Patent Publication Number: US-2023148162-A1

Title: Film-forming method

Description:
TECHNICAL FIELD 
     The present disclosure relates to a film forming method. 
     BACKGROUND 
     Patent Document 1 discloses a technique for selectively forming a target film on a specific region of a substrate without using photolithography. Specifically, a technique is disclosed in which a self-assembled monolayer (SAM) that inhibits formation of a target film is formed in a partial region of the substrate and the target film is formed in the remaining region of the substrate. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-501902 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     The present disclosure provides a technique capable of controlling a shape of an SAM. 
     Means for Solving Problem 
     According to an aspect of the present disclosure, there is provided a method of forming a target film on a substrate, which includes preparing a substrate including a layer of a first conductive material formed on a surface of a first region, and a layer of an insulating material formed on a surface of a second region; forming carbon nanotubes on a surface of the layer of the first conductive material; and supplying a raw material gas for a self-assembled film to form a self-assembled film on a region of the surface of the layer of the first conductive material in which the carbon nanotubes have not been formed. 
     Effect of the Invention 
     According to an aspect, it is possible to control a shape of an SAM. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a flowchart illustrating a film forming method according to a first embodiment. 
         FIG.  2 A  is a cross-sectional view illustrating an example of a state of a substrate in each step illustrated in  FIG.  1   . 
         FIG.  2 B  is a cross-sectional view illustrating an example of a state of the substrate in each step illustrated in  FIG.  1   . 
         FIG.  2 C  is a cross-sectional view illustrating an example of a state of the substrate in each step illustrated in  FIG.  1   . 
         FIG.  2 D  is a cross-sectional view illustrating an example of a state of the substrate in each step illustrated in  FIG.  1   . 
         FIG.  2 E  is a cross-sectional view illustrating an example of a state of the substrate in each step illustrated in  FIG.  1   . 
         FIG.  2 F  is a cross-sectional view illustrating an example of a state of the substrate in each step illustrated in  FIG.  1   . 
         FIG.  3    is a flowchart illustrating a film formation method according to a second embodiment. 
         FIG.  4 A  is a cross-sectional view illustrating an example of a state of a substrate in each step illustrated in  FIG.  3   . 
         FIG.  4 B  is a cross-sectional view illustrating an example of a state of the substrate in each step illustrated in  FIG.  3   . 
         FIG.  4 C  is a cross-sectional view illustrating an example of a state of the substrate in each step illustrated in  FIG.  3   . 
         FIG.  4 D  is a cross-sectional view illustrating an example of a state of the substrate in each step illustrated in  FIG.  3   . 
         FIG.  4 E  is a cross-sectional view illustrating an example of a state of the substrate in each step illustrated in  FIG.  3   . 
         FIG.  5    is a schematic view illustrating an example of a film forming system for executing a film forming method according to an embodiment. 
         FIG.  6    is a cross-sectional view illustrating an example of a processing apparatus that is capable of being used as a film forming apparatus and an SAM forming apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments for executing the present disclosure will be described with reference to drawings. In the specification and figures, constituent elements that are substantially the same in configuration will be denoted by the same reference numerals, and redundant descriptions may be omitted. Hereinbelow, a description will be made using a vertical direction or relationship in the figures, but it does not represent a universal vertical direction or relationship. 
     First Embodiment 
       FIG.  1    is a flowchart illustrating a film forming method according to a first embodiment.  FIGS.  2 A to  2 F  are cross-sectional views illustrating examples of the states of a substrate in respective steps illustrated in  FIG.  1   .  FIGS.  2 A to  2 F  illustrate states of a substrate  10  corresponding to respective steps S 101  to S 106  illustrated in  FIG.  1   . 
     As illustrated in  FIG.  2 A , a film forming method includes step S 101  of preparing the substrate  10 . Preparing the substrate  10  includes, for example, loading the substrate  10  into, for example, a processing container (chamber) of a film forming apparatus. The substrate  10  includes a conductive film  11 , a natural oxide film  11 A, an insulating film  12 , and a base substrate  15 . 
     The substrate  10  has a first region A 1  and a second region A 2 . Here, as an example, the first region A 1  and the second region A 2  are adjacent to each other in a plan view. The conductive film  11  is provided on the top surface side of the base substrate  15  in the first region A 1 , and the insulating film  12  is provided on the top surface side of the base substrate  15  in the second region A 2 . The natural oxide film  11 A is provided on the top surface of the conductive film  11  in the first region A 1 . In  FIG.  2 A , the natural oxide film  11 A and the insulating film  12  are exposed on the surface of the substrate  10 . 
     The number of first regions A 1  is one in  FIG.  2 A , but may be two or more. For example, two first regions A 1  may be arranged with a second region A 2  interposed therebetween. Similarly, the number of second regions A 2  is one in  FIG.  2 A , but may be two or more. For example, two second regions A 2  may be arranged with a first region A 1  interposed therebetween. 
     In addition, only the first region A 1  and the second region A 2  are present in  FIG.  2 A , but a third region may be further present. The third region is a region in which a layer made of a material different from those of the conductive film  11  in the first region A 1  and the insulating film  12  in the second region A 2  is exposed. The third region may be arranged between the first region A 1  and the second region A 2 , or may be arranged outside the first region A 1  and the second region A 2 . 
