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

Abstract

The present invention provides a technique for improving the surface flatness and surface roughness of a film formed on a substrate. It comprises: (a) a step of forming a film by supplying a first gas and a second gas to a substrate; and (b) a step of improving the surface flatness of the film.

Description

Substrate processing method, semiconductor device manufacturing method, program and substrate processing device The present invention relates to a substrate processing method, a semiconductor device manufacturing method, a program and a substrate processing device. As one of the steps in manufacturing semiconductor devices, a process of forming a film on a substrate is sometimes performed (for example, see Patent Document 1). [Prior Art Document] [Patent Document] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-118462 (Problems that the invention aims to solve) The present invention provides a technology that can improve the surface flatness of a film formed on a substrate and improve the surface roughness of the film. (Technical Means for Solving the Problem) According to one aspect of the present invention, a technique is provided that comprises: (a) supplying a first gas and a second gas to a substrate to form a film; and (b) improving the flatness of the surface of the film. (Compared to the effects of the prior art) According to the present invention, the flatness of the surface of a film formed on a substrate can be improved, and the surface roughness of the film can be improved. <One Aspect of the Present Invention> Below, one aspect of the present invention will be described primarily with reference to Figures 1 to 4 . The figures used in the following description are schematic diagrams, and the dimensional relationships and ratios of the elements shown in the figures may not necessarily correspond to actual conditions. Furthermore, the dimensional relationships and ratios of the elements may not necessarily correspond across multiple figures. (1) Configuration of the Substrate Processing Apparatus As shown in FIG1 , a processing furnace 202 includes a heater 207 serving as a temperature adjustment unit (heating unit). Heater 207 is cylindrical and vertically mounted by being supported on a holding plate. Heater 207 also functions as an activation mechanism (excitation unit) that activates (excites) gas using heat. A reaction tube 203 is provided inside the heater 207 in a concentric circle with the heater 207. The reaction tube 203 is made of, for example, quartz (SiO 2) or silicon carbide (SiC) or other heat-resistant materials, and is formed into a cylindrical shape with a closed upper end and an open lower end. Below the reaction tube 203, a manifold 209 is provided concentrically with the reaction tube 203. The manifold 209 is made of a metal material such as stainless steel (SUS) and is formed into a cylindrical shape with an upper end and a lower end open. The upper end of the manifold 209 is joined to the lower end of the reaction tube 203 to support the reaction tube 203. An O-ring 220a is provided between the manifold 209 and the reaction tube 203 as a sealing member. The reaction tube 203 is installed vertically in the same manner as the heater 207. The reaction tube 203 and the manifold 209 constitute a processing container (reaction container). A processing chamber 201 is formed in the hollow portion of the cylinder of the processing container. The processing chamber 201 is configured to accommodate a wafer 200 as a substrate. The wafer 200 is processed in the processing chamber 201. Within the processing chamber 201, nozzles 249a and 249b are provided, respectively, to penetrate the sidewalls of the manifold 209, serving as the first and second supply units. Nozzles 249a and 249b are also referred to as the first and second nozzles, respectively. Nozzles 249a and 249b are made of a heat-resistant material such as quartz or SiC. Gas supply pipes 232a and 232b are connected to nozzles 249a and 249b, respectively. Nozzles 249a and 249b are positioned adjacent to each other. Gas supply pipes 232a and 232b are provided, in order from the upstream side of the airflow, with mass flow controllers (MFCs) 241a and 241b, respectively, which are flow controllers (flow control units), and valves 243a and 243b, which are on-off valves. Gas supply pipe 232c is connected to gas supply pipe 232a downstream of valve 243a. MFC 241c and valve 243c are provided to gas supply pipe 232c in order from the upstream side of the airflow. Gas supply pipe 232d is connected to gas supply pipe 232b downstream of valve 243b. MFC 241d and valve 243d are provided to gas supply pipe 232d in order from the upstream side of the airflow. Gas supply pipes 232a to 232d are made of a metal material such as SUS. As shown in Figure 2, nozzles 