Variable Reactance RF Matching for Dynamic Plasma Loads
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Solution Overview
Problem
Conventional RF power systems face challenges in impedance matching for dynamic plasma loads in processes like semiconductor manufacturing and flat panel displays, particularly in achieving high-speed impedance matching within microseconds to tens of microseconds, especially during atomic layer deposition and through silicon via processes, due to the limitations of existing impedance matching methods.
Innovation Solution
A variable reactance impedance matching network is introduced between a variable frequency RF power source and a load, where the variation of capacitance or inductance of the reactive component is controlled based on the difference between the target driving frequency and the current frequency, using specific conditions and weighting functions to minimize reflection power and achieve impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable element impedance matching network is used, then impedance matching can be performed on a wide range of load impedance, but matching time increases to hundreds of milliseconds to several seconds
Solution Approach 1:
The patent replaces the mechanical motor-driven variable reactive elements with electronically controllable variable reactive elements. This substitution eliminates the mechanical inertia and driving speed limitations of motors, enabling rapid adjustment of reactance values. The electronic control system can change capacitance or inductance values within microseconds to milliseconds, achieving both wide impedance matching range and fast response time required for dynamic plasma loads.
2Loss of time
If frequency tuning is used for impedance matching, then matching time is very short (microseconds to milliseconds), but the frequency variable range is limited to about 10 percent
Solution Approach 1:
The patent segments the impedance matching function into two independent parts: frequency adjustment and reactance adjustment. The frequency variable RF power source handles frequency tuning within its variable range, while the variable reactive component handles reactance adjustment. This segmentation allows the system to achieve fast response through frequency tuning while extending the effective matching range through additional reactance control, overcoming the limitation of narrow frequency variable range.
3Device complexity
If conventional impedance matching methods are used, then system complexity is reduced, but high-speed impedance matching within microseconds to tens of microseconds cannot be achieved
Solution Approach 1:
The patent merges the frequency variable RF power source and the variable reactive component into a coordinated impedance matching system. The control unit integrates control signals for both frequency adjustment and reactance adjustment, enabling simultaneous or coordinated operation of both mechanisms. This merging allows the system to achieve high-speed impedance matching within microseconds to tens of microseconds by combining the fast frequency tuning capability with the extended reactance adjustment range, while maintaining relatively simple system architecture through unified control.
Data Source
AI summary
An impedance matching device and an impedance matching method. A variable reactance impedance matching network is disposed between a variable frequency RF power source varying a driving frequency and a load. An impedance matching method of the variable reactance impedance matching network includes controlling variation amount of capacitance or reactance of a variable reactive component of the impedance matching network as a function of a difference between a target driving frequency ft and the driving frequency.