Heated Mesh Reactor Trap for ALD Effluent
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Solution Overview
Problem
In atomic layer deposition (ALD) processes, large amounts of unreacted reactant gases in effluents cause severe wear and damage to vacuum pumps due to their reaction at high temperatures, leading to frequent pump replacement.
Innovation Solution
A hot reactor trap apparatus with a secondary reaction chamber and a mesh reactor element heated to a temperature that reacts and consumes the unreacted reactant gases before they reach the vacuum pump, utilizing a tortuous flow path to ensure thorough mixing and contact with hot microsurfaces for complete reaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ALD process uses large amounts of reactant gases for deposition, then film deposition quality is improved, but vacuum pump damage increases due to reactant reactions at high temperatures
Solution Approach 1:
The patent extracts and removes unreacted reactant gases from the effluent stream before they reach the vacuum pump. A separate reaction chamber is introduced that specifically targets and removes the harmful reactants (such as trimethylaluminum and oxidant) from the gas flow, separating the deposition function from the pump protection function.
Solution Approach 2:
The patent introduces an intermediary reaction chamber positioned between the ALD reaction chamber and the vacuum pump. This intermediary component provides a controlled environment where unreacted reactants can safely react and be consumed before entering the pump, acting as a buffer that protects the pump from direct exposure to harmful chemicals.
2Device complexity
If reactant gases flow directly to vacuum pump, then system complexity is reduced, but pump wear increases due to formation of abrasive particles
Solution Approach 1:
The patent converts the harmful unreacted reactants into beneficial byproducts by providing a controlled reaction environment. The reactants that would otherwise damage the pump are instead directed into a reaction chamber where they complete their chemical reaction, transforming harmful chemicals into harmless or less harmful substances that can be safely pumped.
3Device complexity
If reactants are not removed from effluent, then equipment simplicity is maintained, but operational costs increase due to frequent pump replacement
Solution Approach 1:
The patent performs preliminary action by removing reactants from the effluent before they reach the vacuum pump. This preventive measure eliminates the root cause of pump degradation, avoiding the need for frequent maintenance and replacement. The reaction chamber continuously processes the effluent stream, ensuring pump protection is maintained throughout operation.
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
Effectively prevents damage to vacuum pumps by reacting and removing virtually all residual reactant gases from the effluent, significantly extending the operational life of the pumps.
Implementation Method 1
heating a reaction element that comprises a mesh in an evacuated secondary reaction chamber positioned in a foreline between the primary or main CVD reaction chamber and the vacuum pump to a temperature that accommodates reaction of the CVD reactants, and flowing the effluent through the mesh in the heated reaction element to react the CVD reactants on the mesh and thereby to consume the reactants
Implementation Method 2
heating a reaction element that comprises a mesh in an evacuated secondary reaction chamber to a temperature that accommodates reaction of the CVD reactants
Data Source
AI summary
A secondary reaction chamber with a mesh reactor element and a heater assembly are positioned in a foreline between a CVD reaction chamber and a vacuum pump to mix and react all previously unreacted precursor reactants to remove them from the effluent before they can reach and damage the vacuum pump.