249a and 249b are positioned in the annular space between the inner wall of the reaction tube 203 and the wafers 200 when viewed from above, extending upward from the lower portion of the inner wall of the reaction tube 203 toward the upper portion, in the direction in which the wafers 200 are arranged. Specifically, nozzles 249a and 249b are positioned along the wafer arrangement area, in an area horizontally surrounding the wafer arrangement area to the sides of the reaction tube 203. Gas supply holes 250a and 250b are provided on the sides of the nozzles 249a and 249b, respectively, for supplying gas. The gas supply holes 250a and 250b each open toward the center of the wafer 200 when viewed from above, enabling gas to be supplied toward the wafers 200. Multiple gas supply holes 250a and 250b are provided from the bottom to the top of the reaction tube 203. The first gas is supplied from the gas supply pipe 232a through the MFC 241a, the valve 243a, and the nozzle 249a into the processing chamber 201. The first gas functions as a source gas, which is one of the film-forming gases. The second gas is supplied from the gas supply pipe 232b through the MFC 241b, the valve 243b, and the nozzle 249b into the processing chamber 201. The second gas functions as a dopant gas, which is one of the film-forming gases. Inert gas is supplied from gas supply pipes 232c and 232d through MFCs 241c and 241d, valves 243c and 243d, gas supply pipes 232a and 232b, and nozzles 249a and 249b into the processing chamber 201. The inert gas functions as a purge gas, a carrier gas, a dilution gas, and the like. The first gas supply system primarily comprises gas supply pipe 232a, MFC 241a, and valve 243a. The second gas supply system primarily comprises gas supply pipe 232b, MFC 241b, and valve 243b. The inert gas supply system primarily comprises gas supply pipes 232c and 232d, MFCs 241c and 241d, and valves 243c and 243d. The nozzles connected to the gas supply pipes constituting each of these supply systems may also be incorporated into each of these supply systems. Any or all of the various supply systems described above can be configured as an integrated supply system 248 that integrates valves 243a-243d, MFCs 241a-241d, and the like. Integrated supply system 248 is connected to gas supply pipes 232a-232d, respectively, and is configured so that the supply of various substances (gases) into gas supply pipes 232a-232h, namely, the opening and closing of valves 243a-243d, and the flow rate adjustment by MFCs 241a-241d, are controlled by controller 121 (described later). Integrated supply system 248 is configured as an integrated or split integrated unit, which can be attached to and detached from gas supply pipes 232a-232d, etc., and can be maintained, replaced, or expanded, etc., on an integrated unit basis. An exhaust port 231a for exhausting the atmosphere within the processing chamber 201 is provided at the lower sidewall of the reaction tube 203. The exhaust port 231a can also be provided from the lower portion of the sidewall of the reaction tube 203 along the upper portion, i.e., along the wafer array area. An exhaust pipe 231 is connected to the exhaust port 231a. The exhaust pipe 231 is made of a metal material such as SUS. The exhaust pipe 231 is connected to a vacuum pump 246, which serves as a vacuum exhaust device, via a pressure sensor 245, which serves as a pressure detector (pressure detection unit) for detecting the pressure within the processing chamber 201, and an APC (Auto Pressure Controller) valve 244, which serves as a pressure regulator (pressure adjustment unit). The APC valve 244 is configured to enable and disable vacuum exhaust within the processing chamber 201 by opening and closing the valve while the vacuum pump 246 is in operation. Furthermore, the pressure within the processing chamber 201 can be adjusted by adjusting the valve opening based on pressure information detected by the pressure sensor 245 while the vacuum pump 246 is in operation. The exhaust system mainly comprises the exhaust pipe 231, the APC valve 244, and the pressure sensor 245. A vacuum pump 246 may also be included in the exhaust system. A sealing cover 219 is provided below the manifold 209 as a furnace port cover that can airtightly seal the lower end opening of the manifold 209. The sealing cover 219 is formed of a metal material such as SUS and is formed into a disc shape. An O-ring 220b is provided on the upper surface of the sealing cover 219 as a sealing member that abuts the lower end of the manifold 209. A rotating mechanism 267 is provided below the sealing cover 219 to rotate the wafer boat 217 described later. The rotating shaft 255 of the rotating mechanism 267 is formed of a metal material such as SUS and passes through the sealing cover 219 to be connected to the wafer boat 217. The rotating