     The conductive film  11  is an example of a layer of the first conductive material. The first conductive material is a metal such as copper (Cu), cobalt (Co), or ruthenium (Ru). The surface of such a metal naturally oxidizes in the atmosphere over time. The oxide is the natural oxide film  11 A. The natural oxide film  11 A is removable through a reduction process. 
     Here, as an example, a mode in which the conductive film  11  is copper (Cu) and the natural oxide film  11 A is a copper oxide formed through natural oxidation will be described. The copper oxide as the natural oxide film  11 A may include CuO and Cu 2 O. 
     The insulating film  12  is an example of a layer of an insulating material, and may be an insulating film made of a so-called low-k material having a low dielectric constant. The insulating material of the insulating film  12  is, for example, an insulating material containing silicon (Si), such as silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or silicon oxycarbonitride. Hereinafter, silicon oxide is also referred to as SiO regardless of the composition ratio of oxygen and silicon. Similarly, silicon nitride is also referred to as SiN, silicon oxynitride is also referred to as SiON, silicon carbide is also referred to as SiC, and silicon oxycarbonitride is also referred to as SiOCN. The insulating film  12  is a SiO film in this embodiment. 
     The base substrate  15  is a semiconductor substrate such as a silicon wafer. The substrate  10  may further include, between the base substrate  15  and the conductive film  11 , a base film formed of a material different from those of the base substrate  15  and the conductive film  11 . Similarly, the substrate  10  may further include, between the base substrate  15  and the insulating film  12 , a base film formed of a material different from those of the base substrate  15  and the insulating film  12 . 
     Such a base film may be, for example, a SiN layer or the like. The SiN layer or the like may be, for example, an etching stop layer that stops etching. 
     The film forming method includes step S 102  of manufacturing the substrate  10  as illustrated in  FIG.  2 B  by reducing the natural oxide film  11 A (see  FIG.  2 A ). In order to reduce the natural oxide film  11 A, for example, flow rates of hydrogen (H 2 ) and argon (Ar) in the processing container of the film forming apparatus are set to 100 sccm and 2,500 sccm, respectively, and an internal pressure of the processing container is set to 1 torr to 10 torr (about 133.32 Pa to about 1,333.22 Pa). Then, a susceptor is heated such that the temperature of the substrate  10  is 150 degrees C. to 200 degrees C. under a hydrogen atmosphere in which hydrogen is less than 0.5% of an atmospheric gas within the processing container. 
     Through step S 102 , a copper oxide as the natural oxide film  11 A is reduced to Cu and removed. As a result, as illustrated in  FIG.  2 B , the substrate  10  including the conductive film  11 , the insulating film  12 , and the base substrate  15  is obtained. Cu as the conductive film  11  is exposed on the surface of the first region A 1  of the substrate  10 . The reduction process on the natural oxide film  11 A is not limited to a dry process, but may be a wet process. As an example, step S 102  may be performed in the same processing container in which step S 101  is performed. 
     The film forming method includes step S 103  of forming catalyst metal fine particles  13 A on the surface of the conductive film  11  as illustrated in  FIG.  2 C . The catalyst metal fine particles  13 A are an example of catalyst metal fine particles of a second conductive material, and the second conductive material is, for example, a transition metal such as cobalt (Co) or nickel (Ni), or an alloy containing the transition metal. The catalyst metal fine particles  13 A later cause a catalytic action in forming carbon nano tubes (CNTs) and become nuclei or seeds in the growth of CNTs. The size of the catalyst metal fine particles  13 A is, for example, 1 nm to 5 nm. In the present embodiment, a mode in which the catalyst metal fine particles  13 A are Co fine particles will be described. 
     The catalyst metal fine particles  13 A may be formed, for example, on the surface of the conductive film  11  as follows. 
     First, a Co thin film is formed on the surface of the conductive film  11  through a thermal chemical vapor deposition (CVD) method. The internal pressure of the processing container of the film forming apparatus may be set to 1 Torr to 10 Torr (about 133.32 Pa to about 1,333.22 Pa), the susceptor may be heated such that the substrate temperature becomes 300 degrees C., and cobalt carbonyl (Co 2 (CO) 8 ) gas vaporized by preheating with a gas supply mechanism may be supplied into the processing container together with a diluting gas (e.g., Ar gas or N 2  gas) to form a Co thin film on the surface of the conductive film  11 . The substrate temperature in this process may be 300 degrees C. or lower at which Co-agglutination does not occur. The Co thin film may be formed by a sputtering method, a vapor deposition method, or the like, without being limited to the thermal CVD method. 
     Subsequently, oxygen plasma process is performed on the Co thin film by heating the substrate  10  and generating microwave plasma of an oxygen (O 2 ) gas and an argon (Ar) gas. When the oxygen plasma process is performed in this way, organic substances or the like adhering to the surface of the Co thin film can be removed so that the surface of the Co thin film can be cleaned. As a result, migration due to heating is likely to occur on the surface of the Co thin film, and Co-agglomeration occurs so that Co is turned into fine particles. In this way, island-shaped catalyst metal fine particles  13 A may be formed on the surface of the conductive film  11 . 
