Patent ID: 8123901

Claim:
An etching apparatus selectively etching a peripheral portion of a wafer, comprising: a stage on which said wafer is placed; an etchant supply port allowing through which an etchant etching said peripheral portion is supplied; an etching-interfering agent supply port through which an etching-interfering agent interfering supply of said etchant to said center of said wafer is supplied; a movable alignment mechanism taking part in wafer alignment on said stage, the alignment mechanism being configured to equalize a width of removal of the peripheral portion of the wafer; a peripheral removal width observation unit observing the width of removal of said peripheral portion of said wafer after the etching, the peripheral removal width observation unit being configured to discriminate an etched peripheral region from an other region; an output unit outputting said width of removal of said peripheral portion of said wafer observed by said peripheral removal width observation unit; and a control unit controlling a stroke of said alignment mechanism, based on displacement of the wafer in a previous processing and based on said width of removal of said peripheral portion of said wafer output by said output unit, wherein said peripheral removal width observation unit includes an optical microscope configured to discriminate the etched peripheral region from the other region based on a contrast therebetween, and wherein said control unit calculates a displacement of a center of said wafer, based on said width of removal of said peripheral portion of said wafer observed by said peripheral removal width observation unit, and controls said stroke of said alignment mechanism based on said displacement of said center of said wafer.