Abstract:
A leak sensor and a leak sensing system are provided. The leak sensor preferably includes a fluid sensing member that is capable of sensing and indicating the presence of a fluid leaked from a fluid storage or transport member. The leak sensor further preferably includes at least two wires communicating with the fluid sensing member. The wires are preferably configured to be short-circuited when they contact the fluid leaked from the fluid storage or transport member. An electrical signal corresponding to a leak sensor location can thereby be sent to a control terminal of the leak sensing system. A portion of the wires may be arranged in a cable coated with a protective material such as Teflon®. The control box (or terminal) preferably receives electrical signals from a plurality of leak sensors. The electrical signals can provide information on whether the fluid has leaked and on which leak sensor or sensors have detected the fluid leak.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This U.S. non-provisional patent application claims priority under 35 U.S.C. §119 from Korean Patent Application 2005-60428 filed on Jul. 5, 2005, the contents of which are hereby incorporated herein by reference in their entirety. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to leak detection systems for semiconductor processing equipment. More specifically, the present invention is directed to a leak sensor capable of indicating constituents of chemical leaks as well as a leak sensing system using leak sensors. 
   With the recent trend toward higher density semiconductor devices and an increasing number of processes, it is desirable to have more efficient and higher quality semiconductor manufacturing processes. Enhancement of the process quality, however, is highly dependent on improvement in the functionality and performance of the semiconductor manufacturing apparatuses and equipment used in these processes. Such apparatuses and equipment include, for instance, wastewater treatment equipment and chemical supply equipment. Chemical supply equipment can include pipes configured to supply various chemicals (e.g., photoresist and cleaning solution) to a semiconductor manufacturing apparatus. 
   In order to perform the semiconductor manufacturing processes, various equipment is connected to the semiconductor apparatus. Unfortunately, accidents frequently result from leakages occurring at equipment connection points. Although environmental safety patrols may occasionally be conducted to detect and prevent accidents caused by such leakages, it is generally difficult for people to detect minute leakages. Operators (and particularly those operators with a limited understanding of the chemicals being used) may therefore be inadvertently exposed to the chemicals. Furthermore, if the leakage is not detected and suppressed at an early stage, multiple accidents may be caused from the leakages. These accidents may include secondary or tertiary accidents from electric cables or other equipment and facilities that are damaged by the chemical leakage. As a result, semiconductor manufacturing lines may be required to be stopped for prolonged periods of time while the failure points are determined and the necessary repairs are conducted. 
   Some conventional leak sensing systems use a point-type leak sensor that emits a light and calculates the intensity of light reflected back to the sensor to determine when a leakage occurs. Other conventional leak sensing systems may use a wire-type leak sensor. There are two kinds of wire-type leak sensors. One wire-type leak sensor incorporates a two-wired cable that is short-circuited when a leakage occurs to sense the leakage. The other wire-type leak sensor includes a cable, wherein a resistance of the cable is determined to sense the occurrence of a leakage. 
   Unfortunately, conventional leak sensors are generally installed in a semiconductor apparatus or a valve box, and they are therefore unable to sense a leakage of a utility pipe. They are also generally unable to detect the kind of chemical leaked. Moreover, the light emitted by a point-type leak sensor may be absorbed by the leakage, thereby reducing the intensity of the light reflected back to the sensor. The point-type leak sensor may therefore not be able to adequately sense the occurrence of the leakage. 
   SUMMARY OF THE INVENTION 
   Exemplary embodiments incorporating principles of the present invention provide a leak sensor and a leak sensing system. In an exemplary embodiment, for instance, the leak sensor may include a fluid sensing member capable of sensing and indicating the presence of a fluid leakage. Two or more wires may further be combined within the fluid sensing member. 
   In another exemplary embodiment, the leak sensor may include a film that is capable of visually indicating the presence of a fluid that is leaked from a pipe through which the fluid flows. The film preferably encircles a circumference of the pipe and at least two wires may be incorporated in the film. The wires are preferably configured to be short-circuited by contact with the fluid leaked from the pipe. 
   In a further exemplary embodiment, the leak sensing system may include a plurality of fluid sensors. The fluid sensors are preferably arranged to encircle a pipe through which a fluid flows at multiple locations along the pipe where leaks are likely to occur. The fluid sensors are preferably configured to visually indicate when the fluid is leaked from the pipe. A plurality of cables are also preferably provided in conjunction with the plurality of fluid sensors to electrically indicate the presence of a fluid leakage from the pipe. A control box is further preferably electrically connected to the plurality of cables to receive information from the cables that indicates when and where a fluid leakage occurs. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The principles and features of the present invention will now be described more fully hereinafter with reference to the accompanying drawings showing various exemplary embodiments thereof, in which like numbers represent like elements, and in which: 
       FIG. 1  is a somewhat schematic perspective view of a leak sensor according to an exemplary embodiment of the present invention; 
       FIG. 2  is a somewhat schematic perspective view illustrating a leak sensor arranged on a pipe in accordance with another aspect of the present invention; and 
       FIG. 3  is a somewhat schematic block diagram illustrating a leak sensing system according to a still further aspect of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   The principles of the present invention will now be described more fully hereinafter with reference to various exemplary embodiments thereof. It should be recognized, however, that the invention may be embodied in many different forms and should therefore not be construed as being limited to any one or more of the embodiments set forth herein. Rather, the various embodiments are described herein so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those of ordinary skill in the art. 
