Substrate processing methods, semiconductor device manufacturing methods, processes, and substrate processing apparatus

Abstract

This invention relates to a substrate processing method, a semiconductor device manufacturing method, a recording medium, and a substrate processing apparatus. It provides a technique for controlling variations in etch resistance occurring near the interface with the substrate during the formation of a film on the substrate. The technique includes: (a) a step of forming a carbon-containing intermediate layer on a first film formed on the substrate; and (b) a step of forming a nitrogen-containing second film on the aforementioned intermediate layer using an activated nitrogen-containing gas. In step (a), the intermediate layer is formed in such a manner that the carbon content per unit area contained in the intermediate layer differs in the central region and the outer region of the substrate surface.

Description

Substrate processing method, method for manufacturing a semiconductor device, program, and substrate processing apparatus The present invention relates to a substrate processing method, a method for manufacturing a semiconductor device, a program, and a substrate processing apparatus. As one step in the manufacturing process of a semiconductor device, a process of supplying a processing gas to a substrate to form a film on the substrate is sometimes performed (for example, see Patent Document 1). [Prior Art Documents] [Patent Documents] [Patent Document 1] International Publication No. 2015 / 199111 [Problems to be Solved by the Invention] However, when forming a film, characteristics such as etching resistance sometimes change near the interface between the substrate and the film. It is sometimes required to suppress the occurrence of such characteristic changes, or to control the thickness distribution of such a layer (hereinafter referred to as a "transition layer") in the plane of the substrate even when a layer with changed characteristics is formed. The present invention provides a technique in which, when forming a film, it is possible to suppress the occurrence of changes in characteristics such as etching resistance that occur near the interface between the substrate and the film, or to control the thickness distribution of the transition layer in the plane of the substrate even when a transition layer is formed. [Technical Means for Solving the Problem] According to one aspect of the present invention, there is provided a technique including: (a) a step of forming an intermediate layer containing carbon on a first film formed on a substrate; (b) a step of forming a second film containing nitrogen using an activated nitrogen-containing gas on the intermediate layer, wherein in (a), the intermediate layer is formed such that the carbon content per unit area contained in the intermediate layer is different between the central region and the outer region in the plane of the substrate. [Effects of the Invention] According to the present invention, when forming a film, it is possible to suppress the occurrence of changes in characteristics such as etching resistance that occur near the interface between the substrate and the film, or to control the thickness distribution of the transition layer in the plane of the substrate even when a transition layer is formed. <One Aspect of the Present Invention> Hereinafter, one aspect of the present invention will be mainly described with reference to FIGS. 1 to 5. It should be noted that the drawings used in the following description are all schematic, and the dimensional relationships of the respective elements shown in the drawings, the ratios of the respective elements, etc. are not necessarily the same as in reality. In addition, the dimensional relationships of the respective elements and the ratios of the respective elements are not necessarily the same among the multiple drawings. (1) Structure of the substrate processing apparatus As shown in FIG. 1, the processing furnace 202 has a heater 207 as a heating mechanism (temperature adjustment unit). As will be described later, the heater 207 also functions as an activation mechanism (excitation unit) for activating (exciting) a gas by heat. Inside the heater 207, a reaction tube 203 that forms a reaction vessel (processing vessel) is arranged in a concentric circle with the heater 207. The reaction tube 203 is formed in a cylindrical shape with a closed upper end and an open lower end. A processing chamber 201 is formed in the cylindrical hollow portion of the reaction tube 203. The processing chamber 201 is configured to accommodate wafers 200 as substrates in a horizontally arranged state in multiple layers in the vertical direction by a susceptor 217 described later. Inside the processing chamber 201, nozzles 249a and 249b are provided so as to penetrate the lower part of the reaction tube 203. Gas supply tubes 232a and 232b are respectively connected to the nozzles 249a and 249b. A gas supply tube 232c is connected to the gas supply tube 232b. In this way, two nozzles 249a and 249b and three gas supply tubes 232a to 232c are provided on the reaction tube 203, and a variety of gases can be supplied into the processing chamber 201. On the gas supply tubes 232a to 232c, mass flow controllers (MFCs) 241a to 241c as flow controllers (flow control units) and valves 243a to 243c as on-off valves are respectively provided in sequence from the upstream direction. A gas supply tube 232d for supplying an inert gas is connected to the downstream side of the valve 243a in the gas supply tube 232a. In addition, a gas supply tube 232e for supplying an inert gas is connected to the downstream side of the connection portion of the gas supply tube 232b and the gas supply tube 232c. On the gas supply tubes 232d and 232e, MFCs 241d and 241e and valves 243d and 243e are respectively provided in sequence from the upstream direction. A nozzle 249a is connected to the front end of the gas supply tube 232a. As shown in FIG. 2, the nozzle 249a is arranged in a space that is annular in plan view between the inner wall of the reaction tube 203 and the wafer 200 so as to stand up from the lower part to the upper part of the inner wall of the reaction tube 203 in the loading direction of the wafer 200. Gas supply holes 250a for supplying gas are provided on the side surface of the nozzle 249a. The gas supply holes 250a are opened so as to face the center of the reaction tube 203, and can supply gas to the wafer 200. A plurality of gas supply holes 250a are provided from the lower part to the upper part of the reaction tube 203, each having the same opening area, and further arranged at the same opening interval. A nozzle 249b is connected to the front end of the gas supply pipe 232b. The nozzle 249b is disposed in a buffer chamber 237 which serves as a gas dispersion space. The buffer chamber 237 is formed between the inner wall of the reaction tube 203 and the partition wall 237a. As shown in FIG. 2, the buffer chamber 237 (partition wall 237a) is disposed in a space which is annular in plan view between the inner wall of the reaction tube 203 and the wafer 200 along the loading direction of the wafer 200, and is disposed in a portion from the lower part to the upper part of the inner wall of the reaction tube 203. At the end of the surface of the partition wall 237a opposite to (adjacent to) the wafer 200, a gas supply hole 250c for supplying gas is provided. The gas supply hole 250c is opened so as to face the center of the reaction tube 203, and can supply gas toward the wafer 200. A plurality of gas supply holes 250c are provided from the lower part to the upper part of the reaction tube 203, each having the same opening area, and further are provided at the same opening interval. The nozzle 249b is disposed at the end of the buffer chamber 237 opposite to the end where the gas supply hole 250c is provided, and stands up from the lower part to the upper part of the inner wall of the reaction tube 203 in the upward direction of the loading direction of the wafer 200. A gas supply hole 250b for supplying gas is provided on the side surface of the nozzle 249b. The gas supply hole 250b is opened so as to face the center of the buffer chamber 237. The gas supply hole 250b is also provided in a plurality from the lower part to the upper part of the reaction tube 203, like the gas supply hole 250c. The gas ejected into the buffer chamber 237 from the gas supply hole 250b is ejected into the processing chamber 201 from the gas supply hole 250c. In this manner, in this embodiment, the gas is transported via the nozzles 249a and 249b and the buffer chamber 237 disposed in the cylindrical space. In addition, the gas is ejected into the reaction tube 203 only near the wafer 200 from the gas supply holes 250a to 250c. Further, the main flow of the gas in the reaction tube 203 is in a direction parallel to the surface of the wafer 200, i.e., the horizontal direction. The gas flowing on the surface of the wafer 200, i.e., the residual gas after the reaction, flows in the direction of the exhaust port, i.e., the exhaust pipe 231 described later. As a raw material gas containing a predetermined element, for example, a raw material gas containing silicon (Si) and a halogen element as the predetermined element is supplied into the processing chamber 201 from the gas supply pipe 232a via the MFC241a and the valve 243a. A nitrogen-containing (N) gas as a nitriding gas is supplied into the processing chamber 201 from the gas supply pipe 232b via the MFC241b and the valve 243b. As the nitriding gas, a nitrogen-containing gas activated by plasma excitation can be used. In addition, as the nitriding gas, a nitrogen-containing gas activated by thermal excitation without using plasma excitation (i.e., by non-plasma excitation) can also be used. Carbon (C)- and nitrogen (N)-containing gas is supplied from the gas supply pipe 232c into the processing chamber 201 via the MFC 241c and the valve 243c. It should be noted that the C- and N-containing gas can also be regarded as a C-containing gas. Inert gas is supplied from the gas supply pipes 232d and 232e into the processing chamber 201 via the MFCs 241d and 241e and the valves 243d and 243e, respectively. The raw material gas supply system mainly consists of the gas supply pipe 232a, the MFC 241a, and the valve 243a. It is also possible to consider including the nozzle 249a in the raw material gas supply system. The raw material gas supply system can also be referred to as the raw material supply system. In addition, the N-containing gas supply system mainly consists of the gas supply pipe 232b, the MFC 241b, and the valve 243b. It is also possible to consider including the nozzle 249b and the buffer chamber 237 in the N-containing gas supply system. The N-containing gas supply system can also be referred to as the nitriding gas supply system or the nitriding agent supply system. In addition, the C- and N-containing gas supply system mainly consists of the gas supply pipe 232c, the MFC 241c, and the valve 243c. It is also possible to include the downstream side of the connection portion of the gas supply pipe 232b and the gas supply pipe 232c, the nozzle 249b, and the buffer chamber 237 in the C- and N-containing gas supply system. The C- and N-containing gas supply system can also be regarded as a C-containing gas supply system. Any one or all of the above raw material gas, N-containing gas, and C- and N-containing gas can also be referred to as the processing gas. In addition, any one or all of the raw material gas supply system, the N-containing gas supply system, and the C- and N-containing gas supply system can be referred to as the processing gas supply system, or simply as the supply system. In addition, the inert gas supply system mainly consists of the gas supply pipes 232d and 232e, the MFCs 241d and 241e, and the valves 243d and 243e. The inert gas supply system can also be referred to as the purge gas supply system or the carrier gas supply system. In the buffer chamber 237, as shown in FIG. 2, two rod-shaped electrodes 269 and 270 made of a conductor and having an elongated structure are arranged from the lower part to the upper part of the reaction tube 203 along the arrangement direction of the wafers 200. The rod-shaped electrodes 269 and 270 are respectively disposed in parallel with the nozzle 249b. Each of the rod-shaped electrodes 269 and 270 is protected by being covered with an electrode protection tube 275 from the upper part to the lower part. Either one of the rod-shaped electrodes 269 and 270 is connected to a high-frequency power supply 273 via a matcher 272, and the other is connected to a ground wire as a reference potential. By applying high-frequency (RF) power from the high-frequency power supply 273 between the rod-shaped electrodes 269 and 270, plasma is generated in the plasma generation region 224 between the rod-shaped electrodes 269 and 270. The plasma source as a plasma generator (plasma generation section) is mainly composed of the rod-shaped electrodes 269 and 270 and the electrode protection tube 275. It is also conceivable to include the matcher 272 and the high-frequency power supply 273 in the plasma source. As described later, the plasma source functions as a plasma excitation section (activation mechanism) for plasma-exciting the gas, that is, exciting (activating) it into a plasma state. An exhaust pipe 231 for exhausting the atmosphere in the processing chamber 201 is provided on the reaction tube 203. On the exhaust pipe 231, a pressure sensor 245 as a pressure detector (pressure detection section) for detecting the pressure