How to Reduce Outgassing, Improve Processing in High Vacuum Manufacturing Processes

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Presented At The American Vacuum Society

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Outgassing Characterization of Elastomeric Seals Used in Semiconductor Wafer Processing

Semiconductor wafer processors who need to reduce the effect of outgassing from sealing materials in high vacuum environments will benefit from recent testing conducted by DuPont Performance Elastomers (DPE). In a DPE technical paper titled, "Outgassing Characterization of Elastomeric Seals Used in Semiconductor Wafer Processing," presented Nov. 9 at the American Vacuum Society (AVS) in San Jose, Calif., DPE reviews a testing protocol for elastomers that demonstrates that outgassing can be significantly reduced by selecting sealing materials that have been appropriately developed and tested for minimal outgassing.

High or ultra-high vacuum environments have been identified as a potential cause for concern for chip manufacturers. In high vacuum environments, controlling the uniformity of the environment within the vacuum chamber is critical to the effectiveness of the deposition process, as outgassing from elastomer seals can be absorbed by the substrate and interfere with the deposition process.
Testing Protocol - The First of Its Kind

Since there is no ASTM or SEMI standard routinely used to characterize elastomer outgassing, DPE developed test equipment and procedures capable of evaluating elastomers typically used in semiconductor processing applications. Three commonly used sealing materials: fluoroelastomers (FKM), perfluoroelastomers (FFKM), and silicone (VMQ) were exposed to the same vacuum conditions and the results compared. Characteristics measured include total outgassing rate as a function of temperature, total outgassing rate as a function of time at a given temperature, and an analysis of evolved gas species.

The results indicate that perfluoroelastomers offer the lowest outgassing, especially at elevated temperatures, but performance can vary within classes of elastomers due to variations in compound formulation. Results from DPE testing will assist equipment and process engineers to characterize outgassing from elastomer seals, and more importantly, help them choose elastomer materials that are designed with low-outgassing characteristics. To request a copy of the paper, contact DuPont Performance Elastomers.

DuPont Performance Elastomers, a global supplier of specialty elastomers with headquarters in Wilmington, Del., is a wholly-owned subsidiary of DuPont. The company is an industry leader in chloroelastomers and fluorinated elastomers, serving the automotive, chemical, petrochemical, semiconductor, food and pharmaceutical processing, construction, general rubber and wire and cable industries.

For more than 75 years, product development and technical expertise have helped introduce a broad product offering across major semiconductor processes. DuPont Performance Elastomers has integrated manufacturing back to the polymer, enhancing quality control and product development. Kalrez® perfluorelastomer parts are manufactured in ISO 9000 registered facilities and are available in a wide variety of finished products from conventional seal shapes and bonded door seals to custom geometrics. Kalrez® parts are specially cleaned and double packaged in Class 100 workstations to significantly reduce the potential for contamination. Each item is individually packaged in a bar-coded bag for full traceability and is available as O-rings, sheets, and custom parts.

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DuPont is a registered trademark of DuPont and its affiliates.
Kalrez® is a registered trademark of DuPont Performance Elastomers


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Nancy Harton
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