Patent Publication Number: US-2006008595-A1

Title: Film-forming method

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a film-forming method of forming a film containing metal on a substrate to be processed.  
      2. Description of the Related Art  
      In recent years, with high-performance of semiconductor devices, a high integration of a semiconductor device progresses, and the demand for miniaturization becomes remarkable. The wiring rule is developed into an area of 0.10 μm or less. As for a thin film used for forming such a high-performance semiconductor device, a high-quality film is required, such as less impurity in the film and good crystal orientation. Further, it is required to have good coverage when forming a micro-pattern.  
      As for a film-forming method satisfying the above-mentioned requirements, there is suggested a method of obtaining a thin film having a predetermined thickness by forming the film with a level close to an atomic layer or a molecular layer according to adsorption of a plurality of kinds of process gases onto a reaction surface while supplying the process gases alternately on an individual kind basis when forming the film and repeating those processes. Such a film-forming method may be referred to as an Atomic Layer Deposition method (ALD method).  
      An outline of such a film-forming method according to the ALD method is explained below. First, a process chamber is prepared that has a first gas supply path for supplying a first gas and a second gas supply path for supplying a second gas. The first and the second gases are supplied alternately into the process chamber. Specifically, the first gas is supplied first onto a substrate in the process chamber so as to form an adsorption layer on the substrate. Thereafter, the second gas is supplied onto the substrate so as to react with the first gas. This process is repeated for a predetermined times as needed. According to this method, since the first gas react with the second gas after it is adsorbed onto the substrate, a film-forming temperature can be reduced. Additionally, a high-quality film having less impurity can be obtained. In forming a micro pattern there is no void being formed due to reaction and consumption of a process gas on an upper portion of a hole, which is a problem in a conventional CVD method, thereby providing a good coverage characteristic.  
      According to the above-mentioned film-forming method, a film containing a metal can be formed using a gas containing the metal as the first gas and a reducing gas reducing the first gas as the second gas. For example, a film of Ta, Tan, Ti, TiN, W, WN, etc., can be formed.  
      In a case of forming TiN film as an example, the TiN film can be formed using a compound, such as TiCl 4 , containing Ti as the above-mentioned first process gas and a reducing gas containing nitrogen such as plasma-excited NH 3  as the above-mentioned second process gas. In such a case, the reason for using the plasma-excited NH 3  is to reduce in-film impurity concentration of the TiN film formed.  
      Since the film formed by the above-mentioned film-forming method has a high-quality and is excellent in a coverage characteristic, there is a case in which the film is used for a Cu diffusion preventing film, which is formed between an insulating film and a copper layer in formation of Cu wiring in a semiconductor device.  
      However, when the film-forming method of forming a film by supplying a plurality of gases into a process chamber, there may be a case in which the plurality of gases area mixed in an area other than the reaction surface of the substrate to be processed, which produces generation sources of particles. For example, when performing an atomic level or a molecular level film formation by supplying alternately the above-mentioned first and second gases, the gases supplied into the process chamber may diffuse or enter into a gas supply path of gases other than the gas concerned, which causes a problem in that the gases are mixed and react with each other.  
      For example, there is a case in which, when supplying the second gas into the process chamber through the second gas supply path, the second gas enters the first gas supply path, which results in the first gas and the second gas being react with each other and a particle generation source is produced.  
      Additionally, if a method of supplying a reverse-flow preventing gas such as Ar is used as means for preventing such a mixture of gases, there is a problem in that the reverse prevention gives influences to the film formation. For example, when plasma excitation is performed in a film-forming process, the reverse-flow preventing gas may be plasma-excited, which results in generation of ions due to ionization of the reverse-flow preventing gas. The ions may generate sputtering of a wall surface of the process chamber, and there is a problem in that particles and impurities scatter in the process chamber.  
     SUMMARY OF THE INVENTION  
      It is a general object of the present invention to provide an improved and useful film-forming method in which the above-mentioned problems are eliminated.  
      More specific object of the present invention is to provide a film-forming method which can prevent a plurality of gases from being mixed with each other in a gas supply path when forming a film on a substrate to be processed using the plurality of gases so as to prevent generation of particles to enable a stable and clean film formation.  