in the processing chamber 201 and an APC (Auto Pressure Controller) valve 244 as a pressure regulator (pressure regulation section) are connected to a vacuum pump 246 as a vacuum exhaust device. The APC valve 244 is a valve configured such that by opening and closing the valve in a state where the vacuum pump 246 is operating, vacuum exhaust and vacuum exhaust stop of the processing chamber 201 can be performed. Further, in a state where the vacuum pump 246 is operating, the valve opening degree is adjusted based on the pressure information detected by the pressure sensor 245, so that the pressure in the processing chamber 201 can be adjusted. The exhaust system is mainly composed of the exhaust pipe 231, the APC valve 244, and the pressure sensor 245. The vacuum pump 246 may also be included in the exhaust system. A sealing cover 219 as a furnace port cover body that can hermetically seal the lower end opening of the reaction tube 203 is provided below the reaction tube 203. On the side of the sealing cover 219 opposite to the processing chamber 201, a rotation mechanism 267 for rotating a susceptor 217 described later is provided. The rotation shaft 255 of the rotation mechanism 267 is connected to the susceptor 217, and is configured to rotate the wafer 200 by rotating the susceptor 217. A susceptor elevator 115 as a lifting mechanism vertically provided outside the reaction tube 203 is configured to be able to carry the susceptor 217 into and out of the processing chamber 201 by lifting the sealing cover 219. The susceptor 217 as a substrate support is configured to support a plurality of wafers 200, for example, 25 to 200 wafers, in a horizontal posture and in a state where their centers are aligned with each other in a multi-layered manner in the vertical direction, that is, they are arranged at intervals. Below the susceptor 217, heat insulating plates 218 are supported in a multi-layered manner in a horizontal posture. A temperature sensor 263 as a temperature detector is provided in the reaction tube 203. By adjusting the energization condition of the heater 207 based on the temperature information detected by the temperature sensor 263, the temperature in the processing chamber 201 is made to be a desired temperature distribution. As shown in FIG. 3, the controller 121 as a control unit (control unit) is configured as a computer including a CPU (Central Processing Unit) 121a, a RAM (Random Access Memory) 121b, a memory device 121c, and an I / O port 121d. The RAM 121b, the memory device 121c, and the I / O port 121d are configured to be able to exchange data with the CPU 121a via an internal bus 121e. An input / output device 122 configured as a touch panel or the like, for example, is connected to the controller 121. In addition, an external memory device 123 can be connected to the controller 121. It should be noted that the substrate processing apparatus can be configured to include one control unit or can be configured to include a plurality of control units. That is, one control unit can be used to control the processing sequence described later, or a plurality of control units can be used to control the processing sequence described later. In addition, the plurality of control units can be configured as a control system connected to each other via a wired or wireless communication network, or the control system as a whole can be used to control the processing sequence described later. When the term "control unit" is used in this specification, in addition to the case including one control unit, there are also cases including a plurality of control units and cases including a control system composed of a plurality of control units. The memory device 121c is constituted by, for example, a flash memory, an HDD (Hard Disk Drive), or the like. A control program for controlling the operation of the substrate processing device, a process recipe that describes steps, conditions, etc. of the substrate processing described later, and the like are stored in the memory device 121c in a readable manner. The process recipe is composed of steps in the substrate processing steps described later executed by the controller 121 and combined in such a way as to obtain a prescribed result, and functions as a program. Hereinafter, the process recipe, the control program, etc. are collectively abbreviated as a program. In addition, the process recipe is also abbreviated as a recipe. In this specification, when the term "program" is used, it may include only the recipe alone, only the control program alone, or both of them. The RAM 121b is configured as a memory area (working area) that temporarily holds programs, data, etc. read by the CPU 121a. The I / O port 121d is connected to the above-described MFCs 241a to 241e, valves 243a to 243e, pressure sensor 245, APC valve 244, vacuum pump 246, heater 207, temperature sensor 263, rotation mechanism 267, susceptor elevator 115, matcher 272, high-frequency power supply 273, and the like. The CPU 121a is configured to read the control program from the memory device 121c and execute it, and read the process recipe from the memory device 121c based on the input of an operation command from the input / output device 122 or the like. The CPU 121a is configured to be able to control the flow rate adjustment operation of various gases based on the MFCs 241a to 241e, the opening and closing operations of the valves 243a to 243e, the opening and closing operation of the APC valve 244, the pressure adjustment operation using the APC valve 244 based on the pressure sensor 245, the start and stop of the vacuum pump 246, the temperature adjustment operation of the heater 207 based on the temperature sensor 263, the rotation and rotation speed adjustment operation of the susceptor 217 based on the rotation mechanism 267, the lifting operation of the susceptor 217 based on the susceptor elevator 115, the impedance adjustment operation based on the matcher 272, the power supply to the high-frequency power supply 273, and so on, according to the content of the read process recipe. The controller 121 can be configured by installing the above program stored in an external memory device (such as magnetic disks like magnetic tapes, floppy disks, hard disks, optical disks like CDs, DVDs, magneto-optical disks like MOs, semiconductor memories like USB memories, memory cards, etc.) 123 into the computer. The memory device 121c and the external memory device 123 are configured as computer-readable recording media. Hereinafter, they are collectively and simply referred to as recording media. When the term "recording medium" is used in this specification, there are cases where only the memory device 121c is included alone, only the external memory device 123 is included alone, or cases where both are included. It should be noted that the program can also be provided to the computer using a communication unit such as the Internet or a dedicated line instead of using the external memory device 123. (2) Substrate processing step Using FIG. 4, as one step of the manufacturing process of a semiconductor device (Device), an example of the sequence of forming a second film on a wafer 200 having a first film as a base using the above substrate processing device will be described. In the following description, the operations of each part constituting the substrate processing device are controlled by the controller 121. The substrate processing sequence shown in FIG. 4 includes: (a) a step of forming an intermediate layer containing carbon (C) and nitrogen (N), or a C-containing intermediate layer without N on the first film formed on the wafer 200 as a substrate (intermediate layer forming step); and (b) a step of forming a second film containing N using an activated N-containing gas on the above intermediate layer (second film forming step). It should be noted that in this specification, the intermediate layer containing C and N and the C-containing intermediate layer without N are sometimes collectively referred to as the C-containing intermediate layer. In this specification, for convenience, the sequence of substrate processing shown in FIG. 4 is sometimes shown as follows. Also, in this specification, for convenience, the N-containing gas activated by plasma excitation is referred to as N-containing gas*. The same notation is also used in the following description of the modification examples. (Raw material gas → C and N-containing gas) × m → (Raw material gas → N-containing gas*) × n ⇒ Second film / Intermediate layer The term "wafer" used in this specification has cases where it refers to the wafer itself, and cases where it refers to the laminate of the wafer and the specified layer and film formed on its surface. The term "surface of the wafer" used in this specification has cases where it refers to the surface of the wafer itself, and cases where it refers to the surface of the specified layer formed on the wafer. When it is described in this specification that "a specified layer is formed on the wafer", there are cases where it refers to directly forming a specified layer on the surface of the wafer itself, and cases where it refers to forming a specified layer on the layer formed on the wafer. The case of using the term "substrate" in this specification is also synonymous with the case of using the term "wafer". (Wafer Filling and Cassette Loading) Multiple wafers 200 are loaded (wafer filling) into a cassette 217. Thereafter, as shown in FIG. 1, the cassette 217 supporting the multiple wafers 200 is lifted by a cassette elevator 115 and carried into the processing chamber 201 (cassette loading). In this state, the sealing lid 219 seals the lower end of the reaction tube 203. An oxide film as a first film is formed in advance on at least a part of the surface of the wafer 200. This film becomes at least a part of the base film when forming the intermediate layer in the intermediate layer forming step described later. The oxide film may be formed so as to cover the entire area of the surface of the wafer 200, or may be formed so as to cover only a part thereof. As the oxide film, for example, a silicon oxide film (SiO film), a silicon oxynitride film (SiON film), a silicon oxycarbide film (SiOC film), a silicon oxycarbonitride film (SiOCN film) and other Si-containing films, an aluminum oxide film (AlO film), a hafnium oxide film (HfO film), a zirconium oxide film (ZrO film), a titanium oxide film (TiO film) and other metal oxide films, that is, a high dielectric constant insulating film (High-k film) can be formed. In the oxide film (or oxynitride film, oxycarbide film, oxycarbonitride film) described here, for example, in addition to the oxide film intentionally formed by performing a predetermined process such as CVD process, plasma CVD process, thermal oxidation process, plasma oxidation process, etc., it sometimes includes a natural oxide film naturally formed due to the wafer 200 being exposed to the atmosphere during the conveyance of the wafer 200 or the like. However, the first film is not limited to the oxide film, and may be other films in cases where a transition layer is formed between the first film and the second film described later. In addition, the first film is not limited to the film formed on the surface of the wafer 200, and sometimes the surface of the wafer 200 itself constitutes the first film as the base film. (Pressure Regulation and Temperature Regulation) Vacuum exhaust (pressure reduction exhaust) is performed using a vacuum pump 246 so that the pressure in the processing chamber 201, that is, the pressure in the space where the wafer 200 is present, becomes a desired pressure (vacuum degree). At this time, the pressure in the processing chamber 201 is measured by a pressure sensor 245, and feedback control is performed on the APC valve 244 based on the measured pressure information. The vacuum pump 246 maintains an operating state throughout at least until the processing of the wafer 200 is completed. In addition, heating is performed using a heater 207 so that the wafer 200 in the processing chamber 201 becomes a desired temperature. In addition, rotation of the cassette 217 and the wafer 200 based on a rotation mechanism 267 is started. Rotation of the cassette 217 and the wafer 200 based on the rotation mechanism 267 continues at least until the processing of the wafer 200 is completed. (Intermediate Layer Forming Step) Then, the following two steps, that is, step S1a and step S1b, are executed. [Step S1a] In this step, a source gas is supplied to the wafer 200 in the processing chamber 201. Specifically, valve 243a is opened, and the source gas flows into the gas supply pipe 232a. The source gas is flow-regulated by MFC241a, supplied into the processing chamber 201 via the nozzle 249a, and exhausted from the exhaust pipe 231. At this time, the source gas is supplied to the wafer 200. At this time, valve 243d is opened simultaneously to allow the inert gas to flow into the gas supply pipe 232d. The inert gas is flow-regulated by MFC241d, supplied into the processing chamber 201 together with the source gas, and exhausted from the exhaust pipe 231. That is, in this step, the source gas is supplied to the central region within the substrate surface, and the inert gas and the source gas are supplied together to the central region of the wafer 200. As the processing conditions when supplying the source gas in this step, the following can be exemplified: Processing temperature: 250 to 700 °C, preferably 300 to 650 °C, more preferably 350 to 600 °C; Processing pressure: 1 to 2666 Pa, preferably 67 to 1333 Pa; Source gas supply flow rate: 1 to 2000 sccm, preferably 10 to 