Method and apparatus for determining the position of a target structure on a substrate, and method and apparatus for determining the position of a substrate

摘要

Since the target structure (402) such as the alignment mark on the semiconductor substrate (400) is obscured by the opaque layer (408), the position cannot be specified by the alignment sensor (AS). The position of the mark is determined using an edge position sensor (412), and relative position information defining the position of the mark relative to one or more edge portions of the substrate is stored prior to formation of the opaque layer. Based on the determined position, a window (410) can be opened in the opaque layer. After revealing the target structure, the alignment sensor can more accurately measure the position of the target structure for use in controlling further lithography steps, if desired. The edge position sensor may be a camera having angle selective behavior. The edge position sensor may be integrated within the alignment sensor hardware. [Selection] Figure 4