     As process conditions for the oxygen plasma process, for example, the internal pressure of the processing container of the film forming apparatus may be set to 67 Pa to 533 Pa, the susceptor may be heated such that the temperature of the substrate 10 becomes 300 degrees C. to 600 degrees C., and the flow rates of the O 2  gas and the Ar gas may be set to 50 sccm to 200 sccm, and 300 sccm to 600 sccm, respectively, and the microwave output may be set to 250 W to 2,000 W. In the oxygen plasma process, an oxygen-containing gas such as H 2 O, O, O 3 , or N 2 O may be used instead of the O 2  gas. 
     After the oxygen plasma process, an activation process is performed. In the activation process, microwave plasma of a hydrogen (H 2 ) gas and an Ar gas is generated to reduce and activate the surfaces of the catalyst metal fine particles  13 A. By the activation process, the oxide films on the surfaces of the catalyst metal fine particles  13 A formed by the oxygen plasma process are removed, and the catalyst metal fine particles  13 A can be further increased in density while maintaining the state of the fine particles. 
     As process conditions for the activation process, for example, the internal pressure of the processing container of the film forming apparatus may be set to 67 Pa to 533 Pa, the susceptor may be heated such that the temperature of the substrate  10  becomes 300 degrees C. to 600 degrees C., and the flow rates of the H 2  gas and the Ar gas may be set to 100 sccm to 1,200 sccm, and 300 sccm to 600 sccm, respectively, and the microwave output may be set to 250 W to 2,000 W. In the activation process, a hydrogen-containing gas such as an ammonia (NH 3 ) gas may be used instead of the H 2  gas. 
     As illustrated in  FIG.  2 C , the catalyst metal fine particles  13 A are formed on the surface of the conductive film  11  in step S 103 , and thus the substrate  10  including the conductive film  11 , the insulating film  12 , the catalyst metal fine particles  13 A, and the base substrate  15  is obtained. In  FIG.  2 C , the conductive film  11 , the catalyst metal fine particles  13 A, and the insulating film  12  are exposed on the surface of the substrate  10 . As an example, step S 103  may be performed in the same processing container in which step S 102  is performed. 
     As illustrated in  FIG.  2 D , the film forming method includes step S 104  of forming CNTs  13 B. The CNTs  13 B are formed on the catalyst metal fine particles  13 A and grows vertically on the surfaces of the substrate  10  and the conductive film  11  in the first region A 1 . The CNTs  13 B, together with the SAM formed later, inhibit the formation of a target film  14  to be described later. The CNTs  13 B are not formed in the second region A 2 . 
     The CNTs  13 B may be grown by decomposing a carbon-containing gas (carbon source gas) such as methane (CH 4 ), ethylene (C 2 H 4 ), ethane (C 2 H 6 ), or propylene (C 3 H 6 ) by plasma, and by using the catalytic action of the fine particles  13 A. In this way, the CNTs  13 B can be grown on the catalyst metal fine particles  13 A. The CNTs  13 B grow vertically on the surface of the conductive film  11  due to a vertical orientation. 
     Under process conditions for forming CNTs  13 B, film formation is, for example, as follows. Here, a mode in which the C 2 H 4  gas is used as the carbon source gas will be described. The CNTs  13 B may be grown by setting the internal pressure of the processing container of the film forming apparatus to 67 Pa to 533 Pa, heating the susceptor such that the temperature of the substrate  10  becomes 300 degrees C. to 600 degrees C., causing the C 2 H 4  gas, the H 2  gas, and the Ar gas to flow at 5 sccm to 150 sccm, 100 sccm to 1,200 sccm, and 300 sccm to 600 sccm, respectively, and setting the microwave output to 250 W to 2,000 W to generate microwave plasma. A hydrogen-containing gas such as an ammonia (NH 3 ) gas may be used instead of the H 2  gas. 
     The height of the CNTs  13 B is preferably higher than that of the target film  14  to be formed later. This is to suppress the infiltration of the target film  14  into the first region A 1 . The height of CNTs  13 B is, for example, about 10 nm to 25 nm. 
     As illustrated in  FIG.  2 D , the catalyst metal fine particles  13 A and the CNTs  13 B are formed on the surface of the conductive film  11  in step S 104 , and thus the substrate  10  including the conductive film  11 , the insulating film  12 , the catalyst metal fine particles  13 A, the CNTs  13 B, and the base substrate  15  is obtained. In  FIG.  2 D , the conductive film  11 , the catalyst metal fine particles  13 A, the CNTs  13 B, and the insulating film  12  are exposed on the surface of the substrate  10 . Since the catalyst metal fine particles  13 A are scattered on the surface of the conductive film  11 , there are gaps between the CNTs  13 B, and the conductive film  11  are exposed from the gaps. As an example, step S 104  may be performed in the same processing container in which step S 103  is performed. 
