A 150 GHz sub-0.1- mu m E/D MODFET MSI process

We report a method for fabricating sub-0.1- mu m gates using conventional optical contact lithography, exploiting self-limiting notch formation in conformal PECVD oxide between ohmic contacts, and the limited lateral etch of oxide by RIE. The resulting gate openings in the oxide are very narrow ( approximately=700 AA), and quite uniform ( sigma <0.2x). 154 GHz current gain cutoff frequency has been extrapolated for a pseudomorphic InGaAs-channel E-MODFET made in this way. Functioning prescalers have been fabricated and characterized on-wafer.<
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