Virtual Impedance Auto Matching for Plasma Chamber
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Solution Overview
Problem
In plasma processing, initial incorrect selection of vacuum variable capacitor positions can lead to unmatchable areas, increasing auto matching time and initial reflected wave power, thereby affecting process stability and continuity.
Innovation Solution
A virtual impedance auto matching method is implemented, where an impedance matcher is connected to a computing device to perform virtual matching before actual connection, optimizing initial preset positions of vacuum variable capacitors based on process type and steps, and adjusting positions to ensure impedance matching within specified ranges, thereby reducing auto matching time and suppressing initial reflected wave power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If initial preset positions of vacuum variable capacitors are not optimized, then the system can operate without additional complexity, but unmatchable areas occur and process stability deteriorates
Solution Approach 1:
The patent performs virtual impedance matching in advance before actual plasma processing to determine optimal initial preset positions of vacuum variable capacitors. This preliminary action ensures that when the actual process starts, the capacitors are already positioned correctly, avoiding unmatchable areas and ensuring process stability without requiring complex real-time adjustments during production.
Solution Approach 2:
The patent creates a virtual model that copies the electrical characteristics of the actual plasma processing system. By performing impedance matching on this virtual model, the system can determine optimal capacitor positions without affecting the actual hardware. This copying approach allows for safe, repeated virtual experiments to optimize parameters before applying them to the real system.
2Productivity
If conventional impedance matching is used without virtual matching, then the system structure remains simple, but auto matching time increases and productivity decreases
Solution Approach 1:
The patent performs virtual impedance matching in advance to determine optimal initial preset positions of vacuum variable capacitors for different process conditions. By pre-calculating these positions, the actual impedance matching time during plasma processing is significantly reduced, as the capacitors start from an optimized position rather than requiring full adjustment range traversal.
Solution Approach 2:
The patent dynamically adjusts the initial preset positions of vacuum variable capacitors based on different process types, recipes, and steps. Instead of using fixed positions, the system selects from pre-determined optimal positions that are specific to each process condition, enabling faster convergence to the matching state while adapting to varying operational requirements.
3Object-affected harmful factors
If initial preset positions of vacuum variable capacitors are not optimized, then the system operation remains simple, but initial reflected wave power increases and causes damage
Solution Approach 1:
The patent performs virtual impedance matching in advance to determine optimal initial preset positions of vacuum variable capacitors. By pre-positioning the capacitors at these optimized locations, the system minimizes initial reflected wave power when plasma processing starts, preventing damage to the RF generator while avoiding complex real-time control during the actual process.
Data Source
AI summary
A virtual impedance auto matching method includes (a) deciding an input parameter of an RF generator and a load condition parameter of a plasma chamber, (b) applying an RF ON signal to an impedance matcher, (c) determining whether initial preset positions of a load vacuum variable capacitor and a tuning vacuum variable capacitor constituting the impedance matcher are within a matching range, (d) applying the RF OFF signal to the impedance matcher and generating an alarm signal indicating deviation from the matching range, when step (c) is not satisfied, (e) starting matching by operating the impedance matcher when step (c) is satisfied, and (f) deciding the initial preset positions of the load vacuum variable capacitor and the tuning vacuum variable capacitor by analyzing a magnitude error and a phase error with respect to 50+j0 according to an impedance change, when the matching is completed.