Tungsten CMP Slurry Composition for Recess Control
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) techniques for tungsten surfaces often result in recess formation, leading to surface non-planarity and complications in subsequent layer deposition, necessitating a method to reduce tungsten recessing while maintaining effective removal rates.
Innovation Solution
A CMP method using a polishing composition comprising an aqueous carrier with a polyamino compound, transition metal ion, chelating agent, particulate aluminum doped silica abrasive, oxidizing agent, and optionally an amino acid, applied at specific concentrations and ratios to minimize tungsten recessing during polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP techniques are used to remove tungsten film, then tungsten removal is achieved, but tungsten recess formation occurs leading to surface non-planarity
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific additives including polyamino compounds, metal ions, chelating agents, and amino acids. These parameter changes alter the chemical interaction mechanisms between the slurry and tungsten surface, reducing aggressive removal that causes recesses while maintaining adequate removal rates.
Solution Approach 2:
The invention uses a composite polishing slurry formulation combining multiple functional components: abrasive particles, polyamino compounds, metal ions, chelating agents, and amino acids. This composite composition works synergistically to provide both mechanical abrasion and controlled chemical reaction, achieving planar polishing with reduced recess formation.
2Reliability
If over-polishing is used to ensure complete removal of tungsten film, then removal completeness is improved, but tungsten recessing increases
Solution Approach 1:
The patent employs additives that provide feedback mechanisms during the polishing process. The polyamino compounds and metal ions interact with the tungsten surface and slurry composition dynamically, adjusting the chemical reactivity based on local conditions. This feedback control prevents over-polishing in areas where tungsten is already fully removed, maintaining surface planarity.
Solution Approach 2:
The chelating agents and amino acids act as intermediaries that modulate the interaction between metal ions and the tungsten surface. These intermediary substances control the rate and uniformity of chemical removal, ensuring complete tungsten elimination without creating excessive recesses that would compromise surface planarity.
3Device complexity
If conventional CMP composition is used, then polishing process is simple, but tungsten recess control is poor
Solution Approach 1:
The patent segments the polishing function into distinct chemical components, each performing a specific role: abrasives for mechanical removal, polyamino compounds for surface interaction control, metal ions for chemical reaction modulation, chelating agents for ion management, and amino acids for additional surface protection. This segmentation allows precise control over recess depth while maintaining a manageable composition structure.
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 described method effectively reduces tungsten recessing while maintaining useful removal rates, as demonstrated by reduced recess depths in tungsten pattern wafers polished with the composition, enhancing surface planarity and circuit integrity.
Implementation Method 1
a chelating agent, wherein the chelating agent comprises at least one compound selected from the group consisting of malonic acid, methylmalonic acid, ethylmalonic acid, phenylmalonic acid, and hydroxyethylidene-1,1-diphosphonic acid, and wherein the at least one metal ion and the chelating agent are present at a respective molar ratio of 0.5:1 to 2:1
Implementation Method 2
an aqueous carrier containing (a) a polyamino compound; (b) at least one metal ion selected from a transition metal ion and a group IIIA/IVA metal ion; (c) a chelating agent
Implementation Method 3
an oxidizing agent
Implementation Method 4
a particulate aluminum doped silica abrasive, wherein the aluminum doped silica abrasive is present in the composition, at point of use, at a concentration in the range of 0.05 to 3 percent by weight (wt%)
Data Source
Figure 1~2
AI summary
The present invention provides chemical-mechanical polishing (CMP) methods for polishing a tungsten containing substrate. The polishing compositions used with the methods of the invention comprise an aqueous carrier, an abrasive, a polyamino compound, a metal ion, a chelating agent, an oxidizing agent, and optionally, an amino acid. The methods of the invention effectively remove tungsten while reducing surface defects such as recesses typically associated with tungsten CMP.