Patent Publication Number: US-2005139234-A1

Title: Method of cleaning substrate processing apparatus and computer-readable recording medium

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This is a Continuation-in-part Application of PCT Application No. PCT/JP03/08318, filed on Jul. 1, 2003, which was not published under PCT Article 21(2) in English. This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-197364, filed Jul. 5, 2002, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a method of cleaning a substrate processing apparatus that processes a substrate and to a computer-readable recording medium.  
      2. Description of the Related Art  
      As a film deposition apparatus for forming a thin film made of a high-dielectric substance such as HfO 2  on a semiconductor wafer (hereinafter, simply referred to as a “wafer”), a film deposition apparatus that chemically forms a thin film has been conventionally known. In such a film deposition apparatus, a wafer is heated and a process gas is used to form a thin film on the wafer.  
      The high-dielectric substance adheres to an inner wall of a process chamber, a susceptor disposed in the process chamber, and so on after the thin film is formed on the wafer. If the thin film of the high-dielectric substance is formed on the wafer while the inner wall of the process chamber and so on have the high-dielectric substance adhering thereto, the high-dielectric substance adhering to the inner wall of the process chamber and so on sometimes peels off the inner wall of the process chamber and so on to contaminate the wafer. In order to prevent this, the inside of the process chamber is regularly cleaned to remove the high-dielectric substance adhering to the inner wall of the process chamber and so on.  
      Various methods are currently used for cleaning the inside of the process chamber. For example, Japanese Patent Laid-open Application No. 2000-96241 describes a cleaning method of the inside of a process chamber by using hexafluoroacetylacetone (Hhfac) or the like. Here, this patent document describes that the cleaning condition are such that the temperature of the inside of the process chamber is 200° C. to 300° C. and the pressure in the process chamber is lower than 200 Pa. However, there is a problem that a sufficient cleaning effect cannot be obtained under this condition.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention was made in order to solve the conventional problems stated above. Specifically, it is an object of the present invention to provide a method of cleaning a substrate processing apparatus capable of providing a sufficient cleaning effect and to provide a computer-readable recording medium.  
      A method of cleaning a substrate processing apparatus according to one of the aspects of the present invention includes: supplying a cleaning gas containing β-diketone and one of water and alcohol into a process chamber of the substrate processing apparatus, with an insulative substance adhering to an inner part thereof, while the process chamber is set under a temperature that has been raised to not lower than 300° C. nor higher than 450° C., to cause a reaction of the insulative substance and the β-diketone contained in the cleaning gas, thereby forming a complex of a substance composing the insulative substance; and discharging the complex out of the process chamber. The method of cleaning the substrate processing apparatus of this invention can provide a sufficient cleaning effect since it includes the forming of the complex using one of water and alcohol as a catalyst.  
      A method of cleaning a substrate processing apparatus according to another aspect of the present invention includes: supplying a cleaning gas containing hexafluoroacetylacetone into a process chamber of the substrate processing apparatus having an insulative substance adhering to an inner part thereof, while the process chamber is set under a temperature that has been raised to not lower than 300° C. nor higher than 450° C. and the inner part of the process chamber is kept at a pressure of not lower than 1.33×10 3  Pa nor higher than 1.33×10 4  Pa, to cause a reaction of the insulative substance and the hexafluoroacetylacetone contained in the cleaning gas, thereby forming a complex of a substance composing the insulative substance; and discharging the complex out of the process chamber. The method of cleaning the substrate processing apparatus of this invention can provide a sufficient cleaning effect since it includes the optimum forming of the complex.  
      A method of cleaning a substrate processing apparatus according to still another aspect of the present invention includes: supplying a cleaning gas containing β-diketone and oxygen into a process chamber of the substrate processing apparatus having an insulative substance adhering to an inner part thereof, to cause a reaction of the insulative substance and the β-diketone, thereby forming a complex of a substance composing the insulative substance; and discharging the complex out of the process chamber. The method of cleaning the substrate processing apparatus of this invention can provide a sufficient cleaning effect since it includes the forming of the complex.  
      Preferably, the forming of the complex and the discharge of the complex are alternately repeated. Such repetition of the forming of the complex and the discharge of the complex results in more reliable formation and discharge of the complex.  
      The insulative substance may be a high-dielectric substance containing at least one kind out of aluminum (Al), zirconium (Zr), hafnium (Hf), lanthanum (La), yttrium (Y), praseodymium (Pr), and cerium (Ce). Even when such a high-dielectric substance adheres to the inside of the process chamber, it is possible to surely remove the high-dielectric substance from the process chamber.  
      Preferably, a content ratio of one of the water and the alcohol in the cleaning gas is not lower than 50 ppm nor higher than 5000 ppm. The cleaning gas containing the water or alcohol at such a ratio can further improve cleaning efficiency.  
      Preferably, the cleaning gas contains an oxygen gas. When the oxygen is contained in the cleaning gas, a sufficient cleaning effect can be obtained.  
      Preferably, the β-diketone is a substance represented as R 1 (CO)CH 2 (CO)R 2 , R 1  and R 2  independently are an alkyl and a haloalkyl. The use of such a substance as the β-diketone makes it possible to surely form the complex.  
      Preferably, the β-diketone is hexafluoroacetylacetone. The use of hexafluoroacetylacetone as the β-diketone facilitates forming the complex.  
      A recording medium according to yet another aspect of the present invention is a computer-readable recording medium in which a computer program controlling a substrate processing apparatus is recorded, wherein the computer program comprises: controlling the substrate processing apparatus to supply a cleaning gas containing β-diketone and one of water and alcohol into a process chamber of the substrate processing apparatus having an insulative substance adhering to an inner part thereof, while the process chamber is set under a temperature that has been raised to not lower than 300° C. nor higher than 450° C., to cause a reaction of the insulative substance and the β-diketone contained in the cleaning gas, thereby forming a complex of a substance composing the insulative substance; and controlling the substrate processing apparatus to discharge the complex out of the process chamber.  