1000 sccm; Source gas supply time: 1 to 120 seconds, preferably 1 to 60 seconds; Inert gas supply flow rate (for each nozzle): 100 to 10000 sccm. It should be noted that, from the perspective of improving the processing speed, it is particularly preferred that the processing temperature be substantially the same temperature in any step of the intermediate layer formation step. It should be noted that the expression of the numerical range such as "250 to 700 °C" in the present invention means that the lower limit value and the upper limit value are included in this range. Therefore, for example, "250 to 700 °C" means "250 °C or higher and 700 °C or lower". The same applies to other numerical ranges. The processing temperature in the present invention refers to the temperature of the wafer 200 or the temperature within the processing chamber 201, and the processing pressure refers to the pressure within the processing chamber 201. In addition, the processing time refers to the duration of this processing. The same applies in the following description. By supplying the source gas to the wafer 200 under the above conditions, a first layer containing a specified element with a thickness of, for example, less than 1 atomic layer to several atomic layers is formed on the wafer 200 (including the base film of the first film on the surface). For example, when using a gas containing Si and Cl as the source gas, a Si-containing layer containing Cl is formed as the first layer. It should be noted that in the first layer, sometimes the O contained in the first film as the base may be captured into the first layer. In this specification, for convenience, the first layer containing Cl and O (Si-containing layer containing O and Cl) may sometimes be simply referred to as the Si-containing layer. After forming the first layer, valve 243a is closed to stop the supply of the source gas. At this time, with the APC valve 244 kept open, the processing chamber 201 is evacuated by the vacuum pump 246 to remove the unreacted source gas remaining in the processing chamber 201 or the source gas that has contributed to the formation of the first layer from the processing chamber 201. At this time, with valves 243d and 243e kept open, the supply of the inert gas to the processing chamber 201 is maintained. The inert gas functions as a purge gas. Examples of the source gas include hexachlorodisilane (Si 2 Cl 6 ) gas, monochlorosilane (SiH 3 Cl) gas, dichlorosilane (SiH 2 Cl 2 ) gas, trichlorosilane (SiHCl 3 ) gas, tetrachlorosilane (SiCl 4 ) gas, octachlorotrisilane (Si 3 Cl 8 ) gas and other inorganic halogenated silane source gases. In addition, as the source gas, ethylenebis(trichlorosilane) gas, i.e., 1,2-bis(trichlorosilyl)ethane ((SiCl 3 ) 2 C 2 H 4 ) gas, bis(trichlorosilyl)methane ((SiCl 3 ) 2 CH 2 ) gas and other alkylenebis(halosilane) source gases can also be used. In addition, as the source gas, 1,1,2,2-tetrachloro-1,2-dimethyldisilane ((CH 3 ) 2 Si 2 Cl 4 ) Gas, 1,2-dichloro-1,1,2,2-tetramethyldisilane ((CH 3 ) 4 Si 2 Cl 2 ) Gas, 1-chloro-1,1,2,2,2-pentamethyldisilane ((CH 3 ) 5 Si 2 Cl) gas and other alkyl halide silane raw material gases. In addition, as the raw material gas, silane (SiH 4 ) gas, disilane (Si 2 H 6 ) gas, trisilane (Si 3 H 8 ) gas and other inorganic raw material gases can be used. In addition, as the raw material gas, for example, tetrakis(dimethylamino)silane (Si[N(CH 3 ) 2 4 ) gas, tris(dimethylamino)silane (Si[N(CH 3 ) 2 3 H) gas, bis(diethylamino)silane (Si[N(C 2 H 5 ) 2 2 H 2 ) gas, bis(tert-butylamino)silane (SiH 2 [NH(C 4 H 9)] 2 )Amino-silane raw material gas such as gas. As the raw material gas, one or more of the above gases can be used. As the inert gas, for example, in addition to nitrogen (N 2 ) gas, noble gases such as argon (Ar) gas, helium (He) gas, neon (Ne) gas, and xenon (Xe) gas can also be used. As the inert gas, one or more of them can be used. The same applies to the following description of the inert gas. [Step S1b] After the end of Step S1a, a C- and N-containing gas is supplied to the wafer 200 in the processing chamber 201, that is, the first layer formed on the first film 300. Specifically, the valve 243c is opened to allow the C- and N-containing gas to flow into the gas supply pipe 232c. The C- and N-containing gas is flow-regulated by the MFC241c and supplied into the processing chamber 201 via the gas supply pipe 232b, the nozzle 249b, and the buffer chamber 237, and exhausted from the exhaust pipe 231. At this time, the C- and N-containing gas is supplied to the wafer 200. At the same time, the valve 243e is opened to allow the inert gas to flow into the gas supply pipe 232e. The inert gas is flow-regulated by the MFC241e and supplied into the processing chamber 201 together with the C- and N-containing gas. That is, in this step, the C- and N-containing gas is supplied to the central region in the plane of the substrate, and the inert gas and the C- and N-containing gas are supplied together to the central region of the wafer 200. In this step, as the processing conditions when supplying the C- and N-containing gas, the following can be exemplified: Processing pressure: 1 to 5000 Pa, preferably 1 to 4000 Pa; C- and N-containing gas supply flow rate: 100 to 10000 sccm; C- and N-containing gas supply time: 1 to 200 seconds, preferably 1 to 120 seconds, more preferably 1 to 60 seconds. Other processing conditions can be set to be the same as the processing conditions when supplying the raw material gas. By supplying a C- and N-containing gas to the wafer 200 under the above conditions, the first layer formed on the wafer 200 in step S1a can react with the C- and N-containing gas. Specifically, for example, the halogen element (halogen group) contained in the first layer, i.e., Cl (chlorine group), can react with the C-containing ligand contained in the C- and N-containing gas. Thus, at least a part of Cl in the Cl contained in the first layer is extracted (separated) from the first layer, and at least a part of the C-containing ligand contained in the C- and N-containing gas is separated from the C- and N-containing gas. The C-containing ligand is, for example, an alkyl group such as ethyl or methyl composed of C and hydrogen (H). And, N of the C- and N-containing gas after at least a part of the C-containing ligand is separated can bond to the Si contained in the first layer to form an Si-N bond. In addition, at this time, C contained in the C-containing ligand separated from the C- and N-containing gas can also bond to the Si contained in the first layer to form an Si-C bond. As a result, Cl is detached from the first layer, and at the same time, the N component is newly captured into the first layer. In addition, at this time, the C component is also newly captured into the first layer. By supplying the C- and N-containing gas under the above conditions, the first layer can react appropriately with the C- and N-containing gas, making it possible for the above series of reactions to occur. In addition, by this series of reactions, the N component and the C component are newly captured into the first layer, and the first layer is transformed (modified) into a layer containing a specified element, and C and N. Specifically, for example, it is transformed into a silicon carbonitride layer (SiCN layer) as the second layer. This layer may also be referred to as a C-containing SiN layer. The second layer becomes a layer with a thickness of less than 1 atomic layer to about several atomic layers. In addition, the second layer becomes a layer with a relatively large proportion of Si component and C component, that is, a layer rich in Si and rich in C. After forming the second layer, the valve 243c is closed, and the supply of the C- and N-containing gas is stopped. In addition, by the same processing steps as in step S1a, the unreacted C- and N-containing gas and reaction by-products remaining in the processing chamber 201 after contributing to the formation of the second layer are exhausted from the processing chamber 201. As the C- and N-containing gas, for example, an organic hydrazine-based gas, an amine-based gas, etc. can be used. As the organic hydrazine-based gas, monomethylhydrazine ((CH 3 )HN 2 H 2 ) gas, dimethylhydrazine ((CH 3 ) 2 N 2 H 2 ) gas, trimethylhydrazine ((CH 3 ) 2 N 2 (CH 3 )H) gas such as methylhydrazine-based gas. In addition, as the organic hydrazine-based gas, ethylhydrazine ((C 2 H 5 )HN 2 H 2 ) gas such as ethylhydrazine-based gas. As the amine-based gas, for example, triethylamine ((C 2 H 5 ) 3 N) gas, diethylamine ((C 2 H 5 ) 2 NH) gas, monoethylamine (C 2 H 5 NH 2 ) gas such as ethylamine-based gas. In addition, as the amine-based gas, trimethylamine ((CH 3 ) 3 N) gas, dimethylamine ((CH 3 ) 2 NH) gas, monomethylamine (CH 3 NH 2 ) gas such as methylamine-based gas. In addition, as the amine-based gas, tripropylamine ((C 3 H 7 ) 3 N) gas, dipropylamine ((C 3 H 7 ) 2 NH) gas, monopropylamine (C 3 H 7 NH 2 ) gas and other propylamine-based gases. In addition, as amine-based gases, triisopropylamine ([(CH 3 ) 2 CH] 3 N) gas, diisopropylamine ([(CH 3 ) 2 CH] 2 NH) gas, monoisopropylamine ((CH 3 ) 2 CHNH 2 ) gas and other isopropylamine-based gases. In addition, as amine-based gases, tributylamine ((C 4 H 9 ) 3 N) gas, dibutylamine ((C 4 H 9 ) 2 NH) gas, monobutylamine (C 4 H 9 NH 2 ) gas and other butylamine-based gases. In addition, as amine-based gases, triisobutylamine ([(CH 3 ) 2 CHCH 2 3 N) gas, diisobutylamine ([(CH 3 ) 2 CHCH 2 2 NH) gas, mono-isobutylamine ((CH 3 ) 2 CHCH 2 NH 2 ) gas and other isobutylamine-based gases. That is, as the amine-based gas, for example, (C 2 H 5 ) x NH 3-x 、(CH 3 ) x NH 3-x ,(C 3 H 7 ) x NH 3-x 、[(CH 3 ) 2 CH] x NH 3-x 、(C 4 H 9 ) x NH 3-x 、[(CH 3 ) 2 CHCH 2 x NH 3-x (where x is an integer from 1 to 3) and one or more of the gases. As the C- and N-containing gas, one or more of the above gases can be used. (Number of implementation regulations) By performing the cycle of steps S1a and S1b non-simultaneously, i.e., asynchronously, m or more times (m is an integer of 1 or 2 or more), thereby, as shown in (A) of FIG. 5, on the first film 300 formed on the wafer 200, an intermediate layer 400 containing a specified element, C, and N can be formed. That is, the intermediate layer 400 contains a specified element other than C and N. As the intermediate layer 400, for example, a SiCN layer containing Si, C, and N as the specified element can be formed. The intermediate layer 400 can also be referred to as a seed layer. It should be noted that in step S1b, a C-containing gas without N can be used instead of the C- and N-containing gas, thereby forming a C-containing layer without N (e.g., a SiC layer) as the intermediate layer 400. Here, in order to explain the effect of forming the intermediate layer 400 between the first film 300 and the second film 600, first, the case of directly forming the nitride film as the second film 600 on the oxide film as the first film 300 will be explained. When the second film 600 is directly formed on the first film 300, sometimes oxygen (O), which is an element contained in the first film 300, diffuses into the second film 600 that is substantially free of O. Due to this diffusion of O, a layer (O diffusion layer) containing O in addition to the specified element and N is formed at the interface between the second film 600 and the first film 300. Since the O diffusion layer contains O, the etching rate is different (i.e., the etching resistance is different) with respect to the second film 600. In other words, in the vicinity of the interface between the second film 600 and the first film 300, in the thickness direction from the second film 600 toward the first film 300, a transition layer is formed in which the magnitude of the etching rate transitions (changes) according to the diffusion concentration of O and the like. The transition layer has a gradient of O concentration such that the closer to the first film 300, the greater the O concentration, and the farther from the first film 300, the smaller the O concentration. The etching rate of the transition layer also transitions according to the gradient of the O concentration. More specifically, for example, when using an etchant (e.g., hydrogen fluoride (HF) gas, diluted HF aqueous solution, etc.) that has a high etching rate with respect to the oxide film as the first film 300 and a low etching rate with respect to the nitride film as the second film 600, in the thickness direction toward the first film 300, a layer that transitions in a manner that the etching rate gradually increases is formed in a part of the second film 600. Regarding the above-mentioned transition layer, for example, when it is desired to selectively remove only the first film 300 by etching treatment with respect to the second film 600, sometimes not only the first film 300 that is the etching target but also at least a part of the transition layer with a high etching rate (low etching resistance) compared to the second film 600 is etched, reducing the controllability of the etching. Therefore, when forming the second film 600, sometimes it is required to suppress the formation of such a transition layer or reduce the thickness of the formed transition layer. In the technology of the present invention, an intermediate layer 400 containing C is pre-formed on the first film 300. When the second film 600 is formed on the intermediate layer 400, at least a part of C contained in the intermediate layer 400 diffuses to the vicinity of the interface of the second film 600. Specifically, as shown in (B) of FIG. 5, a diffusion layer 500 containing C is formed by the diffusion