METHOD OF PLASMA ETCHING

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 . Election/Restrictions Applicant’s election without traverse of Group I, claims 1-18, in the reply filed on 7/28/2026 is acknowledged. 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. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. Claim(s) 1-10 and 12-18 is/are rejected under 35 U.S.C. 103 as being unpatentable over Wood et al (US 2023/0197457; herein after wood’457) in view of Wood et al (US 2023/0170188; herein after Wood’188) and further in view of Demmin et al (US 6,635,185). Regarding claims 1-6, wood’457 discloses a method of plasma etching an additive-containing aluminium nitride film comprising plasma etching an additive-containing aluminium nitride film containing an additive element selected from Sc, Y or Er through a mask with a plasma formed in a gaseous atmosphere [0011]; wherein the gaseous atmosphere can comprise an etch precursor, optionally in combination with one or more of an inert gas and H.sub.2 [0024]; The gaseous composition can comprise a chlorine containing etch precursor. The gaseous composition can comprise the chlorine containing etch precursor and a noble gas. The ratio of the flow rate in sccm of the chlorine containing etch precursor to the combined flow rates in sccm of the chlorine containing etch precursor and Noble gas in the gaseous atmosphere can be adjusted between values which are in the range 40 to 100% [0026[; and the chlorine containing etch precursor can be Cl.sub.2. The noble gas can be Ar [0027].; aforesaid noble gas (argon) reads on the claimed “inert diluent gas”. Unlike the instant invention, wood’457 fails to disclose the gaseous atmosphere comprises BCl3. However, in the same field of endeavor, Wood’188 discloses [0007] a method of plasma etching an additive-containing aluminium nitride film, the additive-containing aluminium nitride film containing an additive element selected from scandium (Sc), yttrium (Y) or erbium (Er), the process comprising: [0008] placing a workpiece upon a platen within a plasma chamber, the workpiece comprising a substrate having an additive-containing aluminium nitride film deposited thereon and a mask disposed upon the additive-containing aluminium nitride film which defines at least one trench; [0009] introducing a first etching gas into the chamber with a first flow rate; [0010] introducing a second etching gas into the chamber with a second flow rate; and [0011] establishing a plasma within the chamber to etch the additive-containing aluminium nitride film exposed within the trench; [0012] wherein the first etching gas comprises boron trichloride (BCl3) and the second etching gas comprises chlorine, and [0013] wherein a ratio of the first flow rate to the second flow rate is greater than or equal to 1:1; Wood et al disclose [0007] a method of plasma etching an additive-containing aluminium nitride film, the additive-containing aluminium nitride film containing an additive element selected from scandium (Sc), yttrium (Y) or erbium (Er), the process comprising: [0008] placing a workpiece upon a platen within a plasma chamber, the workpiece comprising a substrate having an additive-containing aluminium nitride film deposited thereon and a mask disposed upon the additive-containing aluminium nitride film which defines at least one trench; [0009] introducing a first etching gas into the chamber with a first flow rate [0010] introducing a second etching gas into the chamber with a second flow rate; establishing a plasma within the chamber to etch the additive-containing aluminium nitride film exposed within the trench [0012], when etching additive-containing aluminium nitride films to permit steeper sidewall profiles to be generated. Additionally, flow rate ratios of BCl.sub.3 to Cl.sub.2 ≥1:1 can increase the additive-containing aluminium nitride film selectivity to bottom electrodes, reducing the underlayer loss when etching to one of these underlayer electrode films [0014]. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to employ Wood’188's teaching of introducing BCl3 during etching the film into the teaching of Wood’457 for steeper etched profile with selectivity as suggested by Wood’188 [0014]. The modified Wood’457 teaching above and Wood’457 also disclose the composition of the gaseous atmosphere can be adjusted to tune one or more of the etch rate, etch selectivity, profile and redeposition formation. The amount of the etch precursor can be adjusted. The flow rate in sccm of the etch precursor can be adjusted [0025]; but may not specifically disclose the claimed ratio of the flow rate of inert diluent gas to BCl3 and the ratio of the BCl3 to the H2. However, it has been held that, generally, differences in concentration or flow rates will not support the patentability of subject matter encompassed by the prior art in the absence of evidence indicating that said flowrate ratio is critical. See MPEP 2144.05.II.A. Additionally, Demmin et al disclose that (at col.7, lines 15-25) PNG media_image1.png 182 386 media_image1.png Greyscale Therefore, it would have been obvious to one with ordinary skill in the art to optimize the flow rates of the etching components in the method of Wood et al because Demmin teaches that