Film formation method and film formation device

Abstract

A film formation method according to one embodiment of the present disclosure comprises: a step for preparing a substrate having an oxide film formed on the surface thereof; a step for forming a seed containing silicon, boron, and nitrogen on the oxide film by supplying a first silicon-containing gas, a boron-containing gas, and a first nitriding agent to the substrate; and a step for forming a nitride film on the oxide film having the seed formed thereon.

Description

Film deposition method and film deposition apparatus

[0001] This disclosure relates to a film deposition method and a film deposition apparatus.

[0002] Patent Document 1 discloses a technique for forming a SiOCN layer and a SiN film on a SiO film in that order.

[0003] Japanese Patent Application Publication No. 2017-28171

[0004] This disclosure provides a technology that can suppress the deterioration of the protective function of a nitride film.

[0005] A film-forming method according to one aspect of the present disclosure includes the steps of: preparing a substrate on which an oxide film is formed on its surface; supplying a first silicon-containing gas, a boron-containing gas, and a first nitride agent to the substrate to form a seed containing silicon, boron, and nitrogen on the oxide film; and forming a nitride film on the oxide film on which the seed has been formed.

[0006] According to this disclosure, it is possible to suppress the deterioration of the protective function of the nitride film.

[0007] This is a vertical cross-sectional view showing a film deposition apparatus according to an embodiment. This is a horizontal cross-sectional view showing a film deposition apparatus according to an embodiment. This is a flowchart showing a film deposition method according to an embodiment. This is a cross-sectional view (1) showing a film deposition method according to an embodiment. This is a cross-sectional view (2) showing a film deposition method according to an embodiment. This is a cross-sectional view (3) showing a film deposition method according to an embodiment. This is a diagram showing an example of a method for forming SiBN seeds. This is a diagram showing an example of a method for forming SiBCN seeds. This is a diagram showing an example of a method for forming a silicon nitride film. This is a diagram showing the relationship between the number of repetitions and the film thickness. This is a diagram showing the results of a pinhole test. This is a diagram showing the growth process of a silicon nitride film formed using DCS gas. This is a diagram showing the growth process of a silicon nitride film formed using HCD gas. This is a diagram showing the growth process of SiBN seeds.

[0008] Hereinafter, exemplary embodiments of the present disclosure, not limited to those described herein, will be described with reference to the attached drawings. In all attached drawings, identical or corresponding members or components are denoted by the same or corresponding reference numerals, and redundant descriptions are omitted.

[0009] [Film Deposition Apparatus] Figure 1 is a vertical cross-sectional view showing a film deposition apparatus 100 according to the embodiment. Figure 2 is a horizontal cross-sectional view showing a film deposition apparatus 100 according to the embodiment. The film deposition apparatus 100 comprises a processing container 1, a gas supply unit 20, a plasma generation unit 30, an exhaust unit 40, a heating unit 50, and a control unit 90.

[0010] The processing container 1 has a vertical, cylindrical shape with a ceiling that is open at the lower end. The processing container 1 is made of, for example, quartz. A ceiling plate 2 is provided near the upper end of the processing container 1, and the area below the ceiling plate 2 is sealed. The ceiling plate 2 is made of, for example, quartz. A cylindrical metal manifold 3 is connected to the opening at the lower end of the processing container 1 via a sealing member 4. The sealing member 4 is, for example, an O-ring.

[0011] The manifold 3 supports the lower end of the processing container 1. A boat 5 is inserted into the processing container 1 from below the manifold 3. The boat 5 holds multiple substrates W (for example, 25 to 150) in a substantially horizontal position with spacing along the vertical direction. The boat 5 is made of, for example, quartz. The boat 5 has, for example, three support columns 6, and the multiple substrates W are supported by grooves formed in the support columns 6. The substrates W are, for example, semiconductor substrates.

[0012] Boat 5 is placed on a turntable 8 via an insulating tube 7. The insulating tube 7 is made of, for example, quartz. The insulating tube 7 suppresses heat dissipation from the opening at the lower end of the manifold 3. The turntable 8 is supported on a rotating shaft 10. The opening at the lower end of the manifold 3 is opened and closed by a cover 9. The cover 9 is made of, for example, a metal material such as stainless steel. The rotating shaft 10 passes through the cover 9.

[0013] A magnetic fluid seal 11 is provided at the penetration portion of the rotating shaft 10. The magnetic fluid seal 11 airtightly seals the rotating shaft 10 and supports it so that it can rotate. Between the periphery of the lid 9 and the lower end of the manifold 3, a sealing member 12 is provided to maintain airtightness inside the processing container 1. The sealing member 12 is, for example, an O-ring.