      A recording medium according to yet another aspect of the present invention is a computer-readable recording medium in which a computer program controlling a substrate processing apparatus is recorded, wherein the computer program comprises: controlling the substrate processing apparatus to supply a cleaning gas containing hexafluoroacetylacetone into a process chamber of the substrate processing apparatus having an insulative substance adhering to an inner part thereof, while the process chamber is set under a temperature that has been raised to not lower than 300° C. nor higher than 450° C. and the inner part of the process chamber is kept at a pressure of not lower than 1.33×10 3  Pa nor higher than 1.33×10 4  Pa, to cause a reaction of the insulative substance and the hexafluoroacetylacetone contained in the cleaning gas, thereby forming a complex of a substance composing the insulative substance; and controlling the substrate processing apparatus to discharge the complex out of the process chamber.  
      According to yet another aspect of a recording medium of the present invention is a computer-readable recording medium in which a computer program controlling a substrate processing apparatus is recorded, wherein the computer program comprises: controlling the substrate processing apparatus to supply a cleaning gas containing β-diketone and oxygen into a process chamber of the substrate processing apparatus having an insulative substance adhering to an inner part thereof, to cause a reaction of the insulative substance and the β-diketone, thereby forming a complex of a substance composing the insulative substance; and controlling the substrate processing apparatus to discharge the complex out of the process chamber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a vertical cross-sectional view schematically showing a CVD apparatus according to a first embodiment.  
       FIG. 2  is a view schematically showing a process gas supply system and a cleaning gas supply system of the CVD apparatus according to the first embodiment.  
       FIG. 3  is a flowchart showing the flow of film deposition performed in the CVD apparatus according to the first embodiment.  
       FIG. 4  is a flowchart showing the flow of cleaning of the CVD apparatus according to the first embodiment.  
       FIG. 5A  and  FIG. 5B  are vertical cross-sectional views schematically showing a cleaning process of the CVD apparatus according to the first embodiment.  
       FIG. 6A  and  FIG. 6B  are graphs showing the correlation between the temperature of a susceptor of the CVD apparatus and the etch rate of an insulative film formed on a wafer, according to an example 1.  
       FIG. 7A  is a diagram schematically showing a chemical structure of Hhfac and  FIG. 7B  is a diagram schematically showing a chemical structure of a metal complex formed by Hhfac.  
       FIG. 8A  and  FIG. 8B  are graphs showing the correlation between the temperature of the susceptor of the CVD apparatus and the etch rate of an insulative film formed on a wafer, according to a comparative example 1.  
       FIG. 9A  and  FIG. 9B  are graphs showing the correlation between the temperature of the susceptor of the CVD apparatus and the etch rate of an insulative film formed on a wafer, according to a comparative example 2.  
       FIG. 10  is a graph showing the correlation between the flow rate of O 2  and the etch rate of a HfO 2  film, according to an example 2.  
       FIG. 11A  to  FIG. 11C  are graphs showing the correlation of the etch rate of a HfO 2  film relative to the process pressure of a cleaning gas, the process temperature, and the flow rate of Hhfac, according to an example 3.  
       FIG. 12A  is a graph showing the correlation between the concentration of water in a cleaning gas and the etch rate of a Hfo 2  film and  FIG. 12B  is a graph showing the correlation between the concentration of ethanol in a cleaning gas and the etch rate of a HfO 2  film.  
       FIG. 13  is a flow chart showing the flow of cleaning of the CVD apparatus, according to a second embodiment.  
       FIG. 14A  and  FIG. 14B  are vertical cross-sectional views schematically showing a cleaning process of the CVD apparatus according to the second embodiment.  
       FIG. 15  is a flowchart showing the flow of cleaning of the CVD apparatus, according to a third embodiment. 
    
    
     DESCRIPTION OF THE EMBODIMENTS  
     First Embodiment  
      Hereinafter, a substrate processing apparatus according to a first embodiment of the present invention will be described. In the description of this embodiment, a CVD (Chemical Vapor Deposition) apparatus to chemically form a thin film on a film deposition surface of a wafer as a substrate will be used as the substrate processing apparatus.  FIG. 1  is a vertical cross-sectional view schematically showing the CVD apparatus according to this embodiment.  
      As shown in  FIG. 1 , a CVD apparatus  1  is formed of, for example, aluminum or stainless steel and has a substantially cylindrical shape. The CVD apparatus  1  has a process chamber  3  having an O-ring  2  provided therein.  
      A showerhead  4  is disposed on a ceiling of the process chamber  3  via an O-ring  5  to face a later-described susceptor  19 . The showerhead  4  supplies into the process chamber  3  a process gas for forming a thin film of an insulative substance on a film deposition surface of a wafer W and a cleaning gas for removing the insulative substance that adheres to the inside of the process chamber during film deposition.  
      The showerhead  4  has a hollow structure and a plurality of discharge ports  6  are bored in a bottom of the showerhead  4 . The plural discharge ports  6  are bored, so that the process gas and the cleaning gas supplied into the showerhead  4  can be uniformly discharged.  
      A later-described process gas supply system  7  to supply the process gas and a later-described cleaning gas supply system  9  to supply the cleaning gas are attached to a top portion of the showerhead  4 .  
      Vacuum exhaust systems  10  to vacuum-exhaust the inside of the process chamber  3  are connected to a bottom of the process chamber  3 . Each of the vacuum exhaust systems  10  is mainly composed of a vacuum pump  11  such as a turbo-molecular pump or a dry pump, an exhaust pipe  12  connected to the vacuum pump  11  and the bottom of the process chamber  3 , a shutoff valve  13  disposed in the middle of the exhaust pipe  12  and opening/closing to start or stop the vacuum exhaust, and a pressure control valve 14  disposed in the middle of the exhaust pipe  12  and opening/closing to control the pressure inside the process chamber  3 .  
