Patent Publication Number: US-2023135342-A1

Title: Film forming method and film forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-179687, filed on Nov. 2, 2021, and Japanese Patent Application No. 2022-147033, filed on Sep. 15, 2022, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a film forming method and a film forming apparatus. 
     BACKGROUND 
     A method of forming a nitride film, which is described in Patent Document 1, includes a process of adsorbing a chlorine gas on surfaces of a first base film and a second base film, and a process of selectively forming a nitride film on one of the first base film and the second base film on which the chlorine gas is adsorbed. 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     
         
         Patent Document 1: Japanese Patent Laid-Open Publication No. 2017-174919 
       
    
     SUMMARY 
     According to one embodiment of the present disclosure, there is provided a film forming method including: preparing a substrate having a surface on which a first film containing boron and a second film made of a material different from that of the first film are formed; supplying a raw material gas, which contains halogen and an element X other than halogen, to the surface of the substrate; and supplying a plasmarized reaction gas, which contains oxygen, to the surface of the substrate, wherein a third film as an oxide film of the element X is selectively formed on the second film with respect to the first film by alternately supplying the raw material gas and the plasmarized reaction gas. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure. 
         FIG.  1    is a flowchart showing a film forming method according to one embodiment. 
         FIG.  2    is a view showing a first example of a substrate prepared in step S 101 . 
         FIG.  3    is a view showing a second example of the substrate prepared in step S 101 . 
         FIG.  4    is a view showing a third example of the substrate prepared in step S 101 . 
         FIG.  5    is a view showing a fourth example of the substrate prepared in step S 101 . 
         FIG.  6    is a view showing a fifth example of the substrate prepared in step S 101 . 
         FIG.  7    is a view showing a sixth example of the substrate prepared in step S 101 . 
         FIG.  8    is a view showing a seventh example of the substrate prepared in step S 101 . 
         FIG.  9    is a flowchart showing an example of steps S 201  to S 205  performed in step S 101 . 
         FIG.  10    is a view showing an eighth example of the substrate prepared in step S 101 . 
         FIG.  11    is a cross-sectional view showing a film forming apparatus according to one embodiment. 
         FIG.  12    is an SEM photograph showing a substrate before being subjected to a process of Case 1. 
         FIG.  13    is an SEM photograph showing a substrate after being subjected to the process of Case 1. 
         FIG.  14    is an SEM photograph showing a substrate before being subjected to a process of Case 9. 
         FIG.  15    is an SEM photograph showing a substrate after being subjected to the process of Case 9. 
         FIG.  16    is an SEM photograph showing a substrate before being subjected to a process of Case 13. 
         FIG.  17    is an SEM photograph showing a substrate after being subjected to the process of Case 13. 
         FIG.  18    is an SEM photograph showing a substrate before being subjected to a process of Case 14. 
         FIG.  19    is an SEM photograph showing a substrate after being subjected to the process of Case 14. 
         FIG.  20    is a flowchart showing a film forming method according to a modification. 
         FIG.  21    is a flowchart showing a procedure when K in  FIG.  20    is an integer of two or more. 
         FIG.  22    is a view showing an example of a process of  FIG.  21   . 
         FIG.  23    is a view showing another example of the process of  FIG.  21   . 
         FIG.  24    is a view showing a ninth example of the substrate prepared in step S 101 . 
         FIG.  25    is a view showing a tenth example of the substrate prepared in step S 101 . 
         FIG.  26    is an SEM photograph showing a substrate before being subjected to a process of Case 15. 
         FIG.  27    is an SEM photograph showing a substrate after being subjected to the process of Case 15. 
         FIG.  28    is an SEM photograph showing a substrate before being subjected to a process of Case 16. 
         FIG.  29    is an SEM photograph showing a substrate after being subjected to the process of Case 16. 
         FIG.  30    is an SEM photograph showing a substrate before being subjected to a process of Case 17. 
         FIG.  31    is an SEM photograph showing a substrate after being subjected to the process of Case 17. 
         FIG.  32    is a flowchart showing a film forming method according to a second modification. 
         FIG.  33    is an SEM photograph showing a substrate before being subjected to a process of Case 5. 
         FIG.  34    is an SEM photograph showing a substrate after being subjected to the process of Case 5. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, systems, and components have not been described in detail so as not to unnecessarily obscure aspects of the various embodiments. 
     Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Throughout the drawings, the same or corresponding constituent elements are denoted by the same reference numerals, and explanations thereof may be omitted. 
     First, a film forming method according to one embodiment will be described with reference to  FIG.  1   . The film forming method includes, for example, steps S 101  to S 106  shown in  FIG.  1   . Note that the film forming method may include at least steps S 101 , S 102 , and S 104 . The order of steps S 102  and S 104  may be reversed, and step S 104  may be performed before step S 102 . The film forming method may include steps other than steps S 101  to S 106  shown in  FIG.  1   . 
     Step S 101  of  FIG.  1    includes preparing a substrate W (see  FIG.  2   ). The substrate W has a first film W 1  and a second film W 2  on a surface Wa of the substrate W. The first film W 1  and the second film W 2  are formed, for example, on a base substrate (not shown). The base substrate is a silicon wafer or a compound semiconductor wafer. The compound semiconductor wafers are, for example, a GaAs wafer, a SiC wafer, a GaN wafer, or an InP wafer. 
     The first film W 1  contains boron (B). A boron (B) content in the first film W 1  is, for example, 20 atom % to 100 atom %, specifically 40 atom % to 100 atom %. The first film W 1  is, for example, a B film, a BN film, a BNC film, a BO film, a BNOC film, a SiBN film, a SiBCN film, or a SiOBN film. Here, the BN film means a film containing boron (B) and nitrogen (N). An atomic ratio of B and N in the BN film is not limited to 1:1. The BNC film and the like other than the BN film also mean including individual elements in the same manner, and are not limited to the stoichiometric ratio. 
     The second film W 2  is made of a material different from that of the first film W 1 . The second film W 2  contains substantially no B. “Containing substantially no B” means that a boron (B) content is 0 atom % to 5 atom %. It is more desirable as the boron (B) content in the second film W 2  decreases. The second film W 2  may be any one of an insulating film, a conductive film, and a semiconductor film. 
     The insulating film is not particularly limited, but is, for example, a SiO film, a SiN film, a SiOC film, a SiON film, a SiOCN film, an AlO film, a ZrO film, a HfO film, or a TiO film. Here, the SiO film means a film containing silicon (Si) and oxygen (O). An atomic ratio of Si and O in the SiO film is usually 1:2, but is not limited to 1:2. The SiN film, the SiOC film, the SiON film, the SiOCN film, the AlO film, the ZrO film, the HfO film, and the TiO film also mean containing individual elements, and are not limited to the stoichiometric ratio. The insulating film is, for example, an interlayer insulating film. The interlayer insulating film is desirably a low dielectric constant (low-k) film. 
     The semiconductor film is not particularly limited, but is, for example, a Si film, a SiGe film, or a GaN film. The semiconductor film may be any one of a monocrystalline film, a polycrystalline film, or an amorphous film. 
     The conductive film is, for example, a metal film. The metal film is not particularly limited, but is, for example, a Cu film, a Co film, a Ru film, a Mo film, a W film, or a Ti film. The conductive film may be a metal nitride film. The metal nitride film is not particularly limited, but it may be, for example, a TiN film or a TaN film. Here, the TiN film means a film containing titanium (Ti) and nitrogen (N). An atomic ratio of Ti and N in the TiN film is usually 1:1, but is not limited to 1:1. The TaN film also means containing individual elements, and is not limited to the stoichiometric ratio. 
     Step S 102  of  FIG.  1    includes supplying a raw material gas to the surface Wa of the substrate W. The raw material gas contains a halogen element and an element X other than the halogen element. The halogen element is fluorine, chlorine, bromine, or iodine. The element X is not particularly limited as long as it is oxidized in step S 104 , but is desirably a metal element, more specifically a transition metal element. The transition metal element is, for example, Ti, W, V, Al, Mo, Sn, or Hf Specific examples of the raw material gas may include TiCl 4  gas, WCl 6  gas, VCl 4  gas, AlCl 3  gas, MoCl 5  gas, SnCl 4  gas, and HfCl 4  gas. The element X may be a semiconductor element, in particular Si or Ge. The raw material gas is a silicon halide gas or a germanium halide gas. Specific examples of the silicon halide gas may include SiCl 4  gas, SiHCl 3  gas, SiH 2 Cl 2  gas, SiH 3 Cl gas, Si 2 Cl 6  gas, Si 2 HCl 5  gas, SiH 2 I 2  gas, SiCl 3 CH 3  gas, and the like. Specific examples of the germanium halide gas may include GeCl 4  gas and the like. The raw material gas may be supplied together with a dilution gas. The dilution gas is, for example, Ar gas or N 2  gas. 
     Step S 103  of  FIG.  1    includes supplying a purge gas to the surface Wa of the substrate W. The purge gas purges the excessive raw material gas that has not been adsorbed to the surface Wa of the substrate W in step S 102 . As the purge gas, for example, a rare gas such as Ar gas or N 2  gas is used. 
