| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide method of calculating the center position of a wafer by detecting the outer periphery of the wafer based on image processing so as to prevent the center position of the wafer being erroneously calculated due to false recognition of the outer peripheral position of the wafer. <P>SOLUTION: The wafer center position detection method comprises the steps of detecting four or more position coordinates of periphery edges E1,E2,E3,E4 of a wafer, obtaining all combination of three position coordinates based on values of the detected plural position coordinates of the periphery edges, calculating coordinates of the calculated center positions O<SB POS="POST">1</SB>,O<SB POS="POST">2</SB>,O<SB POS="POST">3</SB>,O<SB POS="POST">4</SB>of each of the combination, calculating variation in the calculated coordinates of the center positions O<SB POS="POST">1</SB>,O<SB POS="POST">2</SB>,O<SB POS="POST">3</SB>,O<SB POS="POST">4</SB>, detecting the position coordinates of the edges again when the variation is greater than a predetermined threshold value based on determination that the edge 52 is erroneously recognized, and determining that the edges are correctly recognized when the calculated variation is equal to or smaller than the predetermined threshold value, so as to prevent the center position of the wafer being erroneously calculated due to false recognition based on image processing. <P>COPYRIGHT: (C)2012,JPO&INPIT |
