Dry etching of submicron gratings for InP laser structures-comparison of HI/H2, CH4/H2and C2H6/H2plasma chemistries

Three different discharge chemistries for dry etching of gratings in InP laser structures have been investigated. Each type of plasma (HI/H 2 , CH 4 /H 2 , C 2 H 6 /H 2 ) yields controllable etch rates that are constant with etching time. Lower DC self-biases can be used with HI/H 2 because of the greater volatility of the group III etch products. The C 2 H 6 /H 2 mixture produces excessive polymer deposition on the photoresist mask at process pressures >or=10 mTorr. The rectangular shape of the gratings is preserved during overgrowth by organo-metallic vapour phase epitaxy.