ALARM AND CONTROL SYSTEM FOR SEMICONDUCTOR MANUFACTURING PLANTS

Abstract: This invention relates to an alarm and control system which detects leak of processing gas or a fire occurring in manufacturing process in very large-scale integrated circuit manufacturing plants, and adequately controls fire protec­ tion system such as fire extinguishing system and the man­ ufacturing process.

Description: Alarm and Control System for Semiconductor Manufacturing Plants The present invention relates to an alarm and control system for semi-conductor factories or the like which can detect a fire or the leakage of treatment gases which are generated during the manufacturing process in a very large-scale integration (LSI) factory and also suitably controls the. manufacturing process as well as a protection device such as fire extinguishing equipment. In semi-conductor factories for very LSI's, etc. which have recently been making rapid progress, at the time of applying an isolation film to a silicon wafer a silane gas is utilized, but such a treatment gas is not only poisonous, but also dangerous since when the concentration of the gas becomes 2 to 5% or more it reacts to oxygen in the air fn he ed and burns, In fact, a fire has r occurved in a certain LSI factory possibly caused by leakage of this gas, and brought about enormous losses. In view of such a situation the present invention aims at providing an alarm and control system for semi-conductor factories or the like which can instantaneously detect the condition wherein the leaked treatment gases and react to oxygen in the air./. burn generating the also products of combustion and whichSallows to appropriately control the outbreak of a fire before it happens or at its initial stages. The present invention will be explained below in reference to the attached drawings concerning its one embodiment as utilized in a CVD (Chemical Vapor Deposition) apparatus as well as associated apparatuses used at the time of applying an insulation film to a semi-conductor wafer. In Fig. 1, the reference numeral 1 is a silane gas cylinder, 2 is an ammonia gas cylinder, 3 is a housing to house these cylinders, 6 is 4 nitride film forming device (CVD) to form an insulating film on a semi-conductor wafer by supplying silane and ammonia gases through pipes 4 and 5 respectively, 8 is a scaveging device which forcedly oxidizes, namely to treat by combustion the unreacted silane gas discharged from the device 6 through a pipe 7 with oxygen being supplied, 10 is a detection box provided between pipes 9 to monitor the state of the gas to be discharged to an exhaust duct 11 from the scaveging device 8, 12 is a vacuum pump to make the CvD 6 vacuous, and 13 is a vent for room air, and 14 is a damper provided within a pipe 15 connecting the housing 3 with the exhaust duct 11. The housing 3 and the detection box 10 are provided with fire detectors D1 and D2, respectively, to detect the products of combustion which are generated when treatment gases such as silane gas, etc. leak, react to oxygen in the air and burn. In this case, even though as the fire detector to detect the combustion products a photoelectric or ionization type smoke detecor may be utilized. According to the characteristic curves shown in Fig. 3 wherein the outputs of the detectors and the concentration of the products of combustion are illustrated on the ordinate and the abscissa, respectively, the sensitivity of the ionization type smoke detector b to the combution products of silane gas is higher than that of a photoelectric type smoke detector g, and the former can detect of the EMI3.1 <tb> combSion <tb> products EMI3.2 earlier than the latter. As shown in Fig. 2 the fire detector D1 mounted within the housing 3 is directly connected to an OR-circuit, OR, while the fire detector D2 installed in the detection box 10 is connected to the OR through an inverter I, the output of the OR being connected to a relay means not Shown which appropriately controls the manufacturing process of the semi-conductors, or a protection device such as a fire alarm, a fire extinguishing device or the like. Operation of the system described above is as follows. The itride-. film forming device 6 has semi-conductor wafers contained therein, and after it is made vacuous by the vacuum pump 12, the silane and ammonium gas cylinders 1 and 2 are opened to supply the silane and ammonia gases to the device 6, whereby nitride films necessary for the semiconductor wafers, i. e. insulating films are made to be generated thereon. The gases which contain the unreacted gases after the treatment are forcibly oxidized in the scaveging device 8 and discharged from the exhaust duct 11 through the pipe 9 as a safe gas. In this state, if the silane gas leaks from the silane gas cylinder 1, reacts with oxygen in the air and burns the fire detector D1 is operated by the products of combustion tocperate through the OR-circuit OR, a relay means not shown which controls a protection device such as a fire alarm, a fire extinguishing device or the like, or controls the damper 14 so as to be opened fully to discharge the leaked gases to the exhaust duct 11, or to control the manufacturing process. As to the detection box 10, during the normal operation of the sczveging device 8, since the burned products of combustion are discharged to the exhaust duct 11 through the pipe 9, the fire detector D2 does not operate the OR-circuit OR by the action of the inverter I. However, if the scaveging device 8 is damaged, and the untreated silane gas is discharged EMI5.1 tithe fire detector D2 operates the OR-circuit OR by action of the inverter I, EMI5.2 EMI5.3 EMI5.4 and a protection device such as a fire alarm or a fire extinguishing device or the like not shown, or a relay means to control the manufacturing process. As stated above the present invention reveals such an effect that it provides an alarm and control system for semi-conductor factories or the like in which since at locations where poisonous and inflammable treatment gases are used as in the manufacturing process of semi-conductors gas detectors are provided to detect the existence of the products of combustion generated by combustion of the treatment gases an appropriate control can be carried out before the occurrence of or at the early stages of a fire. 4. Brief Description of the Drawings Fig. 1 is a schematical view of one embodiment of the present invention, Fig. 2 is its circuit diagram, and Fig. 3 is the characteristic curves of photoelectric type and ionization type smoke detectors.

Claims: Claims 1. An alarm and control system for semi-conductor factories or the like characterized in that locations where poisonous and inflammable treatment gases such as silane gas, etc. are used as in the manufacturing process of semi-conductors, etc. fire detectors are provided to detect the products of combustion that are generated as the result of te leakage of said treatment gases, their reaction with oxygen in the air and their combustion, and that the change in output of said fire detectors causes an alarm to issue and the control of protection device such as a fire extinguishing device as well as the control of said manufacturing process of said semi-conductors, etc. 2. An alarm and control system for semi-conductor factories or the like as claimed in claim 1 wherein a fire detec-tor equipped with an inverter on its output said is provided on the secondary side of a scaveging device, 3. An alarm and control system for semi-conductor factories or the like as claimed in claim 1 wherein said fire detector is installed ina housing in which cylinders containing said treatment gases are housed. 4. An alarm and control system for semi-conductor factories or the like as claimed in any one of claims 1 to 3 wherein said fire detector is an ionization type smoke detector.

Inventors: KIMURA, SHOICHI C/O NOHMI BOSAI KOGYO CO., LTD.
Applicants: NOHMI BOSAI KOGYO CO., LTD.
Application year: 1983
Main classification: G08B17
IPC codes: G08B17, A62C3