Micro-probing system for coordinate metrology using a particle controlled by optical radiation pressure based on standing wave scale sensing method

Currently, micro-components are required to fabricate with great precision owing to the miniaturization of complex product. In order to assess the dimension, size, and other geometric quantities of such complex micro-components, technological progress is needed in micro- and nano-coordinate metrology. Therefore, the coordinate metrology have been attempted thus far. To establish nano-coordinate metrology with a microprobe technique, we have been developing the optically trapped probe, whose principle is based on the single-beam gradient-force optical trap of a particle in air. However, the rapidly increasing complexity including micro-fine figures makes it difficult to evaluate geometric quantities using a microprobe that can barely access a concave surface. An improved microprobe is required to have a better long working distance, wide measurement range, and high resolution. In this paper, a novel probing technique for coordinate metrology is discussed. The proposed method is based on optical interference, which is seen as a standing wave pattern, also called a standing wave scale. The feasibility is examined by the profile measurement of a smooth surface with high accuracy and the dimensional measurement of a trench structure.