Abstract:
A vacuum apparatus includes a first isolation chamber, a second isolation chamber, a vacuum source configured to extract air from the first and second isolation chambers, and an isolation valve unit, wherein the isolation valve unit is configured to close a flow path between the vacuum source and the first isolation chamber before opening a flow path between the vacuum source and the second isolation chamber when the first isolation chamber is in a vacuum state and the second isolation chamber is at a pressure higher than that of the first isolation chamber.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to semiconductor device manufacturing equipment. More particularly, the present invention relates to semiconductor device manufacturing equipment including a vacuum apparatus and a method of operating the same. 
         [0003]    2. Description of the Related Art 
         [0004]    Generally, semiconductor devices may be fabricated by depositing one or more thin layers on a substrate, e.g., a semiconductor substrate, with the layers serving various functions. The layers may be patterned to form various circuit structures. In the fabrication of semiconductor devices, there may be many unit processes. For example, processes may include an impurity ion implantation process, e.g., for implanting impurity ions of group 3B, such as boron (B), or group 5B, such as phosphorus (P) or arsenic (As), into the semiconductor substrate. Other processes may include a thin layer deposition process for forming a material layer on the semiconductor substrate, an etching process for defining the material layer of the semiconductor substrate in a desired pattern, and a planarization process, e.g., chemical mechanical polishing (CMP), for planarizing an entire surface of the semiconductor substrate after depositing a layer, such as an interlayer insulating layer, etc. Still other process may include, e.g., a cleaning process for removing impurities from the wafer or a chamber, etc. 
         [0005]    Unit processes may be repeated several times to fabricate the semiconductor devices, and may be performed using various pieces of manufacturing equipment. In the semiconductor device manufacturing equipment, contaminants in air, particles such as polymers generated during fabrication processes, etc., may have a significant impact on reliability and yield of the semiconductor devices. Hence, semiconductor manufacturing equipment may be provided with a process chamber that is isolated from the outside, and which may be kept under a vacuum atmosphere in order to maintain the level of contaminants as low as possible. 
         [0006]    To pump the process chamber from an atmospheric pressure to a vacuum whenever a wafer is introduced into the process chamber, a long lead time may be required, which is undesirable. Accordingly, the semiconductor manufacturing equipment may include a load lock chamber in which a wafer cassette, in which a plurality of wafers to be introduced into the process chamber are mounted, is located and in which the level of vacuum is similar to that of the process chamber. The semiconductor manufacturing equipment may also include a transfer chamber provided with a robotic arm for taking a wafer out of the wafer cassette in the load lock chamber and transferring the wafer to the process chamber. In order to improve operation efficiency, the semiconductor manufacturing equipment having the process chamber, the load lock chamber, and the transfer chamber may be designed as a cluster, where one or more load lock chambers and process chambers are disposed around the transfer chamber, e.g., in a circular fashion. 
         [0007]    In order to improve the reliability and yield of semiconductor devices, it is important to maintain a high level of cleanliness inside the equipment, e.g., in the process chamber in which the semiconductor device manufacturing process is performed. To this end, the equipment may be pumped using a pumping apparatus such as a vacuum pump. In a cluster of semiconductor device manufacturing equipment, two neighboring load lock chambers may share one vacuum pump. The neighboring load lock chambers, and each of the load lock chambers and the vacuum pump, may be interconnected by an exhaust line, as illustrated in  FIG. 1 . 
         [0008]    Referring to  FIG. 1 , a load lock chamber A  10  and a load lock chamber B  12  may be provided with an exhaust line  14 . A purge gas supply  15  and a vacuum pump  16  may be connected to the load lock chambers A and B,  10  and  12 , via the exhaust line  14 , which may be arranged at front and rear ends, respectively, of the load lock chambers A and B,  10  and  12 . The front and rear ends of the load lock chambers A and B,  10  and  12 , may be provided with isolation valves for opening and closing the exhaust line  14 , e.g., isolation valves  18   a,    18   b,    18   c  and  18   d  located at the front end of load lock chamber A  10 , the rear end of load lock chamber A  10 , the front end of load lock chamber B  12 , and the rear end of load lock chamber B  12 , respectively. 
         [0009]    A purge gas, e.g. nitrogen (N 2 ), may be supplied from the purge gas supply  15  via the exhaust line  14  into the load lock chambers A and B,  10  and  12 . The load lock chambers A and B,  10  and  12  supplied with the purge gas may be pumped to a vacuum state by the vacuum pump  16 . The load lock chambers  10  and  12  may be selectively pumped and maintained at a predetermined pressure, i.e., vacuum, using the isolation valves  18   a,    18   b,    18   c,  and  18   d.    
