Title :
Metallurgical stability of ohmic contacts on thin base InP/InGaAs/InP HBT´s
Author :
Chor, E.F. ; Malik, R.J. ; Hamm, R.A. ; Ryan, R.
Author_Institution :
AT&T Bell Labs., Murray Hill, NJ, USA
Abstract :
The metallurgical stability of ohmic contacts: Pt, Pt/Ti, Au/Ti, Au/Pt/Ti, and Au/Pt/Ti/W, on a 500 /spl Aring/ thick p/sup +/-InGaAs base of InP/InGaAs/InP HBTs have been investigated as a function of anneal temperature. All contacts were stable after a 300/spl deg/C-30 s anneal. Pt contact failed at 350/spl deg/C whereas Pt/Ti, Au/Ti, and Au/Pt/Ti contacts failed at 400/spl deg/C. The failure mechanism was a collector leakage short owing to the penetration of Pt or Ti through the thin base. Only HBTs with Au/Pt/Ti/W contact were still functional after a 400/spl deg/C anneal with no apparent shift in the turn-on voltage for the emitter and collector junctions.
Keywords :
III-V semiconductors; annealing; failure analysis; gallium arsenide; heterojunction bipolar transistors; indium compounds; ohmic contacts; semiconductor device metallisation; semiconductor device reliability; semiconductor-metal boundaries; thermal stability; 30 s; 300 C; 350 C; 400 C; 500 A; Au-Pt-Ti; Au-Pt-Ti-W; Au-Ti; InP-InGaAs-InP; Pt; Pt-Ti; anneal temperature; collector leakage short; failure mechanism; metallurgical stability; nonalloyed contacts; ohmic contacts; p/sup +/-InGaAs base; thin base HBT; Annealing; Contact resistance; Gold; Heterojunction bipolar transistors; Indium gallium arsenide; Indium phosphide; Metallization; Ohmic contacts; Stability; Temperature;
Journal_Title :
Electron Device Letters, IEEE
