Patent Abstract:
A semiconductor manufacturing apparatus comprises a discharge portion discharging a coating liquid onto a substrate; a gas supply tube supplying an inert gas into a liquid container that contains the coating liquid, and pressurizing an interior of the liquid container; a coating liquid supply tube airtightly supplying the coating liquid from the liquid container to the discharge portion using pressurization from the gas supply tube; a first connecting portion capable of attaching and detaching the liquid container to and from the coating liquid supply tube; a second connecting portion capable of attaching and detaching the liquid container to and from the gas supply tube; and a solvent supply tube supplying a solvent, which can dissolve the coating liquid, to the first connecting portion.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of application Ser. No. 11/246,145, filed Oct. 11, 2005 now abandoned, and is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2004-311927, filed on Oct. 27, 2004, the entire contents of both of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a semiconductor manufacturing apparatus, a liquid container and a semiconductor device manufacturing method. 
     2. Related Art 
     A semiconductor device such as a NAND flash memory is required to bury a silicon oxide film in a trench having a high aspect ratio so as to form deep STI (shallow trench isolation) in a narrow region. 
     To meet this demand, a film formation technique for using both an HDP (high density plasma) film and an SOG (spin on glass) film has been developed (see Japanese Patent No. 3178412). According to this technique, a silicon oxide film is deposited by HDP-CVD (chemical vapor deposition), and a film coated with a perhydropolysilazane liquid (hereinafter, “PSZ (Polysilazane)”) is coated on the silicon oxide film by spin coating. The coated film is then silicified by a cure treatment. It is thereby possible to bury the silicon oxide film in a trench having a high aspect ratio. 
       FIG. 14  is a conceptual view showing a conventional SOG step. Normally, a bottled PSZ liquid filled with nitrogen is commercially available. When a bottle cap is opened at a time of a used PSZ bottle being replaced by a new one, the air never fails to enter the bottles. In addition, during the replacement, the air may possibly enter a PSZ liquid supply nozzle from a tip end of the PSZ liquid supply nozzle. If so, the PSZ liquid unavoidably contacts with the air. 
     The PSZ developed to be silicified at a temperature as low as about several hundred Celsius (° C.) can react with water and oxygen as represented by Chemical Formula 1, and can be solidified even at a room temperature when being exposed to the atmosphere.
 
—(SiH 2 NH) n —+2 n O→ n SiO 2   +n NH 3   (Formula 1)
 
     When the PSZ is solidified in a piping from a PSZ container to a discharge nozzle, the solidified PSZ fixedly adheres onto a semiconductor substrate after being discharged together with the PSZ-coating liquid, thereby disadvantageously causing bulges, divots, and streaks. Even if the solidified PSZ is not formed, the air mixed into the piping and discharged onto the semiconductor substrate as air bubbles may possibly cause the bulges, divots, and streaks. Furthermore, the solidified PSZ may possibly damage the semiconductor substrate and a polishing cloth or cause a contamination during CMP (Chemical Mechanical Polish) process. 
     When the PSZ remains in the used container, the PSZ reacts with water and oxygen to generate ammonium (NH 3 ) and silane (SiH 4 ). The ammonium and silane bring about considerably serious environmental and safety problems. It is, therefore, difficult to manage and handle the PSZ and the PSZ container in manufacturing of semiconductor products. 
     In these circumstances, therefore, a semiconductor manufacturing apparatus, which airtightly transports a liquid to be coated on a substrate from a container to a discharge portion and suppresses the liquid from coming in contact with the air when the container is replaced by another one, has been desired. 
     Furthermore, a liquid container detachable from the semiconductor manufacturing apparatus, which airtightly transports the liquid to be coated on the substrate from the container to the discharge portion and suppresses the liquid from coming in contact with the air when the container is replaced by another one, has been desired. 
     SUMMARY OF THE INVENTION 
     A semiconductor manufacturing apparatus according to an embodiment of the present invention comprises a discharge portion discharging a coating liquid onto a substrate; a gas supply tube supplying an inert gas into a liquid container that contains the coating liquid, and pressurizing an interior of the liquid container; a coating liquid supply tube airtightly supplying the coating liquid from the liquid container to the discharge portion using pressurization from the gas supply tube; a first connecting portion capable of attaching and detaching the liquid container to and from the coating liquid supply tube; a second connecting portion capable of attaching and detaching the liquid container to and from the gas supply tube; and a solvent supply tube supplying a solvent, which can dissolve the coating liquid, to the first connecting portion. 
