Substrate treatment method and substrate treatment apparatus

Abstract

To provide a substrate treatment method and a substrate treatment apparatus, which are for forming a boron nitride thin film on a substrate.SOLUTION: This substrate treatment method includes the steps of: preparing a substrate having an underlayer; exposing the substrate to a first boron-containing gas to form a deposited layer of a boron-containing substance on the substrate; exposing the substrate having the deposited layer of the boron-containing substance formed thereon to a plasma of a first treatment gas containing a first nitrogen-containing gas so as to nitride the deposited layer of the boron-containing substance and form a nucleus of the boron nitride-containing substance; and exposing the substrate having the nucleus of the boron nitride-containing substance formed thereon to a plasma of a second treatment gas containing a second boron-containing gas and a second nitrogen-containing gas, which is different from the first nitrogen-containing gas, so as to form a boron nitride film on the substrate.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus. [Background technology]

[0002] Patent Document 1 discloses a film formation method in which plasma is generated in a film formation chamber, nitrogen gas is mainly excited in the film formation chamber, and then mixed with a boron-based gas to react with it to form a boron nitride film on a substrate, and an amorphous phase generation suppression gas is supplied in the early stages of film formation to suppress the generation of an amorphous phase at the interface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-289618 A Summary of the Invention [Problem to be solved by the invention]

[0004] In one aspect, the present disclosure provides a substrate processing method and a substrate processing apparatus for forming a thin boron nitride film on a substrate. [Means for solving the problem]

[0005] In order to solve the above problem, according to one aspect, there is provided a substrate processing method comprising the steps of: preparing a substrate having an underlayer; exposing the substrate to a first boron-containing gas to form a deposition layer of a boron-containing material on the substrate; exposing the substrate on which the deposition layer of the boron-containing material has been formed to a plasma of a first process gas containing a first nitrogen-containing gas to nitrify the deposition layer of the boron-containing material to form nuclei of boron nitride-containing material; and exposing the substrate on which the nuclei of the boron nitride-containing material have been formed to a plasma of a second process gas containing a second boron-containing gas and a second nitrogen-containing gas different from the first nitrogen-containing gas to form a boron nitride film on the substrate. Effect of the Invention

[0006] According to one aspect, the present disclosure can provide a substrate processing method and a substrate processing apparatus for forming a thin boron nitride film on a substrate. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view showing an example of a substrate processing apparatus according to an embodiment of the present invention; [Diagram 2] 1 is a flowchart showing an example of a method for forming an h-BN film according to an embodiment of the present invention. [Diagram 3] 5A to 5C are examples of schematic cross-sectional views of the substrate W in each step according to the present embodiment. [Figure 4] 1 is an example of a graph showing the relationship between a nitrogen-containing gas and a nitriding reaction. [Diagram 5] 1 is a flowchart showing an example of a method for forming an h-BN film according to a reference example. [Figure 6] 5A to 5C are examples of schematic cross-sectional views of a substrate W in each step according to a reference example. [Figure 7] 1 is an example of a graph showing the relationship between a nitrogen-containing gas and a nitriding reaction. [Figure 8] FIG. 2 is a cross-sectional view showing a boron nitride film formed by the h-BN film forming method according to the embodiment. [Figure 9] FIG. 2 is a cross-sectional view showing a boron nitride film formed by a method for forming an h-BN film according to a reference example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and duplicated descriptions may be omitted.

[0009] <Substrate processing equipment> An example of a substrate processing apparatus 1 according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing an example of the substrate processing apparatus 1 according to this embodiment. The substrate processing apparatus 1 is a film formation apparatus that forms a hexagonal boron nitride (hereinafter also referred to as "h-BN") film on a substrate W such as a wafer by a PE-CVD (Plasma-Enhanced Chemical Vapor Deposition) method in a processing container 2 under reduced pressure.

[0010] The substrate processing apparatus 1 includes a substantially cylindrical airtight processing vessel 2. An exhaust chamber 21 is provided in the center of the bottom wall of the processing vessel 2.

[0011] The exhaust chamber 21 has, for example, a substantially cylindrical shape that protrudes downward. An exhaust flow path 22 is connected to the exhaust chamber 21, for example, at a side surface of the exhaust chamber 21. An exhaust unit 24 is connected to the exhaust flow path 22 via a pressure adjustment unit 23. The pressure adjustment unit 23 includes, for example, a pressure adjustment valve such as a butterfly valve. The exhaust flow path 22 is configured so that the inside of the processing vessel 2 can be decompressed by the exhaust unit 24. A transfer port 25 is provided at a side surface of the processing vessel 2. The transfer port 25 is configured so as to be freely opened and closed by a gate valve 26. The substrate W is loaded and unloaded between the inside of the processing vessel 2 and a transfer chamber (not shown) via the transfer port 25.

