Patent attributes
A method of forming an overlay mark is provided. A first material layer is formed on a substrate, and then a first trench serving as a trench type outer mark is formed in the first material layer. The first trench is partially filled with the first deposition layer. A second material is formed over the first trench and the first deposition layer. A second trench is formed exposing the first deposition layer within the first trench. The second trench is partially filled with a second deposition layer forming a third trench. A third material layer is formed on the substrate to cover the second deposition layer and the second material layer. A step height is formed on the third deposition layer between the edge of the first trench and the center of the first trench. A raised feature serving as an inner mark is formed on the third deposition layer.
