MHz RF Generator Power Reflection Reduction
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Solution Overview
Problem
In plasma processing systems, a significant amount of power is reflected back to the megahertz radio frequency (MHz) generator from the plasma chamber, leading to inefficiency and increased costs due to the need for larger generators to compensate for the lost power, particularly when operating in conjunction with kilohertz radio frequency (kHz) generators.
Innovation Solution
Implementing active and passive power control methods within the MHz RF generator, including the use of high-speed power controllers and impedance matching networks, to adjust power supply based on reflection coefficients, and modifying RF cables and capacitors to optimize power delivery, thereby reducing power reflection and increasing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a megahertz RF generator operates in conjunction with a kilohertz RF generator in a plasma chamber, then plasma processing capability is enhanced, but power reflection increases significantly reducing delivery efficiency
Solution Approach 1:
The patent implements dynamic power adjustment by modulating the megahertz RF generator's output power in synchrony with the kilohertz RF generator's operational cycle. A controller monitors the kilohertz generator's state and dynamically adjusts the megahertz generator's power level to minimize reflections during high-reflection phases while maintaining processing effectiveness during low-reflection phases.
Solution Approach 2:
The patent changes the power parameter of the megahertz RF generator based on the operational state of the kilohertz RF generator. By adjusting power levels in response to plasma impedance variations caused by kilohertz operation, the system optimizes power transfer efficiency and reduces reflected power while maintaining plasma processing capability.
2Power
If larger megahertz RF generators are used to compensate for power loss, then sufficient processing power is maintained, but system cost and complexity increase
Solution Approach 1:
The patent employs a feedback control system that monitors power reflection levels and plasma conditions, then adjusts the megahertz RF generator's power output accordingly. This closed-loop control ensures that the minimum necessary power is delivered to maintain processing effectiveness, eliminating the need for oversized generators and reducing overall system cost and complexity.
Solution Approach 2:
The patent utilizes periodic power modulation synchronized with the kilohertz RF generator's cycle. By delivering power in optimized periodic pulses rather than continuous high power, the system maintains effective plasma processing while using a smaller, more cost-effective megahertz RF generator.
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 proposed solution significantly reduces power reflection, enhancing the efficiency of power delivery to the plasma chamber, allowing for the same processing output with smaller MHz RF generators, thus lowering operational and capital costs.
Implementation Method 1
a capacitor of an impedance matching network is controlled, and/or an RF cable that is coupled to the MHz RF generator is modified such that the supplied power of the MHz RF generator is high when a power reflection coefficient at an output of the MHz RF generator is low
Implementation Method 2
A plasma tool is used to process a wafer. For example, a dielectric etch tool is used for depositing materials on or for etching the wafer. The plasma tool includes multiple radio frequency (RF) generators.
Data Source
AI summary
Systems and methods for tuning a radio frequency (RF) generator are described. One of the methods includes supplying, by a high frequency RF generator, a high frequency RF signal to the IMN. The method includes accessing a plurality of measurement values of a variable measured at an output of the high frequency RF generator to generate a parameter. The variable is measured during a plurality of cycles of operation of a low frequency RF generator. The measurement values are associated with a plurality of values of power supplied by the high frequency RF generator. The method includes determining, for one of the cycles, a value of a frequency of the high frequency RF generator and a value of a factor associated with a shunt circuit of the IMN for which there is an increase in efficiency in power delivered by the high frequency RF generator.