior to the first treatment plasma pulse period and ends substantially coincident with an end of the first treatment plasma pulse period and the beginning of the second treatment plasma pulse period;
Response to Arguments
Applicant's arguments filed March 23, 2026 have been fully considered but they are not persuasive.
Applicant’s principal arguments are:
a.) Nguyen does not teach or suggest "… wherein a volumetric flow ratio of the hydrogen reactant to the nitrogen reactant during the overlap period is between about 0.0003:1 and about 0.1:1, and wherein a ratio of a wet etch rate of the silicon nitride layer at a top of the substrate to a wet etch rate of the silicon nitride layer at a bottom of the feature is less than a ratio of a wet etch rate of another silicon nitride layer formed on the feature without the first treatment plasma pulse period, …"
In response to the applicant's arguments, please consider the following comments.
a.) While Nguyen does not teach or suggest Limitation A, Limitation A and the limitation concerning the volumetric flow rate in combination, the limitations are met by the combination of the prior art of record as discussed above.
The test for obviousness is what the teachings of the prior art as a whole would have suggested to one of ordinary skill in the art. See In re Etter, 756 F.2d 852, 859, 225 USPQ 1, 6 (Fed. Cir. 1985) and also In re Keller, 642 F.2d 413, 425, 208 USPQ 871, 881 (CCPA 1981).
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). 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 extension fee 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 date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to JOSE I HERNANDEZ-KENNEY whose telephone number is (571)270-5979. The examiner can normally be reached M-F 6:30-3:30.
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/JOSE I HERNANDEZ-KENNEY/
Primary Examiner
Art Unit 1717
1 The disclosure states “ton”, but the term is a typo of torr, as evidenced by the patent granted from the PG-Pub disclosure. See US 10580645 B2.
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