US Patent 11640118 Method of pattern alignment for field stitching

A method of pattern alignment is provided. The method includes identifying a reference pattern positioned below a working surface of a wafer. The wafer is exposed to a first pattern of actinic radiation. The first pattern is a first component of a composite pattern. The first pattern of actinic radiation is aligned using the reference pattern. The wafer is exposed to a second pattern of actinic radiation. The second pattern is a second component of the composite pattern and exposed adjacent to the first pattern. The second pattern of actinic radiation is aligned with the first pattern of actinic radiation using the reference pattern.