         [0010]    In the exhaust structure illustrated in  FIG. 1 , a momentary eddy may be generated by mutual influence of the load lock chamber A  10  and the load lock chamber B  12 , whereby particles may be generated. For example, where the load lock chamber B  12  is to be pumped to a vacuum while the load lock chamber A  10  is maintained at a vacuum, the load lock chamber A  10  may be in a vacuum state while the load lock chamber B  12  is in an atmospheric pressure state, and the isolation valves  18   c  and  18   d  may be opened at the same time while the isolation valves  18   a  and  18   b  may be closed at the same time, such that only the load lock chamber B  12  is pumped by the vacuum pump  16  while the load lock chamber A  10  continues to maintain a vacuum. However, the opening of the isolation valve  18   d  and the closing of the isolation valve  18   b  may be mismatched in timing. That is, before the isolation valve  18   b  isolating the load lock chamber A  10  is fully locked, the load lock chamber B  12  may be pumped. When the isolation valve  18   d  is opened in the state in which the isolation valve  18   b  is not completely closed, an atmospheric pressure of air in the load lock chamber B  12  may flow into the load lock chamber A  10  via the exhaust line  14 . As a result, the pressure in the load lock chamber A  10  may increase rapidly, thereby generating an eddy such that particles are dispersed in the load lock chamber A  10 . 
         [0011]    If particles are generated in a load lock chamber, they may attach to a standby wafer that is waiting in the load lock chamber. Thus, the wafer may be contaminated and adverse effects may result, e.g., the semiconductor device may exhibit poor reliability, yield may be low, etc. Further, the particles may attach to the robotic arm used to withdraw the wafer from the load lock chamber. When the wafer is transferred by the robotic arm, the transfer chamber and the process chamber may be exposed to such contamination as well, which would necessitate performing a cleaning process on the load lock chamber, the transfer chamber, the process chamber, and the robotic arm. The need for cleaning may lead to a shortened preventive maintenance period of the whole semiconductor device manufacturing equipment, which may have a negative impact on productivity. 
       SUMMARY OF THE INVENTION 
       [0012]    The present invention is therefore directed to semiconductor device manufacturing equipment including a vacuum apparatus, and a method of operating the same, which substantially overcome one or more of the problems due to the limitations and disadvantages of the related art. 
         [0013]    It is therefore a feature of an embodiment of the present invention to provide a vacuum apparatus for semiconductor device manufacturing equipment that is configured to prevent placing a pressure chamber in flow communication with a relatively lower pressure chamber, and a method of operating the same. 
         [0014]    It is therefore another feature of an embodiment of the present invention to provide a vacuum apparatus for semiconductor device manufacturing equipment that is configured to isolate a pressure chamber before placing a relatively higher pressure chamber in flow communication with a shared exhaust line. 
         [0015]    At least one of the above and other features and advantages of the present invention may be realized by providing a vacuum apparatus including a first isolation chamber, a second isolation chamber, a vacuum source configured to extract air from the first and second isolation chambers, and an isolation valve unit, wherein the isolation valve unit is configured to close a flow path between the vacuum source and the first isolation chamber before opening a flow path between the vacuum source and the second isolation chamber when the first isolation chamber is in a vacuum state and the second isolation chamber is at a pressure higher than that of the first isolation chamber. 
         [0016]    The vacuum source may be connected to the first and second isolation chambers by exhaust lines, and the isolation valve unit may include isolation valves configured to open and close the exhaust lines, an isolation valve controller for controlling the opening and closing of the isolation valves, air supplies configured to supply air to the isolation valves according to an isolation valve opening signal from the isolation valve controller, and air dischargers configured to exhaust the air supplied to the isolation valves according to an isolation valve closing signal from the isolation valve controller. 
         [0017]    The isolation valves may include pneumatic regulators that are opened and closed by air from the air supplies, and vacuum regulators that are opened and closed according to whether the pneumatic regulators are opened and closed, respectively. The air supplies and the air dischargers may be connected to the pneumatic regulators via valves. The valves may be solenoid valves that are configured to alternately provide and block air from the air supplies to the pneumatic regulators. Signal lines may connect the isolation valve controller to the valves, and the valves may alternately provide and block air from the air supplies in correspondence with signals provided by the isolation valve controller. 
         [0018]    The vacuum apparatus may further include forced air dischargers configured to forcibly exhaust air existing between the isolation valves and the air supplies according to the isolation valve closing signal. The air supplies and the air dischargers may be connected to the pneumatic regulators via valves, and the forced air dischargers may be connected to the valves. Signal lines may connect the isolation valve controller to the pneumatic regulators. Signal lines may connect the isolation valve controller to the isolation valves, the air dischargers, and valves disposed between the air supplies and respective isolation valves. The isolation chambers may be load lock chambers. 
         [0019]    At least one of the above and other features and advantages of the present invention may further be realized by providing a method of operating a semiconductor device manufacturing equipment having a vacuum apparatus that includes a plurality of chambers having different pressure states, the method including closing a first exhaust line connected to a first chamber having a degree of vacuum higher than that of the other chambers among the plurality of chambers, and, after the closing of the first exhaust line, opening a second exhaust line connected to a second chamber having a pressure higher than that of the first chamber. 
