当具有足够大发散角的柱面光照射在匀厚金属薄膜表面时, 由表面等离子体振荡产生的光反射率角分布是膜厚的函数, 用CCD接收反射光分布信息并经过计算机分析处理,可实时、在线测量10nm内的铬、钛等金属膜厚, 这类金属的复介电常数的实部相对虚部是较小的负数, 故具有强反射锐峰及较平坦的吸收峰, 该两峰点可作为膜厚测量依据的特征标记点, 并通过建库进行曲线匹配而获得膜厚数值。实验结果表明, 该方法的平均测量误差可低于0.4nm。

When the surface of metal film with uniform thickness is irradiated by cylindrical wave with sufficient large divergence angle, the reflectivity of the angular distribution caused by surface plasma resonance is the function of film thickness. The distribution information of reflected light is received by using CCD and analyzed by computer to realize real time, online measurement of metal film as Cr or Ti with thickness being within 10nm. For this kind of mental, the real part of complex dielectric relative to imaginary part is smaller negative number, so the metal has the strong reflection sharp peak and relative flat absorption peak. The two peak points can be used as feature mark points of film thickness measuring basis, and through building up database the thickness of film can be obtained by curve matching. The experiment shows that the average error of measurement can be less than 0.4 nm.