      A resistance heating element  15  to heat the process chamber  3  is wound around an outer wall of the process chamber  3 . Further, an opening is formed in a sidewall of the process chamber  3 , and a gate valve  16  that is opened/closed when the wafer W is carried into/out of the process chamber  3  is disposed along the opening with an O-ring  17  interposed therebetween.  
      Further, a purge gas supply system  18  to supply a purge gas such as, for example, a nitrogen gas that returns the pressure inside the process chamber  3  to the atmospheric pressure before the gate valve  16  is opened is connected to the sidewall of the process chamber  3 .  
      The disc-shaped susceptor  19  to place the wafer W thereon is disposed at a position facing the showerhead  4  in the process chamber  3 . The susceptor  19  is formed of, for example, aluminum nitride, silicon nitride, amorphous carbon, or composite carbon. The susceptor  19  is inserted in the process chamber  3  through an opening formed in the bottom of the process chamber  3 . When the CVD apparatus  1  is in operation, a thin film of an insulative substance is formed on the film deposition surface of the wafer W while the wafer W is on an upper surface of the susceptor  19 .  
      Inside the susceptor  19  or around the susceptor  19 , a susceptor heater, for example, a resistance heating element or a heating lamp, for heating the susceptor  19  is disposed. In this embodiment, a case where a resistance heating element  20  is used as the susceptor heater will be described. The resistance heating element  20  is electrically connected to an external power source  21  disposed outside the process chamber  3 .  
      Lifter holes  22  are bored in, for example, three places of the susceptor  19  to pass through the susceptor  19  in an up/down direction. Under the lifter holes  22 , three lifter pins  23  movable in the up/down direction are disposed. When the lifter pins  23  are moved up/down by a not-shown hoisting/lowering device, the wafer W is placed on the susceptor  19  or is made apart from the susceptor  19 .  
      The lifter pins  23  pass through the outer wall of the process chamber  3  and an extendible/contractible bellows  24  made of metal is disposed in a portion of the process chamber  3  through which the lifter pins  23  pass. Therefore, the inside of the process chamber  3  is kept airtight.  
      A control unit  25  is electrically connected to the process gas supply system  7 , the cleaning gas supply system  9 , the vacuum exhaust systems  10 , the resistance heating elements  15 ,  20 , and so on. The control unit  25  comprises: a computer  26  configured to controlling the operations of the CVD apparatus  1  based on a program to be described next; and a computer-readable recording medium  27  in which the program controlling the CVD apparatus  1  is recorded. The program comprises controlling the CVD apparatus  1  to execute a film deposition process (Step  1 ) and a cleaning process (Step  2 ) which will be described later.  
      The computer  26  stores the program recorded in the recording medium  27 , for example, in its own memory. Then, the computer  26  reads the program from its own memory to control the CVD apparatus  1  based on the program, so that the CVD apparatus  1  executes the film deposition process and the cleaning process.  
      Examples of the recording medium  27  are a magnetic recording device, an optical disc, a magneto-optical recording medium, a semiconductor memory, and the like. Examples of the magnetic recording device are a hard disc device (HDD), a flexible disc (FD), a magnetic tape, and the like. Examples of the optical disc are a DVD (Digital Versatile Disc), a DVD-RAM (Random Access Memory), a CD-ROM (Compact Disc Read Only Memory), a CD-R (Recordable)/RW (ReWritable), and the like. Examples of the magneto-optical recording medium are a MO (Magneto-Optical Disc) and the like. Examples of the semiconductor memory are a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.  
      Next, the process gas supply system  7  and the cleaning gas supply system  9  of the CVD apparatus  1  according to this embodiment will be described.  FIG. 2  is a view schematically showing the process gas supply system  7  and the cleaning gas supply system  9  of the CVD apparatus  1  according to this embodiment. As shown in  FIG. 2 , the process gas supply system  7  has a pipe  72  whose one end is connected to the top portion of the showerhead  4  and whose other end is connected to a carrier gas tank  71  containing a carrier gas such as an argon gas. In the description below, the showerhead  4  side is defined as a downstream side and the carrier gas tank  71  side is defined as an upstream side.  
      The pipe  72  passes through a later-described process gas mixer  82  to be branched off into a plurality of systems, for example, three systems. Source tanks  73 A to  73 C containing sources to compose the process gas, for example, a hafnium-based source, a zirconium-based source, and an aluminum-based source are connected to pipes  72 A to  72 C into which the pipe  72  is branched off, via first bypass pipes  75 A to  75 C and second bypass pipes  77 A to  77 C which will be described later.  
      The source tank  73 A contains, for example, Hf(t-OC 4 H 9 ) 4  or Hf[N(C 2 H 5 ) 2 ] 4  as the hafnium-based source. The source tank  73 B contains, for example, Zr(t-OC 4 H 9 ) 4  or Zr[N(C 2 H 5 ) 2 ] 4  as the zirconium-based source. The source tank  73 C contains, for example, Al(OC 2 H 5 ) 3  or Al(OCH 3 ) 3  as the aluminum-based source.  
      The first bypass pipes  75 A to  75 C having valves  74 A to  74 C in the middle thereof are connected to the pipes  72 A to  72 C and the source tanks  73 A to  73 C respectively. Further, the second bypass pipes  77 A to  77 C positioned on the downstream side of the first bypass pipes  75 A to  75 C and having valves  76 A to  76 C in the middle thereof are connected to the pipes  72 A to  72 C and the source tanks  73 A to  73 C respectively. When the valves  74 A to  74 C are opened and the carrier gas is supplied into the source tanks  73 A to  73 C through the first bypass pipes  75 A to  75 C to be bubbled, the sources contained in the source tanks  73 A to  73 C vaporize. These vaporized sources are introduced into the pipes  72 A to  72 C through the second bypass pipes  77 A to  77 C.  
      Mass flow controllers  78 A to  78 C and valves  79 A to  79 C are disposed on the upstream side of the first bypass pipes  75 A to  75 C in the pipes  72 A to  72 C. The flow rate of the carrier gas is adjusted by adjusting the mass flow controllers  78 A to  78 C.  