         [0020]    The method may further include checking a closed state of the first exhaust line. The closing of the first exhaust line may include providing a close signal from an isolation valve controller to a first valve, the close signal causing the first valve to stop a supply of air from a first air supply to a first isolation valve so as to cause the first isolation valve to close the first exhaust line. The closing of the first exhaust line may further include forcibly exhausting air from the first valve using a first forced air discharger connected to the first valve. The opening of the second exhaust line may include supplying air from a second air supply to a second valve, and using the air from the second air supply to open the second valve between the second air supply and a second isolation valve so as to cause the second isolation valve to open the second exhaust line. 
         [0021]    At least one of the above and other features and advantages of the present invention may still further be realized by providing a method of operating a semiconductor device manufacturing equipment having a vacuum apparatus that includes a plurality of chambers having different pressure states, the method including simultaneously performing closing a first exhaust line connected to a first chamber having a degree of vacuum higher than that of the other chambers among a plurality of chambers, and opening a second exhaust line connected to a second chamber having a pressure higher than that of the first chamber. 
         [0022]    The closing of the first exhaust line connected to the first chamber may include stopping a supply of air from a first air supply to a first isolation valve, using a first forced air discharger to forcibly exhaust air inside a first valve provided between the first air supply and the first isolation valve, and closing the first valve to as to cause the first isolation valve to close the first exhaust line. The opening of the second exhaust line may include exhausting air existing between the first air supply and the first isolation valve, and using the exhausted air from the first air supply to open a second valve between a second air supply and a second isolation valve so as to cause the second isolation valve to open the second exhaust line. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which: 
           [0024]      FIG. 1  illustrates a schematic structure of an exhaust line for a pair of load lock chambers; 
           [0025]      FIG. 2  illustrates a cluster type of semiconductor device manufacturing equipment in accordance with an exemplary embodiment of the present invention; 
           [0026]      FIG. 3  illustrates a detailed structure of a load lock chamber of  FIG. 2 ; 
           [0027]      FIG. 4  illustrates a block diagram of an isolation valve unit according to an exemplary embodiment of the present invention; 
           [0028]      FIG. 5  illustrates a flowchart of a method of operating the isolation valve unit of  FIG. 4 ; 
           [0029]      FIG. 6  illustrates a block diagram of an isolation valve unit according to another exemplary embodiment of the present invention; and 
           [0030]      FIG. 7  illustrates a flowchart of a method of operating the isolation valve unit of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    Korean Patent Application No. 10-2006-0009541, filed on Feb. 1, 2006, and entitled: “Vacuum Apparatus of Semiconductor Device Manufacturing Equipment and Vacuum Method Using the Same,” is incorporated by reference herein in its entirety. 
         [0032]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are illustrated. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the figures, dimensions may be exaggerated for clarity of illustration. Like reference numerals refer to like elements throughout. 
         [0033]    As used herein, the term “air” is to be interpreted broadly, and is not limited to atmospheric air. In particular, the term “air” is used generically to describe a gas contained in chambers, connections, etc., of the semiconductor processing equipment described herein. The gas may be composed of a single component, e.g., nitrogen (N 2 ) or argon (Ar), mixtures thereof, atmospheric air, etc., and may be at pressures above or below atmospheric pressure, including high vacuum states of, e.g., 10 −6  Torr. 
         [0034]    With the rapid development of the information telecommunication field and the rapid popularization of information media such as computers, semiconductor devices are being rapidly developed. The semiconductor devices may be required to provide high-speed operation as well as to have mass storage capacity. Further, due to a tendency toward high-density integration and high capacity, each unit element forming a memory cell of a semiconductor device may be reduced in size. As the size of the unit element is reduced, a fabrication process margin may also be reduced. Accordingly, unit processes for fabricating the semiconductor device may require high precision. 
         [0035]    One such high precision process involves the use of plasma in order to precisely perform various unit processes such as a thin layer deposition process, an etching process and so on. A process chamber in which the process is substantially performed, a load lock chamber in which at least one wafer to be processed is on standby, and a transfer chamber in which the wafer is transferred may be required to maintain a constant level of pressure. Typically, the process chamber, the load lock chamber, and transfer chamber maintain the required pressure level using a vacuum pump. 
         [0036]    An embodiment of the present invention is directed to an isolation valve unit for controlling pressure, e.g., inside a load lock chamber of semiconductor device manufacturing equipment. The isolation valve unit may be adapted to be opened or closed with more rapidity than a conventional vacuum control system, so that an eddy may be prevented from being generated in the load lock chamber. This momentary eddy may be conventionally generated when relatively high pressure air is introduced into the load lock chamber. By preventing the eddy, a probability of generating particles in the load lock chamber can be reduced. Thus, conventional problems of the wafer that is on standby in the load lock chamber, such as wafer loss, the decrease of the preventative maintenance period etc., may be reduced or eliminated. 
