Patent ID: 7459798

Claim:
An overlay mark, comprising: a first material layer having a first trench therein serving as a first portion of a trench type outer mark; a first deposition layer partially or incompletely filling the first trench; a second material layer having a second trench therein serving as a second portion of the trench type outer mark, wherein a thickness of the second material layer is smaller than that of the first material layer and the second trench exposes at least a portion of the first deposition layer in the first trench; a second deposition layer partially or incompletely filling the second trench and covering the first deposition layer in the first trench; a third deposition layer covering the second material and the second deposition layer, wherein a step height is formed on third deposition layer between the edge of the first trench and the center of the first trench, because the first trench incompletely fills with the first deposition layer, respectively; and a raised feature made of a patterned photoresist layer on the third deposition layer to serve as an inner mark.