Tapered Cross-Flow Reactor for Uniform Gas Deposition
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Solution Overview
Problem
Cross-flow reactors exhibit significant pressure drops and non-uniform gas flow, leading to non-uniform deposition and reaction rates across substrate surfaces due to their small reaction chambers and incomplete seals between the reaction chamber and load/unload areas, resulting in issues like backside and edge deposition.
Innovation Solution
The design incorporates a tapered cross-flow reaction chamber with a varying height from inlet to outlet and includes a spacer between the susceptor and base plate to maintain consistent spacing and allow gas flow, reducing pressure differences and enhancing uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a small reaction chamber is used to enable rapid purging and increase precursor reaction probability, then productivity and reaction efficiency are improved, but pressure drop increases causing non-uniform adsorption/reaction rates across the substrate surface
Solution Approach 1:
The reaction chamber height varies locally along the flow direction, being lower at the inlet and higher at the outlet. This creates different local conditions: the lower inlet region reduces pressure drop to improve uniformity, while the overall compact chamber maintains fast purging capability. Each section of the chamber has optimized height for its specific function.
Solution Approach 2:
The chamber height parameter is changed along the flow direction rather than being uniform. This gradient in height parameter allows the system to balance between maintaining fast purge speeds (small overall volume) and reducing pressure drop (higher outlet region), thereby resolving the contradiction between productivity and deposition uniformity.
2Manufacturing precision
If the reaction chamber has a low vertical height to reduce pressure drop, then deposition uniformity improves, but the reaction chamber volume increases reducing purge speed
Solution Approach 1:
Different sections of the reaction chamber have different heights optimized for their specific locations. The inlet region has lower height to minimize pressure drop and improve uniformity, while the outlet region has higher height to maintain adequate volume for fast purging. This local optimization resolves the contradiction between uniformity and purge speed.
Solution Approach 2:
Instead of uniformly increasing chamber volume in all dimensions to improve uniformity, the design varies the vertical dimension (height) specifically along the flow direction. This targeted dimensional change achieves the uniformity improvement without proportionally increasing overall volume, thus maintaining fast purge capability.
3Ease of operation
If a complete seal is formed between the reaction chamber and load/unload area, then gas flow control improves, but pressure difference non-uniformity across the substrate perimeter increases causing edge and backside deposition
Solution Approach 1:
The sealing structure is extracted or removed from the interface between the reaction chamber and load/unload area. Instead of forming a complete seal, the design allows controlled gas communication between these areas, which equalizes pressure across the substrate perimeter and eliminates edge and backside deposition while maintaining adequate gas flow control through other means.
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 solution significantly reduces pressure drops and achieves more uniform processing by maintaining consistent spacing and allowing controlled gas flow, improving the uniformity of gas-phase processes such as ALD deposition.
Implementation Method 1
cross-flow reactors tend to exhibit a pressure drop from the gas inlet side of the reaction chamber to the flow outlet side of the reaction chamber
Implementation Method 2
gasses generally enter a reaction chamber at one end of the reaction chamber, flow laterally across a substrate within the reaction chamber, and exit at a second end of the reaction chamber
Implementation Method 3
Absorption of a precursor and/or reaction of a reactant on a substrate surface is generally proportional to a pressure within the reaction chamber
Data Source
AI summary
Gas-phase reactors and systems are disclosed. Exemplary reactors include a reaction chamber having a tapered height. Tapering the height of the reactor is thought to reduce a pressure drop along the flow of gasses through the reactor. Exemplary reactors can also include a spacer within a gap to control a flow of gas between a region and a reaction chamber.