Bias Supply Impedance Feedback for Consistent Plasma Etching
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Solution Overview
Problem
Current techniques for controlling bias power in plasma processing rely on inaccurate assumptions or predictions of capacitances in the plasma chamber, leading to unpredictable ion trajectories and inconsistent etching profiles.
Innovation Solution
A system that dynamically controls the ramp voltage of the bias supply based on real-time impedance indicators, using sensors to monitor power reflection and adjust the bias waveform to maintain consistent ion energy levels without relying on chamber capacitance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If bias power control relies on assumptions or predictions of chamber capacitances, then the control system is simple, but the etching profile consistency deteriorates
Solution Approach 1:
The system measures actual chamber impedance during plasma processing and uses this real-time feedback to adjust bias power delivery. The controller continuously monitors impedance changes and modifies the bias waveform accordingly, replacing static capacitance assumptions with dynamic measurement-based control, thereby achieving consistent etching profiles across different chambers.
2Manufacturing precision
If real-time impedance measurement is implemented, then etching profile consistency improves, but device complexity increases
Solution Approach 1:
The plasma chamber itself provides the measurement signal through its inherent impedance characteristics during normal operation. The system uses the existing plasma discharge and power delivery infrastructure to extract impedance information, eliminating the need for separate measurement devices or additional sensors, thus reducing overall system complexity while achieving precise control.
3Manufacturing precision
If chamber impedance is dynamically measured and used for control, then processing accuracy improves, but processing time increases
Solution Approach 1:
The impedance measurement and bias power adjustment occur continuously during plasma processing without interrupting the etching operation. The controller monitors impedance in real-time and makes continuous adjustments to the bias waveform, ensuring that processing accuracy is maintained throughout the entire process without requiring separate measurement or calibration steps that would consume additional time.
Data Source
AI summary
A generator to provide a source waveform, and a controller configured to receive a signal indicative of power reflected to the generator, receive timing information from a bias supply, and provide a report of the impedance based upon the bias waveform information.