[0012] A mounting table 3 for holding the substrate W substantially horizontally is provided in the processing vessel 2. The mounting table 3 is formed in a substantially circular shape in a plan view, and is supported by a support member 31. A substantially circular recess 32 for mounting the substrate W having a diameter of, for example, 300 mm is formed on the surface of the mounting table 3. The recess 32 has an inner diameter that is slightly larger (for example, about 1 mm to 4 mm) than the diameter of the substrate W. The depth of the recess 32 is configured to be substantially the same as the thickness of the substrate W. The mounting table 3 is formed of a ceramic material such as aluminum nitride (AlN). The mounting table 3 may be formed of a metal material such as nickel (Ni). Instead of the recess 32, a guide ring for guiding the substrate W may be provided on the periphery of the surface of the mounting table 3.

[0013] A lower electrode 33 is embedded in the mounting table 3. A temperature adjustment mechanism 34 is embedded below the lower electrode 33. The temperature adjustment mechanism 34 adjusts the temperature of the substrate W placed on the mounting table 3 to a set temperature based on a control signal from the control unit 9. When the mounting table 3 is entirely made of metal, the entire mounting table 3 functions as the lower electrode, so that the lower electrode 33 does not need to be embedded in the mounting table 3.

[0014] An RF power supply 35 is connected to the lower electrode 33 via a matching unit 351. The RF power supply 35 applies low frequency power (LF) having a frequency lower than that of an RF power supply 51 described later, to the lower electrode 33. The high frequency power generated by the RF power supply 35 is used as a bias high frequency power for attracting ions into the substrate W. The frequency of the RF power supply 35 is, for example, 13.56 MHz.

[0015] The mounting table 3 is provided with a plurality of (e.g., three) lift pins 41 for holding and lifting the substrate W mounted on the mounting table 3. The material of the lift pins 41 may be, for example, ceramics such as alumina (Al2O3) or quartz. The lower ends of the lift pins 41 are attached to a support plate 42. The support plate 42 is connected via a lift shaft 43 to a lift mechanism 44 provided outside the processing chamber 2.

[0016] The lifting mechanism 44 is installed, for example, at the bottom of the exhaust chamber 21. The bellows 45 is provided between the lifting mechanism 44 and an opening 211 for the lifting shaft 43 formed in the bottom surface of the exhaust chamber 21. The support plate 42 may be shaped so that it can be raised and lowered without interfering with the support member 31 of the mounting table 3. The lifting pins 41 are configured to be freely raised and lowered between the upper side and the lower side of the surface of the mounting table 3 by the lifting mechanism 44. In other words, the lifting pins 41 are configured to be able to protrude from the top surface of the mounting table 3.

[0017] Furthermore, the lower end of the support member 31 penetrates the opening 212 of the exhaust chamber 21, and is supported by a lifting mechanism 46 via a lifting plate 47 disposed below the processing vessel 2. A bellows 48 is provided between the bottom of the exhaust chamber 21 and the lifting plate 47, so that the airtightness inside the processing vessel 2 is maintained even when the lifting plate 47 moves up and down.

[0018] The lifting mechanism 46 lifts and lowers the lifting plate 47, thereby lifting and lowering the mounting table 3. In this way, the gap between the mounting table 3 and the gas supply unit 5 can be adjusted.

[0019] A gas supply unit 5 is provided on the ceiling wall 27 of the processing vessel 2 via an insulating member 28. The gas supply unit 5 constitutes an upper electrode and faces the lower electrode 33. An RF power supply 51 is connected to the gas supply unit 5 via a matching unit 511. The RF power supply 51 applies high frequency power having a higher frequency than the frequency of the RF power supply 35 to the upper electrode (gas supply unit 5). The high frequency power generated by the RF power supply 51 is used as high frequency power for generating plasma required for film formation on the substrate W. The frequency of the RF power supply 51 is, for example, a VHF (Very High Frequency) band of 100 MHz to 900 MHz. An RF electric field is generated between the upper electrode (gas supply unit 5) and the lower electrode 33 by supplying RF power from the RF power supply 51 to the upper electrode (gas supply unit 5). The RF power supply 51, the upper electrode (gas supply unit 5), and the lower electrode 33 constitute a plasma generation unit that generates plasma. The gas supply unit 5 includes a hollow gas diffusion chamber 52. A number of holes 53 for dispersing and supplying the processing gas into the processing vessel 2 are arranged, for example, uniformly on the bottom surface of the gas diffusion chamber 52. A heating mechanism 54 is embedded in the gas supply unit 5, for example, above the gas diffusion chamber 52. The heating mechanism 54 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 9.

