10-nm Fin-Width InGaSb p-Channel FinFETs

Recently, III-V multi-gate MOSFETs have attracted great interest to replace silicon in future CMOS tech- nology. This is due to III-V semiconductor’s outstanding carrier transport properties. Although impressive n-type transistors have been demonstrated on materials such as InAs and InGaAs, research in III-V p-channel devices is lagging. The antimonide system, such as InGaSb, has the highest hole mobility among all III-V compound semiconductors, and its hole mobility can be further improved by applying compressive strain. Therefore, InGaSb is regarded as one of the most promising semiconductors to replace p channel Si MOSFETs.
FinFET is a nonplanar transistor in which the conducting channel sticks out of the wafer top in a similar way as the fin of a shark above the ocean surface. In a FinFET, the gate wraps around the fin helping to reduce leakage current when the device is OFF and mitigating short-channel effects. FinFET is the state of the art transistor architecture in current Si CMOS technology, and demonstration of III-V FinFETs is imperative.

In this work, we greatly advance the state-of-the- art of antimonide-based electronics by demonstrating deeply-scaled InGaSb p-channel FinFETs through a fully CMOS-compatible fabrication process. To achieve this, we have developed a novel antimonide-compatible digital etch technology, which has a consistent etch rate of 2 nm/cycle on InGaSb. It is the first demonstration of digital etch on InGaSb-based transistors of any kind. The new technologies enabled the first fabricated InGaSb FinFETs featuring fin widths down to 10 nm and gate lengths of 20 nm. Single fin transistors with fin width of 10 nm and channel height of 23 nm (aspect ratio of 2.3) have achieved a record transconductance of 160 μS/μm at VDS = 0.5 V. When normalized to device footprint, we achieve a record transconductance of 704 μS/μm. Digital etch has been shown to effectively improve the turn-off characteristics of the devices.

This work not only highlights the potential of InGaSb p-channel multigate MOSFETs, but also pushes the state-of-the-art of antimonide fabrication technology significantly for general applications in which the antimonide-based compounds can shine.