Intel is the first company to do so with others, such as TSMC and Samsung looking to do so at 14-nm.At IEDM Intel plans to show the way again with a compound semiconductor version that promises faster transistors than silicon. Intel technical executives have in the past tipped InGaAs, possibly embedded on silicon for ease of manufacturing and to carry non-critical circuitry as a way forward for the semiconductor industry. Intel Fellow Paolo Gargini has proposed the integration of an InGaAs quantum-well FET with a high-K dielectric gate stack. (see Intel's Gargini pushes III-V-on-silicon as 2015 transistor option).
Radosavljevic's IEDM presentation on InGaAs FinFET devices with improved electrostatic performance, due to the fin shape, looks set to be in-line with that proposal. However, until now, though, the best performing III-V MOSFETs have been planar types, scaled to 10-nm gate lengths and with ultra-thin-bodies.
Two key metrics are sub-threshold slope (the steeper it is, the more abruptly the device can switch) and drain-induced barrier lowering, or DIBL (the smaller it is, the less sensitive the device is to drain voltage and the more efficiently it can turn off). Long-channel devices exhibited a subthreshold slope of 66 mV/decade, close to the theoretical minimum of 60 mV/decade, while DIBL of short gate length devices was significantly improved over best-in-class planar III-V MOS devices. The better electrostatics of these devices comes from their narrow fin width and high-quality high-k gate dielectric.
The image above is a cross-sectional scanning electron micrograph of the 3-D tri-gate InGaAs device structures perpendicular to the fin direction, after fin and gate recess etches and before high-k/metal gate deposition, with a 30-nm fin-width and 50-nm height.
The Intel paper is number 33.1 Electrostatics Improvements in 3-D Tri-Gate Over Ultra-Thin Body Planar InGaAs Quantum Well Field Effect Transistors with High-K Gate Dielectric and Scaled Gate-to-Drain/Gate-to-Source Separation, M. Radosavljevic et al, Intel/IQE.