      In order to achieve the above-mentioned objects, there is provided according to the present invention a film-forming method of forming a film containing metal on a substrate to be processed by supplying a first process gas containing the metal and a second process gas for reducing the first process gas to a process chamber, comprising: a first step of supplying the first process gas from a first gas supply passage to the process chamber; and a second step of supplying the second process gas from a second gas supply passage to the process chamber and exciting plasma of the second process gas by plasma exciting means provided to the process chamber, wherein, in the second step, a first reverse flow preventing gas consisting of H 2  or He is supplied to the process chamber from the first gas supply passage.  
      In the film-forming method according to the present invention, the first step and the second step may be repeated alternately for a plurality of times.  
      The film-forming method according to the present invention may further comprise a step of purging the process chamber after each of the first step and the second step.  
      In the film-forming method according to the present invention, in the first step, a second reverse flow preventing gas may be supplied to the process chamber from the second gas supply passage. The second process gas and the first reverse flow preventing gas may be the same kind of gas. The second process gas may be H 2 . The first reverse flow preventing gas may be H 2 . The second reverse flow preventing gas may be Ar.  
      In the film-forming method according to the present invention, the metal may be one of Ta, Ti and W.  
      In the film-forming method according to the present invention, the first process gas may be one of an amide compound gas, a halogen compound gas and a carbonyl compound gas. The amide compound gas may be a gas selected from a group consisting of Ta(NC(CH 3 ) 2 (C 2 H 5 )(N(CH 3 ) 2 ) 3 , Ta[N(C 2 H 5 CH 3 )]  5 , Ta[N(CH 3 ) 2 ] 5 , Ta(NC(CH 3 ) 3 (N(C 2 H 5 ) 2 ) 3 , Ta(NC(CH 3 ) 3 (N(CH 3 ) 2 ) 3 , Ta(NC 2 H 5 )(N(C 2 H 5 ) 2 ) 3 , Ta(N(C 2 H 5 ) 2 (N(C 2 H 5 ) 2 ) 3 , Ti[N(C 2 H 5 CH 3 )] 4 , Ti[N(CH 3 ) 2 ] 4  and Ti[N(C 2 H 5 ) 2 ] 4 . The halogen compound gas may be a gas selected from a group consisting of TaF 5 , TaBr 5 , TaI 5 , TiCl 4 , TiF 4 , TiBr 4 , TiI 4  and WF 6 . The carbonyl compound gas may be W(CO) 6 .  
      In the film-forming method according to the present invention, the first process gas and the second process gas may be supplied to the process chamber through a shower head part provided in the process chamber. The plasma exciting means may include the shower head part to which a high-frequency power is applied to excite plasma.  
      According to the present invention, when forming a film on a substrate to be processed using a plurality of gases, the plurality of gases are prevented from being mixed with each other in a gas supply passage, which suppresses generation of particles in the gas supply passage and provides a stable and clean film formation.  
      Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an illustration showing a film-forming apparatus that performs a film-forming method according to a first embodiment of the present invention;  
       FIG. 2  is an illustrative cross-sectional view of a shower head part shown in  FIG. 1 ;  
       FIG. 3  is a flowchart of an example of the film-forming method according to the first embodiment of the present invention; and  
       FIGS. 4A through 4D  are graphs showing result of analysis on films formed by the film-forming method according to the first embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      A description will now be given of a film-forming method according to a first embodiment of the present invention.  
       FIG. 1  is an illustration of a film-forming apparatus which performs the film-forming method according to the first embodiment of the present invention.  
      The film-forming apparatus shown in  FIG. 1  comprises a process chamber  11 , which can accommodate an object W to be processed therein. A first process gas and a second process gas is supplied into a process space  11 A formed inside the process chamber  11  through a gas line  200  and a gas line  100 , respectively.  
      The process gases are supplied to the process space  11 A alternately on an individual kind basis so as to form a film at a level close to an atomic layer or a molecular layer through adsorption of the process gases onto a surface of the object W to be processed. Such a process is repeated so as to form a film having a predetermined thickness on the object W to be processed. This film-forming method is generally referred to as the Atomic Layer Deposition (ALD) method. The film formed by the ALD method has less impurities and high-quality even though a film-forming temperature is low. Additionally, the ALD method provides a good coverage when forming a micro pattern.  
