MIRROR-SURFACE EVALUATING METHOD OF GALLIUM ARSENIDE WAFER

PROBLEM TO BE SOLVED: To enable the surface of a gallium arsenide wafer to be quickly and accurately evaluated by a method wherein the mirror-surface of the gallium arsenide wafer is cleaned, dried out, and exposed to a nitric acid atmosphere after the gallium arsenide wafer is subjected to mirror-surface polishing, and then it is judged that the mirror-surface of the wafer is dried up well or not, observing whether stains are left on the mirror surface or not. SOLUTION: A gallium arsenide wafer specimen 1 whose surface is mirror- polished is cleaned and then dried up by the use of isopropyl alcohol vapor. Then, the gallium arsenide wafer specimen 1 is fixed above the liquid level of an acid-proof vessel 4 filled with nitric acid liquid 3 so as to set its mirror- surface 2 parallel with the liquid surface of nitric acid liquid 3 separating it from the liquid surface by a prescribed space, and the mirror-surface 2 is exposed to a nitric acid vapor atmosphere for a prescribed time. Then, it is visually checked in a condensed light by an inspector whether the mirror surface 2 of the gallium arsenide wafer specimen 1 is good or not. When a trace left by a flow of isopropyl alcohol is found as stains, it is judged that the mirror surface 2 is irregularly dried up.