AVS 50th International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS2-WeM

Paper PS2-WeM8
Low Energy Electron Enhanced Etching (LE4) of HgCdTe and III-V Semiconductor Materials

Wednesday, November 5, 2003, 10:40 am, Room 315

Session: Etching Difficult Materials
Presenter: J. Kim, University of California, Los Angeles
Authors: J. Kim, University of California, Los Angeles
T.S. Koga, University of California, Los Angeles
C. Miclaus, University of California, Los Angeles
H.P. Gillis, University of California, Los Angeles
M.S. Goorsky, University of California, Los Angeles
G.A. Garwood, Raytheon Infrared Operations
D.R. Rhiger, Raytheon Infrared Operations
S.M. Johnson, Raytheon Infrared Operations
Correspondent: Click to Email
The high energy ion bombardment involved in the reactive ion etching (RIE) process creates damage sites in the HgCdTe material which cause type conversion, among other problems. The ion energy can be reduced by using electron cyclotron resonance (ECR) plasma etching; however, the etched surfaces are not reliably stoichiometric or smooth. We have been exploring a new dry etching technique called low energy electron enhanced etching (LE4) to achieve low-damage, smooth, stoichiometric etched surfaces with high-resolution pattern transfer.@footnote 1@ In the LE4 process, electrons at energies 1-15 eV and reactive species at thermal velocities arrive at the surface. The LE4 technique, because it completely eliminates ion bombardment and relies on low energy electrons to control the etching chemistry, holds promise for eliminating the damage while retaining the beneficial features of RIE. LE4 experiments were performed on non-patterned, or photoresist (PR) mesa patterned Hg1-xCdxTe (x~0.3) epitaxial layers grown by molecular beam epitaxy (MBE) on (211)-oriented Cd1-yZnyTe substrate or (211)-oriented CdTe/Si substrate. In LE4 of HgCdTe, the sample was placed between the cathode and anode in a dc plasma. Dc bias was applied to the backside of the sample to control the electron current density to the surface. A mixture of Ar-CH4-H2-N2 (AMHN) was used as the etching gas. We will summarize results from mechanistic study to optimize etch condition, and demonstrate how electron energy, CH4 concentration, and sample temperature influence the etch rate, surface stoichiometry, and surface roughness. In addition, we will show some results of our AMHN LE4 process for III-V semiconductor materials (GaAs and InP). @FootnoteText@ @footnote 1@ J. Kim, T.S. Koga, H.P. Gillis, M.S. Goorsky, G.A. Garwood, J.B. Varesi, D.R. Rhiger, and S.M. Johnson, Extended Abstracts the 2002 U.S. Workshop on Physics and Chemistry of II-VI Materials 173 (2002).