A method for forming an alignment mark structure for a semiconductor device includes forming an alignment recess at a selected level of the semiconductor device substrate. A first metal layer is formed over the selected substrate level and within the alignment recess, wherein the alignment recess is formed at a depth such that the first metal layer only partially fills the alignment recess. A second metal layer is formed over the first metal layer such that the alignment recess is completely filled. The second metal layer and the first metal layer are then planarized down to the selected substrate level, thereby creating a sacrificial plug of the second layer material within the alignment recess. The sacrificial plug is removed in a manner so as not to substantially roughen the planarized surface at the selected substrate level.
In a method to produce an alignment mark, an oxide layer and sacrificial layer are processed to comprise recesses. The recesses are filled with a filler material. During filling the recesses, a layer of filler material is formed on the sacrificial layer. The layer of filler material is removed by chemical mechanical polishing. The sacrificial layer protects the oxide layer during filling the recesses and removing the layer of filler material. The sacrificial layer is then removed by etching. This provides an unscratched oxide layer with protrusions. The oxide layer with protrusions is covered with a conducting layer whereby the protrusions punch through the oxide layer to form related protrusions. The related protrusions form an alignment mark.
