INSPECTION METHOD OF SEMICONDUCTORRSUBSTRATE CARRIER DENSITY DESTRIBUTION

摘要

PURPOSE:To measure the carrier-density distribution on the surface of a n-type substrate making use of the distribution and thickness of an oxide film produced by applying a constant voltage regarding the substrate as an anode and an electrolyte as a cathode. CONSTITUTION:A breakdown voltage is lower as the carrier density of a n-type semiconductor substrate is higher. When an applied voltage is higher than the breakdown voltage, on the other hand, the thickness of the formed oxide film is in proportion to the applied voltage without depending upon the carrier density, and the oxide film of constant thickness can be formed by a contant voltage. Further, the thickness of an anode oxide film has constant relation to the tone of the film and can be judged from the color. This anode oxidation should be done in a dark room and requires the prevention of the facilitation by light. In this way, the carrier-density distribution and its density can both be measured in short time without a breakdown.