| 摘要 |
<p>PURPOSE: To make a position detection error small even if a mark is asymmetric at the time of detecting the position of the mark by detecting diffraction light rays from the uneven mark on a substrate of a wafer. CONSTITUTION: The width of an asymmetric bottom part (a recessed part) 25a of a wafer mark 25 in the detection direction is set to be 1/m (m is integer not less than 2) of the pitch P of the wafer mark 25. Luminous fluxes L from a laser light source 21 are radiated to the wafer mark 25 and only±m-order diffracted light rays Lm, Lp from the wafer mark 25 are extracted by a spatial filter 23A and the extracted diffracted light rays are converged on a reference grating 26 to form interference fringes and luminous fluxes Ld which pass the reference grating 26 are received by a photoelectric sensor 27.</p> |
