Follow-up system for etch process monitoring

Claim 1

A follow-up system for monitoring the etching process in RIE equipment to produce high-resolution and reproducible patterns in a structure to be etched, having a treatment chamber for containing a plasma, which produces a glow discharge during the etching process, and provided with a quartz view port and a susceptor that holds a semiconductor wafer bearing said structure, said system comprising: (a) an optical fiber means disposed close to said view port and perpendicular to said wafer; (b) spectrometer means for filtering one line of a determined species that is produced during the etching process by the glow discharge to select a characteristic wavelength λ, and generating a variable output signal representative of the intensity of that line having maxima and minima depending on the etched thickness of said structure; and (c) means for detecting said output signal so that the etched thickness is accurately measured on a continuous basis.