Pulse Gas Delivery with Dual Flow and Pressure Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing pulse gas delivery systems in semiconductor fabrication, such as those used in ALD processes, suffer from inaccuracies and repeatability issues due to the reliance on aging shutoff valves, leading to inefficient gas usage and complex adaptive adjustments, and require time-consuming gas charging and stabilization processes.
Innovation Solution
An integrated pulse gas delivery system with a mass flow controller (MFC) and pressure control, utilizing a flow sensor and downstream pressure sensor to independently control gas flow and pressure, reducing the need for shutoff valves and enabling precise mole-based and time-based pulse delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shutoff valves are used to control gas pulses, then gas delivery can be achieved, but pulse accuracy and repeatability degrade with valve aging
Solution Approach 1:
The patent removes the shutoff valve from the gas delivery system entirely, replacing it with a mass flow controller that uses a control valve to modulate gas flow. This extraction of the problematic shutoff valve eliminates the reliability degradation issue while maintaining pulse delivery capability through continuous flow control.
Solution Approach 2:
The patent replaces the mechanical shutoff valve system with an electronic control system using a mass flow controller that employs a control valve actuated by a control signal from a microprocessor. This substitution transitions from mechanical on/off control to electronic modulation control, eliminating wear-related reliability issues.
2Reliability
If shutoff valves are used for pulse delivery, then gas pulsing is achieved, but the system requires complex adaptive adjustments to maintain accuracy
Solution Approach 1:
The patent implements a feedback control system where a flow sensor continuously measures the actual gas flow rate and provides this information to a microprocessor. The microprocessor compares the measured flow to the desired flow rate and adjusts the control valve position accordingly, eliminating the need for complex adaptive adjustments while maintaining pulse repeatability.
Solution Approach 2:
The mass flow controller system is self-regulating, automatically adjusting the control valve position based on real-time flow measurements to maintain the desired flow rate. This self-service capability eliminates the need for external adaptive adjustments or manual calibration, simplifying the control system while improving repeatability.
3Stress or pressure
If gas flow is continuously maintained through leakage lines, then pressure control is achieved, but process gas is wasted
Solution Approach 1:
The patent uses periodic pulsed gas delivery instead of continuous flow through leakage lines. The mass flow controller delivers gas in controlled pulses only when needed for the semiconductor processing step, eliminating continuous gas waste while maintaining proper pressure control during the processing window through precise pulse timing and duration control.
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 achieves improved accuracy, repeatability, and efficiency in gas delivery by eliminating the dependency on shutoff valves, allowing for rapid cycle times and precise control of gas pulses without the need for complex adaptive adjustments.
Implementation Method 1
a flow sensor configured to measure flow rate in the flow channel
Implementation Method 2
a downstream pressure sensor, downstream of the flow sensor and of the control valve, configured to measure gas pressure in the flow channel
Implementation Method 3
a control valve configured to control flow of gas in the flow channel
Data Source
AI summary
Pulsed gas delivery is obtained with mass flow control using a thermal mass flow sensor and control valve. The controller is augmented for pressure control with a downstream pressure sensor. In separate control modes of operation, the control valve is controlled in response to the flow sensor during pulse gas delivery mode and controlled in response to the downstream pressure sensor during pressure control mode of operation.