Tungsten CMP Slurry Composition for Dishing Reduction
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Solution Overview
Problem
Chemical mechanical polishing of tungsten often results in dishing, leading to non-uniform surfaces and corrosion, which negatively impacts the electrical performance of semiconductor integrated circuits, especially as feature sizes miniaturize.
Innovation Solution
A chemical mechanical polishing method using a composition comprising water, an oxidizing agent, arginine or its salts, colloidal silica abrasive, a dicarboxylic acid, and iron (III) ions, applied with a polishing pad to inhibit dishing and corrosion of tungsten features with dimensions of 100 μm or less, while maintaining a tungsten removal rate of ≥1000 Å/min.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional aggressive CMP settings are used to polish tungsten, then tungsten removal rate is improved, but dishing of tungsten features occurs
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition of the CMP slurry, specifically incorporating arginine or its salts along with a dicarboxylic acid and iron (III) ions. These chemical parameter changes enable effective tungsten removal while simultaneously inhibiting dishing, resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The invention uses a composite polishing composition that combines multiple chemical components (arginine, dicarboxylic acid, iron (III) ions, colloidal silica abrasive, and oxidizing agent) to achieve both high removal rate and minimal dishing. This composite approach allows the slurry to perform multiple functions simultaneously, addressing both productivity and precision requirements.
2Adaptability or versatility
If feature sizes are miniaturized to increase integration density, then device functionality is improved, but dishing becomes more severe
Solution Approach 1:
The patent addresses miniaturization challenges by changing the chemical parameters of the CMP process through the addition of arginine and dicarboxylic acid. These modifications make the polishing process suitable for smaller features by providing better control over material removal, thereby maintaining manufacturing precision as integration density increases.
3Shape
If aggressive polishing is used to achieve planarization, then surface flatness is improved, but corrosion of tungsten occurs
Solution Approach 1:
The patent converts the potentially harmful aggressive polishing action into a beneficial process by adding arginine and dicarboxylic acid to the slurry. These components modify the chemistry to enable effective material removal for planarization while simultaneously protecting against corrosion, thus converting a harmful side effect into a controlled and beneficial outcome.
Solution Approach 2:
The invention changes the chemical parameters of the polishing environment by incorporating arginine, dicarboxylic acid, and iron (III) ions. These parameter changes allow the process to achieve the desired surface flatness while controlling the corrosion rate, maintaining both shape quality and material integrity.
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 method effectively reduces dishing and corrosion of tungsten features, ensuring a substantially planar surface and good selectivity between tungsten and silicon dioxide, thereby enhancing the quality and performance of semiconductor surfaces.
Implementation Method 1
providing a polishing composition, containing, as initial components: water; an oxidizing agent
Implementation Method 2
a colloidal silica abrasive
Data Source
AI summary
A process for chemical mechanical polishing a substrate containing tungsten to at least reduce dishing of tungsten features of 100 μm or less. The process includes providing a substrate containing tungsten features of 100 μm or less; providing a polishing composition, containing, as initial components: water; an oxidizing agent; arginine or salts thereof; a dicarboxylic acid, a source of iron ions; a colloidal silica abrasive; and, optionally, a pH adjusting agent; and, optionally, a surfactant; and, optionally, a biocide; 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 yet at least reducing dishing of the tungsten features of 100 μm or less.