Thermal Choke Rod Compression Joint for High-Temperature RF Connections
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Solution Overview
Problem
Existing electrical connectors for plasma enhanced chemical vapor deposition (PECVD) processes face challenges due to high power requirements, high ambient temperatures, and fragility of RF pedestal rod threads, leading to poor electrical contact and risk of thread damage.
Innovation Solution
A thermal choke rod with a tubular member and conically-shaped end region, featuring slits for radial compression and a threaded region for an annular cap, provides a strong clamping force for connecting RF sources to substrate supports in plasma processing systems, while minimizing heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded electrical connections are used, then electrical contact area is provided, but the contact area is poor and non-repeatable causing electrical resistive heating
Solution Approach 1:
The patent replaces the traditional threaded mechanical connection system with a compression-based mechanical system. The compression electrical connection mechanism uses axial compressive force to create reliable electrical contact between conductive elements, eliminating the thread engagement problems while maintaining electrical connectivity. This substitution of the connection mechanism resolves the issue of poor and non-repeatable contact areas.
2Strength
If light torque is applied to RF pedestal rod threads, then thread damage is avoided, but insufficient electrical contact is provided for high power connection
Solution Approach 1:
The patent eliminates the threaded connection system entirely and replaces it with a compression-based connection mechanism. The compression electrical connection device applies controlled axial compressive force to create reliable electrical contact without requiring thread engagement. This resolves the contradiction by providing sufficient contact pressure for high power connections while completely avoiding thread damage risks.
Solution Approach 2:
The patent changes the mechanical parameter from torque-based thread engagement to compression-based direct contact. By applying controlled compressive force along the axial direction, the system achieves both adequate contact pressure for high power transmission and avoidance of thread-related mechanical failures. This parameter change enables simultaneous achievement of thread integrity and electrical contact capability.
3Reliability
If conventional electrical connectors are used, then connection is provided, but they cannot function at temperatures above 150-200 degrees Celsius
Solution Approach 1:
The patent employs composite material construction for the compression electrical connection device. The device incorporates materials with high temperature resistance properties, including ceramic components and high-temperature stable conductive materials. This composite material approach enables the connector to maintain structural integrity and electrical functionality at temperatures exceeding 300 degrees Celsius, far beyond the capabilities of conventional connectors.
4Power
If high power RF connections are made, then power transmission is achieved, but heat is generated that exceeds component capabilities
Solution Approach 1:
The patent replaces traditional mechanical connections with a compression-based electrical connection system that is optimized for high power RF applications. The compression mechanism creates low-contact-resistance interfaces that minimize resistive heating during high power transmission. Combined with high-temperature resistant materials, this enables sustained operation at power levels that would otherwise generate excessive heat in conventional connections.
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 thermal choke rod ensures reliable high-power electrical connections by providing a secure mechanical and electrical interface, effectively isolating heat from sensitive components and maintaining conductivity even at elevated temperatures.
Implementation Method 1
an annular cap configured to fit over the first connector and reduce an inner diameter of the first connector upon contact with the conically-shaped end region
Implementation Method 2
The thermal choke rod is formed of a base material having a low thermal conductivity
Implementation Method 3
the base material is plated with a highly electrically conductive material
Data Source
AI summary
A thermal choke rod connecting a radio frequency source to a substrate support of a plasma processing system includes a tubular member having a first connector for connecting to an RF rod coupled to the substrate support and a second connector for connecting to an RF strap that couples to the RF source. A tubular segment extends between the first and second connectors. The first connector has a conically-shaped end region that tapers away from the inner surface thereof to an outer surface in a direction toward the tubular segment, and slits that extend for a prescribed distance from a terminal end of the first connector. The outer surface of the tubular segment has a threaded region for threaded engagement with an annular cap that fits over the first connector and reduces an inner diameter of the first connector upon contact with the conically-shaped end region of the first connector.