     Step S 104  of  FIG.  1    includes supplying a reaction gas to the surface Wa of the substrate W. Step S 104  includes plasmarizing the reaction gas and supplying the plasmarized reaction gas to the surface Wa of the substrate W. The reaction gas contains oxygen and oxidizes the element X contained in the adsorbed raw material gas to form a third film W 3  as an oxide film of the element X (see  FIG.  2   ). The reaction gas is, for example, O 2  gas, O 3  gas), CO 2  gas, N 2 O gas, NO gas, or H 2 O gas. The reaction gas may be supplied together with a dilution gas. The dilution gas is, for example, Ar gas or N 2  gas. 
     Note that the reaction gas may be supplied not only in step S 104  but also in all of steps S 102  to S 105 . However, plasmarizing the reaction gas is performed in step S 104  only. The reason is because, by being plasmarized, the reaction gas becomes more likely to react with the raw material gas adsorbed on the surface Wa of the substrate W. 
     Step S 105  of  FIG.  1    includes supplying a purge gas to the surface Wa of the substrate W. The purge gas purges the excessive reaction gas that has not reacted with the surface Wa of the substrate W in step S 104 . As the purge gas, for example, a rare gas such as Ar gas or N 2  gas is used. 
     In step S 106  in  FIG.  1   , it is determined whether or not steps S 102  to S 105  have been performed N times (N is an integer of one or more). N may be an integer of two or more, and steps S 102  to S 105  may be repeatedly performed. A film thickness of the third film W 3  may be increased. 
     When an execution number of steps S 102  to S 105  is less than N times (“NO” in step S 106 ), the film thickness of the third film W 3  is less than a target value. Thus, steps S 102  to S 105  are performed again. N is desirably 200 or more, more specifically 300 or more. N is desirably 1,000 or less. 
     On the other hand, when the execution number of steps S 102  to S 105  reaches N times (“YES” in step S 106 ), the film thickness of the third film W 3  has reached the target value. Thus, the current process ends. 
     According to the present embodiment, the third film W 3  is selectively formed on the second film W 2  with respect to the first film W 1  by a plasma atomic layer deposition (ALD) method. In order to selectively form the third film W 3 , it is important to desorb the raw material gas, which is weakly adsorbed on the first film W 1 , without advancing a film forming reaction (formation of the third film W 3 ) by collision or reaction with the plasmarized reaction gas. 
     Easiness of desorbing the raw material gas adsorbed on the first film W 1  varies according to a strength of adsorption of the raw material gas on the first film W 1 , and thus varies according to a material of the first film W 1 . The easiness of desorbing the raw material gas adsorbed on the first film W 1  varies according to whether or not the raw material gas is dissociated by reaction with atoms on the surface of the first film W 1  and becomes molecules that are easily oxidized in subsequent reactions. It is considered that on the first film W 1  containing boron, compared to the second film W 2  containing substantially no boron, adsorption of the halide, which is the raw material gas, is weak or does not occur, or dissociation of the halide is difficult to occur. 
     Oxygen ions or oxygen radicals are generated by plasmarizing the reaction gas containing oxygen. The oxygen ions are accelerated by a potential of the plasma and collide with the substrate W. It is considered that collision of the accelerated oxygen ions or oxygen radicals causes sputtering that physically knocks off a substance on the surface Wa. Alternatively, it is considered that the oxygen ions or oxygen radicals chemically react with the substance on the surface Wa to form a film. 
     The halide adsorbed on the second film W 2  containing substantially no boron is either strongly adsorbed or dissociated into easily oxidizable molecules, and thus, is easily oxidized by collision with the oxygen ions or oxygen radicals. Therefore, it is considered that formation of an oxide film proceeds on the second film W 2 . On the other hand, the halide adsorbed on the first film W 1  containing boron is either weakly adsorbed or not dissociated into easily oxidizable molecules, and thus, is knocked off by the collision of the oxygen ions or oxygen radicals. Therefore, it is considered that the formation of the oxide film does not proceed on the first film W 1 . 
     It is also considered that the reason why the formation of the oxide film does not proceed on the first film W 1  is because the halide is desorbed by sputtering or chemical reaction, or the first film W 1  is etched by the collision of the oxygen ions or oxygen radicals to cause the halide to lift off. 
     Further, as shown in  FIG.  32   , step S 109  may be performed instead of step S 104 . Step S 109  includes supplying O 3  gas) to the surface Wa of the substrate W without plasmarizing the O 3  gas). Since the O 3  gas) is supplied without being plasmarized, it does not initially contain oxygen ions and oxygen radicals. The O 3  gas) collides with the surface Wa of the heated substrate W to generate oxygen radicals. The oxygen radicals oxidize the halide adsorbed on the second film W 2  containing substantially no boron, and formation of an oxide film proceeds. On the other hand, the halide adsorbed on the first film W 1  containing boron is knocked off, and the formation of the oxide film does not proceed. 
     Further, even when a reaction gas containing no oxygen, such as H 2  gas or NH 3  gas, is plasmarized, active species such as ions or radicals are also generated, but these active species facilitate the film forming reaction. Therefore, it is considered that when the reaction gas containing no oxygen is used, the film forming reaction is likely to proceed not only on the second film W 2  but also on the first film W 1 , resulting in loss of selectivity. Therefore, a gas containing oxygen is appropriate as a gas to be plasmarized. 
     Further, the halide adsorbed on the first film W 1  is less likely to be decomposed by the collision with the oxygen ions or oxygen radicals. For example, the halide such as TiCl 4  are less likely to be decomposed by the collision with the oxygen ions or oxygen radicals than an organometallic complex such as Ti[N(CH 3 ) 2 ] 4 . In order to desorb the halide adsorbed on the first film W 1  from the first film W 1 , it is important that the halide is difficult to be decomposed by the collision with the oxygen ions or oxygen radicals and by heat from the substrate. Therefore, a gas containing halogen is appropriate as the raw material gas. 
     Further, in a plasma chemical vapor deposition (CVD) method in which both halide and oxygen are plasmarized, active species such as ions or radicals generated by dissociation of the halide are generated in addition to oxygen ions or oxygen radicals. It is considered that since the active species generated from the halide has high reactivity, the film forming reaction is likely to proceed not only on the second film W 2  but also on the first film W 1 , resulting loss of selectivity. It is important to use a plasma ALD method in order to produce the selectivity. 
     In steps S 102  to S 105 , a temperature of the substrate W may be controlled to 100 degrees C. or higher in order to promote desorption of the raw material gas from the first film W 1 . When the temperature of the substrate W is less than 100 degrees C., the raw material gas is physically adsorbed on the first film W 1  without being sufficiently desorbed from the first film W 1 , so that the third film W 3  is formed on the entire surface Wa of the substrate W. The temperature of the substrate W is desirably 300 degrees C. or higher. The temperature of the substrate W is desirably 800 degrees C. or lower. 
     Next, a case where the substrate W prepared in step S 101  has recesses Wa 1  on the surface Wa of the substrate W and the second film W 2  is exposed only inside the recesses Wa 1  will be described with reference to  FIGS.  3  to  5   . As shown in  FIGS.  3  to  5   , the second film W 2  is exposed at least at bottom surfaces of the recesses Wa 1 . In this case, by performing steps S 102  to S 106 , interiors of the recesses Wa 1  can be filled with the third film W 3 . Although the third film W 3  partially fills the recesses Wa 1  in  FIGS.  3  to  5   , the third film W 3  may fill the entire recesses Wa 1 . In the latter case, in  FIG.  5   , the first film W 1  may be left only on top surface of a protrusions of the second film W 2  by etching. 
     In step S 101  of  FIG.  3   , first, the first film W 1  is formed on the entire surface of the second film W 2 , and then portions of a surface of the first film W 1  are etched. As a result, the recesses Wa 1  are formed through the portions of the first film W 1 , and the second film W 2  is exposed only at the bottom surfaces of the recesses Wa 1 . Thereafter, by performing steps S 102  to S 106 , the third film W 3  grows only on the bottom surfaces of the recesses Wa 1 . 
     In step S 101  of  FIG.  4   , first, portions of the surface of the second film W 2  are etched to form recesses on the surface of the second film W 2 . Next, the first film W 1  is formed to fill the recesses. Next, the first film W 1  is processed by chemical mechanical polishing (CMP) or etching until the second film W 2  is exposed. Finally, the second film W 2  is selectively etched with respect to the first film W 1 . As a result, the recesses Wa 1  are formed through portions of the first film W 1 , and the second film W 2  is exposed only at the bottom surfaces of the recesses Wa 1 . Thereafter, by performing steps S 102  to S 106 , the third film W 3  grows only on the bottom surfaces of the recesses Wa 1 . 
     In step S 101  of  FIG.  5   , first, portions of the surface of the second film W 2  are etched to form recesses on the surface of the second film W 2 . Next, the first film W 1  is selectively formed on the outside of the recesses (that is, on the top surfaces of the protrusions) with respect to the inside of the recess. As a result, the second film W 2  is exposed at the bottom and lower side surfaces of the recesses Wa 1 . Further, when the first film W 1  is also deposited on the bottom surfaces of the recesses Wa 1  during step S 101 , the first film W 1  deposited on the bottom surfaces is removed by etching or the like. Thereafter, by performing steps S 102  to S 106 , the third film W 3  grows on the bottom and lower side surfaces of the recesses Wa 1 . 
     Next, a case where the substrate W prepared in step S 101  has the recesses Wa 1  on the surface Wa of the substrate W and the first film W 1  is exposed only inside the recesses Wa 1  will be described with reference to  FIGS.  6  to  8   . As shown in  FIGS.  6  to  8   , the first film W 1  is exposed at least at the bottom surfaces of the recesses Wa 1 . In this case, by performing steps S 102  to S 106 , the third film W 3  can be formed on regions other than the bottom surfaces of the recesses Wa 1 . 
