Selective dry etching of InGaP over GaAs in inductively coupled plasmas
By exploiting the relatively high volatility of In etch products in CH4/H2 discharges, we were able to obtain a maximum selectivity for InGaP over GaAs of ∼20 at low ion energies and fluxes. Three different inert gas additives to CH4/H2 were examined, with Ar producing higher selectivities than He or Xe. This process is attractive for selective removal of the InGaP emitter in the fabrication of heterojunction bipolar transistors.