Research And Realization Of High-precision Extinction Type Ellipsometry Thickness Gauge

with a comprehensive study on the development of ellipsometer both at home and abroad as well as an analysis of the problems undermining HST-1 ellipsometer such as low effeciency in measuring, poor precision and ISA, this paper applies the master-sercice framework with USB interface into the designing of a precise reflectional null ellipsometer according to the principles by which the null ellipsometer works. Meanwhile this paper focuses on its actual measurement, and the result shows that the newly-designed instrument shows brilliance in precison and speed. The following is what has been done in this thesis:1 The designing of the optics-mechanics system is done in terms of 6 modules, which provides convenience for installing both erect and level structures in the ellipsometer;2 The master-slave framework with USB interface is adopted to eliminate the application difficulty of ISA interface;3 Based on the subdivision technology of evenly-rotating step motor powered by current vector with constant amplitude, this paper designs driving circuit for step motor,which is evenly as well as precisely divided. The designing combines data table generated by computer and manual adjustment so as to obtain the linearity between the step angle and the number of subdivided steps. Thus, the subdivision angle is close to 0.025° ;4 The software for the measuring of slave instrument, for the operating interface of master and data processing of the ellipsometric parameters are well disigned and programmed;5 "Circulational Step-counting" proposed in this thesis improves the location of polarizer and analyzer in terms of precision and stablization;6 "Average Value of the 2 Points at the Same Level" functions effeciently in getting the nulling angles free from noise so as to help a lot in seeking the nulling angles as well as improve the stablization and precision of the last action;7 "The Separation of Optical Angle from Mechanical One" isproposed, and as a result,the random errors that often happens in measuring the nulling angles near mechanical zero have been diminished;8 The automatic seeking into optical zeroes of polarizer and analyzer is realized with the angle error less than 0.025° ;9 The proposition of "Iterative Computing with Ransacking Power" processes the ellipsometric parameters with high precision , speed and stablization;10 A sound testing of the very system shows that the newly designed instrument exerts brilliance in precision and speed;11 A discussion about the reduction of errors is also proceeded in this paper;...