Methods of post chemical mechanical polishing and wafer cleaning using amidoxime compositions

Abstract

The invention relates to a method for the removal of residues and contaminants from metal or dielectric surfaces and to a method for chemical mechanical polishing of a copper or aluminum surface. The methods of the invention include using an aqueous amidoxime complex agent. Optionally, the pH of the solution can be adjusted with an acid or base. The method includes applying the above composition to the copper or aluminum surface and polishing the surface in the presence of the composition.

Description

CROSS-REFERENCE TO ELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application No. 61 / 000,727, filed Oct. 29, 2007, and U.S. Provisional Application No. 61 / 006,225, filed Dec. 31, 2007, both of which are incorporated herein by reference in their entirety.BACKGROUND OF THE INVENTION[0002]The present invention relates to compositions and methods for removal of chemical residues from metal or dielectric surfaces or for chemical mechanical polishing of a copper or aluminum surface including an aqueous solution comprising an amidoxime complex applied for a time sufficient to remove the chemical residues.[0003]The National Technology Roadmap for the Semiconductor Industries (1994) indicated that the current computer chips with 0.35 micron feature sizes will be reduced to 0.18 micron feature size in 2001. The DRAM chip will have a memory of 1 gigabit, and typical CPU will have 13 million transistors per cm2 (currently they only contain about 4 million). The...

AI Technical Summary

Benefits of technology

[0018]The present invention provides a method of solving one or more of the following problems common with prior art compositions and methods: reducing or eliminating corrosion problems; eliminating substantial use of flammable solvents; eliminating SARA Title III chemistries; and lowering mobile and transition metal ions.

[0023]In another embodiment, the invention relates to a method for chemical mechanical polishing of a copper surface by applying an aqueous composition having a pH between about 3.7 and about 7 to the copper surface, and polishing the surface in the presence of the composition. Surprisingly, the formulations of the present invention are effective in both an acidic and basic pH range, allowing for customization of the pH based on the needs of the application, not on the effectiveness of the CMP or post-CMP cleaning compositions.

[0032]In another alternative or additional embodiment, the aqueous composition can include an oxidizing agent that will maintain metal film oxide layers. In a preferred embodiment, the oxidizing agent includes ammonium peroxydisulfate, peracetic acid, urea hydroperoxide, sodium percarbonate or sodium perborate. The cleaning agents of the current invention are also chelating agents. The cleaning action of the current invention efficiently removes residual particles from the surface of the semiconductor work-piece and also complexes the metal that is removed in solution. Thus the cleaning efficiency is improved by presenting metal from re-depositing on the semiconductor work-piece surface.

[0033]The corrosion-inhibiting compound of the current invention protects the metal of the semiconductor work-piece from oxidation, and corrosion. The corrosion-inhibiting compounds are effective at forming a film on the metal of the semiconductor work-piece that protects metal surfaces from chemical, galvanic and photo-induced attack during and after the cleaning step. One preferred embodiment forms a protective film by reducing the surface of the metal. By protecting the metal surface from attack, the metal retains its desired thickness and electrical carrying capacity. The cleaning solution of the current invention is not highly sensitive to oxygen because it does not contain any oxygen sensitive compounds. Because the cleaning solution is not highly sensitive to oxygen the performance of the cleaning solution is not affected by the presence of air in the cleaning equipment. Thus, the cleaning solution of the current invention can be used without extra precautions to purge the storage, transfer and cleaning equipment of essentially all air.

[0034]The cleaning solution of the current invention cleans the semiconductor work-piece and forms a corrosion-inhibiting film on the metal surfaces in the same step. Because the cleaning and corrosion inhibiting is accomplished in a single step, there is less likelihood of accidental contamination by handling a completely separate solution. Furthermore, valuable processing time is saved by not having to add an additional inhibiting step. Some preferred embodiments of the cleaning solution include a surface-active agent, also referred to as a surface-wetting agent. The surface-active agent helps prevent spotting (watermarks) on the surface that can be a source of contamination or hide defects in the semiconductor work-piece.

Problems solved by technology

This length of wire would severely compromise the chip's speed performance without design changes.

Corrosion of the metal surfaces results in metal recess and thinning of the metal lines.

However, these references suffer from one or more of the disadvantages discussed below.

Any oxidation or corrosion on the surface or recess of the metal causes thinning of the lines (dissolution) and results in poor performance or failure of the semiconductor device.

Many cleaning solutions available in the art do not provide a film forming agent, and thus suffer from a high static etch rate and / or high RMS value.

Some existing acidic cleaning chemistries do not passivate the metal, resulting in corrosion during and after the cleaning step by oxidation of the metal surface.

Some rinsing agents can leave deposits on the surface of the work-piece, thus contaminating the wafer.

Adding a second step is also a drawback due to the fact that it lengthens the manufacturing process, complicates the process by having to handle more chemicals and more steps, and provides one more possible source of contamination or other quality control problems.

These complexing chemicals are referred to as “chelating agents.” Cleaning solutions using chemistry that cannot complex the residual metals typically perform poorly at the desired cleaning task.

Another common problem with cleaning semiconductor surfaces is the deposition of contaminants on the surface of the semiconductor device.

Any cleaning solutions that deposit even a few molecules of undesirable composition, such as carbon, will adversely affect the performance of the semiconductor device.

Cleaning solutions that require a rinsing step can also result in depositing contaminants on the surface.

As indicated above, the available cleaning solutions do not adequately meet all of the requirements of post-CMP cleaning.

In some cases, the biodegradability is also unsatisfactory.

Thus, EDTA proves to have inadequate biodegradability in conventional tests, as does PDTA or HPDTA and corresponding aminomethylenephosphonates which, moreover, are often undesirable because of their phosphorus content.

This presents a problem for formulators where a chelating function is sought but only selectively to metal oxide and not the metal itself, e.g. in an application involving metal, such as copper.

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