AMD hit with patent lawsuit over hybrid bonding used in its 3D V-Cache processors

Adeia accuses AMD of violating ten patents tied to 3D chip stacking

by · TechSpot

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What just happened? IP licensing company Adeia has sued AMD in the Western District of Texas, alleging that it used patented hybrid bonding methods in its stacked-cache processors without a license. The case asserts ten patents covering bonding techniques and advanced process node technologies. The company says the lawsuit follow years of unsuccessful licensing talks, while AMD has not commented on the filings.

Adeia's complaints say AMD's recent 3D V-Cache processors rely on hybrid bonding, a method for connecting chips by directly joining planarized copper and dielectrics at fine pitch rather than using solder microbumps, which allow dense, short interconnects between stacked dies to improve bandwidth and power efficiency.

The filing specifies seven patents tied to hybrid bonding and three tied to advanced process nodes, signaling a focus on how the dies are joined and powered in modern 3D integration flows rather than on a single product line. Adeia frames these techniques as foundational IP developed over decades and widely licensed across the semiconductor industry, contending that AMD products have extensively used those inventions without a license.

AMD's 3D V-Cache design stacks a large SRAM chiplet over a compute die to expand L3 capacity and reduce memory latency, using TSMC's SoIC hybrid bonding to couple the layers without solder bumps, increasing interconnect density and reducing energy per bit compared to traditional packaging.

AMD's second-generation V-Cache reports up to 2.5 TB/s of cache-to-core bandwidth, building on a first-gen design that already moved beyond microbump connections with direct copper-to-copper bonds, with bond pitches in the single-digit micron range that help achieve near-monolithic behavior between dies. These technical elements – direct Cu-Cu interfaces, oxide bonding, TSV placement, and micron-scale pitch – are central to the claims around who owns the enabling method and where foundry process IP begins in a stacked CPU.

Few expect near-term product disruption; US courts do not automatically grant injunctions after a finding of infringement, and the Supreme Court's eBay v. MercExchange decision requires courts to weigh a four-factor test before blocking shipments, which makes such relief less common in complex tech cases.

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Early action is more likely at the Patent Trial and Appeal Board, where AMD or partners could seek inter partes review to challenge the asserted claims as too broad or as overlapping with foundry-owned process technologies like SoIC, a typical move in semiconductor IP disputes that tests validity before trial.

Outcomes often land in negotiated licenses, but if Adeia's claims survive initial challenges, the ruling could influence how hybrid bonding method claims are valued relative to foundry implementations in future deals across CPUs and accelerators that depend on direct-bond stacking.