      According to the film-forming method according to the present embodiment, a reverse-flow preventing gas is supplied to the process space  11 A through the gas line  200  or the gas line  100  during film formation, which prevents the first gas and the second gas from being mixed with each other in the gas supply path. Thereby, generation of particles is suppressed and a clean and stabel film can be formed. A specific method of supplying a reverse flow preventing gas will be mentioned later.  
      A description will be given of the film-forming apparatus in detail. The film-forming apparatus  10  shown in  FIG. 1  has the process chamber  11 , which is made of, for example, aluminum, aluminum with an anodized surface, or stainless steal. A substrate support table  12  is located inside the process chamber  11  by being supported by a substrate support table support part  12   a . The substrate support table  12  has a generally circular shape and is made of, for example, hastelloy. A semiconductor substrate W to be processed is placed on the substrate support table  12 . A heater (not shown in the figure) is incorporated in the substrate support table  12  so as to heat the substrate W to be processed.  
      The process space  11 A inside the process chamber  11  is subjected to evacuation by evacuating means (not shown in the figure) connected to an exhaust port  15  so that the process area  11 A is set in a depressurized state. Additionally, the substrate W to be processed is carried in or taken out of the process chamber  11  through a gate valve (not shown in the figure) provided to the process chamber.  
      Moreover, a generally cylindrical shower head part  13  made of, for example, aluminum is located so as to face the substrate support table  12  in the process chamber  11 . An insulator  6  made of, for example, quartz, SiN, AlN, etc., is provided to the sidewall surface of the shower head part  13  and between the shower head part  13  and an upper wall of the process chamber  11 .  
      Moreover, an opening is provided in the upper wall of the process chamber  11  above the shower head part  13 , and an insulator  14  made of an insulating material is inserted into the opening. A conductor line  17   a  connected to a high-frequency power supply  17  is inserted into the insulator  14 . The conductor line  17   a  is connected to the shower head part  13  so that a high-frequency power is applied to the shower head part  13  through the conductor line  17   a.    
      Moreover, the gas line  200 , which supplies the first process gas to the process space  11 A, and the gas line  100 , which supplies the second process gas to the process space  11 A, are connected to the shower head part  13  so that the first and second process gases are supplied to the process space  11 A through the shower head part  13 . Moreover, insulators  200   a  and  100   a  are inserted into the gas lines  200  and  100 , respectively, so that the gas lines area isolated from the high-frequency power.  
       FIG. 2  is an illustrative cross-sectional view of the shower head part  13 . In  FIG. 2 , parts that are the same as the parts shown in  FIG. 1  are given the same reference numerals, and descriptions thereof will be omitted. The shower head part  13  comprises a shower head body  13 A and a shower plate  13 B attached to the shower head body  13 A. The shower had body  13 A includes a gas flow passage  200 G for the first process gas and a gas flow passage  100 G for the second process gas. Formed in the shower plate  13 B are a plurality of gas holes  13 E including gas holes  13   c  and  13   d.    
      The gas flow passage  200 G connected to the gas line  200  is further connected to the gas holes  13   d  of the shower plate  13 B. Accordingly, the first process gas is supplied to the process space  11 A through the first gas supply path, which comprises the gas line  200 , the gas flow passage  200 G and the gas holes  13   d . On the other hand, the gas flow passage  100 G connected to the gas line  100  is further connected to the gas holes  13   c  of the shower plate  13 B. Accordingly, the first process gas is supplied to the process space  11 A through the second gas supply path, which comprises the gas line  100 , the gas flow passage  100 G and the gas holes  13   c.    
      Thus, the passages of the first process gas and the second process gas are formed independently in the shower head part  13 , and the first process gas and the second process gas are mixed with each other in the process space  11 A. That is, the shower head part  13  forms a so-called post-mix type shower head.  
      Moreover, a first process gas supply part  200 A, which supplies the first process gas to the gas line  200 , is connected to the gas line  200  via a gas line  204 . Additionally, a reverse flow preventing gas supply part  200 B, which supplies a reverse flow preventing gas to the gas line  200 , is connected to the gas line  200  via a gas line  201 .  