     A semiconductor manufacturing apparatus according to an embodiment of the present invention comprises a discharge portion discharging a coating liquid onto a substrate; a gas supply tube supplying an inert gas into a liquid container that contains the coating liquid, and pressurizing an interior of the liquid container; a coating liquid supply tube airtightly supplying the coating liquid from the liquid container to the discharge portion using pressurization from the gas supply tube; a first connecting portion capable of attaching and detaching the liquid container to and from the coating liquid supply tube; a second connecting portion capable of attaching and detaching the liquid container to and from the gas supply tube; and a liquid bath including the solvent capable of dissolving the coating liquid, 
     wherein the first connecting portion and the second connecting portion are present in the liquid bath. 
     A liquid container according to an embodiment of the present invention which contains a coating liquid and which is undesirable to expose to the atmosphere before utilizing for semiconductor manufacturing, the liquid container being attachable to or detachable from a semiconductor manufacturing apparatus, wherein 
     the liquid container seals a coating liquid and a protection liquid, which is lower specific gravity than that of the coating liquid and does not react with the coating liquid, in a pressurized atmosphere with an inert gas higher than the atmospheric pressure. 
     A semiconductor manufacturing method using a semiconductor manufacturing apparatus according to an embodiment of the present invention comprises a discharge portion discharging a coating liquid onto a substrate; a gas supply tube pressurizing an interior of the liquid container with an inert gas; a coating liquid supply tube airtightly supplying the coating liquid from the liquid container to the discharge portion using pressurization from the gas supply tube; a first connecting portion capable of attaching and detaching the liquid container to and from the coating liquid supply tube; a second connecting portion capable of attaching and detaching the liquid container to and from the gas supply tube; and an exhaust tube capable of reducing an internal pressure of the coating liquid supply tube including the first connecting portion: 
     the method comprising: 
     attaching the liquid container to the first connecting portion and the second connecting portion; 
     supplying the inert gas to the liquid container via the gas supply tube, thereby carrying the coating liquid to the discharge portion via the coating liquid supply tube; 
     discharging the coating liquid to the substrate from the discharge portion; 
     reducing an internal pressure of the liquid container via the exhaust tube and the second connecting portion after discharging the coating liquid; and 
     returning the coating liquid in the first connecting portion and the liquid supply tube to the liquid container by using the pressure in the liquid container. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a semiconductor manufacturing apparatus and a PSZ container according to a first embodiment of the present invention; 
         FIG. 2  shows a PSZ container  20 ; 
         FIG. 3  shows an operation for detaching the PSZ container  20 ; 
         FIG. 4  is a flowchart that shows a flow of an operation for detaching the PSZ container  20 ; 
         FIG. 5  is a flowchart that shows a flow of an operation for attaching the PSZ container  20 ; 
         FIG. 6  is a schematic diagram of a semiconductor manufacturing apparatus and a PSZ container according to a second embodiment of the present invention; 
         FIG. 7  is a cross-sectional view of a PSZ container according to the second embodiment; 
         FIG. 8  is a cross-sectional view of a PSZ container according to the second embodiment; 
         FIG. 9  is a cross-sectional view of a PSZ container according to a third embodiment of the present invention; 
         FIG. 10  is a schematic diagram of a semiconductor manufacturing apparatus and a PSZ container according to a fourth embodiment of the present invention; 
         FIG. 11  is a schematic diagram of a semiconductor manufacturing apparatus and a PSZ container according to a fifth embodiment of the present invention; 
         FIG. 12  is a schematic diagram of a semiconductor manufacturing apparatus and a PSZ container according to a sixth embodiment of the present invention; 
         FIG. 13  is a table that shows effects of the respective embodiments of the present invention; and 
         FIG. 14  is a schematic diagram showing a conventional SOG step. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereafter, exemplary embodiments of the present invention will be described more specifically with reference to the drawings. Note that the invention is not limited to the embodiments. 
     First Embodiment 
       FIG. 1  is a schematic diagram of a semiconductor manufacturing apparatus  10  and a PSZ container  20  according to a first embodiment of the present invention. The semiconductor manufacturing apparatus  10  is an apparatus for dropping a PSZ liquid from a discharge nozzle onto a semiconductor substrate, and spreading the PSZ liquid on the semiconductor substrate by spin coating at an SOG step. 