         [0037]      FIG. 2  illustrates a cluster type of semiconductor device manufacturing equipment  100  to which an isolation value unit is applied in accordance with an exemplary embodiment of the present invention, and  FIG. 3  illustrates a detailed structure of a load lock chamber of  FIG. 2 . Referring to  FIG. 2 , a cluster type of semiconductor device manufacturing equipment  100  may include a plurality of process chambers  102  in which unit processes, such as a thin layer deposition process, an etching process etc., may be performed on at least one wafer W, an alignment chamber  104  for aligning a flat zone of the wafer W in one direction, a transfer chamber  108  in which a robotic arm  106  is provided for transferring the wafer W from the alignment chamber  104  to each of the process chambers  102 , and a plurality of load lock chambers  116 , each of which communicates with the transfer chamber  108  and is provided on one side thereof with a slit valve  110  opened when the robotic arm  106  enters therein, and provided on the other side thereof with a door  114  through which a wafer cassette  112 , in which the plurality of wafers W are mounted, enters. 
         [0038]    Referring to  FIG. 3 , each of the load lock chambers  116  may be provided on an upper portion thereof with a purge gas supply line  118  that is adapted to supply a purge gas, and on a lower portion thereof with an exhaust line  120  that is adapted to exhaust the purge gas supplied into each of the load lock chambers  116 . 
         [0039]    In the semiconductor device manufacturing equipment illustrated in  FIGS. 2 and 3 , each of the process chambers  102  may provide a hermetic space so that a unit process for manufacturing the semiconductor device can be performed. For example, various unit processes may be performed in the process chambers  102 , such as a thin layer deposition process of forming a predetermined thickness of thin film on the wafer W through a physical vapor deposition method and/or a chemical vapor deposition method, or an etching process of removing a surface of the wafer W exposed though a mask layer, such as a photoresist layer, which is formed on the wafer W, etc. Further, after an etching process is completed, an ashing process of oxidizing and removing the photoresist layer may be performed. Typically, the thin layer deposition process, the etching process, and the ashing process each increase uniformity and reliability by converting a reaction gas having excellent reactivity into a plasma state and causing the converted reaction gas to flow onto the wafer W. 
         [0040]    In each process chamber  102 , it may be very important to minimize the inflow of contaminants, such as particles, in order to generate uniform plasma. To this end, the process chambers  102  may be maintained in a vacuum state using a vacuum pump. For example, when the wafer W is loaded, each of the process chambers  102  may be pumped to a high vacuum, e.g., about 1×10 −6  Torr. Then, when supplied with a purge gas for inducing the plasma reaction, e.g., nitrogen (N 2 ), argon (Ar), etc., each of the process chambers  102  may be maintained in a low vacuum, e.g., between about 1×10 −3  Torr and about 1×10 −1  Torr. 
         [0041]    When the unit processes are completed in the process chambers  102  respectively, the slit valve  110  may be opened between each process chamber  102  and the transfer chamber  108  so that the robotic arm  106  can take the wafer W out of each process chamber  102 . At this time, a level of vacuum of each process chamber  102  is set to be higher than that of the transfer chamber  108 . Accordingly, air in the transfer chamber  108  is caused to flow into each process chamber  102 . As a result, air in each process chamber  102  is prevented from flowing toward the transfer chamber  108 , so that the contamination of the transfer chamber  108  may be reduced. 
         [0042]    Subsequently, when the wafer W withdrawn by the robotic arm  106  is to be transferred into any one of the load lock chambers  116 , the slit valve  110  between the load lock chamber  116  and the transfer chamber  108  may be opened. At this time, a degree of vacuum of the load lock chamber  116  may be set to be higher than that of the transfer chamber  108 , so that air in the load lock chamber  116  is prevented from flowing toward and contaminating the transfer chamber  108 . 
         [0043]    The wafer W may be on standby in the wafer cassette  112  until the other wafers W received in the wafer cassette  112  are sequentially transferred and the semiconductor device manufacturing process is complete. At this time, a strong acid solution or other diffusive substance remaining on the wafer W may evaporate and be dispersed in the form of fumes, which may attach to inner walls of the load lock chambers  116 . Such contaminants attached to the inner walls of the load lock chambers  116  can be later separated as loose particles, e.g., by an air stream or a momentary eddy in the load lock chambers  116 . The particles may attach to the surface of a wafer W that is on standby in the load lock chambers  116 , or a wafer W being transferred. As a result, a thin layer formed on the wafer W may be degraded or a subsequent process may fail. The particles in the load lock chambers  116  may be eliminated using the vacuum pump  122  connected via the exhaust line  120 . 
         [0044]    As described above, the purge gas supply line  118  supplied with the purge gas may be arranged on the upper portion of each of the load lock chambers  116 , and the exhaust line  120  for exhausting the purge gas supplied into each of the load lock chambers  116  may be arranged on the lower portion of each of the load lock chambers  116 . The doors  114  may be coupled to outer walls of the load lock chambers  116  respectively, and hermetically close the load lock chambers  116 . Each load lock chamber  116  may be pumped via the exhaust line  120  provided on the lower portion of the load-lock chamber  116 . For example, the load lock chambers  116  may be pumped to have a degree of vacuum of about 3×10 −3  Torr. In addition, the vacuum pump  122  may cooperate with a dry pump or a rotary pump capable of pumping the load lock chamber  166  to a pressure of about 1×10 −3  Torr. 
