Measurement of deep groove structures using a self-fabricated long tip in a large range metrological atomic force microscope

Abstract

Metrological atomic force microscopes are widely used in national metrology institutes for measuring step height, lateral pitch and surface roughness. However, the maximum measurable depth or height variation is limited by both the vertical scanning range of the AFM and the tip height and sharpness of the tip at the end of the cantilever. A normal commercial AFM typically has a vertical scanning range less than 10 µm and a tip height of the cantilever only up to 15 µm so that it can be used to detect only relatively smooth surfaces or shallow structures up to several micrometres. To overcome these limitations, we have successfully integrated a long diamond tip of up to 120 µm developed at Namiki Precision Jewel Co., Ltd of Japan onto our large range metrological atomic force microprobe (LRM-AFM) for deep groove structure measurement. The LRM-AFM is based on a nano-measuring machine with a large scanning range of 25 mm in the X and Y axes and 5 mm in the Z axis. This paper describes the long diamond tip fabrication process and especially its application in the LRM-AFM for measuring deep groove structures of a step height of up to 100 µm. In addition, the mechanical quality factor (Q) of the diamond tip micro-cantilever was detected in the system. The results demonstrate that the system is capable of calibrating and measuring the surface structure with deep groove in tens of micrometres.