IN-SITU X-RAY REFLECTIVITY MEASUREMENT OF THIN FILM GROWTH. Chih-Hao Lee and Sung-Yuh Tseng, Department of Nuclear Engineering and Engineering Physics, National Tsing Hua University, Hsinchu, Taiwan, 30043

X-ray reflectivity method was used to measure in-situ the thickness and surface roughness of a thin film during deposition growth. Intensity oscillation as function of time can be observed as the film thickness grows. The oscillation amplitude is damped as the surface roughness increase. The experiment procedure is similiar to ellipsometry or RHLEED. While only kinematic theory is needed to interpret the experiment data, the X-ray reflectivity method is much easier to fit the model. In this method, the measurement sensitivity of the film thickness can be selected by changing the specular angle. A higher incidence angle is more sensitive to thinner layer. As the specular angle approaches anti-Bragg angle, the measurement is sensitive to the monolayer growth of the thin film.