Copper polishing cleaning solution

Abstract

A cleaning solution for removing copper complex residues from the surface of polishing pads and wafer substrates includes an amine pH-adjusting agent, which can be a unidentate or bidentate amine compound or a quartnary ammonium hydroxide compound or an amine including an alcohol group. The cleaning solution also includes an amino acid complexing agent and an inhibitor. In a preferred embodiment, the cleaning solution has a basic pH.

Description

[0001] This application is a continuation in part of application Ser. No. 10 / 006,491, filed Dec. 7, 2001.[0002] The invention relates generally to cleaning a fluid compositions and to methods of their use and, more particularly, to a cleaning solution for removing copper polishing residues from polishing pads and wafer substrates.[0003] Silicon wafers are widely used as substrates on which multilevel integrated circuits are fabricated. Integrated circuits on a semiconductor wafer are typically manufactured with insulating layers, semiconductive layers, such as polysilicon, and conductive metals substrate layers, such as tungsten, aluminum, copper and platinum. The dielectric materials can be a dielectric, such as, silica including thermally grown SiO.sub.2 and chemical vapor deposited SiO.sub.2 using tetraethylorthosilane gas (TEOS). Further, advanced integrated circuits often employ low K dielectric materials.[0004] In circuit fabrication, a series of deposition and etch steps is r...

AI Technical Summary

Benefits of technology

[0010] The present invention addresses the cleaning problem associated with copper polishing by providing a cleaning solution that breaks down Cu-BTA complex bonds and prevents re-deposition of copper. The cleaning solution also minimizes excess copper etching and corrosion during polishing and post CMP cleaning. In a preferred embodiment, the cleaning solution includes a complexing agent and an azole inhibitor, where the complexing agent dissolves copper residue from a metal surface and forms copper ions in solution. The complexing agent maintains the copper ions in solution and substantially prevents the copper ions from redepositing on the metal surface.

Problems solved by technology

A non-planar surface is created during these manufacturing processes, which can cause focusing problems for photolithography equipment.

Poor focusing during lithographic alignment and registration results in low yield and decreased device performance.

Due to the difficulty and high cost associated with dry etching copper alloys, trenches or damascene structures are dry etched into dielectric films and then filled with barrier layer followed by copper seed and electroplating of copper.

Since the slurry flow pattern is especially disturbed in areas where the wafer contacts the polish pad, the residue adversely affects polishing uniformity.

Due to insolubility of slurry by-products, however, DI-water is largely ineffective at cleaning the pads and even a high pressure DI water spray is ineffective in removing the sticky BTA-Cu-polymer complex.

Although, conventional diamond grid disks are widely used to remove debris from polishing pads, the disks only condition the surface of the pad and cannot remove the residue within the polish pad grooves.

Also, brush conditioners simply disturb the residue within the grooves and are largely unable to condition the pad surface and remove the residue.

Using conventional cleaners in combination with a condition brush can be effective at reducing the residue on the polishing pad, but this process requires long condition times, which reduces the overall throughput of the polisher.

Also, due to the slow dissolution kinetics of Cu-BTA complex residue in conventional cleaners, the condition brushes become contaminated during the conditioning process.

Further, even in-situ conditioning during polishing with a diamond conditioner disk does not efficiently remove the insoluble residues within the pad groove.

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