Etching endpoint determination method

Abstract

A microscopic change in a luminous intensity occurring near an etching endpoint is accurately detected, whereby the endpoint of etching is quickly determined. An etching endpoint determination method for determining an endpoint of etching processing in a plasma etching apparatus that introduces a processing gas into a vacuum chamber, produces plasma by feeding high-frequency energy to a introduced processing gas, and uses the produced plasma to perform plasma processing on a workpiece stored in the chamber includes: a step of sampling light of a pre-set wavelength from light emitted by the plasma produced in the vacuum chamber, acquiring as time-sequential data the luminous intensity of the sampled light of the specific wavelength, and computing a regression line on the basis of the acquired time-sequential data; and a step of computing distances in a time-base direction between the regression line and the time-sequential data which are obtained at the first step. An endpoint of etching processing is determined based in the distances in the time-base direction obtained at the second step.