[0014] The rotating shaft 10 is attached to the tip of an arm 13 supported by a lifting mechanism such as a boat elevator. As the arm 13 moves up and down, the boat 5, the insulation cylinder 7, the rotating base 8, and the lid 9 move up and down together with the rotating shaft 10, and are inserted into and removed from the processing container 1.

[0015] The gas supply unit 20 supplies various processing gases into the processing container 1. The gas supply unit 20 has a gas nozzle 21, a gas nozzle 25, and a gas nozzle 29. The gas nozzles 21, 25, and 29 are made of, for example, quartz. The gas supply unit 20 may further have other gas nozzles.

[0016] The gas nozzle 21 has an L-shape that penetrates the side wall of the manifold 3 inward, is bent upward, and extends vertically. The vertical portion of the gas nozzle 21 is provided inside the processing container 1. Multiple gas holes 21h are provided in the vertical portion of the gas nozzle 21. The multiple gas holes 21h are provided at predetermined intervals along the vertical axis of the gas nozzle 21. Each gas hole 21h is oriented, for example, towards the center CT of the processing container 1.

[0017] A flow path L1 is connected to the gas nozzle 21. In the flow path L1, a hexachlorodisilane (HCD) gas supply source G1, a flow controller F1, and a valve V1 are provided in order from the upstream side to the downstream side in the direction of gas flow. HCD gas is an example of a first silicon-containing gas. The HCD gas from the supply source G1 is supplied at a timing controlled by the valve V1 and adjusted to a predetermined flow rate by the flow controller F1. The HCD gas flows from the flow path L1 into the gas nozzle 21 and is discharged horizontally from a plurality of gas holes 21h toward the center CT of the processing container 1. The flow controller F1 is, for example, a mass flow controller.

[0018] A flow path L2 is connected downstream of valve V1 in flow path L1. Flow path L2 may be directly connected to the gas nozzle 21. In flow path L2, a dichlorosilane (DCS) gas supply source G2, a flow controller F2, and valve V2 are provided in order from upstream to downstream in the direction of gas flow. DCS gas is an example of a second silicon-containing gas. The supply timing of the DCS gas from supply source G2 is controlled by valve V2, and the flow rate is adjusted to a predetermined level by flow controller F2. The DCS gas flows from flow path L2 through flow path L1 to the gas nozzle 21 and is discharged horizontally from a plurality of gas holes 21h toward the center CT of the processing container 1. The flow controller F2 is, for example, a mass flow controller.

[0019] A flow path L3 is connected downstream of valve V1 in flow path L1. Flow path L3 may be directly connected to the gas nozzle 21. In flow path L3, from upstream to downstream in the direction of gas flow, boron trichloride (BCl) is supplied in order. ３ A gas supply source G3, a flow controller F3, and a valve V3 are provided. Boron trichloride gas is an example of a boron-containing gas. The supply timing of the boron trichloride gas from the supply source G3 is controlled by the valve V3, and the flow rate is adjusted to a predetermined level by the flow controller F3. The boron trichloride gas flows from the flow path L3 through the flow path L1 to the gas nozzle 21, and is discharged horizontally from a plurality of gas holes 21h toward the center CT of the processing container 1. The flow controller F3 is, for example, a mass flow controller.

[0020] A flow path L4 is connected downstream of valve V1 in flow path L1. Flow path L4 may be directly connected to gas nozzle 21. In flow path L4, ethylene (C) is supplied sequentially from upstream to downstream in the gas flow direction. ２ H ４A gas supply source G4, a flow controller F4, and a valve V4 are provided. Ethylene gas is an example of a carbon-containing gas. The supply timing of the ethylene gas from the supply source G4 is controlled by the valve V4, and the flow rate is adjusted to a predetermined level by the flow controller F4. The ethylene gas flows from the flow path L4 through the flow path L1 to the gas nozzle 21, and is discharged horizontally from a plurality of gas holes 21h toward the center CT of the processing container 1. The flow controller F4 is, for example, a mass flow controller.

[0021] The gas nozzle 25 has an L-shape that penetrates the side wall of the manifold 3 inward, is bent upward, and extends vertically. The vertical portion of the gas nozzle 25 is provided in the plasma generation space P. Multiple gas holes 25h are provided in the vertical portion of the gas nozzle 25. The multiple gas holes 25h are provided at predetermined intervals along the vertical axis of the gas nozzle 25. Each gas hole 25h is oriented, for example, toward the center CT of the processing container 1.