[0020] The gas diffusion chamber 52 is provided with a gas supply path 6. The gas supply path 6 communicates with the gas diffusion chamber 52. A gas source 61 is connected to the upstream side of the gas supply path 6 via a gas line 62. The gas source 61 includes, for example, a supply source of various processing gases, a mass flow controller, and valves (none of which are shown). The various processing gases include a boron-containing gas and a nitrogen-containing gas used in the formation of the h-BN film. Further, the various processing gases include an inert gas (e.g., Ar gas) for generating plasma. The various processing gases are introduced from the gas source 61 into the gas diffusion chamber 52 via the gas line 62.

[0021] The substrate processing apparatus 1 includes a control unit 9. The control unit 9 is, for example, a computer and includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an auxiliary storage device, and the like. The CPU operates based on a program stored in the ROM or the auxiliary storage device and controls the operation of the substrate processing apparatus 1. The control unit 9 may be provided inside the substrate processing apparatus 1 or outside the substrate processing apparatus 1. When the control unit 9 is provided outside the substrate processing apparatus 1, the control unit 9 can control the substrate processing apparatus 1 by means of communication means such as wired or wireless.

[0022] <Method for forming h-BN film> Next, an example of the method for forming the h-BN film (substrate processing method) according to the present embodiment will be described with reference to FIGS. 2 and 3. FIG. 2 is a flowchart showing an example of the method for forming the h-BN film according to the present embodiment. FIG. 3 is an example of a cross-sectional schematic view of the substrate W in each step according to the present embodiment.

[0023] In step S101, a substrate W is prepared. The substrate W has an underlayer 700 (see FIG. 3(a) described later). The underlayer 700 is, for example, any one of SiO2, HfO2, HfSiO4, HfSiON, ZrO2, amorphous silicon, sapphire, etc. Here, the control unit 9 controls a transfer device (not shown) to place the substrate W on the mounting table 3 of the substrate processing apparatus 1. When the transfer device retreats from the transfer port 25, the control unit 9 closes the gate valve 26.

[0024] In step S102, a first boron-containing gas (e.g., B2H6) is supplied to the processing vessel 2. Here, the control unit 9 controls a valve of the gas source 61 and the like to supply the first boron-containing gas to the processing vessel 2. As a result, the substrate W in the processing vessel 2 is exposed to the first boron-containing gas, and a deposition layer (also referred to as a boron-containing film) 710 of a boron-containing material is formed on the surface of the underlayer 700 of the substrate W. Then, when a predetermined processing time has elapsed, the control unit 9 controls a valve of the gas source 61 and the like to stop the supply of the first boron-containing gas to the processing vessel 2.

[0025] Here, the first boron-containing gas is, for example, at least one gas selected from the group consisting of B2H6 (diborane), BCl3 (boron trichloride), B3N3H6 (borazine), B(CH3)3 (trimethylborane), etc. In the following description, the first boron-containing gas is exemplified by B2H6.

[0026] An example of the recipe in step S102 is shown below. Pressure inside processing vessel: 10mTorr~200mTorr Mounting table temperature: 600℃~900℃

[0027] 3(a) is an example of a schematic cross-sectional view of the substrate W after the process of step S102. By supplying a first boron-containing gas to the substrate W, a deposition layer 710 of a boron-containing material is formed by CVD film formation. Alternatively, by supplying the first boron-containing gas to the substrate W, the first boron-containing gas is adsorbed on the surface of the base layer 700 of the substrate W to form a deposition layer 710 of a boron-containing material. Here, the deposition layer 710 of the boron-containing material may be a discontinuous film formed on at least a part of the deposition surface of the substrate W (base layer 700) (the upper surface of the base layer 700 in the example of FIG. 3), or may be a continuous film.

[0028] In step S103, plasma of Ar gas is ignited in the processing vessel 2. Here, the control unit 9 controls the valve of the gas source 61 and the like to supply an inert gas (also referred to as a plasma generating gas) for generating plasma to the processing vessel 2. The inert gas is, for example, at least one gas of Ar, He, and the like. In the following description, the inert gas is an example of Ar gas. In addition, the control unit 9 controls the RF power supply 51 to supply high frequency power for generating plasma to the upper electrode. As a result, plasma of Ar gas is ignited between the upper electrode (gas supply unit 5) and the lower electrode 33.

