Ex Parte StrangDownload PDFPatent Trial and Appeal BoardAug 29, 201410469592 (P.T.A.B. Aug. 29, 2014) Copy Citation UNITED STATES PATENT AND TRADEMARK OFFICE _________ BEFORE THE PATENT TRIAL AND APPEAL BOARD __________ Ex parte ERIC J. STRANG __________ Appeal 2013-002323 Application 10/469,592 Technology Center 1700 ___________ Before ADRIENE LEPIANE HANLON, CHUNG K. PAK, and CATHERINE Q. TIMM, Administrative Patent Judges. HANLON, Administrative Patent Judge. DECISION ON APPEAL A. STATEMENT OF THE CASE This is an appeal under 35 U.S.C. § 134 from a final rejection of claims 1-5, 7-16, 20, 21, and 23-27. We have jurisdiction under 35 U.S.C. § 6(b). We REVERSE. The Appellant discloses a plasma processing system and a method of supplying a gas to a plasma processing chamber using a high-pressure pulsed gas flow. Spec. 3, ll. 14-18. The disclosed invention is said to solve Appeal 2013-002323 Application 10/469,592 2 the problem of a lack of gas directivity in known plasma processors.1 See Spec. 2, ll. 23-24. According to the Appellant: [An] object of the present invention [is] to provide a pressure gradient local to a substrate surface. During the short high pressure pulses, the gas flow is temporarily directed normal to the wafer surface under high pressure resulting in an increase in the pressure within a thin layer adjacent to the wafer surface and a more narrow distribution of the gas velocity directivity near the wafer surface. This increases the number of adatoms [(i.e., the chemical species to be deposited on the wafer surface)] at the wafer surface and increases the probability of finding a specific adatom moving in a direction normal to the surface. Spec. 3, ll. 19-25; see also Spec. 5, ll. 24-25. The Appellant discloses that the combination of increasing the number of adatoms at the wafer surface and/or increasing the probability of finding a specific adatom moving in a direction normal to the wafer surface can lead to “improved deposition within high aspect ratio features as well as improved etch process performance.” Spec. 5, ll. 23-27. Claim 1 is representative of the subject matter on appeal and is reproduced below from the Claims Appendix of the Appeal Brief dated May 17, 2012 (“Br.”). The limitation at issue is italicized. 1. A plasma processing system comprising: a plasma processing chamber including a plurality of continuous flow shower-head orifices; 1 The Appellant describes known systems as having “a low mass flow rate (i.e. approximately 500 sccm argon equivalent) suitable for a low-pressure process (i.e. 1 to 50 mTorr)).” Spec. 2, ll. 25-27. Appeal 2013-002323 Application 10/469,592 3 plural pulsed high-pressure injectors interspersed between the plurality of continuous flow shower-head orifices; said plural pulsed high-pressure injectors each being separately connected to a gas feed line; said plurality of continuous flow shower-head orifices being connected to a common volume; at least one continuous flow gas valve configured to provide a first gas to the chamber via the common volume and the continuous flow shower head orifices; at least one pulsed gas valve configured to provide a second gas to the chamber via at least one of the gas feed lines and its respective pressure injector; and a controller coupled to each gas valve and programmed to cause the continuous flow gas valve to provide the first gas in a continuous flow having a flow rate of 100-500 sccm and to cause the pulsed gas valve to provide the second gas in a pulsed flow, each pulse having a flow rate of 1,000-10,000 sccm such that, during each pulse, gas transport adjacent to a surface of a substrate being processed affects at least one of an increase in local number density of adatoms, or an increase in probability of adatoms moving in a direction normal to the surface, to improve processing within high aspect ratio features in the substrate. Claim 12, the other independent claim on appeal, recites a method for supplying a gas to a plasma processing chamber comprising, inter alia, the step of: pulsing a second gas cyclically from pulsed high-pressure injectors at a cyclical flow rate of 1,000-10,000 sccm such that, during each pulse, gas transport adjacent to a surface of a substrate being processed affects at least one of an increase in local number density of adatoms, or an increase in probability of adatoms moving in a direction normal to the surface, to Appeal 2013-002323 Application 10/469,592 4 improve processing within high aspect ratio features in the substrate. Br. 18 (emphasis added). The claims on appeal stand rejected as follows: (1) claims 1, 4, 5, 7, 8, 12-16, 20, 21, and 23-27 under 35 U.S.C. § 103(a) as unpatentable over the combination of Hanazaki2 and Tomoyasu3; (2) claims 2 and 3 under 35 U.S.C. § 103(a) as unpatentable over the combination of Hanazaki, Tomoyasu, and Chang4; and (3) claims 9-11 under 35 U.S.C. § 103(a) as unpatentable