     In step S 101  of  FIG.  6   , first, the second film W 2  is formed on the entire surface of the first film W 1 , and then portions of the surface of the second film W 2  are etched. As a result, the recesses Wa 1  are formed through the portions of the second film W 2 , and the first film W 1  is exposed only at the bottom surfaces of the recesses Wa 1 . Thereafter, by performing steps S 102  to S 106 , the third film W 3  grows on the side surfaces of the recesses Wa 1  and the outside of the recesses Wa 1  (the top surfaces of the protrusions). 
     In step S 101  of  FIG.  7   , first, portions of the surface of the first film W 1  are etched to form recesses on the surface of the first film W 1 . Next, the second film W 2  is formed to fill the recesses. Next, the second film W 2  is processed by chemical mechanical polishing (CMP) or etching until the first film W 1  is exposed. Finally, the first film W 1  is selectively etched with respect to the second film W 2 . As a result, the recesses Wa 1  are formed through portions of the second film W 2 , and the first film W 1  is exposed only at the bottom surfaces of the recesses Wa 1 . Thereafter, by performing steps S 102  to S 106 , the third film W 3  grows on the side surfaces of the recesses Wa 1  and the outside of the recesses Wa 1  (the top surfaces of the protrusions). 
     In step S 101  of  FIG.  8   , first, portions of the surface of the first film W 1  are etched to form recesses on the surface of the first film W 1 . Next, the second film W 2  is selectively formed on the outside of the recesses (that is, on the top surfaces of the protrusions) with respect to the inside of the recesses. As a result, the first film W 1  is exposed at the bottom and lower side surfaces of the recesses Wa 1 . Further, when the second film W 2  is also deposited on the bottom surfaces of the recesses Wa 1  during step S 101 , the second film W 2  deposited on the bottom surfaces is removed by etching or the like. Thereafter, by performing steps S 102  to S 106 , the third film W 3  grows on the outside of the recesses Wa 1  (that is, on the top surfaces of the protrusions) and on the upper side surfaces of the recesses Wa 1 . As shown in  FIG.  8   , the third film W 3  may confine voids (air gaps) inside the recesses Wa 1 . 
     Next, a modification of step S 101  will be described with reference to  FIGS.  9  and  10   . As shown in  FIG.  10   , step S 101  may include selectively forming the first film W 1  on a fourth film W 4 , which is formed of a material different from that of the second film W 2 , with respect to the second film W 2 . The first film W 1  contains boron as described above. 
     The fourth film W 4  may be any one of an insulating film, a conductive film, and a semiconductor film as long as the first film W 1  can be selectively formed on the fourth film W 4  with respect to the second film W 2 . For example, an incubation time of the first film W 1  with respect to the second film W 2  may be longer than an incubation time of the first film W 1  with respect to the fourth film W 4 . The first film W 1  can be selectively formed using the difference in incubation time. 
     The incubation time is a time difference from a start of a film forming process (for example, a start of supplying the raw material gas or the reaction gas) to an actual start of film formation. 
     Step S 101  includes steps S 201  to S 205  shown in  FIG.  9   , for example. Note that step S 101  may include at least steps S 201  and S 203 . The order of steps S 201  and S 203  may be reversed, and step S 203  may be performed before step S 201 . Steps S 201  and S 203  may be performed simultaneously, and a CVD method may be used. 
     Step S 201  of  FIG.  9    includes supplying a second raw material gas to the surface of the substrate W. The second raw material gas contains boron. The second raw material gas contains, for example, trisdimethylaminoborane (TDMAB: C 6 H 18 BN 3 ). The second raw material gas may be supplied together with a dilution gas. The dilution gas is, for example, Ar gas or N 2  gas. 
     The second raw material gas is not limited to a gas containing TDMAB, and may be a gas containing boron. For example, the second raw material gas may include diborane (B 2 H 6 ), boron trichloride (BCl 3 ), boron trifluoride (BF 3 ), tri sethylmethylaminoborane (C 9 H 24 BN 3 ), trimethylborane (C 3 H 9 B), triethylborane (C 6 H 15 B), cyclotriborazane (B 3 N 3 H 6 ), or the like. 
     Step S 202  of  FIG.  9    includes supplying a purge gas to the surface of the substrate W. The purge gas purges the excessive second raw material gas that has not been adsorbed to the surface Wa of the substrate W in step S 201 . As the purge gas, for example, a rare gas such as Ar gas or N 2  gas is used. 
     Step S 203  of  FIG.  9    includes supplying a second reaction gas to the surface of the substrate W. The second reaction gas contains, for example, nitrogen and forms the first film W 1  (for example, a BN film) by nitriding the adsorbed second raw material gas. The second reaction gas includes, for example, a mixture of N 2  gas and H 2  gas, or NH 3  gas. The second reaction gas may be supplied together with a dilution gas. The dilution gas is, for example, Ar gas or N 2  gas. 
     In addition, the second reaction gas may contain at least one of a nitrogen-containing gas, an oxygen-containing gas, and a reducing gas. The nitrogen-containing gas forms a boron nitride film by nitriding the second raw material gas. The nitrogen-containing gas includes, for example, NH 3 , N 2 , N 2 H 4 , or N 2 H 2 . The oxygen-containing gas forms a boron oxide film by oxidizing the second raw material gas. The oxygen-containing gas includes, for example, O 2 , O 3 , H 2 O, NO, or N 2 O. The reducing gas forms a boron film by reducing the second raw material gas. The reducing gas includes, for example, H 2  or SiH 4 . 
     Step S 203  may include plasmarizing the second reaction gas, and may include supplying the plasmarized second reaction gas to the surface Wa of the substrate W. The formation of the first film W 1  can be promoted by plasmarizing the second reaction gas. 
     In addition, the second reaction gas may be supplied not only in step S 203  but also in all of steps S 201  to S 204 . However, the second reaction gas is plasmarized in step S 203  only. The reason is because a reaction of the second reaction gas with the second raw material gas adsorbed on the surface of the substrate W is promoted by being plasmarized. 
     Step S 204  of  FIG.  9    includes supplying a purge gas to the substrate W surface. The purge gas purges the excessive second reaction gas that has not reacted with the surface Wa of the substrate W in step S 203 . As the purge gas, for example, a rare gas such as Ar gas or N 2  gas is used. 
     In step S 205  of  FIG.  9   , it is determined whether or not steps S 201  to S 204  have been performed M times (M is an integer of one or more). M may be an integer of two or more, and steps S 201  to S 204  may be repeatedly performed. A film thickness of the first film W 1  may be increased. 
     When an execution number of steps S 201  to S 204  is less than M times (“NO” in step S 205 ), the film thickness of the first film W 1  is less than a target value, and thus steps S 201  to S 204  are performed again. The target value of the film thickness of the first film W 1  is desirably 300 angstroms or less, specifically 100 angstroms or less, and more specifically 50 angstroms or less. The film thickness of the first film W 1  may be about 5 angstroms. 
     On the other hand, when the execution number of steps S 201  to S 204  reaches M times (“YES” in step S 205 ), the film thickness of the first film W 1  has reached the target value. Thus, the current process ends. 
     The method of forming the first film W 1  shown in  FIG.  9    is an ALD method, but may be a CVD method. In the ALD method, the supply of the second raw material gas and the supply of the second reaction gas are alternately performed. On the other hand, in the CVD method, the supply of the second raw material gas and the supply of the second reaction gas are performed simultaneously. 
     The first film W 1  may be a molecular film in which molecules are chemically adsorbed, such as a self-assembled monolayer (SAM). The molecules are supplied to a substrate surface in a gaseous or liquid form. The molecules have a first functional group that is selectively chemisorbed to a desired region of the substrate surface. The first functional group is not particularly limited, but is, for example, a thiol group (SH group), a carboxy group (COOH group), or a hydroxyl group (OH group). The molecules have a second functional group containing B in addition to the first functional group. The second functional group is a functional group such as BH 3  or B(CH 3 ) 3  in which at least some of carbon atoms in a hydrocarbon group are substituted with boron (B). The first film W 1  may be a thermally decomposed molecular film. 
     Next, a film forming method according to a modification will be described with reference to  FIG.  20   . As shown in  FIG.  20   , the film forming method of this modification includes step  301 , steps S 201  to S 205 , steps S 102  to S 106 , and step S 302 . 
     Steps S 201  to S 205  in  FIG.  20    are the same as steps S 201  to S 205  in  FIG.  9   , and thus explanation thereof will be omitted. Note that the film forming method does not have to include all of steps S 201  to S 205 . It suffices when the first film W 1  can be selectively formed in a desired region. 
     Further, steps S 102  to S 106  in  FIG.  20    are the same as steps S 102  to S 106  in  FIG.  1   , and thus explanation thereof will be omitted. Note that the film forming method does not have to include all of steps S 102  to S 106 . It suffices when the third film W 3  can be selectively formed in a desired region. 
     Step S 301  includes preparing the substrate W having a surface Wa on which the second film W 2  and the fourth film W 4  are formed (see  FIG.  22   ). Thereafter, in steps S 201  to S 205 , the first film W 1  is selectively formed on the fourth film W 4  with respect to the second film W 2 . Thereafter, in steps S 102  to S 106 , the third film W 3  is selectively formed on the second film W 2  with respect to the first film W 1 . 
     Step S 302  includes determining whether or not a series of processes has been performed K times (K is an integer of one or more). The series of processes includes performing steps S 201  to S 204  M times (M is an integer of one or more) and performing steps S 102  to S 105  N times (N is an integer of one or more). 