[0029] 3(b) is an example of a schematic cross-sectional view of the substrate W in step S103. An Ar gas plasma P1 is generated in the processing chamber 2. The substrate W is exposed to the Ar gas plasma P1.

[0030] In step S104, a first nitrogen-containing gas (e.g., NH3) is supplied to the processing vessel 2. Here, from a state in which the plasma P1 of Ar gas is formed, the control unit 9 controls the valve of the gas source 61 and the like to supply the first nitrogen-containing gas to the processing vessel 2. As a result, the substrate W in the processing vessel 2 is exposed to the plasma of the first processing gas containing the first nitrogen-containing gas and Ar gas. As a result, the deposition layer 710 of the boron-containing material is nitrided to form nuclei 721 of the boron nitride-containing material. Then, when a predetermined processing time has elapsed, the control unit 9 controls the valve of the gas source 61 and the like to stop the supply of the first nitrogen-containing gas to the processing vessel 2.

[0031] Here, the first nitrogen-containing gas is, for example, at least one of NH3 (ammonia), a mixed gas of N2 and H2, monomethylhydrazine, etc. In the following description, the first nitrogen-containing gas is NH3 as an example.

[0032] An example of the recipe in step S104 is shown below. Pressure inside processing vessel: 10mTorr~200mTorr Mounting table temperature: 600℃~900℃

[0033] The pressure in step S104 is the same as or higher than the pressure in step S105 described below. By using the same or higher pressure, the nitriding rate is reduced, unnecessary growth is suppressed, and a discontinuous film is easily obtained.

[0034] 3(c) is an example of a schematic cross-sectional view of the substrate W in the process of step S104. A plasma P2 of a first process gas containing a first nitrogen-containing gas (NH3) and Ar gas is generated in the process vessel 2. The plasma P2 of the first process gas nitrides the deposition layer 710 of the boron-containing material (see FIG. 3(b)), and a nucleus 721 of the boron nitride-containing material (also referred to as a first boron nitride film) is formed. Here, the nucleus 721 of the boron nitride-containing material is a discontinuous film formed on at least a part of the deposition surface of the substrate W (underlayer 700) (in the example of FIG. 3, the upper surface of the underlayer 700).

[0035] In step S105, a second boron-containing gas (e.g., B2H6) and a second nitrogen-containing gas (e.g., N2) are supplied to the processing vessel 2. Here, from a state in which the plasma P1 of Ar gas is formed, the control unit 9 controls the valve of the gas source 61 and the like to supply the second boron-containing gas and the second nitrogen-containing gas to the processing vessel 2. As a result, the substrate W in the processing vessel 2 is exposed to the plasma of the second processing gas containing the second boron-containing gas, the second nitrogen-containing gas, and Ar gas. As a result, a boron nitride film (also referred to as a second boron nitride film) 722 is formed from the nucleus 721 of the boron nitride-containing material as a starting point. Then, when a predetermined processing time has elapsed, the control unit 9 controls the valve of the gas source 61 and the like to stop the supply of the second boron-containing gas and the second nitrogen-containing gas to the processing vessel 2. In addition, the control unit 9 controls the RF power source 51 to stop the supply of high-frequency power to the upper electrode. In addition, the control unit 9 controls the valve of the gas source 61 and the like to stop the supply of Ar gas to the processing chamber 2.

[0036] Here, the second boron-containing gas is, for example, at least one of B2H6, BCl3, B3N3H6, B(CH3)3, etc. The second boron-containing gas may be the same gas as the first boron-containing gas, or may be a different gas. In the following description, the second boron-containing gas is described as B2H6.

[0037] The second nitrogen-containing gas is a gas different from the first nitrogen-containing gas. The second nitrogen-containing gas is a nitrogen-containing gas that has a lower reactivity for nitriding the boron-containing material (the first boron-containing gas, the second boron-containing gas, and the deposition layer 710 of the boron-containing material) compared to the first nitrogen-containing gas. As shown in FIG. 7 described later, when a substrate W on which a nucleus 721 of a boron-nitride-containing material is not formed is exposed to a plasma of a second processing gas containing a second boron-containing gas and a second nitrogen-containing gas, the formation of a boron nitride film is suppressed. Specifically, since there is no reaction terminal on the surface of the nucleus 721 of the boron-nitride-containing material, the formation of a boron nitride film by nitridation of boron does not occur, and the boron nitride film does not grow (form) in the vertical direction. Furthermore, since the nucleus 721 of the boron-nitride-containing material has a reaction terminal only in the horizontal direction, the boron nitride film grows (forms) in the horizontal direction. The second nitrogen-containing gas is, for example, at least one of N2, a mixed gas of N2 and H2, etc. When the second nitrogen-containing gas is a mixed gas of N2 and H2, the ratio of nitrogen to hydrogen is different from that of the first nitrogen-containing gas, for example, by making the ratio closer to that of N2 alone or by extremely lowering the partial pressure of N2. In the following description, the second nitrogen-containing gas is described as being N2.