     The semiconductor manufacturing apparatus  10  includes a coating liquid discharge portion (not shown), a PSZ supply tube  12  serving as a coating liquid supply tube, a dibutyl ether supply tube (hereinafter, “DBE supply tube”)  15  serving as a solvent supply tube, a helium supply tube (hereinafter, “He supply tube”)  16  serving as a gas supply tube, an exhaust tube  17 , and branch tubes  13  and  14 . Since the discharge portion may be identical to the discharge nozzle shown in  FIG. 14 , it is not shown in  FIG. 1 . 
     The semiconductor manufacturing apparatus  10  also includes a connector C 1   a  serving as a first connecting portion and a connector C 2   a  serving as a second connecting portion. The PSZ supply tube  12  is connected to the connector C 1   a  through a valve  102 . One end of the branch tube  13  is connected to the PSZ supply tube  12  between the valve  102  and the connector C 1   a  through a valve  103 . The other end of the branch tube  13  is connected to one end of the branch tube  14  through a valve  104 , and also connected to the DBE supply tube  15  through a valve  105 . 
     The He supply tube  16  is connected to the connector C 2   a  through a valve  106 . The other end of the branch tube  14  is connected to the He supply tube  16  between the valve  106  and the connector C 2   a , and the exhaust tube  17  is connected to the He supply tube  16  through a valve  107 . A vacuum pomp, e.g., a turbomolecular pump, not shown, is connected to the exhaust pipe  17 . 
     As shown in  FIG. 2 , the PSZ container.  20  includes a pair of connectors C 1   b  and C 2   b  connectable to the connectors C 1   a  and C 2   a  of the semiconductor manufacturing apparatus  10 , respectively. The PSZ container  20  can be thereby attached to or detached from the PSZ supply tube  12  and the He supply tube  16 . 
     The PSZ container  20  also includes a PSZ outlet tube  21  provided from the connector C 1   b  to neighborhoods of a bottom of the container  20 , and a He inlet tube  22  provided from the connector C 2   b  to neighborhoods of an upper surface of the container  20 . Valves  101  and  100  are provided at the PSZ outlet tube  21  near the connector C 1   b  and the He inlet tube  22  near the connector C 2   b , respectively, whereby an interior of the PSZ container  20  is shut off from the atmosphere. 
     The PSZ container  20  is withdrawn in a sealed state after usage and recyclable by filling a PSZ liquid again into the container  20 . An inert gas as well as the PSZ liquid is filled into the PSZ container  20  with the inert gas pressurized at a slightly higher pressure than an atmospheric pressure. By doing so, the air is not mixed into the PSZ container  20 . The PSZ liquid is contained in the PSZ container  20  up to a portion near the valve  100  but contained so as not to reach the valve  100 . It is thereby possible to prevent air bubbles from being generated in the PSZ liquid. The PSZ liquid is contained in the PSZ container  20  in a state, for example, in which the PSZ liquid is dissolved into a solvent such as dibutyl ether (hereinafter, “DBE”). 
     The inert gas filled into the PSZ container  20  is preferably the same as the inert gas, i.e., helium gas supplied to the semiconductor manufacturing apparatus  10  for the following reasons. The helium possesses a property that it is insoluble with an organic solvent such as the PSZ or DBE, and the helium is less expensive than the other inert gas such as xenon. The PSZ container  20  and the semiconductor manufacturing apparatus  10  are preferably made of stainless steel (SUS). However, the material for the PSZ container  20  and the semiconductor manufacturing apparatus  10  is not limited to SUS but may be an arbitrary material that has good airtightness, that does not react with the PSZ, and that does not cause a metal contamination. 
     (PSZ Supply Operation) 
     When the PSZ liquid is supplied to the discharge portion, the PSZ supply tube  12  and the He supply tube  16  are used but the DBE supply tube  15  and the exhaust tube  17  are not used. Due to this, the valves  100 ,  101 ,  102 , and  106  are open whereas the valves  103 ,  104 ,  105 , and  107  are closed. In this state, the He supply tube  16  supplies the He gas to the PSZ container  20  to pressurize an interior of the PSZ container  20 . An internal atmospheric pressure of the PSZ container  20  is made thereby higher than a surrounding atmospheric pressure, so that the PSZ liquid is supplied to the discharge portion through the PSZ supply tube  12 . At this time, the PSZ supply tube  12  airtightly supplies the PSZ liquid from the PSZ container  20  to the discharge portion. The discharge portion discharges the coating liquid onto the semiconductor substrate (see  FIG. 14 ). 