     As illustrated in  FIG.  2 E , the film forming method includes step S 105  of forming an SAM  13 B. The SAM  13 C is adsorbed on the surface of the conductive film  11  exposed from the gaps of the CNTs  13 B of the first region A 1 , and grows vertically on the surface of the conductive film  11  while being corrected in the vertical direction by the CNTs  13 B. The SAM  13 C cooperates with the CNTs  13 B to inhibit the formation of the target film  14  to be described later. The SAM  13 C is not formed in the second region A 2 . In general, when the SAM is formed at a high density, the SAM exhibits high orientation by virtue of the van der Waals force between molecules and tends to be oriented diagonally with respect to the surface of the film. In the present embodiment, the SAM  13 C grows vertically on the surface of the conductive film  11  by being corrected by the CNTs  13 B formed vertically on the surface of the conductive film  11 . 
     An organic compound for forming the SAM  13  may have any of fluorocarbon-based functional group (CFx) or alkyl-based functional group (CHx) as long as it is a thiol-based compound. For example, CH 3 (CH 2 )[x]CH 2 SH [x=1 to 18] and CF 3 (CF 2 )[x]CH 2 CH 2 SH [x=0 to 18] may be used. In addition, the fluorocarbon-based functional group (CF x ) includes fluorobenzenethiol. 
     For example, the flow rates of the gaseous thiol-based organic compound and argon (Ar) are set to 100 sccm and 1,500 sccm, respectively, the internal pressure of the processing container of the film forming apparatus is set to 1 torr to 10 torr (133.32 Pa to 1,333.22 Pa), and the susceptor is heated such that the temperature of the substrate 10 becomes 150 degrees C. to 200 degrees C. As an example, step S 105  may be performed in a processing container different from that in which step S 104  is performed. 
     The thiol-based organic compound described above is a compound in which electron exchange with a metal is likely to occur. Accordingly, the SAM  13 C has a property of being adsorbed on the surface of the conductive film  11  and being unlikely to be adsorbed on the surface of the insulating film  12  on which the exchange of electrons is unlikely to occur. Therefore, when film formation is performed while causing the thiol-based organic compound in the processing container, the SAM  13 C is selectively formed only on the surface of the conductive film  11 . The film thickness of the SAM  13 C (the height of molecules of SAM  13 C) is, for example, about 3 nm. 
     Therefore, through step S 105 , the SAM  13 A is formed on the surface of the conductive film  11 , and thus, as illustrated in  FIG.  2 E , the substrate  10  including the conductive film  11 , the catalyst metal fine particles  13 A, the CNTs  13 B, and the SAM  13 A formed in the first region A 1  and the insulating film  12  formed in the second region A 2  is obtained. Since the height of the CNTs  13 B is higher than that of the SAM  13 C, the CNTs  13 B protrudes from the top surface of the SAM  13 C. In  FIG.  2 E , the CNTs  13 B, the SAM  13 C, and the insulating film  12  are exposed on the surface of the substrate  10 . In step S 105 , the selectivity of the thiol-based organic compound for forming the SAM  13 C is used. 
     As illustrated in  FIG.  2 F , the film forming method includes step S 106  of forming a target film  14  selectively in the second region A 2  using the CNTs  13 B and the SAM  13 C. The target film  14  is formed of a material different from those of the CNTs  13 B and the SAM, for example, a metal, a metal compound, or a semiconductor. Since the SAM  13 C inhibits the formation of the target film  14 , the target film  14  is formed selectively in the second region A 2 . When a third region is present in addition to the first region A 1  and the second region A 2 , the target film  14  may or may not be formed in the third region. 
     Here, when the CNTs  13 B are terminated with an alkyl group or a fluoro group, it is considered that the CNTs  13 B also have a property of inhibiting the formation of the target film  14  like the SAM  13 C, and assists the SAM  13 C in inhibiting the formation of the target film  14 . In this case, the formation of the target film  14  on the first region A 1  may be inhibited using the CNTs  13 B and the SAM  13 C as a blocking layer. 
     The target film  14  is formed through, for example, a CVD method or an atomic layer deposition (ALD) method. The target film  14  is formed of, for example, an insulating material. The object film  14 , which is an insulating film, may be selectively laminated on the insulating film  12  that is originally present in the second region A 2 . 
     The target film  14  is formed of, for example, an insulating material containing silicon. The insulating material containing silicon is, for example, silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiON), or silicon carbide (SiC). 
     As described above, according to the present embodiment, the natural oxide film  11 A, which is present on the surface of the conductive film  11 , is removed through a reduction process, and then the catalyst metal fine particles  13 A made of Co are formed on the surface of the conductive film  11 . Then, the CNTs  13 B are grown vertically on the catalyst metal fine particles  13 A using Co as a catalyst metal. In addition, using the selectivity of the thiol-based organic compound for producing the SAM  13 C, the SAM  13 C is formed on the surface of the conductive film  11  in the gaps between the molecules of the CNT  13 B. 
     Since the CNTs  13 B grow vertically on the surface of the conductive film  11  due to the vertical orientation, the SAM  13 C adsorbed on the surface of the conductive film  11  through the gaps between the molecules of the CNT  13 B is corrected by the CNTs  13 B to grow in the vertical direction. In this way, by using the CNTs  13 B, the shape of the SAM  13 C can be controlled such that the SAM  13 C grows vertically. 
