Pulsed RF Inductive Plasma System for High-Pressure Processing
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Solution Overview
Problem
High gas pressure plasma sources face challenges in achieving high throughput and controlling thermal damage due to frequent collisions between plasma particles and gas molecules, limiting their application to high temperature materials processing, and the difficulty in coupling RF power for repetitive pulsed operations.
Innovation Solution
A pulsed RF inductive plasma system that operates at high gas pressures (1 torr to 2000 torr) with controlled pulse duration (10 μs-10 ms) and repetition rates (1 Hz to 1,000 Hz) using high power RF generation from solid state switches, allowing efficient energy transfer and reduced thermal effects, coupled with advanced resonance circuits and antenna designs for efficient power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high gas pressure plasma sources operate at high input power levels to increase reactive species generation, then throughput is improved, but gas temperature increases to 2000 C or higher causing thermal damage
Solution Approach 1:
The patent applies pulsed RF power delivery instead of continuous power, creating periodic plasma generation cycles. The plasma is generated in repeated short bursts at high power levels, allowing the gas to be processed in pulses rather than continuous exposure. This periodic action enables high reactive species generation during each pulse while providing cooling intervals between pulses, thus achieving high throughput without sustained high temperatures that would cause thermal damage.
Solution Approach 2:
The system dynamically adjusts the RF power delivery by controlling pulse width, duty cycle, and repetition rate. This dynamic control allows optimization of the balance between reactive species generation (during plasma pulses) and thermal management (during off periods), enabling the system to adapt to different processing requirements and prevent thermal damage while maintaining high productivity.
2Quantity of substance
If RF power is coupled continuously to maintain plasma at high gas pressure, then plasma density is maintained, but thermal damage to components increases
Solution Approach 1:
The patent implements periodic RF power coupling where plasma is generated in repeated pulses rather than continuously. During each pulse, high plasma density is achieved for effective processing. Between pulses, the plasma extinguishes and the system cools down, preventing cumulative thermal damage to reactor components. This periodic on-off cycling maintains average plasma density sufficient for processing while avoiding continuous thermal loading.
Solution Approach 2:
The pulsed plasma system maintains continuous useful action by ensuring that the cumulative effect of repeated pulses achieves the required processing throughput. The high plasma density during each pulse, combined with appropriate pulse repetition rates, ensures that material processing continues effectively over time without interruption, while the off periods between pulses prevent thermal damage.
3Temperature
If fast gas flow is used to limit gas heating time, then thermal damage is reduced, but system complexity and cost increase due to expensive gas recovery systems
Solution Approach 1:
The pulsed plasma system inherently limits gas heating time by generating plasma only during short pulses rather than continuously. The gas is exposed to heating only during the plasma pulse duration, which is a small fraction of the total cycle time. This time-limited heating approach reduces the need for complex fast gas flow systems and expensive gas recovery infrastructure, as the thermal load is naturally constrained by the pulsed operation mode.
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 approach enables high plasma reactivity and density, reducing thermal damage to components while maintaining high reaction throughput, suitable for industrial-scale nanotechnology and materials processing without the need for complex cooling systems.
Implementation Method 1
RF inductive plasma generation at high gas pressures
Implementation Method 2
efficient energy transfer and reduced thermal effects
Data Source
AI summary
A pulsed radio frequency inductive plasma source and method are provided. The source may generate plasma at gas pressures from 1 torr to 2000 torr. By utilizing high power RF generation from fast solid state switches such as Insulated-Gate Bipolar Transistor (IGBT) combined with the resonance circuit, large inductive voltages can be applied to RF antennas to allow rapid gas breakdown from 1-100 μs. After initial breakdown, the same set of switches or an additional rf pulsed power systems are utilized to deliver large amount of rf power, between 10 kW to 10 MW, to the plasmas during the pulse duration of 10 μs-10 ms. In addition, several methods and apparatus for controlling the pulse power delivery, timing gas and materials supply, constructing reactor and substrate structure, and operating pumping system and plasma activated reactive materials delivery system will be disclosed. When combined with the pulsed plasma generation, these apparatuses and the methods can greatly improve the applicability and the efficacy of the industrial plasma processing.