      Needle valves  80 A to  80 C are disposed on the downstream side of the second bypass pipes  77 A to  77 C in the pipes  72 A to  72 C. By adjusting the needle valves  80 A to  80 C, the pressures inside the source tanks  73 A to  73 C and supply amounts of the sources are adjusted.  
      Further, valves  81 A and  81 C are disposed between the first bypass pipes  75 A to  75 C and the second bypass pipes  77 A to  77 C in the pipes  72 A to  72 C.  
      The process gas mixer  82  is connected to the three-branched pipes  72 A to  72 C, so that it is possible to selectively supply one of the sources in the source tanks  73 A to  73 C or to supply a process gas in which the sources vaporized in the source tanks  73 A to  73 C are mixed at a predetermined ratio, as required.  
      An oxygen source  73 D such as an oxygen cylinder is connected to the process gas mixer  82  via a pipe  72 D. A valve  80 D is disposed in the middle of the pipe  72 D to adjust the flow rate of the oxygen.  
      A valve  83  is disposed on the downstream side of the process gas mixer  82  in the pipe  72 . When the valve  83  is opened, the process gas composed of a single source or the mixed process gas is supplied to the showerhead  4  at a predetermined flow rate.  
      The cleaning gas supply system  9  adopts substantially the same structure as that of the process gas supply system  7  described above. Specifically, a valve  93 , a mass flow controller  94 , a valve  95 , a needle valve  96 , and a cleaning gas mixer  140  are disposed in the middle of a pipe  92  from the upstream side toward the downstream side. Here, the showerhead  4  side is defined as a downstream side and a side of a carrier gas tank  91  containing a carrier gas is defined as an upstream side.  
      Further, a first bypass pipe  98  having a valve  97  disposed in the middle thereof is connected to the pipe  92  at a position between the mass flow controller  94  and the valve  95 , and a second bypass pipe  100  having a valve  99  in the middle thereof is connected to the pipe  92  at a position between the valve  95  and the needle valve  96 .  
      A water or ethanol supply system  130 , a N 2  supply system  110 , and an O 2  supply system  120  are connected to the cleaning gas mixer  140 . Water or ethanol in the water or ethanol tank  131 , N 2  in the N 2  cylinder  111 , and O 2  in the O 2  cylinder  121  are mixed at a predetermined ratio to be supplied as a mixed cleaning gas. Around the water or ethanol tank  131 , a heater  132  for heating and vaporizing the water or ethanol is disposed.  
      A Hhfac tank  101  containing hexafluoroacetylacetone (Hhfac) as β-diketone is connected to the first and second bypass pipes  98 ,  100 . Here, as the β-diketone, β-diketone such as, for example, Hhfac in which an alkyl bonded with a carbonyl has a halogen atom is preferably used. Such β-diketone is preferable because a halogen atom is high in inductive effect and this effect reduces electron density of an oxygen atom of the carbonyl, so that a hydrogen atom bonded with the oxygen atom is easily dissociated as a hydrogen ion. Reactivity is higher as the dissociation more easily occurs.  
      When the valve  97  of the first bypass pipe  98  is opened and the carrier gas is supplied from the first bypass pipe  98  into the Hhfac tank  101  for bubbling, the Hhfac contained in the Hhfac tank  101  vaporizes. The vaporized Hhfac is sent to the cleaning gas mixer  140  through the second bypass pipe  100  and the pipe  92  to be mixed with O 2 , N 2 , and water or ethanol at a predetermined ratio, and the resultant gas is supplied into the showerhead  4  as the cleaning gas.  
      Next, the flows of the film deposition process performed in the CVD apparatus  1  and the cleaning process of the CVD apparatus  1  according to this embodiment will be described. It is assumed that the vacuum pumps  11  are in operation during the film deposition process and the cleaning process.  
       FIG. 3  is a flowchart showing the flow of the film deposition performed in the CVD apparatus  1  according to this embodiment, and  FIG. 4  is a flowchart showing the flow of the cleaning of the CVD apparatus  1  according to this embodiment.  FIG. 5A  and  FIG. 5B  are vertical cross-sectional views schematically showing the cleaning process of the CVD apparatus  1  according to this embodiment.  
      First, the film deposition process performed in the CVD apparatus  1  will be described (Step  1 ). Note that the program for the CVD apparatus  1  to execute Step  1 ( 1 ) to Step  1 ( 5 ), which will be described below, is recorded in the recording medium  27 . The computer  26  reads the program recorded in the recording medium  27  and the computer  26  controls the CVD apparatus  1  based on the program, so that these steps are executed by the CVD apparatus  1 .  
      First, the not-shown external power source supplies electric current to the resistance heating element  15  and the external power source  21  supplies electric current to the resistance heating element  20  to heat the process chamber  3  and the susceptor  19  to a film deposition temperature (Step  1 ( 1 )).  
      After the process chamber  3  and the susceptor  19  are heated to the film deposition temperature, the gate valve  16  is opened and a not-shown transfer arm carries a wafer W on which a thin film of an insulative substance is not formed into the process chamber  3  to place the wafer W on the lifter pins  23  which have been lifted. Thereafter, the lifter pins  23  move down to place the wafer W on the susceptor  19  (Step  1 ( 2 )).  
      After the wafer W is placed on the susceptor  19 , the valve  79 A, the valve  74 A, the valve  76 A, the needle valves  80 A,  80 D, and the valve  83  are opened, and the carrier gas is supplied into the source tank  73 A at a flow rate adjusted by the mass flow controller  78 A. The carrier gas bubbles the source in the source tank  73 A to vaporize the source. The vaporized sources are introduced to the process gas mixer  82  to be mixed therein, and thereafter the mixed gas is supplied into the showerhead  4  as the process gas. The process gas is discharged from the discharge ports  6  of the showerhead  4 , so that the formation of the thin film of the insulative substance is started on the film deposition surface of the wafer W. When the film deposition is to be started, the shutoff valves  13  are opened to vacuum-exhaust the inside of the process chamber  4  (Step  1 ( 3 )).  