     (PSZ Container Detachment Operation) 
       FIG. 3  shows a manner of detaching the PSZ container  20  from the semiconductor manufacturing apparatus  10 .  FIG. 4  is a flowchart that shows a flow of an operation for detaching the PSZ container  20 . With reference to  FIGS. 3 and 4 , the operation for detaching the PSZ container  20  will be described. 
     When the PSZ liquid is supplied to the discharge portion and a residual amount of the PSZ liquid in the PSZ container  20  is small, it is necessary to replace the PSZ container  20  by a new PSZ container  20 . At this time, if the valves  100 ,  101 ,  102 , and  106  are simply closed to disconnect the connector C 1   a  from the connector C 1   b  and the connector C 2   a  from the connector C 2   b , the PSZ liquid remaining in the PSZ supply tube  12  from the connector C 1   a  to the valve  102  may possibly come in contact with the air. 
     To prevent this contact, when the PSZ container  20  is detached, the valves  101 ,  102 , and  106  are closed in this order and the valve  107  is opened (at a step S 10 ). At this step, since the valves  100  and  107  are open, the exhaust pipe  17  communicates with the PSZ container  20  while the valves other than the valves  100  and  107  are closed. The internal pressure of the PSZ container  20  is thereby reduced to about 600 Torr through the exhaust tube  17  (at a step S 10 ). 
     After the valve  107  is closed, the valves  105 ,  103 , and  101  are opened in this order. At this time, the internal pressure of the PSZ container  20  is lower than the atmospheric pressure (about 760 Torr). Due to this, DBE is supplied into the PSZ container  20  through the DBE supply tube  15 , the branch tube  13 , the PSZ supply tube from the valve  102  to the connector C 1   a  (hereinafter, the PSZ supply tube  12  in this section will be referred to as “piping  12   a ”), and the PSZ outlet tube  21 . The PSZ liquid remaining in the piping  12   a  and the PSZ outlet tube  21  is thereby forced into the PSZ container  20 . At the same time, the piping  12   a  and the PSZ outlet tube  21  are filled with the DBE (at a step S 30 ). 
     After the internal pressure of the PSZ container  20  is identical to the atmospheric pressure, the valves  100  and  105  are closed (at a step S 40 ). The valves  106  and  104  are then opened in this order. The He supply tube  16  thereby communicates with the PSZ container  20  through the branch tubes  14  and  13 . By supplying the pressurized He gas from the He supply tube  16 , the DBE remaining in the branch tube  13 , the piping  12   a , and the PSZ outlet tube  21  is forced into the PSZ container  20  (at a step S 60 ). When the internal pressure of the PSZ container  20  reaches at about 900 Torr, the valves  103  and  106  are closed (at a step S 70 ). Thereafter, the connector C 1   a  is disconnected from the connector C 1   b , and the connector C 2   a  is disconnected from the connector C 2   b , and the used PSZ container  20  is detached from the semiconductor manufacturing apparatus  10  (at a step S 80 ). 
     Since the He gas at the higher pressure than the atmospheric pressure is filled into the used PSZ container  20 , the air is not mixed into the PSZ container  20 . It is, therefore, possible to prevent oxygen and water from reacting with the PSZ liquid in the PSZ container  20 . 
     When the used PSZ container  20  is detached from the semiconductor manufacturing apparatus  10 , the PSZ supply tube  12  from the valve  102  to the discharge portion is filled with the PSZ liquid. The piping  12   a  and a piping (hereinafter, “piping  21   a ”) from the connector C 1   b  of the PSZ container  20  to the valve  101  are exposed to the atmosphere. In this embodiment, however, the piping  12   a  is washed by the DBE used as the solvent for the PSZ liquid in the PSZ container  20 , no PSZ liquid remains in the piping  12   a . Therefore, no PSZ solid matter is generated in the pipings  12   a  and  21   a.    
     (PSZ Container Attachment Operation) 
       FIG. 5  is a flowchart that shows a flow of an operation for attaching the PSZ container  20  to the semiconductor manufacturing apparatus  10 . With reference to  FIGS. 1 and 5 , an operation for attaching the new PSZ container  20  to the apparatus  10  will be described. 
