CHEMICAL MECHANICAL POLISHING METHOD

A planarization method includes: providing a substrate, wherein the substrate includes a first region and a second region having different degrees of hydrophobicity or hydrophilicity, the second region covering an upper surface of the first region; polishing the substrate with a polishing slurry until the upper surface of the first region is exposed; and continuing polishing and performing a surface treatment by the polishing slurry to adjust the degree of hydrophobicity or hydrophilicity of at least one of the first region and the second region. The polishing slurry and the upper surface of the second region have a first contact angle, and the polishing slurry and the upper surface of the first region have a second contact angle. The surface treatment keeps a contact angle difference between the first contact angle and the second contact angle being equal to or less than 30 degrees during the polishing.