      Similarly, a second first process gas supply part  10 A, which supplies the second process gas to the gas line  100 , and a reverse flow preventing gas supply part  100 B, which supplies a reverse flow preventing gas to the gas line  100 , are connected to the gas line  100 .  
      First, a description will be given of the first process gas supply part  200 A. The gas line  204  is connected with a gas line  205  provided with a valve  205   a  and a gas line  210  provided with a valve  210   a . That is, the gas line  204  has a structure in which the two kinds of process gases, which are supplied through the gas line  205  and the gas line  210 , are used by switching by opening and closing of the valves.  
      A vaporizer  205 A, which evaporates a liquid material, is connected to the gas line  205  through the valve  205   a . The vaporizer  205 A vaporizes the liquid material supplied from a line  206  so as to change into the first process gas, and supplies the thus produced first process gas to the gas line  200  through the gas line  204  together with a carrier gas, such as, for example, Ar or the like, supplied from a line  209 .  
      The line  206  supplying the liquid material to the vaporizer  205 A has a liquid mass-flow controller  206 A and valves  206   a ,  206   b  ad  206   c , and is connected to a material container  207  storing a material  207 A therein. a material containing metal such as, for example, Ta(NC(CH 3 ) 2 C 2 H 5 )(N(CH 3 ) 2 ) 3 , is stored in the material container  207 A. The material is pressurized by a gas such as, for example, He or the like, supplied through a gas line  208  so as to be supplied to the vaporizer  205 A.  
      Moreover, the gas line  210  is connected with a mass-flow controller  211 A, and a line  211  provided with valves  211   a ,  211   b  and  211   s . The line  211  is connected to material container  213 , which stores a material  213 A such as, for example, TaCl 5  or the like. Additionally, the gas line  210  is connected with a mass-flow controller  212 A and a gas line  212 , which is provided with valves  212   a  and  212   b  and introduces a carrier gas such as, for example, Ar or the like. The first process gas is supplied to the process space  11 A together with a carrier gas such as Ar or the like from the gas line through the gas line  200  and further the shower head part  13 .  
      Moreover, the reverse flow preventing gas supply part  200 B includes a gas line  202  connected to a H 2  gas supply source and a gas line  203  connected to an Ar gas supply source. The gas line  202  is provided with a mass-flow controller  202 A and valves  202   a  and  202   b  and the gas line  203  is provided with a mass-flow controller  203 A and valves  203   a  and  203   b  so that the reverse flow preventing gas can be selected and a flow of the reverse flow preventing gas can be controlled.  
      On the other hand, the second process gas supply part  100 A connected to the gas line  100  comprises a gas line connected with a H 2  gas supply source and a gas line connected with a NH3 gas supply source. The gas line  101  is connected with a mass-flow controller  102 A and valves  102   a  and  102   b  so that the second process gas supplied to the gas line  100  is selected and a flow of the second process gas is controlled.  
      Moreover, the reverse flow preventing gas supply part  100 B connected to the gas line  100  comprises a mass-flow controller  103 A connected with an Ar gas supply source and a gas line  103  provided with a mass-flow controller  103 A and valves  103   a  and  103   b  so that a flow of the reverse flow preventing gas supplied to the gas line  100  is controlled.  
      When forming a film containing metal on the substrate W to be processed placed on the substrate support table  12  using the above-mentioned film-forming apparatus  10 , the film-forming apparatus is controlled as follows.  
      First, the first process gas containing metal is supplied from the first process gas supply part  200 A to the process space  11 A through the gas line  200  and the shower head part  13 . After the first process gas is adsorbed onto the substrate to be processed, the first process gas remaining in the process space is evacuated through the exhaust port  15 . In this case, the process space  11 A may be purged by a purge gas.  
      Then, the second process gas, which reduces the first gas, is supplied to the process space  11 A from the second process gas supply part  101 A through the gas line  100  and the shower head part  13 . Additionally, in this case, it is preferable to apply a high-frequency to the shower head part  13  by the high-frequency power supply  17  so as to excite plasma of the second process gas in the process space  11 A, which progresses dissociation of the second process gas and promotes the reduction of the first process gas.  
