InGaAs FinFETs Directly Integrated on Silicon by Selective Growth in Oxide Cavities

Abstract

III-V semiconductors are being considered as promising candidates to replace silicon channel for low-power logic and RF applications in advanced technology nodes. InGaAs is particularly suitable as the channel material in n-type metal-oxide-semiconductor field-effect transistors (MOSFETs), due to its high electron mobility. In the present work, we report on InGaAs FinFETs monolithically integrated on silicon substrates. The InGaAs channels are created by metal–organic chemical vapor deposition (MOCVD) epitaxial growth within oxide cavities, a technique referred to as template-assisted selective epitaxy (TASE), which allows for the local integration of different III-V semiconductors on silicon. FinFETs with a gate length down to 20nm are fabricated based on a CMOS-compatible replacement-metal-gate process flow. This includes self-aligned source-drain n+ InGaAs regrown contacts as well as 4 nm source-drain spacers for gate-contacts isolation. The InGaAs material was examined by scanning transmission electron microscopy (STEM) and the epitaxial structures showed good crystal quality. Furthermore, we demonstrate a controlled InGaAs digital etching process to create doped extensions underneath the source-drain spacer regions. We report a device with gate length of 90 nm and fin width of 40 nm showing on-current of 100 µA/µm and subthreshold slope of about 85 mV/dec.