Abrasive free formulations for chemical mechanical polishing of copper and associated materials and method of using same

Abstract

An abrasive free formulation for chemical mechanical polishing and method for using the formulation for polishing copper and related materials. The abrasive free formulation has a high removal rate on copper and a low removal rate on barrier material. The abrasive free formulation comprises at least an oxidizing agent and an activating agent.

Description

[0001] This application is a divisional of U.S. application Ser. No. 09 / 9535,805, filed on Aug. 23, 2001, now allowed.TECHNICAL FIELD OF THE INVENTION [0002] The present invention relates generally to the chemical mechanical polishing of semiconductor devices systems and methods, and more particularly, to a formulation and method for use in polishing metal films in semiconductor interconnection processes. BACKGROUND OF THE INVENTION [0003] The present invention relates to a polishing formulation for surfaces of a semiconductor wafer, and more particularly, to a polishing formulation and a method for using the polishing formulation to remove and polish metal containing materials layered on semiconductor wafer surfaces. [0004] Semiconductor wafers are used to form integrated circuits. The semiconductor wafer typically includes a substrate, such as silicon, upon which dielectric materials, barrier materials, and metal conductors and interconnects are layered. These different materials ...

AI Technical Summary

Benefits of technology

[0024] The present invention relates to an abrasive free polishing formulation for removing at least a portion of a metal film deposited during a semiconductor-processing step. The present invention eliminates or reduces disadvantages associated with chemical mechanical polishing processes comprising abrasive components and provides an important technical advantage by eliminating the abrasive component of the slurry thereby reducing the cost of ownership to semiconductor manufacturing facilities.

[0025] The present invention is directed to an abrasive-free polishing formulation, which has a high removal rate on copper and a low removal rate on barrier material and a method of polishing a metal containing material using the abrasive free polishing formulation.

[0029] As will become apparent from the discussion that follows, the stable abrasive free formulation and method of using said formulation provide for removal of material and polishing of semiconductor wafer surfaces with significantly no dishing or oxide erosion, with significantly no surface defects and good planarization efficiency, and produce a copper surface with minimal corrosion tendency post-polish.

Problems solved by technology

If left unattended, the elevational disparities in each level of an integrated circuit can lead to various problems.

For example, when dielectric, conductive, or semiconductive material is deposited over a topological surface having elevationally raised and recessed regions, step coverage problems may arise.

Also, stringers or fences may arise from incomplete etching, polishing, or redeposition of metal.

If such selectivity is not maintained, unwanted dishing of copper and / or erosion of the dielectric material may occur.

This disparity in removal rates during the removal and polishing of the barrier material results in significant dishing of copper on the surface of the semiconductor wafer and / or poor removal of the barrier material.

Another problem with conventional CMP slurries is that the removal chemistry of the slurry is compositionally unstable.

Further, many of the colloidal and fumed abrasives agglomerate after relatively short time frames following addition to the supporting chemistry.

Both of these problems lead to significant operational obstacles such as the need for an expensive continuously recirculating distribution system equipped with filtration, chemistry monitoring, chemical addition equipment, and on-line particle monitors.

A further problem in commercial CMP slurries is that the abrasive materials in the slurries produce defects in the form of micro scratches.

The scratches and other defects occur due to the solid abrasive, in particular alumina, which is the main material used as a metal polishing abrasive.

Slurry remains behind in the micro-scratches causing the semiconductor device to fail.

Micro scratches and poor planarization efficiency result in integrated circuits with increased defects and a lower yield.

Still another problem of commercial CMP slurries is that the chemicals that make up the slurries produce a copper surface that has a high corrosion tendency post polish.

A further problem that occurs in commercial CMP relates to the peeling of the metal film surface from the substrate due to frictional force between the polishing abrasive and the metal film surface.

A still further problem that exists for semiconductor manufacturers in commercial CMP is the cost of abrasives, polishing pads, slurry feeders, processor for slurry containing waste and stirrers to prevent sedimentation of the abrasive in the slurry feeder.

Further, since CMP machines are set up in cleanroom environments, the dust generated by the solid abrasive material must be kept to a minimum This requires expensive systems to be installed to suppress dust in the exhaust duct of the CMP machine;

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