Low-K Polishing Slurry with Hydrophilizing Booster and SiN Selectivity
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Solution Overview
Problem
Existing polishing slurry compositions struggle to achieve a high removal rate for low-k films due to their hydrophobic properties, and there is a need to enhance the interaction between abrasive particles and low-k films while maintaining selectivity for SiN films.
Innovation Solution
A slurry composition comprising ceria abrasive particles, a monomolecular organic acid dispersant, a SiN polishing inhibitor, and a low-k booster is used to hydrophilize the low-k film surface, enhancing the interaction between abrasive particles and the film, and controlling the removal rate of SiN films through N—H hydrogen bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing polishing slurry composition is used, then SiN film selectivity is maintained, but low-k film removal rate is low due to hydrophobic properties
Solution Approach 1:
A low-k booster is introduced as an intermediary substance that mediates between the hydrophobic low-k film surface and the polishing slurry. The booster contains hydrophilic groups that interact with the hydrophobic low-k film through hydrophobic interactions, while also being compatible with the aqueous slurry environment, thereby enabling effective polishing of the hydrophobic surface
Solution Approach 2:
The surface properties of the low-k film are chemically modified by the low-k booster, which changes the surface energy and wettability parameters. This parameter change transforms the hydrophobic surface into a more hydrophilic surface, enabling better interaction with the aqueous slurry and improving removal rate
2Productivity
If abrasive particles are increased to improve low-k removal rate, then productivity increases, but selectivity for SiN film decreases
Solution Approach 1:
The slurry composition is designed with different components having specialized local functions: ceria abrasive particles for mechanical removal, low-k booster for selective chemical interaction with low-k film, and SiN polishing inhibitor for protecting SiN regions. This local quality differentiation enables simultaneous achievement of high removal rate and high selectivity
Solution Approach 2:
The polishing slurry is formulated as a composite system containing multiple functional components (ceria particles, organic acid dispersant, low-k booster, SiN polishing inhibitor) that work synergistically. The composite nature allows the slurry to exhibit both aggressive polishing action on low-k film and selective protection of SiN film
3Productivity
If conventional dispersants are used, then slurry stability is maintained, but interaction between abrasive particles and low-k film is insufficient
Solution Approach 1:
The dispersant molecules are selected based on their ability to modify surface charge parameters and interfacial tension. The conventional dispersant is replaced with a specifically selected dispersant that optimizes the electrostatic and steric parameters for both slurry stability and enhanced interaction with the low-k film surface
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 low-k removal rate of 2,000 to 3,000 Å/min with a selectivity of 50:1 or more for low-k to SiN films, improving polishing efficiency and surface flatness.
Implementation Method 1
hydrophilizing a low-k film surface by a positively charged ceria slurry composition, to which a hydrophilic low-k booster is applied
Implementation Method 2
controlling a selectivity of the low-k film and a SiN film by reducing a removal rate of the SiN film by inducing N—H hydrogen bonding for nitrogen atoms on the SiN film
Implementation Method 3
CMP involves applying a slurry, such as a solution of an abrasive and an active compound, to a polishing pad, which then buffs away, planarizes, and polishes the surface
Data Source
AI summary
Provided is a slurry composition for low-k film polishing, the slurry composition including ceria abrasive particles, a dispersant, a SiN polishing inhibitor, and a low-k booster, in which the dispersant is monomolecular organic acid.