CMP Slurry for Cobalt and TiN/TaN Polishing
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) compositions face challenges in achieving high material removal rates for cobalt and TiN/TaN while maintaining low etching rates and compatibility with low k dielectric materials, leading to issues like dishing and delamination in semiconductor manufacturing.
Innovation Solution
A CMP composition comprising colloidal silica particles, specific organic compounds with amino and acid groups, hydrogen peroxide, and corrosion inhibitors in an aqueous medium with a pH between 6 and 9, which enhances the material removal rates of cobalt and TiN/TaN while minimizing etching of silicon oxide and improving surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acidic CMP compositions are used to increase material removal rate of cobalt and TiN/TaN, then polishing efficiency is improved, but etching rate of silicon oxide increases causing dishing and delamination
Solution Approach 1:
The patent changes the pH parameter of the CMP composition from acidic to neutral or alkaline range (pH 7-10.5), which fundamentally alters the chemical reactivity profile. This parameter change enables high material removal rates for cobalt and TiN/TaN while suppressing etching of silicon oxide, resolving the contradiction between polishing efficiency and harmful etching effects
Solution Approach 2:
The patent employs a composite slurry system combining colloidal silica particles (mechanical polishing agent) with specific organic compounds containing amino and acid groups (chemical reaction agents). This composite approach enables selective chemical-mechanical removal of metals and nitrides while being gentle on dielectric materials, simultaneously achieving high productivity and low harmful etching
2Productivity
If high material removal rate is achieved for cobalt and TiN/TaN, then polishing efficiency is improved, but surface quality deteriorates due to dishing
Solution Approach 1:
By adjusting the pH to neutral or alkaline range and controlling the oxidizer concentration (0.1-5% hydrogen peroxide), the patent achieves an optimal balance between material removal rate and surface quality. This parameter optimization prevents excessive etching that causes dishing while maintaining high polishing efficiency for cobalt and TiN/TaN layers
Solution Approach 2:
The organic compounds containing both amino and acid groups act as intermediaries that facilitate controlled chemical reaction with cobalt and TiN/TaN surfaces. These intermediaries enable uniform material removal without aggressive etching, maintaining surface quality while achieving high productivity
3Productivity
If oxidizer concentration is increased to improve material removal rate, then polishing efficiency is improved, but delamination occurs due to excessive etching
Solution Approach 1:
The patent optimizes the oxidizer concentration parameter to a specific range (0.1-5% hydrogen peroxide) and combines it with neutral to alkaline pH conditions. This parameter combination achieves effective material removal while preventing excessive etching that would compromise adhesion and cause delamination, thus maintaining reliability
4Object-generated harmful factors
If neutral to alkaline pH is used to reduce etching of silicon oxide, then harmful etching is reduced, but material removal rate of cobalt and TiN/TaN decreases
Solution Approach 1:
The patent creates a composite slurry system that combines colloidal silica particles for mechanical polishing with organic compounds containing amino and acid groups for chemical enhancement. This composite formulation enables the slurry to maintain neutral or alkaline pH (reducing harmful etching) while still achieving high material removal rates through the synergistic action of mechanical abrasion and targeted chemical reactions
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 proposed CMP composition achieves high material removal rates for cobalt and TiN/TaN with controlled selectivity, reducing dishing and delamination, and is storage-stable with a neutral to alkaline pH, ensuring good surface finish and compatibility with low k dielectric materials.
Implementation Method 1
Chemical action is provided by a chemical composition, also referred to as CMP composition or CMP slurry
Implementation Method 2
Mechanical action is usually carried out by a polishing pad which is typically pressed onto the to-be-polished surface
Implementation Method 3
copper and cobalt easily suffered from dissolution in acidic solution containing oxidant for example hydrogen peroxide
Data Source
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 and (iii) Ti N and/or TaN, wherein the CMP composition (Q) comprises (E) Inorganic particles (F) at least one organic compound comprising an amino-group and an acid group (Y), wherein said compound comprises n amino groups and at least n+1 acidic protons, wherein n is a integer≥1. (G) at least one oxidizer in an amount of from 0.2 to 2.5 wt.-% based on the total weight of the respective CMP composition, (H) an aqueous medium wherein the CMP composition (Q) has a pH of more than 6 and less than 9.