Tungsten CMP Slurry with Polyethoxylated Tallow Amine for Corrosion Inhibition
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Solution Overview
Problem
Chemical mechanical polishing (CMP) of tungsten in integrated circuit fabrication faces challenges such as corrosion and dishing, leading to non-uniform surfaces and electrical performance issues, which existing CMP slurries fail to adequately address.
Innovation Solution
A CMP composition comprising water, an oxidizing agent, polyethoxylated tallow amine, colloidal silica abrasive, dicarboxylic acid, and iron ions, optionally with a pH adjusting agent and biocide, is used to inhibit corrosion and dishing during the polishing process, employing a specific formulation and polishing pad configuration to achieve effective tungsten removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aggressive CMP settings are used to polish tungsten, then polishing efficiency is improved, but tungsten corrosion increases
Solution Approach 1:
The invention changes the chemical parameters of the CMP slurry by introducing a specific polyethoxylated tallow amine compound with controlled ethoxylation degree (m+n=2-24). This compound modifies the chemical interaction between slurry and tungsten, enabling effective polishing while reducing corrosion. The oxidizing agent concentration and pH are also optimized to achieve the right balance between polishing rate and corrosion inhibition.
Solution Approach 2:
The invention uses a composite slurry formulation combining multiple components: polyethoxylated tallow amine, oxidizing agents, colloidal silica abrasive, and dicarboxylic acid. This composite approach creates synergistic effects where each component contributes to both polishing efficiency and corrosion protection, resolving the contradiction between aggressive polishing and corrosion prevention.
2Productivity
If aggressive CMP settings are used to remove tungsten, then removal rate is improved, but dishing increases
Solution Approach 1:
The invention optimizes physical parameters including slurry flow rate, pad rotation speed, and downforce to achieve high removal rates while maintaining surface uniformity. The chemical composition parameters are also tuned to enable softer, more uniform material removal rather than aggressive mechanical removal that causes dishing.
Solution Approach 2:
The invention reduces reliance on purely mechanical removal by enhancing the chemical component of CMP through the polyethoxylated tallow amine and oxidizing agents. This chemical assistance enables effective tungsten removal with reduced mechanical aggression, thereby preventing dishing while maintaining high productivity.
3Object-affected harmful factors
If corrosion-resistant slurry is used to protect tungsten, then corrosion is inhibited, but polishing aggressiveness decreases
Solution Approach 1:
The invention carefully adjusts the concentration and type of corrosion-inhibiting compounds to maintain protection while preserving polishing aggressiveness. The oxidizing agent strength and pH are optimized to enable sufficient chemical reaction for effective polishing without excessive corrosion. The polyethoxylated tallow amine concentration is tuned to provide corrosion resistance without overly softening the polishing action.
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 inhibits tungsten corrosion and reduces dishing, ensuring planar surfaces and improved electrical performance by maintaining a controlled pH and using a polyurethane polishing pad with polymeric hollow core microparticles, achieving a tungsten removal rate of ≥1000 Å/min with optimized process settings.
Implementation Method 1
an oxidizing agent
Implementation Method 2
a colloidal silica abrasive
Data Source
AI summary
A composition and method for chemical mechanical polishing a substrate containing tungsten to at least inhibit corrosion of the tungsten. The composition includes, as initial components: water; an oxidizing agent; a select polyethoxylated tallow amine; a dicarboxylic acid, a source of iron ions; a colloidal silica abrasive; and, optionally, a pH adjusting agent; and, optionally, a biocide. The chemical mechanical polishing method includes providing a chemical mechanical polishing pad, having a polishing surface; creating dynamic contact at an interface between the polishing pad and the substrate; and dispensing the polishing composition onto the polishing surface at or near the interface between the polishing pad and the substrate; wherein some of the tungsten is polished away from the substrate and corrosion of the tungsten is inhibited.