Polishing slurry and method of polishing substrate by using the polishing slurry

A method of polishing a substrate, the method comprising:

• preparing a substrate on which a nitride film and an oxide film are formed, the oxide film being formed on a surface of the substrate;
• and
• polishing the oxide film on the surface of the substrate by supplying a polishing slurry to the substrate,
• wherein the polishing slurry includes an abrasive material, a first oxide polishing promoter, a first nitride polishing inhibitor, and a second nitride polishing inhibitor,
• the first oxide polishing promoter includes a polymer-based oxide polishing promoter,
• the first nitride polishing inhibitor includes an anionic nitride polishing inhibitor, and
• the second nitride polishing inhibitor includes at least one selected from a cationic nitride polishing inhibitor and a non-ionic nitride polishing inhibitor.