Airborne Contamination Sampling Line Balancing for True Mean Measurement
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Solution Overview
Problem
Current airborne molecular contamination measurement stations in semiconductor clean rooms face challenges in detecting abnormal concentrations of gaseous species across multiple zones simultaneously due to disparities in sampling line conductances, leading to inconsistent measurements and delayed detection of potential contamination risks.
Innovation Solution
A method for setting the conductances of controllable restrictions in the measurement station, where the conductance of each sampling line is adjusted to match the maximum conductance of the line with the lowest initial conductance, ensuring balanced contributions from all lines during simultaneous measurements, using a combination of initial identification and conductance-setting steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If simultaneous measurement in multiple sampling lines is performed, then detection speed is improved, but measurement precision deteriorates due to conductance disparities
Solution Approach 1:
The patent applies parameter changes by adjusting the conductance of controllable restrictions in each sampling line to compensate for length disparities. By modifying the conductance parameter of each line individually, the system achieves balanced gas flow contributions from all sampling lines, thereby maintaining measurement precision while enabling simultaneous multi-zone detection
Solution Approach 2:
The patent implements preliminary action through an initial identification step that determines the conductance characteristics of each sampling line before actual measurements begin. This preliminary characterization allows the system to pre-adjust conductance settings, ensuring that all lines contribute equally to the measurement from the start, thus eliminating the need for sequential adjustment during operation
2Measurement precision
If sequential measurement of test zones is performed, then measurement precision is maintained, but productivity deteriorates due to delayed detection
Solution Approach 1:
The patent merges multiple sampling lines into a common measurement system, allowing simultaneous sampling from multiple test zones to be analyzed by a single gas analyzer. This combining approach enables parallel data acquisition from different zones, dramatically improving productivity and detection speed while maintaining measurement precision through the conductance balancing mechanism
Data Source
AI summary
A setting method includes setting the conductances of the controllable restrictions of an airborne molecular contamination measurement station. The setting method includes an initial identification step, prior to the carrying-out of an airborne molecular contamination measurement step, and during which the sampling line that has the lowest conductance when the conductance of the controllable restriction of the said sampling line is set to its maximum value is determined, and an initial conductance-setting step prior to the carrying-out of the measurement step and after the initial identification step, and during which the conductances of the controllable restrictions are set to make them correspond to the lowest conductance determined in the initial identification step. Further, a measurement station is provided for measuring airborne molecular contamination.