AVS 46th International Symposium
    Electronic Materials and Processing Division Monday Sessions
       Session EM-MoA

Paper EM-MoA8
Effect of N@sub 2@ Discharge Treatment on AlGaN/GaN HEMT Ohmic Contact Using Inductively Coupled Plasma

Monday, October 25, 1999, 4:20 pm, Room 608

Session: Nitride Processing and Characterization
Presenter: A.P. Zhang, University of Florida
Authors: A.P. Zhang, University of Florida
G. Dang, University of Florida
X.A. Cao, University of Florida
F. Ren, University of Florida
S.J. Pearton, University of Florida
J.M. Van Hove, SVT Associates
P.P. Chow, SVT Associates
R. Hickman, SVT Associates
J.J. Klaasen, SVT Associates
Correspondent: Click to Email
Due to the excellent thermal stability and large energy band-gap of GaN based material system, AlGaN/GaN based high electron mobility transistors (HEMTs) have an excellent potential for high temperature and high power applications. The conventional low resistance n@super +@-cap layer structure used to reduce parasitic resistances in GaAs technology is generally not applied in nitride devices as it is difficult to perform the gate recess step. This is due to the high chemical stability of GaN which makes wet etching very difficult except at high temperatures or under optical stimulation. Mochi has demonstrated that an exposure of Ar or N@sub 2@ discharge to ohmic contact region before the metal deposition showed an improvement of contact resistance. However a systematic study of plasma energy and time has not been performed yet. In this work, we investigate the contact resistance by varying the chuck power from 10-60W and ICP discharge power from 100 to 700W and plasma exposure time from 40 to 80 sec. The effect of anneal temperature was also studied. The ion bombardment sample showed two order of magnitude lower contact resistance than that of un-treated sample. Auger and AFM were also used to analyze the effect of ion bombardment. The photoresist was also optimized for the plasma treatment.