Plasma Bias Waveform Generator With Ripple-Controlled DC Current
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Solution Overview
Problem
Current plasma assisted processing technologies face challenges in achieving precise control over voltage waveforms for ion energy distribution due to resonance issues and inefficiencies in existing amplifiers, leading to undesired oscillations and reduced process control.
Innovation Solution
A voltage waveform generator with a common node, a voltage waveform generation circuit, and a current source that uses a first switch node connected through a physical inductor and a power supply with adjustable voltage nodes to minimize ripple and optimize DC current, allowing for faster convergence to the desired waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If slow switching speeds are used to suppress resonance excitation, then voltage ringing is reduced, but discharge time increases and process efficiency decreases
Solution Approach 1:
The patent introduces a damping resistance (or snubber) as an intermediary element to suppress voltage ringing caused by resonance. This mediator component absorbs the oscillatory energy in the LC circuit formed by reactor capacitance and interconnection inductance, preventing voltage instability while allowing faster switching speeds for improved process efficiency.
2Stability of the object's composition
If a damping resistance (snubber) is added to suppress voltage ringing, then voltage stability improves, but energy losses increase
Solution Approach 1:
The patent employs dynamic switching strategies where the damping resistance is activated only during specific phases of the voltage waveform when resonance suppression is needed. This dynamic approach maintains voltage stability while minimizing energy losses by keeping the damping element inactive during other operational phases.
3Adaptability or versatility
If wideband linear amplifiers are used for bias voltage generation, then waveform control flexibility improves, but generation efficiency decreases
Solution Approach 1:
The patent implements periodic switching of the bias voltage amplifier between different operational states (amplification, standby, or direct connection modes) synchronized with the plasma discharge cycle. This periodic operation allows the system to achieve desired waveform flexibility only when needed while improving overall efficiency by avoiding continuous amplification.
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 solution provides a more stable voltage signal with reduced oscillations, improved process control, and a reduced footprint, enabling closer approach to the ideal voltage waveform, thus enhancing the efficiency and reproducibility of plasma assisted processing.
Implementation Method 1
a first switch node connected to the common node through a first (physical) inductor
Implementation Method 2
The inherent plasma reactor capacitance and the stray inductance of the interconnection between reactor and bias voltage generator form an LC circuit having an inherent resonance characteristic
Data Source
AI summary
A voltage waveform generator includes a common node, a voltage waveform generation circuit and a current source. The voltage waveform generation circuit is operably connected to the common node and is configured to apply a voltage signal at the common node. The current source is operably connected to the common node and configured to apply a DC current at the common node. The current source has a first switch node connected to the common node through a first inductor, and a first power supply connected to the first switch node. The power supply includes at least two first voltage nodes, and the current source is operable to switch between the at least two first voltage nodes at the first switch node.