     When an execution number of the series of processes is less than K times (“NO” in step S 302 ), a film thickness of the third film W 3  is insufficient, and thus a controller  100  performs the series of processes again. On the other hand, when the execution number of the series of processes reaches K times (“YES” in step S 302 ), the controller  100  ends the current process. K is desirably an integer of two or more. When K is an integer of two or more, the film thickness of the third film W 3  can be increased while replenishing the first film W 1 . 
     Next, a film forming method when K is an integer of two or more will be described with reference to  FIGS.  21  to  23   . As shown in  FIG.  21   , the film forming method may include steps S 401  to S 405 . In  FIG.  21   , L is equal to (K−1). 
     Similar to step S 301 , step S 401  includes preparing the substrate W having a surface Wa on which the second film W 2  and the fourth film W 4  are formed (see  FIG.  22   ). The fourth film W 4  may be any one as long as the first film W 1  can be selectively formed on the fourth film W 4  with respect to the second film W 2 . For example, the incubation time of the first film W 1  with respect to the second film W 2  may be longer than the incubation time of the first film W 1  with respect to the fourth film W 4 . 
     Step S 402  includes selectively forming the first film W 1  on the fourth film W 4  with respect to the second film W 2  (see  FIG.  22   ). Step S 402  includes performing steps S 201  to S 204  M times. M is an integer of one or more. M may be an integer of two or more. 
     Step S 403  includes selectively forming the third film W 3  on the second film W 2  with respect to the first film W 1  (see  FIG.  22   ). Step S 403  includes performing steps S 102  to S 105  N times. N is an integer of one or more. N may be an integer of two or more. 
     Step S 404  includes selectively forming the first film W 1  again on the first film W 1  with respect to the third film W 3  (see  FIG.  22   ). Similar to step S 402 , step S 404  includes performing steps S 201  to S 204  M times. 
     In the process of forming the third film W 3  in step S 403 , the first film W 1  may become thin, or the first film W 1  may disappear (see  FIG.  23   ). When the first film W 1  disappears, step S 404  includes selectively forming the first film W 1  again on the fourth film W 4  instead of the first film W 1  (see  FIG.  23   ). 
     Step S 405  includes selectively forming the third film W 3  again on the third film W 3  with respect to the first film W 1 . Similar to step S 403 , step S 405  includes performing steps S 102  to S 105  N times. 
     Step S 406  includes determining whether or not steps S 404  and S 405  have been performed L (L=(K−1)) times. When an execution number of steps S 404  and S 405  is less than L times (“NO” in step S 406 ), the controller  100  performs steps S 404  and S 405  again. On the other hand, when the execution number of steps S 404  and S 405  reaches L times (“YES” in step S 406 ), the controller  100  ends the current process. 
     Next, another modification of step S 101  will be described with reference to  FIG.  24   . In step S 101  of  FIG.  24   , first, the second film W 2  having an uneven pattern is prepared. Subsequently, the first film W 1  is formed along the uneven pattern of the second film W 2  over the entire second film W 2  by an ALD method or a CVD method. Subsequently, top surfaces of protrusions of the second film W 2  are exposed by CMP or etching. At this time, the first film W 1  is left on the side and bottom surfaces of recesses of the second film W 2 . Thereafter, by performing steps S 102  to S 106 , the third film W 3  may be formed on the top surfaces of the protrusions. 
     Next, still another modification of step S 101  will be described with reference to  FIG.  25   . In step S 101  of  FIG.  25   , first, the second film W 2  having an uneven pattern is prepared. Subsequently, the first film W 1  is formed to fill recesses of the second film W 2 . The first film W 1  is a liquid. The liquid is obtained by, for example, polymerizing B-containing molecules having organic ligands such as TDMAB with N 2  plasma or the like. Subsequently, the liquid buried in the recesses of the second film W 2  is decomposed by O 2  plasma or the like, leaving the first film W 1  on the side and bottom surfaces of the recesses of the second film W 2 . Top surfaces of protrusions of the second film W 2  remain exposed. Although not shown, the liquid buried in the recesses of the second film W 2  may be modified with H 2  plasma or the like to form the first film W 1  buried in the recesses of the second film W 2 . Thereafter, by performing steps S 102  to S 106 , the third film W 3  may be formed on the top surfaces of the protrusions. 
     Next, a film forming apparatus  1  will be described with reference to  FIG.  11   . The film forming apparatus  1  includes a substantially cylindrical airtight process container  2 . An exhaust chamber  21  is provided in a central portion of a bottom wall of the process container  2 . The exhaust chamber  21  has, for example, a substantially cylindrical shape protruding downward. An exhaust pipe  22  is connected to the exhaust chamber  21 , for example, on a side surface of the exhaust chamber  21 . 
     An exhauster  24  is connected to the exhaust pipe  22  via a pressure regulator  23 . The pressure regulator  23  includes, for example, a pressure regulating valve such as a butterfly valve. The exhaust pipe  22  is configured so as to depressurize an interior of the process container  2  by the exhauster  24 . A transfer opening  25  is provided on the side surface of the process container  2 . The transfer opening  25  is opened and closed by a gate valve  26 . The substrate W is loaded and unloaded between the process container  2  and a transfer chamber (not shown) via the transfer opening  25 . 
     A stage  3  is provided inside the process container  2 . The stage  3  is a holder that horizontally holds the substrate W with the surface Wa of the substrate W facing upward. The stage  3  has a substantially circular shape in a plan view and is supported by a support  31 . A surface of the stage  3  is formed with a substantially circular recess  32  for placing the substrate W having a diameter of 300 mm, for example. The recess  32  has an inner diameter slightly larger than the diameter of the substrate W. A depth of the recess  32  is substantially the same as the thickness of the substrate W, for example. The stage  3  is made of a ceramic material such as aluminum nitride (AlN). The stage  3  may also be made of a metallic material such as nickel (Ni). Instead of the recess  32 , a guide ring for guiding the substrate W may also be provided on a periphery of the surface of the stage  3 . 
     For example, a grounded lower electrode  33  is buried in the stage  3 . A heating mechanism  34  is buried below the lower electrode  33 . The heating mechanism  34  heats the substrate W placed on the stage  3  to a set temperature by receiving power from a power supply (not shown) based on a control signal from the controller  100 . When the entirety of the stage  3  is made of metal, the entire stage  3  functions as a lower electrode, and thus the lower electrode  33  does not have to be buried in the stage  3 . The stage  3  is provided with a plurality of lift pins  41  (for example, three lift pins  41 ) for holding and lifting the substrate W placed on the stage  3 . A material of the lift pins  41  may be, for example, ceramics such as alumina (Al 2 O 3 ), quartz, or the like. A lower end of each lift pin  41  is attached to a support plate  42 . The support plate  42  is connected to an elevating mechanism  44  provided outside the process container  2  via an elevating shaft  43 . 
     The elevating mechanism  44  is installed, for example, below the exhaust chamber  21 . A bellows  45  is provided between the elevating mechanism  44  and an opening  211  for the elevating shaft  43  formed on a lower surface of the exhaust chamber  21 . A shape of the support plate  42  may be a shape that allows it to move up and down without interfering with the support  31  of the stage  3 . The lifts pins  41  are configured to be vertically movable between a location above the surface of the stage  3  and a location below the surface of the stage  3  by means of the elevating mechanism  44 . 
     A gas supply  5  is provided on a ceiling wall  27  of the process container  2  via an insulator  28 . The gas supply  5  forms an upper electrode and faces the lower electrode  33 . A radio frequency power supply  512  is connected to the gas supply  5  via a matching device  511 . By supplying radio frequency power of 100 kHz to 2.45 GHz, desirably 450 kHz to 100 MHz, from the radio frequency power supply  512  to the upper electrode (the gas supply  5 ), a radio frequency electric field is generated between the upper electrode (the gas supply  5 ) and the lower electrode  33  to generate capacitively-coupled plasma. A plasma generator  51  includes the matching device  511  and the radio frequency power supply  512 . The plasma generator  51  is not limited to generate the capacitively-coupled plasma, and may generate other plasma such as inductively-coupled plasma. In addition, a plasmarized gas may be supplied from a remote plasma source. 
     The gas supply  5  has a hollow gas supply chamber  52 . A plurality of holes  53  for distributing and supplying a process gas into the process container  2  is disposed, for example, evenly on a lower surface of the gas supply chamber  52 . A heating mechanism  54  is buried above, for example, the gas supply chamber  52  in the gas supply  5 . The heating mechanism  54  is heated to a set temperature by receiving power from a power supply (not shown) based on a control signal from the controller  100 . 
     A gas supply path  6  is provided in the gas supply chamber  52 . The gas supply path  6  is in communication with the gas supply chamber  52 . Gas sources G 61 , G 62 , and G 63  are connected to an upstream of the gas supply path  6  via gas lines L 61 , L 62 , and L 63 , respectively. Note that the number of gas sources and the types of gases are not limited to those shown in  FIG.  11   . 
     The gas source G 61  is a TiCl 4  gas source and is connected to the gas supply path  6  via the gas line L 61 . The gas line L 61  is provided with a mass flow controller M 61 , a storage tank T 61 , and a valve V 61  sequentially from a side of the gas source G 61 . The mass flow controller M 61  controls a flow rate of TiCl 4  gas flowing through the gas line L 61 . With the valve V 61  closed, the storage tank T 61  can store the TiCl 4  gas supplied from the gas source G 61  via the gas line L 61 , and increase a pressure of the TiCl 4  gas in the storage tank T 61 . The valve V 61  performs a supply and stop of the TiCl 4  gas to the gas supply path  6  by an opening/closing operation. 
