Sensor Technology 9 Environmental Operating Envelope


The new sensors offer better output level stability, responsiveness and overall performance in the aggressive atmospheres in which they are required to work. The output level from the sensors is fundamentally stable when exposed to the wide variations in operating temperature, relative humidity and gas flow rates that will be encountered during normal operation; in particular, the sensors perform well in the typical high temperature, low humidity and high gas flow rate environment that is characteristic in a semiconductor foundry.


Cross-Contamination Sensitivity


properties of the electrolyte result in more stable performance in the high flow, low humidity and high temperature conditions that are typical to semiconductor applications.


Since ionic liquids have a very low vapour pressure, they are far less susceptible to drying out over time than traditional gel electrolyte systems, a significant factor for applications in the semiconductor industry, where the detectors are typically mounted in ducts monitoring a constant flow of hot dry gas. The stability of the new ionic liquid electrolyte sensors, both over time and in aggressive atmospheres where temperature and humidity can rapidly change, is greatly enhanced.


For applications where hydrogen sulfide (H2S) is present or for instruments that are calibrated with H2S gas, a filtered version of the ionic liquid based hydride sensors are also available.


Cross sensitivities are extremely good, with no significant response to a wide range of gases that may be present in the monitored environment. Versions of the arsine and phosphine sensors fitted with a 200ppm hour capacity H2S filter are available on a customer by customer basis if required.


The new sensors have been extensively tested for exposure to IPA, isopropyl alcohol, which is widely used as a cleaning agent, and there is no effect on sensor output level during exposure to the cleanser.


Hydride gases in the semiconductor industry are typically diluted with hydrogen when fed to epitaxial reactors. Cross sensitivity tests on new hydride sensors show zero cross sensitivity to hydrogen, eliminating the likelihood of false alarms.


Conclusions


The semiconductor and photovoltaic cell manufacturing industries are key enabling technologies for both the developed and developing worlds. In addition to providing the foundation of today’s high technology digital infrastructures, the increased use of carbon-free power generation, on a micro and macro scale is critical to reducing the environmental impact of human activity.


In a small but critical way, the latest developments of the Sensoric range of sensors play their part in improving the efficiency of the core manufacturing technologies. By delivering improvements in the performance of existing arsine and silane sensors, and introducing sensors for a further two widely-used hydrides used in the semiconductor and increasingly; the photovoltaic manufacturing industries, these industry become safer places to work.


Operating Life


In previous gel-based arsine, silane and phosphine sensors, operational life was restricted because of the tendency for the gel to dry out. The liquid electrolyte replacements overcome this problem, reducing the lifetime cost of ownership.


With a commitment to continuous improvements in quality and sensors that detector more exotic gases than anyone else, the introduction of these new toxic gas sensor designs further reinforces City Technology’s position as the world’s leading, and most innovative manufacturer of exotic gas sensors for life safety and facility protection applications.


AUTHOR DETAILS


Gintare Budriunaite Product Specialist City Technology Limited


City Technology Centre Walton Road Portsmouth PO6 1SZ Tel: + 44 2392 325511 Fax: + 44 2392 386611 Email: sensors@citytech.com Web: www.citytech.com


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