Pulsed DC Sputtering with Phase-Synchronized Bipolar Power
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Solution Overview
Problem
Current sputtering systems face challenges in achieving high deposition rates without excessive heat load, particularly when depositing materials like TiO2 or SiO2 on polyethylene substrates, which are sensitive to high temperatures, leading to low-quality layers and increased production time.
Innovation Solution
A pulsed direct current sputtering system with synchronized bi-polar power sources applied to magnetrons and an anode, reducing heat load while maintaining high deposition rates by phase-synchronizing voltages to achieve additive anode current without exceeding substrate tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high power is applied to achieve high deposition rate, then productivity is improved, but temperature increases causing damage to polyethylene substrates
Solution Approach 1:
The patent applies pulsed DC power delivery with alternating polarity to the magnetron, creating periodic on/off cycles of plasma generation. During the off-cycle, the substrate cools down, preventing heat accumulation and damage to temperature-sensitive polyethylene substrates while still achieving high deposition rates during the on-cycles
Solution Approach 2:
The patent changes the electrical parameters by using bi-polar pulsed DC instead of traditional AC or unipolar DC, allowing independent control of pulse width, duty cycle, and peak power. This enables optimization of deposition rate while controlling substrate temperature through parameter adjustment
2Temperature
If power is reduced to protect polyethylene substrates from heat damage, then temperature is controlled, but deposition rate decreases leading to low-quality layers and increased production time
Solution Approach 1:
By using pulsed operation with high peak power during short on-cycles followed by cooling off-cycles, the system achieves high deposition rates during plasma generation while allowing substrate temperature to remain controlled through the periodic interruption of power delivery
Solution Approach 2:
The system dynamically adjusts the duty cycle and pulse width to optimize the balance between deposition rate and substrate temperature, allowing high power input when needed for fast deposition while providing cooling periods to protect the substrate
3Productivity
If traditional AC sputtering is used, then system complexity is low, but deposition rate is insufficient for commercial production requirements
Solution Approach 1:
The patent uses bi-polar pulsed DC power delivery which, while more complex than simple AC, provides independent control of pulse width and duty cycle parameters, enabling optimization of deposition rate for commercial production while maintaining manageable system complexity through standardized power supply design
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 achieves twice the deposition rate of traditional AC systems with half the heat load, enabling high-quality thin film deposition on polyethylene substrates without damage, and allows for faster production without additional cooling.
Implementation Method 1
Sputtering historically includes generating a magnetic field in a vacuum chamber and causing a plasma beam in the chamber to strike a sacrificial target, thereby causing the target to sputter (eject) material, which is then deposited as a thin film layer on a substrate
Implementation Method 2
Sputtering sources may employ magnetrons that utilize strong electric and magnetic fields to confine charged plasma particles close to the surface of the target
Implementation Method 3
A first power source is coupled to a first and second power leads, and the first power source is configured to provide a first voltage that alternates between positive and negative relative to the first power lead during each of multiple cycles
Data Source
AI summary
A sputtering system and method are disclosed. The system includes first power source coupled between a first and second power leads, and the first power source provides a first voltage that alternates between positive and negative during each of multiple cycles. The system also includes a second power source coupled between the second power lead and a third power lead, and the second power source provides a second voltage that alternates between positive and negative during each of the multiple cycles. A controller of the system controls the first power source and the second power source to phase-synchronize the first voltage with the second voltage, so both, the first voltage and the second voltage, are simultaneously negative during a portion of each cycle and simultaneously positive during another portion of each cycle.