     The gas source G 62  is an Ar gas source and is connected to the gas supply path  6  via the gas line L 62 . The gas line L 62  is provided with a mass flow controller M 62  and a valve V 62  sequentially from a side of the gas source G 62 . The mass flow controller M 62  controls a flow rate of Ar gas flowing through the gas line L 62 . The valve V 62  performs a supply and stop of the Ar gas to the gas supply path  6  by an opening/closing operation. 
     The gas source G 63  is an O 2  gas source and is connected to the gas supply path  6  via the gas line L 63 . The gas line L 63  is provided with a mass flow controller M 63  and a valve V 63  sequentially from a side of the gas source G 63 . The mass flow controller M 63  controls a flow rate of O 2  gas flowing through the gas line L 63 . The valve V 63  performs a supply and stop of the O 2  gas to the gas supply path  6  by an opening/closing operation. 
     The film forming apparatus  1  includes the controller  100  and a storage  101 . The controller  100  includes a CPU, a RAM, a ROM, and the like, (none of which are shown), and comprehensively controls the film forming apparatus  1  by causing the CPU to execute a computer program stored in the ROM or the storage  101 , for example. Specifically, the controller  100  causes the CPU to execute a control program stored in the storage  101  to control operations of respective components of the film forming apparatus  1 , thereby performing a film forming process and the like on the substrate W. 
     Next, an operation of the film forming apparatus  1  will be described with reference back to  FIG.  11   . First, the controller  100  opens the gate valve  26 , transfers the substrate W into the process container  2  by a transfer mechanism, and places the substrate W on the stage  3 . The substrate W is placed horizontally with the surface Wa facing upward. The controller  100  retracts the transfer mechanism from the process container  2  and then closes the gate valve  26 . Subsequently, the controller  100  heats the substrate W to a predetermined temperature by the heating mechanism  34  of the stage  3  and adjusts the interior of the process container  2  to a predetermined pressure by the pressure regulator  23 . For example, step S 101  in  FIG.  1    includes loading the substrate W into the process container  2 , and the like. 
     Subsequently, the controller  100  performs step S 102  of  FIG.  1   . In step S 102 , the valves V 61 , V 62 , and V 63  are opened to supply the TiCl 4  gas, the Ar gas, and the O 2  gas, respectively, into the process container  2  at the same time. 
     Specific process conditions of step S 102  are, for example, as follows. 
     Flow rate of the TiCl 4  gas: 1 sccm to 500 sccm 
     Flow rate of the Ar gas: 100 sccm to 100,000 sccm 
     Flow rate of the O 2  gas: 100 sccm to 100,000 sccm 
     Processing time: 0.1 second to 30 seconds 
     Processing temperature: 100 degrees C. to 450 degrees C. 
     Processing pressure: 3 Pa to 10,000 Pa 
     Subsequently, the controller  100  performs step S 103  of  FIG.  1   . In step S 103 , the valve V 61  is closed. At this time, since the valves V 62  and V 63  are opened, the Ar gas and the O 2  gas are supplied into the process container  2 , and the TiCl 4  gas remaining in the process container  2  is discharged to the exhaust pipe  22 . 
     Specific process conditions of step S 103  are, for example, as follows. 
     Flow rate of the Ar gas: 100 sccm to 100,000 sccm 
     Flow rate of the O 2  gas: 100 sccm to 100,000 sccm 
     Processing time: 0.1 second to 30 seconds 
     Processing temperature: 100 degrees C. to 450 degrees C. 
     Processing pressure: 3 Pa to 10,000 Pa 
     Subsequently, the controller  100  performs step S 104  of  FIG.  1   . In step S 104 , plasma is generated by the plasma generator  51  to plasmarize the O 2  gas. As a result, the adsorbed TiCl 4  gas is oxidized to form, for example, a TiO film. The TiO film is selectively formed on the second film W 2  with respect to the first film W 1 . Specific process conditions of step S 104  are the same as the process conditions of step S 103 , except for the generation of plasma, and thus explanation thereof will be omitted. 
     Subsequently, the controller  100  performs step S 105  of  FIG.  1   . In step S 105 , the generation of plasma is stopped. At this time, since the valves V 62  and V 63  are opened, the Ar gas and the O 2  gas are supplied into the process container  2 , and the plasmarized gas remaining in the process container  2  is discharged to the exhaust pipe  22 . Specific process conditions of step S 105  are the same as the process conditions of step S 103 , and thus explanation thereof will be omitted. 
     Subsequently, in step S 106  of  FIG.  1   , the controller  100  determines whether or not steps S 102  to S 105  have been performed N times (N is a natural number of one or more). When the execution number of steps S 102  to S 105  is less than N times (“NO” in step S 106 ), the controller  100  performs steps S 102  to S 105  again. On the other hand, when the execution number of steps S 102  to S 105  reaches N times (“YES” in step S 106 ), the controller  100  ends the current process. Thereafter, the controller  100  opens the gate valve  26  and transfers the substrate W out of the process container  2  by the transfer mechanism. The controller  100  retracts the transfer mechanism from the process container  2  and then closes the gate valve  26 . 
     In addition, the controller  100  may perform steps S 201  to S 205  shown in  FIG.  9   . In addition, the controller  100  may perform the series of processes shown in  FIG.  20   . The series of processes includes performing steps S 201  to S 204  M times (M is an integer of one or more) and performing steps S 102  to S 105  N times (N is an integer of one or more). The controller  100  performs the series of processes K times (K is an integer of one or more). 
     Although steps S 102  to S 105  are performed N times in  FIG.  1   , steps S 102 A and S 103 A may be performed after step S 103  and before step S 104 , as shown in Table 12, which will be described later. Step S 102 A is performed in the same manner as step S 102  except that a raw material gas different from that in step S 102  is used. Step S 103 A is performed in the same manner as step S 103 . 
     As shown in Table 12 which will be described later, by repeatedly performing supplying a raw material gas containing an element X 1  as the element X, supplying a raw material gas containing an element X 2 , which is different from the element X 1 , as the element X, and supplying a plasmarized reaction gas, the third film W 3 , which is an oxide film of the element X (specifically, the elements X 1  and X 2 ), may be selectively formed on the second film W 2  with respect to the first film W 1 . One of the element X 1  and the element X 2  is a metal element (specifically, a transition metal element) and the other one is a semiconductor element. By performing both steps S 102  and S 102 A, crystallization of the third film W 3  can be suppressed, so that flatness of the third film W 3  can be improved. 
     Although the element X 1  is a metal element and the element X 2  is a semiconductor element in Table 12, the element X 1  may be a semiconductor element and the element X 2  may be a metal element. Further, the combination of the element X 1  and the element X 2  may be a combination of metal elements or a combination of semiconductor elements. The element X may include an element X 3  different from the elements X 1  and X 2 , or may include three or more elements different from one another. The controller  100  may also supply a raw material gas containing the element X 3 . 
     Further, as shown in Table 13 which will be described later, steps S 102 A to S 105 A may be performed after performing steps S 102  to S 105  n times (n is any natural number from one to N) and before performing steps S 102  to S 105  (n+1) times. Step S 102 A is performed in the same manner as step S 102  except that a raw material gas different from that in step S 102  is used. Steps S 103 A to S 105 A are performed in the same manner as steps S 103  to S 105 , respectively. 
     As shown in Table 13 which will be described later, by repeatedly performing supplying a raw material gas containing an element X 1  as the element X, supplying a plasmarized reaction gas, supplying a raw material gas containing an element X 2 , which is different from the element X 1 , as the element X, and supplying a plasmarized reaction gas, the third film W 3 , which is an oxide film of the element X (specifically, the elements X 1  and X 2 ), may be selectively formed on the second film W 2  with respect to the first film W 1 . One of the element X 1  and the element X 2  is a metal element (specifically a transition metal element) and the other one is a semiconductor element. By performing both steps S 102  and S 102 A, crystallization of the third film W 3  can be suppressed, so that flatness of the third film W 3  can be improved. 
     Although the element X 1  is a metal element and the element X 2  is a semiconductor element in Table 13, the element X 1  may be a semiconductor element and the element X 2  may be a metal element. Further, the combination of the element X 1  and the element X 2  may be a combination of metal elements or a combination of semiconductor elements. The element X may include an element X 3  different from the elements X 1  and X 2 , or may include three or more elements different from one another. The controller  100  may also supply a raw material gas containing the element X 3 . 
     Examples 
     Next, Examples and the like will be described. Cases 1, 5, and 9 to 17 to be described below are Examples, and Cases 2 to 4 and 6 to 8 to be described below are Comparative Examples. 
     [Case 1] 
     In Case 1, a substrate having a surface of a B film W 1 - 1  and a surface of a SiO film W 2 - 1  on the same plane, as shown in  FIG.  12   , was prepared, and steps S 102  to S 105  of  FIG.  1    were performed under process conditions shown in Table 1. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 N 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Case 1 
                 S102 
                 0.5 
                 TiCl 4  + Ar + O 2   
                 OFF 
                 350 
                 200 
               
