Wafer Placement Table Structure for Concentrated Plasma Density
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Solution Overview
Problem
Wafer placement tables with a cooling substrate of greater diameter than the ceramic substrate generate plasma outside the wafer area, leading to reduced plasma density over the ceramic substrate, as the larger area generates plasma that is not utilized in wafer processing.
Innovation Solution
A wafer placement table design where the support substrate, with a greater diameter than the conductive substrate, is electrically insulated, preventing plasma generation in the radial extension area and thus concentrating plasma density over the ceramic substrate, and using metal joining layers for cost-effective manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the cooling substrate has a greater diameter than the ceramic substrate, then the cooling substrate can provide sufficient cooling area, but plasma is generated in regions extending out of the wafer area, reducing plasma density over the ceramic substrate
Solution Approach 1:
The support substrate is segmented into two functional zones: a central conductive substrate region for plasma generation and a peripheral insulating mounting flange region for mechanical support. This segmentation allows the cooling substrate to maintain its larger diameter for adequate cooling while preventing plasma generation in the peripheral mounting flange area, thereby concentrating plasma density over the ceramic substrate.
Solution Approach 2:
Different regions of the support substrate are assigned different electrical properties: the central conductive substrate region is made conductive to enable plasma generation, while the peripheral mounting flange region is made electrically insulating to suppress plasma generation. This local differentiation of electrical quality allows the system to maintain both adequate cooling area and high plasma density over the wafer region.
2Strength
If the cooling substrate has a greater diameter than the ceramic substrate, then structural support is improved, but plasma generation occurs in non-wafer regions, wasting energy
Solution Approach 1:
The support substrate is divided into a conductive central region and an insulating peripheral mounting flange. This segmentation enables the peripheral region to provide structural support and mounting functionality without generating plasma, thereby eliminating energy waste in non-wafer regions while maintaining adequate structural strength.
Solution Approach 2:
The peripheral region of the support substrate, which would otherwise generate wasted plasma, is converted into an electrically insulating mounting flange. This transformation converts the harmful effect of wasted plasma generation into a beneficial mounting structure that provides both mechanical support and plasma suppression, improving energy efficiency.
3Quantity of substance
If the support substrate is made of insulating material, then plasma generation is suppressed in the mounting flange region, but manufacturing complexity increases
Solution Approach 1:
The support substrate integrates multiple functions into a single component: the central conductive substrate region serves as both a structural support element and a plasma generation electrode, while the peripheral insulating mounting flange provides both mechanical mounting functionality and plasma suppression. This merging of functions reduces the need for additional separate components and simplifies the overall manufacturing process.
Solution Approach 2:
The support substrate is designed as a multi-functional component where different regions perform different functions: structural support, electrical insulation, plasma generation, and mounting. This universality allows a single component to replace what would otherwise require multiple separate parts, thereby reducing manufacturing complexity despite the sophisticated functional requirements.
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
This design increases plasma density directly above the ceramic substrate by suppressing plasma generation in the radial extension area, enhancing the efficiency of plasma-based wafer processing while reducing manufacturing costs.
Implementation Method 1
a high-frequency voltage may be applied to the cooling substrate to generate plasma
Implementation Method 2
conductive substrate disposed adjacent to a lower surface of the ceramic substrate, having the same diameter as the ceramic substrate
Implementation Method 3
conductive cooling substrate have been known. The ceramic substrate has a wafer placement surface and contains an electrode therein, and the cooling substrate is disposed adjacent to a lower surface of the ceramic substrate
Data Source
AI summary
A wafer placement table includes a ceramic substrate having a wafer placement surface on an upper surface thereof and containing an electrode therein; a conductive substrate disposed adjacent to a lower surface of the ceramic substrate, serving also as a plasma generating electrode, and having the same diameter as the ceramic substrate; a support substrate disposed adjacent to a lower surface of the conductive substrate, having a greater diameter than the conductive substrate, and electrically insulated from the conductive substrate; and a mounting flange constituting a part of the support substrate and radially extending out of the conductive substrate.