| 摘要 |
<p>PURPOSE: To enhance the position detecting accuracy by so deciding the step difference of the recess or the protrusion of position detecting marks on a board as to fall within a specific range. CONSTITUTION: The wavelength or the central wavelength of the detected light of a monochromatic or standard color near a position detecting mark made of a recess or a protrusion on a board isλ, m is integer of zero or more, and the step difference (h) of the recess or the protrusion is decided to (2m+1)λ/4-0.05λ<=h<=(2m+1)λ/4+0.05λin the position detecting mark. When the board is a semiconductor wafer, in the most initial step of processing the wafer, the mark is formed on the surface. Further, the mark is a plurality of recesses or protrusions periodically arranged in the measuring direction, a plurality of protrusions or protrusions periodically arranged in a direction substantially perpendicular to the measuring direction or the protrusions or the recesses become bandlike. Thus, asymmetric position detecting marks can be enhanced in the detecting accuracy.</p> |
