Processing Gas Flow Control to Prevent Adiabatic Phase Change
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Solution Overview
Problem
In semiconductor manufacturing, the use of mass flow controllers (MFCs) to supply processing gases can lead to adiabatic expansion, causing the gases to re-solidify or re-liquefy and form particles when they reach the reaction tube.
Innovation Solution
A fluid supply system that includes a flow rate controller, an adjuster to supply an adjustment gas downstream of the flow rate controller, and a controller to suppress phase changes by adjusting the adjustment gas based on pressure differences across the flow rate controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mass flow controller is used to control the flow rate of processing gas, then the flow rate control is improved, but adiabatic expansion occurs causing temperature drop and phase change of the gas
Solution Approach 1:
The patent introduces a heating section that pre-heats the processing gas before it enters the mass flow controller. This preliminary heating action prevents the gas from undergoing severe adiabatic expansion and phase change downstream, thereby resolving the temperature drop issue while maintaining flow rate control capability
Solution Approach 2:
The patent introduces a carrier gas as an intermediary substance that mixes with the processing gas. The carrier gas serves as a thermal buffer that mitigates the adiabatic expansion effect and prevents phase change of the processing gas, allowing flow rate control to be maintained without temperature-related problems
2Measurement precision
If processing gas is supplied through a mass flow controller, then precise flow rate control is achieved, but particles are generated due to re-solidification or re-liquefaction of the gas
Solution Approach 1:
The heating section performs preliminary heating of the processing gas before it reaches the mass flow controller, preventing the gas from cooling down and causing re-solidification or re-liquefaction downstream. This eliminates particle generation while preserving precise flow rate control
Solution Approach 2:
The carrier gas acts as an intermediary that prevents direct contact between the processing gas and the cold environment downstream of the mass flow controller. This intermediary layer prevents phase change and particle formation while allowing accurate flow measurement and control to be maintained
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 system effectively suppresses phase changes of the processing gas, preventing particle generation and ensuring stable gas distribution within the substrate processing apparatus, thereby improving film uniformity and process reproducibility.
Implementation Method 1
adiabatic expansion occurs at a subsequent stage of the MFC
Data Source
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AI summary
There is provided a technique that includes: a flow rate controller (100) configured to control a flow rate of fluid flowing in a pipe; an adjuster (72, 54, 76, 95) configured to supply an adjustment gas to at least a downstream side of the flow rate controller (100); and a controller (41) configured to be capable of suppressing a phase change of the fluid, which is caused by a temperature drop due to adiabatic expansion, by supplying the adjustment gas from the adjuster (72, 54, 76, 95) according to a difference between an internal pressure of the flow rate controller (100) and a pressure on a downstream side of the flow rate controller (100).