Novel sloped etch process for 15nm InAlAs/InGaAs metamorphic HEMTs

We developed a new technology that reduces gate length with modified sloped etch process to fabricate nanometer scale high-electron mobility transistors (HEMTs). The polymer deposition and Si₃N₄ etching with positive slope make this technology realizable. A HEMT with this technology has merits of both fine length definition beyond the limit of an electron beam (E-beam) lithography system and overcoming the metal filling problem caused by a high aspect ratio. Using this technology, we could get 15 nm gate length from initial 40 nm line pattern. The fabricated 15 nm InAlAs/InGaAs metamorphic HEMTs (MHEMTs) have high DC and RF performance characteristics, a transconductance of 1.6 S/mm, a cutoff frequency fT of 580 GHz.