MFC Pulse Gas Delivery Using External Pressure Trigger Feedback
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Solution Overview
Problem
Existing pulse gas delivery systems for semiconductor processes waste expensive process gas due to constant flow modes and reliance on downstream valves, leading to inaccurate and repeatable pulse gas delivery, especially in applications like atomic layer deposition where precise mole amounts are required.
Innovation Solution
A fluid control system incorporating a mass flow controller (MFC) with a shutoff valve, where the MFC uses an external pressure trigger and feedback from a flow sensor to initiate and terminate pulses of fluid, minimizing waste by calculating and delivering precise mole amounts directly into the processing chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If constant flow mode is used with downstream valve control, then gas delivery can be implemented, but expensive process gas is wasted and delivery accuracy deteriorates
Solution Approach 1:
The patent inverts the conventional control approach by placing the control valve upstream in the MFC rather than downstream. This reversal allows the MFC to precisely control the pulse gas delivery from the source, preventing gas waste in constant flow mode while maintaining accurate pulse delivery to the processing chamber.
Solution Approach 2:
The patent implements feedback control where the MFC controller receives signals from the shutoff valve and continuously adjusts the control valve to maintain precise pulse delivery. This closed-loop feedback system ensures accurate mole amount delivery while minimizing gas waste by stopping flow when the pulse is complete.
2Device complexity
If downstream shutoff valve is used for pulse control, then pulse delivery can be achieved, but system complexity increases and repeatability worsens
Solution Approach 1:
The patent combines the pulse control function into the MFC itself by integrating an upstream control valve with the mass flow controller. This merging eliminates the need for separate downstream shutoff valve control systems, reducing overall system complexity while improving pulse delivery repeatability through unified control.
Solution Approach 2:
The MFC performs self-control of pulse delivery through its integrated controller and control valve. The system uses feedback from the shutoff valve signal to automatically regulate its own flow, making the pulse control self-contained within the MFC and improving reliability without adding external complexity.
3Manufacturing precision
If upstream control valve is integrated in MFC, then gas waste is minimized and delivery precision improves, but control system complexity increases
Solution Approach 1:
The MFC controller is designed to perform multiple functions: it controls the upstream control valve for precise flow regulation, receives feedback signals from the shutoff valve, and manages pulse timing. This multi-functionality integrates control capabilities within the existing MFC, improving precision without requiring separate dedicated control systems.
Solution Approach 2:
The patent utilizes changes in control parameters (flow rate, pulse timing, valve position) managed by the MFC controller to achieve precise mole amount delivery. By dynamically adjusting these parameters based on feedback, the system achieves high precision while the controller handles the complexity of coordinating multiple parameters.
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 solution enables precise and efficient pulse gas delivery, minimizing gas waste and improving accuracy and repeatability, while being easily retrofittable into existing tools with minimal hardware and software changes, suitable for demanding processes like ALD.
Implementation Method 1
The MFC can include a pressure sensor to sense the pressure signal. The pressure sensor can receive the pressure signal via a tap into a pneumatic line, pressure in the line opening and closing the shutoff valve.
Implementation Method 2
The control valve is preferably a proportional valve that produces a flow output that is proportional to a control input (e.g. an electronic control input from a host controller). The proportional control valve can be used to control the flow of fluid passing through the valve orifice.
Implementation Method 3
a flow sensor to measure flow rate in the flow channel, and a controller having a valve input from the shutoff valve indicating opening of the shutoff valve.
Data Source
AI summary
A fluid control system and associated method for pulse delivery of a fluid includes a shutoff valve and a mass flow controller (MFC) upstream of the shutoff valve. The MFC includes a flow channel, a control valve to control flow of fluid in the flow channel, a flow sensor to measure flow rate in the flow channel, and a controller having a valve input from the shutoff valve indicating opening of the shutoff valve. The controller is configured to respond to the valve input to control flow of fluid through the control valve to initiate and terminate a pulse of fluid from the flow channel to the shutoff valve to control a mass of fluid delivered during the pulse of fluid. The valve input can be a pressure signal, and the MFC can include a pressure sensor to sense the pressure signal.