     Therefore, the side surface of the SAM  13 C (the side surface generated in the film thickness direction) at the boundary between the first region A 1  and the second region A 2  is vertical to the surface of the conductive film  11 . That is, the shape of the SAM  13 C can be controlled such that the boundary adjacent to the second region A 2  on which the target film  14  is formed has an upright shape. 
     Therefore, it is possible to provide a film forming method capable of controlling the shape of the SAM  13 C. The upright shape is not limited to the case in which the side surface of the SAM  13 C is strictly vertical to the surface of the conductive film  11 , but also includes a case in which the side surface of the SAM  13 C is deviated from the vertical due to a manufacturing error or the like. 
     In addition, the side surface of the target film  14 , which is formed adjacent to the side surface of the SAM  13 C, at the boundary between the first region A 1  and the second region A 2  is vertical to the surfaces of the conductive film  11  and the insulating film  12 . The fact that the target film  14  has a vertical side surface as described above is very effective in dealing with nanometer-level miniaturization in a semiconductor manufacturing process or the like after removing the CNTs  13 B and the SAM  13 C by etching. 
     Therefore, according to the film forming method according to the present embodiment, it is possible to deal with the nanometer-level miniaturization so that a highly productive semiconductor manufacturing process can be realized. 
     In the foregoing, the mode in which the CNTs  13 B are grown by generating microwave plasma has been described, but the present disclosure is not limited to the microwave plasma. The CNTs  13 B may be grown through thermal CVD or the like. 
     In addition, in the foregoing, the mode in which the processes of steps S 101  to S 104  are performed in the same processing container, and the process of forming the SAM  13 C in step S 105  and the process of forming the target film  14  in step S 106  are performed in different processing containers have been described. 
     However, steps S 101  and S 102  and steps S 103  and S 014  may be performed in separate processing containers, respectively. 
     In addition, the process of forming the CNTs  13 B in step S 104  may be performed in a processing container different from that for the processes in steps S 101  to S 103 . The processing container may be appropriately divided according to the conditions of the process for forming the CNT  13 B or the like. 
     Second Embodiment 
       FIG.  3    is a flowchart illustrating a film forming method according to a second embodiment.  FIGS.  4 A to  4 E  are cross-sectional views illustrating examples of states of a substrate in respective steps illustrated in  FIG.  3   .  FIGS.  4 A to  4 E  illustrate the states of a substrate  20  corresponding to respective steps S 201  to S 205  illustrated in  FIG.  3   . 
     As illustrated in  FIG.  4 A , the film forming method includes step S 201  of preparing the substrate  20 . The preparing the substrate  20  includes, for example, loading the substrate  20  into a processing container of, for example, a film forming apparatus. The substrate  20  includes a conductive film  21 , an antirust film  21 A, an insulating film  12 , and a base substrate  15 . 
     The substrate  20  has a structure in which the copper (Cu) conductive film  11  and the natural oxide film  11 A of the substrate  10  illustrated in  FIG.  2 A  are replaced with the cobalt (Co) conductive film  21  and the antirust film  21 A, respectively. 
     The substrate  20  has a first region A 1  and a second region A 2 . The antirust film  21 A is provided on one surface (the top surface in  FIG.  4 A ) of the conductive film  21 . That is, in  FIG.  4 D , the antirust film  21 A and the insulating film  12  are exposed on the surface of the substrate  20 . 
     The antirust film  21 A is, for example, a film which is coated with an antirust shield for protecting the surface of Cu as the conductive film  21  from oxidation and sulfidation (applied with an antirust coating). A specific example of the antirust film  21  is a film made of benzotriazole (BAT). The antirust film  21 A is formed on the surface of the conductive film  21 . 
     The film forming method includes step S 202  of removing the antirust film  21 A from the surface of the conductive film  21  as illustrated in  FIG.  4 B . For example, the antirust film  21 A may be removed by heating the susceptor such that the temperature of the substrate  20  becomes about 350 degrees C. in a hydrogen atmosphere with an atmospheric gas containing hydrogen (H 2 ) and argon (Ar). The antirust film  21 A is removed through heat treatment using hydrogen. 
     As illustrated in  FIG.  4 C , the film forming method includes step S 203  of forming CNTs  23 A. The CNTs  23 A are formed on the surface of the conductive film  21  and grows vertically on the surfaces of the substrate  10  and the conductive film  21  in the first region A 1 . The CNTs  23 A, together with an SAM  23 B formed later, inhibits the formation of a target film  14  to be described later. The CNTs  23 A are not formed in the second region A 2 . 
     In the present embodiment, since the conductive film  21  is a Co film having an action as a catalyst, the CNTs  23 A may be directly grown on the surface of the conductive film  21  by decomposing a carbon-containing gas (a carbon source gas) such as methane (CH 4 ), ethylene (C 2 H 4 ), ethane (C 2 H 6 ), or propylene (C 3 H 6 ) by plasma. The CNTs  23 A grow vertically on the surface of the conductive film  21  due to a vertical orientation. 