               
                   
                 S103 
                 1.0 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S104 
                 0.4 
                 Ar + O 2   
                 ON 
               
               
                   
                 S105 
                 0.1 
                 Ar + O 2   
                 OFF 
               
               
                   
               
            
           
         
       
     
     In Table 1, “ON” of “RF” means a gas was plasmarized by radio frequency power. “OFF” of “RF” means not plasmarizing a gas. The same applies to Tables 2, 3, 5, 7, 8, and 10 to 16 to be described below. 
     As shown in Table 1, in Case 1, TiCl 4  gas and plasmarized O 2  gas were alternately supplied to the substrate surface by a plasma ALD method. As a result, as shown in  FIG.  13   , a TiO film W 3 - 1  was selectively formed on the SiO film W 2 - 1  with respect to the B film W 1 - 1 . 
     [Cases 2 to 4] 
     In Cases 2 to 4, substrates having the same structure as in  FIG.  12    were prepared and TiO films were formed by a thermal ALD, a thermal CVD method, and a plasma CVD method, respectively, but in all Cases 2 to 4, the TiO films were formed over the entire substrate surfaces. 
     In Case 2, the substrate heated to 350 degrees C. was alternately supplied with TiCl 4  gas and non-plasmarized H 2 O gas 300 times each by the thermal ALD method. 
     In Case 3, the substrate heated to 350 degrees C. was simultaneously supplied with TiCl 4  gas and non-plasmarized O 3  gas) by the thermal CVD method. 
     In Case 4, the substrate heated to 350 degrees C. was simultaneously supplied with TiCl 4  gas and plasmarized O 2  gas by the plasma CVD method. 
     Comparing Case 1 with Cases 2 to 4, it can be recognized that it is important to use a plasma ALD method in order to selectively form a TiO film on a SiO film with respect to a B film. 
     [Case 5] 
     In Case 5, a substrate having a surface of a BN film W 1 - 5  and a surface of a SiO film W 2 - 5  on the same plane was prepared, as shown in  FIG.  33   , and a process of  FIG.  32    was performed under process conditions shown in Table 2. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 N 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Case 5 
                 S102 
                 2 
                 TiCl 4  + Ar 
                 OFF 
                 400 
                 300 
               
               
                   
                 S103 
                 1 
                 Ar 
                 OFF 
               
               
                   
