We make real-time spectroscopic rotating compensator ellipsometer for real time measurement and in-situ measurement. We study a method to make Poly silicon after depositing amomhous silicon thin film by dc sputter system at different temperature and pressure. Amorphous silicon films of 30㎚ thickness were deposited on the Ni substrate, and then ITO films of 20㎚ thickness were deposited on the a-Si films. The sampie were crystallized below 300℃ in the electric field applied between the Ni and ITO.