[0022] A flow path L5 is connected to the gas nozzle 25. In the flow path L5, ammonia (NH4H4) is supplied sequentially from the upstream side to the downstream side in the direction of gas flow. ３ A gas supply source G5, a flow controller F5, and a valve V5 are provided. Ammonia gas is an example of a first nitride agent and a second nitride agent. The supply timing of the ammonia gas from the supply source G5 is controlled by the valve V5, and the flow rate is adjusted to a predetermined level by the flow controller F5. The ammonia gas flows from the flow path L5 into the gas nozzle 25 and is discharged horizontally from a plurality of gas holes 25h toward the center CT of the processing container 1.

[0023] The gas nozzle 29 has a straight pipe shape that extends horizontally through the side wall of the manifold 3. The tip of the gas nozzle 29 is located inside the processing container 1. The tip of the gas nozzle 29 is open.

[0024] A flow path L9 is connected to the gas nozzle 29. In the flow path L9, nitrogen (N) is supplied sequentially from the upstream to the downstream direction of gas flow. ２A gas supply source G9, a flow controller F9, and a valve V9 are provided. Nitrogen gas is an example of an inert gas. The supply timing of the nitrogen gas from the supply source G9 is controlled by the valve V9, and the flow rate is adjusted to a predetermined level by the flow controller F9. The nitrogen gas flows from the flow path L9 into the gas nozzle 29 and is discharged into the processing container 1 from the opening at the tip.

[0025] The plasma generation unit 30 is provided in a part of the side wall of the processing container 1. The plasma generation unit 30 generates plasma from ammonia gas supplied from the gas nozzle 25. The plasma generation unit 30 includes a plasma compartment wall 32, a pair of plasma electrodes 33, a power supply line 34, an RF power supply 35, and an insulating protective cover 36.

[0026] The plasma compartment wall 32 is airtightly welded to the outer wall of the processing vessel 1. The plasma compartment wall 32 is made of, for example, quartz. The plasma compartment wall 32 has a concave cross-section and covers the opening 31 formed in the side wall of the processing vessel 1. The opening 31 is formed to be elongated in the vertical direction so as to cover all the substrates W supported by the boat 5 in the vertical direction. The plasma compartment wall 32 defines the plasma generation space P, which is an inner space communicating with the inside of the processing vessel 1.

[0027] Each of the pair of plasma electrodes 33 has an elongated shape and is arranged facing each other in the vertical direction on the outer surfaces of the walls on both sides of the plasma compartment wall 32. A power supply line 34 is connected to the lower end of each plasma electrode 33.

[0028] The power supply line 34 electrically connects each plasma electrode 33 to the RF power supply 35. For example, one end of the power supply line 34 is connected to the lower end, which is the side of the short edge of each plasma electrode 33, and the other end is connected to the RF power supply 35.

[0029] The RF power supply 35 is electrically connected to the lower end of each plasma electrode 33 via a power supply line 34. The RF power supply 35 supplies RF power of, for example, 13.56 MHz to the pair of plasma electrodes 33. This applies RF power to the plasma generation space P defined by the plasma partition wall 32.

[0030] The insulating protective cover 36 is attached to the outside of the plasma compartment wall 32 so as to cover the plasma compartment wall 32. A coolant passage (not shown) is provided in the inner portion of the insulating protective cover 36. The plasma electrode 33 is cooled by flowing a coolant such as cooled nitrogen gas through the coolant passage. A shield (not shown) may be provided between the plasma electrode 33 and the insulating protective cover 36 so as to cover the plasma electrode 33. The shield is made of a good conductor such as metal and is electrically grounded.

[0031] The exhaust section 40 has an exhaust port 41. The exhaust port 41 is provided on the side wall portion of the processing container 1. The exhaust port 41 is positioned opposite the opening 31. The exhaust port 41 is formed to be long and narrow vertically, corresponding to the boat 5. A cover member 42, formed in a U-shape in cross-section, is attached to the portion of the processing container 1 corresponding to the exhaust port 41. The cover member 42 extends upward along the side wall of the processing container 1. An exhaust pipe 43 is connected to the lower part of the cover member 42. A pressure regulating valve 44 and a vacuum pump 45 are provided on the exhaust pipe 43 in order from upstream to downstream in the direction of gas flow. The pressure regulating valve 44 adjusts the pressure inside the processing container 1. The vacuum pump 45 discharges the gas inside the processing container 1.

[0032] The heating section 50 includes a heater 51. The heater 51 has a cylindrical shape that surrounds the processing container 1 on its radially outer side. The heater 51 heats each substrate W housed inside the processing container 1 by heating the entire side circumference of the processing container 1.

[0033] The control unit 90 is an electronic circuit such as a CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit). The control unit 90 performs various control operations described in this specification by executing instruction codes stored in memory or by circuit design for special applications.

[0034] [Film Formation Method] FIG. 3 is a flowchart showing the film formation method according to the embodiment. FIGS. 4 to 6 are cross-sectional views illustrating the film formation method according to the embodiment. The film formation method according to the embodiment includes steps S101 to S103 shown in FIG. 3.

