CMP Slurry for Low-k Dielectric Removal
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Solution Overview
Problem
The development of effective chemical-mechanical polishing compositions that can efficiently remove tantalum-based barrier materials and soft low-κ dielectric materials, which are softer and more brittle than conventional silicon oxide-based dielectrics, is complicated by their differing chemistry and unacceptably low removal rates with conventional CMP processes.
Innovation Solution
A chemical-mechanical polishing composition comprising silica in particulate form, a cationic silane compound, a carboxylic acid with seven or more carbon atoms, an oxidizing agent, and water, with a pH of 1 to 5, is used to polish substrates, enhancing removal rates for low-κ dielectric layers such as carbon doped silicon oxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP compositions are used to polish low-κ dielectric materials, then the polishing process is simple and familiar, but the removal rate is unacceptably low
Solution Approach 1:
The patent modifies the chemical composition parameters of the polishing slurry by incorporating specific organic acids (sulfonic, carboxylic, or phosphonic acids with specified chain lengths), oxidizing agents, and complexing agents in controlled concentrations to achieve enhanced removal rates for low-κ dielectric materials while maintaining processability
Solution Approach 2:
The polishing composition uses a composite formulation combining multiple chemical components including organic acids, oxidizing agents, complexing agents, and abrasive particles (colloidal silica or aluminum oxide) to create a synergistic system that effectively removes both soft low-κ dielectric materials and harder barrier layers
2Productivity
If polishing compositions are optimized for low-κ dielectric materials, then removal rate improves, but ability to remove barrier materials may be compromised
Solution Approach 1:
The polishing composition is designed as a universal formulation that can effectively remove multiple material types including soft low-κ dielectric materials, conventional silicon oxide-based dielectrics, and tantalum-based barrier materials, making it adaptable for use in different polishing steps without requiring composition changes
Solution Approach 2:
The patent carefully balances the concentrations and types of organic acids, oxidizing agents, and complexing agents to achieve a pH range (3-9) that enables effective removal of both soft dielectric materials and harder barrier layers, resolving the trade-off between removal rate and versatility
3Reliability
If conventional silicon dioxide-based dielectric materials are used, then dielectric strength is maintained, but dielectric constant is relatively high limiting circuit speed
Solution Approach 1:
The patent addresses this contradiction by enabling effective polishing of low-κ dielectric materials (such as porous silicon oxide, carbon-doped silicon oxide, or fluorinated silicon oxide) that have lower dielectric constants than conventional silicon dioxide, allowing circuit speed improvement while the polishing composition maintains reliability through controlled chemical formulation
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 composition achieves enhanced removal rates for low-κ dielectric layers, particularly carbon doped silicon oxide, compared to prior art methods, while maintaining stability and effectiveness in polishing copper and tantalum layers.
Implementation Method 1
an oxidizing agent that oxidizes a metal
Implementation Method 2
silica in particulate form
Data Source
AI summary
The invention provides a chemical-mechanical polishing composition for polishing a substrate. The polishing composition comprises silica, a compound selected from the group consisting of an amine substituted silane, a tetraalkylammonium salt, a tetraalkylphosphonium salt, and an imidazolium salt, a carboxylic acid having seven or more carbon atoms, an oxidizing agent that oxidizes a metal, and water. The invention further provides a method of chemically-mechanically polishing a substrate with the aforementioned polishing composition.