     Although no PSZ liquid is contained in the piping  21   a  of the new PSZ container  20 , the piping  21   a  is exposed to the atmosphere. Due to this, it is necessary to take care not to contact the air present in the pipings  12   a  and  21   a  with the PSZ liquid. 
     The new PSZ container  20  is connected to the semiconductor manufacturing apparatus  10  (at a step S 90 ). At this time, all the valves  100  to  107  are closed. The valves  107 ,  104 , and  103  are then opened in this order. Internal pressures of the piping  12   a  and the branch tubes  103  and  104  are reduced to 10 −4  to 10 −5  Torr (at a step S 100 ). 
     After closing the valves  107  and  104  in this order, the valve  101  is opened. At this time, a piping including the piping  12   a  from the valve  101  to the valve  103  and the branch tube  13  are in a low pressure state close to a vacuum. Therefore, the PSZ liquid in the PSZ container  20  promptly reaches close to the valve  104  (at a step S 110 ). 
     After closing the valve  103 , the valve  105  is opened. The PSZ liquid in the branch tube  13  is thereby mixed with the DBE (at a step S 120 ). 
     Next, the valve  106  is opened, the He gas is supplied into a crisscross piping partitioned by the valves  100 ,  107 ,  106 , and  104 , and an internal pressure of the crisscross piping is thereby returned to about 600 Torr (at a step S 130 ). After closing the valve  106 , the valve  100  is opened. At this time, the internal pressure of the crisscross piping partitioned by the valves  100 ,  107 ,  106 , and  104  is slightly lower than the atmospheric pressure. Due to this, a mixture liquid of the PSZ, and the DBE in the branch tube  13  is returned to at least the piping  12   a  (at a step S 140 ). Since the DBE liquid is used as the solvent for the PSZ liquid in the PSZ container  20 , no problem occurs even if a small amount of the mixture liquid enters the PSZ container  20 . It is noted that He air bubbles are sometimes mixed into this mixture liquid of the PSZ and the DBE. 
     After closing the valve  103 , the valve  106  is opened (at a step S 150 ). The PSZ liquid in the PSZ container  20  can be thereby supplied to the discharge portion through the PSZ supply tube  12 . Since the initially supplied liquid is either the mixture liquid of the PSZ and the DBE or the mixture liquid containing the He air bubbles, the liquid is disposed of. 
     When the amount of the PSZ liquid in the PSZ container  20  is reduced, the detachment operation and the attachment operation for detaching and attaching the PSZ container  20  are repeatedly carried out according to the steps S 10  to S 150 . As described above, according to the first embodiment, the PSZ liquid can be supplied to the discharge portion without exposure to the air. 
     In recent years, following an increase in the aspect ratio of STI, it has been difficult to bury the silicon oxide film in the trench. The STI in the NAND flash memory is, in particular, high in aspect ration as compared with a logic circuit, and required to bury the silicon oxide film in a non-tapered trench. 
     When the present embodiment is applied, such defects as bumps, divots, and streaks can be prevented even at manufacturing steps of a NAND flash memory with a trench having an opening width of, for example, 90 to 70 nm. This can contribute to an improvement in the yield of semiconductor devices. 
     Furthermore, in the used PSZ container  20 , the residual liquid does not contact with the atmosphere and no hazardous and ignitable gas such as ammonium or silane is generated. 
     The valves  102  to  105  are preferably gate valves, e.g., block valves, without any excessive space at branch portions. 
     Second Embodiment 
       FIG. 6  is a schematic diagram of a semiconductor manufacturing apparatus  40  and a PSZ container  50  according to a second embodiment of the present invention. The semiconductor manufacturing apparatus  40  differs from the semiconductor manufacturing apparatus shown in  FIG. 14  in that a tip end of a PSZ supply tube  42  is formed into a “J” shape. The other constituent elements of the semiconductor manufacturing apparatus  40  may be identical to those of the semiconductor manufacturing apparatus shown in  FIG. 14 . The PSZ container  50  contains not only a PSZ liquid but also a protection liquid  52  that shuts off the PSZ liquid from the atmosphere. The other constituent elements of the PSZ container  50  may be identical to those of the PSZ container shown in  FIG. 14 . 
