Adaptive Periodic Waveform Controller for Plasma RF Stability
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Solution Overview
Problem
Existing RF generator systems for plasma chambers face challenges in efficiently controlling and stabilizing RF output across multiple plasma electrodes, leading to suboptimal performance and increased complexity in maintaining identical RF outputs.
Innovation Solution
A power output generation system that includes a repeating setpoint generator module, closed-loop module, adjusting module, and mixer module, which selectively varies setpoints and adjusts power input based on proportional-integral control and frequency adjustments to optimize RF output to plasma electrodes, using a power amplifier and driver control module to manage distortion and impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple RF generators are employed to service larger surface areas, then the treatment capability is improved, but the complexity of maintaining identical RF outputs increases
Solution Approach 1:
The patent implements a feedback control system where the controller continuously monitors the RF output from multiple generators and adjusts each generator's output to maintain identical performance. The system measures actual RF outputs and uses this feedback to dynamically adjust generator parameters, ensuring consistency across all plasma electrodes despite variations in load conditions or electrode characteristics.
Solution Approach 2:
The controller dynamically adjusts operating parameters (such as power level, frequency, or phase) of each RF generator based on real-time measurements and predetermined patterns. By changing these parameters adaptively, the system maintains identical RF outputs from multiple generators even when servicing larger surface areas with multiple plasma electrodes.
2Device complexity
If conventional RF control systems are used, then the system structure is simple, but the tracking of setpoints and response characteristics are suboptimal
Solution Approach 1:
The control system transitions from static to dynamic operation by continuously adjusting RF output parameters in real-time. The controller modifies generator settings dynamically based on measured outputs and predetermined patterns, enabling precise tracking of setpoints and improved response characteristics while maintaining manageable system complexity through automated control.
Solution Approach 2:
The system applies periodic adjustments to RF generator outputs based on predetermined patterns that repeat during successive time intervals. This periodic control action enables the system to anticipate and compensate for variations, improving setpoint tracking and response characteristics without requiring overly complex continuous control mechanisms.
3Productivity
If RF output is increased to improve productivity, then the treatment speed is improved, but the stability and precision of RF delivery deteriorates
Solution Approach 1:
The feedback control system continuously monitors RF output parameters and adjusts generator settings to maintain stability even at higher power levels. By measuring actual outputs and comparing them to desired setpoints, the system compensates for variations and maintains precise control, enabling improved productivity without sacrificing the stability or precision of RF delivery to plasma electrodes.
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 system improves the tracking of setpoints by the RF output, reduces overshoot and settling time, and enhances response characteristics, allowing for more precise and efficient RF power delivery to plasma electrodes, even in systems with nonlinear loads.
Implementation Method 1
A power amplifier applies an output power to a load
Implementation Method 2
The RF output may be applied to, for example, a plasma electrode of a plasma chamber. Plasma chambers may be used in thin film manufacturing systems
Data Source
AI summary
A repeating setpoint generator module selectively varies a setpoint for an output parameter according to a predetermined pattern that repeats during successive time intervals. A closed-loop module, during a first one of the time intervals, generates N closed-loop values based on N differences between (i) N values of the setpoint at N times during the first one of the time intervals and (ii) N measurements of the output parameter at the N times during the first one of the time intervals, respectively. An adjusting module, during the first one of the time intervals, generates N adjustment values based on N differences between (i) N values of the setpoint at the N times during a second one of the time intervals and (ii) N measurements of the output parameter at the N times during the second one of the time intervals, respectively.