Film formation method and film formation device

Abstract

A film formation method according to the present invention comprises: preparing a substrate that has, in different regions on the surface thereof, an oxide film which contains substantially no boron and a non-oxide film which contains substantially no oxygen; supplying a modification gas containing boron to the substrate so as to modify at least the surface of the oxide film into a boron oxide film; and forming a target film selectively on the surface of the non-oxide film with respect to the surface of the boron oxide film. The target film contains a desired element X. The forming a target film includes supplying, to the substrate, a raw material gas that contains a compound of halogen and the element X and a reaction gas that reacts with an adsorbate of the raw material gas.

Description

Film forming method and film forming apparatus

[0001] The present disclosure relates to a film formation method and a film formation apparatus.

[0002] The film formation method described in Patent Document 1 uses a boron-containing film as an inhibitor film that inhibits the formation of a target film in order to selectively form the target film on a portion of the substrate surface. On the other hand, the film formation method described in Patent Document 2 uses a self-assembled monolayer (SAM) as an inhibitor film that inhibits the formation of a target film in order to selectively form the target film on a portion of the substrate surface. In Patent Document 2, before forming the SAM, an oxide film is replaced with a boron oxide film, and the boron oxide film is removed to remove unnecessary SAM adhering to the boron oxide film. In other words, in Patent Document 2, the boron oxide film is used not as an inhibitor film but to remove the inhibitor film.

[0003] Japanese Patent Publication No. 2023-068619 Japanese Patent Publication No. 2020-158805

[0004] One embodiment of the present disclosure provides a technique for forming, by a simple process, a boron oxide film to be used as an inhibiting film that inhibits the formation of a target film in selective film formation of the target film.

[0005] A film forming method according to one embodiment of the present disclosure includes: preparing a substrate having an oxide film substantially free of boron and a non-oxide film substantially free of oxygen in different surface regions; supplying a boron-containing modifying gas to the substrate to modify at least the surface of the oxide film into a boron oxide film; and selectively forming a target film on the surface of the non-oxide film relative to the surface of the boron oxide film. The target film contains a desired element X. Forming the target film includes supplying to the substrate a source gas containing a compound of the element X and a halogen, and a reactant gas that reacts with an adsorbate of the source gas.

[0006] According to an embodiment of the present disclosure, a boron oxide film to be used as an inhibiting film that inhibits the formation of a target film in selective film formation of the target film can be formed by a simple process.

[0007] FIG. 1 is a flowchart showing a film forming method according to an embodiment. FIG. 2 is a flowchart showing an example of S103 in FIG. 1 . FIG. 3 is a cross-sectional view showing a film forming method according to an embodiment. FIG. 4 is a flowchart showing a film forming method according to a modified example. FIG. 5 is a flowchart showing an example of S107 in FIG. 4 . FIG. 6 is a cross-sectional view showing a film forming method according to a modified example. FIG. 7 is a cross-sectional view showing a film forming method according to a modified example, subsequent to FIG. 6 . FIG. 8 is a cross-sectional view showing a modified example of S101 in FIG. 6 . FIG. 9 is a plan view showing a substrate processing apparatus according to an embodiment. FIG. 10 is a cross-sectional view showing an example of a first processing unit.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or similar components are denoted by the same reference numerals, and their description may be omitted. In the specification, the numerical range "to" means that the numerical values ​​before and after it are included as the lower and upper limits. The numerical range includes the range rounded up or down. In this specification, the semiconductor element is Si or Ge.

[0009] First, a film formation method according to one embodiment will be described with reference to Figures 1 to 3. The film formation method includes, for example, steps S101 to S106 shown in Figure 1. Note that the film formation method only needs to include steps S101 to S104, and does not necessarily need to include steps S105 to S106. Furthermore, the film formation method may include steps other than steps S101 to S106 shown in Figure 1.

[0010] Step S101 includes preparing a substrate W (see, for example, FIG. 3). The substrate W has an oxide film W1 containing oxygen and a non-oxide film W2 containing substantially no oxygen in different regions of its surface. The substrate W may be cleaned in advance so that both the oxide film W1 and the non-oxide film W2 are exposed in different regions of the surface of the substrate W. In this embodiment, the surface of the substrate W is flat, but may also be uneven. It is preferable that both the oxide film W1 and the non-oxide film W2 are substantially free of boron (B). "Substantially free of B" means that the B content is 0 at % to 5 at %.

[0011] The oxide film W1 contains, for example, a compound of a semiconductor element and oxygen, or a compound of a metal and oxygen. The oxide film W1 preferably has an oxygen content of 20 at% to 60 at%. The oxide film W1 is not particularly limited, but may be, for example, a SiO film, a TiO film, a SnO film, a WO film, or a HfO film. Here, the SiO film refers to a film containing silicon (Si) and oxygen (O). The atomic ratio of Si to O in the SiO film is not limited to 1:2. Films other than SiO films, such as TiO films, SnO films, WO films, and HfO films, also contain the respective elements and are not limited to stoichiometric ratios.

[0012] The non-oxide film W2 contains, for example, only a semiconductor element, a compound of a semiconductor element and nitrogen, only a metal, or a compound of a metal and nitrogen. The non-oxide film W2 preferably has an oxygen content of 0 at % to 10 at %. The non-oxide film W2 is not particularly limited, but may be, for example, a Si film, a SiN film, or a SiGe film. When the non-oxide film W2 is a semiconductor film, the semiconductor film may be any of an amorphous film, a polycrystalline film, and a single-crystalline film.

[0013] The oxide film W1 and the non-oxide film W2 are formed on an underlying substrate (not shown). The underlying substrate is a silicon wafer or a compound semiconductor wafer. The compound semiconductor wafer is, for example, a GaAs wafer, a SiC wafer, a GaN wafer, or an InP wafer. The underlying substrate may be a glass substrate. A functional film (not shown) may be formed between the oxide film W1 or the non-oxide film W2 and the underlying substrate (not shown). The oxide film W1 may be formed by naturally oxidizing a film (e.g., a metal film or a semiconductor film) directly below the oxide film W1 due to contact with the atmosphere. The oxide film W1 may be formed by oxidizing a film (e.g., a metal film or a semiconductor film) directly below the oxide film W1 due to reaction with a reactive gas or the like.

[0014] Step S102 includes modifying the surface of the oxide film W1 with a modifying gas to form a boron oxide film WA (see FIG. 3) so that the target film WB can be selectively formed in the desired region in step S103. The modifying gas selectively modifies the surface of the oxide film W1 to form a boron oxide film WA relative to the surface of the non-oxide film W2. The modifying gas contains boron, which removes oxygen from the oxide film W1 to form the boron oxide film WA. At this time, the semiconductor or metal elements contained in the oxide film W1 become volatile compounds and are desorbed from the surface of the oxide film W1. As a result, a highly pure boron oxide film WA is formed. The surface of the non-oxide film W2 is barely modified.