[0035] In step S101, a substrate W is prepared. As shown in FIG. 4, the substrate W has an oxide film 101 on a surface thereof. The oxide film 101 is a single-layer film. The oxide film 101 may be a laminated film. The oxide film 101 is, for example, silicon oxide (SiO ２ ) film.

[0036] In step S102, the control unit 90 raises the arm 13 to carry the boat 5 holding the plurality of substrates W into the processing container 1, and hermetically closes and seals the opening at the lower end of the processing container 1 with the lid 9. Next, as shown in FIG. 5, the control unit 90 controls the film formation apparatus 100 to form a seed 102 containing silicon (Si), boron (B), and nitrogen (N) on the oxide film 101. The seed 102 is an SiBN seed. The seed may be an SiBCN seed.

[0037] FIG. 7 is a diagram showing an example of a method for forming an SiBN seed. The control unit 90 controls the film formation apparatus 100 to execute steps S201 to S208 shown in FIG. 7. Accordingly, an SiBN seed is formed on the oxide film 101. During the execution of steps S201 to S208, the control unit 90 controls the heating unit 50 such that the temperature of each substrate W in the processing container 1 reaches a temperature at which a nitriding reaction caused by ammonia gas occurs (e.g., 600° C. or higher).

[0038] In step S201, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 such that supplying nitrogen gas into the processing container 1 and exhausting the inside of the processing container 1 are performed simultaneously or non-simultaneously. Accordingly, the inside of the processing container 1 is purged.

[0039] In step S202, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to supply HCD gas into the processing container 1 while exhausting the inside of the processing container 1 for a predetermined period of time. Accordingly, HCD is adsorbed onto the oxide film 101 of each substrate W accommodated in the processing container 1. Since HCD is a silicon compound having Si-Si bonds, it is easily adsorbed onto the oxide film 101. Therefore, the number of repetitions required from the start of repetition of step S201 to step S207 until the start of SiBN film formation can be reduced, and productivity is improved.

[0040] In step S203, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to supply nitrogen gas into the processing container 1 and exhaust the inside of the processing container 1, either simultaneously or non-simultaneously. Accordingly, the inside of the processing container 1 is purged.

[0041] In step S204, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to supply boron trichloride gas into the processing container 1 while exhausting the inside of the processing container 1 for a predetermined period of time. Accordingly, boron trichloride is adsorbed onto the oxide film 101 of each substrate W accommodated in the processing container 1.

[0042] In step S205, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to stop the supply of boron trichloride gas into the processing container 1 and stop the exhaust inside the processing container 1. Further, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to maintain the state where the supply of boron trichloride gas into the processing container 1 is stopped and the exhaust inside the processing container 1 is stopped for a predetermined period of time. Accordingly, the state where boron trichloride gas is confined inside the processing container 1 is maintained (held). As a result, adsorption of boron trichloride onto the oxide film 101 is promoted, and the boron concentration in the SiBN seed can be increased.

[0043] In step S206, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to supply nitrogen gas into the processing container 1 and exhaust the inside of the processing container 1, either simultaneously or non-simultaneously. Accordingly, the inside of the processing container 1 is purged.

[0044] In step S207, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to supply ammonia gas into the processing container 1 while exhausting the inside of the processing container 1 for a predetermined time. As a result, the ammonia gas, activated by heat, nitrides the HCD and boron trichloride adsorbed on the oxide film 101 of each substrate W contained in the processing container 1. When thermal nitriding is performed, the nitriding of the underlying oxide film 101 can be suppressed. However, plasma nitriding may be performed instead of thermal nitriding.

[0045] In step S208, the control unit 90 determines whether steps S201 to S207 have been performed a first time. In step S208, if the control unit 90 determines that steps S201 to S207 have not been performed a first time (NO in step S208), it returns to step S201. In step S208, if the control unit 90 determines that steps S201 to S207 have been performed a first time (YES in step S208), it terminates the process. The first time is, for example, two or more times. The first time may be just one time.

[0046] Figure 8 shows an example of a method for forming SiBCN seeds. The control unit 90 controls the film deposition apparatus 100 to execute steps S301 to S311 shown in Figure 8. As a result, SiBCN seeds are formed on the oxide film 101. During the execution of steps S301 to S311, the control unit 90 controls the heating unit 50 so that the temperature of each substrate W in the processing container 1 reaches a temperature at which a nitriding reaction by ammonia gas occurs (for example, 600°C or higher).

[0047] Steps S301 to S306 are the same as steps S201 to S206.

[0048] In step S307, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to supply ethylene gas into the processing container 1 while exhausting the inside of the processing container 1 for a predetermined time. As a result, ethylene is adsorbed onto the oxide film 101 of each substrate W housed in the processing container 1.

