FORMATION METHOD OF ALIGNMENT MARK

摘要

PROBLEM TO BE SOLVED: To provide a formation method of an alignment mark that can be detected accurately. SOLUTION: An oxide film 12 is formed on the surface of a silicon substrate 11, and an SOI (Si) layer 13 is formed on the surface of the oxide film 12. The SOI layer 13 is oxidized by a LOCOS treatment locally, an element separation layer 14d of a specific pattern, corresponding to a circuit pattern, is formed in an element formation region, and at the same time, an oxide film 14m in a shape corresponding to the mark M is formed at a specific position in a mark region. After that, a resist film is formed for etching on the surfaces of the SOI and element isolation layers 13 and 14d in the element formation region, and the oxide film 14m in the mark region and the oxide film 12 at the lower side are removed, thus forming the mark M which has the depth corresponding to the oxide film 12 and SOI layer 13, and detecting the position of the mark M accurately, by radiating a laser beam or the like.