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 .
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 06/26/2026 has been entered.
Status of the Claims
This is a non-final office action in response to the applicant’s arguments and remarks filed on 06/26/2026. Claims 1-13 and 21-26 are pending in the current office action. Claim 1 has been amended by the applicant. Claim 26 is a new claim. Claims 14-20 are cancelled.
Status of the Rejection
The 35 U.S.C. § 103 rejections for claims 21-24 from the previous office action are substantially maintained and modified only in response to the amendments to the claims.
The 35 U.S.C. § 102 and 103 rejections for claims 1-13 and 25 from the previous office action are withdrawn in view of the Applicant’s amendment.
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 21-24 are rejected under 35 U.S.C. 103 as being unpatentable over Cabansky et al. (WO-2020167765-A1) in view of Yang et al. (US-20210119012-A1), and Schaefer et al. (US-7205226-B1).
Regarding Claim 21, Cabansky teaches a method for selectively etching at least one feature in an oxide region with respect to a nitride region of a stack (Paragraph [0004] method for selectively etching a silicon oxide region relative to a lower oxygen silicon containing region. Paragraph [0013] Figure 2A a SiOCN region (element 208) is a lower oxygen containing region, and contains silicon nitride), comprising:
providing a stack structure with a nitride region and oxide region in a reactor chamber (Paragraph [0013] Figure 2A substrate comprises a silicon oxide region (element 204) and a SiOCN region (element 208) which contains silicon nitride. Paragraph [0018] during processing vapors are purged from a chamber, therefore the process is conducted in a chamber);
selectively depositing a carbon-based mask such that the mask on the nitride region is deposited at a higher rate than on the oxide region, creating a thicker layer on the nitride region than the oxide region (Paragraph [0014] Figure 2B a sacrificial mask (element 216) is selectively deposited on lower oxygen regions (elements 208 and 212) in comparison to the oxide region (element 204), as more deposited on the nitride region (element 208) the deposition rate was higher than for the oxide region); and
performing an etch in-situ on the stack, thereby etching the oxide region to form a feature in the oxide region (Paragraph [0015] the silicon oxide region is selectively etched. Figure 2C shows the substrate after etching, showing a feature etched into the silicon oxide region).
Cabansky fails to teach adding CO gas in the reactor chamber. Cabansky teaches that the carbon-based mask is formed from methane (Paragraph [0014] deposition gas of methane is used).
Schaefer teaches a method of etching a substrate that includes deposition of a protective layer (Column 1 lines 64-67 and Column 2 lines 1-2 method includes deposition of a protective layer). Schaefer teaches a method of depositing a layer that is formed from a gas that can comprise a hydrocarbon (Column 7 lines 18-23 organic material supplied to form a sacrificial carbon-based layer can include a “hydrofluorocarbon” where the integer denoting the number of fluorine atoms is zero). Schaefer teaches that deposition can be optimized with the inclusion of additional gases, such as carbon monoxide, in the deposition process (Column 7 lines 18-23 carbon monoxide can be included in the gases for the deposition process).
It would have been obvious to one of ordinary skill in the art to have modified the method of Cabansky by including carbon monoxide using the gas composition taught by Schaefer for depositing a protective mask layer.
One of ordinary skill in the art would have been motivated to make this modification because Schaefer teaches that including carbon monoxide can allow for optimizing the deposition process (Schaefer Column 7 lines 18-23). Additionally, this modification would have been obvious as it would have been the combination of prior art elements according to known methods to yield predictable results. This modification would have had the predictable result of supplying a suitable gas for use in the deposition process. See MPEP 2143(I)(A).
Cabansky fails to teach that a bias of less than 60W is used.
Yang teaches a method of forming a semiconductor device ([abstract]). Yang teaches that during the process a protection layer containing carbon is formed (Paragraph [0072] the first protection layer is made of carbon-containing material. Paragraph [0071] the first deposition operation forms the first protection layer). Yang teaches that the first deposition process uses a bias power of 0W – 20W (Paragraph [0074] the first deposition operation has a bias power of about 0W – 20W applied).
It would have been obvious to one of ordinary skill to have modified the method of Cabansky by including a bias within the range taught by Yang during the deposition process which is when the CO gas is added to the chamber.
This modification would have been obvious as it would have been the combination of prior art elements according to known methods to yield predictable results. This modification would have had the predictable result of supplying a suitable bias during the deposition process. See MPEP 2143(I)(A).
Regarding Claim 22, modified Cabansky teaches all the limitations of claim 21 as outlined above. Cabansky further teaches wherein the oxide region comprises SiO2 (Paragraph [0004] method for selectively etching a silicon oxide region relative to a lower oxygen silicon containing region.).
Regarding Claim 23, modified Cabansky teaches all the limitations of claim 21 as outlined above. Cabansky further teaches wherein the nitride region comprises SiN (Paragraph [0013] Figure 2A a SiOCN region (element 208) is a lower oxygen containing region, and contains silicon nitride).
Regarding Claim 24, modified Cabansky teaches all the limitations of claim 21 as outlined above.
