Tungsten Polishing Slurry Selectivity Control via Carboxyl Agent
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Solution Overview
Problem
Current polishing slurries for tungsten in semiconductor manufacturing lack high polishing selectivity between tungsten and insulation layers, leading to inefficient processes and reduced productivity due to excessive polishing or erosion.
Innovation Solution
A tungsten polishing slurry comprising zirconium oxide particles as abrasives, a selectivity control agent with a carboxyl group, an oxidizer, and a catalyst, which adjusts pH to an acidic range to suppress insulation layer polishing, enhancing selectivity and reducing dishing and erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing slurries are used for tungsten polishing, then the polishing process can be performed, but the polishing selectivity between tungsten and insulation layers is insufficient
Solution Approach 1:
The patent changes the chemical parameters of the polishing slurry by introducing a selectivity control agent containing a carboxyl group. This agent modifies the chemical environment during polishing, enabling selective removal of tungsten oxide while protecting the insulation layer. The carboxyl group specifically interacts with tungsten oxide, enhancing polishing selectivity and reducing harmful effects like erosion and dishing on the insulation layer.
Solution Approach 2:
The selectivity control agent acts as an intermediary substance between the abrasive and the substrate. It mediates the polishing reaction by preferentially binding to tungsten oxide, facilitating its removal while preventing the abrasive from directly attacking the insulation layer. This intermediary mechanism achieves high polishing selectivity without causing damage to underlying layers.
2Manufacturing precision
If various components are added to improve polishing selectivity, then selectivity may be enhanced, but the process complexity increases
Solution Approach 1:
The selectivity control agent with a carboxyl group serves multiple functions simultaneously: it acts as a pH buffer, a complexing agent for tungsten oxide, and a protective colloid for the insulation layer. This multi-functionality reduces the need for multiple separate additives, simplifying the overall slurry composition while maintaining high polishing selectivity.
Solution Approach 2:
The patent applies the principle of local quality by designing a slurry where the selectivity control agent specifically targets the tungsten oxide interface. The carboxyl group concentrates its action at the polishing contact point between the slurry and tungsten oxide, providing localized chemical enhancement without requiring uniform distribution of multiple complex components throughout the entire slurry system.
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 slurry achieves improved polishing selectivity between tungsten and insulation layers, reducing excessive polishing and byproduct generation, thereby enhancing manufacturing productivity and device reliability.
Implementation Method 1
the selectivity control agent includes an organic acid which generates a negatively charged functional group in an acidic region... suppresses polishing of a material other than the tungsten layer
Implementation Method 2
a process of forming a tungsten oxide (WO3) by an oxidizer... a slurry, which does not polish the insulation layer while well polishing the tungsten layer
Implementation Method 3
a process of removing the formed metal oxide with an abrasive repeatedly occur in a metal polishing process
Implementation Method 4
a catalyst configured to promote oxidation of the tungsten
Data Source
AI summary
Provided are a slurry for polishing tungsten and a method of polishing a substrate. The slurry according to an exemplary embodiment includes an abrasive configured to perform polishing and include particles having a positive zeta potential, a dispersant configure to disperse the abrasive, an oxidizer configured to oxidize a surface of the tungsten, a catalyst configured to promote oxidation of the tungsten, and a selectivity control agent configured to control a polishing selectivity and include an organic acid containing a carboxyl group. According to the slurry of the exemplary embodiment, a polishing selectivity between the tungsten and the insulation layer may be improved by suppressing a polishing rate of the insulation layer.