| 摘要 |
PURPOSE:To achieve a highly accurate measurement of a distance between two parallel plates by measuring the quantity of light emitted from one of two separate light transmitting sections provided on one plate is such a manner that a light entering from the other light transmitting section is emitted from said one after being reflected on the other plate. CONSTITUTION:For example, an X ray mask 28 made of a polyimide film 19 having an element pattern 21 and a pattern (gold film) 22 for a light transmitting section is arranged parallel to a silicon wafer 23 fixed on a table 26. An Al film 24 and a PMMA resist 25 is applied on the wafer 23. A light beam of a He-Ne laser light source 27 enters the X ray mask 28 at a certain angle. Passing through one window at the light transmitting section 22, it is reflected on the wafer 23 and emitted through the other window. The quantity of the light is detected with a photo detector 29, thereby enabling a highly accurate determination of the space between the wafer 23 and the mask 28 from the space between the two windows. |
