Secondary Vacuum Chamber Sampling for In-Situ Contaminant Identification
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Solution Overview
Problem
Current methods for measuring contamination in vacuum chambers are inefficient and prone to cross-contamination, especially when dealing with small gas fragments and tight thermal tolerances.
Innovation Solution
A system comprising a primary vacuum chamber, a secondary vacuum chamber connected via a gate valve, a heat exchanger, a gas source, and a sample container, which allows for the adsorption and desorption of contaminants using cooling and heating cycles, followed by gas sample collection and analysis using a mass-spectrometer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a residual gas analyzer (RGA) is used to measure in-situ contamination, then contamination measurement is achieved, but it is difficult to identify contaminants present in small gas fragments from a large and complex chamber
Solution Approach 1:
The patent extracts contaminants from the large primary vacuum chamber by pumping them into a smaller secondary vacuum chamber. This concentration of contaminants in a smaller volume enables more effective analysis by the mass spectrometer, resolving the difficulty of detecting and measuring contaminants in the large primary chamber.
Solution Approach 2:
The system divides the vacuum chamber into two separate chambers: a primary vacuum chamber for maintaining the vacuum environment and a secondary vacuum chamber for contaminant collection and analysis. This segmentation allows the measurement function to be separated from the main vacuum system, improving both measurement precision and reducing interference from the large chamber environment.
2Measurement precision
If a gas column mass-spectrometry (GCMS) system is used to improve detection of contaminants, then detection capability is improved, but the system collects gas samples at elevated temperatures which may not be feasible due to tight thermal tolerances
Solution Approach 1:
The patent separates the heating function from the vacuum chamber by placing it outside the primary chamber. The secondary vacuum chamber can be heated independently for desorption without affecting the thermal environment of the primary chamber, thus improving detection capability while respecting thermal tolerance constraints of chamber components.
Solution Approach 2:
The secondary vacuum chamber acts as an intermediary between the primary vacuum chamber and the mass spectrometer. It provides a controlled environment for heating and desorption that is isolated from the primary chamber, allowing temperature management that satisfies both detection requirements and thermal tolerance constraints.
3Measurement precision
If an ex-situ process using a sample coupon is used to measure contamination, then contamination measurement is achieved, but the process is slow and handling introduces risk of cross-contamination
Solution Approach 1:
The patent extracts contaminants directly from the vacuum chamber environment into the secondary chamber where they are trapped on a cold surface. This eliminates the need for separate sample coupons and ex-situ handling, dramatically reducing collection time and eliminating cross-contamination risks associated with sample handling and transport.
Solution Approach 2:
The system allows the vacuum chamber itself to serve as the source of contaminants for analysis, eliminating the need for separate sample collection mechanisms. The contaminants are pumped directly from the chamber environment and trapped in the secondary chamber, making the measurement process self-contained and eliminating external handling steps.
4Measurement precision
If contaminants are collected in a vacuum chamber, then in-situ measurement is achieved, but the chamber size makes contaminant identification difficult
Solution Approach 1:
The patent segments the vacuum system into a large primary chamber for maintaining vacuum conditions and a small secondary chamber for contaminant collection. This allows in-situ measurement capability while concentrating contaminants in a small volume that is suitable for identification by the mass spectrometer.
Solution Approach 2:
The patent extracts contaminants from the large primary vacuum chamber into the small secondary vacuum chamber. This concentration process overcomes the dilution effect of the large chamber volume, enabling effective contaminant identification while maintaining in-situ measurement capability.
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 system enables efficient collection and identification of contaminants in vacuum chambers, reducing collection time and minimizing the risk of cross-contamination, while maintaining high precision in contamination measurement.
Implementation Method 1
cooling the secondary vacuum chamber with a heat exchanger to adsorb contaminants from the primary vacuum chamber into the secondary vacuum chamber
Implementation Method 2
heating the carrier gas in the secondary vacuum chamber to desorb the contaminants into a gas sample with the carrier gas
Data Source
AI summary
The system includes a primary vacuum chamber and a secondary vacuum chamber connected to the primary vacuum chamber via a gate valve. The gate valve operates between an open position in which the secondary vacuum chamber is in fluid communication with the primary vacuum chamber and a closed position in which the secondary vacuum chamber is sealed from the primary vacuum chamber. A heat exchanger cools the secondary vacuum chamber to adsorb contaminants from the primary vacuum chamber into the secondary vacuum chamber when the gate valve is in the open position. A gas source injects a carrier gas into the secondary vacuum chamber when the gate valve is in the closed position. The heat exchanger also heats the carrier gas in the secondary vacuum chamber to desorb the contaminants into a gas sample with the carrier gas. A sample container collects the gas sample from the secondary vacuum chamber.