     In order to directly grow the CNTs  23 A on the surface of the conductive film  21 , the same process as that in step S 104  of the first embodiment may be performed. The height of the CNTs  23 A is preferably higher than that of the target film  14 , and is, for example, about 10 nm to 25 nm. 
     By step S 203 , as illustrated in  FIG.  4 C , the CNTs  23 A are formed on the surface of the conductive film  21 , and thus the substrate  20  including the conductive film  21 , the insulating film  12 , the CNTs  23 A, and the base substrate  15  is obtained. In  FIG.  4 C , the conductive film  21 , the CNTs  23 A, and the insulating film  12  are exposed on the surface of the substrate  20 . There are gaps between the CNTs  23 A, and the conductive film  21  is exposed from the gaps. As an example, step S 203  may be performed in the same processing container in which step S 202  is performed. 
     The film forming method includes step S 204  of forming the SAM  23 B as illustrated in  FIG.  4 D , and step S 205  of forming the target film  14  selectively in the second region A 2  using the CNTs  23 A and the SAM  23 B as illustrated in  FIG.  4 E . Steps S 204  and S 205  are the same as steps S 105  and S 106  of the first embodiment, respectively. 
     As described above, according to the present embodiment, the antirust film  21 A on the surface of the conductive film  21  is removed, and then the CNTs  23 A are grown vertically on the surface of the conductive film  21 . In addition, using the selectivity of the thiol-based organic compound for producing the SAM  28 B, the SAM  23 B is formed on the surface of the conductive film  21  in the gaps between the molecules of the CNT  13 B. 
     Since the CNTs  23 A grow vertically on the surface of the conductive film  21  due to the vertical orientation, the SAM  23 B adsorbed on the surface of the conductive film  21  through the gaps between the molecules of the CNT  23 A is corrected and grows in the vertical direction by the CNTs  23 A. In this way, by using the CNTs  23 A, the shape of the SAM  23 B can be controlled such that the SAM  23 N grows vertically. 
     Therefore, the side surface of the SAM  23 B (the side surface generated in the film thickness direction) at the boundary between the first region A 1  and the second region A 2  is vertically to the surface of the conductive film  21 . That is, the shape of the SAM  23 B can be controlled such that the boundary adjacent to the second region A 2  on which the target film  14  is formed has an upright shape. 
     Therefore, it is possible to provide a film forming method capable of controlling the shape of the SAM  23 B. 
     In addition, the side surface of the target film  14 , which is formed adjacent to the side surface of the SAM  13 C, at the boundary between the first region A 1  and the second region A 2  is vertical to the surfaces of the conductive film  21  and the insulating film  12 . The fact that the target film  14  has a vertical side surface as described above is very effective in dealing with nanometer-level miniaturization in a semiconductor manufacturing process or the like after removing the CNTs  23 A and the SAM  23 B by etching. 
     Therefore, according to the film forming method according to the present embodiment, it is possible to deal with the nanometer-level miniaturization so that a highly productive semiconductor manufacturing process can be realized. 
     In the foregoing, the mode in which the antirust film  21 A is provided on the surface of the conductive film  21 , and thus the CNTs  23 A are formed after removing the antirust film  21 A has been described. However, when the antirust film  21 A is not provided, the oxide film on the surface of the conductive film  21  may be reduced and removed. The reduction process may be implemented by causing the H 2  gas to flow into the processing container and performing an annealing process at, for example, about 350 degrees C. 
     In addition, when forming the CNTs  23 A on the surface of the conductive film  21  in step S 203 , catalyst metal fine particles may be formed on the surface of the conductive film  21  and then the CNTs  23 A may be formed as in the first embodiment. The catalyst metal fine particles may be made of a metal having a catalytic action in the formation of the CNTs  23 A, and may be made of, for example, Co. 
     &lt;Film Forming System&gt; 
     Next, a system for carrying out the film forming method according to the embodiment of the present disclosure will be described. 
     The film forming method according to an embodiment of the present disclosure may be executed in any of a batch apparatus, a single-wafer apparatus, and a semi-batch apparatus. However, the optimum temperature may differ in each of the above steps, and the execution of each step may be hindered when the surface of a substrate is oxidized and thus a state of the surface is changed. In view of this point, a multi-chamber-type single-wafer film forming system, in which each step can be easily set to an optimum temperature and all steps can be performed in a vacuum, is appropriate. 
     Hereinafter, this multi-chamber-type single-wafer film forming system will be described. 
       FIG.  5    is a schematic view illustrating an example of the film forming system for executing the film forming method according to the embodiment. Here, unless otherwise specified, a case in which a process is performed on the substrate  10  will be described. 
     As illustrated in  FIG.  5   , a film forming system  100  includes a reduction/oxidation processing apparatus  200 , an SAM forming apparatus  300 , a target film forming apparatus  400 , and a processing apparatus  500 . These apparatuses are connected to four walls of a vacuum transfer chamber  101  having a heptagonal shape in a plan view via gate valves G, respectively. The interior of the vacuum transfer chamber  101  is evacuated by a vacuum pump, and is maintained at a predetermined degree of vacuum. That is, the film forming system  100  is a multi-chamber-type vacuum-processing system, and is capable of continuously carrying out the above-described film forming method without breaking a vacuum state. 
