Polishing composition and polishing method using the same

A method for polishing an object, the method comprising:

• preparing a polishing composition including:
• an abrasive containing a silicon oxide;
• at least one acid selected from the group consisting of orthophosphoric acid, diphosphoric acid, polyphosphoric acid, metaphosphoric acid, hexametaphosphoric acid, methyl acid phosphate, ethyl acid phosphate, ethyl glycol acid phosphate, isopropyl acid phosphate, phytic acid, and 1-hydroxyethylidene-1,1-diphosphonic acid;
• at least one salt selected from the group consisting of sodium salt, potassium salt, and lithium salt of an acid selected from orthophosphoric acid, diphosphoric acid, polyphosphoric acid, metaphosphoric acid, hexametaphosphoric acid, methyl acid phosphate, ethyl acid phosphate, ethyl glycol acid phosphate, isopropyl acid phosphate, phytic acid, and 1-hydroxyethylidene-1,1-diphosphonic acid;
• an oxidizing agent;
• and
• water;
• and
• polishing the object using the prepared polishing composition.