Cubiform Ceria CMP Slurry for Selective Oxide Planarization
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Solution Overview
Problem
Existing ceria abrasive-based chemical mechanical polishing (CMP) compositions lack improved removal rates, planarization efficiency, and material selectivity, particularly in polishing silicon-containing substrates like silicon oxide, silicon nitride, and polysilicon.
Innovation Solution
A CMP composition comprising cubiform ceria abrasive particles (50-500 nm) mixed with lanthanum oxide and anionic or nonionic compounds, maintained at a pH of 9-11, enhances polishing efficiency and selectivity by using a mixture of cerium oxide and lanthanum oxide abrasive particles with controlled shape and size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP slurry is used for removing silicon oxide, then oxide removal is achieved, but copper metal is also damaged and removed along with the oxide
Solution Approach 1:
The invention changes the chemical composition parameters of the CMP slurry by incorporating specific organic acids (formic acid, acetic acid, propionic acid, or butyric acid) at controlled concentrations (0.1-10 wt%), along with hydrogen peroxide (1-30 wt%) and controlled water content (60-95%). These parameter changes create a chemically selective environment that preferentially attacks silicon oxide while being gentler on copper metal, thereby achieving high oxide removal selectivity without damaging the underlying copper interconnects.
Solution Approach 2:
The invention uses a composite slurry formulation combining multiple chemical components: organic acids, hydrogen peroxide, water, and optional additives. This composite approach creates synergistic effects where the organic acids provide selective chemical etching of oxide, hydrogen peroxide enhances oxidation and removal efficiency, and the controlled water content maintains appropriate slurry viscosity and reactivity. The composite formulation achieves superior selectivity compared to conventional single-component slurries.
2Manufacturing precision
If CMP process is used to remove silicon oxide, then planarization is achieved, but the process is time-consuming and reduces productivity
Solution Approach 1:
The invention optimizes kinetic parameters of the CMP process by adjusting slurry flow rate, applied pressure, and rotational speed to achieve faster material removal rates. The chemical composition parameters (organic acid concentration, hydrogen peroxide content, water content) are specifically tuned to enhance reaction kinetics between the slurry and silicon oxide, enabling rapid oxide removal while maintaining surface planarity. This allows the process to achieve both high precision and improved productivity.
Solution Approach 2:
The invention incorporates preliminary chemical oxidation of the silicon oxide layer using hydrogen peroxide and organic acids before mechanical removal. This preliminary chemical action softens and pre-treats the oxide layer, making it more susceptible to subsequent mechanical removal by the CMP pad. This two-stage approach (chemical pre-treatment followed by mechanical removal) significantly accelerates the overall process while maintaining surface quality, thereby improving productivity without sacrificing planarization precision.
3Manufacturing precision
If conventional slurry composition is used, then oxide removal is achieved, but the slurry is not stable and requires frequent monitoring
Solution Approach 1:
The invention carefully controls critical composition parameters including organic acid concentration (0.1-10 wt%), hydrogen peroxide content (1-30 wt%), and water content (60-95%). These parameter ranges are optimized to ensure chemical stability and consistent performance. The controlled composition prevents premature decomposition, maintains predictable reactivity with silicon oxide, and ensures uniform material removal across different batches, thereby achieving both manufacturing precision and compositional stability.
Solution Approach 2:
The invention uses stable, commercially available organic acids (formic acid, acetic acid, propionic acid, or butyric acid) that provide consistent performance without requiring complex stabilization systems. These materials are selected for their inherent stability, availability, and cost-effectiveness, allowing the slurry to maintain composition stability during storage and use without frequent monitoring or expensive additives.
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 provides significantly improved silicon oxide removal rates, increased throughput, and enhanced selectivity to silicon nitride and polysilicon layers, offering improved process flexibility and efficiency in CMP processes.
Implementation Method 1
The composition comprises hydrofluoric acid, ammonium bifluoride, and hydrogen peroxide
Implementation Method 2
The composition comprises formic acid, acetic acid, propionic acid, or butyric acid
Data Source
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AI summary
A chemical mechanical polishing composition for polishing a substrate having a silicon oxygen material includes a liquid carrier, cubiform ceria abrasive particles dispersed in the liquid carrier, and at least one of an anionic compound and a nonionic compound.