Ceramic Susceptor RF Rod Structure for Lower Impedance Heating
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Solution Overview
Problem
The increasing RF power and frequency in plasma CVD processes lead to higher impedance in RF rods, resulting in heat generation and deterioration of connection parts, such as melting, burning, or degradation, which affects the process results.
Innovation Solution
The RF rod is designed with a root portion, a core portion, and an outer circumferential portion made of a non-magnetic material, such as brass, titanium, or stainless steel, which covers the outer circumference of the core portion, reducing impedance and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF power and frequency are increased to improve plasma CVD process efficiency, then productivity is improved, but impedance of the RF rod increases causing heat generation and connection part deterioration
Solution Approach 1:
The RF rod is divided into multiple sections with different materials: a magnetic material section (Ni or Kovar) and a non-magnetic material section (W, Mo, or Cu). This segmentation allows each section to perform its specific function - the magnetic section provides mechanical strength and magnetic properties for plasma generation, while the non-magnetic section reduces impedance and heat generation at high frequencies, thereby resolving the contradiction between productivity improvement and reliability maintenance.
Solution Approach 2:
The RF rod uses a composite structure combining magnetic and non-magnetic materials. The magnetic material (Ni/Kovar) provides necessary mechanical and magnetic properties, while the non-magnetic material (W/Mo/Cu) reduces impedance and heat generation. This composite approach enables the system to handle higher RF power and frequency for improved productivity while maintaining connection part durability through reduced thermal stress and impedance losses.
2Productivity
If RF frequency is increased to improve process speed, then productivity is improved, but heat generation due to skin effect increases causing connection part deterioration
Solution Approach 1:
The RF rod is segmented into magnetic and non-magnetic material sections. The non-magnetic material section (W, Mo, or Cu) specifically addresses the skin effect problem at high frequencies by providing lower impedance and reduced heat generation, allowing the system to operate at higher frequencies for improved productivity without excessive temperature rise that would damage connection parts.
Solution Approach 2:
The invention changes the material parameters of the RF rod by introducing non-magnetic materials with different electrical and thermal properties. These parameter changes reduce the skin effect and impedance at high frequencies, enabling higher operating frequencies for improved productivity while controlling heat generation to prevent connection part deterioration.
3Reliability
If impedance of RF rod is reduced to minimize heat generation, then reliability is improved, but device complexity increases due to multi-material construction
Solution Approach 1:
The RF rod is divided into two functional sections with different materials, each optimized for specific requirements. This segmentation achieves reliable heat generation control through appropriate material selection while keeping the structural complexity manageable through a clear, functional division rather than a complex multi-component assembly.
Solution Approach 2:
The composite material structure combines magnetic and non-magnetic materials in a straightforward configuration. This approach achieves reliable impedance and heat generation control through material properties while maintaining relatively simple device complexity through a direct, functional composite construction rather than a complex multi-component system.
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 effectively reduces the impedance of the RF rod, minimizing heat generation and preventing deterioration of connection parts, thereby improving the reliability and efficiency of the plasma CVD process.
Implementation Method 1
due to the skin effect which becomes more pronounced as the frequency increases, the impedance of the RF rod continues to increase
Implementation Method 2
RF is applied from the plasma upper electrode 104 to generate plasma as represented by arrows in FIG. 12, and the RF current flows to the ground 108 through the RF rod 120
Data Source
AI summary
There is provided a ceramic susceptor including: a ceramic plate having a first surface and a second surface and having an RF electrode and a heater electrode embedded therein; a cylindrical ceramic shaft attached to the second surface and having an internal space; an RF rod having one end connected to the RF electrode and having another end extending from the second surface; and a heater rod having one end connected to the heater electrode and having another end extending from the second surface and extending through the internal space. The RF rod includes: a root portion including an end portion to be fitted into a terminal hole formed in the second surface of the ceramic plate; a core portion extending from the root portion in a direction away from the second surface; and a non-magnetic material-made outer circumferential portion covering an outer circumference of the core portion.