Grinding Liquid Filtration and Mixing for Wafer Scratch Prevention
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Solution Overview
Problem
Existing grinding liquid preparation systems fail to effectively prevent impurities and shear stress, leading to coarse particles that can cause scratches on semiconductor wafers during chemical mechanical polishing, and lack real-time monitoring to address quality issues.
Innovation Solution
A system with a stock solution circulation tank for filtration, a maglev stirrer for reduced shear stress, and capacitive liquid level sensors for real-time monitoring, ensuring uniform and fine slurry particles by eliminating impurities and monitoring liquid quality at each stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple filters and circulation tanks are added to remove impurities and prevent particle combination, then the grinding liquid quality is improved, but the device complexity increases
Solution Approach 1:
The system divides the grinding liquid preparation into separate functional modules: a first circulation tank for stock solution filtration, a second circulation tank for grinding liquid filtration, and a mixing tank for slurry preparation. Each tank operates independently with its own pump and filter, allowing targeted quality control at different stages without requiring a single complex system to handle all requirements.
Solution Approach 2:
The patent introduces intermediary circulation tanks between the stock solution barrel and the mixing tank, and between the mixing tank and the grinding liquid supplying tank. These intermediate tanks serve as buffers that allow filtration and quality monitoring at each stage, preventing direct contamination while maintaining system flow.
2Productivity
If high-pressure transportation is used to deliver grinding liquid, then the productivity is improved, but coarse particles may pass through filters and cause scratches on wafers
Solution Approach 1:
The system performs filtration and quality control actions before the high-pressure transportation stage. The first and second circulation tanks filter the stock solution and grinding liquid respectively, removing coarse particles in advance. The mixing tank prepares the slurry with controlled particle size before it is pumped to the polishing device, ensuring that even if high pressure is applied during delivery, no scratches will occur.
3Reliability
If real-time monitoring of liquid quality at each stage is implemented, then the reliability is improved, but the device complexity and cost increase
Solution Approach 1:
The patent incorporates capacitive liquid level sensors in each tank (stock solution circulation tank, grinding liquid circulation tank, and mixing tank) to monitor liquid levels and detect abnormal conditions. This feedback mechanism allows real-time monitoring of liquid quality and quantity at each stage, enabling immediate detection of issues such as incorrect liquid levels or contamination, without requiring complex analytical instrumentation.
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 system ensures high-quality grinding liquid output by filtering impurities, reducing shear stress, and providing real-time monitoring, thereby maintaining optimal wafer grinding quality.
Implementation Method 1
the first pipeline being provided with a first filter and a first pump, and the first pipeline allowing the stock solution to flow out from the stock solution circulation tank, to be pressurized by the first pump, to be sent to the first filter
Implementation Method 2
the grinding liquid mixing tank is provided with a second pipeline and a maglev stirrer
Implementation Method 3
a plurality of capacitive liquid level sensors, the stock solution circulation tank, the grinding liquid mixing tank, and the grinding liquid supplying tank being all connected in parallel with one capacitive liquid level sensor
Data Source
AI summary
A grinding liquid mixing and supplying system comprises a stock solution barrel, a stock solution circulation tank, a grinding liquid mixing tank, a grinding liquid supplying tank, which are configured with pipelines that interconnect each other; and capacitive liquid level sensors connected in parallel with these tanks. The stock solution circulation tank is provided with a first pipeline, the first pipeline is provided with a first filter and a first pump, and the first pipeline allows the stock solution to flow out from the stock solution circulation tank, to be pressurized by the first pump, to be sent to the first filter, and to flow back, so as to be circulated and filtered. The capacitive liquid level sensor detects a liquid level and monitors whether the liquid is normal in the tanks, so as to maintain and ensure the output quality of the grinding liquid.