Method for forming alignment mark

摘要

A method for forming an alignment mark includes defining a circuit pattern area and an alignment mark area on a semiconductor substrate, forming a first pattern in the alignment mark area, forming a second pattern of a first material on the first pattern, forming a layer of a second material different from the first on the entire surface of the semiconductor substrate, and polishing the layer of the second material and the second layer such that the second pattern and the layer of second material are polished at different speed, until a step difference appears between the second pattern and the layer.