Master-Slave MFC Network for Chamber Pressure and Flow Ratio Control
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Solution Overview
Problem
In semiconductor fabrication, maintaining precise control over the pressure in a processing chamber and the flow ratios of multiple fluids delivered to it is challenging, as existing systems struggle to efficiently manage these variables simultaneously.
Innovation Solution
A digital communication network-linked mass flow controller system, featuring a master and slave configuration, where the master MFC receives set points and commands from a host controller to maintain chamber pressure and flow ratios, ensuring accurate control of fluid flow rates and pressure within the processing chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple mass flow controllers are used to control individual flow rates of each fluid, then the flow ratios can be maintained at desired set point values, but the system complexity and cost increase significantly
Solution Approach 1:
The system divides the control function into a master MFC that handles pressure control and flow ratio calculations, and slave MFCs that execute simplified control commands. This segmentation allows precise flow ratio control while reducing the computational burden and complexity on individual controllers.
Solution Approach 2:
The master MFC serves multiple functions: it acts as a pressure controller, a flow ratio calculator, and a command distributor to slave MFCs. This multi-functionality reduces the need for separate dedicated controllers for each function, thereby reducing overall system complexity while maintaining precision.
2Manufacturing precision
If multiple mass flow controllers are used to control individual flow rates, then flow ratio control is achieved, but the cost of the system increases
Solution Approach 1:
The system merges the pressure control function and flow ratio control function into a single master MFC. This consolidation reduces the total number of controllers needed, lowering system cost while maintaining the precision of flow ratio control through centralized calculation and coordination.
Solution Approach 2:
The master MFC is designed to perform multiple functions including pressure regulation, flow ratio calculation, and coordination of slave MFCs. This multi-functionality eliminates the need for separate expensive dedicated controllers, reducing overall system cost while preserving control precision.
3Reliability
If chamber pressure is controlled while maintaining flow ratios of multiple fluids, then processing conditions are optimized, but the control difficulty increases
Solution Approach 1:
The master MFC receives real-time pressure feedback from the chamber and flow rate feedback from slave MFCs. It continuously calculates the total flow rate and adjusts individual flow ratios accordingly to maintain both pressure stability and desired flow ratios, reducing control difficulty through automated feedback loops.
Solution Approach 2:
The master MFC acts as an intermediary between the pressure control system and the individual fluid flow control systems. It coordinates the actions of multiple slave MFCs to achieve the desired flow ratios while maintaining chamber pressure, simplifying the overall control operation through centralized mediation.
Data Source
AI summary
An integrated pressure and flow ratio control system includes N mass flow controllers MFCi (i=1, . . . , N) that each control the flow rate of a fluid Fi (i=1, . . . , N) flowing into a processing chamber. These N mass flow controllers are linked together by a digital communication network. One of the mass flow controllers is a master MFC, and the remaining N−1 MFCs are slave MFCs. The master MFC receives a pressure set point and a plurality N of flow ratio set points from a host controller, and communicates these set points to all the slave MFCs. In this way, the pressure in the chamber is maintained at the pressure set point and the flow ratios Qi/QT are maintained at the flow ratio set points, where Qi is flow rate of the i-th fluid Fi, and QT=Q1+Q2+ . . . QN is the sum of all N flow rates.