RPCVD Showerhead Layout for Uniform Plasma and Gas Distribution
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Solution Overview
Problem
Remote Plasma Chemical Vapour Deposition (RPCVD) techniques face challenges in achieving uniform distributions of active nitrogen species due to quenching effects from collisions with apparatus walls, leading to reduced density at the growth surface, which complicates the design of showerheads and plasma distribution systems.
Innovation Solution
The RPCVD apparatus features a showerhead with strategically positioned plasma and gas inlets, where plasma inlets are larger than gas inlets, and gas inlets are distributed in a pattern to ensure uniform gas density across the susceptor surface, utilizing susceptor rotation to maintain uniform distributions despite the presence of larger plasma inlets, and a controller adjusts flux and plasma power for optimal distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single plasma inlet is used to deliver plasma into the reaction chamber, then the apparatus structure is simplified, but the plasma density distribution at the growth surface becomes non-uniform
Solution Approach 1:
The single plasma inlet is divided into multiple plasma inlets (first plasma inlet and second plasma inlet) positioned at different locations. This segmentation allows plasma to be delivered from multiple points, creating overlapping plasma regions that collectively provide uniform plasma density distribution across the growth surface while maintaining relatively simple apparatus structure.
2Quantity of substance
If showerhead components are placed close to the susceptor to improve plasma delivery, then active nitrogen species density increases, but wall collisions and quenching effects increase
Solution Approach 1:
The plasma inlets are positioned to deliver plasma in a direction that creates overlapping plasma regions above the susceptor. By utilizing the spatial dimension and creating volumetric plasma overlap rather than relying solely on proximity to the susceptor surface, the design delivers sufficient active nitrogen species density while maintaining larger distances from walls to reduce quenching collisions.
3Manufacturing precision
If multiple plasma inlets are provided to achieve uniform plasma distribution, then plasma density uniformity improves, but the showerhead structure becomes more complex
Solution Approach 1:
The first and second plasma inlets are positioned asymmetrically at different locations relative to the susceptor. This asymmetric arrangement allows each inlet to target specific regions, and their combined effect achieves uniform plasma distribution. The asymmetric design avoids the need for highly symmetric complex structures while maintaining effectiveness.
4Productivity
If plasma inlets have large openings to deliver sufficient plasma, then plasma delivery efficiency improves, but gas inlet distribution uniformity becomes more difficult to achieve
Solution Approach 1:
Different regions of the showerhead are assigned different functions with locally optimized characteristics. The plasma inlets have larger openings optimized for plasma delivery efficiency to specific regions, while gas inlets are distributed in patterns optimized for uniform gas density. Each location has properties tailored to its specific role, achieving both efficient plasma delivery and uniform gas distribution.
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 configuration achieves substantially uniform distributions of plasma and gas density on the susceptor surface, minimizing wall collisions and maximizing active nitrogen species delivery, thereby improving film deposition quality and process efficiency.
Implementation Method 1
one or more plasma generators to generate a plasma from a gas source comprising nitrogen gas
Implementation Method 2
a reaction chamber in which to react a metal organic reagent with an active nitrogen species derived from the plasma so as to deposit a film on one or more substrates
Implementation Method 3
the susceptor being configured to rotate relative to the showerhead around an axis of rotation
Implementation Method 4
RPCVD delivers the nitrogen species in the form of a plasma, particularly a plasma generated from a gas comprising nitrogen, thus generating a nitrogen plasma. The nitrogen plasma is generated remotely, and the plasma is then delivered into the reactor in the excited state in order to react with the MO to grow the film
Data Source
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AI summary
RPCVD apparatus for forming a film is disclosed including a showerhead having at least one gas chamber, one or more plasma inlets to deliver plasma from one or more plasma generators into a reaction chamber; and a plurality of gas inlets to deliver gas from at least one gas chamber into the reaction chamber. At least one of the plasma inlets is located at a position that is between a central region and an outer region of the showerhead and off-centre from an axis of rotation. The plasma generators generate plasma in line of sight of the susceptor and the plasma inlets have openings that are larger than openings of the gas inlets. The gas inlets are configured such that a combination of all of the spatial distributions of gas from the gas inlets provides a uniform distribution of gas density on the surface of a susceptor between a central region and an outer region of the susceptor, for a full rotation of the susceptor.