     FIG. 1  is a somewhat schematic perspective view of a leak sensor  100  according to an exemplary embodiment of the present invention. Referring to  FIG. 1 , the leak sensor  100  preferably includes a film  110  that indicates whether a leakage has occurred. The film  110  is preferably a litmus paper that is further capable of indicating a constituent of a fluid such as, for example, a chemical used in a semiconductor apparatus. 
   Litmus is a reagent that is red in acid and blue in alkali. Litmus paper  110  is obtained by soaking a paper, such as a filter paper in litmus and then drying the paper. Since, by changing color, the litmus paper  110  enables users to visually determine whether a solution is acidic or alkali, it is a suitable film for indicating whether a chemical is leaked. If litmus paper  110  is adopted to indicate whether a chemical is leaked, the acidity may be visually checked and users may therefore be adequately prepared to cope with the acidity of the leaked chemical. As is known, the litmus paper  110  turns red in pH 5 or lower, blue in pH 8 or higher, and violet in pH 5-8. By observing a color change of the litmus paper  110 , the level of acidity of a leaked chemical can be visually checked and can thereby reduce the amount of time required for determining the kind of chemical leaked. 
     FIG. 2  is a somewhat schematic illustration of a leak sensor  100  arranged on a pipe  300 , in accordance with another aspect of the present invention. Referring to  FIGS. 1 and 2 , the litmus paper  110  is preferably wrapped around a circumference of a pipe  300  proximal to a connection. A length “L” of the litmus paper  110  is preferably sufficient to encircle the pipe  300  and is therefore dependent on the thickness of the pipe  300 . Furthermore, a width D of the litmus paper  110  should be sufficient to sense the occurrence of the leakage. In this embodiment, for example, the litmus paper  110  may have a width “D” of about 50 millimeters. 
   The width “D” of the litmus paper  110  is not limited thereto, however, and may be modified as desired according to any particular need or design. The litmus paper  110  preferably includes an adhesive for attaching the litmus paper  110  to the pipe  300 , such as a sticky layer arranged on a surface of the litmus paper  110 . 
   At least two wires  122 ,  123  are preferably encapsulated or otherwise incorporated into the litmus paper  110  in such a way as to be short-circuited by a leaked chemical when the leakage occurs. The wires  122 ,  123  should be spaced apart from each other at an appropriate distance “d” so as to be short-circuited when leakage occurs. If the space “d” between the wires  122 ,  123  is too large, the sensitivity of the leak sensor to a leakage occurrence may be lowered. On the other hand, if the space “d” is too small, the wires  122 ,  123  may be short-circuited due to reasons other than the occurrence of a leakage. The space “d” between the wires  122 ,  123  is preferably less than about 2 millimeters to increase the wires&#39; sensitivity to the occurrence of a leak. 
   The wires  122 ,  123  going from the sensor  100  to a connector  140  are preferably coated with a coating material  124 ,  125  to protect them from damage or accidental short-circuiting. In addition, the cables  124 ,  125  may be further enclosed in a cable coating  130  that is made of or coated with Teflon®. Teflon® is durable against chemicals, and can therefore protect the cables  124 ,  125  from damage due to the leaked chemicals. The leak sensor  100  of this embodiment is preferably short-circuited by a chemical leakage and should be replaced after a leakage occurs. The connector  140  is therefore preferably provided to enable ready replacement of the sensor  100  with a new one. The connector  140  is preferably electrically connected with a control box (or terminal) (see  500  of  FIG. 3 ) through a connector  410 . 
   Referring specifically to  FIG. 2 , the litmus paper  110  of the leak sensor  100  is preferably arranged near a connecting section of the pipe  300 . The pipe  300  may be any one of a number of different pipes providing a flow path for a fluid, such as chemicals, used in the manufacturing process. The pipe  300  may, for instance, be configured to supply or exhaust chemicals, or it may be a pipe configured for treating wastewater, such as acidic or alkaline wastewater. The connector  140  is preferably electrically connected to the control box  500  through an electrical connector  410  of a cable  400 . 
   When a leakage occurs in the pipe  300 , the litmus paper  110  preferably turns a specific color that depends on the content of the leaked chemical, thereby indicating a constituent of the chemical. In addition, the wires  122 ,  123  in the litmus paper  110  are short-circuited by the leaked chemical and transmit a signal to the control box  500  through the cables  130 ,  400 . Since, in this embodiment, a leak sensor  100  whose wires  122 ,  123  are short-circuited by a leaked chemical cannot be reused, the electrical connector  140  is disconnected from the control box electrical connector  410  and an electrical connector  140  from a new sensor  100  is attached. 