of C into the second film 600 when the second film 600 is formed in the vicinity of the interface between the intermediate layer 400 and the second film 600. The diffusion layer 500 has a gradient of C concentration such that the C concentration is higher closer to the first film 300 and lower farther away from the first film 300. Here, the C element contained in the intermediate layer 400 functions in such a way as to reduce the etching rate (increase the corrosion resistance) of the part of the second film 600 where C has diffused. Therefore, C in the diffusion layer 500 functions in such a way that the etching rate is significantly reduced closer to the first film 300 and slightly reduced farther away from the first film 300. Here, as described above, for the increase in the etching rate caused by O diffusing from the first film 300, corresponding to the gradient of the O concentration, it tends to be larger closer to the first film 300 and smaller farther away from the first film 300. Therefore, when the second film 600 is formed, by forming a diffusion layer 500 having the same gradient of C concentration as the O concentration, the formation of the transition layer caused by the diffusion of O can be suppressed, and in addition, the thickness of the formed transition layer can be reduced. In (B) of FIG. 5, the transition layer whose thickness is reduced by forming the diffusion layer 500 is denoted as the transition layer 700. The thickness of the transition layer 700 varies according to the C concentration distribution, O concentration distribution, etc. in the diffusion layer 500 (in the thickness direction). For example, as described later, by adjusting the C content per unit area of the intermediate layer 400, the thickness of the transition layer 700 can be reduced or its thickness can be substantially eliminated (made zero). It should be noted that the transition layer 700 can also be said to be a layer in which the etching rate has changed due to the diffusion of O into the second film 600 and whose etching rate is different from both the first film 300 and the second film 600. In addition, the intermediate layer 400 containing C also functions as a barrier layer (diffusion barrier layer) for suppressing the diffusion of O from the first film 300 of the substrate to the second film 600 in the second film forming step. Thereby, the effect of further reducing the thickness of the transition layer 700 can be obtained. Furthermore, in the second film formation step described later, the nitrogen-containing gas is plasma-excited to be activated, and the activated nitrogen-containing gas is used to form the second film 600 as a nitrogen-containing film. At this time, since radicals and the like contained in the activated nitrogen-containing gas have too high reactivity, at least a part of the C contained in the intermediate layer 400 may be detached from the intermediate layer 400 by these radicals and the like and may not diffuse into the second film 600. In addition, at this time, the activated nitrogen-containing gas is supplied from the outer edge (i.e., the outer region) of the wafer 200 toward the central region. Therefore, more C is detached from the intermediate layer 400 in the outer region than in the central region in the plane of the substrate. That is, the amount of C detached per unit area from the intermediate layer 400 is different between the central region and the outer region in the plane of the substrate, and the amount of C diffusing into the second film 600 per unit area is smaller in the outer region than in the central region in the plane of the substrate. More specifically, in the outer region and the central region, at least one of the thickness of the diffusion layer 500 and the C content (C concentration) per unit area in the diffusion layer 500 is different. For example, in this case, the thickness of the diffusion layer 500 is smaller in the outer region and larger in the inner region. In addition, in this case, the C content (C concentration) in the diffusion layer 500 is smaller in the outer region and larger in the central region. Furthermore, in the central region and the outer region in the plane of the substrate, at least one of the thickness of the diffusion layer 500 and the C content (C concentration) per unit area in the diffusion layer 500 is different. Thus, in the central region and the outer region in the plane of the substrate, the thickness of the transition layer 700 with different etching rates will be different. More specifically, depending on at least one of the thickness of the diffusion layer 500 and the C content (C concentration) per unit area in the diffusion layer 500, the thickness of the transition layer 700 in the outer region becomes larger than the thickness of the transition layer 700 in the central region. Thus, if the thickness of the transition layer 700 in the plane of the substrate becomes non-uniform, then in the etching process of the first film 300, at least a part of the transition layer 700 is etched together with the first film 300. Thus, the thickness of the remaining second film 600 in the plane of the substrate may sometimes become non-uniform. Therefore, it is desirable that the thickness of the transition layer 700 be as thin as possible and uniform in the plane of the substrate. Therefore, in the technology of the present invention, in the above-described intermediate layer forming step, the intermediate layer 400 is formed in such a manner that the amount of C per unit area contained in the intermediate layer 400 is different between the central region and the outer region within the substrate surface. For example, the intermediate layer 400 is formed in such a manner that the amount of C per unit area contained in the intermediate layer 400 is different between the center and the outer edge (outer periphery) within the substrate surface. Specifically, the intermediate layer 400 is formed in such a manner that the C content per unit area contained in the intermediate layer 400 becomes larger in the outer region than in the central region. By forming the intermediate layer 400 in this way, in the second film forming step, even when C in the intermediate layer 400 in the outer region of the wafer 200 is more likely to be detached than C in the intermediate layer 400 in the central region of the wafer 200, in the second film forming step, the amount of C per unit area diffused into the second film 600 (i.e., the C content of the diffusion layer 500 per unit area) can be made to have a desired distribution within the substrate surface. In addition, thereby, the in-plane distribution of the thickness of the transition layer 700 can be made to have a desired distribution, such as a uniform distribution. That is, by adjusting the in-plane distribution of the C content of the intermediate layer 400, the deviation of the thickness distribution of the transition layer 700 can be reduced, and adjustment can be made to make it closer to uniform or the like. Regarding the adjustment of the distribution of the C content per unit area contained in the intermediate layer 400, in the above-described intermediate layer forming step, for example, it is performed by adjusting the thickness of the intermediate layer 400 within the substrate surface or the C concentration contained in the intermediate layer 400. For example, in this step, the intermediate layer 400 is formed in such a manner that the thickness of the intermediate layer 400 is different between the central region and the outer region within the substrate surface. Specifically, the intermediate layer 400 is formed in such a manner that the thickness of the intermediate layer 400 becomes larger in the outer region than in the central region within the substrate surface. By adjusting the thickness of the intermediate layer 400, the distribution of the C content per unit area within the substrate surface can be controlled. More specifically, in the above step S1a, the pressure of the processing space (i.e., the processing chamber 201) in which the wafer 200 is to be processed is set to be larger than the pressure at which the thickness of the intermediate layer 400 becomes uniform within the substrate surface. By increasing the pressure of the processing space, the mean free path in the processing space is reduced, and the raw material gas is promoted to be adsorbed in the outer region within the substrate surface. By adsorbing more raw material gas in the outer region within the substrate surface than in the central region, adjustment can be made in such a manner that the thickness of the intermediate layer 400 in the outer region within the substrate surface becomes larger than the thickness of the intermediate layer 400 in the central region. That is, the thickness of the intermediate layer 400 can be adjusted to have a concave distribution within the substrate surface. In addition, in the above step S1a, the time for supplying the source gas is set to be shorter than the time for the thickness of the intermediate layer 400 to become uniform in the plane of the substrate. By shortening the supply time of the source gas, the amount of the source gas reaching the central region of the wafer 200 is reduced. As a result, it is possible to adjust the thickness of the intermediate layer 400 in the outer and inner regions of the substrate plane to be larger than the thickness of the intermediate layer 400 in the central region. That is, it is possible to adjust the thickness of the intermediate layer 400 to be concave in the plane of the substrate. In addition, in the above step S1a, the flow rate of the inert gas supplied simultaneously with the source gas from the nozzle 249a and the flow rate of the inert gas supplied from the nozzle 249b are set to be larger than the flow rate of the inert gas for the thickness of the intermediate layer 400 to become uniform in the plane of the substrate. By increasing the flow rate of the inert gas supplied to the central region of the wafer 200, the partial pressure of the source gas supplied to the central region is reduced, and relatively, the partial pressure of the source gas supplied to the outer region is increased. Thereby, it is possible to adjust the thickness of the intermediate layer 400 in the outer and inner regions of the substrate plane to be larger than the thickness of the intermediate layer 400 in the central region. That is, it is possible to adjust the thickness of the intermediate layer 400 to be concave in the plane of the substrate. The average thickness of the intermediate layer 400 in the plane of the substrate is, for example, 7 to 35 Å, preferably in the range of 23 to 30 Å. If the average thickness of the intermediate layer 400 in the plane of the substrate is less than 7 Å, it may be difficult to obtain the effect of reducing the thickness of the transition layer 700 formed in the second film formation step. By setting the average thickness of the intermediate layer 400 in the plane of the substrate to be 7 Å or more, the effect of reducing the thickness of the transition layer 700 can be obtained. By making the average thickness of the intermediate layer 400 in the plane of the substrate 23 Å or more, the effect of reducing the thickness of the transition layer 700 can be obtained more reliably. If the average thickness of the intermediate layer 400 in the plane of the substrate exceeds 35 Å, the amount of C diffused per unit area into the second film 600 becomes excessive, and it may be difficult to obtain desired characteristics such as electrical characteristics for the second film 600. By making the average thickness of the intermediate layer 400 in the plane of the substrate 35 Å or less, it is easy to obtain the desired characteristics for the second film 600. By making the average thickness of the intermediate layer 400 in the plane of the substrate 30 Å or less, it is easier to obtain the desired characteristics for the second film 600. In addition, the difference (also referred to as deviation) in thickness between the central region and the outer region of the intermediate layer 400 in the plane of the substrate, that is, between the center and the outer periphery (outer edge) in the plane of the substrate, is set to, for example, 4 to 10 Å, preferably 5 to 8 Å. The magnitude of this deviation can be selected according to the magnitude of the deviation in the amount of C detached from the intermediate layer 400 in the plane of the substrate in the second film formation step. As described above, when adjusting in such a manner that the thickness of the intermediate layer 400 in the outer region becomes larger than the thickness of the intermediate layer 400 in the central region within the substrate surface in step S1a, it is preferable to make the thickness of the second film 600 formed in the second film formation step described later larger in the central region than in the outer region within the plane of the wafer 200. Thereby, the total film thickness of the film formed by laminating the intermediate layer 400 and the second film 600 can be made closer to uniform within the plane of the wafer 200. In addition, for example, in this step, the intermediate layer 400 is formed in such a manner that the C concentration contained in the intermediate layer 400 is different in the central region and the outer region within the substrate surface. That is, the intermediate layer 400 is formed in such a manner that the C concentration contained in the intermediate layer 400 is larger in the outer region than in the central region within the substrate surface. By adjusting the C concentration contained in the