                 S109 
                 5 
                 O 3  + O 2  + Ar + N 2   
                 OFF 
               
               
                   
                 S105 
                 1 
                 Ar 
                 OFF 
               
               
                   
               
            
           
         
       
     
     As shown in Table 2, in Case 5, the substrate surface heated to 400 degrees C. was alternately supplied with TiCl 4  gas and non-plasmarized O 3  gas) 300 times each by a thermal ALD method. As a result, as shown in  FIG.  34   , a TiO film W 3 - 5  was selectively formed on the SiO film W 2 - 5  with respect to the BN film W 1 - 5 . 
     [Cases 6 to 8] 
     In Case 6, a substrate having the same structure as in  FIG.  12    was prepared and a Ti film was formed by a plasma ALD method, but the Ti film was formed over the entire substrate surface. In the plasma ALD method of Case 6, the substrate heated to 350 degrees C. was alternately supplied with TiCl 4  gas and plasmarized H 2  gas. 
     In Case 7, a substrate having the same structure as in  FIG.  12    was prepared and a TiN film was formed by a plasma ALD method, but the TiN film was formed over the entire substrate surface. In the plasma ALD method of Case 7, the substrate heated to 350 degrees C. was alternately supplied with TiCl 4  gas and plasmarized NH 3  gas. 
     In Case 8, a substrate having the same structure as in  FIG.  12    was prepared and a TiN film was formed by a thermal ALD method, but the TiN film was formed over the entire substrate surface. In the plasma ALD method of Case 8, the substrate heated to 250° C. was alternately supplied with TDMAT (Ti[N(CH 3 ) 2 ] 4 ) gas and non-plasmarized NH 3  gas. 
     Comparing Case 1 with Cases 6 to 8, it can be recognized that it is important to plasmarize a reaction gas containing oxygen and form an oxide film in order to selectively form a Ti-containing film on a SiO film with respect to a B film. 
     [Case 9] 
     In Case 9, as shown in  FIG.  14   , a substrate in which recesses were formed in portions of a surface of a B film W 1 - 9  and a SiO film W 2 - 9  was exposed only on bottom surfaces of the recesses was prepared, and steps S 102  to S 105  of  FIG.  1    were performed under process conditions shown in Table 3. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 N 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Case 9 
                 S102 
                 0.5 
                 TiCl 4  + Ar + O 2   
                 OFF 
                 350 
                 1,000 
               
               
                   
                 S103 
                 1.0 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S104 
                 0.4 
                 Ar + O 2   
                 ON 
               
               
                   
                 S105 
                 0.1 
                 Ar + O 2   
                 OFF 
               
               
                   
               
            
           
         
       
     
     As shown in Table 3, in Case 9, TiCl 4  gas and plasmarized O 2  gas were alternately supplied to the substrate surface. As a result, as shown in  FIG.  15   , the inside of the recesses of the B film W 1 - 9  were selectively filled with a TiO film W 3 - 9 . 
     [Case 10] 
     In Case 10, steps S 102  to S 105  of  FIG.  1    were performed under process conditions shown in Table 5 with respect to various base films shown in Table 4. Thereafter, thicknesses of TiO films formed on the various base films were measured. Table 4 shows the measurement results of the thicknesses. In Table 4, “c-Si” is crystallized silicon. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                   
                 Thickness of third 
               
               
                   
                 Base film 
                 film (TiO film) [nm] 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 B 
                 0.0 
               
               
                   
                 BN 
                 0.0 
               
               
                   
                 c-Si 
                 13.2 
               
               
                   
                 SiO 2   
                 13.9 
               
               
                   
                 SiN 
                 13.2 
               
               
                   
                 Al 2 O 3   
                 23.8 
               
               
                   
                 W 
                 21.8 
               
               
                   
                 TiN 
                 13.4 
               
               
                   
                 Mo 
                 12.1 
               
               
                   
                 Ru 
                 16.9 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 5 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 N 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Case 10 
                 S102 
                 0.5 
                 TiCl 4  + Ar + O 2   
                 OFF 
                 300 
                 300 
               
               
                   
                 S103 
                 1.0 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S104 
                 0.4 
                 Ar + O 2   
                 ON 
               
               
                   
                 S105 
                 0.1 
                 Ar + O 2   
                 OFF 
               
               
                   
               
            
           
         
       
     
     As is clear from Table 4, no TiO film was formed on the B-containing films, whereas the TiO film was formed on the films containing substantially no B. A similar tendency was observed under process conditions in which N in step S 106  exceeded 1,000 times. 
     [Case 11] 
     In Case 11, steps S 201  to S 205  of  FIG.  9    were performed under process conditions shown in Table 7 with respect to various base films shown in Table 6, and then steps S 102  to S 106  of  FIG.  1    were performed under process conditions shown in Table 8. Thereafter, thicknesses of third films (TiO films) formed on the various base films were measured. Table 6 shows the measurement results of the thicknesses. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 6 
               
               
                   
                   
               
               
                   
                   
                 Thickness of third 
               
               
                   
                 Base film 
                 film (TiO film) [nm] 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 SiO 2   
                 14.6 
               
               
                   
                 TiO 2   
                 0.0 
               
               
                   
                 Mo 
                 19.5 
               
               
                   
                 Ru 
                 0.0 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 7 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 M 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Case 11 
                 S201 
                 0.5 
                 TDMAB + Ar + 
                 OFF 
                 130 
                 300 
               
               
                   
                   
                   
                 NH 3   
               
               
                   
                 S202 
                 1.0 
                 Ar + NH 3   
                 OFF 
               
               
                   
                 S203 
                 2.0 
                 Ar + NH 3   
                 ON 
               
               
                   
                 S204 
                 0.1 
                 Ar + NH 3   
                 OFF 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 8 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 N 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Case 11 
                 S102 
                 0.5 
                 TiCl 4  + Ar + O 2   
                 OFF 
                 350 
                 300 
               
               
                   
                 S103 
                 1.0 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S104 
                 0.4 
                 Ar + O 2   
                 ON 
               
               
                   
                 S105 
                 0.1 
                 Ar + O 2   
                 OFF 
               
               
                   
               
            
           
         
       
     
     As is clear from Table 6, no third film (TiO film) was formed on the TiO 2  film and the Ru film, whereas the third film (TiO film) was formed on the SiO 2  film and the Mo film. Comparing Tables 4 and 6, it is thought that a BN film was formed on the TiO 2  film and the Ru film, and no BN film was formed on the SiO 2  film and the Mo film. A similar tendency was observed under process conditions in which N in step S 106  exceeded 1,000 times. 
     [Case 12] 
     In Case 12, steps S 201  to S 205  of  FIG.  9    were performed under process conditions shown in Table 10 with respect to various base films shown in Table 9, and then steps S 102  to S 106  of  FIG.  1    were performed under process conditions shown in Table 11. Thereafter, thicknesses of third films (TiO films) formed on the various base films were measured. Table 9 shows the measurement results of the thicknesses. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 9 
               
               
                   
                   
               
               
                   
                   
                 Thickness of third 
               
               
                   
                 Base film 
                 film (TiO film) [nm] 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 SiO 2   
                 0.0 
               
               
                   
                 TiO 2   
                 17.8 
               
               
                   
                 Mo 
                 20.3 
               
               
                   
                 Ru 
                 10.0 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 10 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 M 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Case 12 
                 S201 
                 0.5 
                 TDMAB + Ar + 
                 OFF 
                 170 
                 300 
               
               
                   
                   
                   
                 N 2  + H 2   
               
               
                   
                 S202 
                 1.0 
                 Ar + N 2  + H 2   
                 OFF 
               
               
                   
                 S203 
                 2.0 
                 Ar + N 2  + H 2   
                 ON 
               
               
                   
                 S204 
                 0.1 
                 Ar + N 2  + H 2   
                 OFF 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 11 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 N 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Case 12 
                 S102 
                 0.5 
                 TiCl 4  + Ar + O 2   
                 OFF 
                 350 
                 300 
               
               
                   
                 S103 
                 1.0 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S104 
                 0.4 
                 Ar + O 2   
                 ON 
               
               
                   
                 S105 
                 0.1 
                 Ar + O 2   
                 OFF 
               
               
                   
               
            
           
         
       
     
