Makeup air handling unit in semiconductor fabrication building and method for cleaning air using the same
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Solution Overview
Problem
The semiconductor fabrication industry faces challenges in minimizing particle contamination on wafers due to the accumulation of organic, metal, and other particles during the manufacturing process of integrated circuits, which compromises the functional integrity of the devices as the size of circuit elements decreases, necessitating effective air purification in cleanroom environments.
Innovation Solution
A makeup air handling unit is designed to purify outside air using a filtration system that includes hollow fibers with porous layers, capturing unwanted substances and airborne molecular contaminants, and a series of filtration modules to ensure stringent control over contaminants and environmental parameters, ensuring clean air distribution within semiconductor fabrication buildings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional filtration systems are used in cleanroom environments, then air flow is maintained, but particle contamination and organic contaminants accumulate on wafers
Solution Approach 1:
The patent employs hollow fiber membranes with controlled pore sizes to physically trap particles and contaminants while allowing air flow. The porous structure of the filtration media enables separation of clean air from contaminated air, directly addressing the contradiction by removing harmful particles without compromising air flow necessary for cleanroom operation.
Solution Approach 2:
The filtration system combines multiple filtration layers and materials (including HEPA filters and hollow fiber membranes) to create a composite filtration approach. This multi-material system enhances contamination removal effectiveness while maintaining appropriate air flow characteristics, resolving the contradiction between cleanliness and air flow requirements.
2Productivity
If makeup air is introduced from outside the cleanroom, then air circulation is maintained, but airborne molecular contaminants are brought into the environment
Solution Approach 1:
The system performs preliminary filtration of outside air through multiple filtration stages (pre-filters, HEPA filters, and hollow fiber membranes) before the air is introduced into the cleanroom environment. This preliminary action removes contaminants in advance, allowing air circulation to be maintained without introducing harmful airborne molecular contaminants into the controlled environment.
3Reliability
If filtration efficiency is increased to remove more contaminants, then air purity is improved, but pressure drop and energy consumption increase
Solution Approach 1:
The filtration system is segmented into multiple stages with progressively finer filtration (pre-filtration, HEPA filtration, and hollow fiber membrane filtration). This segmentation distributes the filtration load across multiple components, allowing each stage to operate at optimal efficiency without creating excessive pressure drop, thereby reducing overall energy consumption while maintaining high air purity.
Solution Approach 2:
The system utilizes hollow fiber membranes with specifically engineered pore size parameters optimized for removing airborne molecular contaminants. By carefully selecting and controlling the pore size parameter, the system achieves high filtration efficiency for contaminants while minimizing resistance to air flow, thus reducing the energy required to maintain air circulation.
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 effectively removes contaminants and improves air purity, meeting or exceeding cleanroom standards, thereby reducing particle contamination and enhancing the yield and integrity of semiconductor products by maintaining a controlled environment.
Implementation Method 1
a porous layer is formed on an inner wall of each of the hollow fibers. The porous layer is configured to remove airborne molecular contaminants having fewer than 5 carbon atoms
Data Source
AI summary
A semiconductor fabrication building is provided. The semiconductor fabrication building includes an ambient control surrounding and a makeup air handling unit configured to supply clean air to the ambient control surrounding. The makeup air handling unit includes a housing having an air inlet and an air outlet. The makeup air handling unit also includes a first filtration module positioned in the housing. The first filtration module includes a number of hollow fibers configured to guide air to flow from the air inlet to the air outlet. A porous layer is formed at an inner wall of each of the hollow fibers to filter airborne molecular contamination (AMC) having a selected size.