intermediate layer 400, the distribution of the C content per unit area within the substrate surface can be controlled. Specifically, in the above step S1b, the pressure of the processing space where the wafer 200 is processed is made larger than the pressure at which the thickness of the C concentration contained in the intermediate layer 400 becomes uniform within the substrate surface. By adjusting the pressure of the processing space during the supply of the C- and N-containing gas to increase the pressure of the processing space, the mean free path in the processing space is thereby reduced, and the adsorption of the C- and N-containing gas to the outer region within the substrate surface is promoted. As a result, it can be adjusted in such a manner that the C concentration in the intermediate layer 400 in the outer region is larger than the C concentration in the intermediate layer 400 in the central region. In addition, in the above step S1b, the supply time of the C- and N-containing gas is made shorter than the time at which the C concentration contained in the intermediate layer 400 becomes uniform within the substrate surface. By adjusting the supply time of the C- and N-containing gas to shorten the supply time of the C- and N-containing gas, the amount of the C- and N-containing gas reaching the central region of the wafer 200 is thereby reduced. As a result, it can be adjusted in such a manner that the C concentration in the intermediate layer 400 in the outer region is larger than the C concentration in the intermediate layer 400 in the central region. In addition, in the above step S1b, the flow rates of the inert gas supplied simultaneously with the C- and N-containing gas from the nozzle 249b and the inert gas supplied from the nozzle 249a are made larger than the flow rate of the inert gas at which the C concentration contained in the intermediate layer 400 becomes uniform within the substrate surface. By increasing the flow rate of the inert gas supplied to the central region, the partial pressure of the C- and N-containing gas supplied to the central region is thereby reduced, and relatively, the partial pressure of the C- and N-containing gas supplied to the outer region is increased. Thereby, it can be adjusted in such a manner that the C concentration of the intermediate layer in the outer region within the substrate surface is larger than the C concentration in the intermediate layer 400 in the central region. The average concentration of the C concentration within the substrate surface of the intermediate layer 400 is, for example, set to 3 to 15%, preferably set to 5 to 7%. If the average concentration of C in the substrate plane of the intermediate layer 400 is less than 3%, it may be difficult to obtain the effect of reducing the thickness of the transition layer 700 formed in the second film formation step. By setting the average concentration of C in the substrate plane of the intermediate layer 400 to 3% or more, the effect of reducing the thickness of the transition layer 700 can be obtained. By making the average concentration of C in the substrate plane of the intermediate layer 400 5% or more, the effect of reducing the thickness of the transition layer 700 can be obtained more reliably. If the average concentration of C in the substrate plane of the intermediate layer 400 exceeds 15%, the C content per unit area of the intermediate layer 400 becomes excessive, and it may be difficult to obtain desired characteristics such as electrical characteristics for the second film 600. By making the average concentration of C in the substrate plane of the intermediate layer 400 15% or less, it is easy to obtain the desired characteristics for the second film 600. By making the average concentration of C in the substrate plane of the intermediate layer 400 7% or less, the desired characteristics can be obtained more easily. In addition, the concentration difference (also referred to as deviation) between the central region and the outer region in the substrate plane of the intermediate layer 400, that is, the center and the outer periphery (outer edge) in the substrate plane, is, for example, 0.3 to 2.2%, preferably 0.7 to 1.8%. The magnitude of this deviation can be selected according to the magnitude of the deviation of the amount of C detached from the intermediate layer 400 in the substrate plane in the second film formation step. In addition, by adjusting the distribution of the C concentration contained in the intermediate layer 400 while making the distribution of the thickness of the intermediate layer 400 in the substrate plane direction uniform, it is easy to make the thickness of the film formed by laminating the intermediate layer 400 and the second film 600 approach uniformity in the plane of the wafer 200. After performing the intermediate layer formation step, a second film formation step of forming a nitrogen-containing layer without C by using a nitrogen-containing gas excited by plasma is performed. In the present embodiment, the step of forming a nitrogen-containing layer without C (that is, a nitrogen-containing layer without C) on the intermediate layer 400 without using plasma excitation is not performed. In other words, during the period from after performing the intermediate layer formation step to the start of the second film formation step, the step of forming a nitrogen-containing layer without C on the intermediate layer 400 without using plasma excitation is not performed. Thus, by omitting the step of forming a nitrogen-containing layer without C without using plasma excitation, the productivity can be improved. In addition, when forming the N-containing layer without using plasma excitation in the second film formation step, it may be necessary to perform substrate processing at a processing temperature higher than both the intermediate layer formation step and the second film formation step. That is, in order to form the N-containing layer using the thermally excited N-containing gas, the process of forming the N-containing layer is sometimes performed at a temperature higher than that in the case of forming the N-containing layer using plasma excitation. By not performing such a process of forming the N-containing layer using thermal excitation, it is possible to suppress the degradation of the device characteristics due to the thermal history. In addition, by not performing such a process of forming the N-containing layer using thermal excitation, during the period from the start of the intermediate layer formation step to the end of the second film formation step, the temperature of the wafer 200 can be maintained at a temperature not exceeding at least either the temperature of the wafer 200 in the intermediate layer formation step or the temperature of the wafer 200 in the second film formation step. In this step, after performing the next second film formation step, the distribution of the C content per unit area contained in the intermediate layer 400 is set so as to be a prescribed distribution, for example, a uniform distribution, within the substrate surface in terms of the thickness of the transition layer 700. (Second film formation step) After the formation of the intermediate layer 400 is completed, the next two steps, namely steps S2a and S2b, are performed. That is, an N-containing second film 600 is formed on the intermediate layer 400 using an N-containing gas activated by plasma excitation. [Step S2a] In this step, a source gas is supplied to the wafer 200 in the processing chamber 201, that is, the intermediate layer 400 formed on the first film 300. The processing steps of this step are set to be the same as those of step S1a. As the processing conditions when supplying the source gas in this step, examples include: processing temperature: room temperature (25 °C) to 550 °C, preferably 400 to 500 °C. Other processing conditions can be set to be the same as those when supplying the source gas in step S1a. It should be noted that in order to increase the deposition rate per film formation cycle of the second film 600, at least either the supply flow rate or the supply time of, for example, the source gas in the processing conditions of step S2a can be made greater than that in step S1a. By performing step S2a, an Si-containing layer is formed as the third layer on the intermediate layer 400. [Step S2b] After step S2a is completed, an N-containing gas activated by plasma excitation is supplied to the wafer 200 in the processing chamber 201, that is, the third layer formed on the intermediate layer 400. Specifically, valve 243b is opened, and N-containing gas flows into gas supply pipe 232b. The N-containing gas is flow-regulated by MFC241b, supplied into processing chamber 201 through gas supply pipe 232b, nozzle 249b, and is plasma-excited in buffer chamber 237, and exhausted from exhaust pipe 231. At this time, the N-containing gas activated by plasma excitation is supplied to wafer 200. At the same time, valve 243e is opened, and inert gas flows into gas supply pipe 232e. The inert gas is flow-regulated by MFC241e and supplied into processing chamber 201 together with the N-containing gas. As the processing conditions when supplying the N-containing gas in this step, the following can be exemplified: Processing pressure: 1 to 100 Pa; N-containing gas supply flow rate: 100 to 10,000 sccm; N-containing gas supply time (irradiation time): 1 to 120 seconds, preferably 1 to 60 seconds; High-frequency power: 50 to 1000 W. Other processing conditions can be set the same as those for supplying the raw material gas in step S2a. It should be noted that it is preferable that the processing temperature in this step is lower than the processing temperature in step S2c in the following modification example. By supplying the N-containing gas activated by plasma excitation to wafer 200 under the above conditions, compared with the case of using only the N-containing gas activated by thermal excitation, the formation rate of the second film 600 can be increased and the productivity can be improved. In addition, it is sometimes easy to improve the film quality of the second film 600 and suppress the processing temperature, etc. By supplying the activated N-containing gas to wafer 200 under the above conditions, at least a part of the third layer is nitrided (modified). By modifying the third layer, a fourth layer, that is, a layer containing a specified element and N and substantially free of O and C (i.e., an N-containing layer without O and C), is formed on wafer 200, that is, on intermediate layer 400. When forming the fourth layer, impurities such as Cl contained in the third layer form at least a gaseous substance containing Cl, etc. during the modification reaction using the N-containing gas and are exhausted from processing chamber 201. After forming the fourth layer, valve 243b is closed, and the supply of the N-containing gas is stopped. Then, by the same processing steps as in step S1a, the unreacted N-containing gas and reaction by-products remaining in processing chamber 201 after contributing to the formation of the fourth layer are removed from processing chamber 201. As the N-containing gas, ammonia (NH 3 ) gas, diazene (N 2 H 2 ) gas, hydrazine (N 2 H 4 ) gas, N 3 H 8 Hydrogen-based gases such as hydrogen and the like. As the N-containing gas, one or more of them can be used. (Number of implementation regulations) By performing the cycle of the above steps S2a and S2b non-simultaneously, that is, asynchronously, n times (n is an integer of 1 or more), a second film 600 containing a specified element and N can be formed on the intermediate layer 400. As the second film 600, for example, a SiN film containing Si and N as the specified element can be formed. The second film 600 is a film with higher corrosion resistance and lower etching rate compared to the first film 300. In addition, the thickness of the second film 600 is greater than the thickness of the intermediate layer 400. By making the thickness of the second film 600 greater than the thickness of the intermediate layer 400, a second film 600 without a diffusion layer 500 and without C can be formed even after the second film formation step. The thickness of the second film 600 can be, for example, 15 to 500 Å, preferably 20 to 200 Å, and more preferably 30 to 100 Å. It should be noted that, as shown in (B) of FIG. 5, in the second film formation step, a part of the second film 600 containing the diffused C forms a diffusion layer 500 containing C with the intermediate layer 400 due to the diffusion of the C element contained in the intermediate layer 400 into the second film 600. In this step, at least a part of the C contained in the intermediate layer 400 is removed in such a way that the distribution of the C content per unit area contained in the diffusion layer 500 after this step is close to uniform within the substrate surface. Through the above operations, in the second film formation step, at least a part of the C contained in the intermediate layer 400 is removed in such a way that the thickness of the transition layer 700 becomes a specified distribution, for example, close to uniform within the substrate surface. That is, in the intermediate layer formation step, the intermediate layer 400 is formed in such a way that the C content per unit area contained in the intermediate layer 400 is larger in the outer region than in the central region. In the second film formation step, C is removed from the intermediate layer 400 in such a way that the amount of C removed per unit area from the intermediate layer 400 is larger in the outer region than in the central region. At this