Sputtering Method With Deviated Short-Circuit Timing
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Solution Overview
Problem
Conventional sputtering methods experience significant switching noises during power switching, leading to inaccurate charging of targets and potential disorder in the power waveform, especially with multiple bipolar pulsed power supplies in parallel, which can impair thin film formation.
Innovation Solution
The method involves using an output-short-circuiting switching element with deviated switching timing to reduce the number of operating switching elements and minimize switching noises, allowing for high-accuracy power charging to targets, even with multiple bipolar pulsed power supplies connected in parallel, by employing a bridge circuit with ON/OFF control and bus bars for power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple bipolar pulsed power supplies are disposed in parallel to increase productivity, then the sputtering efficiency is improved, but switching noises increase and power charging accuracy deteriorates
Solution Approach 1:
A reactive element (capacitor or inductor) is introduced as an intermediary component between the bipolar pulsed power supply and the target. This reactive element absorbs and filters the switching noises generated during power supply operation, preventing them from disrupting the power charging process. The reactive element acts as a buffer that isolates the noise source from the sensitive power charging function, thereby maintaining power charging accuracy even when multiple power supplies operate in parallel.
2Area of stationary object
If the number of bipolar pulsed power supplies is increased to process large-area substrates, then the processing area is expanded, but switching noises become more remarkable and waveform stability deteriorates
Solution Approach 1:
The reactive element serves as a noise filtering intermediary for each power supply unit, preventing switching noises from propagating and causing waveform instability. By placing this intermediary component in each parallel power supply branch, the system can expand to cover larger substrate areas without sacrificing waveform stability, as each branch's noise is independently filtered.
3Reliability
If bipolar pulsed power supply is used to cancel electric charges on target surface, then discharge stability is improved, but switching noises are generated during polarity switching
Solution Approach 1:
The reactive element is positioned between the power supply switching mechanism and the target, acting as a mediator that allows the bipolar pulsed operation to continue (maintaining discharge stability) while filtering out the switching noises generated during polarity transitions. The reactive element smooths the current transitions, reducing the amplitude of switching noise without preventing the charge cancellation effect.
4Measurement precision
If switching elements are operated at high frequency to charge power accurately, then power charging speed is improved, but switching losses increase and durability deteriorates
Solution Approach 1:
The reactive element acts as an energy buffer that reduces the stress on switching elements during high-frequency operation. By storing and releasing energy smoothly, the reactive element allows for faster charging cycles without proportionally increasing switching losses, as the reactive element handles some of the energy transition burden, reducing the frequency and intensity of switching operations required.
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 effectively reduces switching noises and improves power accuracy, enhancing the durability and control of the sputtering process while maintaining high precision in thin film formation, even with increased numbers of bipolar pulsed power supplies.
Implementation Method 1
alternately switching each of the targets to anode electrode and cathode electrode to cause glow discharge to take place between the anode electrode and the cathode electrode
Implementation Method 2
Glow discharge is caused to be generated between the anode electrode and the cathode electrode to thereby form a plasma atmosphere
Implementation Method 3
a sputtering method for forming a predetermined thin film on the surface of a substrate to be processed
Data Source
AI summary
When sputtering method is performed by disposing a plurality of targets in parallel with each other, and by charging power to the targets through a plurality of bipolar pulsed power supplies, power can be charged with higher accuracy to the targets while being subject to less effect by the switching noises by a simple control. In a sputtering method in which, for each of targets making a pair, power is supplied in a bipolar pulsed mode by switching ON or OFF of each of the switching elements SW1 through SW4 in a bridge circuit that is connected to positive and negative DC output ends from the DC power supply source, and in which each of the targets is sputtered, switching ON or OFF of the switching elements is performed in a short-circuited state of an output-short-circuiting switching element SW0 which is disposed between positive and negative DC outputs from the DC power supply source. The timing of shifting the output-short-circuiting switching element is mutually deviated from bridge circuit to bridge circuit.