Phosphonium Polymer CMP Slurries for Low-Dishing Tungsten Planarization
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Solution Overview
Problem
Current chemical mechanical planarization (CMP) slurries face challenges in minimizing dishing and erosion during the polishing of tungsten layers, which are critical for maintaining planarity and functionality in semiconductor devices.
Innovation Solution
The development of CMP slurries incorporating phosphonium-based polymers or copolymers, which electrostatically interact with the tungsten surface to inhibit excessive removal and reduce dishing and erosion, is introduced. These polymers are synthesized with specific structures and used in combination with abrasives, oxidizing agents, and other additives to control the polishing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP slurries are used for polishing tungsten layers, then tungsten removal is achieved, but dishing and erosion occur that compromise planarity
Solution Approach 1:
Phosphonium-based polymers serve as intermediary substances that adsorb onto the tungsten surface during CMP processing. These polymers mediate between the abrasive particles and the tungsten surface, controlling the removal process to prevent both excessive removal (dishing) and insufficient removal (erosion), thereby maintaining planarity while achieving desired tungsten removal rates
Solution Approach 2:
The invention modifies the chemical composition parameters of the CMP slurry by incorporating phosphonium-based polymers with specific molecular weights and concentrations. This parameter change alters the interaction mechanisms between slurry components and tungsten surface, enabling controlled removal that prevents dishing and erosion while maintaining manufacturing precision
2Productivity
If aggressive polishing is applied to remove tungsten, then removal rate increases, but dishing worsens
Solution Approach 1:
The phosphonium-based polymers provide a feedback mechanism by adsorbing onto the tungsten surface and modulating the removal rate in real-time. As polishing progresses and the surface becomes smoother, the polymer adsorption increases, automatically reducing the removal rate to prevent dishing, thus enabling sustained high productivity without shape degradation
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 use of phosphonium-based polymers in CMP slurries effectively reduces dishing and erosion while maintaining desirable tungsten removal rates, thereby improving the planarity and reliability of semiconductor wafers.
Implementation Method 1
phosphonium-based polymers or copolymers, which electrostatically interact with the tungsten surface to inhibit excessive removal
Implementation Method 2
The slurry initiates the polishing process by chemically reacting with the film being polished
Data Source
AI summary
Synthesis of phosphonium based polymers is disclosed. Chemical Mechanical Planarization (CMP) slurries comprise abrasives; activator; oxidizing agent; additive comprising phosphonium based polymers; and water. The use of the synthesized phosphonium based polymers in the CMP slurries reduces dishing and erosion in highly selective tungsten slurries.