Patent ID: 9601396
Date: 2017-03-21
CPC Classifications: G03F,H01L

Claim:
1. A method of determining a photoresist trimming process endpoint comprises: directing an optical signal to a surface of a patterned photoresist layer disposed on a film stack formed on a substrate in a processing chamber; performing a trimming process on the substrate to trim the patterned photoresist layer disposed on the film stack from a first width to a second width in the processing chamber, wherein the patterned photoresist layer exposes a portion of the film stack uncovered by the patterned photoresist layer during the trimming process; performing an etching process to etch a portion of the film stack exposed by the trimmed patterned photoresist layer; continuously directing the optical signal to the surface of the trimmed patterned photoresist layer during the trimming and the etching process; collecting a return reflected optical signal reflected from the trimmed patterned photoresist layer; determining a change of reflected intensify of the return reflected optical signal as collected; calculating a photoresist thickness loss based on the change of the reflected intensity; and determining an endpoint for each trimming process based on the photoresist thickness loss as calculated after each etching process.