IP Law Daily, PATENT—Fed. Cir.: PTAB’s findings of unpatentability for miniaturized semiconductor patents affirmed, (Apr 21, 2026)

By Brian Craig, J.D.

The claims are obvious given the claim language, the absence of lexicography or disavowal, and the specification.

Concluding that the patent claims for a miniaturized semiconductor device for two patents owned by Katana Silicon Technologies LLC are obvious and invalid, the U.S. Court of Appeals for the Federal Circuit has affirmed a decision from the Patent Trial and Appeal Board in a inter partes review challenge brought by Micron Technology, Inc. In affirming the Board’s findings, the Federal Circuit concluded that the claims are obvious given the claim language, the absence of lexicography or disavowal, and the specification’s described solutions to the problems of conventional devices and methods of manufacture. Absent lexicography or disavowal, the court will not depart from the plain meaning of the claims, and the appeals court found no clear disavowal of using adhesive agents to form an adhesion layer or lexicography that would exclude such an adhesion layer in the specification or prosecution history (Katana Silicon Technologies LLC v. Micron Technology, Inc., No. 24-2100 (Fed. Cir. Apr. 21, 2026)).

Katana Silicon Technologies LLC (“Katana”) owns U.S. Patent Nos. RE38,806 (“the ’806 Patent”) and 6,352,879 (“the ’879 Patent”). The patents describe semiconductor device having a structure substantially miniaturized to a chip size, i.e., a CSP (Chip Size Package) structure, and a method of manufacturing such a semiconductor device. Micron Technology, Inc. (“Micron”) filed three petitions for inter partes review, arguing that International Patent Application Publication No. WO 96/13066, in combination with other references not pertinent to this appeal, rendered all claims of the ’806 Patent and the ’879 Patents obvious. The Board agreed with Micron that the claims are obvious. Patent owner Katana appealed. The sole dispute in the appeal was whether the Board erred in construing the claim term “adhesion layer” as “a layer that adheres” in the pat.

Claim language. The Federal Circuit first examined the claim language in determining whether the Board properly construed the patent claims. Looking first at the claim language, the term “adhesion layer” merely requires a layer that provides adhesion. That is, “adhesion” is an adjective modifying the noun “layer” to specify the type or purpose of the layer. Nothing in the claim language requires a fully-formed or “preformed” adhesion layer where no further processing is required. Had the patentee intended to limit the claims to a pre-formed adhesion layer with no further required processing, it could have included language in the claims to that effect.

No disavowal. Furthermore, the Federal Circuit concluded that the absence of lexicography or disavowal supports the Board’s conclusion that the patent claims are obvious. Absent lexicography or disavowal, the court will not depart from the plain meaning of the claims. In this case, there is no clear disavowal of using adhesive agents such as glue or paste to form an adhesion layer or lexicography that would exclude such an adhesion layer in the specification or prosecution history. The specification does not limit an adhesion layer to a thermo-compression sheet but instead discloses a thermo-compression sheet as an example of an adhesion layer.

Specification. Finally, the Federal Circuit found that the specification supports the Board’s claim construction. Where there is no evidence suggesting that the ordinary meaning of adhesion layer is limited to a thermo-compression sheet or even to a fully pre-formed layer, the appeals court was not inclined to import limitations from the preferred embodiments into the claimed invention. The panel read these embodiments in light of the rest of the specification. The Federal Circuit was not convinced that these exemplary embodiments represent clear disclaimer of other types of adhesion layers.

Conclusion. Given the claim language, the absence of lexicography or disavowal, and the specification’s described solutions to the problems of conventional devices and methods of manufacture, the Federal Circuit agreed with the Board’s findings that the claims are obvious. Therefore, the Federal Circuit affirmed the Board’s conclusion of unpatentability.

The Case is No. 24-2100.

Judge: Stoll, K.

Attorneys: Howard Lithaw Lim (Carter Arnett PLLC) for Katana Silicon Technologies LLC. Andrew Dufresne (Perkins Coie LLP) for Micron Technology, Inc.

Companies: Katana Silicon Technologies LLC; Micron Technology, Inc.

Cases: Patent FedCirNews GCNNews