A novel process for adjusting the gate-drain spacing in InP-HEMTs with

To enable mass production of InP-HEMTs operating in microwave and THz bands with T shaped gates as narrow as 30 nm, industry friendly processes for source/drain contacts are urgently needed. So far, although a self-aligned technique using pre-fabricated T shaped gates as masks has been reported, the limited adjustments of the gate-source/gate-drain spacings by this process restricts the device performance optimization. In this work, 30 nm T shaped gates by a novel bilayer of RE650/UV5 are successfully fabricated. Using the T shaped gates as masks, a self-aligned process with angled evaporation of contacts has been developed, which offers us a new degree of freedom to adjust the locations of the contacts in a large range for the optimization of the device structure. By numerical simulations, the influences of the gate-source/gate-drain spacings on the device performance such as the DC/RF characteristics, the spatial distributions of both electric fields and the carrier density, etc., have been studied. The property of InP-HEMTs with the contacts by the traditional alignment is also compared. Optimized spacings for maximizing the device performances are figured out. The progress achieved in this work should be an important guide in both the manufacturing process development and the construction of the device structure.