Highly Precise Atomic Force Microscope Measurement of High-Aspect Nanostructure Free of Probe Bending Error

Abstract

A new atomic force microscope (AFM) imaging has been used to study the bending of a sharpened and slim probe in the digital probing method (step-in mode) for the critical dimension (CD)-AFM technique. The bending of the AFM probe indicates a serious problem in measuring very fine patterns with a high aspect ratio with an error of less than 1 nm when we use the sharpened and slim probe. In our estimation, position errors Δr (in plane) and Δz (in perpendicular) rapidly increase with the slope angle and a controlled force. In experiments, we measured a degradation of the pattern profile as the controlled force increased in the AFM system. We have to control the probe at a force of <2 nN to be free of probe bending, when we measure very fine pit patterns with a size of <100 nm and an aspect ratio of >5 accurately.