Mixed Gas Supply Device Back-Diffusion Prevention
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Solution Overview
Problem
Conventional mixed gas supply devices for semiconductor manufacturing apparatuses face challenges in preventing backflow and back-diffusion, particularly when a low flow rate gas line is located upstream of a high flow rate gas line, leading to prolonged gas displacement times and reduced process efficiency.
Innovation Solution
The mixed gas supply device rearranges gas supply lines to position the low flow rate gas line close to the mixed gas outlet, with an orifice for back-diffusion prevention at the outlet side switching valve, and uses a flow rate control device with a small hole portion to prevent back-diffusion and facilitate rapid gas displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the low flow rate gas line is positioned upstream of the high flow rate gas line, then backflow prevention is easier, but gas displacement time increases and productivity decreases
Solution Approach 1:
The patent inverts the conventional gas line arrangement by positioning the low flow rate gas line downstream (close to the mixed gas outlet) rather than upstream. This reversal enables faster gas displacement while back-diffusion prevention orifices are strategically placed at critical points to prevent gas mixing in the reversed configuration.
Solution Approach 2:
Back-diffusion prevention orifices are introduced as intermediary elements at the outlet side of the low flow rate gas line and at the inlet side of the high flow rate gas line. These orifices act as mediators that allow gas flow control while preventing back-diffusion, enabling the inverted line arrangement to function reliably.
2Speed
If switching valves are operated simultaneously to change gas species, then switching speed is maximized, but backflow and back-diffusion occur between gas lines
Solution Approach 1:
The patent implements a standardized orifice structure that is copied and installed at multiple critical locations: at the outlet side of each low flow rate gas line's switching valve and at the inlet side of each high flow rate gas line's switching valve. This replicated orifice design ensures consistent back-diffusion prevention across all gas lines during simultaneous switching operations.
3Adaptability or versatility
If the number of gas supply lines is increased to provide more gas species, then processing capability improves, but apparatus size and complexity increase
Solution Approach 1:
The patent creates a universal gas supply line configuration where each line (regardless of flow rate) follows the same structural pattern: flow rate control device, switching valve, and back-diffusion prevention orifice. This modular, multi-functional design allows easy addition of gas lines while maintaining consistent back-diffusion prevention across the entire system.
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 configuration enables faster gas displacement and prevents back-diffusion, improving semiconductor manufacturing productivity and gas utilization efficiency while simplifying the apparatus structure and assembly.
Implementation Method 1
an orifice for back-diffusion prevention at the outlet side switching valve
Implementation Method 2
a flow rate control device with a small hole portion to prevent back-diffusion
Data Source
AI summary
A mixed gas supply device includes a plurality of gas supply lines arranged in parallel that include flow rate control devices and outlet side switching valves, wherein gas outlets of respective outlet side switching valves communicate with a manifold, and another gas supply line at a position close to a mixed gas outlet of the manifold supplies a low flow rate gas, wherein an outlet side of the flow rate control device and an inlet side of the outlet side switching valve are hermetically connected via an outlet side connecting fitting of the flow rate control device and a mounting table having a gas passage, wherein a small hole portion is provided at a part of a flow passage at the outlet side connecting fitting and/or a flow passage, which makes the outlet side switching valve and a mixed gas flow passage in the manifold communicate with one another.