Abstract: Carbon nanotubes can detect information from deep trenches that conventional probes cannot. It provides a good approach to minimize the distortion of the measured profile caused by interaction with the finite probe tip. However, there is nearly always a significant tilt angle resulting when the nanotube is attached to an ordinary probe. As a result, an accurate sidewall image of only one side of the linewidth sample rather than two sides can be obtained. A dual image stitching method is proposed. After the first scanning that provides an accurate profile of one side, the sample is rotated 180°to obtain the second image, which provides an accurate profile of the other side of the line. Keep the sidewall data for the better side of each image and neglect the data for the other side of each image to combine these better two sides to yield a new image which is more close to the real sample. Image registration based on an improved iterative closest point (ICP) method is applied to remove the position difference between these two images. The bilinear interpolation and the least square fitting method are adopted to deal with the images after registration, and then the more accurate feature sizes than ever such as linewidth, sidewall angle, etc. can be calculated.

Key words: AFM, Carbon nanotube, Dual image stitching method, Image registration