         [0045]    Although not shown, each load lock chamber  116  may be provided with a vacuum sensor, which may be inserted from the outside to the inside through a port formed on a side wall of the load lock chamber  116 . The vacuum sensor may sense the degree of vacuum of the load lock chamber  116 . For example, the vacuum sensor may include a Baratron® gauge for measuring a degree of vacuum in comparison to a reference pressure using a baffle, or a Pirani gauge for measuring a degree of vacuum using a principle that a thermal conductivity of gas is substantially proportional to a degree of vacuum, i.e., a pressure of residual gas, under a low pressure. 
         [0046]    The exhaust line  120  may be equipped with an isolation valve unit  124 , which may receive the measured signal output from the vacuum sensor and which may regulated a flow of the air pumped by the vacuum pump  122  so as to allow the degree of vacuum of the load lock chamber  116  to be set to a predetermined level. Vacuum sensors may be disposed in each load lock chamber  116 , at other suitable locations in the isolation valve unit  124  such as outputs of isolation valves, etc. The isolation valve unit  124  may control the vacuum state of the load lock chamber  116 . The isolation valve unit  124  may hold the exhaust line  120  closed until the door  114  of the load lock chamber  116  is closed, and may open the exhaust line  120  once the door  114  is closed and the load lock chamber  166  is sealed off, so as to enable the air in the load lock chamber  116  to be pumped by the vacuum pump  122 . 
         [0047]    In this manner, when the air in the load lock chamber  166  is pumped to a predetermined level and the load lock chamber  166  reaches a preset degree of vacuum, a purge gas supply (not shown) may supply the load lock chamber  166  with the purge gas ranging from several sccm (standard cubic centimeters per minute) to several tens of sccm via the purge gas supply line  118  provided on the upper portion of the load lock chamber  116 . The purge gas may cause particles, etc., in the load lock chamber  116  to be exhausted via the exhaust line  120 , thereby preventing the contamination of the load lock chamber  116 . 
         [0048]    Each load lock chamber  116  may serve as a buffering chamber for maintaining the degree of vacuum of each process chamber  102 , and may serve as a blockage area for preventing the process atmosphere of each process chamber  102  from being influenced by the outside. Thus, the purge gas may be supplied into the load lock chamber  116  via the purge gas supply line  118 , the purge gas may be diluted with fumes evaporated and dispersed from the surface of the wafer, and the diluted purge gas may be exhausted to the outside via the exhaust line  120  by the pumping of the vacuum pump  122 . The pumping of the vacuum pump  122  may enable contaminants such as particles to be eliminated from the load lock chamber  116 , as well as maintaining a pressure level required for the process. 
         [0049]    Conventionally, when the vacuum pump stops pumping the load lock chamber having a vacuum state, the isolation valve of the exhaust line connected between the load lock chamber and the vacuum pump is not rapidly closed. Hence, air flows into the load lock chamber having the vacuum state, so that a momentary eddy taken place. This eddy causes particles to be generated in the load lock chamber. 
         [0050]    In contrast, according to this embodiment of the present invention, the isolation valve unit  124  may be provided for the exhaust line connected between the load lock chamber  116  and the vacuum pump  122 . A structure of the isolation valve unit  124  according to an embodiment of the present invention will be described below in detail. 
         [0051]      FIG. 4  illustrates a block diagram of an isolation valve unit  124  according to an exemplary embodiment of the present invention, in which the isolation valve unit  124  may control the opening and closing of exhaust lines connected to two or more load lock chambers. Two load lock chambers  116   a  and  116   b  connected to the exhaust lines and the isolation valve unit  124  are illustrated in  FIG. 4 .  FIG. 5  illustrates a flowchart of a method of operating the isolation valve unit of  FIG. 4 . Operations illustrated in  FIG. 5  will be referenced parenthetically. 
         [0052]    Referring to  FIG. 4 , load lock chamber A  116   a  and load lock chamber B  116   b  may be connected to exhaust lines  120   a  and  120   b,  respectively. 
         [0053]    The exhaust lines  120   a  and  120   b  may be connected to the isolation valve unit  124 . The isolation valve unit  124  may include isolation valves  126   a  and  126   b  that are provided with vacuum regulators  128   a  and  128   b,  as well as well as pneumatic regulators  130   a  and  130   b,  for closing or opening the exhaust lines. The isolation valve unit  124  may further include valves  132   a  and  132   b  connected between the isolation valves  126   a  and  126   b  and the pneumatic tubes  134   a  and  134   b.  Additionally, the isolation valve unit  124  may include air supplies  136   a  and  136   b  and air dischargers  137   a  and  137   b  that are connected to the pneumatic tubes  134   a  and  134   b , as well as an isolation valve controller  138  that is connected to the pneumatic regulators  130   a  and  130   b , to the valves  132   a  and  132   b , and to the air dischargers  137   a  and  137   b.  The isolation valve controller  138  may also be connected to an equipment controller  140 . 