time, corresponding to the difference between the amount of C removed per unit area from the intermediate layer 400 in the central region within the substrate surface and the amount of C removed per unit area from the intermediate layer 400 in the outer region within the substrate surface, the distribution of the C content per unit area contained in the intermediate layer 400 formed in the intermediate layer formation step is set. Thereby, it is possible to make the C content per unit area contained in the diffusion layer 500 after the second film formation step close to uniform within the substrate surface and make the thickness of the transition layer 700 close to uniform within the substrate surface. (Purge step, atmospheric pressure recovery step) After the formation of the second film 600 is completed, an inert gas is supplied into the processing chamber 201 from the gas supply pipes 232d and 232e, respectively, and exhaust is performed from the exhaust pipe 231. The inert gas functions as a purge gas. Thus, the inside of the processing chamber 201 is purged, and the gas and reaction by-products remaining in the processing chamber 201 are removed (purged) from the processing chamber 201. Then, the atmosphere inside the processing chamber 201 is replaced with an inert gas, and the pressure inside the processing chamber 201 is restored to normal pressure. (Unloading step) Then, the processed wafer 200 is unloaded (wafer boat unloading) from the lower end of the reaction tube 203 to the outside of the reaction tube 203 in a state of being supported on the wafer boat 217 by the wafer boat elevator 115. After the processed wafer 200 is unloaded to the outside of the reaction tube 203, it is taken out from the wafer boat 217 (wafer taking out). (3) Etching process After the wafer 200 is unloaded from the inside of the processing chamber 201, the wafer 200 after substrate processing is further subjected to a film forming process, a resist pattern forming process, etc. Then, the wafer 200 subjected to these processes is loaded into the reaction vessel provided in the etching apparatus. Then, an etchant is supplied to the wafer 200 in the reaction tube in a state of being controlled so as to be at a prescribed processing pressure and processing temperature, whereby the first film 300 etc. formed on the surface of the wafer 200 are etched. As the etchant, an etching gas can be used. As the etching gas, for example, hydrogen fluoride (HF) gas diluted with N 2 gas, fluorine (F 2 ) gas and other fluorine-based gases, hydrogen chloride (HCl) gas and other chlorine-based gases, etc. can be used. As the etching gas, one or more of them can be used. It should be noted that these gases can also be used in combination, H 2 gas and other H-containing gases (reducing gases) can be added to these gases for use, and these gases can be activated by plasma for use. In addition, as the etchant, it can also be in a non-gaseous state, and an etching liquid such as an HF aqueous solution or an HCl aqueous solution can be used. (4) Modification example The order of substrate processing in this mode is not limited to the mode shown in FIG. 4, and can be changed as in the following modification examples. (Modification example 1) In this modification example, instead of step S2b of the above-described second film forming step, step S2c described later is executed. That is, in the above-described second film forming step, the N-containing gas is thermally excited in a non-plasma state to be activated thermally and supplied. The substrate processing order of this modification example can also be shown as follows. (Raw material gas → Gas containing C and N) × m → (Raw material gas → Gas containing N) × n ⇒ Second film / Intermediate layer In this modification, the processing steps and processing conditions in step S2a of the intermediate layer formation step and the second film formation step are respectively set to be the same as those in the intermediate layer formation step and the processing steps and processing conditions in step S2a of the second film formation step shown in FIG. 4. In addition, the processing steps and processing conditions in step S2c are set to be the same as those in step S2b except for the points described later. Among them, in the processing conditions in step S2a, it is more preferable that at least the processing temperature is set to be the same as that in step S2c. [Step S2c] After step S2a is completed, a gas containing N that is activated (i.e., thermally excited) by heating is supplied to the wafer 200 in the processing chamber 201, that is, the third layer formed on the intermediate layer 400. Specifically, the valve 243b is opened, and a gas containing N flows into the gas supply pipe 232b. The gas containing N is flow-regulated by the MFC241b, supplied into the processing chamber 201 via the nozzle 249b, and discharged from the exhaust pipe 231. At the same time, the valve 243e is opened, and an inert gas flows into the gas supply pipe 232e. The inert gas is flow-regulated by the MFC241e and supplied into the processing chamber 201 together with the gas containing N. As the processing conditions when supplying the gas containing N in this step, the following can be exemplified: Processing temperature: 250 to 700 °C, preferably 300 to 650 °C, more preferably 350 to 600 °C; Processing pressure: 1 to 4000 Pa, preferably 1 to 3000 Pa; Gas containing N supply flow rate: 100 to 10000 sccm; Gas containing N supply time: 1 to 120 seconds, preferably 1 to 60 seconds. Other processing conditions can be set to be the same as those when supplying the raw material gas in the intermediate layer formation step. It should be noted that the processing temperature in this step is preferably higher than the processing temperature in step S2b in the above method. By setting the pressure in the processing chamber 201 to such a relatively high pressure range, the gas containing N can be activated thermally in a non-plasma manner. In this modification, the same effects as those in the above method can also be obtained. In addition, in this modification, further, by using a gas containing N that is activated only by thermal excitation, compared with the case of using a gas containing N that is activated by plasma excitation, it is sometimes easier to reduce the amount of C detached from the intermediate layer 400 in the second film formation step and reduce the deviation of the amount of C detached in the plane of the substrate. In addition, even if the content of C per unit area included in the intermediate layer 400 formed in the intermediate layer formation step is reduced, or the deviation of the content of C per unit area included in the intermediate layer 400 formed in the intermediate layer formation step within the substrate surface is reduced, it is easy to make the thickness and the deviation of its distribution of the transition layer 700 after performing the second film formation step into a desired state. (Modification Example 2) In this modification example, as shown in (A) of FIG. 6, after forming a first intermediate layer 400a containing C and N on the first film 300, a second intermediate layer 400b containing N and being a thermal nitrided layer as a cap layer is formed on the first intermediate layer 400a. The second intermediate layer 400b is, for example, a thermal nitrided SiN film. Then, a second film 600 is formed on the second intermediate layer 400b. That is, after performing the first intermediate layer formation step in the same manner as the intermediate layer formation step of the substrate processing sequence shown in FIG. 4 above, a second intermediate layer formation step of thermally activating the N-containing gas is performed. That is, between the intermediate layer formation step and the second film formation step in the substrate processing sequence shown in FIG. 4 above, as the second intermediate layer formation step, the same steps as the second film formation step in Modification Example 1 above are performed (wherein, the number of execution times of the cycle including steps S2a and S2c is different). That is, using an N-containing gas that is activated thermally without using plasma excitation, a second intermediate layer 400b containing N with a C concentration smaller than the C concentration contained in the first intermediate layer 400a or substantially free of C is formed on the first intermediate layer 400a. The substrate processing sequence of this modification example can also be shown as follows. (Source gas → Gas containing C and N) × m → (Source gas → Gas containing N) × p → (Source gas → Gas containing N*) ⇒ Second film / Second intermediate layer / First intermediate layer The processing steps and processing conditions of the first intermediate layer formation step for forming the first intermediate layer 400a are respectively set to be the same as the processing steps and processing conditions of the intermediate layer formation step in the substrate processing sequence shown in FIG. 4 above. In addition, the processing steps and processing conditions of the second intermediate layer formation step for forming the second intermediate layer 400b are set to be the same as the processing steps and processing conditions of the second film formation step (i.e., the thermal nitriding second film formation step) in Modification Example 1 above. In addition, the second film formation step for forming the second film 600 is respectively set to be the same as the processing steps and processing conditions of the second film formation step (i.e., the plasma nitriding second film formation step) in the substrate processing sequence shown in FIG. 4 above. In this modification example, the same effects as those of the above-described method can also be obtained. Further, in this modification example, further, in the second film formation step, the amount of C detached from the first intermediate layer 400a can be reduced. That is, the second intermediate layer 400b can function as a capping layer that reduces or prevents the detachment of C from the first intermediate layer 400a. By forming the second film 600 on the second intermediate layer 400b, a part of the C contained in the first intermediate layer 400a may diffuse into the second intermediate layer 400b. Specifically, for example, as shown in (B) of FIG. 6, in the first intermediate layer 400a and the second intermediate layer 400b, a diffusion layer 500 containing C may be formed by the diffusion of C into the second intermediate layer 400b when the second film 600 is formed. In addition, even if the content of C per unit area contained in the first intermediate layer 400a formed in the first intermediate layer formation step is reduced, it is easy to make the thickness of the transition layer 700 after the second film formation step the desired thickness. Furthermore, in the second intermediate layer formation step of this modification example, for example, the second intermediate layer 400b is formed such that the thickness of the second intermediate layer 400b is larger in the outer region than in the central region within the substrate plane. Thereby, by making the effect of reducing or preventing the detachment of C in the outer region in the second film formation step higher than the effect in the central region, for example, even when the first intermediate layer 400a is formed such that the C content contained in the first intermediate layer 400a becomes uniform within the substrate plane, the transition layer 700 can be made uniform. That is, in the second film formation step, when the amount of C detached in the outer region is larger than that in the central region, it is possible to adjust the amount of C detached from the first intermediate layer 400a to be nearly uniform within the substrate plane. Regarding the thickness of the second intermediate layer 400b, it is preferably set to be less than the thickness of the second film 600 and, for example, a thickness of 5 Å or more, preferably 10 Å or more, more preferably 15 Å or more, and further preferably 20 Å or more. If the thickness of the second intermediate layer 400b is less than 5 Å, it may be difficult to obtain the effect of reducing the detachment of C from the first intermediate layer 400a in the second film formation step using plasma excitation. By making the thickness of the second intermediate layer 400b 5 Å or more, the effect of reducing the detachment of C from the first intermediate layer 400a can be obtained. In addition, by making it 10 Å or more, the effect of reducing the detachment of C from the first intermediate layer 400a can be obtained more reliably. In addition, by making it 15 Å or more, the detachment of C from the first intermediate layer 400a can be substantially prevented. In addition, by making it 20 Å or more, the effect of preventing the detachment of C from the first intermediate layer 400a can be obtained more significantly. It should be noted that in the step of forming the first intermediate layer, the first intermediate layer 400a may be formed in such a manner that its thickness becomes larger in the outer region than in the central region within the plane of the substrate. In the step of forming the second intermediate layer, the second intermediate layer 400b may be formed in such a manner that its thickness becomes larger in the central region than in the outer region within the plane of the substrate. Thus, when the first intermediate layer 400a is concave, the second intermediate layer 400b can be formed as convex to improve the film thickness uniformity within the plane of the substrate. The total film thickness