Detecting method of pattern

Abstract

Abstract PURPOSE:To reduce the noise caused by the regular reflection of an illumination light and thus to obtain a high S/N, by intercepting a polarized-light component in the same direction with that of polarization of bright-field illumination, by extracting only a polarized-light component in the direction perpendicular to that of the polarization of the bright-field illumination, and by detecting the pattern thereof by means of an image sensor. CONSTITUTION:A polarized light (f) is applied on a pattern 1 and a base material 2 through a half mirror 6 and an object lens 3. When an incident light (h) and a reflected light (i) are reflected regularly on the occasion, the directions (j) and (k) of polarization of the incident light (h) and the reflected light (i) become identical, and the reflected light (i) is intercepted by a polarizing plate 8. Accordingly, the noise caused by a luminescent spot on the pattern 1 disappears. When there is a diffused reflection as in the case of an incident light l and a reflected light (m), the direction (n) of polarization of the reflected light (m) is varied with respect to the direction (k) of polarization of the incident light l. Therefore, only a component in the direction of polarization perpendicular to the direction (k) of polarization of the incident light l passes through the polarizing plate 8 as a polarized light (g). Quite the same phenomenon with that described above occurs also in the case of lights falling on and reflected from the base material 2. According to this constitution, the noise caused by the luminescent spot formed by the regular reflection is reduced, a high S/N ratio can be obtained, and thus the accuracy in detection is sharply improved.

Inventors

• 👤 Hiroya Saitou
• 👤 啓谷 斉藤
• 👤 Yasuo Nakagawa
• 👤 中川　泰夫
• 👤 Yoshimasa Oshima
• 👤 良正 大島
• 👤 Takanori Ninomiya
• 👤 隆典 二宮

Bibliographic Details