Compact and high-speed ellipsometer

A compact and high-speed ellipsometer system with a new ellipsometric analyzer has been developed. Its size is 130x65x25mm, and the weight 400g including a light source and analyzers with no moving part. With an automatic x-O stage, it takes only 20 seconds to obtain an area distribution map of a thin film-thickness on a 8-inch wafer at 2mm pitch of 6,000 points. Its compactness and high-speed might make it widely applicable to various processes. 1.][NTRODUCTION Real-time measurement of film thickness is required in steel making processes. At NKK in electrical tin-coating line(ETL), we have to control thickness of oil on steel sheets ranging from 50 A to 400A continuously. However, there were no adequate method for angstrom order thickness at high speed. Ellipsometer is one of the most commonly used instruments to measure thickness or refractive index of thin films. Though many types have been examined, the null ellipsometer and the photometric ellipsometer (the rotating analyzer type) are widely used today[1]. But these instruments are rather large and heavy. They occupy around 50 cm square area and weigh 30kg at least. Moreover, they need a few seconds to measure a point and the target is required to be stati