Broad Beam Plasma Source With Convex Flux for Low-Damage Thin Films
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Solution Overview
Problem
Conventional ion sources emit narrow ion beams, require high voltages that can damage films, and lack independent control over ion energy and flux, making them unsuitable for large-area applications and reactive gas environments.
Innovation Solution
A broad beam plasma source with a convex magnetic flux and combined DC/RF power supply, enabling independent control of ion energy and flux, and operation in a wide range of pressures and gases, including reactive gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ion sources use high voltage (>300 V) to sustain plasma, then plasma is sustained, but ion energy becomes too high which damages deposited films and roughens film surfaces
Solution Approach 1:
The patent changes the voltage parameter from high voltage (>300V) to low voltage (5-250V) operation by implementing a specific electrode geometry with a large area anode positioned close to a small area cathode. This geometric configuration enables plasma sustainment at lower voltages, preventing film damage while maintaining plasma discharge.
2Reliability
If conventional ion sources use narrow gap between anode and cathode to create strong fields, then plasma is sustained, but ion beam becomes narrow which is unsuitable for large-area applications
Solution Approach 1:
The patent applies local quality by creating a non-uniform electric field distribution where the strong field region is concentrated in the narrow gap between the small area cathode and the large area anode. This localized field concentration sustains plasma effectively while the large anode area enables broad ion beam emission suitable for large-area substrates.
Solution Approach 2:
The patent transitions from a symmetric electrode configuration to an asymmetric one where the anode area is significantly larger than the cathode area. This dimensional asymmetry allows the plasma sustainment region to be localized near the cathode while the ion beam emission area is determined by the large anode, decoupling these two requirements.
3Reliability
If conventional ion sources use high voltage to sustain plasma, then plasma is sustained, but ion flux becomes low which is insufficient for high productivity applications
Solution Approach 1:
The patent changes the operating voltage parameter to low voltage (5-250V) and compensates for the reduced ion energy by increasing the ion flux through the large area anode configuration. The total ion current is enhanced by the increased emission area, maintaining productivity while operating at lower voltages that prevent film damage.
4Ease of operation
If conventional ion sources emit narrow ion beams, then ion energy control is simplified, but uniform treatment of workpiece surface cannot be achieved
Solution Approach 1:
The patent creates local quality in the electric field distribution with the narrow gap concentrated at specific regions between the small cathode and large anode. This localized field structure enables controlled ion acceleration while the large anode area ensures broad, uniform ion beam coverage across the entire workpiece surface.
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
Enables uniform thin-film deposition and improved film quality over large areas with adjustable ion-surface interactions, enhancing deposition rates and film properties.
Implementation Method 1
a first power supply coupled to the ion source and configured to provide a combined direct current (DC) and radio frequency (RF) power to excite the ion source
Implementation Method 2
Ion sources are plasma generation devices that emit ion beams to interact with the atoms as they are deposited
Implementation Method 3
Anode layer ion sources require a narrow gap of a few millimeters between the anode and cathode to create strong electric and magnetic fields to sustain a plasma
Implementation Method 4
a set of magnets and shunts that create convex magnetic flux lines across and above the surface of the anode pole
Data Source
AI summary
A broad beam plasma or ion source is provided, which includes an anode pole extending beyond the top surface of the cathode. A further aspect of a broad ion source includes magnets and magnetic shunts which create convex magnetic flux across and above the anode pole, which intercepts a significant portion of the magnetic flux. In another aspect, a broad beam ion source includes a magnetic surrounding cathode that prevents the magnetic flux from leaking out of the ion source. A further aspect provides a broad beam plasma source which is excited by combined DC and RF powers to create ions and reactive species to interact with specimen. Yet in a further aspect, a broad beam ion source operates simultaneously with another deposition source at the same internal pressure in a vacuum chamber for making high-quality thin films.