| 摘要 |
PURPOSE:To accomplish both the measure corresponded with the rotation of a wafer and the simple structure with which a multipoint measurement can be performed on a wafer by a method wherein a signal-detecting means, to be used to detect a monitoring signal from the surface of a semiconductor substrate rotating at a constant speed, is provided in synchronization with the period of rotation. CONSTITUTION:The light (a) emitted from an He-Ne laser 3b is formed into a parallel light (a) rectilinearly widened by a one-dimensional beam expander consisting of a cylindrical concave lens 37-1 and a cylindrical convex lens 37-2. This beam of light is made to irradiate in such a manner that it comes in collision with a substrate 35 in the direction where the radial direction of the rotation of a wafer is brought in line with the direction of width of light, and the wide-widthed reflection light C is received by a line sensor 38. When the number of rotation of the substrate 35 is set at 30 rpm, for example, the period of rotation becomes 2 seconds, and the resolution of 2 seconds can be obtained by sampling once in a period of the information at an optional point on the substrate. Pertaining to a multipoint measurement, all points can be obtained at a time in the radial direction, and a monitoring operation is performed by selecting from all points a signal from the picture element having a low degree of influence of the resist.
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