PLASMA-ETCHING OF INGAP, ALINP AND ALGAP IN BCL3 ENVIRONMENTS

The etch rates of InGaP, AlInP and AlGaP are more than an order of mag nitude larger in microwave-enhanced BCl3/Ar discharges relative to con ventional reactive ion etch (RIE) conditions. This is due to the incre ased atomic radical and ion densities. While RIE discharges produce ro ugh, non-stoichiometric surfaces of InGaP and AlInP due to the formati on of an InCl3 selvedge layer, the surfaces of samples etched under EC R conditions are generally smooth and stoichiometric. This difference is found to be due to the efficient ion-assisted desorption of InCl3 u nder high ion density conditions. The advantage of this process is tha t simple BCl3-based plasma chemistries can be employed for all III-V s emiconductors, whereas previously CH4/H-2 was used for In-containing m aterials and chlorine chemistries for Ga-containing materials. The etc h rate of AlGaP is substantially slower than the other two materials, which can be explained on the basis of the bonding differences.