CH4:H2:Ar rf/ECR Plasma Etching of GaAs and InP


A comparative study of CH4:H2, and CH4:H2:Ar rf-plasma and microwave electron cyclotron resonance (ECR) plasma etching of GaAs and InP is presented. The study is in two parts; p](i) Kinetic studies of GaAs and InP etch rates as a function of the constituent gas flow rates, applied rf and microwave powers, substrate temperature and position. The results indicate that CH4:H2:Ar ECR etching of GaAs is 10× more efficient in the utilisation of the CH4 precursor gas than rf-plasmas. However, the absolute etch rates are lower (70 nm min−1 for rf and 25 nm min−1 for rf biassed ECR-plasmas).The effect of etching conditions on InP morphology is also examined. p](ii) The study of electrical “damage” in GaAs/AlGaAs high electron mobility transistor (HEMT) Hall bar structures, was investigated by ECR-plasma etching off the top GaAs capping layer. Results indicate that ECR-plasma etching with an rf-bias between 0V and −30V does not significantly effect the electrical characteristics of such devices at 300K, with some degredation at 1.2 K.

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This work was supported under the auspices of the SERC's LDS initiative. The authors would like to thank M.Pepper and M. J.Kelly for their support in this work. We also acknowledge D.C.Clary for helpful discussions, also A.J.Murrell and K.B.Papworth for their technical assistance.

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Correspondence to Victor. J. Law or S. G. Ingram or G. A. C. Jones or R. C. Grimwood or H. Royal.

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Law, V.J., Ingram, S.G., Jones, G.A.C. et al. CH4:H2:Ar rf/ECR Plasma Etching of GaAs and InP. MRS Online Proceedings Library 223, 191 (1991).

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