パターン投影方式小径穴測定装置の性能向上(第1報)

平行平板試料の場合の理論解析

抄録

In this paper, the relationships between the accuracy of measurement of an inner diameter and numerical aperture of a lens, the width of a parallel specimen gap, the z-direction displacement of a specimen and the degree of defocus of a detection lens are discussed theoretically using the noncontact equipment used to measure the diameter of small holes. The method for recognizing the position of the hole's wall involves the detection of an image of a small spot which is projected into a small hole and reflected on the wall. The results of theoretical analysis are as follows. The calculated position of the wall shifts toward the minus direction so the calculated inner diameter is small compared with the true value. The amount of shift in the middle of the specimen is smaller than that in the inlet or outlet of the specimen. The amount of shift depends on the degree of defocus of the detection lens. Therefore, the amount of shift can be adjusted by defocusing the detection lens.