Patent ID: 7241692

Claim:
A method for chemical mechanical polishing of mirror structures, the method comprising: providing a semiconductor substrate; forming a first dielectric layer overlying the semiconductor substrate; forming an aluminum layer overlying the first dielectric layer, the aluminum layer having an upper surface with a predetermined roughness of greater than 20 Angstroms RMS; processing regions overlying the upper surface of the aluminum layer using a touch-up polishing process to reduce a surface roughness of the upper surface of aluminum layer to less than 5 Angstroms to form a mirror surface on the aluminum layer; forming a protective layer overlying the mirror surface on the aluminum layer to prevent defects including particle scratch and scratch, which is caused in one or more of the following processes; patterning the aluminum layer to expose portions of the dielectric layer to form a plurality of pixel regions defined by borders from the exposed portions; forming a second dielectric layer overlying the patterned aluminum layer and exposed portions of the first dielectric layer; and removing a portion of the second dielectric layer to expose the protective layer, whereupon the protective layer acts as a polish stop layer.