Research On Random Error Estimation Of Single Rotating Compensator Ellipsometer

With the improvement of hardware and accuracy level,the single rotating compensator ellipsometer has been widely used,which includes the stability of the light source,the polarization modulation motion control,and the sensitivity and signal-to-noise ratio of the detector.The hardware level of the ellipsometer not only affects the accuracy of the instrument measurement,but also affects the repeatability accuracy of the instrument measurement.Even after high-precision calibration,the measurement results still deviate from their true values when using an ellipsometer to measure nano-film samples.The causes of these deviations include instrument random noise,instrument system errors,environmental random noise,and human error factors.Among them,the deviation caused by the random noise of the instrument reflects the uncertainty level of the instrument.Facing the demand of the spectroscopic ellipsometer to output the uncertainty of film thickness and other parameters while measuring,this paper proposes to establish a rapid evaluation method and calculation model for the measurement of random errors for the single rotating compensator ellipsometer,which can realize the purpose of obtaining uncertainty estimates of measured values while measuring.The main contents of this thesis are as follows:(1)A random error evaluation model of a single rotation compensator ellipsometer has been established.According to the measuring principle of the single rotating compensator ellipsometer,the random error of the system has been traced.We proposed and established the light intensity noise model of the random error source of the single rotating compensator ellipsometer,and on this basis,we established its random error transmission and evaluation model.(2)The noise transfer model and random error evaluation model have been verified.According to the noise model and its application method,a corresponding simulation experiment environment has been constructed.In the simulation state,we got the random error of the model calculation and the random error of the simulation experiment.Through comparative analysis,we theoretically verified the applicability of the light intensity noise model and the random error model.(3)Based on the noise model,we collect light intensity noise signals from different instruments and use them as a source of random errors.We have experimentally verified the proposed uncertainty assessment model.The comparison of sub-measurement statistical results verifies the accuracy and applicability of the established error evaluation model.We have done the experimental verification on the error assessment model,and verified the accuracy and applicability of the established error assessment model by comparing with the statistical results of multiple measurements of multiple samples.