Applied Materials, Inc.
OPTICAL CABLE FOR INTERFEROMETRIC ENDPOINT DETECTION

Abstract:

Disclosed herein is an endpoint detection having an optical bundle configured to emit light through a ceiling of a processing chamber. The optical bundle has a plurality of fibers configured to transmit the light from a light source towards a substrate and is configured to receive light reflected from the substrate. The plurality of fibers include a first emitting fiber and a first receiving fiber. The first receiving fiber is radially disposed at a pairing angle from the first emitting fiber, and is configured to receive light emitted from the first emitting fiber. The plurality of fibers further include a second emitting fiber and a second receiving fiber. The second receiving fiber is radially disposed at the pairing angle from the second emitting fiber. The second receiving fiber is configured to receive light originating from the second emitting fiber. The pairing angle is between about 175 degrees and 185 degrees.