A Study on Reliability and Failure Mechanism of T-Shaped Gate HEMTs (Special Section on Reliability)

概要

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This paper describes the reliability on recess type T-shaped gate HEMTs and their major failure mechanism investigated by accelerated life tests and following failure analysis. In this study, high temperature storage tests with a DC bias condition have been conducted on three different recess depths of , 125, and 150 nm. The results have clarified that the shallow recess devices of under 125 nm depth have no degradation in minimum noise figure F_<min> or gain G_a characteristics, indicating that standard HEMT devices, whose recess depth is chosen to be far under 125 nm, possess a sufficient reliability level. However, the devices with deep recess of 150 nm have shown degradation in both F_<min> and G_a. Precise failure analyses including SEM observation and von Mises stress simulation have firstly revealed that the main failure mode in deeply recessed T-shaped gate HEMTs is increase in gate electrode's parasitic resistance R_g, which is caused by separation of "head" and "stem" parts of the T-shaped gate electrode due to thermo-mechanical stress concentration.
社団法人電子情報通信学会の論文
1994-01-25