         [0054]    Rear ends of the vacuum regulators  128   a  and  128   b  may be connected to the vacuum pump  122 . The vacuum pump  122  may pump the load lock chambers  116   a  and  116   b  via exhaust lines  121   a  and  121   b.  The valves  132   a  and  132   b  may be connected to auxiliary components, e.g., joints or bends, etc. (not shown). In an implementation (not shown), the pneumatic tubes  134   a  and  134   b  may be directly connected to the pneumatic regulators  130   a  and  130   b  without the valves  132   a  and  132   b . The isolation valves  126   a  and  126   b  may be implemented as, e.g., solenoid valves. It will be appreciated, however, that this implementation is merely an example, and may be suitably modified by one of skill in the art. 
         [0055]    When the load lock chambers  116   a  and  116   b  are pumped, air supplied from the air supplies  136   a  and  136   b  reaches the pneumatic regulators  130   a  and  130   b  of the isolation valves  126   a  and  126   b  via the pneumatic tubes  134   a  and  134   b  and the valves  132   a  and  132   b . The pneumatic regulators  130   a  and  130   b  may be opened by the air, and thereby the vacuum regulators  128   a  and  128   b  may also be opened. As a result, the isolation valves  126   a  and  126   b  may be opened. In this state, in which the isolation valves  126   a  and  126   b  are opened, the load lock chambers  116   a  and  116   b  may be pumped by the vacuum pump  122 , thereby maintaining the load lock chambers  116   a  and  116   b  in a vacuum state. 
         [0056]    When the load lock chambers  116   a  and  116   b  are not pumped, the air supplies  136   a  and  136   b  may stop supplying the air, and then the air supplied to the pneumatic tubes  134   a  and  134   b  may be exhausted via the air dischargers  137   a  and  137   b.  Thus, the air flowing though the pneumatic regulators  130   a  and  130   b  and the vacuum regulators  128   a  and  128   b  may be stopped, and thus the isolation valves  126   a  and  126   b  may be closed. Thereby, the exhaust lines  121   a  and  121   b  between the load lock chambers  116   a  and  116   b  and the vacuum pump  122  may be closed, so that the load lock chambers  116   a  and  116   b  are not pumped. 
         [0057]    An exemplary process of operating the isolation valves  126   a  and  126   b  will now be described using a particular example of pumping the load lock chamber B  116   b  in the state where the load lock chamber A  116   a  maintains vacuum. Referring to  FIGS. 4 and 5 , a “load lock chamber B pumping” signal may be output from the equipment controller  140  to the isolation valve controller  138  (S 200 ). The isolation valve controller  138  receiving the “load lock chamber B pumping” signal may stop the supply of air by the air supply  136   a.  This may be accomplished by closing the valve  132   a  (S 202 ). 
         [0058]    At this point, a check may be performed to determine whether or not the isolation valve  126   a  connected to the valve  132   a  is closed (S 204 ). If the isolation valve  126   a  is not closed, the process may return to operation S 202 , and the state of the air supplied from the air supply  136   a  may be checked. 
         [0059]    Once the isolation valve  126   a  is closed, a signal may be given to supply air from the air supply  136   b  to the load lock chamber B  116   b.  Air supplied from the air supply  136   b  may be supplied to the valve  132   b  via the pneumatic tube  134   b . When the valve  132   b  is opened, the isolation valve  126   b  may also be opened (S 206 ). When the isolation valve  126   b  is opened, the vacuum pump  122  may be placed into flow communication with the load lock chamber B  116   b  via the exhaust lines  120   b  and  121   b . Thus, the load lock chamber B  116   b  may be pumped by the vacuum pump  122  (S 208 ). 
         [0060]    A check may be performed to determine whether or not the degree of vacuum inside the load lock chamber B  116   b  is within a required range (S 210 ). If the degree of vacuum inside the load lock chamber B  116   b  is not within the required range, pumping of the load lock chamber B  116   b  may be continued. 
         [0061]    After it is confirmed that the isolation valve  126   a  between the load lock chamber A  116   a  and the vacuum pump  122  is closed, the isolation valve  126   b  for pumping the load lock chamber B  116   b  may be opened. In other words, the closing of the isolation valve  126   a  connected to the load lock chamber A  116   a  may precede the opening of the isolation valve  126   b  connected to the load lock chamber B  116   b.  As a result, the external air of atmospheric pressure may be prevented from being introduced into the load lock chamber A  116   a  via the exhaust lines  120   a  and  121   a,  and thus it may be possible to prevent an eddy from being generated in the load lock chamber A  116   a.  By preventing the eddy, particles generated inside the load lock chamber A  116   a  may be kept to a minimum, thereby reducing or eliminating wafer loss, avoiding the decrease of the preventative maintenance period, etc. 
         [0062]    After it is confirmed that the closing of the isolation valve  126   a  is completed, the operation for opening the isolation valve  126   b  may be performed. Thus, atmospheric pressure may be prevented from being introduced into the load lock chamber A  116   a.    