Cabansky further teaches wherein H2 gas is combined with the CO gas in the reactor chamber (Cabansky [0014] “A deposition gas of 5-50 sccm methane (CH4), 0-200 sccm H2, and 50-500 sccm argon (Ar) is formed into a plasma”). Schaefer also teaches that deposition can be optimized with the inclusion of additional gases, such as hydrogen, in the deposition process (Column 7 lines 18-23 carbon monoxide can be included in the gases for the deposition process).
Allowable Subject Matter
Claims 1-13 and 25-26 are allowed.
The following is an examiner’s statement of reasons for allowance: The prior art does not disclose nor render obvious all of the cumulative limitations of independent claim 1 with particular attention to the limitation “wherein the non-conformality of the carbon-containing mask is due to the geometric shading differential between the surface of the second region and the recessed partial feature”.
The closest prior art of record is considered to be Cabansky. Cabansky teaches a method for selectively etching at least one feature in a first region with respect to a second region of a stack (Paragraph [0004] a method for selectively etching a silicon oxide region with respect to a lower oxygen silicon containing region), comprising: a) selectively etching the first region with respect to the second region to form at least one partial feature in the first region, the at least one partial feature having a depth with respect to a surface of the second region, wherein a top surface of the first region and a top surface of the second region are exposed to the selective etching, wherein before selectively etching there is no mask above the exposed top surface of the first region and the exposed top surface of the second region (Paragraphs [0013-0015] silicon oxide region (element 204), equivalent to the claimed first region, is selectively etched with respect to a silicon oxycarbonitride region (element 208) and a silicon region (element 212), which can be considered equivalent to the second region. Paragraph [0016] Figure 2C the selectivity of the etch is improved by the process, therefore some etching of the SiOCN and Si regions (elements 208 and 212) can occur. Figure 2C shows that the SiOCN and Si regions (elements 208 and 212) are exposed to the etching by the end of the etching process, at which point there is also no mask above the exposed surfaces. The claimed “selective etching” can be considered to occur at the point when both the SiOCN and Si regions are being etched, and not before, and under this interpretation, the claimed “selective etching” would begin when “there is no mask above the exposed top surface of the first region and the exposed top surface of the second region”. All moments of etching prior to that point could be considered a separate etching that is etching the sacrificial mask (element 416) and the Si region, and if there is a selectivity in this etching it is between those elements); b) depositing in-situ a fluorine-free, non-conformal, carbon-containing mask over the first region and the second region, wherein the carbon-containing mask is selectively deposited on the second region at a second thickness with respect to the first region at a first thickness, the second thickness being greater than the first thickness (Paragraph [0014] Figure 2B a sacrificial mask containing carbon is deposited over the silicon oxide and lower oxygen silicon containing regions and selectively deposited on the lower oxygen silicon containing regions (elements 208 and 212) such that the thickness of the mask is greater over these regions. Paragraph [0022] in another embodiment the sacrificial mask is a metal containing layer can be a metal carbide layer, which would contain carbon); and c) further etching in-situ the first region to etch the at least one partial feature and wherein the carbon-containing mask acts as an etch mask for the second region (Paragraph [0013] Figure 1 the process can be repeated such that multiple instances of etching and using the sacrificial mask as an etch mask during the etching can occur in the process).
Cabansky fails to teach wherein the non-conformality of the carbon-containing mask is due to the geometric shading differential between the surface of the second region and the recessed partial feature, teaching instead an alternative means by which non-conformality is achieved.
The claims are therefore considered to be patentably distinguished from the prior art of record. The prior art of record, whether taken alone or in combination, does not disclose nor render obvious the cumulative limitations of claim 1. Claims 2-13 and 25-26 are dependent from or otherwise include the limitations of claim 1 and are allowable for the same reasons as above.
Response to Arguments
Applicant’s arguments, see Remarks Pg. 1-15, filed 06/26/2026, with respect to the rejections against the amended and new claims 1-3 and 25-26 have been fully considered and are persuasive. Therefore, the rejections from the previous office action against these claims have been withdrawn and these claims have been marked allowable as outlined above.
Applicant’s arguments, see Remarks Pg. 2-6, filed 06/26/2026, with respect to the 35 U.S.C. § 103 rejections of claims 21-24 have been fully considered and are not persuasive.
Applicant argues that Schaefer teaches that a carbon-layer deposition process which produces a uniform coating across all exposed surfaces.
Examiner respectfully disagrees with this interpretation of the teachings of Schaefer. Schaefer does not at any point teach that the deposition of the sacrificial layer is uniform, or that the intended goal of the deposition is a uniform layer. Uniformity is never mentioned by Schaefer, with the only teachings that could be interpreted as suggesting uniformity being the depiction of the sacrificial layer in Figure 2 and the mention that in some embodiments the photoresist layer may be removed prior to deposition "Due to the compatibility of the condition required for deposition". Examiner notes that Figure 2 is explicitly described as a "simplified schematic diagram" which supports the interpretation that the elements shown in the figure should not be understood as precise proportions achieved by the process (Also see MPEP 2125(II)). Based on what Schaefer explicitly teaches, and the teachings of Schaefer taken as a whole, Examiner takes the position that Schaefer is not concerned with the uniformity of the sacrificial layer. Instead, examiner takes the position that Schaefer is concerned with ensuring that the sacrificial layer is deposited over each of the layers already on the substrate (the photoresist is removed when this is not possible) so that the sacrificial layer is able to prevent all undesired lateral etching within the opening being formed by the method. Examiner takes the position that the method of Schaefer is relying on the difference of etch rate for the sacrificial layer between horizontal and vertical surfaces to achieve the intended results.
