Patent ID: 9640370
Date: 2017-05-02
CPC Classifications: B81C,H01J,H01L

Claim:
1. Etching apparatus for performing an etch operation of globally etching a substrate across its width to expose buried features, including: (a) an etch chamber; (b) a support fixed in place within the etch chamber and dedicated to retain the substrate in the etch chamber, the support having a support surface oriented horizontally such that when the substrate is generally planar and is retained by the support, a face of the substrate to be etched is oriented horizontally generally parallel to the support surface; (c) an illumination source having an optical axis and which emits light propagating in the direction of the optical axis, the illumination source being mounted in the apparatus as oriented relative to the support such that the optical axis of the illumination source extends at an acute angle with respect to the support surface and light emitted by the illumination source will illuminate the face of the substrate, retained by the support on the support surface, at an acute angle with respect to the face; (d) a camera positioned relative to the support to capture light reflected or scattered from the face at an acute angle with respect to the support surface; (e) an edge detector coupled to the camera and configured to detect the appearance of an edge of at least the buried features emerging on the face during the etch operation, and (f) a controller operatively connected to the edge detector and configured to stop the etch operation in response to the appearance of the at least one edge of the buried feature when detected by the edge detector.