A common strategic question in inter partes review proceedings is whether you should proceed on an anticipation ground, arguing that a specific limitation is inherently disclosed, or convert the ground into an obviousness ground, using an explicit disclosure in a secondary reference to demonstrate the unpatentability of a claim. The perils of going with an inherent anticipation argument, of course, include the additional burden of proving that a reference necessarily discloses the feature, even if it is not explicitly disclosed. As such, it is worthwhile considering Spansion Inc., Spansion LLC, and Spansion (Thailand) Ltd., v. Macronix International Co., Ltd., (IPR2014-01116; U.S. Pat. No. 6,522,360) wherein the Board rejected an inherency argument made by Petitioner.
The ‘360 patent relates to a circuit layout on a substrate of a semiconductor wafer that is suitable for reducing defects during a chemical mechanical polishing (CMP) process. The process has several key paramenters, including having an average polishing pressure during the process. The substrate comprises a plurality of strips, and the circuit layout comprises two structures linked by said strips. Decision at 2-4.
Petitioner argued that a prior art reference inherently disclosed the claim limitation “at least two strips of second circuit structure located on said substrate of said semiconductor wafer, each of said two strips of second circuit structure respectively linking the front end and the rear end of said plurality of strips of said first circuit structure”. Id. at 8. The Board disagreed, finding that Petitioner did not sufficiently address the functional language of the claim limitation as inherently disclosed in the reference. Id. at 8-9. Specifically, the Board found that Petitioner did not provide enough evidence that the prior art process would apply an average polishing pressure across the circuit grid arrangement of the reference. The Board criticized Petitioner’s reliance on a bare opinion presented in expert testimony, which essentially recited verbatim the patentability analysis presented in the Petition. In other words, rather than provide objective factual support for the inherency argument, Petitioner’s expert testimony essentially signed off the arguments set forth in the petition. Accordingly, the Board rejected Patent Challenger’s inherency argument and denied the petition as to the ground which depended on inherent disclosure in the prior art. Id. at 10.