CHEMICAL ETCHING OF InGaP AND GaAs IN SOLUTIONS OF HCl, H₃PO₄, AND H₂O₂

Jaroslava Škriniarová et al

   We present the measured etch rates of lattice matched InGaP and GaAs, in HCl : H₃PO : H₂O₂ solutions with variable contents of H₃PO₄ and H₂O₂. The content of H₃PO₄ in the solution affected the etch rates markedly, by contrast, the content of H₂O₂ had only a weak influence. The ageing of the HCl : H₃PO₄ : H₂O₂ (1:10:1) etchant did not alter the etch rate for InGaP, while that for GaAs decreased notably. For this solution we measured the temperature dependence of the etch rate. An increase in temperature from 20 to 44^oC resulted into a growth in the etch rate by about a factor of three, which reveals the reaction limited nature of the etch process. Without the presence of H₂O₂ in the solution one can achieve highly selective etching of InGaP over GaAs. The etch rate for InGaP varied rapidly with the content of HCl in the solutions of x, HCl : H₃PO₄ and x, HCl : H₂O.

Keywords: InGaP, wet etching, etch rate

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