      Here, when the thin film of the insulative substance is formed on the wafer W, the insulative substance also adheres to the inside of the process chamber  3 , specifically, for example, an inner wall of the process chamber  3  and the susceptor  19 .  
      After the thin film of the insulative substance is formed on the wafer W, the valve  79 A, the valve  74 A, the valve  76 A, the needle valves  80 A,  80 D, and the valve  83  are closed to stop the supply of the process gas, thereby finishing the formation of the thin film of the insulative substance (Step  1 ( 4 )).  
      Thereafter, the lifter pins  23  move up to bring the wafer W apart from the susceptor  19 , and the gate valve  16  is opened while the purge gas is supplied. Then, the wafer W on which the thin film of the insulative substance is formed is carried out of the process chamber  3  by the not-shown transfer arm (Step  1 ( 5 )).  
      Next, the cleaning process of the inside of the process chamber  3  will be described (Step  2 ). Note that the program for the CVD apparatus  1  to execute Step  2 ( 1 A) to Step  2 ( 3 A), which will be described below, is recorded in the recording medium  27 . The computer  26  reads the program recorded in the recording medium  27  and the computer  26  controls the CVD apparatus  1  based on the program, so that these steps are executed by the CVD apparatus  1 .  
      After the wafer W on which the thin film of the insulative substance is formed is carried out of the process chamber  3 , the resistance heating element  15  heats the process chamber  3  to not lower than 300° C. nor higher than 450° C., preferably, not lower than 350° C. nor higher than 425° C. (Step  2 ( 1 A)).  
      After the process chamber  3  is heated to not lower than 300° C. nor higher than 450° C., the valve  93 , the valve  97 , the valve  99 , and the needle valve  96  are opened, and the carrier gas is supplied into the Hhfac tank  101  while the flow rate of the carrier gas is adjusted by the mass flow controller  94 . This carrier gas bubbles Hhfac in the Hhfac tank  101  to vaporize the Hhfac. The Hhfac vaporized by the bubbling is mixed with water or ethanol, N 2 , and O 2  in the cleaning gas mixer  140 , and the resultant gas is supplied as the cleaning gas into the process chamber  3  through the showerhead  4 . This is the start of the cleaning of the inside of the process chamber  3 . Further, in this embodiment, the shutoff valves  13  are opened for vacuum exhaust during the cleaning (Step  2 ( 2 A)). Here, the pressure inside the process chamber  3  during the cleaning is kept at not lower than 1.33× 10   3  Pa nor higher than 1.33× 10   4  Pa. More preferably, the pressure inside the process chamber  3  during the cleaning is kept at not lower than 3.33×10 3  Pa nor higher than 9.96×10 3  Pa.  
      Phenomena occurring during the cleaning will be specifically described. First, the Hhfac contained in the cleaning gas disperses in the process chamber  3  to come into contact with the insulative substance adhering to the inside of the process chamber  3 . When the Hhfac comes in contact with the insulative substance, the Hhfac and the insulative substance react with each other to form a complex of a substance composing the insulative substance as shown in  FIG. 5A . Further, the inside of the process chamber  3  is vacuum-exhausted because the shutoff valves  13  are open. Consequently, the complex easily vaporizes to become apart from the inner wall of the process chamber  3  and from the susceptor  19 . Moreover, the complex that has been apart therefrom is quickly discharged outside the process chamber  3  through the exhaust pipes  12  as shown in  FIG. 5B , so that the insulative substance is removed from the inside of the process chamber  3 .  
      After the insulative substance adhering to the inside of the process chamber  3  is fully removed, the valve  93 , the valve  97 , the valve  99 , and the needle valve  96  are closed to stop the supply of the cleaning gas, thereby finishing the cleaning of the inside of the process chamber (Step  2 ( 3 A)).  
      This embodiment can provide a sufficient cleaning effect since the cleaning is performed while the processing chamber  3  is under the temperature which has been raised to not lower than 300° C. nor higher than 450° C. Specifically, when the cleaning is performed while the process chamber  3  is under the temperature which has been raised to not lower than 300° C. nor higher than 450° C., the decomposition of the Hhfac contained in the cleaning gas is inhibited. Consequently, the insulative substance and the Hhfac easily react with each other, so that the complex of the substance composing the insulative substance is easily formed. Therefore, a sufficient cleaning effect can be obtained.  
      In this embodiment, the pressure inside the process chamber  3  is kept at not lower than 1.33×10 3  Pa nor higher than 1.33×10 4  Pa during the cleaning, so that a sufficient cleaning effect can be obtained. Specifically, when the pressure inside the process chamber  3  is kept at not lower than 1.33×10 3  Pa nor higher than 1.33×10 4  Pa during the cleaning, the complex of the substance composing the insulative substance easily vaporizes. Moreover, the frequency of the collision of the Hhfac with the insulative substrate is increased, so that the complex of the substance composing the insulative substance is easily formed. Therefore, a sufficient cleaning effect can be obtained.  
      In this embodiment, since the cleaning gas contains O 2 , a sufficient cleaning effect can be obtained.  
      In this embodiment, since the shutoff valves  13  are opened for vacuum exhaust during the cleaning, the complex of the substance composing the insulative substance can be vaporized immediately after being produced.  
      In this embodiment, since the insulative substance is directly complexed by Hhfac, the number of processes for the cleaning is small and it is possible to easily remove the insulative substance adhering to the inside of the process chamber  3  in a short time.  
      In this embodiment, since Hhfac easily reacting with the insulative substance is used as β-diketone, it is possible to more surely remove the insulative substance from the process chamber  3 .  
     EXAMPLE 1  
      Hereinafter, an example 1 will be described. In this example, the CVD apparatus  1  described in the first embodiment was used, and the removal rate in the use of HfO 2  as an insulative substance and the removal rate in the use of Al 2 O 3  as an insulative substance were measured under varied temperatures. Here, in this example, HfO 2  or Al 2 O 3  adhering to the inner wall of the CVD apparatus  1  and the susceptor  19  was not removed, but a wafer W on which a thin film of HfO 2  or Al 2 O 3  was formed was placed on the susceptor  19  in the CVD apparatus  1  and a thin film of HfO 2  or Al 2 O 3  formed on the wafer W was removed by a cleaning gas.  
