CMP Slurry Composition for Selective Silicon Nitride Polishing
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Solution Overview
Problem
Current chemical mechanical polishing slurries lack selectivity in polishing rates for Silicon Nitride, Silicon oxide, and Polysilicon, leading to inefficient removal and surface control during semiconductor manufacturing, especially when Silicon Oxide and Polysilicon are used as stop layers.
Innovation Solution
A chemical mechanical polishing slurry formulation incorporating silicon dioxide particles, a nitrogen-containing heterocyclic compound with carboxyl groups, and an ethoxylated butoxylated alkyl alcohol, which enhances the polishing rate for Silicon Nitride while maintaining low rates for Silicon oxide and Polysilicon, achieving selective polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing slurry is used, then oxide polishing rate is maintained, but Silicon Nitride polishing rate is insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters of the polishing slurry by introducing a nitrogen-containing heterocyclic compound with specific functional groups (carboxyl, hydroxyl, or amino groups) and controlling its concentration within 0.01-5 wt%. This parameter change enables the slurry to achieve high Silicon Nitride polishing rate while maintaining low oxide and polysilicon polishing rates, thereby resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent creates a composite polishing slurry system by combining silicon dioxide abrasive particles with nitrogen-containing heterocyclic compounds and water. This composite formulation synergistically enhances the polishing performance, where the heterocyclic compound selectively promotes Silicon Nitride removal while the silicon dioxide particles provide mechanical abrasion, achieving both high productivity and precision.
2Productivity
If high Silicon Nitride polishing rate is achieved, then removal efficiency improves, but oxide and polysilicon removal increases
Solution Approach 1:
The nitrogen-containing heterocyclic compound exhibits local quality by selectively interacting with Silicon Nitride through specific chemical mechanisms (complexation or coordination with nitrogen atoms) while having minimal effect on oxide and polysilicon. This selective action achieves high Silicon Nitride removal efficiency without significant loss of stop layer materials.
3Manufacturing precision
If polishing slurry removes excess dielectric material, then surface flatness improves, but Silicon Nitride layer is over-polished
Solution Approach 1:
The patent replaces purely mechanical polishing with a chemically-enhanced process. The nitrogen-containing heterocyclic compound introduces chemical reactions that selectively remove Silicon Nitride through complexation or coordination mechanisms, reducing reliance on mechanical abrasion and enabling precise control over Silicon Nitride removal while preserving the layer's integrity.
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 slurry achieves a significantly higher polishing rate for Silicon Nitride compared to Silicon oxide and Polysilicon, allowing precise control of substrate surface removal and suitable for processes where Silicon Oxide and Polysilicon are used as stop layers, thereby improving manufacturing efficiency.
Implementation Method 1
a nitrogen-containing heterocyclic compound having one or more carboxy group(s)
Implementation Method 2
chemical mechanical polishing slurry
Implementation Method 3
silicon dioxide particles
Implementation Method 4
chemical mechanical polishing
Data Source
AI summary
A chemical mechanical polishing slurry, including silicon dioxide particles, a nitrogen-containing heterocyclic compound having one or more carboxy group(s), and an ethoxylated butoxylated alky alcohol, and use of the chemical mechanical polishing slurry in the polishing silicon oxide, polysilicon, and silicon nitride. Polishing rate for silicon nitride using the polishing slurry is much higher than that for silicon oxide and polysilicon. The polishing slurry can be applied to chemical mechanical polishing in which silicon oxide/polysilicon is used as the stop layer, and can be used to control the amount of oxide and polysilicon removed from the substrate surface during polishing.