Large step structure measurement by using white light interferometry based on adaptive scanning

摘要

As an important measuring technique, white light scanning interferometry can realize non-contact, fast and high accurate measurement. However, when measuring the large step structure, the white light scanning interferometry has the problems of long time consumption and low signal utilization. In this paper, a kind of adaptive scanning technique is proposed to measure the large step structure to improve its efficiency. This technique can be realized in two ways-the pre-configuration mode and the auto-focusing mode. During the scanning process, the image collection is limited within the coherence area, and in other positions, the motion is speeded up. The adaptive scanning is driven by the nano-measuring machine (NMM) which reaches nanometer accuracy and is controlled by the measurement software. The testing result of lOOum step height shows that the adaptive scanning can improve the measuring efficiency dramatically compared with conventional fixed-step scanning and it keeps the same high accuracy.