a sulfonic acid group, (3) a corrosion inhibitor, (4) a water› soluble polymeric compound, (5) a pH adjustor, (6) abrasive particles and (7) a surfactant. The second electrolytic liquid may also contain, as a starting component, (8) the same conductive material as the polishing object, e.g., copper. 

[0139] The pH of the second electrolytic liquid for the present process is preferably adjusted to 3 to 6, more preferably 3 to 4.5. An interaction between a polishing object (conductive material), such as copper, in an oxidized state and a corrosion inhibitor, a water-soluble polymeric compound and an organic acid differs depending on the pH of the electrolytic liquid, producing a difference in the quality of a protective film which is formed on the surface of the conductive material, such as copper, during polishing. For example, when a polymeric compound is involved in the formation of a complex between copper and a corrosion inhibitor, such as BTA (benzotriazole ), the protecting effect of BTA is low and the resistance to electrolytic etching is poor at around neutral pH of the electrolytic liquid. On the other hand, a dense strong protective film can be formed when the pH of the second electrolytic liquid is adjusted to 3 to 4.5. 

[0140] As with the above-described electrolytic liquid, the organic acid contained in the second electrolytic liquid for the present process needs to form a soluble complex with a metal (conductive material), such as copper, as a polishing object. In particular, the organic compound needs to make a coordinate bond with a metal, such as copper, to form a complex which is soluble in the aqueous solution. At least the organic acid itself must be water-soluble. As with the above-described electrolytic liquid, the organic acid prefer› ably has at least one carboxyl group (-COOH) in the molecule, or also has at least one hydroxyl group (-OH) together with a carboxyl group(s) in the molecule. The same specific organic acids as mentioned above can be used also for the second electrolytic liquid. 

[0141] Of such usable organic acids, malonic acid, suc› cinic acid, citric acid, glycolic acid, lactic acid and gluconic acid are particularly preferred. 

[0142] The corrosion inhibitor contained in the second electrolytic liquid preferably is a nitrogen-containing het› erocyclic compound and may be one which is known to form a compound with a metal, such as copper, to be processed, and form a protective film on the metal surface, thereby preventing corrosion of the metal. Such a corrosion inhibitor has the effect of preventing excessive etching, thus prevent› ing dishing. 

[0143] Benzotriazole (BTA), which is well known as a corrosion inhibitor for copper, or its derivatives can be preferably used as a corrosion inhibitor in the second electrolytic liquid. Examples of the derivatives include 5-methyl-lH-benzotriazole (tolyltriazole ), 1-hydroxybenzo› triazole, 4-hydroxybenzotriazole, 5-chlorobenzotriazole, benzotriazole-5-carboxylic acid, and 5-nitrobenzotriazole. From the viewpoint of effectively inhibiting corrosion of a processing surface and, in addition, obtaining a glossy processed surface with little surface roughening, it is pre› ferred to use benzotriazole or 5-methyl-lH-benzotriazole. 

[0144] Examples of other usable corrosion inhibitors, hav› ing the effect of preventing excessive polishing and thereby preventing dishing after forming a protective film on the 

surfaces of recessed portions of a polishing object, such as copper, and clearing off a conductive material, such as copper, between interconnect portions, may include indole; diazole, triazole or tetrazole derivatives such as 2-ethylimi› dazole, benzimidazole, 2-mercaptobenzimidazole, 3-amino- 1,2,4-triazole, 3-amino-5-methyl-4H-1,2,4-triazole, and 5-amino-lH-tetrazole; thiazole derivatives such as 2-mer› captobenzothiazole, sodium 2-mercaptobenzothiazole, 2-methylbenzothiazole, (2-benzothiazolylthio )acetic acid, 3-(2-benzothiazoly lthio )propionic acid, 2-mercapto-2-thia› zolin, 2-mercaptobenzoxazole, 2-5-dimercapto-l ,3,4-thia› diazole (bismuthiol), 5-methyl-1,3,4-thiadiazole-2-thiol, and 5-amino-1,3,4-thiadiazole-2-thiol; pyridine; phenazine; acridine; l-hydroxypyridine-2-thione; 2-aminopyridine; 2-aminopyrimidine; trithiocyanuric acid; 2-dibutylamino-4, 6-dimercapto-s-triazine; 2-anilino-4,6-dimercapto-s-triaz› ine; 6-aminopurine; 6-thioguanine; thiourea; salicylic acid and its derivatives such as salicylaldehyde and salicylalde› hyde oxime; and hydroxyquinolines such as 8-quinolinol and 2-methyl-8-quinolinol (2-methyl-8-hydroxyquinoline ). These compounds may be used either singly or as a mixture of two or more. 

[0145] These compounds can form a stronger protective film on the surfaces of recessed portions of a polishing object, such as copper, by their adsorption onto the surface of copper or copper oxide or by the formation of a chelate complex or a polymeric complex with copper or copper oxide. 

[0146] The water-soluble polymeric compound contained in the second electrolytic liquid for the present process, together with the corrosion inhibitor, forms a uniform pro› tective film, which effectively prevents excessive etching and flattens a metal surface, such as copper. The viscosity of the electrolytic liquid containing the water-soluble poly› meric compound is high in the vicinity of a metal surface (processing surface), such as copper. A viscous film is formed on recessed portions of fine irregularities present in the metal surface, and the fine irregularities are polished and removed, providing a glossy surface. 

[0147] Examples of preferable polymeric compounds hav› ing the above effect are those compounds as exemplified above with reference to the above-described electrolytic liquid, such as polyacrylic acid and its salts. Preferable molecular weight and concentration of the present water› soluble polymeric compound are also the same as described above. 

[0148] When electrolytic polishing is carried out using an electrolytic liquid containing a corrosion inhibitor but not containing a water-soluble polymeric compound, a protec› tive film, which is strong but not uniform, is formed on a processing surface. If polishing is continued, variation in the processing rate of the processing surface, surface roughen› ing of the processing surface, the formation of pits in the processing surface, etc. are likely to occur. Such drawbacks can be prevented and uniform polishing becomes possible by adding a water-soluble polymeric compound to the electrolytic liquid. Thus, a water-soluble polymeric com› pound has the effect of adjusting the strength of a protective film formed by a corrosion inhibitor and making the pro› tective film uniform. Polishing may therefore be carried out in such a manner that in an initial polishing period, an electrolytic liquid containing a water-soluble polymeric 

