| 摘要 |
PURPOSE:To place a circular substrate always in a constant state (in positional accuracy) with respect to the placing surface by providing positioning means having a reference member so composed as not to cause the positional displacement (center displacement) of the substrate out of two-dimensional moving stage. CONSTITUTION:In case of positioning 0 deg., rollers 12a, 12b are disposed at a distance corresponding to the length of a vertical line suspended from the center of a wafer W to a flat F from the rotating center of a turntable 1, and a roller 16c is so determined as to be positioned at a distance corresponding to the length of the radius of the wafer W from the rotating center of the table 1. In case of 90 deg., it is similarly disposed. Thus, in case of both 0 deg. and 90 deg., the center O of the wafer W accurately coincides with that O1 of the placing surface at the stage of placing it on a wafer holder 4. |
