New Dry-Etch Chemistries for III-V Semiconductors

Abstract

AbstractFor some dry etching applications in III-V semiconductors, such as via hole formation in InP substrates, the currently used plasma chemistries have etch rates that are up to a factor of 30 too slow. We report on the development of 3 new classes of discharge chemistries, namely C12/CH4 /H2/Ar at 150°C (yielding InP etch rates of >1 μm · min−1 at 1 mTorr and –80V dc), HBr/H2 for selective etching of InGaAs over AlInAs, and iodine-based plasmas (HI/H2, CH3 I/H2) that offer rapid anisotropic etching of all III-V materials at room temperature. In all cases, Electron Cyclotron Resonance sources (either multipolar or magnetic mirror) with additional rf biasing of the sample position are utilized to obtain low damage pattern transfer processes that generally use metal contacts on device structures as self-aligned etch masks. The temperature dependence of etch rates with these new chemistries display non-Arrhenius behavior in the range 50-250°C and a detailed study of the phenomenon are reported. Electrical, optical and chemical analysis of the etched surfaces show that it is possible to achieve essentially damage-free pattern transfer.