of the first intermediate layer 400a and the second intermediate layer 400b can be made closer to uniform within the plane of the substrate. (Modification 3) In this modification, in the step of forming the intermediate layer, the cycles of the steps of supplying the source gas to the wafer 200, supplying the C-containing gas to the wafer 200, and supplying the N-containing gas to the wafer 200 are performed a specified number of times (m1 times) non-simultaneously, thereby forming the intermediate layer 400 on the first film 300. That is, instead of the step of supplying the C- and N-containing gas in the above step S1b, by separately supplying the C-containing gas and the N-containing gas, a film containing the specified elements, C and N, is formed. At this time, by using a C-containing gas supply system and an N-containing gas supply system instead of the C- and N-containing gas supply system, each gas can be supplied separately. In addition, in this case, as the N-containing gas supply system used in the step of forming the intermediate layer, the N-containing gas supply system used in the step S2b can be used. The substrate processing sequence of this modification can also be shown as follows. (Source gas → C-containing gas → N-containing gas) × m1 → (Source gas → N-containing gas*) × n1 ⇒ Second film / Intermediate layer In the step of supplying the C-containing gas, the supply flow rate of the C-containing gas is set, for example, to a flow rate within the range of 100 to 10,000 sccm. The pressure inside the processing chamber 201 is set, for example, to 1 to 5000 Pa, preferably to a pressure within the range of 1 to 4000 Pa. The time for supplying the C-containing gas to the wafer 200 is set, for example, to 1 to 200 seconds, preferably 1 to 120 seconds, more preferably to a time within the range of 1 to 60 seconds. Other processing conditions are set, for example, to the same processing conditions as in the step of forming the intermediate layer in the above-described embodiment. As the C-containing gas in this modification, for example, a hydrocarbon-based gas can be used. A hydrocarbon-based gas can also be said to be a substance composed of only two elements, C and H. As the hydrocarbon-based gas, for example, propylene (C 3 H 6 ) gas, etc. can be used. In addition, as the C-containing gas in this modification, as in the above-described embodiment, for example, a C- and N-containing gas can also be used. The treatment steps and conditions of the step of supplying the N-containing gas in the intermediate layer formation step are set to be the same as the treatment steps and conditions in step S2c in the above-described Modification 1. In addition, the treatment steps and conditions of the step of supplying the source gas in the intermediate layer formation step and the treatment steps and conditions of the second film formation step are respectively set to be the same as the treatment steps and conditions of the corresponding steps in the above-described method. In this modification, the same effects as those in the above-described embodiment can also be obtained. In addition, in the intermediate layer formation step, the C-containing gas as the C source and the N-containing gas as the N source can be supplied to the wafer 200 as separate gases, respectively. Therefore, by adjusting the supply conditions (such as supply flow rate, supply time, pressure during supply, etc.) of the C-containing gas and the N-containing gas, it is easier to control the amounts (concentrations) of C and N contained in the intermediate layer. (Modification 4) In this modification, different source gases are used in the intermediate layer formation step and the second film formation step in the above-described substrate treatment timing. The substrate treatment sequence of this modification can be shown as follows. (First source gas → C- and N-containing gas) × m → (Second source gas → N-containing gas*) × n ⇒ Second film / Intermediate layer (First source gas → C- and N-containing gas) × m → (Second source gas → N-containing gas) × n ⇒ Second film / Intermediate layer (First source gas → C-containing gas → N-containing gas) × m1 → (Second source gas → N-containing gas*) × n1 ⇒ Second film / Intermediate layer Furthermore, in this modification, different source gases are used in the first intermediate layer formation step, the second intermediate layer formation step, and the second film formation step in the above-described substrate treatment sequence. The substrate treatment sequence of this modification can be shown as follows. Any two of the first to third source gases can be the same gas. (First source gas → C- and N-containing gas) × m → (Second source gas → N-containing gas) × p → (Third source gas → N-containing gas*) ⇒ Second film / Second intermediate layer / First intermediate layer In this modification, the same effects as those in the above-described method can also be obtained. <Other methods> Above, one method of the present invention has been specifically described. However, the present invention is not limited to the above-described method, and various changes can be made without departing from the gist thereof. For example, in the above-described method, the case where the intermediate layer formation step and the second film formation step are continuously performed (in-situ) in the same processing chamber 201 has been described. The present invention is not limited to this, and the intermediate layer formation step and the second film formation step can also be respectively performed (ex-situ) in different processing chambers (processing containers). In this case, the same effects as those in the above-described method can also be obtained. In the above-described manner, an example of treating a film using a batch-type substrate processing apparatus that processes multiple substrates at once has been described. The present invention is not limited to the above-described manner, and for example, it can also be suitably applied to a case of treating a film using a single-wafer type substrate processing apparatus that processes one or more substrates at once. Further, in the above-described manner, an example of treating a film using a substrate processing apparatus having a hot-wall type processing furnace has been described. The present invention is not limited to the above-described manner, and it can also be suitably applied when treating a film using a substrate processing apparatus having a cold-wall type processing furnace. When using these substrate processing apparatuses, each process can also be performed by the same processing steps and processing conditions as those in the above-described manner and modified examples, and the same effects as those in the above-described manner and modified examples can be obtained. Further, the above-described manner and modified examples can be suitably combined and used. The processing steps and processing conditions at this time can be set to be the same as those of the processing steps and processing conditions in the above-described manner and modified examples, for example. [Examples] Hereinafter, experimental results verifying the effects obtained by the above-described manner and modified examples will be described. The processing conditions in each step when producing the evaluation samples were set to the specified processing conditions within the range of the processing conditions in each step of the above-described manner. FIG. 7 shows the evaluation results of the etching resistance (processability) of evaluation samples 1 to 5 of films having different thicknesses of the intermediate layer 400. In evaluation samples 1 to 4, using the substrate processing apparatus of the above-described manner, a SiCN layer was formed as an intermediate layer on the SiO film formed on the substrate surface by the substrate processing sequence shown in FIG. 4, and a plasma-nitrided SiN film was formed on the SiCN layer. In evaluation samples 1 to 4, the thicknesses of the SiCN layers were set to 2 Å, 4 Å, 6 Å, and 7 Å, respectively. In evaluation sample 5, using the substrate processing apparatus of the above-described manner, without performing the intermediate layer formation step of the substrate processing sequence shown in FIG. 4, after forming a thermally nitrided SiN layer having a film thickness of 23 Å on the first film, the second film formation step was performed, and thus a plasma-nitrided SiN film was formed on the SiO film formed on the substrate surface. Then, the etching resistance (processability) of the films of evaluation samples 1 to 5 was measured, respectively. FIG. 7 is a diagram showing the depth profile of the wet etching rate (WER) when etching the films in each evaluation sample using a 1% HF aqueous solution. The vertical axis of FIG. 7 represents the WER (Å / min) of each film (layer). The horizontal axis of FIG. 7 represents the total thickness (Å) of each film (layer). The interface between the SiO film and the SiCN layer exists at a position within the range of 20 to 25 (Å) on the horizontal axis. As shown in Fig. 7, the change in the WER (change in etching resistance) of the films of evaluation samples 3 and 4 is smaller than the change in the WER (change in etching resistance) of the films of evaluation samples 1, 2, and 5. That is, it can be seen that the width (thickness) of the transition layer of evaluation samples 3 and 4 is smaller than the width (thickness) of the transition layer of evaluation samples 1, 2, and 5. That is, it is confirmed that by increasing the thickness of the intermediate layer, the thickness of the transition layer can be reduced, and by adjusting the thickness of the intermediate layer 400, the thickness of the transition layer can be adjusted. Fig. 8 shows the evaluation results of the etching resistance (processability resistance) of the films of evaluation sample 6 and evaluation sample 7 on the central side and the peripheral side of the substrate. In evaluation sample 6, using the substrate processing apparatus of the above-described manner, a SiCN layer is formed as an intermediate layer on the SiO film formed on the substrate surface by the substrate processing sequence shown in Fig. 4. A SiN film is formed on the SiCN layer. In evaluation sample 6, the film thickness of the SiCN layer is formed to be thicker in the outer region than in the central region in the plane of the substrate. In evaluation sample 7, using the substrate processing apparatus in the above-described manner, a SiCN layer is formed as an intermediate layer on the SiO film formed on the substrate surface by the substrate processing sequence shown in Fig. 4, and a SiN film is formed on the SiCN layer. In evaluation sample 7, the film thickness of the SiCN layer is formed to be uniform in the plane of the substrate. Then, the etching resistance (processability resistance) of the films of evaluation sample 6 and evaluation sample 7 on the central side of the substrate surface and the etching resistance (processability resistance) on the peripheral side of the substrate surface are measured, respectively. Fig. 8 is a graph showing the WER when etching the films in evaluation sample 6 and evaluation sample 7 with a 1% HF aqueous solution. The vertical axis of Fig. 8 represents the WER (Å / min) of the film. The horizontal axis of Fig. 8 represents the total thickness (Å) of each film (layer). The interface with the SiO film exists at a position where the horizontal axis is in the range of 20 to 25 (Å). As shown in Fig. 8, regarding the WER of the films with different in-plane film thickness distributions of evaluation sample 6, compared with the WER of the films with uniform in-plane film thickness distributions of evaluation sample 7, the difference in WER between the central side and the peripheral side of the substrate is smaller. That is, it is confirmed that when the intermediate layer is formed in a manner with different in-plane film thickness distributions, compared with the case where the in-plane film thickness distribution becomes uniform, the difference in WER between the central side and the peripheral side in the plane of the substrate can be reduced. 200: Wafer (substrate) [Fig. 1] is a schematic configuration diagram of a vertical processing furnace of a substrate processing apparatus preferably used in one embodiment of the present invention, and is a diagram showing the processing furnace portion in a longitudinal sectional view. [Fig. 2] is a schematic configuration diagram of a vertical processing furnace of a substrate processing apparatus preferably used in one embodiment of the present invention, and is a diagram showing the processing furnace portion in a sectional view taken along line A-A of Fig. 1. [Fig. 3] is a schematic configuration diagram of a controller of a substrate processing apparatus preferably used in one embodiment of the present invention, and is a diagram showing the control system of the controller in a block diagram. [Fig. 4] is a flowchart showing a substrate processing procedure preferably used in one embodiment of the present invention. (A) in [Fig. 5] and (B) in [Fig. 5] are diagrams showing an example of the cross-sectional structure of a film formed on a substrate. (A) in [Fig. 6] and (B) in [Fig. 6] are diagrams showing the cross-sectional structure of a film formed on a substrate in a modified example. [Fig. 7] is a diagram showing the evaluation result of the etching resistance of a film formed on a substrate. [Fig. 8] is a diagram showing the evaluation result of the etching resistance of the central region and the outer region in the plane of a film formed on a substrate.

