Patent ID: 7737426
Filing Date: 2010-06-15
Classification: H01L

Abstract:
1. A substrate positioning device which positions a substrate having a two-layer structure, the two-layer structure includes a transparent layer with a high level of light transmissivity and a nontransparent layer with a low level of light transmissivity having smaller external dimensions than said transparent layer, the transparent layer and the nontransparent layer are superposed one on top of the other so that an edge of said transparent layer extends along an entire periphery beyond an edge of said nontransparent layer, comprising: a stage on which said substrate is placed; a light emitting means for emitting light toward said substrate on said stage by directing the light toward the edge of said substrate including the edge of said transparent layer and the edge of said nontransparent layer; a light-receiving means disposed to face opposite said light emitting means with said substrate set in between, which includes a plurality of light-receiving pixels linearly arrayed from a point further outside relative to the edge of said substrate toward a point further inside relative to the edge of said substrate and outputs signals each corresponding to the intensity of light received at one of said light-receiving pixels; and a control unit that compares the signals output from said light-receiving means with a preset threshold value to determine whether the output signal from each light-receiving pixel indicates a light transmission level or a light blocking level, then detects a boundary at which a changeover from said light transmission level to said light blocking level occurs along a forward direction in the array of the sequentially disposed light-receiving pixels as the edge position of said nontransparent layer only if said light blocking level following said changeover is judged to be sustained over a number of light-receiving pixels equal to or greater than a distance between the edge of said transparent layer and the edge of said nontransparent layer, wherein only the edge position of said nontransparent layer over the entire periphery of said substrate, not the edge of said transparent layer, is exclusively detected and said substrate is positioned based upon the edge that is detected.