[0049] In step S308, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to stop the supply of ethylene gas into the processing container 1 and to stop the exhaust of the processing container 1. The control unit 90 also controls the gas supply unit 20 and the exhaust unit 40 to maintain the state in which the supply of ethylene gas into the processing container 1 and the exhaust of the processing container 1 are stopped for a predetermined time. As a result, the state in which the ethylene gas is confined within the processing container 1 is maintained (held). Consequently, the adsorption of ethylene onto the oxide film 101 is promoted, and the carbon concentration in the SiBCN seed can be increased.

[0050] In step S309, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to supply nitrogen gas into the processing container 1 and to exhaust the processing container 1, either simultaneously or not simultaneously. As a result, the processing container 1 is purged.

[0051] In step S310, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to supply ammonia gas into the processing container 1 while exhausting the inside of the processing container 1 for a predetermined time. As a result, the ammonia gas, which has been activated by heat, nitrides the HCD, boron trichloride, and ethylene adsorbed on the oxide film 101 of each substrate W contained in the processing container 1. By performing thermal nitriding, the nitriding of the underlying oxide film 101 can be suppressed. However, plasma nitriding may be performed instead of thermal nitriding.

[0052] In step S311, the control unit 90 determines whether steps S301 to S310 have been performed a second time. In step S311, if the control unit 90 determines that steps S301 to S310 have not been performed a second time (NO in step S311), it returns to step S301. In step S311, if the control unit 90 determines that steps S301 to S310 have been performed a second time (YES in step S311), it terminates the process. The second time is, for example, two or more times. The second time may be just one time.

[0053] In step S103, as shown in Figure 6, the control unit 90 controls the film deposition apparatus 100 to form a nitride film 103 on the oxide film 101 on which the seed 102 is formed. The nitride film 103 is, for example, a silicon nitride (SiN) film.

[0054] Figure 9 shows an example of a method for forming a silicon nitride film. The control unit 90 controls the film deposition apparatus 100 to execute steps S401 to S405 shown in Figure 9. This forms a silicon nitride film on the seed 102. During the execution of steps S401 to S405, the control unit 90 controls the heating unit 50 so that, for example, the temperature of each substrate W in the processing container 1 is the same as the temperature of each substrate W when the seed 102 is formed. In this case, a silicon nitride film can be formed on the oxide film 101 on which the seed 102 is formed without changing the temperature of each substrate W after the seed 102 has been formed. However, during the execution of steps S401 to S405, the control unit 90 may control the heating unit 50 so that the temperature of each substrate W in the processing container 1 is different from the temperature of each substrate W when the seed 102 is formed. The temperature of each substrate W during the execution of steps S401 to S405 is preferably 550°C or higher. In this case, a dense silicon nitride film can be formed. The temperature of each substrate W during the execution of steps S401 to S405 is more preferably 600°C or higher. In this case, the temperature of each substrate W when forming the silicon nitride film can be set to the same as the temperature of each substrate W when forming the seed 102.

[0055] In step S401, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to supply nitrogen gas into the processing container 1 and to exhaust the processing container 1, either simultaneously or not simultaneously. As a result, the processing container 1 is purged.

[0056] In step S402, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to supply DCS gas into the processing container 1 while exhausting the inside of the processing container 1 for a predetermined time. As a result, DCS is adsorbed onto the oxide film 101 of each substrate W housed in the processing container 1.

[0057] In step S403, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to supply nitrogen gas into the processing container 1 and to exhaust the processing container 1, either simultaneously or not simultaneously. As a result, the processing container 1 is purged.

[0058] In step S404, the control unit 90 controls the gas supply unit 20 and the exhaust unit 40 to supply ammonia gas into the processing container 1 while exhausting the inside of the processing container 1 for a predetermined time. The control unit 90 also controls the plasma generation unit 30 to generate plasma from the ammonia gas supplied into the processing container 1. As a result, the DCS adsorbed on the oxide film 101 of each substrate W housed in the processing container 1 is nitrided by the plasma generated from the ammonia gas. Plasma nitriding can form a dense silicon nitride film. However, thermal nitriding may be performed instead of plasma nitriding.

[0059] In step S405, the control unit 90 determines whether steps S401 to S404 have been performed a third time. In step S405, if the control unit 90 determines that steps S401 to S404 have not been performed a third time (NO in step S405), it returns the process to step S401. In step S405, if the control unit 90 determines that steps S401 to S404 have been performed a third time (YES in step S405), it terminates the process. The third number of times is set according to the target thickness of the silicon nitride film. The third number of times is, for example, two or more. The third number of times may be one.