[0015] The modifying gas contains boron and modifies at least the surface of the oxide film W1 into a boron oxide film WA. ３ , B(CH ３ ) ３ , B ２ H ６ , B.F. ３ , BBr ３ , B.I. ３ , C ９ H ２４ BN ３ , C ３ H ９ B, C ６ H １５ B and B ３ N ３ H ６ It is preferable to include at least one of the following.

[0016] The oxide film W1 is a TiO film, and the modifying gas is BCl ３ In the case of a gas, a reforming reaction represented by the following reaction formula (1) proceeds: (1) TiO ２ +4 / 3BC1 ３ (g) → 2 / 3B ２ O ３ + TiCl ４ (g) The change in Gibbs energy in the reforming reaction represented by the above reaction formula (1) is −27.0 kcal / mol at 100° C.

[0017] The oxide film W1 is a SiO film, and the modifying gas is BCl ３In the case of gas, the reforming reaction represented by the following reaction formula (2) proceeds: (2) SiO ２ +4 / 3BC1 ３ (g) → 2 / 3B ２ O ３ +SiCl ４ (g) The change in Gibbs energy in the reforming reaction represented by the above reaction formula (2) is −9.8 kcal / mol at 100° C.

[0018] The oxide film W1 is a SnO film, and the modifying gas is BCl ３ In the case of a gas, a reforming reaction represented by the following reaction formula (3) proceeds: (3) SnO ２ +4 / 3BC1 ３ (g) → 2 / 3B ２ O ３ + SnCl ４ (g) The change in Gibbs energy in the reforming reaction represented by the above reaction formula (3) is −46.2 kcal / mol at 100° C.

[0019] The oxide film W1 is a WO film, and the modifying gas is BCl ３ When the WO gas is used, the reforming reaction represented by the following reaction formula (4) proceeds: ３ +2BC1 ３ (g) → B ２ O ３ +WC1 ６ (g) The change in Gibbs energy in the reforming reaction represented by the above reaction formula (4) is −13.3 kcal / mol at 100° C.

[0020] The oxide film W1 is a HfO film, and the modifying gas is BCl ３ In the case of HfO gas, the reforming reaction represented by the following reaction formula (5) proceeds: ２ +4 / 3BC1 ３ (g) → 2 / 3B ２ O ３ + HfCl ４ (g) The change in Gibbs energy in the reforming reaction represented by the above reaction formula (5) is −16.4 kcal / mol at 100° C.

[0021] The oxide film W1 is a SnO film, and the modifying gas is B(CH３ ) ３ In the case of a gas, a reforming reaction represented by the following reaction formula (6) proceeds: (6) SnO ２ +4 / 3B (CH ３ ) ３ (g) → 2 / 3B ２ O ３ + Sn(CH ３ ) ４ (g) The change in Gibbs energy in the reforming reaction represented by the above reaction formula (6) is −28.2 kcal / mol at 100° C.

[0022] The oxide film W1 is a SnO film, and the modifying gas is B (C ２ H ５ ) ３ In the case of a gas, a reforming reaction represented by the following reaction formula (7) proceeds: (7) SnO ２ +4 / 3B (C ２ H ５ ) ３ (g) → 2 / 3B ２ O ３ + Sn(C ２ H ５ ) ４ (g) The change in Gibbs energy in the reforming reaction represented by the above reaction formula (7) is −24.5 kcal / mol at 100° C.

[0023] The oxide film W1 is a SnO film, and the modifying gas is BBr ３ In the case of a gas, a reforming reaction represented by the following reaction formula (8) proceeds: (8) SnO ２ +4 / 3BBr ３ (g) → 2 / 3B ２ O ３ + SnBr ４ (g) The change in Gibbs energy in the reforming reaction represented by the above reaction formula (8) is −72.1 kcal / mol at 100° C.

[0024] The oxide film W1 is a SnO film, and the reforming gas is BI ３ In the case of a gas, a reforming reaction represented by the following reaction formula (9) proceeds: (9) SnO ２ +4 / 3BI ３ (g) → 2 / 3B ２ O ３+ SnI ４ (g) The change in Gibbs energy in the reforming reaction represented by the above reaction formula (9) is −113.4 kcal / mol at 100° C.

[0025] The more negative the change in Gibbs energy is and the larger its absolute value, the more likely the reforming reaction will proceed. To promote the reforming, the reformed gas may be converted into plasma. Note that the above-mentioned values ​​of the change in Gibbs energy are values ​​when the reformed gas is not converted into plasma.

[0026] In step S102, the temperature of the substrate W may be controlled to 100°C or higher to promote the reaction of the modifying gas on the surface of the oxide film W1 and promote the desorption of volatile compounds (e.g., metal compounds) produced as by-products by the modification. If the temperature of the substrate W is lower than 100°C, the reaction of the modifying gas does not occur sufficiently and the desorption of compounds (e.g., metal compounds) is insufficient, making it difficult to selectively form the boron oxide film WA. The temperature of the substrate W is preferably 200°C or higher. The temperature of the substrate W is preferably 800°C or lower.

[0027] The boron oxide film WA is used as an inhibitor film that inhibits the formation of the target film WB. Alternatively, selectively adsorbing an inhibitor onto the surface of the oxide film W1 may be considered as a method for selectively forming an inhibitor film on the surface of the oxide film W1. However, the selectivity of the adsorption reaction may be insufficient. In this embodiment, the selectivity of the reforming reaction is utilized, so that the inhibitor film can be formed only on the surface of the oxide film W1, and the target film WB can be selectively formed on the surface of the non-oxide film W2.

[0028] Step S103 includes selectively forming a target film WB on the surface of the non-oxide film W2 relative to the surface of the oxide film W1 modified into the boron oxide film WA in step S102 (see FIG. 3). Step S103 includes supplying to the substrate W a source gas containing a compound of a desired element X and a halogen, and a reactive gas that reacts with an adsorbate of the source gas. The source gas and the reactive gas are supplied alternately or simultaneously. In this case, the target film WB contains the element X.

[0029] 2, step S103 includes, for example, steps S103a to S103e. Note that step S103 may include at least steps S103a, S103c, and S103e, and does not necessarily include steps S103b and S103d. Steps S103a to S103e will be described below.

