Ex Parte Teo et alDownload PDFPatent Trial and Appeal BoardMay 6, 201411333399 (P.T.A.B. May. 6, 2014) Copy Citation UNITED STATES PATENT AND TRADEMARK OFFICE ____________ BEFORE THE PATENT TRIAL AND APPEAL BOARD ____________ Ex parte JOCELYN WEI-YEE TEO, CHI-CHUN CHEN, and SHIH-CHANG CHEN ____________ Appeal 2012-000687 Application 11/333,399 Technology Center 2800 ___________ Before ADRIENE LEPIANE HANLON, CATHERINE Q. TIMM and JAMES C. HOUSEL, Administrative Patent Judges. HOUSEL, Administrative Patent Judge. DECISION ON APPEAL Appeal 2012-000687 Application 11/333,399 2 Appellants1 seek our review under 35 U.S.C. § 134 of the Examiner’s decision finally rejecting claims 9-19, 21, 22, 25-29, and 31-33. We have jurisdiction over the appeal under 35 U.S.C. § 6(b). We AFFIRM-IN-PART.2 STATEMENT OF THE CASE The invention relates to a method of forming metal oxide semiconductor (MOS) devices using hydrogen annealing. Spec. ¶ [0007]. Appellants disclose, in reference to Figure 7A reproduced below, due to hydrogen annealing, surface 40 in the active region 100 has a convex surface or a substantially rounded surface. Id. at ¶ [0024]. According to Appellants, the curvature “introduces beneficial strain to the channel region of the MOS 1 Appellants identify the Real Party in Interest in this appeal as Taiwan Semiconductor Manufacturing Company, Ltd. 2 Our decision refers to Appellants’ Brief (App. Br.) filed May 20, 2011, the Examiner’s Answer (Ans.) mailed July 29, 2011, and Appellants’ Reply Brief (Reply Br.) filed September 28, 2011. App App devi the s eal 2012-0 lication 11 ce formed Appellant Represen ubject mat 9. A co pr fo th w an fo in pe in su re 00687 /333,399 thereon, th s’ Figure 7 tative ind ter on app method of mprising: oviding a rming tren e semicon herein the d a second rming a fi the first a rforming an ambien rface of th gion is exp us improv A, depicti hydrog ependent c eal: forming a semicondu ch isolatio ductor sub trench iso active reg rst gate die ctive regio a hydrogen t containi e semicon osed, whe 3 ing the ca ng a conve en anneal laim 9, se semicond ctor subst n regions strate into lation regi ion; lectric ove n; anneal on ng hydrog ductor sub rein after rrier mobi x surface ing t forth bel uctor stru rate; extending the semic ons define r the sem the semic en while a strate in th the hydrog lity.” Id. in the MO ow, is illus cture, the from a top onductor s a first acti iconductor onductor n entirety e second en anneal S after trative of method surface o ubstrate, ve region substrate substrate of the top active step, f Appeal 2012-000687 Application 11/333,399 4 substantially the entirety of the top surface of the second active region forms a convex surface with a curvature; and forming a second gate dielectric over the semiconductor substrate in the second active region. App. Br. A1, Claims App’x. Rejections The Examiner maintains, and Appellants request review of, the following rejections under 35 U.S.C. § 103(a): (a) claims 9-11, 13-14, 16-18, 21-22, 25, and 31 over Horita3 in view of Yamamoto4; (b) claim 12 over Horita and Yamamoto, further in view of Yang5; (c) claim 15 over Horita and Yamamoto, further in view of Lee6; (d) claim 33 over Horita and Yamamoto, further in view of Nakamura7; (e) claims 19, 26, 28-29, and 32 over Yamamoto in view of Lee; and (f) claim 27 over Yamamoto and Lee, further in view of Horita. With respect to Rejection (a), Appellants confine their arguments to the rejection of independent claims 9 and 22. In accordance with 37 C.F.R. § 41.37(c)(1)(vii), we select claims 9 and 22 as representative for resolving the issues arising for Rejection (a). Rejections (b) through (d) stand or fall with the decision with regard to Rejection (a) as Appellants do not advance any additional arguments directed to those rejections. With respect to 3 US 2002/0005529 A1, published January 17, 2002. 4 US 2006/0001108 A1, published January 5, 2006. 5 US 2005/0167750 A1, published August 4, 2005. 6 US 2006/0008961 A1, published January 12, 2006. 7 US 2005/0062080 A1, published March 24, 2005. Appeal 2012-000687 Application 11/333,399 5 Rejection (e), Appellants confine their arguments to the rejection of claim 19. We, therefore, select claim 19 as representative. Rejection (f) stands or falls with the decision with regard to Rejection (e). ANALYSIS Rejection for Claims 9 and 22 over Horita and Yamamoto The Examiner finds Horita discloses a method of forming a semiconductor structure comprising forming trench isolation regions extending from the top into the semiconductor substrate to define one or more active regions; forming a gate dielectric over the semiconductor substrate in the active regions; performing a hydrogen anneal on the semiconductor substrate so that the cross-sectional shape of the upper edge portion of the active region is formed into a circular arc; and forming a gate dielectric (gate insulating film) over the semiconductor substrate in the active region. Ans. 4-5. The Examiner acknowledges that Horita lacks the teaching of first and second active regions and, therefore, that the hydrogen annealing is performed while the entire top surface in the second active region is exposed. Id. at 5 (emphasis added). 