Title :
A new self-aligned AlGaAs/GaAs HBT based on refractory emitter and base electrodes
Author :
Nittono, Takumi ; Nagata, Koichi ; Nakajima, Osaake ; Ishibashi, Tadao
Author_Institution :
NTT LSI Lab., Kanagawa, Japan
Abstract :
A self-alignment technique for AlGaAs/GaAs heterojunction bipolar transistors (HBTs) using refractory metal film, W, as the emitter and base electrodes is presented. A nonalloyed contact formation combined with selective reactive ion etching of W or WSi/sub x/ against GaAs and SiO/sub 2/ produces a self-aligned structure. An emitter contact that is thermally stable is obtained by using a Zn diffusion process to make the extrinsic base contact layer. An f/sub T/ value as high as 82 GHz was obtained. The self-alignment technique combined with the Zn diffusion process will achieve a much higher f/sub T/ if a thinner base HBT structure is used.<>
Keywords :
III-V semiconductors; aluminium compounds; gallium arsenide; heterojunction bipolar transistors; sputter etching; tungsten; 82 GHz; AlGaAs-GaAs; AlGaAs:Zn; HBTs; SiO/sub 2/; W; WSi/sub x/; Zn diffusion process; base electrodes; cutoff frequency; emitter contact; emitter electrode; extrinsic base contact layer; heterojunction bipolar transistors; nonalloyed contact formation; refractory metal film; selective reactive ion etching; self-alignment technique; Circuits; Dielectrics; Electrodes; Epitaxial layers; Gallium arsenide; Heterojunction bipolar transistors; Optical films; Sputter etching; Wet etching; Zinc;
Journal_Title :
Electron Device Letters, IEEE
