Wafer Placement Table Cooling Base Electrode Design
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Solution Overview
Problem
The existing wafer placement tables are inefficient in drawing ions to the focus ring due to the embedding of the focus ring attracting electrode in the outer peripheral part of the ceramic base, leading to increased reactance and reduced ion drawing efficiency, particularly with lower frequency bias radio frequencies.
Innovation Solution
A wafer placement table design with a ceramic base having an outer peripheral part less than or equal to 1 mm in thickness without an electrode, where the cooling base, which is made of metal, acts as the focus ring attracting electrode, source radio-frequency electrode, and bias radio-frequency electrode, reducing reactance and enhancing ion drawing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the focus ring attracting electrode is embedded in the outer peripheral part of the ceramic base, then the focus ring can be electrostatically attracted, but the thickness of the outer peripheral part must be increased, which increases the distance to the cooling base and increases reactance, reducing ion drawing efficiency
Solution Approach 1:
The patent merges the focus ring attracting electrode function with the cooling base by making the cooling base itself electrically conductive and capable of serving as the attracting electrode. This eliminates the need for a separate embedded electrode in the ceramic base, thereby reducing the thickness requirement and reactance while maintaining the electrostatic attraction function.
Solution Approach 2:
The cooling base is designed to serve multiple functions simultaneously: it provides thermal cooling, acts as the focus ring attracting electrode, and serves as the bias radio-frequency electrode. This multi-functionality eliminates the need for separate components and reduces overall system complexity and reactance.
2Ease of manufacture
If the outer peripheral part of the ceramic base is thickened to embed the focus ring attracting electrode, then the electrode can be properly positioned, but the distance to the cooling base increases, increasing reactance and reducing bias radio-frequency effectiveness
Solution Approach 1:
The patent combines the electrode positioning function directly into the cooling base structure, eliminating the need for thickening the ceramic base. The cooling base itself provides the electrical connection and positioning, achieving proper electrode placement without increasing distance or reactance.
3Reliability
If the focus ring attracting electrode is embedded in the ceramic base, then the structure is established, but the outer peripheral part requires increased thickness, increasing overall device complexity and reducing manufacturing efficiency
Solution Approach 1:
The patent merges multiple functional components into the cooling base, which serves as both the thermal management component and the electrical attracting electrode. This reduces the number of separate components and simplifies the overall structure while maintaining structural stability.
Solution Approach 2:
The cooling base is designed to perform multiple functions simultaneously - thermal cooling, electrostatic attraction, and radio-frequency conduction - eliminating the need for separate embedded electrodes and reducing structural complexity in the ceramic base.
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 configuration efficiently attracts the focus ring and draws ions using the bias radio-frequency voltage, while also simplifying the structure and reducing thermal reactance, allowing for effective plasma generation and heat management during wafer processing.
Implementation Method 1
When a focus ring attracting voltage is applied to the cooling base, a focus ring is able to be electrostatically attracted to the focus ring placement surface
Implementation Method 2
When a bias radio-frequency voltage is applied to the cooling base, the reactance between the cooling base and the focus ring placement surface reduces, so it is possible to efficiently draw ions to the focus ring by the bias radio-frequency voltage
Implementation Method 3
A first radio-frequency power supply that generates a source radio frequency for generating plasma and a second radio-frequency power supply that generates a bias radio frequency for drawing ions to a wafer are connected to the cooling base
Data Source
AI summary
A wafer placement table includes a ceramic base, a cooling base, and a bonding layer. The ceramic base includes an outer peripheral part having an annular focus ring placement surface on an outer peripheral side of a central part having a circular wafer placement surface. The cooling base contains metal. The bonding layer bonds the ceramic base with the cooling base. The outer peripheral part of the ceramic base has a thickness of less than or equal to 1 mm and does not incorporate an electrode.