Semiconductor Laser Plasma Ignition Without Low-Pressure Arcing
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Solution Overview
Problem
Existing plasma generating systems face challenges in quickly igniting plasma without causing undesirable arcing, especially at low gas flow rates and pressures, which affects the uniformity and productivity of plasma processing.
Innovation Solution
A method using a semiconductor laser to irradiate process gas in a plasma generating system, applying high-frequency power to a coil or electrode, and stopping the laser emission once plasma is ignited, facilitating quick ignition without arcing through multiphoton ionization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high pressure is applied in the chamber to quickly ignite plasma, then plasma ignition speed is improved, but plasma processing uniformity deteriorates
Solution Approach 1:
The invention changes the physical state parameters of the process gas by applying laser irradiation to increase local temperature and energy, enabling plasma ignition at low pressure without compromising processing uniformity. This resolves the contradiction by finding an alternative parameter (laser energy input) to achieve quick ignition without increasing chamber pressure.
Solution Approach 2:
A semiconductor laser is introduced as an intermediary device to facilitate plasma ignition. The laser provides the necessary energy to initiate plasma formation in the process gas, acting as a mediator that enables ignition at low pressure conditions while maintaining uniform plasma processing characteristics.
2Loss of time
If high power laser is used to ignite plasma, then plasma ignition speed is improved, but arcing and contamination occur
Solution Approach 1:
The invention uses a low-power semiconductor laser instead of high-power excimer lasers, employing a more economical and controllable light source that achieves plasma ignition without causing harmful arcing or contamination. The semiconductor laser provides sufficient energy for ignition while its lower power output prevents the generation of harmful effects.
Solution Approach 2:
The laser irradiation is applied in a controlled, periodic manner to initiate plasma formation, then stopped once ignition occurs. This periodic action allows plasma ignition to be achieved without continuous high-power exposure that would cause arcing and contamination.
3Power
If high frequency power is applied to coil or electrode, then plasma generation is achieved, but ignition difficulty persists at low pressure
Solution Approach 1:
Laser irradiation is applied as a preliminary action before or during the application of high frequency power to the coil or electrode. This preliminary energy input prepares the process gas for plasma formation, making subsequent plasma generation reliable even at low pressure conditions where direct high frequency power application would fail.
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 allows for rapid plasma ignition without arcing, reducing costs and preventing overheating, while maintaining plasma processing efficiency and uniformity.
Implementation Method 1
The reason why the plasma can still be ignited with a low power semiconductor laser is assumed to be that the process gas is subjected to multiphoton ionization.
Implementation Method 2
In a case in which the plasma generating system includes a coil, inductively coupled plasma is generated by applying a high frequency power to the coil.
Data Source
Figure 1
Figure 2~3B
Figure 4A~4B
AI summary
Provided is a method of igniting a plasma to quickly ignite a plasma without causing undesirable arcing. The method of igniting a plasma according to the present invention includes: a supplying step of supplying a process gas into a chamber 1 provided in a plasma generating system; an igniting step of igniting a plasma by irradiating the process gas supplied into the chamber with laser light L emitted from a semiconductor laser 10 and applying a high frequency power to a coil 2 or an electrode 91 for generating plasma provided in the plasma generating system; and a stopping step of stopping emission of the laser light from the semiconductor laser after the plasma is ignited. Preferably, the coil is a cylindrical coil, and in the igniting step, the laser light is obliquely irradiated from above the cylindrical coil toward below the cylindrical coil.