Tunable CMP Removal Rates via Dissolved Oxygen Control
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Solution Overview
Problem
Current chemical-mechanical polishing (CMP) processes lack tunable removal rates and selectivities for materials like polysilicon/si(100), silicon dioxide, copper, and silicon nitride, which are crucial for semiconductor device fabrication.
Innovation Solution
A method and system utilizing a chemical slurry or solution with varying dissolved oxygen content, combined with ceria-based dispersions and specific additives, to achieve tunable removal rates and selectivities by controlling the reactive Ce3+ species on the ceria abrasive surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional CMP processes use standard chemical slurries, then material removal occurs, but removal rates and selectivities cannot be tuned
Solution Approach 1:
The patent applies parameter changes by systematically varying the dissolved oxygen content in the chemical slurry to control the removal rates and selectivities of different materials. By adjusting the oxygen concentration as a key parameter, the process achieves tunable performance for polysilicon, silicon dioxide, copper, and silicon nitride removal, transforming a fixed-process CMP into an adaptable one.
Solution Approach 2:
The patent utilizes dissolved oxygen as a strong oxidant to enhance the chemical reaction mechanisms during CMP. The oxygen content is controlled to accelerate oxidation reactions that facilitate material removal, particularly for metals like copper and silicon-based materials, thereby enabling tunable removal rates through oxidative chemistry.
2Productivity
If high dissolved oxygen content is used in the slurry, then removal rate of polysilicon and silicon dioxide increases, but selectivity over copper may be reduced
Solution Approach 1:
The patent applies dynamics by making the dissolved oxygen content variable rather than fixed. The oxygen concentration is dynamically adjusted based on the specific polishing requirements - increased when high removal rates of polysilicon/silicon dioxide are needed, and controlled or reduced when copper selectivity is the priority, enabling adaptive process optimization.
Solution Approach 2:
The patent changes the dissolved oxygen parameter to control the chemical reactivity toward different materials. By modulating oxygen levels, the process selectively enhances or suppresses removal rates of specific materials, achieving the desired balance between productivity and selectivity for different polishing scenarios.
3Productivity
If pH is adjusted to optimize removal rate, then material removal efficiency improves, but control over selectivity becomes difficult
Solution Approach 1:
The patent introduces another dimension of control by adding dissolved oxygen content as an independent parameter alongside pH adjustment. Instead of relying solely on pH for both removal rate and selectivity control, the process uses oxygen content to independently tune selectivity while pH manages overall reactivity, creating a two-dimensional control space that resolves the trade-off between efficiency and precision.
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
This approach allows for precise control of removal rates and selectivities of polysilicon/si(100), silicon dioxide, and silicon nitride, enhancing the CMP process by adjusting dissolved oxygen levels and pH, thereby optimizing material removal during semiconductor fabrication.
Implementation Method 1
tunable removal rates and selectivities using a chemical slurry and/or solution with varying dissolved oxygen content
Implementation Method 2
controlling the reactive Ce3+ species on the ceria abrasive surface
Implementation Method 3
The abrasive scrapes the material to remove it
Data Source
AI summary
A method and system for tunable removal rates and selectivity of materials during chemical-mechanical polishing using a chemical slurry or solution with increased dissolved oxygen content. The slurry can optionally include additives to improve removal rate and/or selectivity. Further selectivity can be obtained by varying the concentration and type of abrasives in the slurry, using lower operating pressure, using different pads, or using other additives in the dispersion at specific pH values.