Tech firms detail high-k developments

IBM, Intel, Taiwan Semiconductor Manufacturing Co. and the NEC-Toshiba duo are expected to present papers on 32nm processes with high-k and metal gates at this week's International Electron Devices Meeting (IEDM).

The biggest surprise is silicon foundry giant TSMC, which isn't supposed to have its high-k/metal-gate solution ready until the 28nm node.

IBM's "fab club" has recently disclosed the details of its 32nm process with high-k and metal gates. This week, the group will present a paper on a 32nm FinFET with a high-k/metal-gate scheme.

Also at IEDM, the NEC-Toshiba duo will present a "cost-conscious" high-k/metal-gate scheme. Last week, Intel Corp. rolled out its 32nm process, based on a second-generation, high-k/metal-gate scheme.

There are two basic approaches to the next-generation gate stack in logic designs. IBM's "fab club" is using a gate-first approach to the high-k/metal-gate scheme, while Intel is deploying a rival replacement-gate technology. In a gate-first approach, the gate stack is formed before the source and drain, as in a conventional CMOS process. Replacement-gate technologies are a gate-last approach, where the gate stack is formed after source and drain.

At IEDM, TSMC will present a paper about a 32nm process, which includes a high-k/metal-gate scheme based on a gate-first technology. A 0.15?? SRAM cell was developed by using a hafnium-based material and 193nm immersion lithography with a numerical aperture of 1.35, according to TSMC's paper.

TSMC's high-k material has been scaled to 10?. "Drive currents of 1340/940-uA/um are achieved at I_off=nA/?m, V_dd=1V, 30nm physical gate length and 130nm gate pitch," according to the paper.

It's unclear if TSMC will offer the technology at 32nm, however. The company said it plans to roll out high-k at 28nm, which TSMC considers as its "full-node" technology.

Gate-first
In a separate paper, the team of NEC Corp. and Toshiba Corp. disclosed that it has developed a 32nm process, with a single-exposure lithography technology and a "gate-first" high-k/metal-gate process. The chip makers have demonstrated a SRAM cell of 0.124-micron2 and a gate density of 3650kGate/mm?, according to the paper.

At various times, IBM and its technology partners have talked about their 32nm process with high-k and metal gates. IBM's partners include Advanced Micro Devices, Chartered Semiconductor, Freescale Semiconductor, Infineon Technologies, Samsung Electronics, STMicroelectronics and Toshiba.

Moving beyond the planar transistor, IBM, AMD, Freescale and Toshiba will present a FinFET with high-k and metal gates for the 32nm node and beyond. An SRAM cell was devised at areas down to 0.128??, which is said to be the world's smallest FinFET cell to date, according to the paper.

Using 22nm design rules, the cell was fabricated using a CMOS process flow and e-beam lithography. The cell was also devised using "off-center design contacts and L-shaped bars," according to the paper.

In the cell, fin pitch was 80nm, gate pitch and L_g were 110nm and 30nm. To enable high-k and metal gates, CVD-based HfO₂, PVD TiN and polysilicon were deposited on the Fin portion of the device.

- Mark LaPedus
EE Times