Method of detecting an end point of plasma treatment

Abstract

The present invention relates to a method of and apparatus for detecting an end point of plasma treatment of a specimen. There is included selecting plasma spectrum having a characteristic wavelength from the plasma spectrum generating at the time of reaction in the plasma treatment of a specimen, setting a disregarding time for the plasma treatment end point detection, assuming, at the stage when the disregarding time for treatment end point detection has elapsed, a quantity of the selected plasma spectrum up to the time of said stage based on a quantity of same plasma spectrum at the time of said stage and a variation with the time in the last said quantity of plasma spectrum, and detecting the reaction time end point from the assumed quantity of plasma spectrum and an actual quantity of the same plasma spectrum after the time of said stage thereby making it possible to prevent erroneous detection of the end point of reaction in the plasma treatment and detect accurately the same even when the reaction time of the plasma treatment is short.