[0038] An example of the recipe in step S105 is shown below. Pressure inside processing vessel: 10mTorr~200mTorr Mounting table temperature: 600℃~900℃

[0039] 3(d) is an example of a schematic cross-sectional view of the substrate W in the process of step S105. A plasma P3 of a second process gas containing a second boron-containing gas (B2H6), a second nitrogen-containing gas (N2), and Ar gas is generated in the process vessel 2. The plasma P3 of the second process gas causes a boron nitride film 722 to grow in the surface direction of the substrate W from nuclei 721 (see FIG. 3(c)) of a boron nitride-containing material as starting points. Meanwhile, the growth of the boron nitride film 722 in the stacking direction of the substrate W is suppressed compared to a reference example described later.

[0040] 3(e) is an example of a schematic cross-sectional view of the substrate W after the process of step S105. The boron nitride film 722 grows in the surface direction of the substrate W, thereby forming the boron nitride film 722 on the underlayer 700 of the substrate W. Moreover, the growth of the boron nitride film 722 in the stacking direction is suppressed, and the thin boron nitride film 722 is formed on the substrate W.

[0041] The method for forming an h-BN film according to this embodiment is carried out in a substrate processing apparatus 1 shown in Fig. 1. In other words, the step of forming the deposition layer 710 of a boron-containing material (S102), the step of forming the nucleus 721 of a boron nitride-containing material (S104), and the step of forming the boron nitride film 722 (S105) have been described as being carried out in one processing vessel 2, but this is not limiting. The step of forming the deposition layer 710 of a boron-containing material (S102), the step of forming the nucleus 721 of a boron nitride-containing material (S104), and the step of forming the boron nitride film 722 (S105) may be carried out in different processing vessels. For example, the substrate processing system may be a multi-chamber substrate processing system including a first substrate processing apparatus that performs a step (S102) of forming a deposition layer 710 of a boron-containing material, a second substrate processing apparatus that performs a step (S104) of forming nuclei 721 of a boron nitride-containing material, a third substrate processing apparatus that performs a step (S105) of forming a boron nitride film 722, a vacuum transfer apparatus connected to the first to third substrate processing apparatuses, and a substrate transfer apparatus provided within the vacuum transfer apparatus.

[0042] Furthermore, for example, the substrate processing system may be a multi-chamber substrate processing system including a first substrate processing apparatus that performs a step (S102) of forming a deposition layer 710 of a boron-containing material and a step (S104) of forming nuclei 721 of a boron nitride-containing material, a second substrate processing apparatus that performs a step (S105) of forming a boron nitride film 722, a vacuum transfer device connected to the first and second substrate processing apparatuses, and a substrate transfer device provided within the vacuum transfer device.

[0043] Furthermore, for example, the substrate processing system may be a multi-chamber substrate processing system including a first substrate processing apparatus that performs a step (S102) of forming a deposition layer 710 of a boron-containing material, a second substrate processing apparatus that performs a step (S104) of forming nuclei 721 of a boron nitride-containing material and a step (S105) of forming a boron nitride film 722, a vacuum transfer device connected to the first and second substrate processing apparatuses, and a substrate transfer device provided within the vacuum transfer device.

[0044] 2, the step (S102) of forming the deposition layer 710 of the boron-containing material, the step (S104) of forming the core 721 of the boron nitride-containing material, and the step (S105) of forming the boron nitride film 722 are described as being performed once each, but the present invention is not limited to this. The process from step S102 to step S105 may be regarded as one cycle, and this cycle may be repeated multiple times. This makes it possible to control the film thickness of the boron nitride film formed on the substrate W by the number of repetitions of the cycle. Also, as described later, the method of forming the h-BN film according to this embodiment makes it possible to reduce the film thickness of the boron nitride film per cycle. This improves the controllability of the film thickness of the boron nitride film.

[0045] Here, the process of nitriding the boron-containing deposition layer 710 to form the boron nitride-containing nuclei 721 in steps S101 to S105 will be further described with reference to Fig. 4. Fig. 4 is an example of a graph showing the relationship between the nitrogen-containing gas and the nitridation reaction. Here, each film formed on the substrate W was analyzed by Fourier transform infrared spectroscopy (FT-IR). The horizontal axis indicates the wavelength (Wavenumber). Also, the vertical axis indicates the absorbance. Also, in Fig. 4, the position of the wavelength corresponding to h-BN and the position of the wavelength corresponding to B-OH are indicated by thin solid lines.