     The oxidation/reduction processing apparatus  200  is a processing apparatus used when the reduction process of the substrate  10  (see  FIG.  2 A ) is performed in a processing apparatus different from those for the catalyst metal fine particles  13 A and the CNT  13 B. 
     The SAM forming apparatus  300  is an apparatus that selectively forms an SAM  13 C or  13 B by supplying a thiol-based organic component for forming the SAM  13 C or  23 B in order to form the SAM  13 C on the substrate  10  (see  FIG.  2 D ) or the SAM  23 B on the substrate  20  (see  FIG.  4 D ). 
     The target film forming apparatus  400  is an apparatus that forms a silicon oxide (SiO) film or the like as a target film  14  on the substrate  10  (see  FIG.  2 E ) and the substrate  20  (see  FIG.  4 F ) through CVD or ALD. 
     The processing apparatus  500  is an apparatus that performs a reduction process for the substrate  10  (see  FIG.  2 A ), a process for forming the catalyst fine particles  13 A on the substrate  10  (see  FIGS.  2 B and  2 C ), a process for forming the CNTs  13 B or  23 A (see  FIGS.  2 D and  4 C ), and a process for removing the SAM  13 C or  23 B (see  FIGS.  2 E and  4 D ) by etching. 
     Three load-lock chambers  102  are connected to the other three walls of the vacuum transfer chamber  101  via gate valves G 1 , respectively. An atmospheric transfer chamber  103  is provided on the side opposite to the vacuum transfer chamber  101 , with the load-lock chambers  102  interposed therebetween. The three load-lock chambers  102  are connected to the atmospheric transfer chamber  103  via the gate valves G 2 , respectively. The load-lock chambers  102  perform pressure control between the atmospheric pressure and the vacuum when the substrate  10  is transferred between the atmospheric transfer chamber  103  and the vacuum transfer chamber  101 . 
     The wall of the atmospheric transfer chamber  103  opposite to the wall, on which the load-lock chambers  102  are mounted, includes three carrier mounting ports  105  in each of which a carrier (a FOUP or the like) C for accommodating the substrate  10  is installed. In addition, on a side wall of the atmospheric transfer chamber  103 , an alignment chamber  104  configured to perform alignment of the substrate  10  is provided. The atmospheric transfer chamber  103  is configured to form a down-flow of clean air therein. 
     In the vacuum transfer chamber  101 , a first transfer mechanism  106  is provided. The first transfer mechanism  106  transfers the substrate  10  to the reduction/oxidation processing apparatus  200 , the SAM forming apparatus  300 , the target film forming apparatus  400 , the processing apparatus  500 , and the load-lock chambers  102 . The first transfer mechanism  106  includes two independently-movable transfer arms  107   a  and  107   b.    
     A second transfer mechanism  108  is provided inside the atmospheric transfer chamber  103 . The second transfer mechanism  108  is configured to transfer the substrate  10  to the carriers C, the load-lock chambers  102 , and the alignment chamber  104 . 
     The film forming system  100  includes an overall controller  110 . The overall controller  110  includes a main controller equipped with a CPU (a computer), an input device (a keyboard, a mouse, or the like), an output device (e.g., a printer), a display device (a display or the like), and a storage device (a storage medium). The main controller controls respective components of the oxidation/reduction processing apparatus  200 , the SAM forming apparatus  300 , the target film forming apparatus  400 , the processing apparatus  500 , the vacuum transfer chamber  101 , and the load-lock chambers  102 . The main controller of the overall controller  110  causes the film forming system  100  to execute operations for carrying out the film forming methods of the first and second embodiments based on a processing recipe stored in, for example, a storage medium embedded in the storage device or set in the storage device. Each apparatus may be provided with a lower-level controller, and the overall controller  110  may be configured as an upper-level controller. 
     In the film forming system configured as described above, the second transfer mechanism  108  takes out the substrate  10  from the carrier C connected to the atmospheric transfer chamber  103 , passes through the alignment chamber  104 , and then loads the substrate  10  into one of the load-lock chambers  102 . Then, after the interior of the load-lock chamber  102  is evacuated, the first transfer mechanism  106  transfers the substrate  10  to the reduction/oxidation processing apparatus  200 , the SAM forming apparatus  300 , the target film forming apparatus  400 , and the processing apparatus  500  so as to perform the film forming processes of the first or second embodiment. Then, if necessary, the processing apparatus  500  removes the SAM  13 C by etching. 
     After the above-described processes are completed, the substrate  10  is transferred to one of the load-lock chambers  102  by the first transfer mechanism  106 , and the substrate  10  inside the load-lock chamber  102  is returned to the carrier C by the second transfer mechanism  108 . 
     By performing the above-described processes on the plurality of substrates  10  in a simultaneous and parallel manner, selective film forming processes on a predetermined number of substrates  10  are completed. 
     Since each of these processes is performed by an independent single-wafer apparatus, it is easy to set the optimum temperature for each process, and since a series of processes can be performed without breaking a vacuum state, it is possible to suppress oxidation during the processes. 