8 However, the Examiner finds Horita provides for multiple active regions in the recitation of “at least one active region” (Horita, ¶ [0037]), and in other embodiments (Horita, ¶¶ [0048], [0050], [0052]). Id. The Examiner looks to the teaching of Yamamoto for an explicit teaching of first and second active regions separated by trench isolation 8 We note claim 9 does not require that hydrogen annealing be performed on the second active region only. Appeal 2012-000687 Application 11/333,399 6 regions, wherein the hydrogen anneal is performed while the entire top surface of the semiconductor substrate in the second active region is exposed. Id. at 5-6. The Examiner concludes it would have been obvious to one of ordinary skill in the art to provide Horita with first and second active regions such that the hydrogen annealing is performed while the entire top surface in the second active region is exposed to allow field effect transistors with different properties to be formed. Id. at 6. The Examiner finds the convex curvature of the surface of the second active region is a passive (inherent) result of the claimed steps, which are disclosed by both Horita and Yamamoto. According to the Examiner, “[i]f the claimed active steps are all the same, then the shape should be the same.” Id. Alternatively, the Examiner determines that “if the shape is not the same, then there is some random variation in possible resultant shapes that would be discovered during routine experimentation and optimization.” Id. Appellants argue that Horita fails to explicitly or inherently disclose the claimed features of claims 9 and 22. App. Br. 13-20. Particularly, Appellants argue that Horita does not teach “substantially the entirety of the top surface of the second active region” either forms a convex surface with a curvature (claim 9), or is rounded (claim 22). Id. at 13. Appellants assert that Horita only teaches a planarized portion between two upper edge portions that are “‘formed into a circular arc’” or “formed into a rounded cross-sectional shape having a radius of curvature” as shown in Fig. 11. Id. App App at 14 Fig below most surfa also porti is no Fig of th curv eal 2012-0 lication 11 . ure 11 of PP The Exa ), where , or substa ce with a shows, in ons of PP t so readil ures 23 an A centra e top surfa ature” (cla 00687 /333,399 Horita, sho 1 and PP2 miner resp the upper ntially the curvature. Figure 23 1 have a sm y apparent d 24 of Ho using low l issue bef ce of the s im 9) or “i wing upp having a r onds that edge porti entirety, o Ans. 26. (also depic all radius . Id. rita show versus h ore us is th econd acti s rounded 7 er edge po ounded cr Horita sho ons have a f the top s In contras ted below of curvatu ing differe igh oxidati e meaning ve region ” (claim 22 rtions of th oss-sectio ws, in Fig n enlarged urface of t, the Exam ), where th re, the cu nt curvatu on temper of “subst forms a co ). The Ex e projecte nal shape ure 24 (rep radius of PP1 forms iner find e upper e rvature of res of PP1 ature antially th nvex surf aminer ta d regions roduced curvature, a convex s Horita dge the surfac produced e entirety ace with a kes the e Appeal 2012-000687 Application 11/333,399 8 position that in the absence of a definition in the Specification, the term “substantially” has the ordinary dictionary meaning of “being largely but not wholly that which is specified.” Id. at 25. As such, the Examiner finds Horita’s Figure 24 shows that “‘most but not all’” of the upper surface of PP1 forms a convex surface with a curvature, or is rounded. Id. at 26. On the other hand, citing Phillips v. AWH Corp., 415 F.3d 1301 (Fed. Cir. 2005), Appellants argue that the Examiner fails to consider “substantially” in a manner consistent with the disclosure of the Specification. Reply Br. 5-6. According to Appellants, the Specification describes surface 41 of Fig. 7A as “substantially flat, ‘although a slight curvature may exist.’” Id. at 6, citing Spec. ¶ [0026]. Therefore, Appellants contend a skilled artisan would understand the claimed term “substantially” allows for a slight flatness, but not Horita’s significant intentionally planarized portion between