Chemistry for etching quaternary interface layers on InGaAsP mostly formed between GaAs and InxGa(1-x)P layers

摘要

A method is provided for etching quaternary interface layers of InxGa1-xAsyP1-y which are formed between layers of GaAs and InGaP in heterojunction bipolar transistors (HBTs). In accordance with the method, the interface is exposed by etching the GaAs layer with an etchant that is selective to InGaP. The interface is then etched with a dilute aqueous solution of HCl and H2O2 that is selective to InGaP. The controlled etching provided by this methodology allows HBTs to be manufactured with more sophisticated, near ideal designs which may contain multiple GaAs/InGaP interfaces.