Angled Gas Inlets for Axisymmetric Plasma in MPCVD
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Solution Overview
Problem
Conventional MPCVD systems experience irregular diamond film deposition due to non-axisymmetric plasma configurations at high pressure, microwave density, and gas flow conditions, leading to uneven material deposition and inhibition of thick film formation.
Innovation Solution
The system employs angled gas inlet structures to manipulate the plasma, either by rotating it relative to the symmetry axis or confining it over the substrate, ensuring axisymmetric film formation through plasma-shaping gas flows, which can be achieved by using a combination of angled and radial gas inlets to control the plasma's shape and position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high pressure and high power density are used in MPCVD, then growth rate is improved, but deposition uniformity deteriorates
Solution Approach 1:
The patent introduces asymmetric angled gas inlets (at angles of 15-45 degrees relative to the substrate normal) to create a controlled asymmetric plasma configuration. This asymmetric gas flow pattern rotates the plasma relative to the substrate, transforming the naturally occurring asymmetric plasma (which causes uneven deposition) into a controlled rotating asymmetric plasma that achieves uniform axisymmetric deposition across the substrate surface.
Solution Approach 2:
The patent employs dynamic gas flow control through multiple gas inlet structures with adjustable flow rates. The angled gas inlets create a dynamic rotating plasma configuration that continuously changes the plasma position relative to the substrate, transforming the static asymmetric plasma into a dynamic system that achieves time-averaged uniform deposition.
2Device complexity
If conventional gas inlet structures are used, then system simplicity is maintained, but plasma symmetry deteriorates
Solution Approach 1:
The gas delivery system is segmented into multiple independent gas inlet structures: a central axisymmetric inlet and multiple angled inlets positioned at different locations. Each inlet can be controlled independently to achieve the desired plasma configuration. This segmentation allows precise control over plasma symmetry while maintaining relatively simple individual inlet components.
Solution Approach 2:
The angled gas inlets act as intermediary elements that mediate between the simple axisymmetric chamber geometry and the desired symmetric plasma configuration. By introducing controlled asymmetric gas flows from these intermediary inlet structures, the system achieves plasma symmetry without requiring complex chamber modifications.
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 enhances the quality and throughput of diamond film deposition by eliminating irregularities, allowing for consistent and efficient growth of thicker diamond films, even beyond the bar formation equilibria point, by maintaining an axisymmetric plasma configuration.
Implementation Method 1
a microwave generator that supplies microwave radiation to the chamber
Implementation Method 2
the microwave radiation provides energy to produce plasma from source gas supplied to the chamber
Implementation Method 3
a first gas inlet structure on the chamber configured to introduce a plasma-shaping gas flow
Implementation Method 4
Chemical precursors in the source gas subsequently react in the plasma through complex gas phase chemistry and fluid dynamics to provide a flux of reactant species that react to grow a desired material on the surface of a substrate
Data Source
AI summary
A film deposition system includes a chamber, a stage disposed in the chamber configured to support a substrate, one or more gas inlet structures configured to supply one or more gases to an interior of the chamber, and one or more microwave-introducing windows that introduce microwave radiation to the chamber to excite the one or more source gases to produce a plasma proximate the stage. The gas inlet structures include one or more angled gas inlets that introduce a plasma-shaping gas flow to the chamber at an angle relative to a symmetry axis of the stage. The plasma-shaping gas flow interacts with the plasma in a way that facilitates axisymmetric deposition of material on a surface of the substrate with the plasma.