[0060] After step S103, the control unit 90 controls the gas supply unit 20, exhaust unit 40, and heating unit 50 to increase the pressure inside the processing container 1 to atmospheric pressure and then lower the temperature inside the processing container 1 to the discharge temperature. Next, the control unit 90 lowers the arm 13 to discharge the boat 5 from inside the processing container 1. With this, the processing of the multiple substrates W held in the boat 5 is completed.

[0061] As described above, according to the film formation method of the embodiment, a seed 102 containing silicon, boron, and nitrogen is formed on the oxide film 101, and a nitride film 103 is formed on the oxide film 101 on which the seed 102 is formed. The seed 102 containing silicon, boron, and nitrogen has the function of suppressing the diffusion of oxygen. Therefore, the diffusion of oxygen (O) in the oxide film 101 into the nitride film 103 can be suppressed. As a result, the deterioration of the protective film function of the nitride film 103 can be suppressed.

[0062] [Experimental Results] (Incubation Cycle) The experimental results evaluating the incubation cycles of SiBN seeds, SiBCN seeds, and silicon nitride films are described below. The incubation cycle for SiBN seeds refers to the number of repetitions required from the start of the repetition of steps S201 to S207 shown in Figure 7 until the formation of the SiBN seed film begins. The incubation cycle for SiBCN seeds refers to the number of repetitions required from the start of the repetition of steps S301 to S310 shown in Figure 8 until the formation of the SiBCN seed film begins. The incubation cycle for silicon nitride films refers to the number of repetitions required from the start of the repetition of steps S401 to S404 shown in Figure 9 until the formation of the silicon nitride film begins.

[0063] First, a silicon substrate with a silicon oxide film formed on its surface was prepared.

[0064] Next, SiBN seeds, SiBCN seeds, or a silicon nitride film were formed on the silicon oxide film. SiBN seeds were formed using the method for forming SiBN seeds shown in Figure 7. The first number of repetitions in step S208 of Figure 7 was set to 20, 30, or 40. SiBCN seeds were formed using the method for forming SiBCN seeds shown in Figure 8. The second number of repetitions in step S311 of Figure 8 was set to 20, 30, or 40. The silicon nitride film was formed using the method for forming silicon nitride film shown in Figure 9. The third number of repetitions in step S405 of Figure 9 was set to 40, 50, or 60.

[0065] Next, the film thicknesses of the SiBN seeds, SiBCN seeds, and silicon nitride film were measured.

[0066] Figure 10 shows the relationship between the number of repetitions and the film thickness. In Figure 10, the horizontal axis represents the number of repetitions [times], and the vertical axis represents the film thickness [Å]. In Figure 10, circles represent the results for SiBN seeding, squares represent the results for SiBCN seeding, and triangles represent the results for silicon nitride filming.

[0067] As shown in Figure 10, the incubation cycles for SiBN seeds and SiBCN seeds are fewer than those for silicon nitride films. This result indicates that SiBN seeds and SiBCN seeds can be deposited on silicon oxide films with fewer cycles than silicon nitride films.

[0068] (Pinhole Test) This section describes the experimental results of evaluating the protective function of silicon nitride films using a pinhole test.

[0069] First, a silicon substrate with a silicon oxide film formed on its surface was prepared.

[0070] Next, SiBN seeds or SiBCN seeds were formed on the silicon oxide film. SiBN seeds were formed using the method shown in Figure 7. The first number of repetitions in step S208 of Figure 7 was set to 10 or 15. SiBCN seeds were formed using the method shown in Figure 8. The second number of repetitions in step S311 of Figure 8 was set to 5. For comparison, a sample was also prepared in which no seeds were formed on the silicon oxide film.

[0071] Next, a silicon nitride film was formed on a silicon oxide film on which SiBN seeds were formed, a silicon oxide film on which SiBCN seeds were formed, or a silicon oxide film on which no seeds were formed. Here, silicon nitride films with multiple film thicknesses were formed.

[0072] Next, the surface of the silicon nitride film was exposed to dilute hydrofluoric acid (DHF) for 60 seconds. At this time, if there are pinholes in the silicon nitride film, the silicon oxide film directly beneath the pinholes is etched by the DHF, creating cavities in the silicon oxide film that are larger than the pinholes.

[0073] Next, the presence or absence of pinholes was checked using a scanning electron microscope (SEM). At this time, the presence or absence of pinholes in the silicon nitride film was determined by observing the cavities formed in the silicon oxide film using the SEM. In the pinhole test, if one or more pinholes were detected, it was determined that the silicon nitride film contained pinholes.

[0074] Figure 11 shows the results of the pinhole test. In Figure 11, the thickness [Å] of the silicon nitride film in samples determined to be pinhole-free is indicated by a black diamond, and the thickness [Å] of the silicon nitride film in samples determined to be pinhole-free is indicated by a white diamond.

