Comparison of ICl and IBr Plasma Chemistries for Etching of InGaAlP Alloys

ICl and IBr provide rapid etching of the ternary alloys InGaP, AlInP,and AlGaP under electron cyclotron resonance conditions. The rates are almost independent of microwave power in the range 400 to 1000 % with typical values of ∼1.5 μm/min with ICl/Ar and ∼0.4 μm/min with IBr/Ar. At low microwave powers (≤750 W), the etched surface morphologies are quite smooth and there is little degradation of photoresist masks. High Al content Al x Ga 1-x P (x ≥ 0.7) alloys appear to be good candidates as etchstop layers in InGaAlP device structures when using these plasma chemistries.