   In this embodiment, the leak sensor  100  may be able to sense even a small leakage because the litmus paper  110  is attached to a connection part of the pipe  300 . The leak sensor  100  thereby enables an operator to take remedial action in response to the leakage at an early stage to prevent damage resulting from the leakage. 
     FIG. 3  is a somewhat schematic block diagram illustrating a leak sensing system  200  according to a further aspect of the present invention. Referring to  FIG. 3 , a plurality of leak sensors  100 A,  100 B,  100 C,  100 D are attached to connection portions of a drain  600 . The drain could, for example, be a drain pipe  600  of a semiconductor apparatus. Each leak sensor  100 A,  100 B,  100 C,  100 D comprises litmus paper  110  and a plurality of wires  122 ,  123 . A cable  130 A,  130 B,  130 C,  130 D from each respective one of the leak sensors  100 A,  100 B,  100 C,  100 D is electrically connected to a control box or terminal  500 . The control box  500  preferably receives power of a predetermined voltage and includes a relay installed therein. The relay functions as a switch when leakage occurs. The wires  122 ,  123  receive an electric signal from the control box  500 . When the wires  122 ,  123  are short-circuited, a short-circuited electric signal (or leakage sensing signal) is transmitted back to the control box  500 . The control box  500  then preferably sends an alarm signal to the semiconductor apparatus in response to the short-circuited electric signal from the leak sensor  100 , thereby enabling an operator to repair the leak without delay. 
   The control box is also preferably provided with a plurality of lamps  510 ,  520 ,  530 ,  540  that illuminate in response to a short-circuited electric signal from a respective one of the leak sensors  100 A,  100 B,  100 C,  100 D. The lamps  510 ,  520 ,  530 ,  540  thereby visually indicate both when a leakage occurs and also the location of the leakage. For example, if a leakage sensing signal is transmitted to the signal box  500  from a leak sensor  100 B attached to a second connection portion of the drain pipe  600 , a second lamp  520  is preferably flickered to indicate that a leakage has occurred at the second connection portion. The other lamps  510 ,  530 ,  540  preferably operate in a similar manner with respect to the leak sensors  100 A,  100 C,  100 D arranged at the first, third, and fourth connection portions. The lamps  510 ,  520 ,  530 ,  540  may comprise light-emitting diodes (LEDs). The control box  500  is also preferably provided with a speaker  550  for emitting an audible alarm to inform an operator of a leakage sensed by one or more of the leak sensors  100 A,  100 B,  100 C,  100 D. 
   More specifically, when a leakage occurs at the second connector of the drain pipe  600 , the litmus paper  110  of the leak sensor  100 B changes color in response to the leaked chemical. The color preferably indicates a constituent of the leaked chemical. At the same time, the wires  122 ,  123  arranged in the litmus paper  110  of the leak sensor  100 B are short-circuited by the leaked chemical and transmit an electric signal indicating the leakage to the control box  500 . In response to the electrical signal, the second lamp  520 , corresponding to the leak sensor  100 B arranged at the second connector location, is flickered and an audible alarm is output from the speaker  550 . Using this system, the leak sensing system provides the user with the ability to identify and repair the leakage soon after it occurs. The visual and audible alarms generated by the control box  500  to indicate the leakage occurrence and location further permit an operator to quickly escape from an area in proximity to the place where the leakage occurs, thereby preventing inadvertent exposure to the leaked chemicals. 
   Although for convenience and simplicity  FIG. 3  illustrates only one drain pipe  600  having four connection portions connected with respective leak sensors  100 A,  100 B,  100 C,  100 D, any number of sensors may be supported. For instance, assuming a semiconductor cleaning apparatus is provided with ten drain pipes each having ten connectors, one hundred leak sensors can be attached to respective ones of the one hundred connectors to sense when and where a leakage occurs. 
   In summary, according to various principles and aspects of the present invention, numerous advantages can be achieved over the prior art. Among other things, the principles of the present invention help protect operators from accidents caused by chemical leaks. In addition, using the principles of the present invention, it is possible to prevent secondary and tertiary accidents resulting from damage to chemical pipes, electric cables, and other facilities caused by the leakage. Losses resulting from semiconductor manufacturing line down time can therefore be eliminated or reduced. A leak sensing system that utilizes litmus paper also makes it possible to reduce the time required for conducting environment safety patrols. More particularly, a leak sensing system constructed according to the principles of the present invention is advantageous in reducing the time for inspecting the semiconductor manufacturing lines following an earthquake. Furthermore, the principles of the present invention make it possible to achieve a more defect-free system that is capable of readily identifying leaks and preventing accidents. 
   Although the present invention has been described above in connection with various particular embodiments of the present invention as illustrated in the accompanying drawings, it should be noted that the invention is not limited to those embodiments. Rather, it will be apparent to those of ordinary skill in the art that various substitutions, modifications, and additions may be made thereto without departing from the spirit and scope of the invention as encompassed by the appended claims.