[0030] Step S103a includes supplying a source gas to the substrate W. The source gas contains a compound of an element X and a halogen. The halogen is fluorine, chlorine, bromine, or iodine. The element X is not particularly limited, but is preferably a metal element, more preferably a transition metal element. The element X is, for example, Ti, W, V, Al, Mo, Sn, Hf, Ta, Nb, Zr, In, Ga, or Sb. A specific example of the source gas is TiCl. ４ , WCl ６ , W.F. ６ , VCl ４ , AlCl ３ , MoCl ５ , SnCl ４ , HfCl ４ , TaCl ５ , NbCl ５ , ZrCl ４ , InCl ３ , GaCl ３ or SbCl ３ The element X may be a semiconductor element, specifically Si or Ge. The source gas is a silicon halide gas or a germanium halide gas. Specific examples of silicon halide gas include SiCl ４ , SiHCl ３ , SiH ２ Cl ２ , SiH ３ Cl, Si ２ Cl ６、 Si ２ HCl ５ , Si ２ Cl ３ CH ３ , SiCl ３ CCl ３ , SiCl ３ CH ３ , or SiH ２ I２ Specific examples of germanium halide gas include GeCl ４ The source gas may be supplied together with a dilution gas, such as Ar gas or N ２ It's gas.

[0031] Step S103b includes supplying a purge gas to the substrate W. The purge gas purges excess source gas that has not been adsorbed onto the substrate W in step S103a. The purge gas may be, for example, a rare gas such as Ar gas or N ２ A gas is used.

[0032] Step S103c includes supplying a reactive gas to the substrate W. The reactive gas reacts with an element X contained in the adsorbate of the source gas to form a target film WB. The target film WB contains the element X. Examples of the reactive gas include an oxygen-containing gas, a nitrogen-containing gas, and a hydrogen-containing gas. The oxygen-containing gas contains oxygen and forms an oxide film of the element X. The oxygen-containing gas is, for example, O ２ , O ３ , CO ２ , N ２ O, NO, or H ２ The nitrogen-containing gas contains nitrogen and forms a nitride film of element X. The nitrogen-containing gas is, for example, NH ３ , or N ２ H ４ The hydrogen-containing gas contains hydrogen and forms a film (for example, a metal film or a semiconductor film) containing element X as a main component. ２ , or H ２ The reactive gas may be supplied together with a diluent gas, such as Ar or N. ２ Includes.

[0033] Step S103c may include converting the reactive gas into plasma, or may include supplying the plasmatized reactive gas to the substrate W. Converting the reactive gas into plasma can promote the formation of the target film WB.

[0034] The reactive gas may be supplied not only in step S103c but also in all of steps S103a to S103d. However, the reactive gas is turned into plasma only in step S103c. This is because the reactive gas becomes more likely to react with adsorbates of the source gas on the substrate W when turned into plasma.

[0035] Step S103c uses O as a reactive gas. ３ may include supplying the gas to the substrate W without converting it into plasma.

[0036] Step S103d includes supplying a purge gas to the substrate W. The purge gas purges excess reactive gas that did not react with the substrate W in step S103c. The purge gas may be, for example, a rare gas such as Ar gas or N ２ A gas is used.

[0037] Step S103e includes checking whether the fourth cycle has been performed N times (N is an integer equal to or greater than 1). The fourth cycle includes steps S103a to S103d. N may be an integer equal to or greater than 2, and the fourth cycle may be repeatedly performed multiple times. This allows the film thickness of the target film WB to be increased.

[0038] If the fourth cycle has been performed less than N times (step S103e, NO), the film thickness of the target film WB is less than the target value, so the fourth cycle is performed again. N is preferably 200 or more, more preferably 300 or more. N is preferably 1000 or less.

[0039] On the other hand, if the number of times the fourth cycle has been performed reaches N (step S103e, YES), the film thickness of the target film WB has reached the target value, and therefore the current process ends.

[0040] 2 is an atomic layer deposition (ALD) method, but may be a chemical vapor deposition (CVD) method. In the ALD method, a source gas (step S103a) and a reactant gas (step S103c) are alternately supplied. In the CVD method, the source gas and the reactant gas are simultaneously supplied.

[0041] To inhibit the formation of the target film WB on the surface of the boron oxide film WA, it is important that the adsorption of the source gas to the boron oxide film WA is weak, and as a result, the adsorbed material of the source gas is desorbed on the surface of the boron oxide film WA without advancing the film formation reaction (formation of the target film WB). Alternatively, it is important that the source gas is not adsorbed on the surface of the boron oxide film WA, or that dissociation of the source gas is unlikely to occur on the surface of the boron oxide film WA. If dissociation of the source gas occurs, the substrate processing reaction is likely to proceed.

[0042] Since the boron oxide film WA contains boron, it is thought that adsorption of halides does not occur on the surface of the boron oxide film WA, or if it does occur, it is weak, or that dissociation of halides is difficult to occur, and as a result, the formation of the target film WB is inhibited on the surface of the boron oxide film WA.

[0043] On the other hand, since the non-oxide film W2 does not substantially contain boron, it is believed that halides are strongly adsorbed to the surface of the non-oxide film W2 or that halides are easily dissociated, which leads to the formation of the target film WB on the surface of the non-oxide film W2.

[0044] Also, TiCl ４ Halides such as Ti[N(CH ３ ) ２ ] ４ Compared to organometallic complexes such as those mentioned above, the source gas is less likely to decompose due to the heat of the substrate W. If the source gas decomposes after being adsorbed onto the boron oxide film WA, the formation of the target film WB will proceed. Therefore, in order to inhibit the formation of the target film WB on the surface of the boron oxide film WA, a gas containing a halogen is suitable as the source gas for the target film WB.

[0045] Furthermore, in the plasma CVD method in which both the halide and the reactive gas are converted into plasma, active species such as ions or radicals are generated when the halide dissociates. The active species generated from the halide are highly reactive, and it is thought that the substrate processing reaction is likely to proceed not only on the surface of the non-oxide film W2 but also on the surface of the boron oxide film WA. Therefore, it is preferable not to convert the source gas into plasma, and it is important to use the thermal ALD method, the plasma ALD method, or the thermal CVD method.

[0046] In the above steps S103a to S103d, the temperature of the substrate W may be controlled to 100°C or higher to promote desorption of the source gas from the surface of the boron oxide film WA. If the temperature of the substrate W is lower than 100°C, the source gas will not be sufficiently desorbed from the surface of the boron oxide film WA, resulting in physical adsorption of the source gas, and a target film WB will also be formed on the surface of the boron oxide film WA. The temperature of the substrate W is preferably 200°C or higher. The temperature of the substrate W is preferably 800°C or lower.

[0047] Step S104 includes checking whether the first cycle has been performed K times (K is an integer greater than or equal to 1). The first cycle includes supplying a modifying gas (step S102) and forming the target film WB (step S103). K may be an integer greater than or equal to 2, and the first cycle may be repeatedly performed multiple times. This allows the film thickness of the target film WB to be increased. In step S103, if damage to the boron oxide film WA progresses due to plasma or the like, and the surface of the oxide film W1 is exposed before the film thickness of the target film WB reaches the target value, it is effective to repeatedly perform the first cycle.

[0048] If the first cycle has been performed less than K times (step S104, NO), the film thickness of the target film WB is less than the target value, so the first cycle is performed again. K is preferably 1 or more, more preferably 2 or more. K is preferably 10 or less.