      Then, the second process gas remaining in the process space  11 A is evacuated through the exhaust port  15 . In this case, the process space  11 A may be purged using a purge gas.  
      Repeating the above-mentioned process to supply the first process gas to the process space and evacuate the first gas and further supply the second gas to the process space and evacuate the second gas, a film containing metal and having a predetermined thickness, a film containing metal nitride or the like can be formed on the substrate W to be processed.  
      The film formed by the ALD method has few impurities therein, and has an advantage of a good film quality.  
      However, conventionally, there is a problem in that the first process gas and the second process gas, that is, the gas containing metal and a reducing gas, are mixed with each other in a space other than the process space  11 A, which produces a generation source of particles. Such particles may cause deterioration of a yield rate in a semiconductor manufacturing process using the film-forming process.  
      For example, in the process of supplying the first process gas to the process space  11 A, the first process gas supplied to the process space  11 A may diffuse or enter the second gas supply passage for supplying the second process gas, such as the gas holes  13   d , the gas flow passage  100 G and the gal line  100 . Thereby, the first process gas and the second process gas react with each other in the second process gas supply passage, which causes generation of particles. Similarly, in the process of supplying the second process gas to the process space  11 A, the second process gas supplied to the process space  11 A may diffuse or enter the first gas supply passage for supplying the first process gas, such as the gas holes  13   c , the gas flow passage  200 G and the gal line  200  shown in  FIG. 2 . Thereby, the first process gas and the second process gas react with each other in the first process gas supply passage, which causes generation of particles.  
      Thus, in the film-forming method according to the present invention, the reverse flow preventing gas is supplied to the process space  11 A through the second supply passage in the process of supplying the first process gas to the process space  11 A, and the reverse flow preventing gas is supplied to the process space  11 A through the first supply passage in the process of supplying the second process gas to the process space  11 A. Accordingly, the second process gas is prevented from being diffused or entering into the first supply passage and generation of particles due to reaction of the first process gas and the second process gas in the first gas supply passage can be suppressed. Similarly, the first process gas is prevented from being diffused or entering into the second supply passage and generation of particles due to reaction of the first process gas and the second process gas in the second gas supply passage can be suppressed.  
      Moreover, especially when the second process gas is supplied to the process space  11 A and plasma excitation is performed, it is possible that a problem occurs in the film-forming process depending on a kind of the reverse flow preventing gas. For example, there is a problem in that, when a gas having a relatively large mass (large atomic number) such as Ar or the like is uses as the reverse flow preventing gas, ions generated by ionization of the reverse flow preventing gas generate sputtering of the shower head part  13  and the inner wall of the process camber  11  in the process space  11 A, which causes scatter of particles or pollution sources. For example, the material, such as Al or other metals, forming the inner wall of the shower head part  13  and the process chamber  11  are sputtered and incorporated into the film on the substrate to be processed, which produces pollution sources.  
      Thus, in the present embodiment, when the second process gas is supplied, a gas having a small mass (small atomic number) such as, for example, H 2  gas, is uses as the reverse flow preventing gas supplied from the first gas supply passage so as to reduce an amount of sputtering portion of the shower head part, which suppresses scattering of particles and pollution substances and consequently suppressing mixture of impurities in the film. The reverse flow preventing gas is not limited to H2, and it is possible to use other gas having a small mass such as, for example, He gas.  
      Furthermore, it is further preferable if the reverse flow preventing gas supplied from the first gas supply passage is the same as the second process gas supplied from the second gas supply passage. In such a case, if H 2  gas is uses as the second process gas, that is, the reducing gas which reduces the first process gas, it is preferable to use H 2  gas as the reverse flow preventing gas supplied from the first gas supply passage.  
      In this case, substantially only H 2  gas is supplied to the process space  11 A from the first gas supply passage and the second gas supply passage. Thus, there is no impurity entering into the film from the reverse flow preventing gas. Further, an amount of sputtering of the shower head part is reduced, which reduces an amount of scattering pollution substances. Thus, an amount of pollution substances taken into the film is reduced, which results in a good quality of the film formed.  
      A description will now be given, with reference to a flowchart shown in  FIG. 3 , of an example of film formation using the film-forming apparatus  10 .  
