Measuring Research Of Gap Space Between Plate Glasses Based On Ellipsometry

With the development of technology as MEMS and microelectronic manufacture,people set higher standards than ever for the machining accuracy which requests high-precision measurement technique in nanoscale.Among the applied techniques,ellipsometry has the merits including high precision,high sensitivity,and non-contact measurement,therefore,it is wildly used in research fields,for example,photoelectricity,material science,and biotechnology.This thesis puts forward a method to measure the gap space between two plate glasses in nanoscale based on ellipsometry.Firstly,using the method of photometry,by fixing the polarization direction of polaroid and the placement of 1/4 wave plate's fast and slow axis,to calculate the measurand using the signal intensity of laser collected by detector,and analyze the accuracy and feasibility of this method on the basis of the simulation data which is obtained by the algorithm written on MATLAB.Secondly,deducing the functional relationship between the measurand and the polarization direction of polarizer and analyzer when the signal intensity of light collected by detector is 0.Conduct the numerical simulation on MATLAB,and comparing the data which is obtained by changing light's incident angel to determine the the best incident angle.Analyzing the simulation data to find out the request for the angel measurement to make sure the accuracy of measurand using light extinction method,and come up with the way to decrease the impact caused by the angel measurement error to the measuring results.Then using the improved light extinction method by rotating the 1/4 wave plate and the analyzer to detect the polarization of light in any pattern.deducing the formula,using the angel of the analyzer's polarization direction and the placement of 1/4 wave plate's fast and slow axis to calculate the measurand under the condition when the light collected by the detector is extincted.Finally,setting up the experimental platform to verify the simulation data obtained by using light extinction method.Considering the difference between simulation data and experimental data,analyzing the error sources in the experimental process.The conclusion based on both the simulation data and the experimental data shows that the using of the light extinction method of ellipsometry for measuring the gap space between two plate glasses can reach the accuracy of 10nm and the range of 350nm with the instrument which can meet the request of angel measurement accuracy,when light's incident angel is 60°.