The device roadmap past gate-all-around (GAA) nanosheets has a leading candidate: the forksheet. Its defining feature is a dielectric wall inserted between the n-type and p-type devices, allowing them to be placed much closer together than two independent GAA stacks - shrinking the cell. Taiwan Semiconductor Manufacturing Co., Ltd. opened 2024 with a forksheet grant.

US11862700B2, "Semiconductor device structure including forksheet transistors and methods of forming the same" (issued 2024-01-02), is classified in H01L 29/42392 (gate electrodes for GAA) with H01L 21/823828 and 823857 (CMOS integration) and H01L 27/092 (complementary FET). The claim is on the forksheet structure - and the limitation that distinguishes it is the wall separating the complementary devices.

“A semiconductor device structure, along with methods of forming such, are described.”— U.S. Patent No. 11,862,700 source

Construe the wall. In a conventional CMOS layout, n and p devices need a minimum separation set by well boundaries and isolation. The forksheet's dielectric wall lets them abut more tightly because the wall provides the isolation in a thin vertical structure. The claim turns on that separating wall and how the nanosheets sit on either side of it.

The design-around space is in the isolation scheme between n and p. A competitor achieving tight n/p spacing by another means - a different isolation structure, or the complementary-FET (CFET) approach of stacking n over p vertically - sits outside a claim that requires the specific forksheet wall. Forksheet and CFET are competing post-GAA paths, and they are claimed separately.

Filing on forksheet on the first business day of 2024 signals TSMC staking an early position on a device that is still years from volume. This is research-frontier IP, valuable as a priority-date anchor in a contest that includes imec (which originated the forksheet concept), Samsung, and Intel.

For an R&D strategist, this grant is a roadmap signal: TSMC is hedging its post-nanosheet bets, with forksheet IP alongside its GAA and packaging filings. The priority date matters because the forksheet-versus-CFET decision is one of the defining device questions of the late-2020s, and early claims will shape the freedom-to-operate landscape when it arrives.