[54] PROCESS GAS DISTRIBUTION SYSTEM AND METHOD WITH AUTOMATIC TRANSDUCER ZERO CALD3RATION
[75] Inventors: Dennis A. Sierk; Ronald R. DuRoss, both of Huntsville; Stephen G. Geist, Union Grove, all of Ala.; Gregory L. Hayes, Fayetteville, Term.
[73] Assignee: SCI Systems, Inc., Huntsville, Ala.
[21] Appl. No.: 242,805
[22] Filed: May 13,1994
Related U.S. Application Data
[60] Continuation of Ser. No. 3,583, Jan. 13, 1993, abandoned, which is a division of Ser. No. 576,067, Aug. 31, 1990, Pat. No. 5,220,517.
[51] Int. CI.6 G01F 25/00; G01G 23/01
[52] U.S. CI 364/571.01; 73/1 B; 364/550
[58] Field of Search 364/138, 550,
364/551.01, 558, 567, 571.01, 571.04, 571.05, 509, 556, 510, 571.07; 141/65, 83; 73/4 R, 1 G, 1 B, 708
[56] References Cited
U.S. PATENT DOCUMENTS 4,241,407 12/1980 Sookikian et al 364/571.05 X
Primary Examiner—Edward R. Cosimano
Assistant Examiner—Edward Pipala
Attorney, Agent, or Firm—Curtis, Morris & Safford
[57] ABSTRACT
A system including a plurality of gas flow control units in cabinets which are connected to distribute process gas, on demand, to a plurality of utilization locations known as "tool" locations in a semi-conductor manufacturing plant. Transducers are used in the system to measure pressures and other control parameters. Zero calibration of the transducers is provided by automatically subjecting each transducer to a reference computer routine to compute the difference between the standard value and the transducer output, and store the difference as an "offset" to correct the output of the transducer. Thus, re-calibration is performed simply and quickly, at a relatively low labor cost and with relatively little downtime for the system.
