AVS 45th International Symposium
    Electronic Materials and Processing Division Thursday Sessions
       Session EM2-ThA

Paper EM2-ThA5
Electron Cyclotron Resonance Induced Surface and Subsurface Defects in GaAs Exposed to a Chlorine/Ar Plasma

Thursday, November 5, 1998, 3:20 pm, Room 316

Session: Non-destructive Testing and In-situ Diagnostics
Presenter: O.J. Glembocki, Naval Research Laboratory
Authors: O.J. Glembocki, Naval Research Laboratory
R.T. Holm, Naval Research Laboratory
W.E. Carlos, Naval Research Laboratory
D. Leonhardt, Naval Research Laboratory
C.R. Eddy, Boston University
K.K. Ko, University of Michigan
S.W. Pang, University of Michigan
D.S. Katzer, Naval Research Laboratory
Correspondent: Click to Email
The detection and control of dry etched induced electronic damage is critical to the formation of high quality semiconductor devices. In order to avoid ambient contamination, we have used in-situ photoreflectance (PR) to study the behavior the surface electric fields and surface photovoltage in both n-type and p-type GaAs exposed to a chlorine/Ar plasma generated by an electron resonance cyclotron source. By monitoring the desorption of the Ga and As chlorides, we find that the removal of Ga is the rate limiting step. This leads to a surface that is Ga rich and decorated by Ga vacancies which change the surface pinning position in both n- and p-GaAs. In addition, the etched surfaces show a decreased surface photovoltage. By using in-situ chemical etching/passivation with chlorine, we are able to uncover subsurface damage and show that it is distinctly different from the Ga vacancies formed on the surface. We find that the bulk etch damage has an exponential profile and that it is amphoteric, behaving as a very deep donor in n-GaAs and a deep acceptor in p-GaAs. Our experiments further indicate that both states of this defect lie below midgap. Possible candidates are point defects such as interstitials. Spin resonance results will be used in discussing the nature of the defects.