[0049] On the other hand, if the first cycle has been performed K times (YES in step S104), the film thickness of the target film WB has reached the target value, and step S105 is performed. Note that if K is an integer of 2 or greater, that is, if the first cycle is repeatedly performed, the target film WB is preferably a non-oxide film that does not substantially contain oxygen. The non-oxide film preferably has an oxygen content of 0 at% to 10 at%. If the target film WB is a non-oxide film, the modifying gas does not replace the target film WB with a boron oxide film WA in step S102 from the second time onward.

[0050] Step S105 includes etching the boron oxide film WA modified with the modifying gas with an etching gas (see FIG. 3). The etching gas is not particularly limited, but is preferably, for example, a rare gas plasma. The rare gas plasma sputters the boron oxide film WA and promotes its volatilization. As a result, etching of the boron oxide film WA progresses. The rare gas includes He, Ne, Ar, Kr, or Xe.

[0051] The etching gas is not limited to plasma of rare gas. ２ , O ２ , COS, N.H. ３ , S.O. ２ , CO ２ , CO, CH ４ , NO ２ , NO or N ２ The etching gas may contain Cl ２ , F ２ , HF, XeF ２ , ClF ３ , BrF ３ , HCl, Br ２ , HBr, I ２ , HI, SOCl ２ , S.O. ２ Cl ２ , or SF ６ The etching gas may also contain CF ４ , C.H. ３ F, CHF ３ , C ４ F ６ , C ４ F ８ , C.H.３ Cl, or CH ３ Br may be contained. These etching gases may be turned into plasma.

[0052] The etching gas etches the boron oxide film WA, thereby removing the target film WB that has adhered to the boron oxide film WA in step S103 and selectively leaving the target film WB on the non-oxide film W2. Note that the etching gas may etch not only the boron oxide film WA but also a portion of the target film WB formed on the non-oxide film W2.

[0053] Step S106 includes checking whether the second cycle has been performed L times (L is an integer greater than or equal to 1). The second cycle includes supplying a modifying gas (step S102), forming a target film WB (step S103), and supplying an etching gas (step S105). L may be an integer greater than or equal to 2, and the second cycle may be repeatedly performed multiple times. The film thickness of the target film WB can be increased while maintaining the selectivity of the target film WB.

[0054] If the number of times the second cycle has been performed is less than L (step S106, NO), the film thickness of the target film WB is less than the target value, so the second cycle is performed again. L is preferably 2 or more, more preferably 5 or more. L is preferably 10 or less.

[0055] On the other hand, if the number of times the second cycle has been performed reaches L (step S106, YES), the film thickness of the target film WB has reached the target value, and the process is terminated. Note that if L is an integer of 2 or greater, that is, if the second cycle is repeatedly performed, the target film WB is preferably a non-oxide film that does not substantially contain oxygen. The non-oxide film preferably has an oxygen content of 0 at% to 10 at%. If the target film WB is a non-oxide film, the modifying gas does not replace the target film WB with the boron oxide film WA in step S102 from the second time onwards.

[0056] As described above, the substrate processing method of this embodiment includes steps S101 to S103. Step S103 performs selective deposition of a target film WB. In the selective deposition of the target film WB, a boron oxide film WA is used as an inhibiting film that inhibits deposition of the target film WB. Step S102 supplies a modifying gas containing boron to the substrate W to modify the surface of the oxide film W1 into a boron oxide film WA. Thus, the boron oxide film WA can be formed by a simple process.

[0057] Furthermore, the substrate processing method of this embodiment includes step S105 in addition to steps S101 to S103. In step S105, the boron oxide film WA is etched with an etching gas. After the film thickness of the target film WB reaches a target value, the unnecessary boron oxide film WA can be removed. Furthermore, by removing the boron oxide film WA, the oxide film W1 is exposed, and a new boron oxide film WA can be formed on the oxide film W1.

[0058] In step S103, the target film WB is selectively formed on the non-oxide film W2 with respect to the boron oxide film WA. However, growth nuclei of the target film WB may also occur on the boron oxide film WA. Furthermore, a portion of the boron oxide film WA may be lost, exposing the surface of the oxide film W1. In other words, if step S103 takes a long time, the inhibitory properties of the boron oxide film WA may be impaired. By removing the boron oxide film WA in step S105 to expose the oxide film W1, and then forming the boron oxide film WA again on the oxide film W1 in step S103, the inhibitory properties of the boron oxide film WA can be restored.

[0059] Next, a film formation method according to a modified example will be described with reference to Figures 4 to 8. Differences from the above embodiment will be described below. The film formation method of the above embodiment uses a substrate W having an oxide film W1 and a non-oxide film W2 in different regions of its surface in order to form a boron oxide film WA on part of the substrate surface. The film formation method of this modified example uses a substrate W having, on the surface of the oxide film W1, convex top surfaces W1a and concave portions W1b recessed from the convex top surfaces W1a in order to form the boron oxide film WA on part of the substrate surface. As mentioned above, the surface of the substrate W in the above embodiment may be an uneven surface, and it is also possible to combine the above embodiment with this modified example.

[0060] The film formation method may include steps S101 to S109 shown in Fig. 4. The film formation method may include steps S101 to S104, and may not include steps S105 to S109. The film formation method may include steps other than steps S101 to S109 shown in Fig. 4.

[0061] Step S101 includes preparing a substrate W. The substrate W has, on the surface of an oxide film W1, a top surface W1a of a convex portion and a concave portion W1b recessed from the top surface W1a of the convex portion. The concave portion W1b has a side surface W1b1 and a bottom surface W1b2. In this modification, the formation of the concaves and convexes on the surface of the oxide film W1 is performed when the oxide film W1 is formed as shown in FIG. 6, but may also be performed after the oxide film W1 is formed as shown in FIG. 8. In the former case, the oxide film W1 is formed along the concaves and convexes of the base W0. The base W0 may be an oxide film.

[0062] Step S102 includes modifying the surface of the oxide film W1 with a modifying gas. The modifying gas selectively modifies the top surface W1a of the convex portion and its vicinity relative to the bottom surface W1b2 of the concave portion W1b and its vicinity. The modifying gas contains boron and modifies a portion of the oxide film W1 into a boron oxide film WA. The deeper the depth from the top surface W1a of the convex portion, the more difficult it is for the modifying gas to penetrate, and the more difficult it is for the boron oxide film WA to be formed. Almost no boron oxide film WA is formed on the bottom surface W1b2 of the concave portion W1b and its vicinity.

