基于原子力显微镜的线宽粗糙度测量

李洪波 赵学增
哈尔滨工业大学机电工程学院,哈尔滨150001
摘　要:给出采用原子力显微镜（Atomic force microscope,AFM）测量线宽粗糙度（Line width roughness,LWR）的分析步骤。分析线宽和LWR及其偏差随刻线横截面位置的高度变化的关系,线宽及其偏差和LWR及其偏差随刻线横截面位置的高度值增加而减小。分别采用四种边缘提取算子提取了碳纳米管针尖AFM测量的刻线顶部线宽边缘,计算了刻线顶部线宽和LWR,顶部线宽和LWR测量结果对边缘提取算子不敏感。结合被测单晶硅台阶的顶表面和底表面加工方法,提出采用各扫描线轮廓高度相等的方法校正AFM压电驱动器的z向非线性。比较了采用普通氮化硅探针针尖、超尖针尖以及碳纳米管针尖AFM测量名义线宽为1000 nm刻线LWR的结果,显示采用三种针尖的LWR测量结果存在差异,但考虑到AFM分辨率,可认为测量结果基本相同。因此,为更精确描述刻线边缘,必须提高AFM分辨率。[著者文摘]
Measurement of Line Width Roughness by Using Atomic Force MicroscopeLI Hongbo, ZHAO Xuezeng School of Mechanical and Electrical Engineering, Harbin Institute of Technology, Harbin 150001Abstract:The analytical procedures are illustrated of the measurement of line width roughness （LWR） by using atomic force microscope （AFM）. The relations are presented of line-width, line-width error vs. the height. With the increase of the height, the line width and its error become smaller. The trend of LWR and its error vs. height is the same as that of line-width vs. height. The four operators, i.e., Roberts, Sobel, Canny and Prewitt are respectively used to detect the edges on the top surface measured by using AFM with the carbon nanotube tip. Then the line width and LWR on the top-surface are calculated, which shows that different operators have almost no effect on the line width and LWR. A method to verify the nonlinear in z direction of the piezoelectric actuator of AFM is brought forward in terms of the processing technology on the top and bottom surface of the measured single crystal silicon step. In the method, the height of the scanning profile is equal to one another. LWR is compared with one another which are measured respectively by using AFM with the ordinary tip, the ultra-sharp tip and the carbon nanotube tip. There is no remarkable difference about the step in 1 000 nm nominal line width. Thus the resolution of AFM must be improved in order to get more accurate topography of sidewall.[著者文摘]

Key words:Nano-measurement Line-width roughness （LWR） Atomic force microscope （AFM） Nonlinearity of the piezoelectric actuator Tip