Reverse Flow Gas Gauge Proximity Sensor Bandwidth
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Solution Overview
Problem
Traditional gas gauge proximity sensors in semiconductor lithography face challenges in achieving high bandwidth due to slow pressure propagation against gas flow, leading to increased response time and reduced accuracy, especially when dealing with exotic materials like Gallium Arsenide and Indium Phosphide.
Innovation Solution
A reverse flow gas gauge proximity sensor design is implemented, featuring an injection chamber and a measurement chamber with apertures close to the substrate surface, where gas flow from the injection chamber enters the measurement chamber, allowing pressure changes to propagate with the flow, enhancing response time and bandwidth by stabilizing transient behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional outward gas flow is used in gas gauge proximity sensors, then the sensor can measure proximity accurately, but the response time increases and bandwidth decreases due to slow pressure propagation against gas flow
Solution Approach 1:
The patent inverts the traditional gas flow direction in the measurement nozzle. Instead of gas flowing outward from the measurement surface into the ambient environment (traditional design), the gas flow is reversed to flow from the ambient environment through the measurement nozzle toward the measurement surface. This inversion allows pressure changes to propagate with the gas flow direction rather than against it, significantly reducing response time and increasing bandwidth while maintaining measurement accuracy
2Measurement precision
If lower pressure operation is used to reduce gas flow rate, then measurement accuracy may improve, but response time constant increases due to increased resistance to pressure propagation
Solution Approach 1:
By reversing the gas flow direction through the measurement nozzle, the patent enables pressure changes to propagate in the same direction as gas flow rather than against it. This eliminates the resistance effect that normally increases response time at lower pressures, allowing the sensor to maintain fast response times even when operating at lower pressures for improved measurement accuracy
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 reverse flow design significantly improves the response time and bandwidth of the proximity sensor, enabling more accurate and rapid proximity measurements without sacrificing the benefits of gas gauge sensors, particularly in semiconductor lithography applications.
Implementation Method 1
gas flow from the injection chamber enters the measurement chamber, allowing pressure changes to propagate with the flow
Implementation Method 2
pressure sensor coupled to the injection chamber and the measurement chamber. The pressure sensor may be configured to output a signal responsive to a difference in the pressure of gas in the injection chamber and the pressure of gas in the measurement chamber
Data Source
AI summary
A gas gauge proximity sensor supplying gas in a reverse flow direction from the injection chamber to the measurement chamber. Supplying gas in a reverse flow direction enables the transient behavior in the sensor to more rapidly stabilize, with a resulting increase in bandwidth. Optionally, a scavenger chamber can be used to remove the excess gas by locating a scavenger aperture of the scavenger chamber in close proximity to the exit aperture of the injection chamber. A bridge proximity sensor can be used with a reference chamber to receive gas flow from a location close to the exit aperture of the injection chamber in order to reduce common mode errors.