Dual-Charge CMP Slurry Composition for Balanced Oxide-Nitride Polishing
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Solution Overview
Problem
Existing CMP slurries face challenges in securing simultaneous polishing rates for various film types, including polysilicon, oxide, and nitride films, due to the use of single particle compositions, particularly with low solid content.
Innovation Solution
A slurry composition comprising two types of colloidal silica abrasive particles with different charges, a pH buffer, and a pH adjuster, which includes first colloidal silica abrasive particles with a neutral charge and second colloidal silica abrasive particles with a negative charge, to achieve balanced polishing rates for silicon oxide and silicon nitride films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If single particle slurry composition is used, then device complexity is reduced, but polishing rate for various film types cannot be secured
Solution Approach 1:
The patent applies composite materials by combining two types of colloidal silica abrasive particles with different charges (positive and negative) into a single slurry composition. This composite approach enables the slurry to effectively polish multiple film types (oxide, nitride, polysilicon, copper) simultaneously, resolving the contradiction between maintaining simple composition and achieving high polishing rates across various films.
Solution Approach 2:
The slurry composition achieves multi-functionality by incorporating abrasive particles with different charges that can selectively interact with different film types. The positive charge particles effectively polish oxide films, while negative charge particles effectively polish nitride films, allowing a single slurry to perform multiple polishing functions simultaneously.
2Manufacturing precision
If low solid content slurry is used, then surface scratches are reduced, but polishing rate decreases
Solution Approach 1:
The patent changes the charge parameter of the abrasive particles by using colloidal silica with both positive and negative charges. This parameter change allows the particles to maintain effective polishing capability at low solid content (0.1-5 wt%), reducing surface scratches while preserving adequate polishing rates through enhanced charge-film interactions.
3Productivity
If single charge abrasive particles are used, then slurry composition is simplified, but polishing selectivity for different films is insufficient
Solution Approach 1:
The patent uses composite abrasive particles with different charge characteristics to achieve selective polishing of different film types. The combination of positive and negative charge colloidal silica particles creates a composite system that can simultaneously target oxide, nitride, polysilicon, and copper films with appropriate polishing rates.
Solution Approach 2:
The slurry composition applies local quality by having different charge characteristics distributed within the same slurry. Positive charge particles preferentially interact with oxide films, while negative charge particles preferentially interact with nitride films, providing localized polishing effectiveness for different film types.
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 effectively secures polishing rates for both silicon oxide and silicon nitride films while maintaining a low solid content, reducing surface scratches, and ensuring high polishing performance across multiple film types.
Implementation Method 1
the wafer surface is polished by mechanical friction between abrasive particles in the slurry composition and surface protrusions of the pad
Implementation Method 2
chemical removal is performed by a chemical reaction between chemical components in the slurry composition and the wafer surface
Implementation Method 3
the wafer surface is polished by mechanical friction between abrasive particles in the slurry composition
Data Source
AI summary
Provided is a slurry composition for chemical mechanical polishing (CMP) including two types of colloidal silica abrasive particles, a pH buffer, and a pH adjuster, in which the two types of colloidal silica abrasive particles include first colloidal silica abrasive particles having a neutral charge and second colloidal silica abrasive particles having a negative charge.