Patent ID: 7713879

Claim:
A method of chemical mechanical polishing a substrate of a type comprising: a first stepped portion having a first upper face, a first lower face positioned below the first upper face, and a first sidewall between the first upper face and the first lower face; and a first layer on the substrate, the first layer including a stepped portion, the stepped portion formed over the first stepped portion, the stepped portion substantially conforming to the first stepped portion, the first upper face of the first stepped portion positioned below the first layer, the method comprising: performing a first polishing process on the stepped portion of the first layer using a slurry composition including a surfactant having an anionic polymer to change the first layer into a second layer having a substantially flat surface, the second layer covering the first upper face, the slurry composition having a pH value at which a zeta potential of the first layer is positive; and performing a second polishing process on the second layer until the first upper face of the first stepped portion is exposed.