Patent Publication Number: US-2007095282-A1

Title: Apparatus for manufacturing semiconductor device with pump unit and method for cleaning the pump unit

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION  
      This application claims priority to Korean Patent Application No. 10-2005-0070324, filed on Aug. 01, 2005, the disclosure of which is herein incorporated by reference in its entirety.  
     BACKGROUND OF THE INVENTION  
      1. Technical Field  
      The present disclosure relates to an apparatus and method for manufacturing a semiconductor device and, more particularly, to an apparatus for manufacturing a semiconductor device with a pump unit and a method for cleaning the pump unit.  
      2. Discussion of Related Art  
      In general, semiconductor device fabrication involves three basic processes: deposition, photolithography, and etching. Deposition or etching equipment commonly includes a processing chamber defining a space in which wafers are loaded and processed. Processing chambers are designed to achieve and maintain a controlled environment such as by adjusting pressure within the processing chamber to a predetermined pressure. An exhaust system for exhausting reaction byproducts is provided in the chamber. Typically, the exhaust system includes an exhaust pipe connected to the chamber and pumps which are installed on the exhaust pipe. The commonly used types of pumps include a dry pump for adjusting the pressure within the chamber and a booster pump for enhancing pumping performance. If necessary, a turbo pump may be directly installed on the chamber to maintain a desired process vacuum level inside the chamber.  
      As the process steps are performed in the processing chamber, the reaction byproducts are deposited in the chamber and the pumps. The byproducts deposited in the chamber can begin to flake off resulting in particles that have a detrimental effect on wafer yield. The byproducts deposited in the pump increase resistance against the relative rotation between a rotor and stator of the pump, resulting in an increased mechanical load on the motor that reduces the compression performance of the pump. This reduction in the pump&#39;s compression performance can occur abruptly. In such case, the deposition process is not properly realized due to the pump malfunction.  
      Therefore, a need exists to periodically clean the chamber and the pumps. Generally, the pumps and chamber are cleaned simultaneously by supplying a reactive gas for cleaning the chamber and the pumps that are connected to the chamber. Alternatively, the pumps may be separated from the exhaust system and cleaned. In the case where the chamber and the pumps are cleaned simultaneously by the use of a reactive gas, since the pumps are cleaned by the same gas that has been used to clean the chamber, the cleaning efficiency with respect to the pumps is decreased. In the case where the pumps are separated from the exhaust system and cleaned, because separating and assembling the pumps is time-consuming, the length of the clean operation is increased. Increasing the length of the clean operation is undesirable because it adversely affects wafer throughput.  
     SUMMARY OF THE INVENTION  
      In an exemplary embodiment of the present invention an apparatus for manufacturing a semiconductor device includes a chamber and an exhaust system for exhausting byproducts from the chamber and adjusting an internal pressure of the chamber. The exhaust system includes an exhaust pipe connected to the chamber, a pump unit coupled with the exhaust pipe, and a cleaning unit connected to a portion of the exhaust pipe or directly connected to the pump unit to supply a cleaning gas to the pump unit.  
      In an exemplary embodiment of the present invention, the pump unit includes an inlet and an outlet connecting the pump unit to the exhaust pipe, a dry pump for adjusting the internal pressure of the chamber, and a booster pump installed between the inlet and the dry pump for enhancing a pumping performance of the dry pump.  
      In an exemplary embodiment of the present invention, the cleaning unit includes a gas supply pipe for supplying the cleaning gas, an activation member for activating the cleaning gas, and an injection pipe for injecting the cleaning gas activated by the activation member into the pump unit.  
      The activation member may include a plasma generator generating plasma from the cleaning gas. The plasma generator may include a casing arranged between the injection pipe and the cleaning gas supply pipe, a first electrode provided on a first surface of the casing, a second electrode provided on a second surface of the casing arranged facing the first surface, and a power source for supplying power to the first or second electrode.  
      The activation member may include a heater for heating the cleaning gas.  
      In an exemplary embodiment of the present invention, the cleaning gas includes an etching gas for etching the byproducts deposited in the pump unit and an auxiliary gas chemically bonding to a first component of the etching gas, which is not directly related to the etching, to prevent a second component of the etching gas, which is directly related to the etching, from reacting with the first component.  
      In an exemplary embodiment of the present invention, the cleaning gas supply pipe includes an etching gas supply pipe for supplying the etching gas to the activation member and an auxiliary gas supply pipe for supplying the auxiliary gas to the activation.  
