Abstract:
An exhaust gas treatment system treats exhaust gases collected from at least one PFC dealing device that deals with a PFC gas. The exhaust gas treatment system includes: an exhaust emission line through which the exhaust gases collected from the PFC dealing device; an external exhaust gas disposal device connected to the exhaust emission line so as to purify the exhaust gases for exhaust emission; a gas treatment device for eliminating the PFC gas from the exhaust gases; a gas treatment line branched from the exhaust emission line to supply the exhaust gases to the gas treatment device; and an intermediate line for discharge the treated exhaust gases from the gas treatment device to the external exhaust gas disposal device.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a gas treatment method and gas treatment system such as gas recovery etc. used in semiconductor manufacturing processes, which performs treatment for an exhaust gas expelled from a PFC gas dealing device in which a PFC gas is used such as an etching device and the like in an etching treatment step which are used in semiconductor manufacturing semiconductor manufacturing equipment. 
         [0003]    2. Description of the Related Art 
         [0004]    Some gases such as fluorine compounds and the like used in an etching step and the like in the semiconductor manufacturing processes is influencing on Greenhouse effect, and such gases hardly decompose for a long time and stable for an extremely long time and they have a very higher global warming effect than that of carbon dioxide. There are CF 4 , C 2 F 6 , C 3 F 8 , C 2 F 4 , CHF 3 , C 4 F 8 , NF 3  and the like as Greenhouse effect gases. Generally, they are so-called as PFC (Per Fluoro Compound) gases having extremely high global warming coefficients. The PFC gases are used in the semiconductor manufacturing processes at a much smaller mass level in comparison with the usage of CO 2 , but there is anxiety about accumulation of PFC emission in the air. 
         [0005]    Greenhouse effect gases (e.g., PFC gases) are emitted together with exhaust gas in the air though not only the conventional etching step but also processing steps such as CVD (chemical vapor deposition) and the like in the manufacturing processes for semiconductor devices, liquid crystal devices and the like. Thus there is a problem of promotion of global warming. 
         [0006]    Therefore there have been considered how to cope with reduction of the PFC gases in the semiconductor manufacturing processes. For example, there are some attempts: to optimize those processes to reduce the usage mass of PFC gases with a improved treatment method; to recover and reuse the PFC gases; to develop a treatment method to use an alternative gas; to develop another treatment method to decompose and detoxify the gases; and to develop a PFC gases recovery device (See Japanese Patent Application Publication No. 2005-188717). 
       SUMMARY OF THE INVENTION 
       [0007]    Generally, as shown in  FIG. 1 , a conventional exhaust gas treatment system uses suction pumps for exhaust gas of post-etching  11  attached to etching devices respectively in semiconductor manufacturing equipment. The exhaust gases are expelled from the suction pumps  11  after etching to pass through the exhaust emission line  5  of exhaust emission system towards a gas recovery device, a dry or wet type detoxification device or the like, and they are treated by the external exhaust gas disposal device  4 , after that, they are expelled to the outside. 
         [0008]    However, with such conventional processing steps, there is a problem insufficient to prevent from emission of Greenhouse effect gases (i.e. , PFC gases) for promoting global warming in the air. 
         [0009]    Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an exhaust gas treatment system and method capable of easily and sufficiently preventing from the PFC gases expelled from not only the conventional etching step but also processing steps such as CVD and the like in the manufacturing processes for semiconductor devices, liquid crystal devices and the like, using a pertinent device or recovery device and the like placed at the upstream near the PFC gas dealing device. 
         [0010]    According to the present invention, there is provided an exhaust gas treatment system for treating exhaust gases collected from at least one PFC dealing device which deals with a PFC gas, the system comprising: 
         [0011]    an exhaust emission line through which the exhaust gases collected from the PFC dealing device; 
         [0012]    an external exhaust gas disposal device connected to the exhaust emission line so as to purify the exhaust gases for exhaust emission; 
         [0013]    a gas treatment device for eliminating the PFC gas from the exhaust gases; 
         [0014]    a gas treatment line branched from the exhaust emission line to supply the exhaust gases to the gas treatment device; and 
         [0015]    an intermediate line for discharge the treated exhaust gases from the gas treatment device to the external exhaust gas disposal device. 
