AVS 51st International Symposium
    Exhibitor Workshop Tuesday Sessions
       Session EW-TuL

Paper EW-TuL5
Triple Gauge, A New Combination Vacuum Gauge

Tuesday, November 16, 2004, 1:20 pm, Room Exhibit Hall B

Session: Innovations in Vacuum Techniques and Measurements
Presenter: M. Wuest, INFICON Ltd, Liechtenstein
Authors: M. Wuest, INFICON Ltd, Liechtenstein
R. Enderes, INFICON Ltd, Liechtenstein
U. Waelchli, INFICON Ltd, Liechtenstein
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We have developed a new type of combination vacuum total pressure gauge. The gauge combines a Bayard-Alpert, a Pirani and, as a novelty, a capacitive diaphragm gauge (CDG) in one housing of less than 30 mm diameter and 60 mm in length. Up to now this was the size of the most modern Pirani Bayard-Alpert gauges. The gauge has a large measurement range from 5*E-10 mbar to 1500 mbar. Compared to the previous Bayard-Alpert Pirani combination gauge, the addition of a CDG provides gas type independent pressure measurement above 10 mbar. This solves venting problems with different gas types such as argon or helium and is therefore ideal for load lock applications. The integrated Pirani sensor protects the yttrium oxide coated iridium filament of the Bayard-Alpert gauge from premature burnout and bridges the pressure range between the Bayard-Alpert (5*E-10 mbar to 1*E-2 mbar) and the CDG measurement range (10-1500 mbar). This new combination is realized thanks to a novel miniature ceramic CDG. The 11 mm diameter alumina CDG has a reference vacuum in the 1*E-4 mbar range. The pressure is sensed by measuring the deflection of an 80 micrometer thick diaphragm over a gap distance of 15 micrometer. The resolution is 0.2% of measured value over a range of 100-1500 mbar. In addition, one version of the gauge includes an absolute atmospheric pressure sensor for even more accurate load-lock application. A combination gauge saves cost for the original equipment manufacturer as it reduces system requirements such as the number of flanges and cables required as well as software interfaces and testing time. We will give an overview of the sensing principles and sensors involved and present pertinent specifications of the gauge.