      Hhfac, N 2 , and O 2  were supplied into the process chamber  3  at flow rates of 375 sccm, 20 sccm, and 50 sccm respectively. Note that the cleaning gas contained water whose contents was 1000 ppm. Further, the pressure control valves  14  were adjusted to keep the pressure inside the processing chamber  3  at about 6.65×10 3  Pa during the cleaning.  
      The cleaning was conducted for 10 minutes under varied temperatures while the inside of the process chamber  3  was kept in the above-described state.  FIG. 6A  is a graph showing the correlation between the temperature of the susceptor  19  of the CVD apparatus  1  and the etch rate of HfO 2  formed on the wafer W, according to this example, and  FIG. 6B  is a graph showing the correlation between the temperature of the susceptor  19  of the CVD apparatus  1  and the etch rate of Al 2 O 3  formed on the wafer W, according to this example.  
      As shown in  FIG. 6A , it has been confirmed that the etch rate of HfO 2  rises in a temperature range from 350° C. to 400° C. Further, as shown in  FIG. 6B , it has been confirmed that the etch rate of Al 2 O 3  rises to reach its peak in a temperature range from 300° C. to 400° C. Incidentally, the etch rate in  FIG. 6B  is represented using kcps (kilo counts per second) which represents intensity of X-ray fluorescence proportional to the number of metal atoms in fluorescent X-ray analysis, instead of a physical film thickness.  
       FIG. 7A  is a diagram schematically showing a chemical structure of Hhfac, and  FIG. 7B  is a diagram schematically showing a chemical structure of a metal complex formed by Hhfac. β-diketone such as Hhfac has tautomerism. Therefore, Hhfac can take two structures of a structure I and a structure II as shown in  FIG. 7A .  
      As a result, shared electrons are delocalized in C═O bond and C—C bond. This causes easy separation of O—H bond of the structure II. If a positively charged atom such as a metal atom M exists near Hhfac in this state, it is thought that Hhfac with the structure II in which the O—H bond is separated coordinates to form a complex as in  FIG. 7B . It is thought that since a state of a complex that is formed when a plurality of Hhfac coordinate to the metal atom M is produced, the complex is easily removed from the inner chamber. Incidentally, it is thought that β-diketone, not limited to Hhfac, causes such a reaction.  
      As described above, when Hhfac is used for cleaning the process chamber  3  following the method according to the first embodiment described above, the process chamber  3  can be sufficiently cleaned under a feasible temperature range of not lower than 300° C. nor higher than 450° C.  
     COMPARATIVE EXAMPLE 1  
      A comparative example 1 will be described below. In this comparative example, the same apparatus as that used in the example 1 described above was used, and a cleaning experiment was conducted under the same conditions as those of the example 1 described above except that Cl remote plasma was used instead of Hhfac.  FIG. 8A  and  FIG. 8B  show the results.  FIG. 8A  is a graph showing the correlation between the temperature of the susceptor  19  of the CVD apparatus  1  and the etch rate of HfO 2  formed on the wafer W, according to this comparative example, and  FIG. 8B  is a graph showing the correlation between the temperature of the susceptor  19  of the CVD apparatus  1  and the etch rate of Al 2 O 3  formed on the wafer W, according to this comparative example.  
      As shown in  FIG. 8A , it has been confirmed that the etch rate of HfO 2  rises to reach its peak in a temperature range from 300° C. to 400° C., but it has been confirmed that the cleaning rate is lower than that when Hhfac is used.  
      On the other hand, as seen in the result in  FIG. 8B , the etch rate of Al 2 O 3  is extremely low in a feasible temperature range of not lower than 300° C. nor higher than 400° C. No sign showing the improvement in the etch rate is observed even when the temperature is raised to 400° C. or higher. It is inferred from these results that it is difficult to clean off Al 2 O 3  by using Cl remote plasma.  
      As described above, it has been confirmed that it is difficult to clean off the insulative substance by using Cl remote plasma.  
     COMPARATIVE EXAMPLE 2  
      Hereinafter, a comparative example 2 will be described. In this comparative example, the same apparatus as that used in the example 1 described above was used, and a cleaning experiment was conducted under the same conditions as those of the example 1 described above except that NF 3  remote plasma was used instead of Hhfac.  FIG. 9A  and  FIG. 9B  show the results.  FIG. 9A  is a graph showing the correlation between the temperature of the susceptor  19  of the CVD apparatus  1  and the etch rate of HfO 2  formed on the wafer W, according to this comparative example, and  FIG. 9B  is a graph showing the correlation between the temperature of the susceptor  19  of the CVD apparatus  1  and the etch rate of Al 2 O 3  formed on the wafer W, according to this comparative example.  
      As shown in  FIG. 9A , it has been confirmed that the etch rate of HfO 2  shows an increasing tendency in a temperature range of 400° C. to 500° C. Judging from this result, it is inferred that it is necessary to raise the temperature of the inside of the chamber to 400° C. or higher in order to clean off HfO 2  by using NF 3  remote plasma.  
      On the other hand, as is seen in the result in  FIG. 9B , the etch rate of Al 2 O 3  is extremely low in a feasible temperature range of not lower than 300° C. nor higher than 400° C. No sign of the improvement in the etch rate is observed even when the temperature is raised to a high temperature of 400° C. or higher. It is inferred from this result that it is difficult to clean off Al 2 O 3  by using NF 3  remote plasma.  
      As described above, it is necessary to keep the inside of the chamber at a high temperature of 400° C. or higher when NF 3  remote plasma is used for the cleaning, but it has been confirmed that there is some case where an insulative substance cannot be cleaned off even at the high temperature of 400° C. or higher, depending on the kind of the insulative substance. In other words, it has been confirmed that the cleaning in a feasible temperature range of not lower than 300° C. to nor higher than 400° C. is difficult.  
