Use of CF3,Br/Al, discharges for reactive ion etching of III-V semiconductors

Abstract

The reactive ion etching of GaAs, InP, InGaAs, and InAlAs in CF3Br/Ar discharges was investigated as a function of both plasma power density (0.56-1.3 W - cm−2) and total pressure (10-40 mTorr) The etch rate of GaAs in 19CF3Br:1Ar discharges at 10 m Torr increases linearly with power density, from 600 A min−1 at 0.56 W · cm−2, to 1550 A · min at 1.3 W · cm−2. The in-based materials show linear increases in etch rates only for power densities above − 1.0 W · cm−2. These etch rates are comparable to those obtained with CCI2F2:O2 mixtures under the same conditions. Smooth surface morphologies and vertical sidewalls are obtained over a wide range of plasma parameters. Reductions in the near-surface carrier concentration in n-type GaAs are evident for etching with power densities of >0.8 W cm−2, due to the introduction of deep level trapping centers. At 1.3 W· cm−2, the Schottky barrier height of TiPtAu contacts on GaAs is reduced from 0.74 to 0.53 eV as a result of this damage, and the photoluminescent intensity from the material is degraded. Alter RIE, we detect the presence of both F and Br on the surface of all of the semiconductors. This contamination is worse than with CCl2F2-based mixtures. High-power etching with CF3Br/Ar together with Al-containing electrodes can lead to the presence of a substantial layer of aluminum oxide on the samples if the moisture content in the reactor is appreciable.