     In the semiconductor manufacturing apparatus shown in  FIG. 14 , an end of the PSZ supply tube is directed downward. Due to this, when the PSZ container is attached to the semiconductor manufacturing apparatus, air bubbles tend to be mixed into the PSZ supply tube. When the air bubbles are oxygen or water bubbles, they may disadvantageously cause the PSZ liquid to be solidified. When the air bubbles are inert gas bubbles such as helium bubbles, the PSZ liquid is disadvantageously difficult to discharge from the discharge portion. 
     In the semiconductor manufacturing apparatus  40  according to the second embodiment, by contrast, an end of the PSZ supply tube  42  is directed upward. This can make it more difficult to mix air bubbles into the PSZ supply tube  42  when the PSZ container  50  is attached to the semiconductor manufacturing apparatus  40 . It is noted that the PSZ container  50  is attached to the semiconductor manufacturing apparatus  40  after a valve  501  is closed. By doing so, even while the PSZ container  50  is being attached to the apparatus  40 , the PSZ liquid remains at the tip end of the PSZ supply tube  42 . 
       FIGS. 7 and 8  are cross-sectional views of the PSZ container  50  according to the second embodiment.  FIG. 7  shows the PSZ container  50  when being attached to the semiconductor manufacturing apparatus  40 , and  FIG. 8  shows the PSZ container  50  when being detached from the semiconductor manufacturing apparatus  40 . 
     Desirable conditions for the protection liquid  52  that covers the PSZ in the PSZ container  50  are: no reaction with the PSZ liquid (condition 1), lower specific gravity than that of the PSZ liquid and no mixture with the PSZ liquid (condition 2), higher wettability with an inner wall of the PSZ container  50  than that of the PSZ liquid (condition 3), and non-inclusion of carbon (C) in impurities (condition 4). The conditions 1 and 2 are necessary conditions. Examples of a material that satisfies the conditions 1 and 2 include straight-chain-hydrocarbon and cyclic cyclohexane. 
     When the protection liquid  52  satisfies the conditions 1 and 2, the protection liquid  52  can cover a liquid level of the PSZ liquid in the PSZ container  50 . When the protection liquid  52  satisfies the conditions 3, the protection liquid  52  can cover the inner wall of the PSZ container  50  and the residual PSZ liquid tends to reside on a bottom of the PSZ container  50  as shown in  FIG. 8 . It is thereby possible to ensure that the PSZ liquid is shut off from the atmosphere. The condition 4 is intended to eliminate carbon that may have a conductive type of either p or n as much as possible. 
     In the second embodiment, when the new PSZ container  50  is attached to the semiconductor manufacturing apparatus  40 , the air enters the PSZ container  50 . However, since the protection liquid  52  covers the surface of the PSZ, it is possible to prevent contact of the PSZ with the air. Further, when the used PSZ container  50  is detached from the semiconductor manufacturing apparatus  40 , it is possible to prevent the contact of the PSZ liquid with the air since the protection film  52  covers the surface of the PSZ. In addition, while the PSZ liquid is being supplied, the liquid level of the PSZ is lowered. However, since the protection liquid  52  has a favorable wettability, the protection liquid  52  even covers the surface of the PSZ adhering to the inner wall of the PSZ container  50 . 
     As shown in  FIG. 8 , even if the PSZ container  50  is temporarily held at a different location, the air in the PSZ container  50  does not contact with the PSZ liquid and no ammonium or silane is, therefore, generated in the PSZ container  50 . 
     When the PSZ container  50  is attached to the semiconductor manufacturing apparatus  40 , the protection liquid  52  enters the PSZ supply tube  42 . However, since the specific gravity of the protection liquid  52  is lower than that of the PSZ liquid and the tip end of the PSZ supply tube  42  is J-shaped and directed upward, the protection liquid  52  surfaces on the tip end of the PSZ supply tube  42 . Therefore, the protection liquid  52  is not supplied to a discharge portion  44 . 
     In the second embodiment, the protection liquid  52  may be also used in a waste liquid container provided below a spin coater. If so, a waste liquid is thereby out of contact with the air. The second embodiment is, therefore, more preferable in environmental and safety aspects. 
     The semiconductor manufacturing apparatus  40  and the PSZ container  50  according to the second embodiment are relatively inexpensive and can be realized by simple changes in designs of the conventional semiconductor manufacturing apparatus and the conventional PSZ container, respectively. 
