Selective dry etching of InGaP over GaAs in inductively coupled plasmas

By exploiting the relatively high volatility of In etch products in CH4/H-2 discharges, we were able to obtain a maximum selectivity for InGaP over Ga As of similar to 20 at low ion energies and fluxes. Three different inert g as additives to CH4/H-2 were examined, with Ar producing higher selectiviti es than He or Xe. This process is attractive for selective removal of the I nGaP emitter in the fabrication of heterojunction bipolar transistors.