Applicant argues that Schaefer teaches that the purpose of adding CO is to "optimize the uniformity and density of the deposited carbon layer across all surfaces" and therefore Schaefer teaches away from the use of CO in a selective deposition process.
Examiner respectfully disagrees with this interpretation of the teachings of Schaefer. Uniformity is never mentioned by Schaefer and is not taught as goal of including CO. Similarly, the density of the sacrificial layer is also not mentioned by Schaefer, and is not taught as the goal of including CO. Carbon monoxide is taught by Schaefer in two specific contexts. In the first teaching (Column 4 lines 11-15), carbon monoxide is taught as a gas that may be added to a deposition process to "optimize the deposition". Examiner takes the position that one of ordinary skill in the art would understand that the generic teaching that CO can be used to "optimize the deposition" could relate to a variety of end goals for such an optimization (for example: economic or environmental concerns, deposition rate, achieving certain process conditions such as pressure or temperature, or conditions related to plasma formation) and would not understand this generic teaching as relating exclusively or predominantly to uniformity or density, neither of which are mentioned directly. The second teaching (column 7 lines 18-23) teaches that carbon monoxide is an exemplary gas for forming a carbon-based sacrificial layer. Examiner takes the position that these teachings of Schaefer directly support the use of CO as outlined in the rejection above and in no way provide a teaching against the goals of the method of Cabansky.
Applicant argues that the cited prior art fails to teach the specific mechanism of selectivity taught by the instant application and that the cited prior art fails to teach that the use of CO or a low bias promotes selective deposition.
In response to applicant's argument that the references fail to show certain features of the invention, it is noted that the features upon which applicant relies (from 06/26/2026 Remarks Page 4 “CO gas, at low bias and in combination with the distinctive material properties of the nitride and oxide surfaces in the reactor environment, produces a carbon-based mask that deposits preferentially on the nitride region at a much higher rate than on the oxide region... This selectivity is a consequence of the interaction between CO-derived carbon species and the surface chemistry of the respective nitride and oxide regions - silicon nitride surface chemistry is far more reactive toward carbon- containing species than silicon oxide under these specific low-bias plasma conditions”) are not recited in the rejected claims. Although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims. See In re Van Geuns, 988 F.2d 1181, 26 USPQ2d 1057 (Fed. Cir. 1993).
Applicant argues that Yang teaches away from the claimed invention, arguing that Yang teaches a method of uniform deposition, citing Yang at paragraphs [0030] and [0063] and Figure 2B.
Examiner respectfully disagrees with this interpretation of the teachings of Yang. Examiner notes that Yang explicitly teaches that the deposition is not uniform (Figure 2B shows that the deposited layer (element 202a) has two thicknesses (elements T1 and T2), Paragraph [0071] describes that T1 is greater than T2). While Yang does teach that there is a uniform deposition on the horizontal surface ("the portion of the first protection layer 202a covering the top surfaces of the inner spacer 110′ and the metal gate stack 136B has a first thickness T1."), there is no teaching within Yang that this is directly the result of the bias supplied. The only teaching provided by Yang related to the non-uniform deposition taught, notes that the lack of uniformity is the result of the geometry of the substrate and deposition time (Paragraph [0075] "In some embodiments, since the aspect ratio of the recess 142 is high and the operation time of the first deposition operation 201D1 is short, the plasma used for forming the first protection layer 202a is difficult to enter the recess 142. As a result, the first protection layer 202a may merely cover the upper portion of the sidewall of the recess 142. The portion of the first protection layer 202a extending along the sidewall of the recess 142 is thinner than the portion of the first protection layer 202a extending over the metal gate stack 136B."). Examiner takes the position that this further supports the combination outlined in the rejection above - Yang is explicitly teaching that other process conditions result in a non-uniform deposition, with no mention of the bias provided having any effect on this result.
Applicant argues that there is no suggestion that combining CO gas at a low bias would produce the claimed selectivity.
Examiner respectfully disagrees. As outlined in the rejections and arguments above, Cabansky teaches a process that includes a selective deposition and examiner takes the position that one of ordinary skill in the art could have modified the method of Cabansky (by using a deposition gas that comprised CO and a deposition step that comprised a low bias) with a reasonable expectation of success of achieving the intended goals of the method of Cabansky.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to ANDREW KEELAN LAOBAK whose telephone number is (703)756-5447. The examiner can normally be reached Monday - Friday 8:00am - 5:30pm.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Joshua Allen can be reached at 571-270-3176. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/A.K.L./Examiner, Art Unit 1713 /DUY VU N DEO/Primary Examiner, Art Unit 1713
Prosecution Insights