Polycationic CMP Slurry Additives for Tungsten Dishing Control
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Solution Overview
Problem
Existing chemical mechanical planarization (CMP) slurries face challenges in minimizing dishing and erosion of tungsten lines and arrays of metal lines, which are critical parameters affecting the planarity of polished wafers, especially in highly selective tungsten slurries.
Innovation Solution
The development of polycationic polymers or copolymers formed by at least one first cationic monomer and at least one second cationic monomer with different cationic groups, integrated into CMP slurries to reduce dishing and erosion while maintaining desirable polishing rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If highly selective tungsten slurry is used to increase metal removal rate, then productivity is improved, but dishing and erosion of metal lines worsen
Solution Approach 1:
The invention changes the chemical composition parameters of the slurry by incorporating specific polymers (polyethyleneimine, chitosan, or their derivatives) at controlled concentrations (0.01-5 wt%). These polymer additives modify the chemical reactivity and adsorption characteristics of the slurry, enabling selective suppression of dishing and erosion while preserving high metal removal rates through optimized chemical-mechanical interaction
Solution Approach 2:
The invention creates a composite slurry system combining traditional abrasive particles (colloidal silica, ceria) with polymer additives (polyethyleneimine, chitosan). This composite formulation synergistically integrates mechanical abrasion with chemical etching enhanced by polymer-mediated tungsten oxide dissolution, achieving both high productivity and superior planarity control
2Ease of manufacture
If conventional CMP slurry is used to maintain simple composition, then ease of manufacture is improved, but ability to control dishing and erosion worsens
Solution Approach 1:
The invention modifies the slurry composition by introducing polymer additives with specific functional groups (amine, hydroxyl) at optimized concentrations. These parameter changes enable the slurry to selectively adsorb onto tungsten surfaces and modulate chemical etching rates, providing precise control over dishing and erosion while maintaining relatively simple manufacturing procedures
Solution Approach 2:
The polymer additives (polyethyleneimine, chitosan) act as intermediaries between the abrasive particles and the tungsten surface. They facilitate controlled chemical etching by forming complexes with tungsten oxide, mediating the removal process to achieve uniform planarity while keeping the overall slurry formulation straightforward and manufacturable
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 polycationic polymers effectively suppress dishing and erosion in tungsten CMP processes, enhancing the selectivity and planarity of polished wafers by optimizing the removal rates of metal and dielectric layers.
Implementation Method 1
polycationic polymers or copolymers formed by at least one first cationic monomer and at least one second cationic monomer with different cationic groups
Implementation Method 2
the polycationic polymers effectively suppress dishing and erosion in tungsten CMP processes
Implementation Method 3
Removal of tungsten in the CMP is believed to be due to synergy between mechanical abrasion and tungsten oxidation followed by dissolution
Implementation Method 4
tungsten oxidation followed by dissolution
Data Source
AI summary
Synthesis of polycationic polymer or copolymer is disclosed. The polycationic polymer or copolymer are formed by at least one first cationic monomer and at least one second cationic monomer wherein the first cationic monomer and the second cationic monomer have different cationic groups; such as imidazolium group and non-imidazolium group. Chemical Mechanical Planarization (CMP) slurries comprise abrasives; activator; oxidizing agent; additive comprising polycationic polymer or copolymer; and water are also disclosed. The use of the synthesized polycationic polymer or copolymer in the CMP slurries reduces dishing and erosion in highly selective tungsten slurries.