      In an exemplary embodiment of the present invention, the cleaning unit includes a first flow adjusting unit installed on the etching gas supply pipe, a second flow adjusting unit installed on the auxiliary gas supply pipe, and a flow control unit for controlling the first and second flow adjusting units. A mixture rate of the etching gas and the auxiliary gas can be adjusted by the first and second flow adjusting units.  
      In an exemplary embodiment of the present invention, the injection pipe is inserted into a pipe provided in the pump unit and an outlet of the injection pipe is designed to dispense the cleaning gas in a direction that is substantially identical to a direction in which a gas flows in the exhaust system. Preferably, the outlet of the injection pipe is designed to dispense the cleaning gas in a direction that is substantially parallel to the direction in which the gas flows in the exhaust system.  
      In an exemplary embodiment of the present invention, the injection pipe includes a showerhead installed on the outlet, the showerhead being provided with a plurality of dispensing holes for widely dispensing the cleaning gas.  
      In an exemplary embodiment of the present invention, the cleaning unit is connected to the inlet of the pump unit or to a pipe connecting the inlet to the booster pump. The cleaning unit may be connected to a pipe connecting the booster pump to the dry pump. The dry pump may include a plurality of stages and the cleaning unit may be connected to one of pipes connecting the stages. The cleaning unit may be connected to a pipe connecting the dry pump to the outlet.  
      In an exemplary embodiment of the present invention, the exhaust system further includes a load measuring unit for measuring a load of the motor provided in the pump unit and a main controller controlling a cleaning timing of the pump unit according to a measured value transmitted from the load measuring unit.  
      In an exemplary embodiment of the present invention, a method of cleaning a pump unit connected to an exhaust pipe for exhausting reacting byproducts out of a chamber used in semiconductor device manufacturing includes: connecting a cleaning gas supply pipe to a portion of the exhaust pipe or to the pump unit directly; and supplying the cleaning gas to the pump unit through the cleaning gas supply pipe. The cleaning gas may be directly supplied to a region where a relatively large amount of the reaction byproducts are deposited in the pump unit.  
      In an exemplary embodiment of the present invention, the cleaning of the pump unit is performed while the process is being performed in the chamber. The cleaning of the pump unit may be performed when a predetermined number of processes for processing the wafers are performed in the chamber or a predetermined time has lapsed. The cleaning of the pump unit may be performed by continuously supplying the cleaning gas into the pump unit at a predetermined time interval regardless of a progress of the process. The cleaning of the pump unit may be performed only when the chamber is being cleaned. The cleaning of the pump unit may be performed only when there is an error after a self-diagnosis is performed for the pump unit. A current flowing in a motor of the pump unit may be continuously measured and the cleaning of the pump unit may be performed when a measured value of the current is outside a preset range. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will become readily apparent to those of ordinary skill in the art when descriptions of exemplary embodiments thereof are read with reference to accompanying drawings.  
       FIG. 1  is a schematic view of an apparatus for manufacturing a semiconductor device according to an exemplary embodiment of the present invention.  
       FIG. 2  is a view of the exhaust system of  FIG. 1 , according to an exemplary embodiment of the present invention.  
       FIG. 3  is a view of the activation member of  FIG. 2 , according to an exemplary embodiment of the present invention.  
       FIG. 4  is a view of the activation member of  FIG. 2 , according to an exemplary embodiment of the present invention.  
       FIG. 5  is a view of an injection pipe inserted in a distribution pipe according to an exemplary embodiment of the present invention.  
       FIG. 6  is a view of an injection pipe inserted in a distribution pipe according to an exemplary embodiment of the present invention.  
       FIGS. 7A through 7E  are views illustrating a variety of locations of the distribution pipes coupled to a pump unit according to exemplary embodiments of the present invention.  
       FIG. 8  is a schematic view of the exhaust system of  FIG. 1 , according to an exemplary embodiment of the present invention. 
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS  
      Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity.  
       FIG. 1  is a schematic view of an apparatus for manufacturing a semiconductor device according to an exemplary embodiment of the present invention. Referring to  FIG. 1 , a semiconductor device manufacturing apparatus  1  includes a chamber  10  and an exhaust system  20 . The chamber  10  is configured with a substrate support for supporting a semiconductor substrate such as a wafer (not shown). A process gas that will be deposited on the wafer is supplied into the chamber  10  through a gas supply pipe  12 . The exhaust system  20  is coupled with the chamber  10 . The exhaust system  20  is operable to maintain an internal pressure of the chamber  10  at a process pressure and exhaust reaction byproducts out of the chamber  10 .  
