Tungsten CMP Slurry with Guar Gum and Iron Ions
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Solution Overview
Problem
Chemical mechanical polishing of tungsten often results in dishing of tungsten and erosion of underlying dielectric materials, leading to non-uniform substrate surfaces and increased static corrosion rates, which negatively impact the quality and performance of integrated circuits.
Innovation Solution
A chemical mechanical polishing method using a composition comprising water, an oxidizing agent, guar gum, colloidal silica abrasive, and a source of iron (III) ions, applied with a polishing pad to inhibit tungsten dishing and reduce static corrosion, while maintaining a tungsten removal rate of ≥1,000 Å/min.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP slurries are used to polish tungsten, then tungsten removal is achieved, but dishing of tungsten occurs and underlying dielectric erosion increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific polymers (guar gum, xanthan gum, carbomer) and controlling pH levels to achieve optimal polishing performance that prevents dishing while maintaining removal rate
Solution Approach 2:
The invention uses composite polishing slurries that combine multiple polymers with specific molecular weights and concentrations, creating a synergistic effect that provides both polishing capability and surface uniformity control
2Productivity
If conventional CMP slurries are used to polish tungsten, then tungsten removal is achieved, but static corrosion rate increases
Solution Approach 1:
The patent converts the potentially harmful corrosive action into a beneficial controlled process by using specific polymer additives that moderate the chemical reaction, allowing tungsten removal while minimizing excessive corrosion and improving surface quality
3Manufacturing precision
If polishing is performed to remove tungsten, then surface planarization is achieved, but erosion of underlying dielectric material occurs
Solution Approach 1:
The patent applies selective polishing action through controlled slurry composition that targets tungsten specifically while being less aggressive toward underlying dielectric materials, achieving planarization without excessive erosion
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 inhibits tungsten dishing and erosion of underlying dielectrics, reducing static corrosion rates and improving the surface quality of semiconductor substrates, thereby enhancing the performance of integrated circuits.
Implementation Method 1
an oxidizing agent
Implementation Method 2
a colloidal silica abrasive
Data Source
AI summary
A process for chemical mechanical polishing a substrate containing tungsten is disclosed to reduce static corrosion rate and inhibit dishing of the tungsten and erosion of underlying dielectrics. The process includes providing a substrate; providing a polishing composition, containing, as initial components: water; an oxidizing agent; guar gum; a dicarboxylic acid, a source of iron ions; a colloidal silica abrasive; and, optionally a pH adjusting agent; 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 (W) is polished away from the substrate, static corrosion rate is reduced, dishing of the tungsten (W) is inhibited as well as erosion of dielectrics underlying the tungsten (W).