CL2 AND SICL4 REACTIVE ION ETCHING OF IN-BASED III-V SEMICONDUCTORS

The reactive ion etching of InAs, InSb, InP, InGaAs, and InAlAs in SiCl4/Ar or Cl2/Ar discharges was investigated as a function of the plasma parameters power density, pressure, and relative composition as well as etching time. The etch rates of all of these materials with the exception of InP are faster in SiCl4/Ar in comparison to Cl2/Ar, and show a similar dependence on power density and discharge composition. The variation of etch rates with pressure, however, are quite different for the two gas mixtures, with all of the materials going through a maximum at 60–80 mtorr for SiCl4/Ar, while continuing to show a monotonic increase with pressure for Cl2/Ar. The surface morphologies after RIE with either type of discharge are generally quite rough, although smooth etching can be obtained under appropriate conditions. Increased reverse bias currents are observed in Au/n-type InP Schottky diodes after RIE, with higher currents for low pressure or high self-bias etching. Photoluminescence decreases from InP are also observed after RIE, ranging in magnitude from 2–10 times. The depth of point defect introduction by energetic ion bombardment is limited to <200Å in InP for RIE at 50 mtorr and dc biases on the samples of 50V. Chlorine-containing residues are present typically to a depth of ~40Å on all of the material after RIE in either type of discharge. The addition of SF6 to both gas mixtures leads to a high selectivity for InP and InGaAs over InAlAs because of the formation of a thin involatile layer of AlF3 on the InAlAs. © 1990, The Electrochemical Society, Inc. All rights reserved.