Micron v. BeSang — Federal Circuit Upholds Memory-Patent Claims in Two IPR Appeals

Background

BeSang owns a patent directed to three-dimensional semiconductor memory structures. Micron and Intel filed separate inter partes review petitions challenging claims as obvious over combinations of prior-art references. The Patent Trial and Appeal Board rejected the challenges, concluding that the petitioners had not shown that the proposed combinations disclosed every limitation or that a skilled artisan would have made the proposed modifications.

The appeals were consolidated. Micron disputed the Board’s treatment of a limitation involving a semiconductor layer positioned between memory-cell layers. Intel challenged the Board’s handling of limitations concerning conductive channels, dielectric separation between cells, and combinations built around references known as Lee, Aspar, Kim, and Park.

The Court’s Holding

The Federal Circuit affirmed both Board decisions. For Micron’s challenge, the panel held that substantial evidence supported the Board’s reading of the prior art and its finding that the proposed combination did not teach the claimed arrangement. The court declined to replace the Board’s supported technical factfinding with Micron’s competing interpretation.

Intel’s arguments failed for both procedural and evidentiary reasons. Its petition expressly relied on the Lee application for one limitation and separated that argument under its own subheading. The Board therefore acted within its discretion when it evaluated the petition as written instead of reconstructing a different theory on appeal. Because Intel did not successfully challenge the Board’s finding that Lee failed to teach the limitation, its related obviousness combinations could not succeed.

The Board also reasonably found that Park did not disclose memory cells separated from one another by dielectric material. Park’s figures showed adjoining cells sharing plate and gate electrodes, with only some dielectric material between them. Intel itself had framed electrical separation as necessary for proper operation, so the Board’s comparison did not impose an unannounced claim construction.

Key Takeaways

• IPR petitioners must present each obviousness theory clearly in the petition; the Board need not assemble a better theory from scattered evidence.
• Technical findings supported by patent figures and expert evidence receive deferential substantial-evidence review.
• An argument framed by the petitioner as requiring electrical separation cannot later be recast as an improper claim construction when the Board uses that premise.

Why It Matters

The ruling reinforces that the petition defines the boundaries of an inter partes review. Semiconductor patents often turn on fine structural distinctions visible in figures and layer arrangements. Petitioners need to connect each reference to each claim limitation expressly, while patent owners can prevail by exposing gaps between a proposed combination and the physical architecture the claims require.