EFEM Dry Gas Flow Barrier for Wafer Transfer Humidity Control
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Solution Overview
Problem
In semiconductor fabrication facilities, high relative humidity during wafer transfer can lead to wafer contamination and defects due to reactions between moisture and residual materials on the wafers.
Innovation Solution
A humidity control device is integrated into the equipment front end module (EFEM) of the semiconductor processing tool, which uses a gas flow device to direct low humidity gas across the access opening where wafers are transferred, effectively limiting humidity ingress into the wafer carrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high relative humidity is present during wafer transfer, then wafer transfer operations can proceed normally, but wafer contamination and defects occur due to reactions between moisture and residual materials on the wafers
Solution Approach 1:
A gas flow device introduces a stream of dry gas (nitrogen or filtered air) between the ambient environment and the wafer carrier interior. This gas stream acts as an intermediary barrier that physically blocks humid ambient air from entering the wafer carrier, thereby protecting wafers from moisture-related contamination without interfering with normal wafer transfer operations
Solution Approach 2:
The system uses pneumatic flow of dry gas to control the humidity environment. By regulating the gas flow rate and pressure, the system creates a protective atmosphere at the access opening that prevents humid air ingress while maintaining normal operational access for wafer transfer
2Reliability
If a gas flow device is used to control humidity, then wafer contamination is reduced, but gas consumption increases
Solution Approach 1:
Instead of filling the entire wafer carrier interior with dry gas, the system applies the gas flow locally only at the access opening where humidity ingress occurs. This localized approach maintains effective humidity control at the critical interface while minimizing overall gas consumption
Solution Approach 2:
The system uses a partial gas flow that is sufficient to block humid air intrusion at the access opening but does not exceed what is necessary. By optimizing the flow rate to the minimum effective level, the system achieves humidity control without excessive gas consumption
3Object-affected harmful factors
If large amounts of low humidity gas are used to control humidity, then humidity ingress is prevented, but safety issues arise related to nitrogen displacement in the cleanroom
Solution Approach 1:
The system uses a partial gas flow that is sufficient to block humid air intrusion but does not create excessive gas accumulation. By maintaining the flow at an optimized level, the system prevents both humidity ingress and nitrogen displacement hazards
Solution Approach 2:
The system incorporates humidity sensing and flow regulation that adjusts gas delivery based on actual humidity conditions. This feedback mechanism ensures adequate protection against humidity ingress while preventing excessive gas consumption that could lead to nitrogen displacement
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 solution significantly reduces the relative humidity within the wafer carrier, minimizing the risk of wafer contamination and defects, while also reducing the consumption of low humidity gas and avoiding potential safety issues related to nitrogen displacement in the cleanroom.
Implementation Method 1
A humidity control device is integrated into the equipment front end module (EFEM) of the semiconductor processing tool, which uses a gas flow device to direct low humidity gas across the access opening where wafers are transferred
Data Source
AI summary
A load port receives a wafer carrier. An equipment front end module (EFEM) transfers semiconductor wafers to and from the wafer carrier via an access opening of a housing of the EFEM, and also transfers wafers to and from a semiconductor processing or characterization tool. A gas flow device disposed inside the housing of the EFEM is connected to receive a low humidity gas having relative humidity of 10% or less, and is positioned to flow the received low humidity gas across the access opening. A saturated pressure layer of the gas flow device has a permeability for the low humidity gas that increases with increasing distance from a gas inlet edge of the saturated pressure layer, for example due to holes of varying diameter and/or density passing through the saturated pressure layer. A filter layer of the gas flow device uniformizes the gas exiting the saturated pressure layer.