Comparison of and plasma chemistries for dry etching of InGaAlP alloys
Etch rates above have been obtained for and plasma etching of , and under electron cyclotron resonance (ECR) conditions. The etched surface morphologies are a strong function of the ratio of chlorine radicals to total ion density in the discharges, and are smoother in . Non-optimized etching conditions produce rough surfaces characterized by the presence of chlorine and boron-containing residues and substantial post-oxidation. We believe that the high ion flux available under ECR conditions provides efficient sputtering of the normally involatile , and thus a selvedge layer of this material is prevented from forming. Therefore the etch rates are much higher and the surface morphologies smoother in ECR discharges. The etch rates of are much lower than the other two ternary compounds and are independent of composition over the range x = 0.05 - 0.70 for fixed plasma conditions.