Claims

1. A substrate processing method, comprising: (a) A process of forming a carbon-containing intermediate layer on a first film formed on a substrate; (b) A process of forming a second nitrogen-containing film on the aforementioned intermediate layer using a nitrogen-containing gas activated by plasma excitation, wherein, in (a), the aforementioned intermediate layer is formed in such a way that the carbon content per unit area contained in the aforementioned intermediate layer is different in the central region and the outer region of the central region within the aforementioned substrate surface.

2. The substrate processing method as described in claim 1, wherein, In (a), the aforementioned intermediate layer is formed such that the carbon content per unit area contained in the aforementioned intermediate layer increases in the aforementioned outer region compared to the aforementioned central region.

3. The substrate processing method as described in claim 1, wherein, In (a), the aforementioned intermediate layer is formed in a manner that differs in the thickness of the aforementioned intermediate layer in the aforementioned central region and in the aforementioned outer region.

4. The substrate processing method as described in claim 1, wherein, In (a), the aforementioned intermediate layer is formed such that the thickness of the aforementioned intermediate layer increases in the aforementioned outer region compared to the aforementioned central region.

5. The substrate processing method as described in claim 4, wherein, In (b), the aforementioned second membrane is formed such that the thickness of the aforementioned second membrane increases in the aforementioned central region compared to the aforementioned outer region.

6. The substrate processing method as described in claim 1, wherein, In (a), the aforementioned intermediate layer is formed in a manner in which the concentration of carbon contained in the aforementioned intermediate layer differs between the aforementioned central region and the aforementioned outer region.

7. The substrate processing method as described in claim 1, wherein, In (a), the aforementioned intermediate layer is formed such that the concentration of carbon contained in the aforementioned intermediate layer is greater in the aforementioned outer region compared to the aforementioned central region.

8. A substrate processing method, comprising: (a) A process of forming a carbon-containing intermediate layer on a first film formed on a substrate; (b) A process of forming a second nitrogen-containing film on the aforementioned intermediate layer using an activated nitrogen-containing gas, wherein, in (a), the aforementioned intermediate layer is formed in such a way that the carbon content per unit area contained in the aforementioned intermediate layer is different in the central region and the outer region of the central region in the aforementioned substrate surface, and in (b), at least a portion of the carbon contained in the aforementioned intermediate layer is detached from the aforementioned intermediate layer.

9. The substrate processing method as described in claim 8, wherein, In (b), carbon is removed from the aforementioned intermediate layer in a manner that differs between the amount of carbon per unit area removed from the aforementioned intermediate layer in the aforementioned central region and in the aforementioned outer region.

10. The substrate processing method as described in claim 8, wherein, In (a), the intermediate layer is formed such that the carbon content per unit area contained in the intermediate layer is greater in the outer region compared to the central region. In (b), carbon is removed from the intermediate layer such that the amount of carbon per unit area removed from the intermediate layer is greater in the outer region compared to the central region.

11. A substrate processing method, comprising: (a) A process of forming a carbon-containing intermediate layer on a first film formed on a substrate; (b) A process of forming a nitrogen-containing second film on the aforementioned intermediate layer using a nitrogen-containing gas activated by plasma excitation; After the execution of (b), a transition layer with an etch resistance different from that of the aforementioned first film and the aforementioned second film is formed between the aforementioned first film and the aforementioned second film; In (a), the distribution of carbon content per unit area contained in the aforementioned intermediate layer is set in such a way that the thickness of the aforementioned transition layer is a predetermined distribution within the aforementioned substrate surface, and the aforementioned intermediate layer is formed in such a way that the carbon content per unit area contained in the aforementioned intermediate layer is different in the central region and the outer region of the central region within the aforementioned substrate surface.

12. The substrate processing method as described in claim 1, wherein, In (b), the aforementioned activated nitrogen-containing gas is supplied from the aforementioned outer region toward the aforementioned central region.

13. The substrate processing method as described in claim 8, wherein, In (b), the aforementioned nitrogen-containing gas is activated thermally by heating.

14. The substrate processing method as described in claim 1, wherein, During the period from the execution of (a) to the start of (b), the process of forming a carbon-free nitrogen-containing layer on the aforementioned intermediate layer without plasma excitation is not performed.

15. The substrate processing method as described in claim 1, wherein, The aforementioned substrate processing method further includes: (c) between (a) and (b), using a nitrogen-containing gas that is activated thermally without plasma excitation to form a second intermediate layer containing nitrogen with a lower carbon concentration or no carbon in the aforementioned intermediate layer.

16. The substrate processing method as described in claim 15, wherein, In (c), the aforementioned second intermediate layer is formed such that the thickness of the aforementioned second intermediate layer is greater in the aforementioned outer region compared to the aforementioned central region.

17. A method for manufacturing a semiconductor device, comprising the steps of a substrate processing method as described in any one of claims 1, 8, and 11.

18. A program for a substrate processing apparatus to perform the following steps by means of a computer: (a) forming a carbon-containing intermediate layer on a first film formed on a substrate; (b) forming a nitrogen-containing second film on the intermediate layer using a nitrogen-containing gas activated by plasma excitation; and in (a) forming the intermediate layer in a manner in which the carbon content per unit area contained in the intermediate layer differs in the central region of the substrate surface and in the outer region of the central region.

19. A substrate processing apparatus comprising: a carbon-containing gas supply system for supplying carbon-containing gas to a substrate; a nitrogen-containing gas supply system for supplying nitrogen-containing gas to the substrate; an activation mechanism for activating the nitrogen-containing gas by plasma excitation; and a control unit configured to control the carbon-containing gas supply system, the nitrogen-containing gas supply system, and the activation mechanism to perform: (a) a process of forming a carbon-containing intermediate layer on a first film formed on the substrate by supplying the carbon-containing gas activated by plasma excitation to the substrate; and (b) a process of forming a nitrogen-containing second film on the intermediate layer by supplying the activated nitrogen-containing gas to the substrate, wherein, In (a), the aforementioned intermediate layer is formed in such a way that the carbon content per unit area contained in the aforementioned intermediate layer is different in the central region of the aforementioned substrate surface and in the outer region of the central region.

20. A program for a substrate processing apparatus to perform the following steps by means of a computer: (a) forming a carbon-containing intermediate layer on a first film formed on a substrate; (b) forming a nitrogen-containing second film on the intermediate layer using an activated nitrogen-containing gas, wherein in (a) the intermediate layer is formed in such a way that the carbon content per unit area contained in the intermediate layer is different in the central region of the substrate surface and in the outer region of the central region, and in (b) at least a portion of the carbon contained in the intermediate layer is detached from the intermediate layer.

21. A substrate processing apparatus comprising: a carbon-containing gas supply system for supplying carbon-containing gas to a substrate; a nitrogen-containing gas supply system for supplying nitrogen-containing gas to the substrate; an activation mechanism for activating the nitrogen-containing gas; and a control unit configured to control the carbon-containing gas supply system, the nitrogen-containing gas supply system, and the activation mechanism to perform: (a) a process of forming a carbon-containing intermediate layer on a first film formed on the substrate by supplying the carbon-containing gas activated by plasma excitation to the substrate; and (b) a process of forming a nitrogen-containing second film on the intermediate layer by supplying the activated nitrogen-containing gas to the substrate, wherein, In (a), the aforementioned intermediate layer is formed in such a way that the carbon content per unit area contained in the aforementioned intermediate layer is different in the central region and the outer region of the central region within the aforementioned substrate surface; in (b), at least a portion of the carbon contained in the aforementioned intermediate layer is detached from the aforementioned intermediate layer.

22. A program that uses a computer to cause a substrate processing apparatus to perform the following steps: (a) forming a carbon-containing intermediate layer on a first film formed on a substrate; (b) forming a nitrogen-containing second film on the intermediate layer using a nitrogen-containing gas activated by plasma excitation; after execution of (b), forming a transition layer between the first film and the second film with an etch resistance different from that of the first film and the second film; in (a), setting the distribution of carbon content per unit area contained in the intermediate layer in such a way that the thickness of the transition layer is a predetermined distribution within the substrate surface; in (a), forming the intermediate layer in such a way that the carbon content per unit area contained in the intermediate layer is different in the central region and the outer region of the central region within the substrate surface.

23. A substrate processing apparatus comprising: a carbon-containing gas supply system for supplying carbon-containing gas to a substrate; a nitrogen-containing gas supply system for supplying nitrogen-containing gas to the substrate; an activation mechanism for activating the nitrogen-containing gas; and a control unit configured to control the carbon-containing gas supply system, the nitrogen-containing gas supply system, and the activation mechanism to perform: (a) a process of forming a carbon-containing intermediate layer on a first film formed on the substrate by supplying the carbon-containing gas activated by plasma excitation to the substrate; and (b) a process of forming a nitrogen-containing second film on the intermediate layer by supplying the activated nitrogen-containing gas to the substrate, wherein, After execution of (b), a transition layer with an etch resistance different from that of the first and second films is formed between the first and second films. In (a), the distribution of carbon content per unit area contained in the intermediate layer is set in such a way that the thickness of the transition layer is distributed in a predetermined manner within the substrate surface. In (a), the intermediate layer is formed in such a way that the carbon content per unit area contained in the intermediate layer is different in the central region and the outer region of the central region within the substrate surface.

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