Plasma Bias Waveform Generator Using Multi-Level Resonant Commutation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current plasma processing technologies face inefficiencies in generating bias voltage waveforms, leading to excessive commutation losses and uncontrolled resonance ringing, which affect ion energy distribution and process control in plasma assisted etching and deposition.
Innovation Solution
A voltage waveform generator with a power stage topology that enables resonant commutation, using multiple voltage levels and precise switch control to achieve lossless commutation and prevent resonance ringing, allowing for faster and more precise generation of the desired substrate voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If switch mode power supply is used to generate periodic voltage function, then ion energy intensity distribution can be controlled, but commutation losses increase significantly
Solution Approach 1:
The patent applies periodic action by using a switch mode power supply to generate a periodic voltage function that is applied to the substrate surface. This periodic voltage waveform enables precise control of ion energy intensity distribution during plasma processing, while the periodic nature allows for optimized switching that reduces commutation losses compared to continuous control methods.
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting the voltage function parameters (amplitude, frequency, waveform shape) applied to the substrate. This allows precise control of ion energy distribution by changing the electrical parameters of the periodic voltage, enabling optimization of both processing quality and energy efficiency during plasma etching or deposition processes.
2Stability of the object's composition
If damping resistance or snubber is added to prevent resonance ringing, then voltage waveform stability improves, but additional energy losses occur
Solution Approach 1:
The patent implements feedback control by monitoring the actual voltage waveform applied to the substrate and adjusting the switching signals accordingly. This closed-loop feedback mechanism maintains voltage waveform stability and prevents resonance ringing without requiring additional damping resistance or snubber circuits, thereby avoiding the energy losses that would be introduced by such passive damping elements.
3Productivity
If switching speed is increased to reduce discharge time, then process throughput improves, but resonance excitation and ringing increase
Solution Approach 1:
The patent applies dynamics by using dynamic switching control where the switching speed and timing are continuously adjusted based on real-time process conditions. This dynamic control enables fast switching to improve throughput while simultaneously adapting to prevent resonance excitation, eliminating the need for fixed slow switching speeds that would limit productivity.
Solution Approach 2:
The patent implements self-service through self-bias generation where the plasma process itself generates the bias voltage needed for ion energy control. This self-bias mechanism naturally dampens resonance effects and prevents ringing without requiring external damping components, allowing fast switching speeds that improve throughput while maintaining waveform stability.
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 approach results in higher efficiency, reduced disturbance during discharge, and improved process control with a narrower ion energy distribution, enhancing throughput and reproducibility in plasma processing.
Implementation Method 1
The power stage topology comprises different voltage levels which can consecutively be coupled to the output for obtaining the periodic bias voltage. The number of voltage levels is such that resonant commutation during a change of voltage levels of the waveform can be obtained
Implementation Method 2
a plasma reactor has an inherent reactor capacitance and the interconnection between reactor and bias voltage generator a stray inductance, which form a LC circuit having an inherent resonance characteristic
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Method and device of generating a voltage waveform at an output (14), comprising providing a first DC voltage having a first magnitude (V1), a second DC current (I2) having a second magnitude, a third DC voltage having a third magnitude (V3), and a fourth DC voltage having a fourth magnitude (V4), wherein the first (V1) magnitude is higher than the third (V3) and fourth (V4) magnitude. The fourth DC voltage is coupled to the output (14) followed by coupling the first DC voltage to the output, to bring an output voltage (VP) at the output (14) to a high level. The first DC voltage is decoupled from the output (14), followed by coupling the third DC voltage to the output, to obtain a drop of the output voltage (VP). A ground potential (V0) is coupled to the output (14) following coupling the third DC voltage and the second DC current (I2) is coupled to the output (14) following coupling the ground potential, wherein the second DC current ramps down the output voltage (VP).