[0046] "Base (B2H6)" indicated by a solid line indicates that a deposition layer 710 of a boron-containing material was formed on a substrate W having an underlayer 700 made of SiO2 using B2H6 as a first boron-containing gas (see step S102 in FIG. 2).

[0047] In the "N2CVD" indicated by the dashed line, a substrate W on which a boron-containing deposition layer 710 was formed using B2H6 was subjected to a nitriding process using plasma of a process gas containing N2 and Ar.

[0048] The dotted line "N2+H2" indicates that the substrate W on which the boron-containing deposition layer 710 was formed using B2H6 was subjected to a nitriding process using plasma of a process gas containing N2, H2, and Ar (see steps S103 and S104 in FIG. 2). That is, this corresponds to the case where a mixed gas of N2 and H2 is used as the first nitrogen-containing gas in the method for forming an h-BN film according to this embodiment.

[0049] The "NH3CVD" indicated by the dashed line indicates that the substrate W on which the boron-containing deposition layer 710 was formed using B2H6 was nitrided using plasma of a process gas containing NH3 and Ar (see steps S103 and S104 in FIG. 2). That is, this corresponds to the case where NH3 gas was used as the first nitrogen-containing gas in the method for forming an h-BN film according to this embodiment.

[0050] 4, in the case of "N2+H2" shown by the dotted line and "NH3CVD" shown by the dashed line, a peak of absorbance appears at the position of the wavelength corresponding to h-BN. That is, it shows that nuclei 721 of boron nitride-containing material are formed on the substrate W by the processing in steps S101 to S105. In addition, when a deposition layer 710 of boron-containing material is formed on the substrate W with B2H6 and then nitrided with plasma of a processing gas containing a nitrogen-containing gas, "N2+H2" shown by the dotted line and "NH3CVD" shown by the dashed line show a higher reaction rate for forming h-BN than "N2CVD" shown by the dashed line.

[0051] Next, an example of a method for forming an h-BN film (substrate processing method) according to a reference example will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a flow chart showing an example of a method for forming an h-BN film according to a reference example. Fig. 6 is an example of a schematic cross-sectional view of a substrate W in each step according to the reference example.

[0052] In step S201, a substrate W is prepared. The substrate W has an underlayer 700 (see FIG. 6(a) described later). Here, the control unit 9 controls a transfer device (not shown) to place the substrate W on the mounting table 3 of the substrate processing apparatus 1. When the transfer device retreats from the transfer port 25, the control unit 9 closes the gate valve 26.

[0053] In step S202, plasma of Ar gas is ignited in the processing vessel 2. Here, the control unit 9 controls the valve of the gas source 61 and the like to supply Ar gas for generating plasma to the processing vessel 2. The control unit 9 also controls the RF power supply 51 to supply high frequency power for generating plasma to the upper electrode. As a result, plasma of Ar gas is ignited between the upper electrode (gas supply unit 5) and the lower electrode 33.

[0054] 6(a) is an example of a schematic cross-sectional view of the substrate W in step S202. An Ar gas plasma P1 is generated in the processing chamber 2. The substrate W is exposed to the Ar gas plasma P1.

[0055] In step S203, B2H6 gas (boron-containing gas) and NH3 gas (nitrogen-containing gas) are supplied to the processing vessel 2. Here, from a state in which the plasma P1 of Ar gas is formed, the control unit 9 controls the valve of the gas source 61 and the like to supply B2H6 gas and NH3 gas to the processing vessel 2. As a result, the substrate W in the processing vessel 2 is exposed to the plasma P5 of the processing gas according to the reference example containing B2H6 gas, NH3 gas, and Ar gas. As a result, a boron nitride film 725 is formed on the substrate W. Then, when a predetermined processing time has elapsed, the control unit 9 controls the valve of the gas source 61 and the like to stop the supply of B2H6 gas and NH3 gas to the processing vessel 2. In addition, the control unit 9 controls the RF power source 51 to stop the supply of high-frequency power to the upper electrode. In addition, the control unit 9 controls the valve of the gas source 61 and the like to stop the supply of Ar gas to the processing vessel 2.

[0056] 6(b) is an example of a schematic cross-sectional view of the substrate W in step S203. A plasma P5 of a process gas according to a reference example containing B2H6 gas, NH3 gas, and Ar gas is generated in the process vessel 2. As a result, a boron nitride film 725 is formed on the substrate W. Here, as described later, the boron nitride film 725 grows in the stacking direction and the surface direction.