         [0016]    Also, according to the present invention, there is provided an exhaust gas treatment method for treating exhaust gases collected from at least one PFC dealing device which deals with a PFC gas in an exhaust gas treatment system including an exhaust emission line through which the exhaust gases collected, an external exhaust gas disposal device purifying the exhaust gases for exhaust emission, a gas treatment device eliminating the PFC gas, a gas treatment line branched from the exhaust emission line and connected to the gas treatment device, and an intermediate line connected between the gas treatment device and the external exhaust gas disposal device, the method comprising the steps of: 
         [0017]    switching from the exhaust emission line to the gas treatment line to supply the exhaust gases to the gas treatment device; 
         [0018]    making the gas treatment device eliminate the PFC gas from the exhaust gases; and proceed 
         [0019]    discharging the treated exhaust gases from the gas treatment device through the intermediate line to the external exhaust gas disposal device. 
         [0020]    The exhaust gas treatment method and the exhaust gas treatment system according to the present invention are capable of recovering Greenhouse effect gases e.g., PFC gases and the like with the gas treatment device e.g., the gas recovery device via the gas treatment line, although those gases have been conventionally expelled as exhaust gas and the like to the outside. Namely, the present invention enables to provide a counter measures for global warming concerning the exhaust gas expelled from not only the conventional etching step but also processing steps such as CVD and the like in the manufacturing processes for semiconductor devices, liquid crystal devices and the like. 
         [0021]    In addition, the exhaust gas treatment system mentioned above may further comprise a by-pass line connected between the gas treatment line and the intermediate line to detour around the gas treatment device, whereby prevention from stoppage of line (to stop operation of the semiconductor manufacturing equipment and the like) is achieved because of exhaust emission to the external exhaust gas disposal device even though the gas treatment device is stopped for some reason. 
     
    
     
       BRIEF EXPLANATION OF THE DRAWINGS 
         [0022]    The aforementioned aspects and other features of the invention are explained in the following description, taken in connection with the accompanying drawing figures wherein: 
           [0023]      FIG. 1  is a schematic diagram showing an example of a conventional treatment system for treating the exhaust gases of post-etching; 
           [0024]      FIG. 2  is a schematic diagram showing a exhaust gas treatment system of an embodiment according to the present invention; and 
           [0025]      FIG. 3  is a schematic diagram showing an exhaust gas treatment system of another embodiment according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0026]    Exemplary embodiments according to the present invention will be described in detail below with reference to the accompanying drawings. 
         [0027]    There is described an exhaust gas treatment method and system as an example of the present embodiment in which the PFC gas is recovered from the exhaust gases of post-etching expelled from the etching device with the exhaust gas suction pump in the semiconductor manufacturing processes. 
         [0028]      FIG. 2  is a schematic diagram showing the exhaust gas treatment system of such embodiment according to the present invention. 
         [0029]    As shown in  FIG. 2 , suction pumps for exhaust gas of post-etching  11 , attached to etching devices respectively in semiconductor manufacturing equipment (not shown), are connected via exhaust emission line valves  15   v  of open/close valve respectively to an exhaust emission line  15  connected to an external exhaust gas disposal device  14  in an exhaust emission system, in which each etching device is a PFC gas dealing device. The external exhaust gas disposal device  14  is provided with an external exhaust emission line  17  in order to pump out cleaned gases to the outside. 
         [0030]    Further, the suction pumps for exhaust gas of post-etching  11  are connected via gas collecting line valves  16   v  of open/close valve respectively to a gas collecting line  16  (i.e., gas treatment line branched from the exhaust emission line) which is connected to a gas recovery device  12 . The gas recovery device  12  is provided with an intermediate line  18  from which residue gases processed, in which PFC gas is extracted from the exhaust gases, are expelled to the exhaust emission line  15 . The gas collecting line  16  at the inlet side of the gas recovery device  12  is connected to the intermediate line  18  at the outlet side of the gas recovery device  12  via a by-pass line valve  13   v  and a by-pass line  13 . 