two upper edge portions. Id. We begin, appropriately, with the claim’s words. See Amazon.com, Inc. v. Barnesandnoble.com, Inc., 239 F.3d 1343, 1351 (Fed. Cir. 2001) (“Only when a claim is properly understood can a determination be made . . . whether the prior art anticipates and/or renders obvious the claimed invention.”); In re Donaldson Co., 16 F.3d 1189, 1192 (Fed. Cir. 1994). During examination, claim terms are given their broadest reasonable construction consistent with the specification. In re ICON Health & Fitness, Inc., 496 F.3d 1374, 1379 (Fed. Cir. 2007). In general, words used in a claim are accorded their ordinary and customary meaning. Honeywell Int’l Inc. v. Universal Avionics Sys. Corp., 488 F.3d 982, 992 (Fed. Cir. 2007). Under a broadest reasonable interpretation, words of the claim must be given their plain meaning, unless such meaning is inconsistent with the Appeal 2012-000687 Application 11/333,399 9 specification. However, limitations from the Specification must not be read into the claims. Sjolund v. Musland, 847 F.2d 1573, 1581 (Fed. Cir. 1988) (“[W]hile it is true that claims are to be interpreted in light of the specification and with a view to ascertaining the invention, it does not follow that limitations from the specification may be read into the claims.”); see also In re Am. Acad. of Sci. Tech. Ctr., 367 F.3d 1359, 1369 (Fed. Cir. 2004) (“We have cautioned against reading limitations into a claim from the preferred embodiment described in the specification, even if it is the only embodiment described, absent clear disclaimer in the specification.”) Looking to Appellants’ Specification, the Examiner finds no description of the limits on how much the top surface must form a convex surface with a curvature or is rounded. Ans. 25. We note the Specification only discloses that “the surface 40 in the active region 100 has a convex surface with curvature, as illustrated in Figure 7A. In one exemplary embodiment, the convex surface is substantially rounded . . .” Spec. ¶ [0024]. In addition, the Specification teaches that “[d]epending on the widths of the isolation separation regions or the active regions, this curvature or the extent of the curvature varies.” Id. Moreover, the Specification teaches The roundness of the surface 40 of the region 100 is affected by various factors, such as the composition of the semiconductor substrate 20 and the length L of the active region 100. Different temperatures, hydrogen pressures and anneal durations may be required to form rounded surface 40 with a desired curvature. One skilled in the art can find suitable temperatures, pressures and anneal durations through routine experiments. Appeal 2012-000687 Application 11/333,399 10 Id. at ¶ [0025]. We further note that the factors and conditions under which the curvature of surface 40 is achieved in Fig. 7A are not described. The “desired curvature” is also not further defined in the Specification. We conclude that the claim recitation is sufficiently broad to encompass the preferred embodiment of Fig. 7A and any “desired curvatures,” including the convex surface of PP1 having a curvature shown in Horita’s Fig. 24. Such an interpretation is consistent with the disclosure of Appellants’ Specification. Since we are satisfied that Horita’s Figure 24 and attendant written description meets the claim recitation that substantially the entirety of the top surface of the active region forms a convex surface with a curvature (claim 9) and is rounded (claim 22), we need not reach the Examiner’s alternative positions that Horita either inherently meets this recitation or would meet this recitation through routine optimization, nor Appellants’ arguments directed against these alternative positions. Accordingly, Appellants have not shown reversible error in the Examiner’s rejection. We will sustain the Examiner’s Section 103 rejections of claims 9 and 22, and their dependent claims, over Horita and Yamamoto, alone or further in view of any of Yang, Lee and Nakamura. Rejection for Claim 19 over Yamamoto and Lee The Examiner finds that Yamamoto (Fig. 5A-G) discloses a method of forming a semiconductor structure comprising the steps of forming trench isolation regions 2 in the semiconductor substrate, wherein the trench isolation regions define a first active region (high voltage region) and a second active region (low voltage region); forming a first gate dielectric 4 Appeal 2012-000687 Application 11/333,399 11 over the semiconductor substrate in the first active region; performing a hydrogen anneal (rapid thermal hydrogen anneal or RTH) on the semiconductor substrate in an ambient containing substantially pure hydrogen, wherein the second