changing the parameters according to the material being etched appears to reflect a result-effective variable which can be optimized. See MPEP 2144.05 IIB. Regarding claim 7, Wood’457 discloses the frequencies supplied to the RF antenna 314 and to the substrate support 320 were both 13.56 MHz. However, frequencies over the range 2-13.56 MHz could be used for the RF antenna 314 while frequencies from 380 kHz-13.56 MHz could be used for the RF bias applied to the substrate support [0050]. Regarding claims 8-10, modified Wood’457 discloses above for the claim 1, which also applies for the claim 8 that is similar in nature except the workpiece comprises a substrate having a metal film disposed in the plasma chamber, wherein the additive-containing aluminum nitride film deposited on the metal film. Wood’457 also discloses that a composite substrate may comprise an underlayer having an upper layer formed thereon, wherein the additive-containing aluminium nitride film is disposed on the upper layer. The substrate can comprise a semiconductor material, such as silicon. The substrate can comprise a metallic material. The metallic material can be present as a metallic upper layer on an underlayer. The metallic material can be molybdenum, platinum or tungsten [0029]. Wood’457 fails to disclose performing a first plasma etching with BCl3, Cl2 and an inert diluent gas and a second plasma etching by introducing a BCl3, H2 and an inert diluent gas. However, in the same field of endeavor, Wood’188 discloses [0009] introducing a first etching gas into the chamber with a first flow rate; [0010] introducing a second etching gas into the chamber with a second flow rate; and [0011] establishing a plasma within the chamber to etch the additive-containing aluminium nitride film exposed within the trench; [0012] wherein the first etching gas comprises boron trichloride (BCl3) and the second etching gas comprises chlorine (Cl2), and [0013] wherein a ratio of the first flow rate to the second flow rate is greater than or equal to 1:1. Wood et al disclose that the method further comprises introducing a third etching gas, such as argon, into the chamber. The third etching gas is introduced into the chamber with a third flow rate, a ratio of the first flow rate to the third flow rate being greater than 2:1 [0015]; and the first flow rate comprises substantially 60 sccm and the second flow rate comprises substantially 40 sccm; and the third etching gas is introduced into the chamber with a third flow rate within the range 20-25 sccm [0017],[0040]; and aforesaid flow rates appears to be overlapping or encompasses the claimed ranges and overlapping ranges are prima facie obvious, MPEP 2144.05. Additionally, the performance of two steps simultaneously, which have previously been performed in sequence was held to have been obvious. In re Tatincloux 108 USPQ 125 (CCPA 1955). Regarding claim 12, Wood’457 disclose above that the noble gas can be Ar [0027].; aforesaid noble gas (argon) reads on the claimed “inert diluent gas”. Regarding claim 13, Wood’457 discloses above that the metal film comprises molybdenum [0029]. Regarding claim 14, Wood’457 discloses that the mask is a photoresist mask [0016]. Regarding claim 15, Wood’457 discloses that the plasma generation device can be an ICP (inductively coupled plasma) [0038]. Regarding claim 16, Wood’457 discloses that the gas pressure can be in the range 0.5 to 25 mTorr, optionally 1 to 15 mTorr, during the plasma etching [0018] Regarding claim 17, Wood’457 discloses that the substrate can comprise a semiconductor material, such as silicon [0029]. Regarding claim 18, Wood’457 discloses that the additive-containing aluminium nitride film comprises aluminium scandium nitride film (AlScN) [0009]; and aforesaid AlScN film encompasses the claimed formula. Allowable Subject Matter Claim 11 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 fails to teach or renders obvious to a process, including the step of Cl2 gas is not introduced into the plasma chamber during the second etching as the context of the claim 11. Conclusion The prior art made of record, listed in the PTO-892 and not relied upon is considered pertinent to applicant's disclosure. Xu et al (US 2012/0003827) disclose a plasma etching of the AlN or TaN barrier metal layer, the TiN metal gate and the high-K gate dielectric film is performed by using BCl.sub.3 and Cl.sub.2 as main etching gases with one or both of O.sub.2 and Ar added as supplementary etching gases to improve etching characteristics [0012]-[0013]. Bauer (US 9,484,216) discloses an etching process of semiconductor devices, such aluminum nitride; wherein the methods herein allow for devices having improved etch profiles, such that nearly vertical sidewalls can be obtained. In some examples, the method employs a dry etch step with a primary etchant gas that omits BCl.sub.3, a common additive (abstract). Any inquiry concerning this communication or earlier communications from the examiner should be directed to SHAMIM AHMED whose telephone number is (571)272-1457. The examiner can normally be reached M-TH (8-5:30pm). 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. SHAMIM AHMED Primary Examiner Art Unit 1713 /SHAMIM AHMED/ Primary Examiner, Art Unit 1713