     EXAMPLE 2  
      Hereinafter, an example 2 of the present invention will be described. In this example, the same apparatus as that used in the example 1 described above was used and the correlation between the flow rate of O 2  contained in the cleaning gas and the etch rate was studied. Hhfac and N 2  were mixed at a ratio of Hhfac:N 2 =375:200 (sccm). The water content in this mixed gas was 1000 ppm. This mixed gas was supplied into the chamber at a pressure of 6.65×10 3  Pa, and O 2  was supplied into the chamber. The etch rate of a HfO 2  film was measured while the flow rate of O 2  was gradually increased.  FIG. 10  shows the result.  
       FIG. 10  is a graph in which the flow rate of O 2  is taken on the horizontal axis and the etch rate of the HfO 2  film is plotted on the vertical axis. AS is apparent from the graph in  FIG. 10 , it was observed that the etch rate of the HfO 2  film remarkably improves when O 2  is supplied at a flow rate of 50 sccm compared with a case where O 2  is not supplied. It is inferred from this result that the cleaning gas preferably contains O 2 .  
     EXAMPLE 3  
      Hereinafter, an example 3 of the present invention will be described. In this example, the same apparatus as that used in the example 1 described above was used, and the optimum condition for cleaning was studied. A mixed gas of Hhfac, O 2 , and N 2  was used as a cleaning gas. The water content in this mixed gas was 1000 ppm.  
      The mixed gas was supplied into the chamber, and it was studied how changes in the process pressure, process temperature, and flow rate of Hhfac influence the process result.  FIG. 11A  to  FIG. 11C  show the results.  
       FIG. 11A  is a graph in which the process pressure of the cleaning gas is taken on the horizontal axis and the etch rate of a HfO 2  film is plotted on the vertical axis. The process conditions were such that the flow rate ratio of Hhfac/O 2 /N 2  was 375/50/200 (sccm), the process temperature was 400° C., and the water content was 1000 ppm.  
      As is apparent from the graph in  FIG. 11A , the etch rate reaches its peak when the process pressure of the cleaning gas is about 6.65×10 3  Pa. The reason for this is thought to be that the frequency of the collision of Hhfac in the cleaning gas with HfO 2  and the elimination speed of the produced complex reach the respective peaks when the process pressure of the cleaning gas is about 6.65×10 3  Pa.  
       FIG. 11B  is a graph in which the process temperature of the cleaning gas is taken on the horizontal axis and the etch rate of a HfO 2  film is plotted on the vertical axis. The process conditions were such that the flow rate ratio of Hhfac/O 2 /N 2  was 375/50/200 (sccm), the process pressure was 6.65×10 3  Pa, and the water content was 1000 ppm.  
      As is apparent from the graph in  FIG. 11B , the etch rate reaches its peak when the process temperature is about 400° C. The reason for this is thought to be that a heat quantity of about 400° C. is required for Hhfac in the cleaning gas to coordinate to a Hf atom.  
      On the other hand, the etch rate drastically lowers when the process temperature reaches about 425° C. The reason for this is thought to be that Hhfac itself decomposes due to the heat when the process temperature reaches 425° C.  
       FIG. 11C  is a graph in which the flow rate of Hhfac in the cleaning gas is taken on the horizontal axis and the etch rate of a HfO 2  film is plotted on the vertical axis. The process conditions were such that the composition ratio of Hhfac:O 2 : N 2  was 375:50:20, the process temperature was 400° C., and the water content was 1000 ppm.  
      As is apparent from the graph in  FIG. 1C , the etch rate reaches its peak when the flow rate of Hhfac in the cleaning gas is about 375 sccm.  
      On the other hand, the etch rate drastically lowers when the flow rate of Hhfac in the cleaning gas reaches about 450 sccm. The reason for this is thought to be that the surface temperature of an object to be processed drops when the flow rate of Hhfac reaches about 450 sccm or higher.  
     EXAMPLE 4  
      Hereinafter, an example 4 of the present invention will be described. In this example, the same apparatus as that used in the example 1 described above was used and the influences of water and so on contained in the cleaning gas were studied.  FIG. 12A  and  FIG. 12B  show the results.  FIG. 12A  is a graph in which the concentration of water in the cleaning gas is taken on the horizontal axis and the etch rate of a Hfo 2  film is plotted on the vertical axis.  FIG. 12B  is a graph in which the concentration of ethanol in the cleaning gas is taken on the horizontal axis and the etch rate of a HfO 2  film is plotted on the vertical axis.  
      The process conditions were such that the flow rate ratio of Hhfac/N 2 /O 2  was 375/200/50 (sccm) and the process pressure was 6.65×10 3  Pa. As is apparent from  FIG. 12A , the etch rate shows a gradual increase when the concentration of water is in a range from 0 ppm to about 600 ppm, and reaches its peak when the water concentration is about 700 ppm. Further, as is apparent from  FIG. 12B , the rise of the etch rate was confirmed when the concentration of the ethanol was 1000 ppm.  
      It is inferred from these results that the concentration of water or ethanol contained in the cleaning gas, though depending on the kind of a substance to be cleaned, preferably falls approximately in a range of not lower than 50 ppm nor higher than 5000 ppm, and more preferably in a range not lower than 100 ppm nor higher than 1000 ppm.  
     Second Embodiment  
      Hereinafter, a second embodiment of the present invention will be described. In this embodiment and an embodiment to follow, the same contents as those in a preceding embodiment will not be described.  
      In this embodiment, after a cleaning gas is stored in the process chamber  3  and an insulative substance adhering to the inside of the process chamber  3  is complexed, the inside of the process chamber  3  is vacuum-exhausted.  
       FIG. 13  is a flowchart showing the flow of cleaning of the CVD apparatus  1  according to this embodiment, and  FIG. 14A  and  FIG. 14B  are vertical cross-sectional views schematically showing a cleaning process of the CVD apparatus  1  according to this embodiment.  