[0057] 6(c) is an example of a schematic cross-sectional view of the substrate W after the process of step S203. The boron nitride film 725 is formed on the underlayer 700 of the substrate W by growing in the stacking direction and the surface direction of the substrate W.

[0058] Next, the method for forming an h-BN film according to this embodiment (see Figs. 2 and 3) will be further described in comparison with the method for forming an h-BN film according to a reference example (see Figs. 5 and 6). Fig. 7 is an example of a graph showing the relationship between a nitrogen-containing gas and a nitridation reaction. Here, each film formed on a substrate W was analyzed by Fourier transform infrared spectroscopy (FT-IR). The horizontal axis indicates wavelength (Wavenumber), and the vertical axis indicates absorbance (Absorbance).

[0059] The solid line "NH3 → N2" corresponds to the method of forming an h-BN film according to this embodiment (see Figures 2 and 3), in which a substrate W on which a deposition layer 710 of a boron-containing material has been formed using B2H6 is nitrided using plasma of a first process gas containing NH3 and Ar (see steps S103 and S104 in Figure 2), and then a boron nitride film 722 is formed on the substrate W using plasma of a second process gas containing B2H6, N2, and Ar (see step S105 in Figure 2).

[0060] The dashed line "NH3" corresponds to the method for forming an h-BN film according to the reference example (see Figures 5 and 6), in which a boron nitride film 725 was formed on a substrate W using plasma of a processing gas containing B2H6, NH3, and Ar (see steps S202 and S203 in Figure 5).

[0061] The dashed line indicates "N2" in the method for forming an h-BN film according to the reference example (see Figs. 5 and 6), in which the nitrogen-containing gas was changed from NH3 to N2. In other words, the dashed line indicates "N2", which corresponds to the method for forming an h-BN film according to another reference example, in which a boron nitride film was formed on a substrate W using plasma of a process gas containing B2H6, N2, and Ar.

[0062] As shown in FIG. 7, in the method for forming an h-BN film according to the present embodiment, the position of the wavelength corresponding to h-BN (see FIG. 4 , 1400 cm -1 A peak appears around 100 nm. This indicates that an h-BN film has been formed.

[0063] In the method for forming an h-BN film according to the reference example using NH3 as the nitrogen-containing gas, the wavelength position corresponding to h-BN (see FIG. 4) was 1400 cm -1 A peak appears around 100 nm. This indicates that an h-BN film has been formed.

[0064] On the other hand, in the method for forming an h-BN film according to another reference example using N2 as the nitrogen-containing gas, the wavelength position corresponding to h-BN (see FIG. 4 ) is 1400 cm -1 In other words, no h-BN film was formed.

[0065] Fig. 8 is a cross-sectional view showing a boron nitride film 722 formed by the h-BN film forming method according to this embodiment (see Figs. 2 and 3). Fig. 9 is a cross-sectional view showing a boron nitride film 725 formed by the h-BN film forming method according to a reference example (see Figs. 5 and 6).

[0066] 8, the process in step S104 was performed for 1 minute, and the process in step S105 was performed for 4 minutes to form the boron nitride film 722. Here, the boron nitride film 722 was formed in 3 to 5 layers with a thickness of 1.95 nm.

[0067] 9, the process of step S203 was performed for 5 minutes to deposit the boron nitride film 725. Here, the boron nitride film 725 was deposited in 7 to 8 layers with a thickness of 3.04 nm.

[0068] 8 and 9, a thin boron nitride film 722 can be formed on the substrate W according to the h-BN film forming method of this embodiment (see FIGS. 2 and 3).

[0069] That is, by separately performing the step (S102) of supplying a first boron-containing gas and the step (S104) of exposing to plasma of a first process gas containing a first nitrogen-containing gas, the thickness in the stacking direction of the nucleus 721 of the boron nitride-containing material formed on the substrate W can be suppressed.

[0070] 4 and 7, in the step (S105) of exposing the substrate W to plasma of the second process gas containing the second boron-containing gas and the second nitrogen-containing gas, a combination of gases that does not favorably grow a boron nitride film on the substrate W as is can be used. This allows a boron nitride film 722 to grow in the surface direction of the substrate W from nuclei 721 of the boron nitride-containing material. Meanwhile, the growth of the boron nitride film 722 in the stacking direction of the substrate W can be suppressed. This allows a thin boron nitride film 722 to be formed on the substrate W.

