Cycling Valves for Precise Gas Flow Control in Beam Processing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gas injection systems for beam processing systems have limited control over gas flow and pressure in the sample chamber, requiring frequent refilling, coarse flow control, and safety concerns due to hazardous chemicals, with limited ability to maintain precise ratios of process gases.
Innovation Solution
The implementation of cycling valves for each gas source, with microvalves positioned inside the vacuum chamber for rapid response, and gas sources external to the vacuum system for easy connection and disconnection, allowing precise control of gas flow by adjusting the duty cycle and frequency of the valves, eliminating the need for flow-limiting apertures and enabling rapid pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a crucible with plunger valve is used to store and deliver precursor gas, then gas flow can be controlled by heat and valve positioning, but the crucible requires frequent refilling and realignment, and safety equipment is needed for hazardous chemicals
Solution Approach 1:
The gas delivery system is segmented into multiple independent gas sources, each with its own cycling valve, rather than using a single crucible. This allows continuous operation as one source can be refilled while others are in use, eliminating downtime and frequent interruptions.
Solution Approach 2:
The precursor gas sources are extracted from the vacuum chamber and placed outside in a cabinet. This eliminates the need for frequent refilling operations inside the vacuum chamber and allows safe handling of hazardous chemicals outside the beam path.
2Ease of operation
If a diaphragm valve with stepper motor is used to control gas flow, then flow rate can be adjusted, but the control is coarse and pressure regulation is limited
Solution Approach 1:
The system uses cycling valves that dynamically adjust gas flow by varying the duty cycle (percentage of time valve is open) and frequency of operation. This provides continuous, precise control over gas flow rates and chamber pressure, replacing the coarse static control of traditional diaphragm valves.
Solution Approach 2:
The valve operation parameters (duty cycle and frequency) are changed to precisely control gas flow. By adjusting these parameters, the system achieves fine control over precursor gas delivery and chamber pressure, enabling precise process control.
3Stress or pressure
If flow-limiting apertures are used to maintain low pressure in the sample chamber, then pressure control is achieved, but the time to bring the chamber up to operating pressure increases
Solution Approach 1:
The cycling valves provide dynamic control of gas flow into the chamber, allowing rapid adjustment of flow rates. This eliminates the need for fixed flow-limiting apertures and enables quick pressure ramp-up when needed, while maintaining precise pressure control during operation.
4Ease of manufacture
If the gas source is positioned inside the vacuum chamber, then gas delivery is direct, but refilling requires entry into the chamber and realignment of the needle
Solution Approach 1:
The gas sources are extracted from the vacuum chamber and placed in a cabinet outside the chamber. This allows refilling and source replacement to be performed externally without breaking vacuum or entering the chamber, eliminating realignment requirements and improving safety.
Solution Approach 2:
A cabinet serves as an intermediary between the external environment and the vacuum chamber, housing the gas sources and control valves. This intermediary structure allows easy access for refilling while maintaining vacuum integrity in the chamber.
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 provides precise and rapid control of gas flow and pressure in the sample chamber, reducing the need for frequent refilling, enhancing safety, and allowing a wider range of pressures and flow rates, while maintaining precise gas ratios, thus improving the efficiency and safety of beam-assisted processes.
Implementation Method 1
gas flow from multiple gas sources into a sample chamber of a beam system is controlled by a cycling valve for each gas source
Implementation Method 2
microvalves positioned inside the vacuum chamber for rapid response
Implementation Method 3
allowing precise control of gas flow by adjusting the duty cycle and frequency of the valves
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Gas flow from multiple gas sources into a sample chamber of a beam system is controlled by a cycling valve for each gas source, with the gas pressure in the sample chamber being determined by the relative time that the valve is opened and the upstream pressure at the valve. A gas valve positioned inside the vacuum chamber allows rapid response in shutting off a gas. In some preferred embodiments, a precursor gas is supplied from a solid or liquid material in a container that remains outside the vacuum system while in use and which is readily connected or disconnected to the gas injection system without significant leakage.