Film Thickness Measurement Based On Ellipsometry

This subject mainly aims at the precise measurement of transparent film, and the improvement of the original equipment, making them more intelligent. This dissertation comprehensively and systematically discussed advantages and application of the ellipsometry by describing its generation, development and existing state. The main work of the dissertation can be summarized as following:1. Creating the mathematical model of the polarized light when it went through the POSA ellipsometry by applying Jones Matrix Theory, and deducing the ellipsoid parameterψandâ–³of one time light extinction method measurement, double time light extinction method measurement and quad time light extinction method measurement, laying the theoretical foundation for precise measurement using light extinction method.2. In order to make ellipsometry is more extensive application and measuring more automation, the control system and detection system of the original extinction type - photometric type compatible automatic ellipsometry are improved. The automatic control system and the automatic detection system with C8051F020 MCU core chip are designed and developed.(including driving circuit of step-motor, A/D conversion circuits and computer interface circuits). Then the polarizer, the analyzer, the step rotary ofλ/4 wave plate, signal acquisition and data processing are carried out under the computer control. Thus automated measurement is achieved. And the time measuring four times by light extinction method is less than 2 minutes.3. According to extinction ellipsometry theory, the extinction ellipsometry calculation program are developed which is using Borland C + + Bulider 6.0 software. This program fit all film thickness calculation with different parameters. And theoretical relation curve and data form about parameters are generated. The precision and conveniences of ellipsometry are greatly improved because of the advanced working interface and fast computing speed. Through theoretical analysis and experimental research, the multi-angle incident ellipsometry method of judgement of film thickness cycles is puted forward. ompared to conventional methods, with measurement time is short and high accuracy, thus it further perfected ellipsometry. In the data processing system, designed with advanced Ellipsometry transparent film thickness measurement procedures. Compare with conventional method,this method has advantages ,for example,short measuring time, high accuracy .And this method is further enrich ellipsometry method.4. After a precision ellipsometer for debugging, the BaK₇ substrate K₉ glass waveguide films was tested in experimental study, demarcated through the step device. It prove that the instrument has good reliability and repeatability. The experiments showed that the measurement error of the elliptical polarized film thickness is less than 100 angstroms, which basically meets the requirements of a transparent film thickness measurement.Theoretical and experimental study show that ellipsometry is atechnique accurate, sensitive and non-destructive measurement. The developing direction of the ellipsometer is the fully automatic ellipsometry and IR ellipsometry.