      The exhaust system  20  of  FIG. 1  includes an exhaust pipe  100 , a pump unit  200  and a cleaning unit  300 . The exhaust pipe  100  is connected to the chamber  10  to function as a conduit through which a gas exhausted from the chamber  10  flows. The pump unit  200  is installed on the exhaust pipe  100  to forcedly remove the gas from the chamber  10  by suction and maintain the internal pressure of the chamber at the process pressure. The cleaning unit  300  is connected to the pump unit  200 . The cleaning unit  300  supplies a cleaning gas into the pump unit  200  to remove the reaction byproducts deposited in the pump unit  200 . In an exemplary embodiment of the present invention, the cleaning unit  33  is directly connected to the pump unit  200  to directly supply the cleaning gas to the pump unit  200 .  
       FIG. 2  shows a view of the exhaust system  20  of  FIG. 1 , according to an exemplary embodiment of the present invention. Referring to  FIG. 2 , the pump unit  200  includes an inlet  282 , an outlet  284 , a booster pump  220 , and a dry pump  240 . The pump unit  200  is connected to the exhaust pipe  120  through the inlet  282  and to the exhaust pipe  140  through the outlet  284 . The reaction byproducts exhausted from the chamber  10  are directed into the pump unit  200  via the inlet  282  and exhausted out of the pump unit  200  through the outlet  284 . The dry pump  240  is operable to maintain the internal pressure of the chamber  10  at the process pressure, and the booster pump  220  is operable to enhance the pumping performance of the dry pump  240 .  
      The dry pump  240  may be arranged between the inlet  282  and the outlet  284 , and the booster pump  220  may be arranged between the inlet  282  and the dry pump  240 . As shown in  FIG. 2 , the inlet  282 , the booster pump  220 , the dry pump  240 , and the outlet  284  are connected by the pipes  262 ,  264  and  268  therebetween. To maintain the internal pressure at a predetermined level, the dry pump  240  includes a plurality of stages  242  that compress air. The stages  242  are connected to each other, for example, by a pipe  266 . The number and type of the stages  242  may vary according to the process pressure of the chamber  10 .  
      Although not shown as such in  FIG. 2 , the pump unit  200  may include only the dry pump  240 . It is to be understood that various types of dry pump  240  are suitable. For example, the dry pump  240  may include only one stage  242  or a plurality of stages  242 , or a screw-shaped compressor instead of the stages.  
      As the process is performed, the reaction byproducts are deposited in the pump unit  200 . The reaction byproducts may be deposited in the pipes  262 ,  264 ,  266 , and/or  268  and/or in the pump  220  and/or in the pump  240 . When a sufficient amount of the reaction byproducts are deposited in the pump unit  200 , the pump performance is degraded, as a result of which the internal pressure of the chamber  10  may not be maintained at the desired process pressure.  
      The cleaning unit  300  is provided to clean the pump unit  200 . Although not shown as such in  FIG. 1 , the cleaning unit  300  may be connected to the exhaust pipe  120 , for example, near the pump unit  200  to supply the cleaning gas to the pump unit  200 . The cleaning unit  300  may be directly connected to the pump unit  200 , as shown in  FIG. 1 , to supply the cleaning gas into the pump unit  200 .  
      Referring to  FIG. 2 , the cleaning unit  300  includes a cleaning gas supply pipe  320 , an injection pipe  340  and an activation member  360 . The cleaning gas may be supplied from a cleaning gas storage unit (not shown) to the pump unit  200  via the gas supply pipe  320 . The activation member  360  is installed on the cleaning gas supply pipe  320  to activate the cleaning gas. The injection pipe  340  is directly connected into the pump unit  200  to supply the activation gas to the pump unit  200 .  
      The cleaning gas may include an etching gas and an auxiliary gas. The etching gas serves to etch the reaction byproducts deposited in the pump unit  200 . In an exemplary embodiment of the present invention, the etching gas includes a first and second component, wherein the first component is not directly related to the cleaning and the second component is directly related to the cleaning. Before the second component of the etching gas that is directly related to the cleaning is chemically bonded to the reaction byproducts in the pump unit  200 , the reaction byproducts may bond to the first component of the etching gas that is not directly related to the cleaning. This reduces cleaning efficiency. In accordance with an exemplary embodiment of the present invention, an auxiliary gas is provided that includes a component that can easily chemically bond to the first component of the etching gas.  
