Load Port Door Clearance Geometry for Gas Flow Stability
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Solution Overview
Problem
In semiconductor manufacturing, existing load port apparatuses face challenges in maintaining a stable gas flow and preventing dust entry when the pressure difference between the mini-environment and the exterior space is small, particularly with larger wafers, leading to turbulence and instability in air flow.
Innovation Solution
A load port apparatus with a door that creates a clearance with a varying slit width, designed to maintain a constant gas flow rate by tapering the slit edges to reduce turbulence, ensuring the flow is stable even with small pressure differences, and featuring a fan to manage air flow within the mini-environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a door is used to close the opening portion in the load port apparatus, then dust entry into the mini-environment is prevented, but turbulence occurs in the air flow and gas flow stability deteriorates when pressure difference is small
Solution Approach 1:
The door is designed with a non-uniform clearance distribution, creating different gap sizes at different locations. The clearance is larger at the upper portion and smaller at the lower portion, optimizing flow characteristics locally to prevent turbulence while maintaining dust prevention
Solution Approach 2:
The solution transitions from considering only the vertical dimension of the door to incorporating the horizontal dimension by creating an asymmetric clearance pattern around the door perimeter, thereby controlling flow in multiple dimensions simultaneously
2Loss of energy
If the pressure difference between mini-environment and exterior space is reduced, then energy consumption is lowered, but dust prevention capability and flow stability deteriorate
Solution Approach 1:
The invention changes the geometric parameters of the door clearance, specifically creating a non-uniform distribution where the gap size varies around the door perimeter. This allows effective dust prevention with minimal pressure difference by optimizing the flow path geometry
3Object-affected harmful factors
If the door clearance is reduced to prevent dust, then dust entry is minimized, but air flow turbulence increases and flow uniformity deteriorates
Solution Approach 1:
Different portions of the door clearance are designed with different gap sizes to serve different functions: smaller gaps prevent dust entry while larger gaps in specific regions maintain flow uniformity and reduce turbulence
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 stabilizes gas flow and reduces dust deposition on wafers, enhancing the yield rate in semiconductor manufacturing by maintaining a consistent flow rate and preventing dust entry, even with larger wafers.
Implementation Method 1
a chamber (3) inside which the pressure is kept higher than the pressure of its exterior space
Data Source
AI summary
In a load port apparatus, a clearance is formed between an inner circumferential surface of an opening of the chamber and an outer circumferential surface of a door. The area of the clearance between the plate and the opening portion on a plane flush with an interior side of the chamber is larger than the area of the clearance between the plate and the opening portion on a plane flush with the exterior of the chamber. A fan located at an upper side of the chamber generates a first flow of air in the downward direction. The clearance generates a second flow of air from the interior of the chamber to the exterior of the chamber. The second flow of air is generated by the difference in the area of the interior cross section of the clearance and area of the exterior cross section of the clearance.