[0063] Step S103 includes selectively forming a target film WB on the bottom surface W1b2 of the recessed portion W1b and its vicinity, as well as on the top surface W1a of the convex portion modified into the boron oxide film WA in step S102 and its vicinity (see FIG. 6). Step S103 includes supplying to the substrate W a source gas containing a compound of a desired element X and a halogen, and a reactive gas that reacts with an adsorbate of the source gas. The source gas and the reactive gas are supplied alternately or simultaneously. In this case, the target film WB contains the element X. The target film WB is not particularly limited, but is preferably an oxide film having the same composition as the oxide film W1. Note that the target film WB does not have to be an oxide film, and may be a non-oxide film.

[0064] Step S104 includes checking whether the first cycle has been performed K times (K is an integer equal to or greater than 1). The first cycle includes supplying a modifying gas (step S102) and forming a target film WB (step S103). K may be an integer equal to or greater than 2, and the first cycle may be repeatedly performed multiple times. This allows the film thickness of the target film WB to be increased. In step S103, if damage to the boron oxide film WA progresses due to plasma or the like before the film thickness of the target film WB reaches a target value, and the surface of the oxide film W1 (the top surface W1a of the convex portion and its vicinity) is exposed, it is effective to repeatedly perform the first cycle.

[0065] When K in the first cycle is an integer equal to or greater than 2, that is, when the first cycle is repeated, the target film WB is preferably an oxide film. If the target film WB is an oxide film, the modifying gas can replace a portion of the target film WB (a portion close to the top surface W1a of the convex portion) with a boron oxide film WA in step S102 from the second time onward. This allows the target film WB to be selectively embedded deep into the concave portion in step S103 from the second time onward.

[0066] Step S105 includes etching the boron oxide film WA modified with the modifying gas with an etching gas (see FIG. 6). The etching gas is not particularly limited, but is preferably, for example, a rare gas plasma. The rare gas plasma sputters the boron oxide film WA and promotes its volatilization. As a result, etching of the boron oxide film WA progresses. The rare gas includes He, Ne, Ar, Kr, or Xe.

[0067] The etching gas is not limited to plasma of rare gas. ２ , O ２ , COS, N.H. ３ , S.O. ２ , CO ２ , CO, CH ４ , NO ２ , NO or N ２ The etching gas may contain Cl ２ , F ２ , HF, XeF ２ , ClF ３ , BrF ３ , HCl, Br ２ , HBr, I ２ , HI, SOCl ２ , S.O. ２ Cl ２ , or SF ６ The etching gas may also contain CF ４ , C.H. ３ F, CHF ３ , C ４ F ６ , C ４ F ８ , C.H. ３ Cl, or CH ３ The etching gas may contain Br. These etching gases may be turned into plasma. The etching gas may etch not only the boron oxide film WA but also a part of the target film WB.

[0068] Step S106 includes checking whether the second cycle has been performed L times (L is an integer greater than or equal to 1). The second cycle includes supplying a modifying gas (step S102), forming the target film WB (step S103), and supplying an etching gas (step S105). L may be an integer greater than or equal to 2, and the second cycle may be repeatedly performed multiple times. When the target film WB is embedded inside the recess W1b, the occurrence of seams and voids can be suppressed.

[0069] When L in the second cycle is an integer equal to or greater than 2, i.e., when the second cycle is repeated, the target film WB is preferably an oxide film. If the target film WB is an oxide film, the modifying gas can replace a portion of the target film WB (a portion near the top surface W1a of the convex portion) with a boron oxide film WA in the second or subsequent step S102 (see FIG. 7). This allows the target film WB to be selectively embedded deep into the recess W1b in the second or subsequent step S103. Furthermore, the opening of the recess W1b can be widened before the second or subsequent step S103, thereby suppressing the occurrence of seams and voids in the second or subsequent step S103.

[0070] 5, step S107 includes, for example, steps S107a to S107e. Note that step S107 may include at least steps S107a, S107c, and S107e, and does not necessarily include steps S107b and S107d. Steps S107a to S107e will be described below.

[0071] The purpose of performing step S107 is at least one of (1) widening the opening of the recess W1b and (2) widening the opening of the target film WB when the target film WB is an oxide film.

[0072] Step S107a, like step S102, includes supplying a modifying gas to the substrate W. The modifying gas is preferably the same as the modifying gas used in step S102. The modifying gas is preferably BCl ３ , B(CH ３ ) ３ , B ２ H ６ , B.F. ３ , BBr３ , B.I. ３ , C ９ H ２４ BN ３ , C ３ H ９ B, C ６ H １５ B and B ３ N ３ H ６ It is preferable that the modifying gas contains at least one of the following. The modifying gas selectively modifies the top surface W1a of the convex portion and its vicinity relative to the bottom surface W1b2 of the concave portion W1b and its vicinity. The modifying gas contains boron and modifies a portion of the oxide film W1 into a boron oxide film WA. The deeper the depth from the top surface W1a of the convex portion, the more difficult it is for the modifying gas to penetrate, and the more difficult it is for the boron oxide film WA to be formed. Almost no boron oxide film WA is formed on the bottom surface W1b2 of the concave portion W1b and its vicinity.

[0073] Step S107b includes supplying a purge gas to the substrate W. The purge gas purges excess modifying gas that was not used in the modification of the substrate W in step S107a. The purge gas may be, for example, a rare gas such as Ar gas or N ２ A gas is used.

[0074] Step S107c, like step S105, includes supplying an etching gas to the substrate W. The etching gas is preferably the same as the etching gas used in step S105. The etching gas is not particularly limited, but may be, for example, a rare gas plasma. The rare gas plasma sputters the boron oxide film WA to promote volatilization. As a result, etching of the boron oxide film WA progresses. The rare gas includes He, Ne, Ar, Kr, or Xe.

[0075] The etching gas is not limited to plasma of rare gas. ２ , O ２ , COS, N.H. ３ , S.O. ２ , CO ２ , CO, CH ４ , NO ２ , NO or N ２ The etching gas may contain Cl２ , F ２ , HF, XeF ２ , ClF ３ , BrF ３ , HCl, Br ２ , HBr, I ２ , HI, SOCl ２ , S.O. ２ Cl ２ , or SF ６ The etching gas may also contain CF ４ , C.H. ３ F, CHF ３ , C ４ F ６ , C ４ F ８ , C.H. ３ Cl, or CH ３ The etching gas may contain Br. These etching gases may be turned into plasma. The etching gas may etch not only the boron oxide film WA but also a part of the target film WB.

[0076] Step S107d includes supplying a purge gas to the substrate W. The purge gas purges excess etching gas that did not react with the substrate W in step S107c. The purge gas may be, for example, a rare gas such as Ar gas or N ２ A gas is used.

[0077] Step S107e includes checking whether the fifth cycle has been performed J times (J is an integer equal to or greater than 1). The fifth cycle includes steps S107a to S107d. J may be an integer equal to or greater than 2, and the fifth cycle may be repeatedly performed multiple times. This can increase the etching amount of the oxide film W1.

