CMP Slurry with Ionic Liquids for Copper Planarization
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Solution Overview
Problem
Current copper chemical mechanical planarization (CMP) technologies face challenges in achieving high metal removal rates with low within-wafer non-uniformity and minimizing dishing and erosion effects, which are critical for semiconductor manufacturing as feature sizes shrink.
Innovation Solution
A CMP polishing composition and method using an ionic liquid compound, such as an imidazolium salt, in combination with an abrasive and an oxidizing agent, which enhances copper removal rates while maintaining low within-wafer non-uniformity and reducing polishing residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP slurries with high selectivity for copper and barrier layer removal are used, then metal removal rate is improved, but dishing and erosion effects worsen
Solution Approach 1:
The patent changes the chemical composition parameters of the CMP slurry by incorporating specific organic acids (formic acid, acetic acid, propionic acid, or butyric acid) at controlled concentrations (0.1-10%). This chemical parameter modification enables simultaneous achievement of high copper removal rates and minimal dishing/erosion, resolving the contradiction between productivity and manufacturing precision
Solution Approach 2:
The invention creates a composite slurry system combining traditional abrasive particles with specific organic acid compounds and oxidizing agents. This composite formulation achieves synergistic effects where the organic acids provide selective copper dissolution while the abrasive particles perform mechanical removal, maintaining both high productivity and surface planarity
2Productivity
If higher abrasive loading is used to increase removal rate, then productivity is improved, but within-wafer non-uniformity worsens
Solution Approach 1:
The patent optimizes the concentration parameters of organic acids in the slurry formulation. By controlling acid concentration at 0.1-10%, the chemical dissolution rate is tuned to complement mechanical abrasion, enabling high removal rates while maintaining uniform material removal across the wafer surface, thus resolving the contradiction between productivity and manufacturing precision
3Productivity
If chemical reactivity is increased to improve removal rate, then productivity is improved, but polishing residues increase
Solution Approach 1:
The patent carefully controls the concentration parameters of organic acids and oxidizing agents in the slurry. By maintaining acid concentration at 0.1-10% and using specific oxidizing agents at controlled levels, the chemical reactivity is optimized to achieve high copper removal while minimizing residue formation through controlled dissolution and effective slurry flow dynamics
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 use of ionic liquid compounds in the CMP process significantly increases copper removal rates and reduces within-wafer non-uniformity, minimizing defects like dishing and erosion, thereby improving the planarity and quality of polished substrates.
Implementation Method 1
The polishing composition accomplishes the planarization (polishing) process by chemically and mechanically interacting with the substrate film being planarized
Implementation Method 2
Typically metal CMP slurries contain an abrasive material, such as silica or alumina, which is suspended in an oxidizing, aqueous medium
Implementation Method 3
Typically metal CMP slurries contain an abrasive material, such as silica or alumina
Implementation Method 4
the polishing composition accomplishes the planarization (polishing) process by chemically and mechanically interacting with the substrate film being planarized due to the effect of the rotational movement of the pad relative to the substrate
Data Source
AI summary
A composition and associated method for chemical mechanical planarization of a metal-containing substrate (e.g., a copper substrate) are described herein which afford high and tunable rates of metal removal as well as low within a wafer non-uniformity values and low residue levels remaining after polishing.