CMP Slurry Aluminum Additive for Silicon Nitride Selectivity
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Solution Overview
Problem
Current CMP technologies face challenges in achieving low removal rates for silicon-containing films like silicon nitride and silicon carbide while maintaining high removal rates for other layers, especially when using silica particles as abrasives and requiring a higher pH, which can lead to hydrolysis and increased removal rates of these films.
Innovation Solution
The use of a water-soluble aluminum compound, such as sodium aluminate or potassium aluminate, in CMP slurries to suppress the removal rates of silicon-containing films by forming an insoluble complex that inhibits further hydrolysis, combined with colloidal silica particles and an oxidizing agent, at a pH above 7 to ensure effective polishing without over-removing the stop layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ceria particles are used as abrasive, then selectivity for silicon oxide to silicon nitride is improved, but compatibility with silica particles and oxidizers is lost
Solution Approach 1:
The invention achieves multi-functionality by combining silica particles (which provide high removal rates and compatibility with oxidizers) with aluminum compounds (which provide the selectivity control previously only available with ceria), thereby creating a slurry system that delivers both high productivity and precise selectivity control
Solution Approach 2:
The slurry composition is designed as a composite system combining silica abrasive particles with aluminum compound additives, where each component contributes different functions: silica provides mechanical removal capability and oxidizer compatibility, while aluminum compounds provide selective inhibition of silicon-containing film removal
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
This approach effectively reduces the removal rates of silicon-containing films like SiN and SiC while maintaining high removal rates for other films, achieving desirable selectivity and minimizing defects and dishing, with the ability to tune removal rates based on aluminate concentration.
Implementation Method 1
The use of a water-soluble aluminum compound, such as sodium aluminate or potassium aluminate, in CMP slurries to suppress the removal rates of silicon-containing films by forming an insoluble complex that inhibits further hydrolysis
Implementation Method 2
combined with colloidal silica particles and an oxidizing agent, at a pH above 7 to ensure effective polishing without over-removing the stop layer
Implementation Method 3
combined with colloidal silica particles and an oxidizing agent, at a pH above 7 to ensure effective polishing
Data Source
AI summary
Chemical mechanical polishing (CMP) compositions, methods and systems are for polishing patterned semiconductor wafers. The CMP compositions comprising an abrasive and a water soluble aluminum compound additive with a pH>7 suppress CMP stop layer (a silicon containing layer, such as silicon nitride, silicon oxide, or silicon carbide) removal rate. CMP compositions optionally contain surfactant to help wet surface; a corrosion inhibitor to provide corrosion inhibition on metal lines, vias, or trenches; and a pH adjusting agent that is used to adjust pH of the CMP polishing composition.