Surface and Coatings Technology, 36 (1988) 939 -947 939 A NEW TYPE OF TRANSDUCER FOR PARTIAL PRESSURE CONTROL* C. A. GOGOL and R. MUELLER Leybold Inficon Inc., 6500 Fly Road, East Syracuse, NY 13057 (U.S.A.) (Received April 12, 1988) Summary A new transducer for controlling the partial pressure of sputtering gases is described. Utilizing the electron impact emission spectroscopy (EIES) principle, an instrument capable of operating in a total pressure environ- ment of 100 X iO~ Torr or more with minimum detectable partial pressures to 10’ Torr is described. These capabilities seem ideal for controlling reactive deposition processes utilizing N 2, 02 or hydrocarbons. Because of the high operating pressure capabilities, this transducer does not require the complication of high vacuum pressure reduction and thus eliminates a major source of unscheduled maintenance. The operating principles of EIES and the sensitivities that were de- termined for the various gases tested are described in this paper. The present authors have found the technique to have high stability over extended periods of time (about ± 3.5% over 30 days) and sufficient sensitivity to control processes of present practical interest. In addition to the use for direct partial pressure control the technique has utility for monitoring common residual gases such as H20 and CO2. in an analyzer mode, as a pre- cursor to starting the reactive process. 1. Introduction Over the past several years the present authors have been developing a new technology for partial pressure analysis and control. This technology, based on electron impact emission spectroscopy [1, 2] has a set of unique properties and advantages for the intended applications, e.g. partial pressure control of reactive high rate sputtering [3] and low vacuum gas analysis. Specifically, the advantages are perceived to be as follows. (A) Stability: a long-term constancy far exceeding that demonstrated by other instruments used today. (B) Simplicity: a design that requires no moving parts, no critical voltages and no close tolerances. These all combine to make for an instru- *paper presented at the 15th International Conference on Metallurgical Coatings, San Diego, CA, U.S.A., April 11 - 15, 1988. 0257-8972/88/$3.50 © Elsevier Sequoia/Printed in The Netherlands