      For example, when a material to be deposited on the wafer is tungsten, NF 3  is used as the etching gas and O 2  is used as the-auxiliary gas. In the NF 3 , a component that is directly related to the etching is F 2  that reacts with the tungsten to generate WF x , and a component that is not directly related to the etching is the N that bonds to the O 2  to form N 2 O. In the pump unit  200 , according to an exemplary embodiment of the present invention, the N bonds to the O 2 , and the N 2  is prevented from bonding to the F.  
      Perfluoro carbon, ClF 3 , or F 2  may be used as the etching gas and N 2  may be used as the auxiliary gas. It is to be understood that various combinations of etching gas and auxiliary gas are suitable for implementing the present invention.  
      As shown in  FIG. 2 , the cleaning gas supply pipe  320  includes an etching gas supply pipe  322  and an auxiliary gas supply pipe  324 . The etching gas and the auxiliary gas may be mixed with each other and then supplied into the pump unit  200 . The etching gas supply pipe  322  and the auxiliary gas supply pipe  324  are connected to the activation member  360 , and the gases can be mixed in the activation member  360 . A separated mixer (not shown) for mixing the etching gas with the auxiliary gas may be provided. Alternatively, the etching gas and the auxiliary gas may be separately supplied to the pump unit  200 .  
      To adjust a mixing ratio of the etching gas and the auxiliary gas, flow adjusting units  322   a  and  324   a  may be installed on the etching gas supply pipe  322  and the auxiliary gas supply pipe  324 , respectively. For example, a mass flowmeter or a flow control valve may be used as the flow adjusting units  322   a  and  324   a . Regulators  322   b  and  324   b  may be installed on the etching gas supply pipe  322  and the auxiliary gas supply pipe  324 , respectively. The flow adjusting units  322   a  and  324   a  are controlled by a flow control unit  326 . The mixing ratio of the etching gas and the auxiliary gas can be adjusted by manipulating the flow control unit  326 .  
      The injection pipe  340  is directly connected to the pump unit  200  to supply the cleaning gas into the pump unit  200 . A valve  340 a for selectively closing the passage of the injection pipe  340  is installed on the injection pipe  340 . For example, the valve  340   a  may comprise a solenoid valve that can be electrically controlled. The valve  340   a  is controlled by the flow control unit  326 .  
      The cleaning gas may be supplied into the pump unit  200  in a state where it is activated.  
       FIG. 3  is a view of the activation member  360  of  FIG. 2 , according to an exemplary embodiment of the present invention. Referring to  FIG. 3 , the activation member  360  comprises a plasma generator  360   a  activating the cleaning gas to a plasma state. The plasma generator  360   a  includes a casing  362 , a first electrode  364 , a second electrode  366 , and a power source  368 . The etching gas supply pipe  322  and the auxiliary gas supply pipe  324  are connected to a first face of the casing  362 . The injection pipe  340  is connected to a second face of the casing  362 . The first electrode  364  is installed on a first side surface of the casing  362  and the second electrode  366  is installed on a second side surface of the casing  362  arranged facing the first side surface. The power source  368  applies a voltage, such as a high voltage, to the first electrode  364 . The second electrode  366  may be grounded. A radio frequency generator for applying a radio frequency may be used as the power source  368 . The radio frequency applied from the radio frequency generator is controlled by a power control unit  369 .  
       FIG. 4  is a view of the activation member  360  of  FIG. 2 , according to an exemplary embodiment of the present invention. As shown in  FIG. 4 , the activation member  360  may include a heater  360   b  activating the cleaning gas to an ion state. The heater  360   b  includes a casing  362 ′, a heat wire  364 ′, and a power source  368 ′. The etching gas supply pipe  322  and the auxiliary gas supply pipe  324  are connected to a first surface of the casing  362 ′ and the injection pipe  340  is connected to a second surface of the casing  362 ′. The heat wire  364 ′ is installed on an outer circumference of the casing  362 ′. That is, the heat wire  364 ′ is wound around the casing  362 ′ and supplied with power from the power source  368 ′. The power source  368 ′ is controlled by a power control unit  369 ′.  