     Third Embodiment 
       FIG. 9  is a cross-sectional view of a semiconductor manufacturing apparatus  40  and a PSZ container  60  according to a third embodiment of the present invention. The PSZ container  60  according to the third embodiment includes a narrow opening portion  61  and a concave portion  63  that can accept a J-shaped tip end E of a PSZ supply tube  42 . The semiconductor manufacturing apparatus  40  is identical to the semiconductor manufacturing apparatus  40  according to the second embodiment. 
     According to the third embodiment, since the opening portion  61  is narrow, an area by which a PSZ liquid contacts with the air can be made small. In addition, by inserting the tip end E of the PSZ supply tube  42  into the concave portion  63 , the PSZ liquid can be made most use of to the end. 
     The semiconductor manufacturing apparatus  40  and the PSZ container  60  according to the third embodiment are also relatively inexpensive and can be realized by simple changes in designs of the conventional semiconductor manufacturing apparatus and the conventional PSZ container, respectively. 
     Fourth Embodiment 
       FIG. 10  is a schematic diagram of a semiconductor manufacturing apparatus  70  and a PSZ container  80  according to a fourth embodiment of the present invention. The semiconductor manufacturing apparatus  70  differs from the semiconductor manufacturing apparatus shown in  FIG. 14  in that the apparatus  70  includes a liquid bath  73  that contains a DBE liquid. A PSZ supply tube  72  and a He supply tube  71  are inserted into the liquid bath  73 , and a tip end of the PSZ supply tube  72  and that of the He supply tube  71  are arranged below a liquid level of the DBE liquid. 
     Female connectors  75  are provided at tip ends of the He supply tube  71  and the PSZ supply tube  72 , respectively, and corresponding male connectors  85  having a valve are provided at the PSZ container  80 . By one-touch connection between the female connectors  75  and the corresponding male connectors  85 , the PSZ container  80  is connected to the He supply tube  71  and the PSZ supply tube  72 . 
     Attachment and detachment of the PSZ container  80  to and from the semiconductor manufacturing apparatus  70  are executed in the DBE liquid. Therefore, the air does not contact with the PSZ liquid. Since the DBE liquid is contained in the PSZ container  80  as a solvent for the PSZ liquid, no problem occurs even if a small amount of the DBE liquid is mixed into the PSZ container  80 . 
     Furthermore, the semiconductor manufacturing apparatus and the PSZ container  80  according to the fourth embodiment are also relatively inexpensive, and can be realized by simple changes in designs of the conventional semiconductor manufacturing apparatus and the conventional PSZ container, respectively. 
     A material for the PSZ container  80  may be a flexible material such as polyethylene in place of glass. When the PSZ container  80  consists of the flexible material and the air is mixed into the male connectors  85 , the air can be easily removed by an operator&#39;s compressing the PSZ container  80  by an operator&#39;s hand after the PSZ container  80  is dipped into the liquid bath  73 . It is noted that the DBE liquid does not flow backward into the PSZ container  80  since the respective male connectors  85  include valves. 
     Fifth Embodiment 
       FIG. 11  is a schematic diagram of a semiconductor manufacturing apparatus and a PSZ container  80  according to a fifth embodiment of the present invention. The fifth embodiment differs from the fourth embodiment in a shape of a liquid bath.  91 . Other constituent elements in the fifth embodiment may be identical to those in the fourth embodiment. A region R 1  of the liquid bath  91 , into which a tip end of a He supply tube  71  and that of a PSZ supply tube  72  are inserted, is filled with a DBE liquid. Therefore, a PSZ liquid does not contact with not only the air but also a gas such as He. 
     A region R 2  of the liquid bath  91  has an upper opening portion. The PSZ container  80  can be attached to the He supply tube  71  and the PSZ supply tube  72  by operator&#39;s inserting the PSZ container  80  into the liquid bath  91  from this opening portion. The liquid bath  91  includes a porthole  93 . The operator can, therefore, connect the PSZ container  80  to the He supply tube  71  and the PSZ supply tube  72  while viewing the liquid bath  91  from the porthole  93 . 
     Sixth Embodiment 
       FIG. 12  is a schematic diagram of a semiconductor manufacturing apparatus and a PSZ container  81  according to a sixth embodiment of the present invention. In the fourth and the fifth embodiments, the attachment and detachment of the PSZ container are executed in the DBE liquid. In the sixth embodiment, the attachment and detachment of the PSZ container are executed in a He gas atmosphere. 