[0078] If the fifth cycle has been performed less than J times (step S107e, NO), the opening of the recess W1b has not been expanded to the desired width, or if the embedded target film WB is an oxide film, the opening of the target film WB has not been expanded to the desired width, so the fifth cycle is performed again. J is preferably 5 or more, more preferably 10 or more. J is preferably 100 or less.

[0079] On the other hand, if the fifth cycle has been performed J times (YES in step S107e), the current process ends. The fact that the fifth cycle has been performed J times may include (1) the opening of the recess W1b reaching a desired width, or (2) if the target film WB is an oxide film, the opening of the target film WB reaching a desired width.

[0080] In step S107, the supply of the modifying gas (step S107a) and the supply of the etching gas (step S107c) are performed without forming the target film WB in between. Etching of the oxide film W1 can proceed as long as the oxide film W1 and the target film WB remain. By performing step S107, the opening of the recess W1b can be widened. Furthermore, when the target film WB is an oxide film, the opening of the target film WB can be widened. This makes it possible to suppress the occurrence of seams and voids when filling the recess W1b with the target film WB in step S109.

[0081] Step S108 includes checking whether the third cycle has been performed M times (M is an integer greater than or equal to 1). The third cycle includes supplying a modifying gas (step S102), forming the target film WB (step S103), and supplying an etching gas (step S105), and then supplying a modifying gas (step S107a) and an etching gas (step S107c) without forming the target film WB in between. M may be an integer greater than or equal to 2, and the third cycle may be repeated multiple times. When the target film WB is embedded inside the recess W1b, the occurrence of seams and voids can be suppressed.

[0082] When M in the third cycle is an integer equal to or greater than 2, i.e., when the third cycle is repeated, the target film WB is preferably an oxide film. If the target film WB is an oxide film, the modifying gas can replace a portion of the target film WB (a portion near the top surface W1a of the convex portion) with a boron oxide film WA in the second or subsequent step S102. This allows the target film WB to be selectively embedded deep into the recess W1b in the second or subsequent step S103. Furthermore, the opening of the recess W1b can be widened before the second or subsequent step S103, thereby suppressing the occurrence of seams and voids in the second or subsequent step S103.

[0083] Step S109 includes filling the recess W1b with a target film WB. The target film WB is formed by a method such as CVD, ALD, or plating. The target film WB is preferably formed not only in the recess W1b but also on the top surface W1a of the protrusion. Although not shown, the substrate processing method may include a step of polishing the target film WB after step S109. Note that step S109 may be performed after step S106, rather than after step S108.

[0084] As described above, the substrate processing method of this modified example includes steps S101 to S103, similar to the substrate processing method of the above embodiment. In step S103, selective deposition of a target film WB is performed. In the selective deposition of the target film WB, a boron oxide film WA is used as an inhibiting film that inhibits deposition of the target film WB. In step S102, a modifying gas containing boron is supplied to the substrate W to modify a portion of the oxide film W1 into a boron oxide film WA. Thus, the boron oxide film WA can be formed by a simple process.

[0085] Furthermore, the substrate processing method of this modified example includes step S105 in addition to steps S101 to S103, as in the substrate processing method of the above embodiment. In step S105, the boron oxide film WA is etched with an etching gas. This allows the unnecessary boron oxide film WA to be removed. Furthermore, when the second cycle is repeated, the opening of the recess W1b can be widened.

[0086] Furthermore, unlike the substrate processing method of the above embodiment, the substrate processing method of this modification includes step S107 in addition to steps S101 to S105. Step S107a includes supplying a modifying gas to the substrate W. Step S107c includes supplying an etching gas to the substrate W. Step S107 can widen the opening of the recess W1b.

[0087] Next, a substrate processing apparatus 100 for performing the above-described film formation method will be described with reference to Fig. 9. As shown in Fig. 9, the substrate processing apparatus 100 has a first processing unit 200A, a second processing unit 200B, a third processing unit 200C, a transport unit 400, and a control unit 500. The first processing unit 200A performs step S102 of Fig. 1. The second processing unit 200B performs step S103 of Fig. 1. The third processing unit 200C performs step S105 of Fig. 1. It is also possible for the first processing unit 200A to perform all of steps S102, S103, and S105 of Fig. 1.

[0088] The substrate processing apparatus 100 may also perform the film formation method shown in FIG. 4 instead of the film formation method shown in FIG. 1 . For example, the first processing apparatus 200A performs steps S102 and S107a in FIG. 4 . Note that steps S102 and S107a may be performed in separate processing apparatuses. The second processing apparatus 200B performs step S103 in FIG. 4 . The third processing apparatus 200C performs steps S105 and S107c in FIG. 4 . Note that steps S105 and S107c may be performed in separate processing apparatuses. The first processing apparatus 200A may also perform all of steps S102, S103, S105, S107a, and S107c in FIG. 4 . Step S109 in FIG. 4 may be performed in an apparatus external to the substrate processing apparatus 100.

[0089] The transport unit 400 transports substrates W to the first processing unit 200A, the second processing unit 200B, and the third processing unit 200C. The transport unit 400 loads the substrates W into the processing vessel 210 (see FIG. 10 ) such as the first processing unit 200A, and loads the substrates W out of the processing vessel 210. The transport unit 400 has a first transport chamber 401 and a first transport mechanism 402. The internal atmosphere of the first transport chamber 401 is the air atmosphere. The first transport mechanism 402 is provided inside the first transport chamber 401. The first transport mechanism 402 includes an arm 403 that holds the substrate W, and travels along rails 404. The rails 404 extend in the arrangement direction of the carriers C.

[0090] The transfer unit 400 also has a second transfer chamber 411 and a second transfer mechanism 412. The internal atmosphere of the second transfer chamber 411 is a vacuum atmosphere. The second transfer mechanism 412 is provided inside the second transfer chamber 411. The second transfer mechanism 412 includes an arm 413 that holds the substrate W, and the arm 413 is arranged to be movable vertically and horizontally and rotatable about a vertical axis. The second transfer chamber 411 is connected to a first processing unit 200A, a second processing unit 200B, and a third processing unit 200C via different gate valves G.

[0091] Furthermore, the transfer unit 400 has a load lock chamber 421 between the first transfer chamber 401 and the second transfer chamber 411. The internal atmosphere of the load lock chamber 421 can be switched between a vacuum atmosphere and an atmospheric atmosphere by a pressure adjustment mechanism (not shown). This allows the interior of the second transfer chamber 411 to be constantly maintained in a vacuum atmosphere. Also, it is possible to prevent gas from flowing from the first transfer chamber 401 into the second transfer chamber 411. Gate valves G are provided between the first transfer chamber 401 and the load lock chamber 421, and between the second transfer chamber 411 and the load lock chamber 421.

