Gate Valve Double Sealing for Hot Wall Vacuum Integrity
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Solution Overview
Problem
Existing gate valve units in semiconductor manufacturing fail to maintain high vacuum pressures due to heat-induced deterioration of sealing members, allowing air to penetrate and disrupt the vacuum environment, especially in hot wall chambers where temperatures exceed room temperature.
Innovation Solution
A double sealing structure with communicating holes between the first and second sealing members, allowing the gap between them to be vacuum-evacuated, preventing air from entering the chamber with a higher vacuum requirement, and using a bellows heater to maintain the integrity of the sealing system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sealing member is used in the gate valve unit, then the device complexity is reduced, but the sealing function deteriorates when heated, allowing air to penetrate
Solution Approach 1:
The sealing member is divided into multiple segments (first sealing member and second sealing member) that can independently function. Each sealing member is positioned at different locations within the gate valve unit, allowing them to seal different interfaces separately, thereby maintaining reliable sealing without excessive complexity
Solution Approach 2:
The first sealing member and second sealing member are arranged in a nested configuration where one sealing member is positioned inside or adjacent to the other. This nested arrangement allows both sealing members to be integrated within the gate valve unit without significantly increasing the overall size or complexity of the sealing structure
2Productivity
If the gate valve unit is placed in a hot wall chamber, then the substrate processing capability is improved, but the heat transmission deteriorates the sealing function of the sealing member
Solution Approach 1:
Different regions of the gate valve unit are designed with different thermal properties. The first sealing member is positioned in a region less affected by heat transmission, while the second sealing member is positioned closer to the hot wall chamber interface. This local differentiation allows the sealing members to maintain their sealing function despite the hot wall environment
Solution Approach 2:
The gate valve unit incorporates multiple sealing members made of different materials or with different thermal resistance properties. This composite sealing approach allows the system to withstand the thermal environment of the hot wall chamber while maintaining effective sealing at both the chamber and transfer chamber interfaces
3Reliability
If the vacuum degree is increased to lower than 10^-7 Torr, then the vacuum quality is improved, but the air penetration through the heated sealing member increases
Solution Approach 1:
The sealing function is segmented into multiple independent sealing members, so that if one sealing member allows some air penetration at ultra-high vacuum levels, the other sealing members provide additional barrier layers to maintain the required vacuum quality
Solution Approach 2:
The gate valve unit is designed with multiple sealing members as a preventive measure against air penetration. This redundant sealing arrangement cushions against the harmful effect of air leakage, ensuring that even if one sealing member deteriorates or allows penetration, the vacuum quality below 10^-7 Torr is maintained
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
Effectively maintains the predetermined vacuum pressure in high vacuum chambers by preventing air ingress through the sealing members, even when heated, ensuring consistent processing conditions across different temperature environments.
Implementation Method 1
the communicating holes allow a gap between the first sealing member and the second sealing member to communicate with an internal space of the housing
Data Source
AI summary
A substrate processing device includes a depressurizable hot wall chamber having a sidewall with a temperature which becomes higher than room temperature and a first substrate transferring port provided in the sidewall, a depressurizable transfer chamber having a transfer arm mechanism and a second substrate transferring port, and a gate valve unit provided between the hot wall chamber and the transfer chamber. The gate valve unit includes: a housing having a sidewall provided with communicating holes, a first housing substrate transferring port, and a second housing substrate transferring port; a valve body which is elevatable in the housing; and a double sealing structure having a first sealing member and a second sealing member provided at an outer side of the first sealing member. The communicating holes communicate a gap between the first sealing member and the second sealing member with an internal space of the housing.