EVALUATION METHOD FOR OXIDE SEMICONDUCTOR THIN FILM, QUALITY CONTROL METHOD FOR OXIDE SEMICONDUCTOR THIN FILM, AND EVALUATION ELEMENT AND EVALUATION DEVICE USED IN SAID EVALUATION METHOD

摘要

Provided are: a method for measuring and evaluating (predicting or estimating) stress stability of an oxide semiconductor thin film in a contactless manner; and a quality control method for an oxide semiconductor. This evaluation method comprises a first step and a second step. The first step includes: subjecting an oxide semiconductor thin film to irradiation with both excitation light and microwave radiation; stopping the irradiation with the excitation light after the maximum intensity of reflected wave of the microwave radiation, which varies with the irradiation of the excitation light, from the thin film has been observed; and thereafter measuring a variation in the reflectance with which the microwave radiation is reflected by the thin film. The second step includes: calculating, from the variation in the reflectance, a parameter that corresponds to slow attenuation observed about 1 µs after the stopping; and thus evaluating the stress stability of the oxide semiconductor.