     As is clear from Table 9, no third film (TiO film) was formed on the SiO 2  film, whereas the third film (TiO film) was formed on the TiO 2  film, the Mo film, and the Ru film. Comparing Tables 4 and 9, it is thought that a BN film was formed on the SiO 2  film, and no BN film was formed on the TiO 2  film, the Mo film, and the Ru film. A similar tendency was observed under process conditions in which N in step S 106  exceeded 1,000 times. It is thought that the reason why the film type of the base film on which the BN film is formed is different between Case 11 and Case 12 is mainly because the type of gas plasmarized in step S 203  is different. In step S 203  of Case 11, NH 3  gas was used as shown in Table 7, whereas in step S 203  of Case 12, a mixture of N 2  gas and H 2  gas was used as shown in Table 10. 
     [Case 13] 
     In Case 13, as shown in  FIG.  16   , a substrate having a surface of a B film W 1 - 13  and a surface of a SiO film W 2 - 13  on the same plane was prepared, and steps S 102  to S 105  of  FIG.  1    were performed under process conditions shown in Table 12. Further, in Case 13, as shown in Table 12, steps S 102 A and S 103 A were performed after step S 103  and before step S 104 . 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 12 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 N 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Case 13 
                 S102 
                 0.5 
                 TiCl 4  + Ar + O 2   
                 OFF 
                 350 
                 300 
               
               
                   
                 S103 
                 1.0 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S102A 
                 0.5 
                 SiCl 4  + Ar + O 2   
                 OFF 
               
               
                   
                 S103A 
                 1.0 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S104 
                 0.4 
                 Ar + O 2   
                 ON 
               
               
                   
                 S105 
                 0.1 
                 Ar + O 2   
                 OFF 
               
               
                   
               
            
           
         
       
     
     As shown in Table 12, in Case 13, TiCl 4  gas, SiCl 4  gas, and plasmarized O 2  gas were supplied to the substrate surface sequentially with repetition of N (N=300) times by a plasma ALD method. As a result, as shown in  FIG.  17   , a TiSiO film W 3 - 13  was selectively formed on the SiO film W 2 - 13  with respect to the B film W 1 - 13 . 
     [Case 14] 
     In Case 14, as shown in  FIG.  18   , a substrate having a surface of a B film W 1 - 14  and a surface of a SiO film W 2 - 14  on the same plane was prepared, and steps S 102  to S 105  of  FIG.  1    were performed under process conditions shown in Table 13. Further, in Case 14, as shown in Table 13, step S 102 A to S 105 A were performed after steps S 102  to S 105  were performed n times (n is any natural number from one to N) and before steps S 102  to S 105  were performed (n+1) times. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 13 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 N 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Case 14 
                 S102 
                 0.5 
                 TiCl 4  + Ar + O 2   
                 OFF 
                 350 
                 300 
               
               
                   
                 S103 
                 1.0 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S104 
                 0.4 
                 Ar + O 2   
                 ON 
               
               
                   
                 S105 
                 0.1 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S102A 
                 0.5 
                 SiCl 4  + Ar + O 2   
                 OFF 
               
               
                   
                 S103A 
                 1.0 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S104A 
                 0.4 
                 Ar + O 2   
                 ON 
               
               
                   
                 S105A 
                 0.1 
                 Ar + O 2   
                 OFF 
               
               
                   
               
            
           
         
       
     
     As shown in Table 13, in Case 14, TiCl 4  gas, plasmarized O 2  gas, SiCl 4  gas, and plasmarized O 2  gas were supplied to the substrate surface sequentially with repetition of N (N=300) times by a plasma ALD method. As a result, as shown in  FIG.  19   , a TiSiO film W 3 - 14  was selectively formed on the SiO film W 2 - 14  with respect to the B film W 1 - 14 . 
     [Case 15] 
     In Case 15, as shown in  FIG.  26   , a substrate having a surface of a B film W 1 - 15  and a surface of a SiO film W 2 - 15  on the same plane was prepared, and steps S 102  to S 105  of  FIG.  1    were performed under process conditions shown in Table 14. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 14 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 M 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Case 15 
                 S102 
                 5 
                 Si 2 Cl 6  + Ar 
                 OFF 
                 300 
                 300 
               
               
                   
                 S103 
                 6 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S104 
                 1 
                 Ar + O 2   
                 ON 
               
               
                   
                 S105 
                 6 
                 Ar 
                 OFF 
               
               
                   
               
            
           
         
       
     
     As shown in Table 14, in Case 15, Si 2 Cl 6  gas and plasmarized O 2  gas were alternately supplied to the substrate surface by a plasma ALD method. As a result, as shown in  FIG.  27   , a SiO film W 3 - 15  was selectively formed on the SiO film W 2 - 15  with respect to the B film W 1 - 15 . 
     [Case 16] 
     In Case 16, as shown in  FIG.  28   , a substrate having a surface of a Ru film W 4 - 16  and a surface of a SiO film W 2 - 16  on the same plane was prepared, and steps S 201 , S 203 , S 204 , and S 102  to S 105  of  FIG.  20    were performed under process conditions shown in Table 15. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 15 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 M, N, K 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Case 16 
                 S201 
                 1.0 
                 TDMAB + Ar + NH 3   
                 OFF 
                 300 
                 M = 1 
                 K = 1 
               
               
                   
                 S203 
                 10 
                 TDMAB + Ar + NH 3   
                 ON 
               
               
                   
                 S204 
                 50 
                 Ar 
                 OFF 
               
               
                   
                 S102 
                 0.5 
                 TiCl 4  + Ar + O 2   
                 OFF 
                 300 
                 N = 300 
               
               
                   
                 S103 
                 1.0 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S104 
                 0.4 
                 Ar + O 2   
                 ON 
               
               
                   
                 S105 
                 0.1 
                 Ar + O 2   
                 OFF 
               
               
                   
               
            
           
         
       
     
     As a result, in Case 16, as shown in  FIG.  29   , a TiO film W 3 - 16  was selectively formed on the SiO film W 2 - 16  with respect to the Ru film W 4 - 16 . It is thought that the reason is because a BN film was formed on the Ru film W 4 - 16  and no BN film was formed on the SiO film W 2 - 16 . The results of Case 16 are consistent with the results of Case 11 (see Table 6). 
     [Case 17] 
     In Case 17, as shown in  FIG.  30   , a substrate having a surface of a Ru film W 4 - 17  and a surface of a SiO film W 2 - 17  on the same plane was prepared, and steps S 201  to S 204  and S 102  to S 105  of  FIG.  20    were performed under process conditions shown in Table 16. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                   
                 TABLE 16 
               
               
                   
                   
               
               
                   
                   
                 Time 
                   
                   
                 Temperature 
                   
               
               
                   
                 Step 
                 [sec] 
                 Supplied gas 
                 RF 
                 [degrees C.] 
                 M, N, K 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Case 17 
                 S201 
                 1.0 
                 TDMAB + Ar + H 2   
                 OFF 
                 200 
                 M = 1 
                 K = 300 
               
               
                   
                 S202 
                 1.0 
                 Ar + H 2   
                 OFF 
               
               
                   
                 S203 
                 1.0 
                 Ar + H 2   
                 ON 
               
               
                   
                 S204 
                 0.1 
                 Ar + H 2   
                 OFF 
               
               
                   
                 S102 
                 0.5 
                 TiCl 4  + Ar + O 2   
                 OFF 
                 200 
                 N = 1 
               
               
                   
                 S103 
                 1.0 
                 Ar + O 2   
                 OFF 
               
               
                   
                 S104 
                 0.4 
                 Ar + O 2   
                 ON 
               
               
                   
                 S105 
                 0.1 
                 Ar + O 2   
                 OFF 
               
               
                   
               
            
           
         
       
     
     As a result, in Case 17, as shown in  FIG.  31   , a TiO film W 3 - 17  was selectively formed on the SiO film W 2 - 17  with respect to the Ru film W 4 - 17 . It is thought that the reason is because a B film was formed on the Ru film W 4 - 17  and no B film was formed on the SiO film W 2 - 17 . 
     According to the present disclosure in some embodiments, it is possible to selectively form an oxide film on a second film, which is made of a material different from that of a first film containing boron, with respect to the first film. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosures. Indeed, the embodiments described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures.