Exhaust Gas Cooling by Phase Change After Abatement
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Solution Overview
Problem
Existing methods for treating exhaust gases from processing chambers, such as those used in semiconductor wafer and solar cell manufacturing, face challenges in cooling and handling hot gases efficiently, leading to high water consumption, reliability issues, and increased costs due to the need for larger vacuum pumping and filtration systems, especially when dealing with flammable and toxic substances like hydrogen and silane.
Innovation Solution
The method involves injecting a cooling agent, such as water, downstream of the abatement region to cool the gases through phase change, which absorbs heat without significantly increasing the volume of the gas stream, thereby reducing the load on downstream apparatus and avoiding the need for larger pumping and filtration systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling methods (water column or air-stream) are used to cool exhaust gases, then the gases are cooled, but water consumption increases significantly and gas volume increases requiring larger pumping systems
Solution Approach 1:
The patent applies phase transition by injecting a cooling agent that undergoes phase change from liquid to vapor, absorbing heat from the exhaust gases during evaporation. This evaporative cooling mechanism efficiently reduces gas temperature without requiring large quantities of cooling water, as the phase change process absorbs significant latent heat.
2Temperature
If conventional cooling methods are used, then exhaust gases are cooled, but the volume of gas stream increases requiring larger vacuum pumping and filtration systems
Solution Approach 1:
The cooling agent undergoes phase transition from liquid to vapor, and this vapor mixes with the exhaust gas stream. The phase change process controls the final gas volume by adjusting the amount of cooling agent injected, ensuring efficient cooling while minimizing unnecessary volume increase that would require larger pumping systems.
3Temperature
If larger vacuum pumping and filtration systems are used to handle increased gas volume, then the system can process the cooled gases, but device complexity and cost increase
Solution Approach 1:
By utilizing phase transition of the cooling agent, the system achieves efficient cooling with controlled gas volume increase. This allows the existing vacuum pumping and filtration systems to handle the cooled gases without requiring upgrades to larger, more complex equipment, thereby reducing capital investment and operational complexity.
4Temperature
If water column cooling is used, then exhaust gases are cooled and particulates are entrained, but management and disposal of wet powder becomes problematic and system reliability decreases
Solution Approach 1:
The patent uses phase transition of a cooling agent (which can be water or other suitable fluids) to cool the exhaust gases. The cooling agent evaporates and mixes with the gas stream, avoiding the creation of wet powder that would require complex disposal systems. This approach maintains system reliability by eliminating the reliability issues associated with wet powder management and disposal.
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 effectively cools exhaust gases to below the flammability limit, reduces the risk of ignition, and minimizes the size and energy consumption of vacuum pumping and filtration systems, while also improving the efficiency of wet scrubbing by preconditioning the gas stream.
Implementation Method 1
injecting a cooling agent downstream of the abatement region to cool the abated gases in a cooling region by phase change of the cooling agent
Implementation Method 2
cool the abated gases in a cooling region by phase change of the cooling agent
Implementation Method 3
cool the abated gases in a cooling region by phase change of the cooling agent
Data Source
AI summary
The present invention provides a method of treating an exhaust gas stream 12 from a processing chamber 10. The method comprises the steps of: conveying the exhaust gas from the processing chamber using a vacuum pumping arrangement 11, 22 or atmospheric line; abating the exhaust gas in an abatement region 18 of an abatement device 14; and injecting a cooling agent, such as a liquid 26, downstream of the abatement region to cool the abated gases in a cooling region 24 by phase change of the cooling agent.