         [0031]    When every gas collecting line valve  16   v  is closed and every exhaust emission line valve  15   v  is opened, the exhaust gases pumped out from the suction pumps for exhaust gas of post-etching  11  attached to the etching device join and flow through the exhaust emission line  15  to the external exhaust gas disposal device  14 , and are processed therein and released from the external exhaust emission line  17  to the outside of the factory. The gas collecting line valve  16   v  and the exhaust emission line valve  15   v  function as switching valves to switch the exhaust gases of post-etching to the exhaust emission line  15  and/or the gas collecting line  16 . 
         [0032]    When every gas collecting line valve  16   v  is opened and every exhaust emission line valve  15   v  is closed, the exhaust gases flow in the gas collecting line  16  to the gas recovery device  12  in which a predetermined gas recovery treatment is carried out, then the treated gases are pumped out via the intermediate line  18  and the exhaust emission line  15  to the external exhaust gas disposal device  14 , and the treated cleaned gases are processed therein and released from the external exhaust emission line  17  to the outside of the factory. Further, normally the by-pass line valve  13   v  is closed. 
         [0033]    In the present embodiment, the switching valves switch the exhaust gases pumped out from the suction pump for exhaust gas of post-etching  11  to the gas collecting line  16 , and then the gas recovery device  12  extracts PFC gas from the exhaust gases to recovery the PFC gas. In addition, in case that an emergency situation and the like need to detour the gas recovery device  12 , the gas recovery device  12  may be detoured by opening the by-pass line valve  13   v  of the by-pass line  13 . 
         [0034]    Thus, in the exhaust gas treatment method of the present embodiment, the exhaust gases of post-etching are processed from the etching device through the exhaust emission line and the external exhaust gas disposal device  14  to clean the gases for exhaust emission, by using the exhaust gas treatment system, in which the exhaust gases of post-etching pumped from the etching device are switched from the exhaust emission line to the gas collecting line, and then the gas recovery device  12  connected to the gas collecting line carries out a step of eliminating the PFC gas from the exhaust gases of post-etching, and then a step of discharging the treated exhaust gases from the gas recovery device  12  (i.e., gas treatment device) through the intermediate line  18  to the external exhaust gas disposal device  14 . 
         [0035]    As shown in  FIG. 3 , in another embodiment according to the present invention, suction pumps for exhaust gas of post-etching  11 , attached to etching devices of PFC gas dealing device respectively in semiconductor manufacturing equipment, are connected via electric motor operated valves  25   v  of open/close valve respectively to an exhaust emission line  15  connected to an external exhaust gas disposal device  14  in an exhaust emission system, in which each electric motor operated valve  25   v  of the exhaust emission line is driven by an electrically controlled actuator. The external exhaust gas disposal device  14  is provided with an external exhaust emission line  17  in order to pump out cleaned gases to the outside. 
         [0036]    Further, the suction pumps for exhaust gas of post-etching  11  are connected via electric motor operated valves  26   v  of open/close valve respectively to a gas collecting line  16  which is connected to a gas recovery device  12 , in which each electric motor operated valve  26   v  of the gas collecting line is driven by an electrically controlled actuator. The gas recovery device  12  is provided with an intermediate line  18  from which residue gases processed, in which PFC gas is extracted from the exhaust gases, are expelled to the exhaust emission line  15 . The gas collecting line  16  at the inlet side of the gas recovery device  12  is connected to the intermediate line  18  at the outlet side of the gas recovery device  12  via an electric motor operated by-pass line valve  23   v  and a by-pass line  13 , in which the electric motor operated by-pass line valve  23   v  of the by-pass line is driven by an electrically controlled actuator. 
         [0037]    Furthermore, the gas recovery device  12  is provided with a sensor  21  which detects temperature, pressure etc. within the device to output a situational signal of the gas recovery device. 