         [0063]    In the embodiment just described, the opening of the isolation valve  126   b  may be delayed, which may extend an overall process time. This delay may be reduced or eliminated according to another exemplary embodiment of the present invention.  FIG. 6  illustrates a block diagram of an isolation valve unit  318  according to another exemplary embodiment of the present invention, and  FIG. 7  illustrates a flowchart of a method of operating the isolation valve unit of  FIG. 6 . Operations of the method illustrated in  FIG. 7  will be referred to parenthetically. Referring to  FIG. 6 , a load lock chamber A  300   a  and a load lock chamber B  300   b  may be connected to exhaust lines  302   a  and  302   b,  respectively. The exhaust lines  302   a  and  302   b  may be connected to the isolation valve unit  318 . 
         [0064]    The isolation valve unit  318  may include isolation valves  304   a  and  304   b  that close or open the exhaust lines. The isolation valve unit  318  may also include valves  306   a  and  306   b  between the isolation valves  304   a  and  304   b,  which control opening and closing of the isolation valves  304   a  and  304   b  using air supplied from air supplies  310   a  and  310   b.  The isolation valve unit  318  may further include forced air dischargers  308   a  and  308   b , and air dischargers  311   a  and  311   b,  which are connected to the valves  306   a  and  306   b.  An isolation valve controller  312  may be connected to the isolation valves  304   a  and  304   b,  to the air dischargers  311   a  and  311   b,  to the valves  306   a  and  306   b,  and to an equipment controller  314 . Rear ends of the isolation valves  304   a  and  304   b  may be connected to a vacuum pump  316  for pumping the load lock chambers  300   a  and  300   b  to a predetermined degree of vacuum via exhaust lines  303   a  and  303   b.    
         [0065]    The forced air dischargers  308   a  and  308   b  may help rapidly discharge air existing between the isolation valves  304   a  and  304   b  and the valves  306   a  and  306   b  once the supply of air from the air supplies  310   a  and  310   b  has been stopped. When the air existing between the isolation valves  304   a  and  304   b  and the valves  306   a  and  306   b  is forcibly discharged, an air discharge speed may be significantly increased as compared to the case in which the air is discharged without forcible discharge. The valves  306   a  and  306   b  may close rapidly and thus the isolation valves  304   a  and  304   b  may also be rapidly closed. As a result, atmospheric pressure air may be prevented from being introduced into the load lock chambers  300   a  and  300   b  while they are maintained in a vacuum state. 
         [0066]    The forced air dischargers  308   a  and  308   b  may be connected to the valves  306   a  and  306   b.  In another implementation, they may be connected to a section between the isolation valves  304   a  and  304   b  and the valves  306   a  and  306   b.    
         [0067]    In an implementation (not shown), the valves  306   a  and  306   b  may be omitted. Without the valves  306   a  and  306   b,  the forced air dischargers  308   a  and  308   b  may be directly connected to the rear ends of the isolation valves  304   a  and  304   b . The isolation valves  304   a  and  304   b  may be implemented as, for instance, solenoid valves. However, it will be appreciated that this construction is merely an example and may be suitably modified by one of skill in the art. 
         [0068]    When the load lock chambers  300   a  and  300   b  are pumped, air is supplied from the air supplies  310   a  and  310   b  when the valves  306   a  and  306   b  are open. The opening of the valves  306   a  and  306   b  causes the isolation valves  304   a  and  304   b  to open. When the isolation valves  304   a  and  304   b  are open, the load lock chambers  300   a  and  300   b  are pumped using the vacuum pump  316 , thereby maintained them in a vacuum state. In contrast, when the load lock chambers  300   a  and  300   b  are not pumped, the air supplies  310   a  and  310   b  stop supplying the air, and then the air is exhausted via the air dischargers  311   a  and  311   b.    
         [0069]    Air between the isolation valves  304   a  and  304   b  and the valves  306   a  and  306   b  is forced to be rapidly discharged through the forced air dischargers  308   a  and  308   b  connected to the valves  306   a  and  306   b,  so that the valves  306   a  and  306   b  may be closed more rapidly. By rapidly closing the valves  306   a  and  306   b,  the isolation valves  304   a  and  304   b  may also be closed more rapidly, and thus the air flowing between the load lock chambers  300   a  and  300   b  and the vacuum pump  316  via the exhaust lines  302   a,    303   a,    302   b,  and  303   b  may be interrupted. Thus, the load lock chambers  300   a  and  300   b  are not pumped. 
         [0070]    An embodiment of the present invention will now be described with reference to an exemplary operation of the isolation valves  304   a  and  304   b , wherein the load lock chamber B  300   b  is pumped while the load lock chamber A  300   a  maintains a predetermined degree of vacuum. Referring to  FIGS. 6 and 7 , a “load lock chamber B pumping” signal may be output from the equipment controller  314  to the isolation valve controller  312  (S 400 ). The isolation valve controller  312 , upon receiving the “load lock chamber B pumping” signal, may stop the supply of air from the air supply  310   a  (S 402 ). Stopping the supply of air from the air supply  310   a  may be accomplished by closing the valve  306   a.    