[0075] As shown in Figure 11, when a silicon nitride film was formed on a silicon oxide film without forming a seed (see "No Seed" in Figure 11), no pinholes occurred when the silicon nitride film thickness was 21.9 Å or greater. In contrast, pinholes occurred when the silicon nitride film thickness was 20.6 Å or less.

[0076] As shown in Figure 11, when a silicon nitride film was formed after forming SiBN seeds on a silicon oxide film (see "With SiBN seeds (First time: 10 times)" in Figure 11), no pinholes occurred when the silicon nitride film thickness was 18.6 Å or more. In contrast, pinholes occurred when the silicon nitride film thickness was 17.2 Å or less.

[0077] As shown in Figure 11, when a silicon nitride film was formed after forming SiBN seeds on a silicon oxide film (see "With SiBN seeds (First time: 15 times)" in Figure 11), no pinholes occurred when the silicon nitride film thickness was 18.5 Å or more. In contrast, pinholes occurred when the silicon nitride film thickness was 16.6 Å or less.

[0078] As shown in Figure 11, when a silicon nitride film was formed after forming SiBCN seeds on a silicon oxide film (see "SiBCN seeds present (second iteration: 5 times)" in Figure 11), no pinholes occurred when the silicon nitride film thickness was 19.2 Å or more. In contrast, pinholes occurred when the silicon nitride film thickness was 17.8 Å or less.

[0079] The results above demonstrate that by forming SiBN seeds or SiBCN seeds on a silicon oxide film before forming a silicon nitride film, the thickness of the silicon nitride film can be reduced without generating pinholes.

[0080] [Discussion] This section explains why forming a silicon nitride film after forming SiBN seeds on a silicon oxide film results in a film that is less prone to pinhole formation.

[0081] Figure 12 shows the growth process of a silicon nitride film formed using DCS gas. Consider the case where DCS gas is supplied to the surface of a silicon oxide film, as shown in Figure 12(a). DCS does not readily adsorb to the surface of a silicon oxide film. Therefore, when DCS gas is supplied to the surface of a silicon oxide film, it is thought that DCS will adsorb to the surface of the silicon oxide film in an island-like manner at a low density, as shown in Figure 12(b). If the supply of DCS gas to the surface of the silicon oxide film is continued, it is thought that DCS will adsorb with a high surface roughness, as shown in Figure 12(c). After this, if the DCS is nitrided, it is thought that a silicon nitride film with a high surface roughness will be formed. As a result, it is thought that a silicon nitride film prone to pinholes will be formed.

[0082] Figure 13 shows the growth process of a silicon nitride film formed using HCD gas. Consider the case where HCD gas is supplied to the surface of a silicon oxide film, as shown in Figure 13(a). HCD is more easily adsorbed to the surface of a silicon oxide film than DCS. Therefore, when HCD gas is supplied to the surface of a silicon oxide film, it is thought that HCD will be adsorbed in a dense, island-like manner on the surface of the silicon oxide film, as shown in Figure 13(b). If the supply of HCD gas to the surface of the silicon oxide film is continued, it is thought that HCD will be adsorbed with a relatively small surface roughness, as shown in Figure 13(c). After this, if the HCD is nitrided, it is thought that a silicon nitride film with a relatively small surface roughness will be formed. As a result, it is thought that by using HCD, a silicon nitride film that is less prone to pinholes can be formed than when using DCS.

[0083] Figure 14 shows the growth process of SiBN seeds. Consider the case where HCD gas and boron trichloride gas are supplied to the surface of a silicon oxide film, as shown in Figure 14(a). HCD is more easily adsorbed to the surface of a silicon oxide film than DCS. Therefore, when HCD gas is supplied to the surface of a silicon oxide film, it is thought that HCD is adsorbed in a dense, island-like manner on the surface of the silicon oxide film, as shown in Figure 14(b). Boron trichloride has a planar structure. Therefore, as shown in Figure 14(b), it is thought that boron trichloride is adsorbed complementarily to the unadsorbed sites of the island-like adsorbed HCD. If the supply of HCD gas and boron trichloride gas to the surface of the silicon oxide film is continued, it is thought that HCD and boron trichloride are adsorbed with a very low surface roughness, as shown in Figure 14(c). After this, if HCD and boron trichloride are nitrided, it is thought that SiBN seeds with a very low surface roughness are formed. Furthermore, when a silicon nitride film is formed on top of a SiBN seed, a silicon nitride film with very low surface roughness is formed, and as a result, a silicon nitride film that is less prone to pinhole formation is thought to be formed.