         [0038]    This system includes a control unit  22  connected via control lines, in broken lines shown in  FIG. 3 , to the electric motor operated valve of the exhaust emission line  25   v,  the electric motor operated valve of the gas collecting line  26   v,  and the electric motor operated valve of the by-pass line valve  23   v  which are electrically controlled by the actuator subject to the control unit  22  receiving the output of the sensor  21  to monitor the condition of the gas recovery device  12 . The control unit  22  may be composed of a computer such as a PC and the like capable of automatic controlling and/or remote controlling the devices. 
         [0039]    When every electric motor operated valve  26   v  of the gas collecting line is closed and every electric motor operated valve  25   v  of the exhaust emission line is opened by signals from the control unit  22 , the exhaust gases pumped out from the suction pumps for exhaust gas of post-etching  11  attached to the etching device join and flow through the exhaust emission line  15  to the external exhaust gas disposal device  14 , and are processed therein and released from the external exhaust emission line  17  to the outside of the factory. 
         [0040]    When every electric motor operated valve  26   v  of the gas collecting line is opened and every electric motor operated valve  25   v  of the exhaust emission line is closed by signals from the control unit  22 , the exhaust gases flow in the gas collecting line  16  to the gas recovery device  12  in which a predetermined gas recovery treatment is carried out, then the treated gases are pumped out via the intermediate line  18  and the exhaust emission line  15  to the external exhaust gas disposal device  14 , and the treated cleaned gases are processed therein and released from the external exhaust emission line  17  to the outside of the factory. Further, normally the electric motor operated by-pass line valve  23   v  of the by-pass line is closed. 
         [0041]    Thus, due to the signals from the control unit  22 , the switching valves  25   v,    26   v  switch the exhaust gases pumped out from the suction pump for exhaust gas of post-etching  11  to the gas collecting line  16 , and then the gas recovery device  12  extracts PFC gas from the exhaust gases to recovery the PFC gas. 
         [0042]    When, due to the output signals from the sensor  21 , the control unit  22  detects an emergency situation and the like of the gas recovery device  12 , the control unit makes the electric motor operated by-pass line valve  23   v  of the by-pass line  13  open to detour the gas recovery device  12 . 
         [0043]    The position and number of the sensor  21  on the gas recovery device  12  is not particularly limited, the sensor  21  may be placed on the external exhaust gas disposal device  14 , the suction pump for exhaust gas of post-etching  11 , the main body of the etching device and the like. Further, the sort of the sensor is not particularly limited. Using the output signals from those sensors, the control unit  22  may be constituted so as to control not only the electric motor operated valve of the by-pass line valve  23   v  but also the electric motor operated valve of the exhaust emission line  25   v  and the electric motor operated valve of the gas collecting line  26   v.    
         [0044]    Although the gas recovery device has been described as a gas treatment device in the embodiment mentioned above, such gas recovery device is not limited in the present invention. Instead of the gas recovery device of the gas collecting line branched form the exhaust emission line, a PFC gases detoxification device (e.g., Combustion-type detoxification device, plasma-type detoxification device or the like) may be usable in the present invention for the gas treatment system of the gas treatment line branched form the exhaust emission line similarly to the above embodiment. The present invention is adaptable to not only the conventional etching step but also processing steps such as CVD and the like in the manufacturing processes for semiconductor devices, liquid crystal devices and the like. 
         [0045]    As mentioned above, according to the present invention, the gas treatment device scheme has the gas collecting line and the gas recovery device and the like in which the exhaust emission line and the gas collecting line are provided with the switching valves whereby the exhaust gas treatment suitable for counter measures for global warming is achieved and further, it may be adapted to the sensor and feedback system and the like using automatic control, remote control, detection of pressure and/or temperature and the like. 
         [0046]    It is understood that the foregoing description and accompanying drawings set forth the preferred embodiments of the invention at the present time. Various modifications, additions and alternative designs will, of course, become apparent to those skilled in the art in light of the foregoing teachings without departing from the spirit and scope of the disclosed invention. Thus, it should be appreciated that the invention is not limited to the disclosed embodiments but may be practiced within the full scope of the appended claims. 
         [0047]    This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2009-153860, filed Jun. 29, 2009, the entire contents of which are incorporated herein by reference.