CMP Slurry Corrosion Inhibitors for Copper Protection
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) processes for semiconductor manufacturing face challenges in protecting copper vias and trenches from further corrosion during and after polishing, as existing corrosion inhibitors like BTA form multilayer films, reduce removal rates, and are less effective in basic solutions.
Innovation Solution
A CMP polishing composition comprising cyanurate, isocyanurate, or oxalic acid, along with an abrasive and an oxidizing agent, is used to form a thin protective layer on copper surfaces, reducing corrosion without significantly impacting removal rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If BTA is used as a corrosion inhibitor in CMP slurry, then copper vias or trenches are protected from corrosion, but removal rates are undesirably reduced due to formation of insoluble polymeric films
Solution Approach 1:
The invention changes the chemical composition parameters by replacing BTA with alternative corrosion inhibitors such as substituted benzotriazoles, benzimidazoles, or carboxylic acids. These alternative compounds have different molecular structures and solubility characteristics that prevent the formation of insoluble polymeric films while maintaining corrosion protection, thus resolving the contradiction between reliability and productivity
Solution Approach 2:
The invention uses corrosion inhibitors that form monolayer protective films rather than multilayer polymeric films. These monolayer films are thinner, more soluble, and do not accumulate to form insoluble deposits, allowing for continuous removal process without significant rate reduction while still providing adequate corrosion protection
2Reliability
If BTA concentration is increased to improve corrosion inhibition, then protection effectiveness increases, but removal rates are further reduced due to insoluble film formation
Solution Approach 1:
The invention changes the chemical nature of the corrosion inhibitor from BTA to alternative compounds with different solubility and film-forming characteristics. These alternatives maintain protection effectiveness at lower concentrations without forming insoluble polymeric films, thus improving both reliability and productivity simultaneously
3Reliability
If BTA is used in basic solutions, then corrosion protection is provided, but effectiveness is reduced compared to acidic conditions
Solution Approach 1:
The invention selects corrosion inhibitors with chemical structures that are specifically adapted to basic solution environments. Compounds such as certain substituted benzotriazoles, benzimidazoles, and carboxylic acids exhibit enhanced stability and film-forming capability in basic pH conditions, thereby improving adaptability while maintaining reliability
Solution Approach 2:
The invention uses corrosion inhibitors that act as effective intermediaries between the copper surface and the basic CMP slurry environment. These compounds form stable protective films that mediate the interaction between basic solution components and copper, preventing corrosion even in high pH conditions where BTA fails
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition effectively reduces copper surface corrosion, maintains desirable removal rates, and provides low residue and uniformity in CMP processing, outperforming traditional BTA-based inhibitors.
Implementation Method 1
A CMP polishing composition comprising cyanurate, isocyanurate, or oxalic acid, along with an abrasive and an oxidizing agent, is used to form a thin protective layer on copper surfaces, reducing corrosion without significantly impacting removal rates
Implementation Method 2
The chemical reactions involved in using a barrier CMP slurry include: oxidation reactions induced by the oxidant used in the barrier CMP slurry, for example, H2O2. The surfaces of copper vias or trenches, and barrier material, such as Ta, are oxidized into the relative metal oxide films
Implementation Method 3
Typically, abrasives are also used in most barrier CMP slurries; the abrasives with variable particle size provide mechanical friction forces between polishing pad and wafer surface under applied pressure
Data Source
AI summary
A CMP composition and associated method are provided that afford good corrosion protection and low defectivity levels both during and subsequent to CMP processing. This composition and method are useful in CMP (chemical mechanical planarization) processing in semiconductor manufacture involving removal of metal(s) and/or barrier layer material(s) and especially for CMP processing in low technology node applications.