Nanosecond Pulse Burst Waveform Generator for High-Capacitance Loads
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Solution Overview
Problem
Producing high voltage pulses with fast rise and fall times, especially in circuits with high capacitance loads, is challenging, particularly when variable pulse widths, voltages, and repetition rates are required.
Innovation Solution
A high voltage waveform generator system comprising a generator inductor, a high voltage nanosecond pulser, and a plasma load, where the generator inductor is charged with pulse bursts, and the plasma voltage varies proportionally with the pulse width and frequency, enabling rapid output pulses with controlled amplitude and duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If standard electrical components are used to generate high voltage pulses, then the circuit design is simple, but the rise time and fall time cannot achieve the required steepness (less than 50 ns)
Solution Approach 1:
The system divides the pulse generation into two stages: a nanosecond pulser that generates short high-voltage pulses, and a generator inductor that integrates these pulses over time to produce the final output pulse. This segmentation allows each component to operate in its optimal performance range, achieving steep rise times without requiring complex single-stage circuitry
Solution Approach 2:
The nanosecond pulser performs preliminary action by generating a burst of high-frequency pulses that charge the generator inductor before the final output pulse is formed. This preliminary charging action enables the system to achieve the required voltage levels and rise times through cumulative effect rather than direct generation
2Speed
If high voltage pulses with fast rise times are generated, then the pulse quality is improved, but the ability to drive high capacitance loads deteriorates
Solution Approach 1:
The system dynamically adjusts the pulse parameters by varying the burst period and pulse width of the nanosecond pulser output. The generator inductor dynamically responds to the input pulse burst by building up voltage over the burst duration, enabling the system to deliver high power to capacitive loads while maintaining fast rise times through controlled energy transfer
3Adaptability or versatility
If variable pulse widths and voltages are required, then the system versatility is improved, but the device complexity increases
Solution Approach 1:
The nanosecond pulser serves multiple functions: it generates the high-frequency pulse burst, controls the output pulse width through burst period modulation, and adjusts output voltage through pulse width modulation. The generator inductor universally handles different input conditions to produce variable output pulses, eliminating the need for separate control circuits for each parameter
4Manufacturing precision
If steep pulse slopes are generated, then the pulse performance is improved, but the difficulty of production increases
Solution Approach 1:
The generator inductor automatically generates the steep pulse slopes through its natural electromagnetic response to the input pulse burst. The inductor's voltage is proportional to the rate of change of current (V = L·di/dt), so the rapid current changes during the burst naturally produce the required steep slopes without additional active control or complex circuitry
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
The system generates high voltage pulses with steep rise and fall times, achieving peak powers up to 10 kW and precise control over pulse widths and voltages, suitable for applications like plasma etching in semiconductor fabrication.
Implementation Method 1
a generator inductor; a high voltage nanosecond pulser electrically and/or inductively coupled with the generator inductor
Implementation Method 2
the voltage across the plasma varying according to: a first plasma pulse having a first output pulse width and a first output voltage
Data Source
AI summary
Some embodiments include a high voltage waveform generator comprising: a generator inductor; a high voltage nanosecond pulser having one or more solid state switches electrically and/or inductively coupled with the generator inductor, the high voltage nanosecond pulser configured to produce a pulse burst having a burst period, the pulse burst comprising a plurality of pulses having different pulse widths; and a load electrically and/or inductively coupled with the high voltage nanosecond pulser, the generator inductor, and the generator capacitor, the voltage across the load having an output pulse with a pulse width substantially equal to the burst period and the voltage across the load varying in a manner that is substantially proportional with the pulse widths of the plurality of pulses.