END POINT SYSTEM FOR RESIST RECESS ETCH

摘要

An in-situ method for measuring the endpoint of a resist recess etch process for DRAM trench cell capacitors to determine the buried plate depth on a semiconductor wafer thereof, comprising: placing an IR device on the etch chamber;illuminating the surface of a semiconductor wafer during etching to a resist recess depth with IR radiation from the IR device;detecting reflection spectra from the illuminated surface of the semiconductor wafer with an IR detector;performing a frequency analysis of the reflection spectra and providing a corresponding plurality of wave numbers in response thereto; and utilizing calculating means coupled to the IR detector to calculate the resist recess depth at the illuminated portion of the wafer from the plurality of wave numbers corresponding to the reflection spectra.