| 摘要 |
<p>PURPOSE:To surely convert an image of a wafer into a binary-coded value without being influenced by a surface state of the wafer such as a reflected light and to smoothly process the image by a method wherein an illuminant is placed in a background and a shadow of the wafer is picked up by using a television camera. CONSTITUTION:Images of positioning marks M1, M2 of a transparent cover 23 are picked up by using a television cameral 11; the central position of a wafer holder 22 is found; an instruction to position an xytheta table in the origin for an x-axis, a y-axis and a theta-axis is sent. Then, a wafer 21 is placed on the wafer holder 22; a shadow of the wafer 21 is picked up by using the television camera 11; a displacement from the origin and an angle of rotation are found; an operating instruction is sent to an xytheta table controller 15; a direction and a position of the wafer 21 are decided. When a positioning operation is finished, the shadown of the wafer 21 is picked up again. When the position and an angle error are not within a definite range, a correction signal is sent to the xytheta table controller 15 and a correction operation is executed until they are set withing a preset range. Thereby, it is possible to surely process the image of the wafer 21 without being influenced by a reflection state of the wafer 21.</p> |
