Post-CMP Cleaning Composition for Ceria Removal
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Solution Overview
Problem
Current methods for removing ceria particles from microelectronic devices are inefficient, as ceria-based slurries are difficult to remove due to oppositely charged zeta potentials with silicon oxide and silicon nitride surfaces, leading to residues that cause short circuits and increased electrical resistance, and existing wet cleaning formulations like dilute hydrofluoric acid etch silicon oxide and low-k dielectrics.
Innovation Solution
An aqueous removal composition comprising a nucleophile or reducing agent, surfactants, and complexing agents is used to break the cerium-oxygen bond, facilitating the removal of ceria particles and CMP contaminants from microelectronic devices without damaging underlying materials like silicon nitride or low-k dielectrics, with the surfactant preventing re-deposition and shifting reaction equilibria to enhance removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dilute hydrofluoric acid is used to remove ceria particles, then ceria particle removal efficiency is improved, but silicon oxide and low-k dielectric materials are etched and damaged
Solution Approach 1:
The patent changes the chemical parameters of the cleaning composition by using a non-fluoride-based formulation with specific pH range (2-10) and containing chelating agents, surfactants, and oxidizing agents to achieve ceria removal without etching silicon oxide and low-k dielectrics
Solution Approach 2:
The patent introduces intermediary substances including chelating agents that bind to ceria particles, surfactants that facilitate particle detachment, and oxidizing agents that convert ceria to more removable forms, enabling effective ceria removal through multiple intermediate chemical steps rather than direct acid etching
2Productivity
If ceria-based slurry is used for CMP polishing, then polishing speed for insulator is improved and STI pattern planarization is achieved with minimal oxide erosion, but ceria particles are difficult to remove from STI structures
Solution Approach 1:
The patent converts the harmful adhesive property of ceria particles (which causes residues) into a beneficial removal mechanism by using chemical compositions that specifically target and break the ceria-surface bond through chelation and oxidation, transforming the persistent residue problem into an effective removal opportunity
Solution Approach 2:
The patent uses a composite cleaning composition containing multiple functional ingredients (chelating agents, surfactants, oxidizing agents, and buffers) that work synergistically to address different aspects of ceria particle removal: chelation for particle detachment, oxidation for particle transformation, and surfactant action for particle suspension and prevention of re-deposition
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 removes at least 85% of ceria particles and CMP contaminants, preventing damage to silicon nitride, low-k dielectrics, and tungsten-containing layers, thereby improving the cleanliness and reliability of microelectronic devices.
Implementation Method 1
a nucleophile or reducing agent, effective in facilitating the removal of cerium
Implementation Method 2
complexing agents
Implementation Method 3
certain surfactants
Data Source
AI summary
A removal composition and process for cleaning post-chemical mechanical polishing (CMP) contaminants and ceria particles from a microelectronic device having said particles and contaminants thereon. The composition achieves highly efficacious removal of the ceria particles and CMP by-product contaminant material from the surface of the microelectronic device without compromising the low-k dielectric, silicon nitride, or tungsten-containing materials.