[0092] The control unit 500 is, for example, a computer, and includes an arithmetic unit 501 such as a CPU (Central Processing Unit), and a storage unit 502 such as a memory. The storage unit 502 stores programs that control various processes executed in the substrate processing apparatus 100. The control unit 500 controls the operation of the substrate processing apparatus 100 by causing the arithmetic unit 501 to execute the programs stored in the storage unit 502. The control unit 500 controls the first processing unit 200A, the second processing unit 200B, the third processing unit 200C, and the transport unit 400 to perform the above-described film formation method.

[0093] The program, i.e., a computer program product, may be supplied in a form recorded on a removable storage medium such as a memory card, an optical disk, or a hard disk drive (HDD). The control unit 500 reads the program from the storage medium and stores it in the storage unit 502. The storage unit 502 includes a storage medium such as an HDD, a solid state drive (SDD), or an electronically erasable programmable read-only memory (EEPROM). The program may be written in advance to the storage medium of the storage unit 502. The control unit 500 may also obtain the program distributed by a remote server device or the like via a network or other communication.

[0094] The control unit 500 includes electronic circuits such as a CPU, a graphics processing unit (GPU), a field programmable gate array (FPGA), or an application specific integrated circuit (ASIC). The control unit 500 executes various control operations described in this specification by executing instruction codes stored in a storage medium such as a memory, or by being a circuit designed for a specific application.

[0095] Next, the operation of the substrate processing apparatus 100 will be described. First, the first transport mechanism 402 removes the substrate W from the carrier C, transports the removed substrate W to the load lock chamber 421, and exits from the load lock chamber 421. Next, the internal atmosphere of the load lock chamber 421 is switched from the atmospheric atmosphere to a vacuum atmosphere. Thereafter, the second transport mechanism 412 removes the substrate W from the load lock chamber 421 and transports the removed substrate W to the first processing unit 200A.

[0096] Next, the first processing unit 200A performs step S102 in Fig. 1. Thereafter, the second transport mechanism 412 removes the substrate W from the first processing unit 200A and transports the removed substrate W to the second processing unit 200B. During this time, the substrate W can be protected by a vacuum atmosphere, and contamination of the substrate W with organic compounds in the air can be suppressed.

[0097] Next, second processing apparatus 200B performs step S103 in Fig. 1 . Next, control unit 500 performs step S104 in Fig. 1 . If the first cycle has not been performed K times (step S104, NO), second transport mechanism 412 removes the substrate W from second processing apparatus 200B and transports the removed substrate W to first processing apparatus 200A. Thereafter, the first cycle is performed again.

[0098] On the other hand, when the first cycle has been performed K times (step S104, YES), the second transport mechanism 412 removes the substrate W from the second processing unit 200B and transports the removed substrate W to the third processing unit 200C. During this time, the substrate W can be protected by a vacuum atmosphere, and contamination of the substrate W with organic compounds in the air can be suppressed.

[0099] Next, the third processing unit 200C performs step S105 in Fig. 1. Next, the control unit 500 performs step S106 in Fig. 1. If the number of times the second cycle has been performed has not reached L (step S106, NO), the second transport mechanism 412 removes the substrate W from the third processing unit 200C and transports the removed substrate W to the first processing unit 200A. Thereafter, the second cycle is performed again.

[0100] On the other hand, when the number of times the second cycle has been performed reaches L (step S106, YES), the second transport mechanism 412 removes the substrate W from the third processing unit 200C, transports the removed substrate W to the load lock chamber 421, and exits from the load lock chamber 421. The internal atmosphere of the load lock chamber 421 is then switched from a vacuum atmosphere to an atmospheric atmosphere. Thereafter, the first transport mechanism 402 removes the substrate W from the load lock chamber 421 and stores the removed substrate W in the carrier C. Then, the processing of the substrate W is completed.

[0101] Next, the first processing unit 200A will be described with reference to Fig. 10. The configurations of the second processing unit 200B and the third processing unit 200C are similar to the configuration of the first processing unit 200A, and therefore will not be shown or described here.

[0102] The first processing unit 200A includes a substantially cylindrical, airtight processing vessel 210. An exhaust chamber 211 is provided in the center of the bottom wall of the processing vessel 210. The exhaust chamber 211 has, for example, a substantially cylindrical shape that protrudes downward. An exhaust pipe 212 is connected to the exhaust chamber 211, for example, at a side surface of the exhaust chamber 211.

[0103] An exhaust source 272 is connected to the exhaust pipe 212 via a pressure controller 271. The pressure controller 271 includes a pressure adjustment valve such as a butterfly valve. The exhaust pipe 212 is configured so that the pressure inside the processing vessel 210 can be reduced by the exhaust source 272. The pressure controller 271 and the exhaust source 272 constitute a gas exhaust mechanism 270 that exhausts gas inside the processing vessel 210.

[0104] A transfer port 215 is provided on the side surface of the processing vessel 210. The transfer port 215 is opened and closed by a gate valve G. The substrate W is transferred in and out between the processing vessel 210 and the second transfer chamber 411 (see FIG. 9 ) via the transfer port 215.

[0105] A stage 220, which is a holder for holding a substrate W, is provided within the processing vessel 210. The stage 220 holds the substrate W horizontally with the surface of the substrate W on which the target film WB is to be formed facing upward. The stage 220 is formed in a substantially circular shape in a plan view and is supported by a support member 221. A substantially circular recess 222 for placing a substrate W having a diameter of, for example, 300 mm is formed in the surface of the stage 220. The recess 222 has an inner diameter slightly larger than the diameter of the substrate W. The depth of the recess 222 is configured to be substantially the same as the thickness of the substrate W, for example. The stage 220 is made of a ceramic material such as aluminum nitride (AlN). Alternatively, the stage 220 may be made of a metal material such as nickel (Ni). Note that instead of the recess 222, a guide ring for guiding the substrate W may be provided around the periphery of the surface of the stage 220.

[0106] A grounded lower electrode 223, for example, is embedded in the stage 220. A heating mechanism 224 is embedded below the lower electrode 223. The heating mechanism 224 receives power from a power supply unit (not shown) based on a control signal from the control unit 500 (see FIG. 9), thereby heating the substrate W placed on the stage 220 to a set temperature. If the entire stage 220 is made of metal, the entire stage 220 functions as the lower electrode, so the lower electrode 223 does not need to be embedded in the stage 220. The stage 220 is provided with a plurality of (for example, three) lifting pins 231 for holding and lifting up and down the substrate W placed on the stage 220. The lifting pins 231 are made of a material such as alumina (Al ２ O ３ The lift pins 231 may be made of ceramics such as quartz or the like. The lower ends of the lift pins 231 are attached to a support plate 232. The support plate 232 is connected to a lift mechanism 234 provided outside the processing vessel 210 via a lift shaft 233.

