0.15 /spl mu/m T-shaped gate pseudomorphic HEMT fabricated using a new optical lithographic technique

The authors propose a new optical lithographic technique to form a 0.15 /spl mu/m length T-shaped gate. The lithographic technique is composed of PSM, low temperature PECVD of SiN, concurrent development and planarisation of the photoresist. By using this technique, a 0.15 /spl mu/m AlGaAs-InGaAs-GaAs PHEMT was successfully fabricated, and with a transconductance of 498 mS mm and cutoff frequency of 62.4 GHz.