Federal Circuit Affirms IPR Decisions for BeSang and the Noninfringement Judgment for Micron on BeSang's Vertical Memory Patent.

Two rulings on one patent

The IPR appeals are Micron Technology, Inc. v. BeSang Inc., No. 2025-1320, and Intel Corp. v. BeSang Inc., No. 2025-1377 (Fed. Cir. Oct. 30, 2026) (nonprecedential), from the Board's decisions in IPR2023-00900 (November 13, 2024) and IPR2023-00991 (December 11, 2024). The appellants in No. 2025-1320 are Micron Technology, Inc., Micron Semiconductor Products, Inc., and Micron Technology Texas, LLC. The district court appeal is BeSang Inc. v. Micron Technology, Inc., No. 2026-1085, from No. 2:23-cv-00028-JRG-RSP before Judge Rodney Gilstrap. The court affirmed that judgment per curiam under Federal Circuit Rule 36.

What the claims recite

The '702 patent is titled "Vertical Memory Device Structures." Claim 1 recites a semiconductor memory structure with a substrate that has electrical devices formed in it and at least one dielectric layer and at least one interconnect layer above it, and a first stackable add-on layer containing a plurality of vertically oriented semiconductor memory cells "separated from each other by dielectric material." The add-on layer is bonded to the substrate layer farthest from the substrate's bottom surface, and the memory cell is a DRAM having at least one transistor. Claim 13 recites a substrate with electrical devices and a dielectric layer above them, and "a stackable add-on layer having a plurality of vertically oriented semiconductor memory cells" bonded to the dielectric layer, where the cells are nonvolatile memory cells having at least one transistor.

Micron's appeal

Micron challenged claims 13-17. The Board found that Micron had not shown claim 13 obvious over Watanabe, U.S. Patent 5,091,762, or over Watanabe combined with U.S. Patent 6,881,994 (the Lee Patent). On the Watanabe-only ground, the Board concluded that Watanabe was not enabled because it disclosed bonding its stacked layers with a thermal process at 900 to 1000 degrees Celsius, which expert testimony showed would risk destroying the electronic components in the underlying substrate. The court held that this was a factual finding supported by substantial evidence, not an implicit claim construction importing a temperature limit, writing that "[t]hat is a conclusion on enablement, not claim construction." It also rejected Micron's "thermal budget" argument that the high-temperature bonding could occur for a short time, because the Board considered and rejected that evidence. On the combination ground, the court held that the same expert testimony supported the Board's finding of no motivation to combine, and that the Board did not require Micron to show a specific improvement. Having affirmed on those grounds, it did not address Micron's nonvolatile memory argument.

Intel's appeal

Intel challenged claims 1 and 13-17. For claim 13, the Board found that Intel had not shown that the Lee Application, U.S. Patent Application 2002/0028541, taught "a stackable add-on layer having a plurality of vertically oriented semiconductor memory cells." Intel did not appeal that finding, and the court held that the Board did not abuse its discretion in reading the petition to rely only on the Lee Application for that limitation. For claim 1, the Board found that the combination of Park, U.S. Patent 5,571,730, and Kim, U.S. Patent Application 2003/0157748, did not disclose memory cells separated from each other by dielectric material, because Park's adjoining cells share a plate electrode and gate electrode with only some dielectric material between them. The court held that substantial evidence supported that finding and rejected Intel's argument that the Board implicitly construed the claim to require electrical separation, noting that Intel itself had argued the cells must be electrically separated for proper operation. The court concluded that "[t]he respective claims were not shown to have been unpatentable."

The noninfringement judgment

BeSang sued the Micron entities in the Eastern District of Texas in January 2023, and in December 2023 the court granted the parties' joint motion to stay the case pending resolution of certain inter partes review petitions. After the Board's decisions, Magistrate Judge Roy S. Payne issued a claim construction order on August 5, 2025, and on August 27, 2025, Judge Gilstrap overruled BeSang's objections and adopted it. The parties then agreed that the construction that "a 'stackable add-on layer' cannot be a layer formed in situ by sequential deposition on the dielectric layer" was case-dispositive in Micron's favor, and they stipulated that, under that construction, the accused products do not infringe any claim of the '702 patent. On September 17, 2025, the court entered final judgment of non-infringement, dismissed Micron's counterclaims without prejudice, and extended the time for a bill of costs or a motion for attorney fees until 30 days after the Federal Circuit's mandate. The Federal Circuit's October 30, 2026 Rule 36 judgment affirmed.

What to watch next

Watch for any petition for rehearing in either appeal, and for any bill of costs or motion for attorney fees in the Eastern District of Texas, which the final judgment allows until 30 days after the Federal Circuit's mandate.