Polishing liquid

A polishing method comprising polishing a barrier metal material on an interlayer insulation material, the polishing using a polishing liquid, wherein the polishing liquid has a pH of from 2.0 to 6.0 and comprises

• an aqueous solution containing a compound represented by the following formula (1), the content of the compound in the polishing liquid being from 0.0005 to 3 mol/L,
• polishing particles containing silicon oxide and dispersed in the aqueous solution, the content of the polishing particles in the polishing liquid being from 0.01 to 20% by mass, and
• a heterocyclic compound selected from the group consisting of 1,2,3,4-tetrazole, 5-amino-1,2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 1,2,3-triazole, 4-amino-1,2,3-triazole, 4,5-diamino-1,2,3-triazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3,5-diamino-1,2,4-triazole and benzotriazole, the content of the heterocyclic compound in the polishing liquid being from 0.01 to 0.10% by mass:
• R1—(CH2)m—(CHR2)n—COOH (1)
• wherein 1≦m+n≦4;
• R1 represents a hydrogen atom, a methyl group, an ethyl group or a hydroxyl group;
• R2 represents a methyl group, an ethyl group, a benzene ring or a hydroxyl group;
• and when a plurality of R2s are present in the formula (1), they are the same or different from one another;
• wherein the electric conductivity of the polishing liquid is from 0.2 to 8.0 mS/cm.