      The etching gas and the auxiliary gas flow into the casing  362  of the activation member  360  through the etching gas supply pipe  322  and the auxiliary gas supply tube  324 , after which they are mixed in the casing  362  and activated to a radical or ion state. Then, the mixture gas in the radical or ion state is directly supplied into the pump unit  200 .  
       FIG. 5  is a view of an injection pipe  340  inserted in a distribution pipe according to an exemplary embodiment of the present invention. The injection pipe  340  is connected to the activation member  360 . The injection pipe  340  penetrates the pipe  262  ( 264 ,  266  or  268 ) of the pump unit  200  such that an outlet thereof is disposed in the pipe  262  ( 264 ,  266  or  268 ). The outlet of the injection pipe  340  is designed to dispense the cleaning gas in a first direction, as indicated by the dotted arrow in  FIG. 5 , which is substantially identical to a second direction, as indicated by the solid arrow in  FIG. 5 , in which the gas flows through the pipes  262 ,  264 ,  266 , and  268 . According to an exemplary embodiment of the present invention, the cleaning gas supplied through the cleaning unit  300  can be stably supplied to a desired region while flowing through the pipes  262 ,  264 ,  266 , and  268  in the direction in which the gas flows. Here, the gas flowing through the pipes  262 ,  264 ,  266 , and  268  is gas exhausted from the chamber  10 . In an exemplary embodiment of the present invention, the first direction is substantially identical to the second direction means that an angle θ between the gas flow direction and the cleaning gas dispensing direction is as follows: 0°≦θ≦90°.  
      For example, the injection pipe  340  includes an insertion portion  342  substantially perpendicularly inserted into the pipe  262  ( 264 ,  266  or  268 ) and a dispensing portion  344  extending from an end of the insertion  242  in the first direction. The insertion and dispensing portions  342  and  344  may be identical in diameter. In an exemplary embodiment of the present invention, the outlet of the injection pipe  340  is designed to dispense the cleaning gas in a direction that is substantially parallel to the gas flow direction in the pipe  262  ( 264 ,  266  or  268 ).  
       FIG. 6  shows a view of the injection pipe  340  according to an exemplary embodiment of the present invention. Referring to  FIG. 6 , the injection pipe  340  is designed to widely dispense the cleaning gas. The injection pipe  340  includes an insertion portion  342 , a dispense portion  344  and a showerhead  346 . Since the insertion portion  342  and the dispensing portion  344  are basically identical to those of  FIG. 5 , further description thereof will be omitted in the interests of simplicity and clarity. The showerhead  346  uniformly dispenses the cleaning gas in a relatively wide range. The showerhead  346  is coupled to an end of the dispensing portion  344 . The shower head  346  includes a side wall  346   a  and a spraying plate  346   b  that define a space in which the cleaning gas exhausted from the dispensing portion  344  temporarily stays before it is supplied into the pipe  262  ( 264 ,  266  or  268 ). The spraying plate  246   b  is provided with a plurality of spraying holes  346   c  through which the cleaning gas introduced into the space is widely dispensed into the pipe  262  ( 264 ,  266  or  268 ).  
      The injection pipe  240  may be connected to various locations of the pump unit  200 . For example, as shown in  FIG. 2 , the injection pipe  340  may be connected to the pipe  262  interconnecting the inlet  282  and the booster pump  220 . As shown in  FIG. 7A , the injection pipe  240  may be connected to the pipe  264  connecting the booster pump  220  to the dry pump  240 . As shown in  FIG. 7B , the injection pump  340  may be connected to the pipe  266  connecting the stages  242  arranged in the dry pump  240 . As shown in  FIG. 7C , the injection pump  340  may be connected to the pipe  268  connecting the outlet  284  to the dry pump  240 . As shown in  FIG. 7D , the injection pump  340  may be directly connected to the booster pump  220 . As shown in  FIG. 7E , the injection pump  340  may be coupled to a portion of the exhaust pipe  120  near the pump unit  20 .  
      Because the internal pressure of the exhaust pipe  140  connected to the outlet  284  of the pump unit  200  shown in  FIG. 2  is higher than that of the exhaust pipe  120  connected to the inlet  282 , the amount of reaction byproducts deposited in the exhaust pipe  140  may be greater than that of the reaction byproducts deposited in the exhaust pipe  120 . When the injection pipe  340  is directly connected to the outlet  284  or to the pipe  268  connecting the dry pump  240  to the outlet  284  in accordance to an exemplary embodiment of the present invention, the cleaning efficiency with respect to the pump unit  200  and the exhaust pipe  100  connected to the outlet  284  can be improved.  