[0071] The substrate processing method for forming a boron nitride film has been described above, but the present disclosure is not limited to the above-described embodiments, and various modifications and improvements are possible within the scope of the gist of the present disclosure described in the claims. [Explanation of symbols]

[0072] W substrate 1. Substrate Processing Equipment 2. Treatment vessel 3. Placement table 5 Gas supply section 6 Gas supply line 9. Control Unit 51 RF power supply (plasma generation unit) 700 Base layer 710 Boron-containing deposits 721 Core containing boron nitride 722 Boron nitride film

Claims

1. Providing a substrate having an underlayer; exposing the substrate to a first boron-containing gas to form a boron-containing deposit layer on the substrate; exposing the substrate on which the boron-containing material deposition layer is formed to a plasma of a first process gas containing a first nitrogen-containing gas to nitridize the boron-containing material deposition layer to form boron nitride-containing nuclei; and exposing the substrate on which the boron nitride-containing nuclei have been formed to a plasma of a second process gas containing a second boron-containing gas and a second nitrogen-containing gas different from the first nitrogen-containing gas to form a boron nitride film on the substrate. A method for processing a substrate.

2. The step of forming the boron nitride film includes: growing the boron nitride film in a surface direction of the substrate from the nuclei of the boron nitride-containing material; The method of claim 1 .

3. The first nitrogen-containing gas is NH ３ , N ２ and H ２ and monomethylhydrazine. The substrate processing method according to claim 1 or 2.

4. The second nitrogen-containing gas is N ２ , N ２ and H ２ At least one of the mixed gases The substrate processing method according to claim 3 .

5. The first boron-containing gas and the second boron-containing gas are ２ H ６ , BCl ３ , B ３ N ３ H ６ , B(CH ３ ) ３ At least one of the gases The substrate processing method according to claim 4 .

6. The first boron-containing gas and the second boron-containing gas are different gases. The substrate processing method according to claim 4 .

7. After the step of forming a deposition layer of the boron-containing material and before the step of forming nuclei of the boron nitride-containing material, exposing the substrate to a plasma of an inert gas. The substrate processing method according to claim 1 or 2.

8. the first process gas and the second process gas include the inert gas; The substrate processing method according to claim 7 .

9. The inert gas is at least one of Ar and He. The substrate processing method according to claim 8 .

10. The underlayer is made of SiO ２ , HfO ２ , SiO ２ , HfO ２ , HfSiO ４ , HfSiON, ZrO ２ , amorphous silicon, or sapphire; The substrate processing method according to claim 1 or 2.

11. The step of forming a deposition layer of a boron-containing material includes: treating the substrate at a temperature in the range of 600°C to 900°C; The substrate processing method according to claim 1 or 2.

12. The step of forming the boron nitride-containing nuclei comprises: treating the substrate at a temperature in the range of 600°C to 900°C; The substrate processing method according to claim 1 or 2.

13. The step of forming the boron nitride film includes: treating the substrate at a temperature in the range of 600°C to 900°C; The substrate processing method according to claim 1 or 2.

14. The pressure in the step of forming nuclei of the boron nitride-containing material is equal to or higher than the pressure in the step of forming the boron nitride film. The substrate processing method according to claim 1 or 2.

15. The pressure in the step of forming the boron nitride-containing nuclei is Within the range of 10 mTorr to 200 mTorr; The substrate processing method according to claim 1 or 2.

16. The step of forming the boron nitride film includes: Within the range of 10 mTorr to 200 mTorr; The substrate processing method according to claim 1 or 2.

17. forming a deposition layer of the boron-containing material, forming nuclei of the boron nitride-containing material, and forming the boron nitride film constitute one cycle, and the cycle is repeated a number of times; The method of claim 1 .

18. A processing vessel; a mounting table provided in the processing chamber and configured to mount a substrate thereon; a gas supply unit that supplies a process gas; a plasma generating unit for generating plasma of the processing gas; A control unit, The control unit is exposing the substrate to a first boron-containing gas; exposing the substrate to a plasma of a first process gas comprising a first nitrogen-containing gas; exposing the substrate to a plasma of a second process gas comprising a second boron-containing gas and a second nitrogen-containing gas different from the first nitrogen-containing gas. Substrate processing equipment.

19. The first nitrogen-containing gas is NH ３ , N ２ and H ２ and monomethylhydrazine, The second nitrogen-containing gas is N ２ , N ２ and H ２ At least one of the mixed gases The first boron-containing gas and the second boron-containing gas are ２ H ６ , BCl ３ , B ３ N ３ H ６ , B(CH ３ ) ３ At least one of the gases The substrate processing apparatus of claim 18 .

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