Dry etching characteristics of In1-x-y Ga x Al y as alloys in CCl2F2:Ar and CH4:H2:Ar discharges |
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Authors: | S. J. Pearton R. F. Kopf |
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Affiliation: | (1) AT&T Bell Laboratories Murray Hill, 07974 New Jersey |
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Abstract: | The etching characteristics of InGaAlAs alloys lattice-matched to InP were investigated using low pressure (1 mTorr) electron cyclotron resonance CH4:H2:Ar or CCl2F2:Ar discharges with additional radiofrequency biasing of the samples. Using CCl2F2:Ar discharges with ≥250V negative bias it is possible to obtain equi-rate etching of the material for all compositions between In0.53Ga0.47As and In0.52Al0.48As. At lower bias values, formation of A1F3 on the surface leads to an inhibition of the etch rates. By making use of the differential etch rates of InGaAlAs layers of different compositions in CH4:H2:Ar mixtures, it is possible to choose dc bias values that allow one to stop the etching at a pre-selected depth in a multi-layer structure. For example, for -150 V bias, one can etch through In0.53Ga0.47As, In0.53Ga0.40Al0.07As and Ino.53Ga0.30Al0.17As layers, and stop at an underlying layer with composition In0.53Ga0.20Al0.27As. |
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Keywords: | Dry etching InGaAlAs CCl2F2:Ar CH4:H2:Ar |
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