active region forms a round surface; and forming a second gate dielectric 6 over the round surface and a second gate electrode 7 over the second gate dielectric. Ans. 16-19. The Examiner finds that the “round surface having a curvature” limitation is met by Yamamoto’s disclosure that RTH results in corners being “‘more rounded’” and “‘the flatness of the active region 3 is increased.’” Id. at 18. Further, the Examiner finds Yamamoto’s process steps and mechanism of shape change (diffusion of silicon atoms) are the same as in the claimed method, the results (the shape) should be the same. Id. Alternatively, the Examiner finds that though the shape may be slightly different, variations in the resultant shape would have been discovered during routine experimentation and optimization. Id. at 18-19. The Examiner acknowledges that Yamamoto fails to disclose that the hydrogen annealing is performed after forming the first gate electrode, but finds that Lee teaches hydrogen annealing after forming the first gate electrode. Id. at 19. Appellants argue that Yamamoto does not explicitly or inherently disclose the “round surface having a curvature” or the same process steps as recited in the claims. App. Br. 21-22, 24. Rather, Appellants urge that Yamamoto describes a flat portion between rounded corners as shown in Fig. 5E (depicted below). Id. at 22. Appeal 2012-000687 Application 11/333,399 12 Figure 5E of Yamamoto, depicting a stage in forming a semiconductor device Appellants argue that Yamamoto in fact teaches away from the claimed invention in stating that as a result of RTH, “flatness of the active region 3 is increased and its corners are rounded.” App. Br. 12; Yamamoto ¶ [0041]. Further, Appellants argue that Yamamoto does not recognize the desire for a rounded surface to improve mobility or describe any result-effective variables that would motivate experimentation and optimization by the ordinary artisan. App. Br. 24-25. Appellants’ arguments are persuasive of reversible error. In the rejection, the Examiner finds that the “round surface having a curvature” limitation has been met because Yamamoto discloses RTH results in corners being “more rounded” and “the flatness of the active region 3 is increased.” The Examiner considers that if the flatness is “increased,” it is not flat. Ans. 18, 33. However, as noted by the Appellants, a surface of increased flatness does not mean that it is a round surface. For example, as Appellants note, the increased flatness may be a reduction in surface roughness. Reply Br. 12. The Examiner has failed to supply the requisite facts showing that Appeal 2012-000687 Application 11/333,399 13 Yamamoto explicitly or inherently discloses the claimed “rounded surface having a curvature.” The Examiner maintains that because Yamamoto and the claimed process both perform a hydrogen anneal, the resultant shape would be the same. Ans. 18, 36. However, the Examiner fails to direct us to any evidence establishing that performing RTH under the conditions disclosed in Yamamoto inherently produces “a round surface having a curvature that extends from one trench isolation region across the entire second active region to another trench isolation region” as claim 19 requires. As indicated above the Examiner has not shown that one skilled in the art following the teachings of Yamamoto would have arrived at the claimed invention, in the absence of Appellants’ disclosure. Accordingly, we will not sustain the Examiner’s Section 103 rejection of claims 19, 26, 28-29, and 32 over Yamamoto and Lee. Further, with regard to the rejection of claim 27, we note the Examiner does not rely on Horita to remedy the deficiencies in the Yamamoto and Lee combination. We therefore will not sustain the Examiner’s obviousness rejection of claim 27. ORDER Upon consideration of the record, and for the reasons given above and in the Answer, it is ORDERED that the decision of the Examiner rejecting under 35 U.S.C. § 103(a) claims 9-11, 13-14, 16-18, 21-22, 25, and 31 over Horita in view of Yamamoto; claim 12 over Horita and Yamamoto, further in view Appeal 2012-000687 Application 11/333,399 14 of Yang; claim 15 over Horita and Yamamoto, further in view of Lee; and claim 33 over Horita and Yamamoto, further in view of Nakamura is affirmed; and FURTHER ORDERED that the decision of the Examiner rejecting under 35 U.S.C. § 103(a) claims 19, 26, 28-29, and 32 over Yamamoto in view of Lee; and claim 27 over Yamamoto and Lee, further in view of Horita is reversed. No time period for taking any subsequent action in connection with this appeal may be extended under 37 C.F.R. 1.136(a)(1). AFFIRMED-IN-PART cdc Copy with citationCopy as parenthetical citation