Generalized Elipsometry Measurement System With Variable Angle Driven By Single Motor

With the continuous development of modern information technology,semiconductor integrated circuits,optoelectronics,MEMS sensors,precision optical components,micro-nano materials and so on are widely used in all kinds of photoelectric equipment.Because the performance and reliability of electronic components and optical components will directly affect the comprehensive performance of photoelectric equipment,and all kinds of optical components in the production process usually need to be a variety of materials of film deposition,and the measurement of the film’s physical properties(such as film thickness,refractive index,extinction coefficient,etc.)is the key to ensure the processing quality and performance.The generalized ellipsometer can not only measure the physical properties of thin films,but also detect the structural properties of thin films(such as the thickness of the surface interface film,the proportion of multi-component material alloy,doping concentration,etc.).It is a non-contact,non-destructive,high-precision optical measuring instrument,which has been widely used.At present,the angle variation of the general ellipsometer is realized by two motors,that is,two motors control the offset arm and the sample platform respectively to measure the Angle variation.This kind of dual-drive variable angle has some problems such as complex structure,cumbersome control,expensive price,and deviation of optical path after the variable angle,which does not meet the requirements of integrated instrument,easy operation and low cost.Based on this,this paper intends to carry out a study on a generalized ellipsometry measurement system with variable angle driven by a single motor.The main research work is as follows:First of all,according to the principle of ellipsometry measurement,the variable Angle ellipsometry system driven by a single motor is designed as a whole.At the same time,an "air-Si O2-thin film-Si base system" is established to investigate the impact of incident Angle on the ellipsometry parameters.It is obtained that the accuracy of the ellipsometry measurement results is the highest when the incident Angle is near Brewster Angle.First of all,according to the principle of ellipsometry measurement,the variable Angle ellipsometry system driven by a single motor is designed as a whole.At the same time,an "air-Si O2-thin film-Si base system" is established to investigate the impact of incident Angle on the ellipsometry parameters.It is obtained that the accuracy of the ellipsometry measurement results is the highest when the incident Angle is near Brewster Angle.Secondly,the structure of variable Angle driven by a single motor is designed,and two variable Angle structures,"belt type" and "gear type",are proposed.The structure adopts a fixed deflector arm,and uses a single motor driven by a synchronous gear to make the load platform and the deflector arm rotate synchronously,so as to realize the multi-angle measurement of the ellipsometer.Based on the traditional angular variable structure of the generalized ellipsoid with horizontal structure,a 1:2 synchronous transmission of the sample loading platform and the bias measuring arm was set up,and the feasibility of the proposed structure was verified by Inventor simulation.Finally,the generalized ellipsometry system driven by a single motor is constructed and its drive control is completed.The initial optical path calibration of the generalized ellipsometry system driven by a single motor is completed by calibrating the polarizer and compensator.The air(transmitted type)and standard Si O2-Si thin film samples(reflected type)are measured by the variable Angle generalized ellipsometer system driven by a single motor.The full Muller matrix of the sample is obtained by the variation of the sample light intensity within the obtained optical period.The maximum error of the air Muller matrix element is 0.017,and the average error is 0.0045.The ellipsometric parameter of the standard Si O2 film is 44.2°,the δψis 78.48°,the thickness is 103.8 nm,and the standard deviation is0.2 nm.In this paper,the variable angle structure driven by a single motor not only maintains the collimation before and after the variable Angle,but also has a higher integrated structure,simpler operation and lower cost.It has important academic significance and application value in the engineering process of generalized ellipsometer.