CMP Slurry with Lanthanide Cations for Selective Oxide Polishing
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Solution Overview
Problem
Conventional polishing compositions for shallow trench isolation (STI) substrates often result in overpolishing and topographical defects like dishing, which can lead to short-circuits and degrade device quality and performance.
Innovation Solution
A chemical-mechanical polishing composition comprising ceria abrasive, cations of lanthanide metals, and nonionic polymers, which provides selective removal rates for silicon oxide, silicon nitride, and polysilicon with low particle defectivity and dishing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing compositions are used on STI substrates, then polishing action occurs, but overpolishing and topographical defects like dishing occur
Solution Approach 1:
The polishing composition modifies chemical parameters by incorporating specific additives that alter the polishing mechanism from purely mechanical to chemically-enhanced mechanical removal. This enables selective removal of oxide and nitride at controlled rates while protecting polysilicon, achieving high removal rates without overpolishing defects
Solution Approach 2:
The polishing composition acts as an intermediary between the polishing pad and substrate, providing selective chemical interaction with oxide and nitride layers. The composition mediates the polishing process to achieve uniform removal rates across different materials, preventing dishing and topographical defects
2Manufacturing precision
If polishing is performed to achieve planarity, then surface flatness improves, but defects and surface imperfections increase
Solution Approach 1:
The polishing composition converts potentially harmful mechanical abrasion into beneficial chemically-assisted removal. By incorporating chemical additives, it enables smooth planarization without generating defects or surface imperfections that would result from purely mechanical polishing
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 high removal rates for silicon oxide and silicon nitride while minimizing removal of polysilicon, reducing defects and surface imperfections, thereby enhancing the quality and reliability of STI substrates.
Implementation Method 1
Polishing compositions (also known as polishing slurries) typically contain an abrasive material in a liquid carrier and are applied to a surface by contacting the surface with a polishing pad saturated with the polishing composition
Implementation Method 2
A chemical-mechanical polishing composition comprising ceria abrasive, cations of lanthanide metals, and nonionic polymers, which provides selective removal rates for silicon oxide, silicon nitride, and polysilicon
Data Source
AI summary
The invention relates to a chemical-mechanical polishing composition comprising a ceria abrasive, cations of one or more lanthanide metals, one or more nonionic polymers, water, and optionally one or more additives. The invention further relates to a method of chemically-mechanically polishing a substrate with the inventive chemical-mechanical polishing composition. Typically, the substrate comprises one or more of silicon oxide, silicon nitride, and polysilicon.