[0084] It should be understood that the embodiments disclosed herein are illustrative in all respects and not restrictive. The above embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0085] In the above embodiment, the case where the film forming apparatus is a batch-type apparatus that processes a plurality of substrates at once has been described, but the present disclosure is not limited thereto. For example, the film forming apparatus may be a single-wafer type apparatus that processes substrates one by one.

[0086] In the above embodiment, the case where the first silicon-containing gas is HCD gas has been described, but the present disclosure is not limited thereto. As the first silicon-containing gas, for example, silicon halide having an Si-Si bond such as HCD gas, hexabromodisilane gas, or a combination thereof can be used.

[0087] In the above embodiment, the case where the second silicon-containing gas is DCS gas has been described, but the present disclosure is not limited thereto. The second silicon-containing gas may contain silicon halide. As the silicon halide, for example, DCS, HCD, tetrachlorosilane, trichlorosilane, or a combination thereof can be used. The second silicon-containing gas may be the same gas as the first silicon-containing gas.

[0088] In the above embodiment, the case where the boron-containing gas is boron trichloride gas has been described, but the present disclosure is not limited thereto. As the boron-containing gas, for example, borane (BH ３ ) gas, boron trichloride (BCl ３ ) gas, boron tribromide (BBr ３ ) gas, boron triiodide (BI ３ ) gas, borazine, or a combination thereof can be used.

[0089] In the above embodiment, the case where the carbon-containing gas is ethylene gas has been described, but the present disclosure is not limited thereto. The carbon-containing gas is C ｘ H ｙ gas, wherein x and y are integers of 1 or more. C ｘ H ｙ As the gas, for example, ethylene (C ２ H４ ) Gas, propane (C ３ H ８ ) Gas, or a combination thereof, can be used.

[0090] In the embodiments described above, the case in which the first and second nitriders are ammonia gas has been explained, but the disclosure is not limited thereto. For example, the first and second nitriders can be ammonia gas, diazene gas, hydrazine gas, monomethylhydrazine gas, trimethylamine gas, or a combination thereof.

[0091] In the embodiments described above, the case where the inert gas is nitrogen gas was explained, but this disclosure is not limited thereto. The inert gas may be a noble gas such as argon (Ar) gas.

[0092] This international application claims priority based on Japanese Patent Application No. 2025-049772, filed on 25 March 2025, and the entire contents of said application are incorporated herein by reference.

[0093] 101 Oxide film 102 Seed 103 Nitride film W Substrate

Claims

1. A film formation method comprising: preparing a substrate on which an oxide film is formed on its surface; supplying a first silicon-containing gas, a boron-containing gas, and a first nitride agent to the substrate to form a seed containing silicon, boron, and nitrogen on the oxide film; and forming a nitride film on the oxide film on which the seed has been formed.

2. The film-forming method according to claim 1, wherein the step of forming the seed comprises: (a) supplying the first silicon-containing gas to the substrate; (b) supplying the boron-containing gas to the substrate; (c) supplying the first nitride agent to the substrate after activating it by heat; and (d) repeating steps (a), (b), and (c).

3. The film-forming method according to claim 1, wherein the step of forming the seed comprises: (a) supplying the first silicon-containing gas to the substrate; (b) supplying the boron-containing gas to the substrate; (c) supplying the carbon-containing gas to the substrate; (e) supplying the first nitride agent to the substrate after activating it by heat; and (f) repeating steps (a), (b), (c), and (e).

4. The film formation method according to claim 1, wherein the step of forming the nitride film comprises: (g) supplying a second silicon-containing gas to the substrate; (h) supplying a second nitride agent to the substrate after activating it with plasma; and (i) repeating steps (g) and (h).

5. The film formation method according to any one of claims 1 to 4, wherein the first silicon-containing gas comprises a silicon compound having a Si-Si bond.

6. The film formation method according to claim 5, wherein the silicon compound is hexachlorodisilane.

7. The film formation method according to any one of claims 1 to 4, wherein the boron-containing gas comprises a boron compound having a planar structure.

8. The method for forming a film according to claim 7, wherein the boron compound is boron trichloride.

9. The film formation method according to claim 4, wherein the second silicon-containing gas contains silicon halide.

10. The film formation method according to claim 9, wherein the silicon halide is dichlorosilane.

11. A film deposition apparatus comprising: a processing container; and a control unit configured to control the film deposition apparatus, wherein the control unit controls the film deposition apparatus to perform the following steps: 1) placing a substrate on which an oxide film has been formed on its surface into the processing container; 2) supplying a first silicon-containing gas, a boron-containing gas, and a first nitride agent to the substrate to form a seed containing silicon, boron, and nitrogen on the oxide film; and 3) forming a nitride film on the oxide film on which the seed has been formed.

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