       FIG. 3  is a flowchart showing a film-forming method according to the present embodiment.  
      First, the substrate W to be processed is carried into the film-forming apparatus  10  in step S 1 .  
      Then, in step S 2 , the substrate W to be processed is placed on the substrate support table  12 .  
      In step S 3 , the temperature of the substrate W is raised by the heater incorporated in the substrate support table  12 .  
      Then, in step S 4 , the valves  206   a ,  206   b  and  206   c  are opened so as to supply the liquid material  207 A, which is a liquid of Ta (NC(CH 3 ) 2 C 2 H 5 )(N(CH 3 ) 2 ) 3 , from the material container  66  to the vaporizer  205 A through the line  206  while controlling a flow of the liquid material  207 A by the liquid mass-flow controller  206 A.  
      In the vaporizer  205 A, the first gas is produced by vaporizing the liquid material  207 A. The first process gas is supplied to the process space  11 A through the gas line  205 , the gas line  204  and the gas line  200  together with Ar, which is also supplied to the vaporizer  205 A through the gas line  209 .  
      In this step, the first process gas is supplied onto the substrate W to be processed, which results in adsorption of the first process gas onto the substrate W.  
      Additionally, in this step, the valve  103   a  and the valve  103   b  are opened so as to supply Ar gas, which serves as the reverse flow preventing gas, to the process space  11 A through the gas line  100  while controlling a flow of the reverse flow preventing gas. Thus, it can be suppressed that the first process gas diffuses or enters into the second gas supply passage and the first process gas and the second process gas react with each other in the second gas supply passage, which causes generation of particles.  
      Then, in step S 5 , the valves  206   a ,  206   b  and  206   c  are closed to stop the supply of the first process gas to the process space  11 A so as to discharge the first process gas, which is not adsorbed onto the substrate W and remaining in the process space  11 A, out of the process chamber  11  through the exhaust port  15 . In this case, the valves  203   a  and  203   b  and the valves  103   a  and  103   b  are opened so as to purge the process space  11 A by introducing Ar gas as a purge gas through the gas line  200  and the gas line  100 . In this case, the remaining first process gas can be rapidly discharged from the process space  11 A. After the purge of a predetermined period is completed, the valves  203   a  and  203   b  and the valves  103   a  and  103   b  are closed.  
      Then, in step S 6 , the valves  101   a  and  101   b  are opened so as to introduce H2 gas into the process space  11 A through the gas line  100  while controlling a flow of the H2 gas by the mass-flow controller  101 A. Additionally, a high-frequency or radio-frequency power (RF) is applied from the high-frequency power supply  17  to the shower head part  13  so as to perform plasma excitation in the process space  11 A. In this case, H 2  gas in the process space  11 A is dissociated and changed into H+/H* (hydrogen ions and hydrogen radials). Then, the first process gas (Ta 3  (NC(CH 3 ) 2 C 2 H 5 )(N(CH 3 ) 2 )) reacts with H+/H*, thereby producing Ta(C)N. In this case, the second process gas may be supplied for a predetermined time period so as to stabilize the flow of the second gas and to increase the pressure in the process space  11 A.  
      In this step, the valve  202   a  and the valve  202   b  are opened so as to supply the H 2  gas, which serves as the reverse flow preventing gas, to the process space  11 A through the gas line  200  while controlling a flow of the Hs gas by the mass-flow controller  202 A. Accordingly, it can be suppressed that the second process gas diffuses or enters into the first gas supply passage and the first process gas and the second process gas react with each other in the first gas supply passage, which causes generation of particles.  
      Moreover, in this case, since the reverse flow preventing gas supplied from the first gas supply passage is the same as the second process gas supplied from the second gas supply passage, substantially only H 2  gas is supplied from the first gas supply passage and the second gas supply passage. Thus, there is no impurity entering the film from the reverse flow preventing gas during the film-forming process. Additionally, the excited plasma is stabilized. Further, since the reverse flow preventing gas is the H 2  gas having a small mass, an amount of sputtering of the shower head part is reduced, which reduces an amount of scattered pollution substances. Thereby, an amount of pollution substances taken into the film is reduced, which achieves formation of a good quality film.  
