CMP Composition for Cobalt Polishing with Neutral pH and Corrosion Inhibitors

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Solution Overview

Problem

Current chemical mechanical polishing (CMP) compositions for semiconductor substrates containing cobalt and cobalt alloys face challenges such as high corrosion, low material removal rates, and incompatibility with low k dielectric materials, leading to issues like dishing and delamination, particularly due to acidic pH and the need for separate corrosion inhibitors.

Innovation Solution

A CMP composition comprising inorganic particles, a substituted aromatic compound with carboxylic acid functions as a corrosion inhibitor, amino acids, hydrogen peroxide as an oxidizer, and an aqueous medium, optimized to operate within a neutral to alkaline pH range (7-10), which improves corrosion inhibition and adjustability of material removal rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If acidic pH CMP composition is used, then material removal rate of copper and cobalt is improved, but corrosion of cobalt increases and dishing occurs

Engineering Contradiction:

Improvematerial removal rateVSAvoidcorrosion of cobalt

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the pH parameter from acidic to neutral range (pH 7-9), fundamentally altering the chemical environment to reduce cobalt corrosion while maintaining effective material removal through the synergistic action of substituted aromatic carboxylic acids and amino acids

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces substituted aromatic carboxylic acids and amino acids as intermediary substances that mediate between the polishing particles and cobalt surface, providing corrosion inhibition while enabling controlled material removal through chemical complexation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If oxidizer is added to CMP composition, then polishing performance is improved, but dissolution of cobalt adhesion layer increases causing delamination

Engineering Contradiction:

Improvepolishing performanceVSAvoidadhesion layer stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The substituted aromatic carboxylic acids and amino acids act as intermediary protective agents that form complexation layers on the cobalt surface, preventing direct contact between the oxidizer and cobalt adhesion layer, thus avoiding dissolution and delamination while maintaining polishing effectiveness

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The corrosion inhibitors (substituted aromatic carboxylic acids and amino acids) are pre-added to the CMP composition to establish protective complexation on cobalt surfaces before oxidative polishing begins, preventing harmful dissolution in advance

Inventive Principle:

Principle #9Preliminary anti-action

3Object-affected harmful factors

If separate corrosion inhibitor is used, then corrosion protection is improved, but device complexity and process steps increase

Engineering Contradiction:

Improvecorrosion protectionVSAvoidprocess complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the corrosion inhibition function with the polishing slurry composition itself by incorporating substituted aromatic carboxylic acids and amino acids directly into the CMP formulation, eliminating the need for separate corrosion inhibitor applications or process steps

Inventive Principle:

Principle #5Merging (Combining)

4Productivity

If material removal rate is increased, then productivity is improved, but dishing of copper lines occurs

Engineering Contradiction:

Improvematerial removal rateVSAvoidsurface flatness

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent adjusts multiple parameters including pH (to neutral 7-9), chemical composition (substituted aromatic carboxylic acids and amino acids), and oxidizer concentration to achieve an optimized balance that enables high material removal rates while maintaining surface flatness and preventing dishing through controlled chemical-mechanical interaction

Inventive Principle:

Principle #35Parameter changes

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 achieves high cobalt material removal rates with reduced corrosion and improved surface quality, compatibility with low k dielectric materials, and stability, while minimizing dishing and delamination risks.

Implementation Method 1

a substituted aromatic compound with at least one carboxylic acid function as a corrosion inhibitor

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

at least one amino acid

Methodology Applied

Scientific EffectComplexation: Chemical Bonding

Implementation Method 3

at least one oxidizer

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 4

inorganic particles

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS10385236B2Use of a chemical mechanical polishing (CMP) composition for polishing of cobalt and / or cobalt alloy comprising substrates

Publication Date: 2019.08.20 BASF SE

AI summary

A chemical mechanical polishing (CMP) composition (Q) for chemical mechanical polishing of a substrate (S) containing (i) cobalt and/or (ii) a cobalt alloy, wherein the CMP composition (Q) contains: (A) Inorganic particles, (B) a substituted aromatic compound with at least one carboxylic acid function as corrosion inhibitor, (C) at least one amino acid, (D) at least one oxidizer, (E) an aqueous medium, wherein the CMP composition (Q) has a pH of from 7 to 10.