Patent ID: 6088096
Filing Date: 2000-07-11
Classification: G01N,H01J

Abstract:
An end-point detector for a plasma etcher, the detector comprising:at least one converging lens for receiving strip-like plasma light produced between electrodes of the plasma etcher; andspectroscopic means, having a slit located at a rear-side focal plane of the converging lens, for detecting an etching end time point from a time-based variation of spectrum light intensity of the plasma light which has been converged at the slit and has passed through the slit,wherein said converging lens has a pupil diameter of not greater than ##EQU4## where W is a width of a short side of the strip-like plasma light produced between the electrodes, 1 is a distance between an end of each electrode and a pupil face of the converging lens, NAm is a numerical aperture required by the spectroscopic means, and h is a width of a short side of the slit of the spectro-scopic means, andwherein the converging lens has a numerical aperture of not less than NAm.