      Then, in step S 7 , the valves  206   a ,  206   b  and  206   c  are closed to stop the supply of the second process gas to the process space  11 A so as to discharge the second process has, which is not reacted with the first process gas on the substrate W and remaining in the process space  11 A, out of the process chamber through the exhaust port  15 . In this case, the valves  203   a  and  203   b  and the valves  103   a  and  103   b  are opened so as to purge the process space by introducing Ar gas as a purge gas from the gas line  2000  and gas line  100 . In this case, the second process gas can be rapidly discharged from the process space  11 A. After the purge of a predetermined time period is completed, the valves  101   a  and  101   b  and the valves  202   a  and  202   b  are closed.  
      Then, in step S 8 , it is determined whether or not the process of step S 4  through step S 7  has been repeated for a predetermined number of timed. If not, the routine returns to step S 4  so as to repeat the process for the predetermined time. If the process has been repeated for the predetermined time so as to form a film having a desired thickness, the routine proceeds to step S 9 .  
      Then, in step S 9 , the substrate W to be processed is separated from the substrate support table  12 . In step S 10 , the substrate W is carried out of the process chamber  11 .  
      As mentioned above, a film containing metal such as, for example, Ta(C)N film is formed on the substrate W by the film-forming method according to the present embodiment. It should be noted that the Ta(C)N film is a film containing at least Ta, C and N therein, and coupling state and content of those elements are not limited and impurities may be contained in the film. Additionally, the content of the elements may be changed by changing film-forming conditions or gases to be used.  
      Moreover, since the film containing metal formed by the film-forming method according to the present embodiment has less impurities and is a high-quality film and a good coverage characteristic can be achieved when forming a micro pattern, it is suitable to use the film-forming method to form a diffusion preventing film (a barrier film or an adhesion film) of Cu wiring in a high-performance semiconductor device having a micro wiring patter.  
      Moreover, the film which can be formed by the film-forming method according to the present embodiment is not limited to a film containing Ta, such as Ta(C)N film. That is, a film containing metal such as, for example, Ti, W, etc., may be formed, and an effect the same as the effect of formation of the film containing Ta can be provided.  
      For example, it is possible to form a Ta film, a TaN film, a Ta(C) N film, a Ti film, a TiN film, a Ti(C) N film, a W film, a WN film, a W(C) N film, etc., by the film-forming method according to the present embodiment. It should be noted that the Ta(C)N film is a film containing at least Ta, C and N therein, and a coupled state and content of each element are not limited. Similarly, the Ti(C)N film and the W(C)N film are films containing at least Ti, C and N and W, C and N, respectively therein, and a coupled state and content of each element are not limited. Additionally, also in a case to forming the TaN film, the TiN film and the WN film, especially in a case where a gas containing C is used as the first process gas, C may remain in the film. Additionally, the composition and the content of each element may be changed as needed.  
      For example, in the film-forming method shown in  FIG. 3 , the material  207 A may be replaced by the material  213 A. That is, the same process can be performed by changing the first process gas from Ta(NC(CH 3 ) 2 C 2 H 5 ) (N(CH 3 ) 2 ) 3  to TaCl 5  so that the first process gas is supplied to the shower head part  13  through the gas line  210 , the gas line  204  and the gas line  200 . In this case, a Ta film is formed on the substrate W to be processed.  
      Moreover, in the film-forming method shown in  FIG. 3 , the same process can be performed by changing the second process gas from H 2  gas to NH 3  gas so that the second process gas is supplied to the shower head part  13  through the gas line  102  and the gas line  100 . In this case, a film mainly containing Ta and N (TaN film) is formed on the substrate to be processed. In this case, it is not always necessary to use the plasma excited second process gas, and, for example, Ta (NC(CH3)2C2H5) (N(CH3) 2)3 adsorbed onto the substrate to be processed can be reduced by using NH3 which is not plasma-excited.  
      Moreover, the first process gas is not limited to the above-mentioned example, and other various kinds of process gases may be used. For example, one of an amide compound gas, a halogen compound gas and carbonyl compound gas may be used as the first process gas.  
