SELF-ALIGNED SHALLOW JUNCTION MJFET (METAL JUNCTION FET) FOR HIGHER TURN-ON AND BREAKDOWN VOLTAGES

Abstract

Simple self-aligned p++-gate formation technology for a junction field-effect transistor (JFET) using elemental shallow Zn diffusion from patterned Au/Zn gate metal is reported in this paper. This diffusion technology makes it possible to control a very shallow p++-layer less than 50 nm. The metal junction FET (MJFET) shows about 0.3 V higher gate turn-on voltage in the forward bias and much larger reverse breakdown voltage than the conventional Al-gate MESFET with similar transconductances, typically 200 mS / mm for 1.5-mum gate length quasi-enhancement, and 90 mS / mm for 4-mum gate length deep depletion devices.