Non-Dissipative Snubber Circuit for Plasma Processing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing power supply systems for plasma processing face challenges such as voltage and current spikes, inefficiencies due to power dissipation, and unwanted arcing caused by charge buildup on sputtering cathodes, leading to reduced throughput and increased losses.

Innovation Solution

A non-dissipative snubber circuit is introduced, comprising a unidirectional switch, voltage multiplier, and current limiter, which absorbs power during impedance increases and discharges it non-dissipatively when impedance decreases, while also boosting voltage and current ramp rates to improve efficiency and reduce arcing by periodically reversing the voltage applied between the cathode and anode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a dielectric layer forms on the sputtering cathode, then charge buildup occurs on the outside of the dielectric, but this leads to unwanted arcing and reduced system reliability

Engineering Contradiction:

Improvesystem reliabilityVSAvoidunwanted arcing

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies periodic bipolar voltage pulsing to the sputtering cathode, where the polarity reverses between positive and negative half-cycles. This periodic action removes charge buildup on the dielectric layer surface by repelling accumulated charges during polarity transitions, preventing arcing while maintaining reliable plasma generation during the positive half-cycles

Inventive Principle:

Principle #19Periodic action

2Reliability

If existing dissipative snubbers are used to mitigate voltage and current spikes, then switching circuit damage is reduced, but significant power is dissipated leading to decreased efficiency

Engineering Contradiction:

Improveswitching circuit protectionVSAvoidpower dissipation

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent converts the harmful voltage and current spikes into beneficial energy storage by using a non-dissipative snubber circuit that captures the spike energy and stores it in a capacitor. This stored energy is then returned to the plasma load during the positive half-cycle, protecting the switching circuit from damage while eliminating power dissipation losses

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The non-dissipative snubber circuit recovers energy that would otherwise be wasted during voltage and current spikes. The captured energy is stored and subsequently returned to the plasma load, transforming what would be discarded energy into useful power for the plasma processing

Inventive Principle:

Principle #34Discarding and recovering

3Reliability

If DC pulse frequency is increased to reduce arcing, then plasma stability improves, but current becomes larger leading to increased power losses proportional to I²

Engineering Contradiction:

Improveplasma stabilityVSAvoidpower losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The bipolar pulsed DC power supply delivers power in periodic pulses with controlled duty cycle and frequency. By optimizing the pulse parameters and using periodic polarity reversal, the system maintains plasma stability and prevents charge buildup without requiring continuously high currents, thereby reducing I² power losses while achieving arc-free operation

Inventive Principle:

Principle #19Periodic action

4Speed

If voltage switches with negligible ramp time, then switching speed is improved, but current ramps slowly providing average power significantly lower than power supply output

Engineering Contradiction:

Improvevoltage switching speedVSAvoidaverage power delivery

Core Design Contradiction:

SpeedVSPower

Solution Approach 1:

The non-dissipative snubber circuit performs preliminary action by capturing voltage and current spike energy before it can be wasted. This pre-captured energy is then immediately returned to the plasma load during the positive half-cycle, effectively boosting the average power delivery without sacrificing the fast voltage switching capability of the power supply

Inventive Principle:

Principle #10Preliminary action

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 solution effectively mitigates voltage and current spikes, enhances processing throughput, reduces power losses, and minimizes arcing by efficiently managing power delivery and charge removal in plasma processing systems.

Implementation Method 1

voltage multiplier, which absorbs power during impedance increases and discharges it non-dissipatively when impedance decreases, while also boosting voltage

Methodology Applied

Scientific EffectVoltage multiplication: Capacitance

Implementation Method 2

DC power supply providing DC power to a switching circuit that converts the DC power into pulsed DC and provides the pulsed DC to a plasma load

Methodology Applied

Scientific EffectPlasma generation: Ionisation

Data Source

PatentUS9620340B2Charge removal from electrodes in unipolar sputtering system

Publication Date: 2017.04.11 AES GLOBAL HLDG PTE LTD

AI summary

This disclosure describes a non-dissipative snubber circuit configured to boost a voltage applied to a load after the load's impedance rises rapidly. The voltage boost can thereby cause more rapid current ramping after a decrease in power delivery to the load which results from the load impedance rise. In particular, the snubber can comprise a combination of a unidirectional switch, a voltage multiplier, and a current limiter. In some cases, these components can be a diode, voltage doubler, and an inductor, respectively.