Si/SiO_(2)多层膜线宽关键参数精细化表征技术研究

Research on fine characterization technology of key parameters of line width of Si/SiO_(2) multilayer film

线边缘粗糙度(LER)和线宽粗糙度(LWR)是衡量线宽标准样片质量的重要指标。文中基于自溯源光栅标准物质的自溯源、高精密尺寸结构特性,提出了一种直接溯源型精确校准SEM放大倍率的方法,以实现SEM对线宽标准样片关键参数的测量与表征。利用校准后的SEM,对利用Si/SiO_(2)多层膜沉积技术制备的线宽名义值为500、200、100 nm样片进行关键参数的测量,采用幅值量化参数的均方根粗糙度RMS描述线边缘粗糙度与线宽粗糙度,并通过图像处理技术确定线边缘位置,对线宽边缘特性进行了精确表征。实验结果表明,名义值为500、200、100 nm对的线宽样片,其实测值分别为459.5、191.0、99.5 nm,σLER分别为2.70、2.35、2.30 nm,σLWR分别为3.90、3.30、2.80 nm,说明了多层膜线宽标准样片线边缘较为平整、线宽变化小、具有良好的均匀性与一致性。基于自溯源标准物质校准SEM的方法缩短了溯源链,提高了SEM的测量精度,实现了线宽及其边缘特性的精确表征,为高精度纳米尺度测量和微电子制造领域提供了计量支持。

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 selftraceable 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/SiO_(2) 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.