Overlapping Power Impulses for PVD Sputtering Cathodes

Solution Overview

Problem

Existing power impulse generators in HIPIMS technology face challenges in delivering short, high-power impulses with defined profiles, leading to suboptimal layer properties due to dynamic and uncontrolled output profiles, and significant power losses when switching between partial cathodes.

Innovation Solution

The method involves overlapping power impulse intervals between partial cathodes to maintain continuous power draw without interruptions, using a dummy cathode to ensure full power availability during transitions, and optimizing power impulse cycles to minimize power loss, especially for short impulse durations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If power impulses are shortened to prevent cathode overheating, then cathode temperature control is improved, but the generator cannot deliver full power within the shortened time window

Engineering Contradiction:

Improvecathode temperatureVSAvoidgenerator output power

Core Design Contradiction:

TemperatureVSPower

Solution Approach 1:

The cathode is divided into multiple partial cathodes (first partial cathode, second partial cathode, etc.) that can be operated sequentially. This segmentation allows the system to maintain high power delivery by switching between multiple cathode segments, preventing any single cathode from overheating while ensuring the generator always has a ready cathode to deliver full power.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The method employs overlapping power impulse intervals where the second partial cathode is prepared in advance while the first partial cathode is still receiving power. This preliminary preparation ensures that when the first cathode needs to be switched off for cooling, the second cathode is already ready to immediately take over power delivery, eliminating power delivery interruptions.

Inventive Principle:

Principle #10Preliminary action

2Temperature

If power is switched between partial cathodes to enable cooling, then cathode temperature control is improved, but power delivery interruptions occur during switching

Engineering Contradiction:

Improvecathode temperatureVSAvoidpower delivery continuity

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The method employs overlapping power impulse intervals where the second partial cathode is prepared in advance while the first partial cathode is still receiving power. This preliminary preparation ensures that when the first cathode needs to be switched off for cooling, the second cathode is already ready to immediately take over power delivery, eliminating power delivery interruptions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The power impulse intervals of different partial cathodes are designed to overlap in time, ensuring continuous power delivery from the generator. The transition from one partial cathode to another occurs without interruption, maintaining the continuity of the sputtering process and eliminating harmful pauses in power delivery.

Inventive Principle:

Principle #20Continuity of useful action

3Temperature

If sequential power delivery to partial cathodes is implemented, then cathode cooling is improved, but power loss increases during transitions

Engineering Contradiction:

Improvecathode temperatureVSAvoidpower loss during switching

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The method employs overlapping power impulse intervals where the second partial cathode is prepared in advance while the first partial cathode is still receiving power. This preliminary preparation ensures that when the first cathode needs to be switched off for cooling, the second cathode is already ready to immediately take over power delivery, eliminating power delivery interruptions.

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

This approach allows for scalable impulse duration and frequency with minimal power loss, resulting in improved layer properties and reproducibility by maintaining continuous power delivery and reducing overheating risks in the cathodes.

Implementation Method 1

During the overlap time of the two power impulse intervals, the plasma burns only on the first partial cathode since the respective impedance is considerably lower relative to the impedance of the not yet ignited second partial cathode

Methodology Applied

Scientific EffectElectrical Impedance: Electrical Resistance

Implementation Method 2

It is only when at the end of the first power impulse interval the first partial cathode is separated from the generator that the plasma ignites on the second partial cathode

Methodology Applied

Scientific EffectPlasma ignition: Electric Arc

Implementation Method 3

When switching on the power supply that is supposed to deliver an output of e.g. 40 kW, a timespan on the order of approx. 700 μs will elapse until complete power delivery

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS9267200B2Method for supplying sequential power impulses

Publication Date: 2016.02.23 OERLIKON SURFACE SOLUTIONS AG PFAFFIKON

AI summary

The invention relates to a method for supplying power impulses for PVD sputtering cathodes subdivided into partial cathodes. In said method, the power impulse intervals acting on the partial cathodes are selected in such a way as to overlap, thereby dispensing with the need to interrupt the drawing of power supplied by the generator.