     &lt;Examples of Film Forming and SAM Forming Apparatus&gt; 
     Next, examples of the oxidation/reduction processing apparatus  200 , a film forming apparatus such as the target film forming apparatus  400 , and the SAM forming apparatus  300  will be described. 
       FIG.  6    is a cross-sectional view illustrating an example of a processing apparatus that can be used as the film forming apparatus and the SAM forming apparatus. 
     The oxidation/reduction processing apparatus  200 , the film forming apparatus such as the target film forming apparatus  400 , and the SAM forming apparatus  300  may be configured as apparatuses having similar configurations, and may be configured as, for example, a processing apparatus  600  illustrated in  FIG.  6   . 
     The processing apparatus  600  includes a substantially cylindrical processing container (chamber)  601  configured to be hermetically sealed, and a susceptor  602  configured to horizontally support the substrate  10  thereon is disposed inside the processing container  601  to be supported by a cylindrical support member  603  provided in the center of the bottom wall of the processing container  601 . A heater  605  is embedded in the susceptor  602 . The heater  605  heats the substrate  10  to a predetermined temperature by being fed with power from a heater power supply  606 . The susceptor  602  is provided with a plurality of wafer lifting pins (not illustrated) to move upward and downward with respect to the surface of the susceptor  602  so as to support and raise/lower the substrate  10 . 
     A shower head  610  configured to introduce a processing gas for forming a film or an SAM into the processing container  601  in the form of a shower is provided on the ceiling wall of the processing container  601  to face the susceptor  602 . The shower head  610  is provided to eject a gas supplied from a gas supply mechanism  630 , which will be described later, into the processing container  601 . A gas inlet port  611  for gas introduction is formed in the upper portion of the shower head  610 . A gas diffusion space  612  is formed inside the shower head  610 , and a large number of gas ejection holes  613  communicating with the gas diffusion space  612  are formed in the bottom surface of the shower head  610 . 
     The bottom wall of the processing container  601  is provided with an exhaust chamber  621 , which protrudes downwards. An exhaust pipe  622  is connected to the side surface of the exhaust chamber  621 , and an exhaust apparatus  623  including a vacuum pump, a pressure control valve and the like is connected to the exhaust pipe  622 . By operating the exhaust apparatus  623 , the interior of the processing container  601  can be brought into a predetermined depressurized (vacuum) state. 
     A loading/unloading port  627  for loading/unloading the substrate  10  to/from the vacuum transfer chamber  101  is provided in the side wall of the processing container  601 . The loading/unloading port  627  is opened and closed by a gate valve G. 
     The gas supply mechanism  630  includes, for example, sources of gases necessary for forming the target film  14  or the SAM  13 C, individual pipes for supplying gas from respective sources, an opening/closing valve provided in each of the individual pipes, and a flow rate controller such as a mass flow controller that performs flow rate control of a gas, and further includes a gas supply pipe  635  configured to guide a gas from each of the individual pipes through the gas inlet port  611 . 
     When the processing apparatus  600  performs ALD film formation of silicon oxide (SiO) as the target film  14 , the gas supply mechanism  630  supplies a raw material gas of an organic compound and a reaction gas to the shower head  610 . In addition, when the processing apparatus  600  forms an SAM, the gas supply mechanism  630  supplies vapor of a compound for forming the SAM into the processing container  601 . The gas supply mechanism  630  is configured to be able to supply an inert gas such as a N 2  gas or an Ar gas as a purge gas or a heat transfer gas as well. 
     In the processing apparatus  600  configured as described above, the gate valve G is opened, and the substrate  10  is loaded into the processing container  601  through the loading/unloading port  627 , and is placed on the susceptor  602 . Since the susceptor  602  is heated to a predetermined temperature by the heater  605 , the wafer is heated when the inert gas is introduced into the processing container  601 . Then, the interior of the processing container  601  is evacuated by the vacuum pump of the exhaust apparatus  623  such that the internal pressure of the processing container  601  is adjusted to a predetermined pressure. 
     Subsequently, when the processing apparatus  600  performs ALD film formation of silicon oxide (SiO) as the target film  14 , supply of the raw material gas of the organic compound and supply of the reaction gas from the gas supply mechanism  630  are alternately performed, with purging of the interior of the processing container  601  interposed between the supply of the raw material gas and the supply of the reaction gas. When the processing apparatus  600  forms an SAM, the gas supply mechanism  630  supplies the vapor of the organic compound for forming the SAM into the processing container  601 . 
     Although embodiments of the substrate processing method according to the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations can be made within the scope of the claims. Of course, these also fall within the technical scope of the present disclosure. 
     The present international application claims priority based on Japanese Patent Application No. 2019-173471 filed on Sep. 24, 2019, the disclosure of which is incorporated herein in its entirety by reference. 
     EXPLANATION OF REFERENCE NUMERALS 
       10 ,  20 : substrate,  11 ,  21 : conductive film,  11 A: natural oxide film,  12 : insulating film,  13 A: catalyst metal fine particles,  13 B,  23 A: CNT,  13 C,  23 B: SAM,  14 : target film,  15 : base substrate,  21 A: antirust film