(Received July 2, 1982; accepted for publication August 21, 1982)
An H3PO4–H2O2–H2O solution is studied for possible use in the etching of germanium. The solution can be roughly classified into two ternary regions according to its etching characteristics: a (with a low H2O2 concentration) and b (with a high H2O2 concentration). Solutions in region b provide reproducible smooth and uniform surfaces. This solution can be used with SiO2 films and photoresists as a preferential etching mask material without dissolution or separation. It is suitable for processing germanium devices.