over the combination of Hanazaki, Tomoyasu, Koshiishi,5 and Kai.6 B. DISCUSSION A Decision on Appeal was previously entered in the instant Application affirming the decision of the Examiner. See Decision on Appeal dated March 31, 2011 (Appeal 2010-005966); Decision on Rehearing dated August 1, 2011. The Appellant subsequently amended independent claims 1 and 12 to recite that the pulsed flow produces the following result: [D]uring each pulse, gas transport adjacent to a surface of a substrate being processed affects at least one of an increase in local number density of adatoms, or an increase in probability of adatoms moving in a direction normal to the surface, to improve processing within high aspect ratio features in the substrate. Br. 16, 18 (emphasis added). 2 US 6,287,980 B1 issued September 11, 2001. 3 US 5,888,907 issued March 30, 1999. 4 US 4,854,263 issued August 8, 1989. 5 US 5,928,963 issued July 27, 1999. 6 US 5,256,174 issued October 26, 1993. Appeal 2013-002323 Application 10/469,592 5 There is no dispute on this record that neither Hanazaki nor Tomoyasu discloses a flow rate within the claimed range. Nonetheless, the Examiner finds that Hanazaki teaches: improv[ing] processing of high aspect ratio features, such that during each pulse, gas transport adjacent to a surface of the substrate is being processed affects at least one of an increase in local number density of adatoms, or an increase in probability of adatoms moving in a direction normal to the surface, to improve processing within high aspect ratio features in the substrate. Ans. 5, 13.7 The Appellant argues: [T]here is no evidence or technical reasoning on record to link the flow rate variable with the claimed result asserted to be taught by Hanazaki et al. [i.e., improving processing within high aspect ratio features in a substrate]. That is, the Final Action does not provide any analysis for why one skilled in the art would use the flow rate variable to achieve the claimed result. Br. 10-11. The Appellant’s argument is supported by the record. Hanazaki discloses problems associated with wafers having a large diameter. A first problem is that the absolute amount of ions, radicals, or the like reaching the wafer surface varies between the central portion and the peripheral portion of the wafer such that the etching rate, the etching shape, and the like are not uniform across the wafer surface. Hanazaki, col. 3, ll. 33-41. A second problem is RIE lag. Hanazaki, col. 3, ll. 42-51. Hanazaki describes RIE lag as “a phenomenon that the etching rate depends on the pattern size (aspect ratio) and varies with the pattern.” Hanazaki, col. 19, ll. 60-62. 7 Examiner’s Answer dated September 10, 2012. Appeal 2013-002323 Application 10/469,592 6 The Examiner finds that RIE lag is a problem in high aspect ratio processing. Ans. 23. However, the Examiner has not directed us to any portion of Hanazaki disclosing that RIE lag is solved by varying the pulsed flow rate. In the embodiment relied on by the Examiner, Hanazaki discloses that the problems identified above are solved “by pulsatively introducing an etching gas . . . into the buffer chamber and fluctuating the gas pressure in the reaction chamber in the range of about 0.1 mTorr to about 200 mTorr.”8 Hanazaki, col. 4, ll. 14-23 (emphasis added); see also Hanazaki, col. 20, l. 64-col. 21, l. 9. The Examiner also finds that Tomoyasu teaches “optimizing the flow rate in consideration of etching rate, etching selectivity, etched shape and process uniformity.” Ans. 7, 14. However, the Appellant argues that “there is nothing in Tomoyasu et al. to suggest that optimizing or varying flow rates to achieve improved rate, selectivity, shape and uniformity of an etch process will also result in improved directivity and improved processing within high aspect ratio features as recognized by the inventor.” Br. 11. This argument is also supported by the record. Tomoyasu generally discloses that flow rates “are optimized in consideration of parameters, such as etching rate, etching selectivity, etched shaped, and process uniformity.” Tomoyasu, col. 8, ll. 61-64. However, Tomoyasu does not disclose that flow rate, especially a flow rate as high as 1,000-10,000 sccm, improves directivity, and thus, improves processing within high aspect ratio features in a substrate as recited in claims 1 and 12. 8 In this embodiment, Hanazaki discloses that etching gases were introduced into the buffer chamber at mean gas flow rates of 50 sccm, a flow rate significantly lower that the claimed flow rate of 1,000-10,000 sccm. Hanazaki, col. 18, ll. 8-11. Appeal 2013-002323 Application 10/469,592 7 The Examiner does not rely on the remaining prior art of record to cure this deficiency in Tomoyasu. Therefore, the § 103(a) rejections are not sustained. C. DECISION The decision of the Examiner is reversed. REVERSED cdc Copy with citationCopy as parenthetical citation