METHOD FOR MONITORING TRENCH FORMING PROCESS IN REAL TIME AT JOB SITE

摘要

PROBLEM TO BE SOLVED: To provide a method by which a trench forming process can be monitored in real time at a job site. SOLUTION: A wafer is put in a plasma etching device (57) and plasma is generated (58). The surface of a wafer having a large area is irradiated with a radiant ray having a designated wavelength at a vertical incident angle through an inspection hole (59). Reflected light rays are collected and impressed upon a spectrometer and an interferometer type primary signal S is generated (60) and the signal S is simultaneously applied upon two filters (61). Of the two filters, a low-pass filter outputs first secondary signals S1 containing the data about the deposition speed and the thickness of a re-deposited layer and a band-pass filter outputs second secondary signals S2 containing the data about the etching rate and depth of a trench. Thus the filtrated signals are monitored in a standardized way (62) and the thickness of the re-deposited SiO2 layer and trench forming parameters, such as the depth of the trench, etc., are accurately measured in real time so that the terminating point of etching can be decided accurately.