Abstract:
Objective As the key parameters of line width, line edge roughness (LER) and line width roughness (LWR) are important indicators of the quality of line width standard samples. The accuracy of LER and LWR is important for characterizing the reliability and uniformity of line width standard materials. Inspection is very important. Through the measurement and characterization of LER and LWR, the quality label technology level of line width standard samples can be effectively evaluated. Due to the problem of magnification in the measurement method of SEM, the measurement and characterization of LER and LWR have trays. Therefore, before using SEM to measure the line width, it is necessary to adjust the magnification of SEM with standard substances in advance.
Methods With the self-traceable grating reference material as the standard of mass transmission (Fig.2), SEM is used to scan the self-traceable grating reference material, and the grating period measurement value of the self-traceable grating is obtained (Fig.3). It is compared with the actual grating period value, and the SEM calibration factor is obtained to realize the direct traceability and magnification calibration of the scanning electron microscope. The calibrated SEM is used to measure the different values of the multilayer film line width standard samples in different areas and different magnifications. The image processing technology is used to determine the position of the line edge and the average line edge based on the least squares fitting method. The root mean square roughness of the amplitude quantization parameter is calculated for LER and LWR (Fig.4).
Results and Discussions The calibration of different magnifications of SEM is realized, and the calibration factors under different magnifications are obtained, which ensures the accuracy and traceability of the measurement results and shortens the traceability chain. The measurement results of line widths of different sizes are basically the same at different positions and different magnifications (Tab.2, Fig.8), the fluctuation range of line edge roughness is relatively small, the measured values are relatively consistent, and the change of line width is small (Tab.3, Fig.9); It shows that the edge of the line width sample is relatively smooth, the line width distribution is relatively uniform, and has good uniformity and consistency, which shows that the Si/SiO2 multilayer film deposition technology has the advantages in controlling the line width size and edge characteristics.
Conclusions The SEM value traceability and magnification calibration method based on the self-traceable grating standard material shortens the traceability chain, reduces the traceability error introduced in the process of value traceability, improves the accuracy and reliability of SEM measurement, and provides a possibility for the flattening of the value transfer gradually. Through the measurement and analysis of line edge roughness and line width roughness, accurate characterization of line width and edge characteristics is achieved, and metrological support is provided for high-precision nanoscale measurement and microelectronics manufacturing fields.
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