[0107] The lifting mechanism 234 is installed, for example, below the exhaust chamber 211. The bellows 235 is provided between the lifting mechanism 234 and an opening 219 for the lifting shaft 233 formed in the lower surface of the exhaust chamber 211. The support plate 232 may be shaped so that it can be raised and lowered without interfering with the support member 221 of the stage 220. The lifting pins 231 are configured to be able to be raised and lowered by the lifting mechanism 234 between above and below the surface of the stage 220.

[0108] A gas supply unit 240 is provided on the ceiling wall 217 of the processing vessel 210 via an insulating member 218. The gas supply unit 240 serves as an upper electrode and faces the lower electrode 223. A high-frequency power supply 252 is connected to the gas supply unit 240 via a matching unit 251. By supplying high-frequency power of 100 kHz to 2.45 GHz, preferably 450 kHz to 100 MHz, from the high-frequency power supply 252 to the upper electrode (gas supply unit 240), a high-frequency electric field is generated between the upper electrode (gas supply unit 240) and the lower electrode 223, thereby generating capacitively coupled plasma. A plasma generation unit 250 that generates plasma includes the matching unit 251 and the high-frequency power supply 252. Note that the plasma generation unit 250 is not limited to capacitively coupled plasma, and may generate other types of plasma, such as inductively coupled plasma or remote plasma. Note that in steps that do not generate plasma, the gas supply unit 240 does not need to serve as an upper electrode, and the lower electrode 223 is also not required.

[0109] The gas supply unit 240 includes a hollow gas supply chamber 241. A number of holes 242 are arranged, for example, evenly, on the bottom surface of the gas supply chamber 241 to distribute and supply the processing gas into the processing vessel 210. A heating mechanism 243 is embedded in the gas supply unit 240, for example, above the gas supply chamber 241. The heating mechanism 243 is heated to a set temperature by receiving power from a power supply unit (not shown) based on a control signal from the control unit 500.

[0110] A gas supply mechanism 260 is connected to the gas supply chamber 241 via a gas supply path 261. The gas supply mechanism 260 supplies gases to be used in desired steps in FIG. 1 or 4 to the gas supply chamber 241 via the gas supply path 261. Although not shown, the gas supply mechanism 260 includes individual pipes for each type of gas, on-off valves provided midway through the individual pipes, and flow rate controllers provided midway through the individual pipes. When the on-off valves open the individual pipes, gas is supplied from the supply source to the gas supply path 261. The supply amount is controlled by the flow rate controller. On the other hand, when the on-off valves close the individual pipes, the supply of gas from the supply source to the gas supply path 261 is stopped.

[0111] Although the embodiments of the film forming method and film forming apparatus according to the present disclosure have been described above, the present disclosure is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure.

[0112] This application claims priority based on Japanese Patent Application No. 2024-152913 filed with the Japan Patent Office on September 5, 2024, the entire contents of which are incorporated herein by reference.

[0113] W substrate W1 oxide film W2 non-oxide film WA boron oxide film WB target film

Claims

1. A film forming method comprising: preparing a substrate having an oxide film that contains substantially no boron and a non-oxide film that contains substantially no oxygen in different surface regions; supplying a modifying gas that contains boron to the substrate to modify at least the surface of the oxide film into a boron oxide film; and selectively forming a target film on the surface of the non-oxide film relative to the surface of the boron oxide film, wherein the target film contains a desired element X, and forming the target film comprises supplying to the substrate a source gas that contains a compound of the element X and a halogen, and a reactive gas that reacts with an adsorbate of the source gas.

2. The film forming method according to claim 1, wherein the oxide film contains a compound of a metal and oxygen or a compound of a semiconductor element and oxygen.

3. The film forming method according to claim 1, wherein the non-oxide film has an oxygen content of 0 at % to 10 at %.

4. The reforming gas is BCl ３ , B(CH ３ ) ３ , B ２ H ６ , B.F. ３ , BBr ３ , B.I. ３ , C ９ H ２４ BN ３ , C ３ H ９ B, C ６ H １５ B and B ３ N ３ H ６ The film forming method according to claim 1 , comprising at least one of the following:

5. The film formation method according to claim 1, wherein the target film is substantially free of oxygen, and the film formation method comprises repeating a first cycle including supplying the modifying gas and forming the target film multiple times.

6. The film forming method according to claim 1, further comprising etching the boron oxide film with an etching gas after forming the target film.

7. The film formation method according to claim 6, wherein the target film is substantially free of oxygen, and the film formation method repeats a second cycle including supplying the modifying gas, forming the target film, and supplying the etching gas multiple times.

8. A film forming method comprising: preparing a substrate having an oxide film substantially free of boron on its surface, the oxide film having top surfaces of convex portions and concave portions recessed from the top surfaces of the convex portions on the surface of the oxide film; supplying a modifying gas containing boron to the substrate to selectively modify the top surfaces of the convex portions and their vicinity relative to the bottom surfaces of the concave portions and their vicinity into a boron oxide film; and forming a target film selectively on the bottom surfaces of the concave portions and their vicinity relative to the top surfaces of the convex portions modified to the boron oxide film and their vicinity, the target film containing a desired element X, and forming the target film includes supplying to the substrate a source gas containing a compound of the element X and a halogen, and a reaction gas that reacts with an adsorbate of the source gas.

9. The film forming method according to claim 8, wherein the oxide film contains a compound of a metal and oxygen or a compound of a semiconductor element and oxygen.

10. The reforming gas is BCl ３ , B(CH ３ ) ３ , B ２ H ６ , B.F. ３ , C ９ H ２４ BN ３ , C ３ H ９ B, C ６ H １５ B and B ３ N ３ H ６ The film forming method according to claim 8 , comprising at least one of the following:

11. The film forming method according to claim 8, wherein the first cycle including the supply of the modifying gas and the formation of the target film is repeated multiple times.

12. The film forming method according to claim 8, further comprising etching the boron oxide film with an etching gas after forming the target film.

13. The film formation method according to claim 12, wherein the second cycle including the supply of the modifying gas, the formation of the target film, and the supply of the etching gas is repeated multiple times.

14. The film forming method according to claim 12, wherein after the supply of the modifying gas, the formation of the target film, and the supply of the etching gas, the supply of the modifying gas and the supply of the etching gas are carried out one or more times without forming the target film in between.

15. The film forming method according to claim 14, wherein a third cycle including supplying the modifying gas, forming the target film, and supplying the etching gas, and subsequently supplying the modifying gas and the etching gas one or more times without forming the target film therebetween, is repeated multiple times.

16. A film formation apparatus comprising: a processing unit including a processing vessel that accommodates the substrate, a holding unit that holds the substrate inside the processing vessel, and a gas supply unit that supplies gas to the substrate held in the holding unit; a transport unit that loads the substrate into the processing vessel and loads the substrate out of the processing vessel; and a control unit that controls the processing unit and the transport unit, wherein the control unit controls the processing unit and the transport unit to perform the film formation method described in any one of claims 1 to 15.

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