Gas Flow Controller In Situ Testing via Upstream Pressure Drop
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Solution Overview
Problem
Conventional methods for testing gas flow through mass flow controllers in semiconductor manufacturing are inefficient, prone to inaccuracies due to drift, and require costly, sophisticated pressure regulators, which are not commonly used in existing systems, leading to limited adoption in the industry.
Innovation Solution
A method that measures the rate of pressure drop upstream of a gas flow controller to determine the gas flow rate without the need for special pressure regulators, allowing for continuous operation and integration with existing semiconductor tools by controlling the timing of valve closure and pressure rise to maintain constant flow rates, and using standard pressure regulators with temporary adjustments to achieve accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pressure rise measurement method is used in process chamber, then gas flow rate can be determined, but throughput is reduced due to loss of productive processing time
Solution Approach 1:
The system divides the measurement function from the process chamber by introducing a separate measurement volume upstream. This segmentation allows the process chamber to continue productive operations while flow measurements are performed in the dedicated measurement volume, eliminating throughput loss.
Solution Approach 2:
A separate measurement volume acts as an intermediary between the gas source and the process chamber. This intermediate volume enables flow measurements without requiring the process chamber to be taken offline, thus maintaining productivity while achieving measurement objectives.
2Measurement precision
If conventional pressure rise measurement is used in process chamber, then gas flow can be measured, but accuracy is compromised due to adsorption/desorption of gases by chamber wall deposits
Solution Approach 1:
The measurement function is extracted from the process chamber environment and placed in a separate measurement volume. This extraction removes the measurement process from the harmful environment of chamber wall deposits, eliminating adsorption/desorption interference and improving measurement accuracy.
Solution Approach 2:
The separate measurement volume serves as an intermediary that isolates the measurement process from harmful chamber wall deposits. This intermediate environment prevents direct interaction between measuring gases and adsorptive surfaces, ensuring accurate measurements.
3Measurement precision
If conventional pressure rise measurement is used, then gas flow rate can be determined, but accuracy is affected by reactions between gases and materials on chamber walls
Solution Approach 1:
The measurement process is extracted from the process chamber where reactive deposits are present. By performing measurements in a separate, clean measurement volume, the harmful chemical reactions between process gases and chamber wall materials are eliminated, ensuring accurate flow rate calculations.
4Measurement precision
If process chamber volume is used for measurements, then flow rate can be calculated, but accuracy is compromised when chamber volume changes due to component additions or removals
Solution Approach 1:
The system segments the measurement function into a dedicated measurement volume that is separate from the process chamber. This separate measurement volume has stable, well-defined boundaries that do not change with process chamber component modifications, ensuring consistent and accurate flow rate calculations.
Solution Approach 2:
A stable measurement volume acts as an intermediary with fixed, known boundaries. This intermediate volume provides a consistent measurement environment that is unaffected by changes in the process chamber configuration, enabling reliable flow rate measurements.
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
Enables accurate and efficient measurement of gas flow rates in standard industrial processes, such as semiconductor manufacturing, without the need for sophisticated pressure regulators, allowing for continuous operation and integration with existing systems, thus improving process efficiency and reducing costs.
Implementation Method 1
measuring a rate of pressure drop in the volume
Data Source
Figure 1
Figure 2
Figure 2A~2B
AI summary
Methods and apparatus utilize a rate of drop in pressure upstream of a gas flow controller (GFC) to accurately measure a rate of flow through the GFC. Measurement of the gas flow through the many gas flow controllers in production use today is enabled, without requiring any special or sophisticated pressure regulators or other special components. Various provisions ensure that none of the changes in pressure that occur during or after the measurement perturb the constant flow of gas through the GFC under test.