     An upper portion of a region R 1  of the PSZ container  81  is filled with the He gas. A liquid bath  92  includes a supply port  350  for supplying the He gas and an exhaust port  351  for exhausting the air or the like mixed into the liquid bath  92  together with the He gas. By so constituting, even if the gas other than the He gas is mixed into the PSZ container  81  while the PSZ container  81  is being replaced with another container  81 , the gas can be exhausted. 
     In the semiconductor manufacturing apparatus, a connector C 3   a  is connected to a PSZ supply tube  312  through a valve  310 , and also connected to a balloon  360  through a valve  309 . A connector C 4   a  is connected to a He supply tube  316 . The balloon  360  consists of, for example, a rubber having a high elasticity and a low reaction with the PSZ liquid. The balloon  360  is filled with the PSZ liquid in advance. A valve  307  is provided at the He supply tube  316 , and an exhaust tube  317  is connected between the valve  307  and the connector C 4   a  through a valve  308 . 
     A PSZ outlet tube  321  and a He inlet tube  322  of the PSZ container  81  include two valves  304  and  306  and two valves  303  and  305 , respectively. Connectors C 3   b  and C 4   b  of the PSZ outlet tube  321  and the He inlet tube  322  are formed to be directed downward. The PSZ outlet tube  321  from the PSZ container  81  to the valve  304  is filled with the PSZ liquid in advance, and a piping between the valves  303  and  305  and a piping between the valves  304  and  306  are each filled with a pressurized He gas in advance. 
     An operation for attaching the PSZ container  81  to the semiconductor manufacturing apparatus will be described. The PSZ container  81  is moved into the liquid bath  92  so that the connectors C 3   b  and C 4   b  are provided in the He gas atmosphere in the region R 1  (at a step S 300 ). At this time, the air may possibly remain in a piping from the valve  306  to the connector C 3   b  and a piping from the valve  305  to the connector C 4   b . Considering this, by opening the valves  305  and  306 , the pressurized He gas is ejected (at a step S 310 ). By doing so, the air is discharged to the outside of the connectors C 3   b  and C 4   b . Since the air is higher in specific gravity than the He gas, the air is moved to a liquid level of the DBE liquid and exhausted from the exhaust port  351 . 
     Thereafter, the connector C 3   a  is connected to the connector C 3   b  and the connector C 4   a  is connected to the connector C 4   b  (at a step S 320 ). At this time, the valves  307 ,  308 ,  309 , and  310  are closed. The valves  309  and  308  are then opened in this order (at a step S 330 ). The balloon  360  filled with the PSZ liquid is thereby contracted and the He gas residing in a piping from the valve  304  to the valve  309  is returned into the PSZ container  81 . 
     After closing the valves  308  and  309  in this order, the valves  307  and  310  are opened in this order (at a step S 340 ). The He supply tube  316  thereby supplies the He gas into the PSZ container  81  and the PSZ liquid is supplied to a discharge portion through the PSZ supply tube  312 . 
     When the PSZ container  81  is to be detached from the semiconductor manufacturing apparatus, then the valve  310  is closed, and the valve  309  is closed after the balloon  360  is filled with the PSZ liquid to some degree. After closing all the valves  303  to  308 , the PSZ container  81  is detached. 
     According to the fifth embodiment, the PSZ container  81  can be replaced by a new PSZ container  81  in an environment shut off from the air while preventing mixture of the He gas. 
     As described above, in the embodiments, it is preferable that the PSZ liquid is discharged onto a dummy wafer before being coated on a desired wafer. This is because the DBE liquid may possibly enter the PSZ container  81  during the replacement. 
     The embodiments may be executed in combination. For example, the PSZ container  50  shown in  FIGS. 7 and 8  can be applied to any one of the first and the third to the fifth embodiments. 
       FIG. 13  is a table that shows effects of the respective embodiments. In the table of  FIG. 13 , the numbers of particles generated when the PSZ liquid is coated on the semiconductor substrate at the SOG step are shown. In the conventional technique shown in  FIG. 14 , many particles having respective particle diameters are generated. In the first to the sixth embodiments, particles having particle diameters of 0.2 to 1.0 μm are hardly generated. According to the embodiments of the present invention, therefore, it is expected to improve the yield of semiconductor devices. 
     In the respective embodiments of the present invention, the coating liquid is not limited to the PSZ liquid but may be any coating liquid for forming a silica-containing film or the like.

Technology Classification (CPC): 1