Microwave Plasma Power Control for Stable Multi-Carrier Pulsing
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Solution Overview
Problem
Existing plasma processing apparatuses lack precise control over pulse-modulated power of microwaves with bandwidth for multi-carriers, leading to power fluctuations and inefficiencies in plasma processing.
Innovation Solution
A plasma processing apparatus with a microwave output device that includes a power supply unit capable of pulse-modulating power with specific center frequency, bandwidth, and carrier pitch, using directional couplers and a measurement unit to control high-level and low-level power based on set values, ensuring the pulse on time is longer than the power fluctuation cycle, thereby stabilizing the power waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pulse modulation is applied to microwave power for plasma processing, then plasma processing efficiency is improved, but power fluctuation occurs leading to imprecise power control
Solution Approach 1:
The patent applies periodic pulse modulation to the microwave power supply, switching between high-level and low-level power in controlled cycles. This periodic action enables precise control of average power delivered to the plasma, improving processing efficiency while maintaining controllability through defined pulse width and duty cycle parameters.
Solution Approach 2:
The patent implements a feedback control system using directional couplers to monitor forward and reflected power, with a measurement unit that detects actual power levels. This feedback mechanism allows the system to compensate for power fluctuations and maintain precise power control despite pulse modulation, directly addressing the contradiction between improved efficiency and maintained precision.
2Adaptability or versatility
If microwave bandwidth is increased for multi-carrier operation, then plasma processing versatility is improved, but power fluctuation cycle becomes significant affecting control accuracy
Solution Approach 1:
The patent synchronizes the pulse modulation period with the power fluctuation cycle characteristic of multi-carrier microwave operation. By setting the pulse width and period appropriately, the system captures complete fluctuation cycles during each pulse, enabling accurate measurement and control of average power across the bandwidth, thus maintaining measurement precision while enabling versatile multi-carrier operation.
Solution Approach 2:
The feedback system measures both forward and reflected power during pulse periods and calculates actual delivered power to the plasma. This feedback mechanism compensates for power fluctuations inherent in broadband multi-carrier operation, maintaining measurement accuracy and enabling versatile plasma processing across different frequency and power conditions.
3Manufacturing precision
If pulse frequency and duty ratio are adjusted for optimal plasma processing, then processing quality is improved, but power control complexity increases
Solution Approach 1:
The patent uses periodic pulse modulation with adjustable pulse width and duty cycle to control average power delivery to the plasma. By varying these periodic parameters, the system can optimize plasma processing quality for different applications while maintaining a relatively simple control architecture based on standard pulse generation circuits.
Solution Approach 2:
The patent implements a universal control system that manages multiple functions through integrated circuitry: pulse generation, duty cycle control, power measurement via directional couplers, and feedback regulation. This multi-functional approach allows the system to achieve precise power and quality control without proportionally increasing device complexity, as a single control unit handles multiple tasks.
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 configuration allows for precise control of pulse-modulated power, suppressing power fluctuations and enhancing the stability and precision of plasma processing by synchronizing the pulse modulation with the power feedback loop.
Implementation Method 1
a power supply unit configured to output power for exciting a gas supplied to an inside of the chamber body
Implementation Method 2
Japanese Patent Application Publication No. 2019-36482 discloses a plasma processing apparatus using a microwave
Data Source
AI summary
There is provided a plasma processing apparatus. The apparatus comprises: a chamber body; and a power supply unit configured to output power for exciting a gas supplied to an inside of the chamber body. The power supply unit supplies, as power having a center frequency, a bandwidth, and a carrier pitch respectively corresponding to a set frequency, a set bandwidth, and a set carrier pitch that are indicated by a controller, power which is pulse-modulated so as to be a pulse frequency, a duty ratio, a high level, and a low level respectively corresponding to a set pulse frequency, a set duty ratio, a high-level set power, and a low-level set power indicated by the controller, and in which a pulse on time determined by the set pulse frequency and the set duty ratio is longer than a power fluctuation cycle of the power having the bandwidth.