         [0071]    Air existing between the isolation valve  304   a  and the valve  306   a  may be rapidly discharged through the forced air discharger  308   a  so that the valve  306   a  may be rapidly (S 404 ). By connecting the forced air discharger  308   a  to the valve  306   a , the air existing between the isolation valve  304   a  and the valve  306   a  may be more rapidly exhausted than through natural exhaust. Thus, the valve  306   a  may be closed more rapidly, and the isolation valve  304   a  may also be closed more rapidly. 
         [0072]    A check may be performed to determine whether or not the isolation valve  304   a  is fully closed (S 406 ). If the isolation valve  304   a  is not closed, the process may return to operation S 402 , and the state of the air supplied by the air supply  310   a  to the side of the load lock chamber A  300   a  may be checked. 
         [0073]    Once the isolation valve  304   a  is closed, a signal may be given to supply the air from the air supply  310   b.  The air may be supplied from the air supply  310   b  via the valve  306   b.  When the valve  306   b  is opened, the isolation valve  304   b  may also be opened (S 408 ). As the isolation valve  304   b  is opened, the vacuum pump  316  is interconnected to the load lock chamber B  300   b  via the exhaust lines  302   b  and  303   b.  Thus, the load lock chamber B  300   b  may be pumped using the vacuum pump  316  (S 410 ). 
         [0074]    A check may be performed to determine whether or not the vacuum inside the load lock chamber B  300   b  is within a range required for the process (S 412 ). If the vacuum inside the load lock chamber B  300   b  is not within the required range, the pumping of the load lock chamber B  300   b  may be continued. 
         [0075]    According to another exemplary embodiment of the present invention, the isolation valve controller  312  receiving the “load lock chamber B pumping” signal may stop the supply of air from the air supply  310   a  and rapidly exhaust the air existing between the isolation valve  304   a  and the valve  306   b  through the forced air discharger  308   a  at the same time. In this embodiment, when the air existing between the isolation valve  304   a  and the valve  306   b  is exhausted through the forced air discharger  308   a,  two exhaust processes, a natural exhaust process forced exhaust process, may be performed. Thus, the closing speeds of the valve  306   a  and its cooperating isolation valve  304   a  may be significantly enhanced as compared to the natural exhaust process alone. 
         [0076]    As illustrated in  FIG. 7 , operations S 402  through S 410  may be sequentially performed. Even if operations S 402  through S 410  are sequentially performed, the valve  306   a  may be rapidly closed due to the forced air discharger  308   a.  Accordingly, it may be possible to reduce the time delay of opening the isolation valve  304   b  connected to the load lock chamber B  300   b.    
         [0077]    In another implementation, operations S 402  through S 410  may be performed at the same time. In particular, the “load lock chamber B pumping” signal output from the equipment controller  314  may be sent to the isolation valve controller  312 . The isolation valve controller  312  receiving the “load lock chamber B pumping” signal may stop the supply of air from the air supply  310   a,  and may simultaneously signal the air supply  310   b  to supply air. The supply of air through the valve  306   a  may be stopped, and simultaneously the remaining air existing between the isolation valve  304   a  and the valve  306   a  may be rapidly exhausted through the forced air discharger  308   a.  Thus, the valve  306   a  and its cooperating isolation valve  304   a  may be closed. 
         [0078]    In this configuration, the supply of air from the air supply  310   a  may be interrupted, while simultaneously air is supplied from the air supply  310   b.  As a result, the valve  306   a  and isolation valve  304   a  for the load lock chamber A  300   a  may be closed, while simultaneously the valve  306   b  and isolation valve  304   b  for the load lock chamber B  300   b  may be opened. 
         [0079]    In this manner, the isolation valve  304   a  may be adapted to be rapidly closed, so that it is possible to solve the conventional problem that the air existing in the exhaust lines  302   a  and  303   a  at an atmospheric pressure is introduced into the load lock chamber A  300   a  while it is in a vacuum state, which could generate an eddy. Further, the valve  306   a  and isolation valve  304   a  for the load lock chamber A  300   a  are adapted to be closed, and simultaneously the valve  306   b  and isolation valve  304   b  for the load lock chamber B  300   b  are adapted to be opened, so that a delay in time depending on the opening and closing between the isolation valves  304   a  and  304   b  can be reduced. 
         [0080]    As set forth above, in the present invention, the closing of the isolation valve for the load lock chamber that is in a vacuum state may precede the opening of the isolation valve for the load lock chamber that is in a non-vacuum state. Thus, it may be possible to prevent an eddy from being generated inside the load lock chamber of the vacuum state, thereby minimizing the particles generated inside the load lock chamber that is in the vacuum state. Thus, it may be possible to avoid conventional problems such as wafer loss, a decrease in the preventative maintenance period, etc., while improving the reliability and yield of the fabricated semiconductor devices. 
         [0081]    Forced air dischargers may be connected to valves that control the isolation valves, which may enable a more rapid closing the isolation valves. As a result, the delay in time depending on the opening and closing of the isolation valves can be reduced, and thus the efficiency of process may be enhanced. 
         [0082]    Exemplary embodiments of the present invention have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.