      The connection location of the injection pipe  340  to the pump unit  200  may be set at a location where a relatively large amount of byproducts are deposited in the pump unit  200 . For example, when the relatively large amount of the byproducts are deposited in the booster pump  220  of the pump unit  200 , as shown in  FIG. 2 , the injection pipe  340  may be connected to the pipe  262  connecting the inlet  282  to the booster pump  220  or directly connected to the booster pump  220 .  
      Although not shown as such in  FIGS. 2 and 7 A through  7 E, a plurality of injection pipes  340  may be installed on different locations of the exhaust pipe  120 , for example, near the pump unit  200 , or directly connected to the pump unit  200 .  
      The flow control unit  326  and the power control unit  369  are controlled by a main control unit  400  controlling an overall operation of the apparatus. The main control unit  400  controls the cleaning timing of the pump unit  200  by controlling the flow control unit  326  and the power control unit  369 .  
      The cleaning of the pump unit  200  may be periodically performed. For example, when a predetermined number of processes for processing wafers is performed in the chamber  10  or a predetermined time elapses, the main controller  400  controls the flow control unit  326  and the power control unit  369  to clean the pump unit.  
      The cleaning of the pump unit  200  may be continuously performed. For example, when the process is being performed in the chamber  10 , the main control unit  400  controls the flow control unit  326  and the power control unit  369  such that the cleaning gas can be continuously supplied into the pump unit  20  at a predetermined time interval regardless of the current processing stage.  
      The cleaning of the pump unit  200  may be performed with the cleaning of the chamber  10 . For example, the main control unit  400  controls the flow control unit  326  and the power control unit  369  such that the cleaning of the pump unit  200  can be realized when the chamber  10  is cleaned.  
      The cleaning of the pump unit  200  may be performed by the manipulation of a worker periodically or aperiodically. The worker may manipulate the main control unit  400  directly or remotely.  
      The pump unit  200  may be cleaned depending on when the apparatus operates or on the production circumstances. For example, the main control unit  400  controls the flow control unit  326  and the power control unit  369  such that the pump unit  200  can be cleaned at a predetermined point in time when the apparatus is not operated.  
      The pump unit  200  may be cleaned through a self-diagnosis method. For example, when the process is being performed and a load out of a range preset in a motor (not shown) provided on the pump unit  200  is applied, the main control unit  400  controls the flow control unit  326  and the power control unit  369  to clean the pump unit  200 . For example, as shown in  FIG. 8 , measuring units  380  are included for measuring currents flowing in the motors provided on the booster pump  220  and the stages  242 . The measuring units  380  transmit measured values to the main control unit  400 . When the measured values fall out of the preset range, the main control unit  400  controls the flow control unit  326  and the power control unit  369  to clean the pump unit  200 .  
      According to an exemplary embodiment of the present invention, the pump unit is cleaned by directly supplying the cleaning gas to the pump unit, and the cleaning efficiency is improved as compared with the case where the pump unit is cleaned by the same cleaning gas used to clean the chamber.  
      In an exemplary embodiment of the present invention, the pump unit can be cleaned in a state where the pump unit is connected to the exhaust pipe, and because there is no need to separate the pump unit from the exhaust pipe, equipment operating time can be increased and cleaning can be easily performed.  
      According to an exemplary embodiment of the present invention, when the pump is operating as the process is being performed in the chamber, the pump unit can be cleaned and the equipment operation rate may be improved.  
      According to an exemplary embodiment of the present invention, an etching gas and an auxiliary gas are used as the cleaning gas, and the components of the etching gas that are activated to a radical or ion state may not bond to each other in the pump unit.  
      Furthermore, since the pump unit can be cleaned periodically or at an appropriate point in time, the pump unit can be maintained at or restored to its initial state. Therefore, the service life of the pump unit increases and a reduction in the equipment operating time due to a malfunction of the pump unit can be minimized or prevented.  
      Although exemplary embodiments of the present invention have been described in detail with reference to the accompanying drawings for the purpose of illustration, it is to be understood that the inventive processes and apparatus should not be construed as limited thereby. It will be readily apparent to those of reasonable skill in the art that various modifications to the foregoing exemplary embodiments can be made without departing from the scope of the invention as defined by the appended claims, with equivalents of the claims to be included therein.