진동 둔감 광 간섭계를 이용한 실리콘 웨이퍼 표면형상 측정

Abstract

We devised a vibration-insensitive interferometer with a common-path scheme of generating the reference wave directly by transmitting the measurement wave through a single-mode fiber. This fiber-diffraction interferometer enables to cancel out the dominating vibration effect encountered commonly in both the reference and measurement waves in the due course of the two waves’ interference. Besides, to suppresss parasite vibration disturbances caused to interferometer hardware components, a special type of spatial phase-shifter is added to capture four phase-shifted interferograms simultaneously without time delay using a single camera shot. The proposed interferometer system is capable of providing a high level of vibration immunity that is found useful for testing large scaledsilicon wafer's surface profile when sufficient ground isolation for anti-vibration is not feasible.