CMP Slurry Composition for SiN Selectivity and Low W Dissolution
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Solution Overview
Problem
Existing CMP slurries face challenges in efficiently polishing surfaces with a combination of metal and dielectric film materials, particularly in maintaining high selectivity for silicon nitride (SiN) removal over tetraethyl orthosilicate (TEOS) while minimizing tungsten (W) dissolution, which can lead to increased electrical conductivity and localized corrosion.
Innovation Solution
A novel CMP composition comprising anionic modified colloidal silica abrasive, a SiN polishing rate enhancer, and an anionic surfactant, with specific pH and electrical conductivity ranges, is used to enhance SiN removal and buffer against TEOS removal, thereby improving robustness and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP slurries are used to polish surfaces with metal and dielectric film materials, then polishing can be performed, but the selectivity for SiN removal over TEOS is insufficient and W dissolution increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating specific anionic surfactants and adjusting pH to approximately 9, which changes the chemical reactivity parameters to achieve higher SiN:TEOS selectivity (greater than 40:1) while suppressing W dissolution through controlled chemical environment
Solution Approach 2:
The invention uses a composite slurry system combining anionic modified colloidal silica abrasive particles with anionic surfactants and specific chemical additives, creating a multi-component composition that simultaneously provides mechanical abrasion and chemical selectivity for SiN removal while protecting W from dissolution
2Productivity
If higher abrasive concentration is used to increase polishing rate, then productivity improves, but selectivity and control over removal ratios deteriorate
Solution Approach 1:
The patent optimizes the abrasive concentration parameter within a specific range (0.5-2.0 wt%) and combines it with pH adjustment and surfactant addition to decouple the relationship between polishing rate and selectivity, enabling high productivity while maintaining precise control over SiN:TEOS removal ratios greater than 40:1
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 a high SiN:TEOS removal ratio of greater than 40:1, reduces W dissolution, and maintains stable electrical conductivity, enhancing the planarization process for integrated circuits.
Implementation Method 1
anionic modified colloidal silica abrasive
Implementation Method 2
anionic surfactant
Implementation Method 3
chemical mechanical polishing
Data Source
AI summary
The present technology generally relates to compositions and methods for polishing surfaces comprising a metal and a dielectric film material. Embodiments include methods for polishing a surface comprising W, TEOS/SiO2 and SiN, comprising applying a polishing slurry comprising an abrasive, a SiN polishing rate enhancer, and an anionic surfactant, and methods of buffering a metal oxide salt in a CMP slurry to obtain an increased robustness against TEOS removal comprising polishing a surface comprising a metal and TEOS by applying a polishing slurry comprising an anionic modified colloidal silica abrasive and an anionic surfactant.