DC Sputtering with Polarity Reversal for Uniform Film Deposition
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Solution Overview
Problem
Current plasma-based sputtering deposition methods using high-frequency voltage sources are expensive, complex, and fail to achieve uniformity and desired particle generation thresholds, particularly when dealing with insulating deposition materials that coat the anode, preventing electron collection and complicating the sputtering process.
Innovation Solution
A system utilizing direct current power sources with periodically reversed polarity and power modulation, controlled by a feedback loop, to deposit material on a stationary substrate, allowing for flexible electrode placement and precise control of power delivery to achieve desired film characteristics without anode coating issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-frequency voltage sources are used to generate plasma, then plasma can be produced, but the equipment becomes expensive and complex to construct and maintain
Solution Approach 1:
The patent changes the electrical parameter from high-frequency AC voltage to direct current voltage, fundamentally altering how plasma is generated. This parameter change simplifies the power supply equipment while maintaining plasma generation capability, directly resolving the contradiction between reliability and device complexity
Solution Approach 2:
The patent employs periodic reversal of electrode polarity to achieve continuous plasma generation and prevent insulator buildup. This periodic action allows the use of simpler DC power sources while maintaining the plasma generation reliability previously requiring complex high-frequency equipment
2Reliability
If high-frequency voltage sources are used, then plasma can be generated, but the operational complexity increases
Solution Approach 1:
By changing from high-frequency AC to DC voltage operation, the system becomes easier to operate while maintaining plasma generation. DC power supplies are inherently simpler to control and operate, directly addressing the ease of operation concern
3Manufacturing precision
If insulating deposition material is used, then desired film characteristics are achieved, but the anode becomes coated with insulator preventing electron collection
Solution Approach 1:
The periodic reversal of electrode polarity causes the anode to alternately become the cathode, allowing it to be cleaned of insulating deposits during cathode phases. This periodic action maintains anode functionality while allowing insulating materials to be deposited during other phases, resolving the contradiction between film quality and anode performance
Solution Approach 2:
The patent inverts the traditional roles by making both electrodes capable of being cathodes through polarity reversal. This inversion ensures that whichever electrode is anode at any given time will be cleaned when it becomes cathode, preventing the permanent insulator coating problem that would occur with fixed electrode roles
4Reliability
If standard pulsed direct current power sources are used, then anode coating issues are resolved, but uniformity and particle generation thresholds are not achieved
Solution Approach 1:
The patent implements feedback control that monitors deposition characteristics and adjusts power delivery parameters in real-time. This feedback mechanism enables precise control over film uniformity and particle generation while maintaining the benefits of pulsed DC operation, resolving the contradiction between anode reliability and film quality
Solution Approach 2:
The system dynamically adjusts power delivery parameters including pulse duration, amplitude, and timing based on real-time process conditions. This dynamic control allows optimization of both anode operation and film deposition quality, achieving what standard fixed-parameter pulsed DC sources cannot accomplish
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 enables uniform and controlled deposition of materials with desired characteristics, reduces contamination, and extends the time between maintenance cycles by maximizing target material usage while minimizing unwanted material removal, improving the quality and efficiency of the sputtering process.
Implementation Method 1
a power supply creates an electric potential between a cathode and one or more anodes that are placed in a plasma chamber containing the process gases that form the plasma
Implementation Method 2
a power supply creates an electric potential between a cathode and one or more anodes
Implementation Method 3
Plasma ions are accelerated towards the target and cause target material to be dislodged from the cathode surface on impact
Implementation Method 4
Plasma ions are accelerated towards the target and cause target material to be dislodged from the cathode surface on impact
Implementation Method 5
The dislodged target material is then deposited on a substrate to form a film... material sputtered by the plasma from the target surface
Implementation Method 6
The dislodged target material is then deposited on a substrate to form a film
Data Source
AI summary
An apparatus and methods for plasma-based sputtering deposition using a direct current power supply is disclosed. In one embodiment, a plasma is generated by connecting a plurality of electrodes to a supply of current, and a polarity of voltage applied to each of a plurality of electrodes in the processing chamber is periodically reversed so that at least one of the electrodes sputters material on to the substrate. And an amount of power that is applied to at least one of the plurality of electrodes is modulated so as to deposit the material on the stationary substrate with a desired characteristic. In some embodiments, the substrate is statically disposed in the chamber during processing. And many embodiments utilize feedback indicative of the state of the deposition to modulate the amount of power applied to one or more electrodes.