      The cleaning process of this embodiment is executed by the computer  26  reading a program recorded in the recording medium  27  and controlling the CVD apparatus  1  based on the program, as in the first embodiment. Note that a program for the CVD apparatus  1  to execute Step  2 ( 1 B) to Step  2 ( 3 B), which will be described below, is recorded in the recording medium  27 .  
      First, after a wafer W on which a thin film of an insulative substance is formed is carried out of the process chamber  3 , the resistance heating element  15  wound around the outer wall of the process chamber  3  heats the process chamber  3  (Step  2 ( 1 B)).  
      After the process chamber  3  is heated, the valve  93 , the valve  97 , the valve  99 , and the needle valve  96  are opened to supply the cleaning gas into the process chamber  3  (Step  2 ( 2 B)).  
      When the cleaning gas disperses in the process chamber  3  to come into contact with the insulative substance adhering to the inside of the process chamber  3 , a complex of a substance composing the insulative substance is formed. Here in this embodiment, the shutoff valves  13  are closed, and as shown in  FIG. 14A , the cleaning gas supplied into the process chamber  3  is stored without any vacuum exhaust.  
      After the complex is fully formed, the valve  93 , the valve  97 , the valve  99 , and the needle valve  96  are closed to stop the supply of a carrier gas and a cleaning gas, and the shutoff valves  13  are opened to vacuum-exhaust the inside of the process chamber  3  (Step  2 ( 3 B)). The complex vaporizes due to this vacuum exhaust to be apart from the inner wall of the process chamber  3  and the susceptor  19  as shown in  FIG. 14B  and to be quickly discharged out of the process chamber  3  through the exhaust pipes  12 . Thereafter, the complex is fully discharged out of the process chamber  3  to finish the cleaning.  
      As described above, in this embodiment, the inside of the process chamber  3  is vacuum-exhausted after the cleaning gas is stored in the process chamber  3  and the complex of the substance composing the insulative substance is formed. Therefore, the cleaning gas disperses to every corner of the inside of the process chamber  3 , which can provide a unique effect that the insulative substance adhering to the inside of the process chamber  3  can be more surely removed. In addition, since the inside of the process chamber  3  is vacuum-exhausted after the cleaning gas is stored therein, it is possible to save the cleaning gas to realize cost reduction.  
     Third Embodiment  
      Hereinafter, a third embodiment will be described. In this embodiment, a series of processes of storing a cleaning gas in the process chamber  3  to form a complex of a substance composing an insulative substance, and thereafter vacuum-exhausting the inside of the process chamber  3  are intermittently repeated.  FIG. 15  is a flowchart showing the flow of cleaning of the CVD apparatus according to this embodiment.  
      The cleaning process of this embodiment is executed by the computer  26  reading a program recorded in the recording medium  27  and controlling the CVD apparatus  1  based on the program, as in the first embodiment. Note that a program for the CVD apparatus  1  to execute Step  2 ( 1 C) to Step  2 ( 4 C), which will be described below, is recorded in the recording medium  27 .  
      As shown in  FIG. 15 , after a wafer W on which a thin film of the insulative substance is formed is carried out of the process chamber  3 , the resistance heating element  15  heats the process chamber  3  (Step  2 ( 1 C)).  
      After the process chamber  3  is heated, the valve  93 , the valve  97 , the valve  99 , and the needle valve  96  are opened and the cleaning gas is supplied into the process chamber  3  to form the complex of the substance composing the insulative substance (Step  2 ( 2 C)). After the complex is fully formed, the valve  93 , the valve  97 , the valve  99 , and the needle valve  96  are closed to stop the supply of the cleaning gas, and the shutoff valves  13  are opened to vacuum-exhaust the inside of the process chamber  3  (Step  2 ( 3 C)).  
      After the complex is fully discharged out of the process chamber  3 , an amount of the insulative substance adhering to the inside of the process chamber  3  is checked (Step  2  ( 4 C)). This check work can be conducted by directly checking the adhesion state of the insulative substance to the inner wall of the process chamber  3  or by checking a residual amount of a thin film of the insulative substance formed on a monitoring wafer. Alternatively, the amount of the adhering insulative substance can be checked by infrared spectroscopy, using a not-shown observation window provided in the process chamber  3 . When the result of checking the amount of the insulative substance adhering to the inside of the process chamber  3  shows that the insulative substance adhering to the inside of the process chamber  3  is fully removed, the cleaning is finished.  
      On the other hand, when the result of checking the amount of the insulative substance adhering to the inside of the process chamber  3  shows that the insulative substance adhering to the inside of the process chamber  3  is not fully removed, the operations of Step  2  ( 2 C) to Step  2  ( 4 C) described above are repeated and the cleaning operation is continued until there finally remains no insulative substance adhering to the inside of the process chamber  3 .  
      As described above, in this embodiment, a series of the processes of storing the cleaning gas in the process chamber  3  to form the complex of the substance composing the insulative substance and thereafter vacuum-exhausting the inside of the process chamber  3  is intermittently repeated, resulting in the complete formation and discharge of the complex. This can provide a unique effect that the insulative substance adhering to the inside of the process chamber  3  can be removed efficiently.  
      It should be noted that the present invention is not limited to the contents described in the above first to third embodiments. The structure, materials, arrangement of the members, and so on can be appropriately changed without departing from the spirit of the present invention. For example, in describing the first to third embodiments, the CVD apparatus  1  utilizing heat is used as a CVD apparatus. However, a CVD apparatus utilizing plasma is also usable.  
      In describing the first to third embodiments, the CVD apparatus  1  is used as a substrate processing apparatus. However, a film deposition apparatus such as a physical vapor deposition apparatus (PVD apparatus) and a plating apparatus, an etching apparatus, or a chemical mechanical polishing apparatus (CMP apparatus) are also usable. Moreover, in describing the first to third embodiments, the wafer W is used as a substrate. However, a LCD glass substrate for liquid crystal is also usable.