Fabrication of 30 nm T gates using SiNx as a supporting and definition layer

A new process has been developed to fabricate 30 nm T gates for high performance metal-semiconductor held effect transistors and high electron mobility transistors. The fabrication of short gate length T gates becomes increasingly difficult as the footwidth of the gate is made smaller and this is particularly true when the footwidth is less than 50 nm. In this process a thin SiNx layer is deposited on the substrate prior to the application of a bilayer of poly (methyl methacrylate)/Shipley UVIII resist. After resist patterning by electron beam lithography the nitride layer is etched at a low bias voltage that causes negligible substrate damage. This process step helps to define the gate footwidth and improves mechanical stability of the gate. The measured gate resistance was 375 Omega /mm. (C) 2000 American Vacuum Society. [S0734-211X(00)12206-1].