Method for calibrating ellipsometer with phase compensator

Abstract

The invention discloses a method for calibrating a polarization angle of an ellipsometer with a phase compensator in an ellipsometry system, a phase delay angle of the phase compensator and a light incidence angle of the ellipsometer, and belongs to the technical field of optical measuring instruments. The method is characterized in that correction values of working parameters of the ellipsometer with the phase compensator are obtained by fitting via a least square method according to experimental Fourier coefficients, optical constants and a deduced relational expression among theoretical Fourier coefficients and the working parameters of the ellipsometer. By the method, system parameters including polarization directions of a polarizer and a polarization analyzer, the delay angle of the phase compensator and the light incidence angle of the ellipsometer with the phase compensator can be calibrated, a calibrating process is simple and accurate, the ellipsometer can be directly used for measuring without adjusting components of the system after calibration is completed, accordingly, a measuring process is simplified, and measurement precision is improved.

Description

technical field [0001] The present invention relates to the technical field of optical measuring instruments, in particular to a calibration of the polarization direction, the fast (slow) axis direction of the phase compensator, the delay angle of the phase compensator, and the incident light angle in an ellipsometry system including a phase compensator method. Background technique [0002] With the rapid development of the semiconductor industry, it is very important to use optical measurement technology to accurately measure the critical dimension (Critical Dimension), spatial morphology and material properties of the three-dimensional structure formed by single-layer or multi-layer thin films on the wafer. For the measurement results to be valid, the measurement system used should be able to measure film thickness and / or film composition with high accuracy. At present, the well-known non-destructive detection technology, ellipsometry, obtains the characteristic parameter...

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Problems solved by technology

Because in the above-mentioned calibration method, it is generally necessary to rotate the polarizer P electrically or manually, and after determining the polarization direction of the polarizer, it is also necessary to manually or electrically rotate the polarizer to a certain angle required, the mechanical structure is unstable and or human error will cause the error between the actual angle and the angle that needs to be set, resulting in the inaccuracy of the sample measurement. Therefore, in the prior art, the calibration method of the polarizer angle is relatively low in accuracy. This limits the measurement accuracy of the ellipsometer

[0007] The angle of incidence in the ellipsometer can be obtained by manual measurement, but due to the limited accuracy of manual measurement, and some measurements need to measure the sample at different angles of incidence to obtain more information about the sample, manual measurement is prone to human error Adjustment errors or reading errors lead to errors in data analysis results. Chinese patent application No. 201010137774 discloses a device for automatic detection of incident angles in ellipsometry systems, which can realize automatic detection of incident angles, but this device needs to be The installation of position detection devices in multiple places in the system will lead to a complex structure of the ellipsometer system, and the position calibration of the position detection device is also a relatively complicated process, which limits the application of the automatic detection device in the ellipsometer

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