Wafer Placement Table Gas Passage Layout to Prevent Discharge
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Solution Overview
Problem
Existing wafer placement tables experience issues with electrical discharge in gas intermediate passages due to potential gradients, leading to wafer charring and particle generation, while also suffering from inadequate heat dissipation around gas supply passages.
Innovation Solution
A wafer placement table design with a ceramic plate, an electrically conductive plate, and a gas intermediate passage embedded in an electrically conductive bonding layer, where the number of gas introduction passages is fewer than gas supply passages, ensuring equal potential across the gas intermediate passage and preventing electrical discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If gas supply passages pass through the cooling plate in the up and down direction, then gas can be supplied to the wafer, but hot spots are formed around the openings due to insufficient heat dissipation
Solution Approach 1:
The patent transitions from vertical gas supply passages (up-down direction) to a horizontal gas intermediate passage configuration. Gas is supplied horizontally through the intermediate passage and then distributed vertically to multiple supply passages, changing the primary dimension of gas flow from vertical to horizontal to avoid concentrated heat exposure at single opening points.
Solution Approach 2:
The gas supply system is segmented into a gas intermediate passage and multiple gas supply passages. The intermediate passage distributes gas to multiple separate supply passages, dispersing the gas introduction points and preventing concentration of heat at a single location, thereby reducing hot spot formation.
2Productivity
If a gas intermediate passage is provided parallel to the wafer placement surface, then soaking performance is improved, but electrical discharge may occur in the passage due to potential gradient
Solution Approach 1:
The gas intermediate passage is positioned between two electrodes at the same potential (both at ground potential or both at RF potential), creating an equipotential environment. This eliminates the potential gradient that would otherwise cause electrical discharge, while still allowing gas to be distributed along the passage to improve wafer soaking performance.
Solution Approach 2:
The gas intermediate passage acts as an intermediary structure that mediates between the conflicting requirements of gas distribution and electrical isolation. By positioning it in a region where both electrodes meet (at the same potential), it serves as a safe conduit for gas flow without becoming a site for electrical discharge.
3Ease of operation
If multiple gas introduction passages are provided through the cooling plate, then gas distribution is improved, but heat dissipation performance deteriorates
Solution Approach 1:
The gas distribution function is segmented between the gas intermediate passage (horizontal distribution) and multiple gas supply passages (vertical distribution to wafer). This segmentation allows gas to be introduced through fewer points in the cooling plate while still achieving widespread distribution, minimizing the number of openings that would compromise heat dissipation.
Solution Approach 2:
Gas distribution is achieved by adding a horizontal dimension through the intermediate passage, rather than only using vertical openings through the cooling plate. This allows gas to travel horizontally to multiple distribution points before reaching the wafer, reducing the need for multiple vertical openings that would harm heat dissipation.
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 design enhances wafer soaking performance by improving heat dissipation and preventing electrical discharge, facilitating efficient gas distribution to the wafer surface.
Implementation Method 1
The upper surface of the gas intermediate passage is the electrically conductive bonding layer, the lower surface of the gas intermediate passage is the electrically conductive plate, and the electrically conductive bonding layer and the electrically conductive plate are in contact with each other and have the same potential.
Implementation Method 2
a metal cooling plate bonded to the lower surface of the ceramic plate... hot spots tend to be formed around the openings of the gas supply passages on the wafer placement surface because of insufficient dissipation of heat
Data Source
AI summary
A wafer placement table includes: a ceramic plate having a wafer placement surface on its upper surface and incorporating an electrode; an electrically conductive plate provided on a lower surface side of the ceramic plate; an electrically conductive bonding layer that bonds the ceramic plate with the electrically conductive plate; a gas intermediate passage embedded in the electrically conductive bonding layer or provided at an interface between the electrically conductive bonding layer and the electrically conductive plate; a plurality of gas supply passages extending from the gas intermediate passage through the electrically conductive bonding layer and the ceramic plate to the wafer placement surface; and a gas introduction passage provided so as to extend through the electrically conductive plate and communicate with the gas intermediate passage, the number of the gas introduction passages being smaller than the number of the gas supply passages communicating with the gas intermediate passage.