| 摘要 |
PURPOSE:To augment the contrast of a reflected beam to incident beam and thereby to realize a high-precision masking by a method wherein an alignment mark in a substrate has a wedge-type cross section, one of the two long sides of the wedge runs vertical to the substrate surface, and the apex angle of the wedge is larger or smaller than 45 deg.. CONSTITUTION:An incident beam 3 arriving at a substrate 1 at a right angle experiences two different directions of reflection, one from a marked region and the other from an unmarked region. A reflected beam 4 from an unmarked region bounces back in the direction along which the incident beam 3 came, to be observed as a bright portion. An incident beam 3 reaching a marked region is reflected in a direction quite different from the one it came along. For example, when an apex angle theta is larger than 45 deg., the incident beam 3 bounces back outside a wedge-type positioning mark 1a and, when the apex angle theta is smaller than 45 deg., the incident beam 3 repeatedly bounces toward the apex of the wedge. An apex angle theta of 45 deg. may not be used as a positioning mark because in such a case the incident beam 3 will be reflected by a substrate wall and then again by a slope to travel back in the direction it came from. A reflected beam 4 form a marked region not going back in the direction it came from is observed as a dark portion.
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