Cobalt CMP Composition Using Poly(amino Acid) for Corrosion Control

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Solution Overview

Problem

Current chemical mechanical polishing (CMP) compositions for semiconductor substrates face challenges in achieving selective and corrosion-resistant removal of cobalt and cobalt alloys while maintaining high material removal rates and surface quality, particularly in the presence of low k dielectric materials and other metals like copper.

Innovation Solution

A CMP composition comprising colloidal silica particles, a poly(amino acid) or its salt, an amino acid, hydrogen peroxide, and an aqueous medium, with a pH range of 7 to 10, which acts as a corrosion inhibitor and adjusts the etching behavior for improved cobalt and cobalt alloy polishing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If acidic CMP compositions are used to reduce damage to low-k dielectrics, then polishing performance is improved, but cobalt and copper easily suffer from dissolution leading to high etching rates and dishing

Engineering Contradiction:

Improveprotection of low-k dielectricsVSAvoiddissolution of cobalt and copper

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the pH parameter from acidic to neutral or alkaline range (pH 7-10), which fundamentally alters the chemical environment to prevent dissolution of cobalt and copper while maintaining protection of low-k dielectrics through controlled chemical mechanisms appropriate for neutral/alkaline conditions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces specific chemical intermediaries including poly(amino acid) corrosion inhibitors, amino acids, and oxidizers that mediate the interaction between the CMP composition and cobalt/copper surfaces, enabling selective removal while preventing unwanted dissolution and corrosion

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If high material removal rates are achieved through acidic solutions with oxidants, then polishing efficiency is improved, but corrosion of cobalt adhesion layer occurs leading to delamination

Engineering Contradiction:

Improvematerial removal rateVSAvoidadhesion layer integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent converts the potentially harmful effect of oxidants into a beneficial process by controlling oxidation to occur only on the cobalt surface in a controlled manner, enabling material removal while the oxidized cobalt forms a protective layer that prevents further corrosion and maintains adhesion integrity

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the chemical parameters by using neutral/alkaline pH conditions with specific oxidizers (potassium permanganate, sodium persulfate, hydrogen peroxide) that provide controlled oxidation capability, enabling material removal without the uncontrolled corrosion that occurs in acidic conditions

Inventive Principle:

Principle #35Parameter changes

3Strength

If traditional Ta/TaN barrier layer is used, then adhesion is provided, but resistivity is relatively high and copper cannot be directly electroplated

Engineering Contradiction:

ImproveadhesionVSAvoidelectroplating compatibility

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the material parameter from Ta/TaN to cobalt, which fundamentally alters the electrical and surface properties to achieve lower resistivity and direct electroplating compatibility with copper while maintaining adhesion functionality

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 CMP composition provides enhanced corrosion inhibition and adjustable material removal rates for cobalt and cobalt alloys, ensuring high surface quality and compatibility with low k dielectric materials, while reducing dishing and storage instability.

Implementation Method 1

a poly(amino acid) as a corrosion inhibitor

Methodology Applied

Scientific EffectCorrosion inhibition:

Implementation Method 2

at least one oxidizer

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 3

inorganic particles

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentEP3433327B1Use of a chemical mechanical polishing (CMP) composition for polishing of cobalt and / or cobalt alloy comprising substrates

Publication Date: 2020.05.20 BASF SE

Figure 1~3
Figure 4

AI summary

Use of a chemical mechanical polishing (CMP) composition (Q) for chemical mechanical polishing of a substrate (S) comprising (i) cobalt and/or (ii) a cobalt alloy, wherein the CMP composition (Q) comprises (A) Inorganic particles (B) a poly(amino acid) and or a salt thereof (C) at least one amino acid, (D) at least one oxidizer (E) an aqueous medium and wherein the CMP composition (Q) has a pH of from 7 to 10.