The authors present a novel T-gate fabrication process which takes advantage of the unique high-resolution property of the low-k dielectric material, hydrogen silsesquioxane (HSQ), as a negative tone electron beam resist. By optimizing layout design and process parameters, the authors demonstrate similar to 30 nm gap between two HSQ rectangular geometries, which is then used to define the T-gate footprint and support the T gate. An InGaAs/InAlAs/InP high electron mobility transistor with 80 nm gate length was fabricated using this HSQ-based resist technique. Excellent dc and rf performances are presented. (c) 2007 American Vacuum Society.