ETCHING MONITORING APPARATUS, ETCHING APPARATUS, AND METHOD OF DETECTING ETCHING DEPTH

摘要

An etching monitor unit, an etching device and an etching depth detecting method are provided to detect the etching depth by suppressing the influence of the distortion even in case the distortion of the interfering wave is in phase. An etching monitor unit(20) monitors the etching depth using the reflection light. A light source(21) irradiates the light to the processed article. An optical detector(25) detects the coherent light which is changed by the reflection light from the upper side or the surface of the etched layer. A control device(28) comprises the frequency analysis unit, an etching rate production unit and an etching depth production unit. The frequency analysis unit(26A) calculates the frequency of the interfering waveform. The etching rate production unit(26B) produces the etching rate using the frequency of the interfering waveform. The etching depth production unit(26C) calculates the etching depth from the etching rate.