Slit Valve Spacer Design for Semiconductor Vacuum Chambers
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Solution Overview
Problem
Slit valve doors in vacuum equipment for semiconductor manufacturing experience premature wear and contamination due to dynamic metal-to-metal contact and exposure to corrosive gases, leading to inconsistent sealing and particle generation.
Innovation Solution
A spacer is used to maintain a consistent gap between the slit valve door and the slit valve body, reducing exposure to corrosive gases and preventing over-compression, combined with a labyrinth design to increase the path length of plasma particles and a recess to direct gas flow, thereby minimizing contamination and extending seal life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resilient seal (O-ring) is used for sealing the slit valve door, then sealing effectiveness is improved, but the seal experiences dynamic metal-to-metal contact and rubbing that generates particles and shortens its life-span
Solution Approach 1:
A metal insert is introduced as an intermediary component between the slit valve door and the chamber. This insert provides a sealing surface that prevents direct metal-to-metal contact between the door and chamber walls, thereby eliminating the generation of metal particles while maintaining effective sealing through the resilient O-ring.
2Reliability
If the gap between the slit valve door and chamber is reduced to eliminate metal-to-metal contact, then seal protection is improved, but the seal may become over-compressed which also degrades it
Solution Approach 1:
The gap dimension between the slit valve door and chamber is precisely controlled and optimized. By adjusting this geometric parameter to a specific value, the design achieves a balance that prevents both metal-to-metal contact and over-compression of the seal, thereby extending seal life while maintaining sealing effectiveness.
3Reliability
If traditional adjustment and calibration methods are used to control gap size, then seal protection can be achieved, but the process is tedious and requires manual intervention
Solution Approach 1:
The slit valve door assembly is designed with built-in features such as pre-set spacers or mechanically constrained positioning elements that automatically maintain the optimal gap size. This self-adjusting mechanism eliminates the need for tedious manual adjustment and calibration, allowing the system to self-regulate the gap for proper seal protection.
4Productivity
If the slit valve door is frequently opened and closed for wafer transfer, then productivity is improved, but the O-ring experiences continuous rubbing and abrading that shortens its life-span
Solution Approach 1:
The metal insert serves as a mediator that absorbs the wear and rubbing during frequent door operations. By providing a durable sealing surface that prevents direct contact between the O-ring and metal surfaces, the insert protects the O-ring from degradation even under continuous cycling conditions, thereby extending its service life while maintaining high productivity.
Data Source
AI summary
A spacer for maintaining a gap between a slit valve door and a sealing surface of a slit valve body. The spacer may be located on an outer ambient side of the slit valve away from any corrosive gasses that may exist in the chamber. The spacer may be attached to the slit valve door partially in a depression therein, and may be integral with the seal.