Polishing fluid and polishing method

Abstract

The present invention relates to polishing slurry and polishing method used for polishing in a process for forming wirings of a semiconductor device, and the like. There are provided polishing slurry giving a polished surface having high flatness even if the polished surface is made of two or more substances, and further, capable of suppressing metal residue and scratches after polishing, and a method of chemical mechanical polishing using this. The polishing slurry of the present invention is polishing slurry containing at least one of a surfactant and an organic solvent, and a metal oxide dissolving agent and water, or polishing slurry containing water and abrasive of which surface has been modified with an alkyl group, and preferably, it further contains a metal oxidizer, water-soluble polymer, and metal inhibitor.

Description

FIELD OF THE INVENTION The present invention relates to polishing slurry and a polishing method used for polishing in a process of forming wiring of a semiconductor device, and the like. BACKGROUND TECHNOLOGY Recently, novel fine processing technologies are being developed with increase in the degree of integration and the performance of semiconductor integration circuits (hereinafter, referred to as LSI). Also a chemical mechanical polishing (hereinafter, referred to as CMP) method is one of these technologies, and is a technology frequently used in flattening of an interlayer insulating film, formation of a metal plug and formation of implanted wiring in an LSI production process, particularly, a multi-layer wiring formation process. This technology is disclosed, for example, in U.S. Pat. No. 4,944,836. Recently, for increasing the performance of LSI, utilization of copper and copper alloy has been tried as a conductive substance of a wiring material. However, it is difficult t...

AI Technical Summary

Benefits of technology

As the abrasive in the present invention, any of inorganic particles of silica, alumina, zirconia, ceria, titania, germania, silicon carbide and the like and organic particles of polystyrene, polyacryl, polyvinyl chloride and the like may be used. Of them, silica, alumina, zirconia, ceria, titania and germania are preferable, and particularly, colloidal silica and colloidal alumina showing excellent dispersion stability in polishing slurry, producing a small number of generation of polishing flaws (scratches) generated by CMP, and having an average particle size of 70 nm or less are preferable, and colloidal silica and colloidal alumina having an average particle size of 40 nm or less are more preferable. The particle size can be measured, for example, by an optical diffraction scattering type particle size distribution meter (for example, COULTER N4 SD manufactured by COULTER Electronics). Particles obtained by coagulation of less than 2 on average of primary particles are preferable, and particles obtained by coagulation of less than 1.2 on average of primary particles are more preferable. Further, the standard deviation of average particle size distribution is preferably 10 nm or less, and the standard deviation of average particle size distribution is more preferably 5 nm or less. These can be used singly or in combination of two or more.

The barrier layer is formed to prevent of diffusion of a conductive substance in an insulating film, and to improve close adherence of an insulating film and a conductive substance. It is preferable that a conductor used in a barrier layer contains one or more selected from tungsten, tungsten nitride, tungsten alloy, other tungsten compounds, titanium, titanium nitride, titanium alloy, other titanium compounds, tantalum, tantalum nitride, tantalum alloy and other tantalum compounds. The barrier layer may be a single layer composed of one compound or a laminated film composed of two or more compounds.

Problems solved by technology

However, it is difficult to finely process copper and copper alloy by a conventional dry etching method frequently used in formation of aluminum alloy wiring.

Consequently, a phenomenon of formation of depression in the form of dish at the central portion of the surface of implanted metal wiring after polishing (hereinafter, referred to as dishing) occurs, deteriorating the flattening effect.

However, the conductor of this barrier layer has high hardness as compared with copper or copper alloy, consequently, sufficient polishing speed is not obtained and its flattening property deteriorates in may cases even if a polishing material for copper or copper alloy is combined.

For increasing the polishing speed of an interlayer insulating film corresponding to the polishing speed of a barrier layer and metal for wiring part, there is envisaged, for example, to increase the size of abrasives in polishing slurry for conductor of a barrier layer, however, there is a problem that scratch occurring on copper or copper alloy and an oxide film, causing a poor electric property.

Such a poor electric property is generated also by poor washing after polishing by CMP.

On the other hand, there is a problem of occurrence of a short-cut defect since the copper residue on high density wiring parts cannot be removed in a CMP process.