Plasma Processing Frequency Sweep for Reliable Ignition
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Solution Overview
Problem
In plasma processing, the resonance condition in a processing chamber can change due to dimensional errors, assembly errors, and deposits, making it difficult to generate plasma using a power frequency determined for a steady state without plasma, leading to unreliable plasma ignition.
Innovation Solution
A plasma processing apparatus that includes a frequency control unit to sweep the power frequency from a first frequency to a second frequency during plasma generation, ensuring reliable ignition by adjusting the frequency within a predetermined range, such as 2.4 GHz to 2.5 GHz, to match the changing resonance conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a power frequency determined for a steady state without plasma is used, then the device complexity is reduced, but plasma ignition reliability deteriorates due to resonance condition changes from dimensional errors, assembly errors, and deposits
Solution Approach 1:
The patent applies dynamics by transitioning from a static fixed frequency to a dynamic frequency sweep approach. The frequency control unit dynamically adjusts the power frequency across a range (e.g., 2.4 GHz to 2.5 GHz) during plasma ignition, allowing the system to adapt to varying resonance conditions caused by dimensional errors, assembly errors, and deposits in the processing chamber.
Solution Approach 2:
The patent implements parameter changes by varying the power frequency parameter during plasma ignition. Instead of using a single predetermined frequency, the system sweeps through a frequency range to identify and lock onto the resonant frequency that matches the actual chamber conditions, thereby improving plasma ignition reliability without significantly increasing device complexity.
2Ease of operation
If the frequency is fixed for steady state operation, then the ease of operation is improved, but plasma generation reliability worsens when resonance conditions change due to dimensional errors, assembly errors, and deposits
Solution Approach 1:
The patent applies preliminary action by performing a frequency sweep before plasma ignition to identify the resonant frequency. The frequency control unit automatically scans through a frequency range and determines the optimal frequency for plasma generation, preparing the system in advance for reliable plasma ignition without requiring manual frequency adjustment by the operator.
Solution Approach 2:
The system implements self-service through automatic frequency locking. Once the frequency sweep identifies the resonant frequency, the frequency control unit automatically locks onto and maintains this frequency for plasma generation, eliminating the need for continuous manual intervention and ensuring reliable plasma generation despite variations in chamber conditions.
3Reliability
If a frequency sweep from first frequency to second frequency is implemented, then plasma ignition reliability is improved, but the loss of time increases due to frequency sweeping process
Solution Approach 1:
The patent applies partial action by implementing a frequency sweep over a targeted frequency range rather than sweeping through all possible frequencies. The system sweeps through a predetermined range (e.g., 2.4 GHz to 2.5 GHz) that is likely to contain the resonant frequency, balancing the need for reliable plasma ignition with the constraint of minimizing ignition time.
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 reliably ignites plasma and improves reproducibility in plasma processing by ensuring the frequency coincides with the resonance frequency, maintaining plasma generation and enhancing the consistency of plasma exposure to the target object.
Implementation Method 1
a power supply unit configured to supply a power of a predetermined frequency band into the processing chamber to generate plasma of the processing gas in the processing chamber
Implementation Method 2
a frequency control unit configured to sweep a frequency of the power supplied into the processing chamber by the power supply unit from a first frequency to a second frequency at the time of generating the plasma of the processing gas in the processing chamber
Data Source
AI summary
A plasma processing apparatus comprises a processing chamber, a gas supply unit, a power supply unit and a frequency control unit. The processing chamber accommodates a target object. The gas supply unit supplies a processing gas into the processing chamber. The power supply unit supplies a power of a predetermined frequency band into the processing chamber to generate plasma of the processing gas in the processing chamber. The frequency control unit sweeps a frequency of the power supplied into the processing chamber by the power supply unit from a first frequency to a second frequency at the time of generating the plasma of the processing gas in the processing chamber.