FOUP Gas Sampling Interface for Trace Wafer Contamination
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Solution Overview
Problem
Current contamination monitoring methods in semiconductor and microelectromechanical system fabrication processes are inadequate for detecting low-level gaseous contamination in substrate wafers and transport enclosures, leading to potential defects and reduced service life of semiconductors and microsystems, as they lack real-time detection capabilities and sensitivity to trace amounts of contaminants.
Innovation Solution
A device with a gas analyzer capable of ionizing gases at atmospheric pressure, connected via an interface to the internal atmosphere of transport enclosures, allowing real-time analysis of gases and detecting low concentrations of contaminants, using ion mobility or mass spectrometry techniques, with an interface made of perfluoroalkoxy material to minimize gas adsorption and ensure accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If standard measuring devices are used in transport enclosures, then the device size fits within the enclosure, but the measurement precision for trace gaseous contamination deteriorates
Solution Approach 1:
The gas analyzer is extracted from the transport enclosure and placed externally, with only the sampling interface remaining inside. This allows the use of high-precision analytical instruments that would be too large for the enclosure while maintaining the ability to measure contamination at 1 ppb levels through direct sampling of the internal atmosphere.
Solution Approach 2:
A sampling interface acts as an intermediary between the transport enclosure interior and the external gas analyzer. This interface includes a sampling probe or port that transfers gas samples from the enclosed space to the analysis instrument, enabling precise measurements without requiring the entire analyzer to fit within the limited enclosure volume.
2Quantity of substance
If global atmosphere monitoring in white room is performed, then the overall contamination level is monitored, but the contamination specific to transport enclosures is not diagnosed
Solution Approach 1:
The monitoring system transitions from global white room atmosphere monitoring to localized measurement within each transport enclosure. The sampling interface is designed to extract gas samples specifically from the enclosure interior, enabling detection of local contamination sources such as process gases from wafers and contaminants concentrated in the porous enclosure environment.
Solution Approach 2:
The monitoring system is segmented to allow individual measurement of each transport enclosure rather than measuring the collective white room atmosphere. Each enclosure can be sampled independently through its own interface, enabling identification of contamination in specific enclosures that would be diluted and undetectable in global measurements.
3Measurement precision
If measurement time is extended to collect sufficient contaminant mass, then the detection sensitivity improves, but real-time monitoring capability deteriorates
Solution Approach 1:
The measurement system changes the parameter of sampling flow rate to achieve rapid collection of sufficient contaminant mass. By using a controlled gas flow through the sampling interface, the system can concentrate contaminants quickly and deliver them to the analyzer for immediate detection, achieving both high sensitivity and real-time monitoring capability.
Solution Approach 2:
The system performs preliminary concentration of contaminants by directing gas flow through the sampling interface before analysis. This preliminary action accumulates sufficient contaminant mass in the sampling line or detector cell quickly, enabling rapid detection without requiring extended measurement times.
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 real-time detection and measurement of trace gaseous contamination at 1 ppb levels, reducing the risk of defects in semiconductors and microsystems by analyzing the atmosphere closest to the substrates without additional contamination from adsorption polymers, and providing a more sensitive and accurate assessment of contamination levels within transport enclosures.
Implementation Method 1
a gas analyzer including means for ionizing gases and means for identifying the ionized gases by measuring a parameter of the ions
Implementation Method 2
an interface made of perfluoroalkoxy material to minimize gas adsorption
Data Source
AI summary
A device is used to measure contamination directly in transport enclosures of FOUP or SMIF type, for example. The transport enclosure is placed on an adapter that sets up direct communication between it and an external gas analyzer. The gas analyzer ionizes the sampled gases and performs the analysis by measuring a parameter of the ions resulting from this ionization. This measures very low levels of gaseous contamination in real time.