Helical Electrode Dual-Frequency Plasma Stability
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Solution Overview
Problem
Plasma processing devices face instability due to mode jump regions when using inductive discharge, leading to reduced etching speed and increased processing time, especially at higher frequencies like 13.56 MHz, where F radical light emission intensity is lower compared to 2 MHz.
Innovation Solution
A plasma processing device with a helical second electrode configured to receive two types of AC voltages simultaneously, one at 2 MHz and another at 13.56 MHz, allowing the device to remain in a stable inductive discharge region by avoiding the mode jump region, ensuring consistent etching characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If AC voltage at 2 MHz is applied to the helical electrode, then F radical light emission intensity is high and etching speed is fast, but mode jump region causes discharge instability and requires manual adjustment time
Solution Approach 1:
The patent applies periodic AC voltages at two different frequencies (2 MHz and 13.56 MHz) alternately or simultaneously to the helical electrode. This periodic application of multiple frequencies allows the system to operate in the inductive discharge region with high F radical intensity while avoiding the mode jump region instability, achieving both high etching speed and discharge stability.
2Reliability
If AC voltage at 13.56 MHz is applied to the helical electrode, then discharge is stable without mode jump region, but F radical light emission intensity is about half that of 2 MHz and etching speed is halved
Solution Approach 1:
The patent merges the advantages of both 2 MHz and 13.56 MHz AC voltages by applying them together to the helical electrode. The combination allows the system to maintain the discharge stability of 13.56 MHz while achieving the high F radical light emission intensity and etching speed of 2 MHz, effectively combining the benefits of both frequencies.
Solution Approach 2:
The patent changes the frequency parameter from a single frequency system to a dual frequency system. By introducing a second frequency component (13.56 MHz) to the existing 2 MHz operation, the system transforms its operational characteristics to achieve both stability and high etching speed simultaneously.
3Reliability
If manual adjustment is performed in the inductive discharge region at 2 MHz, then discharge stability is achieved, but processing time increases by about 1 minute
Solution Approach 1:
The patent performs preliminary action by pre-configuring the dual frequency power supply system to automatically maintain optimal discharge conditions. The system is set up in advance to apply both 2 MHz and 13.56 MHz voltages, which eliminates the need for manual adjustments during operation, thereby achieving discharge stability without the time loss associated with manual intervention.
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 device achieves stable and efficient etching characteristics in the inductive discharge region without the influence of mode jump regions, resulting in improved etching speed and reduced processing time, similar to the 2 MHz frequency, while maintaining high F radical light emission intensity.
Implementation Method 1
a second high frequency power supply and a third high frequency power supply are configured to be electrically connected to the second electrode, the second high frequency power supply being configured to apply an AC voltage of a second frequency to the second electrode, the third high frequency power supply being configured to apply an AC voltage of a third frequency to the second electrode
Implementation Method 2
a plasma processing device capable of stably using an excellent etching characteristic in an inductive discharge region
Implementation Method 3
Gas introducing unit configured to introduce a fluorine-containing process gas from a gas introducing port into the chamber
Data Source
AI summary
A plasma processing device includes: a chamber; a flat-plate-shaped first electrode; a first high frequency power supply; a helical second electrode disposed outside the chamber and disposed to face the first electrode with a quartz plate forming an upper lid of the chamber therebetween; and a gas introducing unit, in which a second high frequency power supply and a third high frequency power supply are configured to be electrically connected to the second electrode, the second high frequency power supply being configured to apply an AC voltage of a second frequency to the second electrode, the third high frequency power supply being configured to apply an AC voltage of a third frequency to the second electrode, and the third frequency being higher than the second frequency; and two types of AC voltages are configured to be simultaneously applied.