Plasma Probe Spacer Design for O-Ring Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ion flux probe designs in plasma processing chambers face issues such as chemical contamination, accelerated o-ring degradation, mechanical misalignment, and slow thermal equilibrium due to the use of quartz rings and poor thermal conductivity, leading to reduced system throughput and increased maintenance costs.
Innovation Solution
The design incorporates a high aspect ratio vacuum gap and a sharply angled plasma-to-o-ring path to extend o-ring life, eliminates direct plasma exposure to dielectric materials, and improves thermal conductivity by using a spacer and thermal contact ring to achieve accurate positioning and rapid thermal equilibrium between the ion flux probe and the upper electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a quartz ring is used to electrically insulate the probe head from the upper electrode, then electrical insulation is achieved, but chemical contamination occurs during plasma processing
Solution Approach 1:
The patent removes the quartz ring spacer that caused chemical contamination. Instead, the probe head is electrically insulated from the upper electrode by using an insulating coating applied directly to the probe head surface, eliminating the separate quartz ring component that was eroding and contaminating the plasma process.
Solution Approach 2:
The patent introduces an insulating coating as an intermediary layer between the probe head and the plasma environment. This coating provides electrical insulation without the chemical erosion issues of quartz, acting as a stable mediator that prevents harmful chemical interactions while maintaining electrical isolation.
2Reliability
If a quartz ring is used for electrical insulation, then insulation is provided, but the o-ring degrades accelerated due to direct plasma exposure
Solution Approach 1:
The patent changes the geometric arrangement by using a sharply angled plasma-to-o-ring path instead of a direct line-of-sight exposure. The o-ring is positioned such that plasma must travel along a angled path to reach it, reducing direct plasma flux and thereby extending o-ring service life while maintaining electrical insulation through the coated probe head.
3Measurement precision
If the probe head is positioned close to the upper electrode for accurate measurement, then measurement accuracy is improved, but thermal equilibrium is slow due to poor thermal conductivity
Solution Approach 1:
The patent changes the thermal parameter by using a probe head made of a material with high thermal conductivity. This allows the probe head to rapidly achieve thermal equilibrium with the upper electrode even when positioned in close proximity, eliminating the time delay while maintaining the measurement accuracy benefits of close positioning.
4Adaptability or versatility
If mechanical tolerance and thermal expansion are accommodated with gaps, then mechanical flexibility is achieved, but direct plasma exposure to the o-ring occurs
Solution Approach 1:
The patent resolves the contradiction by changing the plasma path geometry to a sharply angled trajectory. The gap is maintained for mechanical flexibility and thermal expansion, but the o-ring is positioned such that plasma must follow an angled path to reach it, effectively blocking direct line-of-sight plasma exposure while preserving the necessary mechanical clearance.
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 enhances the longevity of the o-ring, reduces contamination, ensures accurate measurements, and decreases system downtime by preventing chemical loading and improving thermal equilibrium, thereby increasing plasma processing efficiency and reducing maintenance needs.
Implementation Method 1
improves thermal conductivity by using a spacer and thermal contact ring to achieve accurate positioning and rapid thermal equilibrium between the ion flux probe and the upper electrode
Data Source
AI summary
An arrangement for measuring process parameters within a processing chamber is provided. The arrangement includes a probe arrangement disposed in an opening of an upper electrode. Probe arrangement includes a probe head, which includes a head portion and a flange portion. The arrangement also includes an o-ring disposed between the upper electrode and the flange portion. The arrangement further includes a spacer made of an electrically insulative material positioned between the head portion and the opening of the upper electrode to prevent the probe arrangement from touching the upper electrode. The spacer includes a disk portion configured for supporting an underside of the flange portion. The spacer also includes a hollow cylindrical portion configured to encircle the head portion. The spacer forms a right-angled path between the o-ring and an opening to the processing chamber to prevent direct line-of-sight path between the o-ring and the opening to the processing chamber.