      For example, as for the amide compound gas, a gas selected from a group consisting of Ta(NC(CH 3 ) 2 (C 2 H 5 )(N(CH 3 ) 2 ) 3 , Ta[N(C 2 H 5 CH 3 )] 5 , Ta[N(CH 3 ) 2 ] 5 , Ta(NC(CH 3 ) 3 (N(C 2 H 5 ) 2 ) 3 , Ta(NC(CH 3 ) 3 (N(CH 3 ) 2 ) 3 , Ta(NC 2 H 5 )(N(C 2 H 5 ) 2 ) 3 , Ta(N(C 2 H 5 ) 2 (N(C 2 H 5 ) 2 ) 3 , Ti[N(C 2 H 5 CH 3 )] 4 , Ti[N(CH 3 ) 2 ] 4  and Ti[N(C 2 H 5 ) 2 ] 4  can be used.  
      Moreover, for example, as for the halogen compound, a gas selected from a group consisting of TaF 5 , TaBr 5 , TaI 5 , TiCl 4 , TiF 4 , TiBr 4 , TiI 4  and WF 6  can be used.  
      Further, as for the carbonyl gas, W(CO) 6  can be used.  
      The above-mentioned compounds for the first process gas may be a solid or a liquid at normal temperature, or may be a gas. If it is a liquid, it is vaporized by heating or vaporized using a vaporizer so a to produce a gas. If it is a solid, it can be sublimated by heating so as to produce a gas. Additionally, a solid material may be dissolved in a solvent and the solvent can be vaporized to produce the first process gas.  
      For example, although Ta (NC(CH3)2C2H5) (N(CH3) 2)3 explained as an example of the material  207 A in the present embodiment is a solid at a normal temperature, it can be treated as a liquid at a normal temperature by dissolving in a solvent containing solution of Hexane. Such a liquid can be vaporized by a vaporizer such as shown in  FIG. 1  so as to produce the first process gas. It should be noted that a heater (not shown in the figure) is attached to the material container  207  of the film-forming apparatus  10  shown in  FIG. 1  so that a solid material can be liquefied by heating.  
       FIGS. 4A through 4D  show results of analysis of films formed by the film-forming method shown in  FIG. 3  using the film-forming apparatus shown in  FIG. 1 , the analysis being made by an X-ray diffraction apparatus (XRD).  FIG. 4B  shows a result of analysis by an XRD in a case where a Ta(C)N film is formed on the substrate to be processed using Ta(NC(CH 3 ) 2 C 2 H 5 ) (N(CH 3 ) 2 ) 3  as the first process gas and H2 as the second process gas.  FIG. 4B  shows a result of analysis by an XRD in a case where the same gases as the case of  FIG. 4A  are used and 0.1 mol/l solution of Hexane is used as a solvent for dissolving a solid of Ta(NC(CH 3 ) 2 C 2 H 5 ) (N(CH 3 ) 2 ) 3 .  FIG. 4C  shows a result of analysis by an XRD in a case where a TaN film is formed on the substrate to be processed using Ta(NC(CH 3 ) 2 C 2 H 5 ) (N(CH 3 ) 2 ) 3  as the first process gas and NH 3  as the second process gas.  FIG. 4D  shows a result of analysis by an XRD in a case where a Ta film is formed on the substrate to be processed using TaCl 5  as the first process gas and H 2  as the second process gas.  
      Referring to  FIGS. 4A through 4D , for example, Ta—N bond and Ta—C bond were observed in the case of  FIG. 4A , and the same bonds were observed in the case of  FIG. 4B . Additionally, Ta—N bond was observed in the case of  FIG. 4C , and α-Ta was observed in the case of  FIG. 4D .  
      Additionally, there was no remarkable impurity or defect observed in the film. Thus, it was confirmed that a good and stable film formation was performed.  
      According to the present embodiment, when forming a film on a substrate to be processed using a plurality of gases, the plurality of gases are prevented from being mixed with each other in a gas supply passage, which suppresses generation of particles in the gas supply passage and provides a stable and clean film formation.  
      The present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope of the present invention.  
      The present application is based on Japanese priority application No. 2004-199678 filed Jul. 6, 2004, the entire contents of which are hereby incorporated herein by reference.