Method of forming a marker, substrate having a marker and device manufacturing method

摘要

A marker, for example an alignment marker or an overlay marker is formed in two steps. First, a pattern of two chemically distinct feature types having a pitch comparable to product features is formed. This pattern is then masked by resist in the form of the desired marker, which has a larger pitch than the pattern. Finally, one of the two feature types is selectively etched in the open areas. The result is a marker with a large pitch suitable to be read with long wavelength radiation but the edges of the features are defined in an exposure step having a pitch comparable to the product features.