mechanism 267 is configured to rotate the wafer 200 by rotating the wafer boat 217. The sealing cover 219 is configured to be raised and lowered in the vertical direction by the wafer boat elevator 115, which is provided outside the reaction tube 203 and serves as an elevating mechanism. The boat elevator 115 serves as a transport system (transport mechanism) that carries (transports) the wafers 200 into and out of the processing chamber 201 by raising and lowering the sealing cap 219 . A shutter 219s, serving as a furnace cover, is installed below the manifold 209. This shutter 219s acts as a furnace port cover and can airtightly seal the lower opening of the manifold 209 when the sealing cover 219 is lowered to remove the wafer boat 217 from the processing chamber 201. The shutter 219s is formed of a metal material, such as SUS, and is disc-shaped. An O-ring 220c, serving as a sealing member, is installed on the upper surface of the shutter 219s and abuts against the lower end of the manifold 209. The shutter 219s's opening and closing movements (such as lifting and rotating movements) are controlled by the shutter opening and closing mechanism 115s. The wafer boat 217, serving as a substrate support, is configured to support multiple wafers 200, for example, 25 to 200, in a horizontal position, aligned with their centers, and arranged vertically in multiple stages, i.e., spaced apart. The wafer boat 217 is made of a heat-resistant material such as quartz or SiC. Heat shields 218, also made of a heat-resistant material such as quartz or SiC, are supported in multiple stages at the bottom of the wafer boat 217. A temperature sensor 263 is installed inside the reaction tube 203 as a temperature detector. The power level to the heater 207 is adjusted based on the temperature information detected by the temperature sensor 263, thereby maintaining the desired temperature distribution within the processing chamber 201. The temperature sensor 263 is installed along the inner wall of the reaction tube 203. As shown in FIG3 , the controller 121 belonging to the control unit (control means) is configured as a computer having a CPU (Central Processing Unit) 121a, a RAM (Random Access Memory) 121b, a memory device 121c, and an I / O (Input / Output) 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 such as a touch panel is connected to the controller 121. In addition, an external memory device 123 can be connected to the controller 121. In addition, the substrate processing apparatus can be configured to have one control unit or a plurality of control units. That is, the control for performing the processing sequence described later can be performed using one control unit or a plurality of control units. Furthermore, multiple control units may constitute a control system interconnected via a wired or wireless communication network, or the control system as a whole may control the processing sequence described below. In this specification, when the term "control unit" is used, it may include not only a single control unit but also a plurality of control units or a control system composed of a plurality of control units. The memory device 121c is composed of, for example, a flash memory, an HDD (Hard Disk Drive), an SSD (Solid State Drive), etc. The control program for controlling the action of the substrate processing device, the process recipe that records the program or conditions for the substrate processing described later, etc. are recorded and stored in a readable manner in the memory device 121c. The process recipe is composed in a manner that enables the substrate processing device to execute each program in the substrate processing described later and obtain a predetermined result using the controller 121, and functions as a program. Hereinafter, process recipes or control programs may also be simply referred to as programs. In addition, process recipes are referred to as recipes. When the term program is used in this specification, sometimes only the process unit is included, sometimes only the control program unit is included, or sometimes both of the above are included. RAM121b is configured as a memory area that temporarily holds programs or data read by CPU121a. The I / O port 121d is connected to the MFCs 241a to 241d, valves 243a to 243d, pressure sensor 245, APC valve 244, vacuum pump 246, temperature sensor 263, heater 207, rotation mechanism 267, boat elevator 115, shutter opening and closing mechanism 115s, and the like. The CPU 121a is configured to read and execute a control program from the memory device 121c, and to read a recipe from the memory device 121c based on input of an operation command from the input / output device 122. In accordance with the contents of the read recipe, the CPU 121a is configured to control the flow rate adjustment of various substances (gases) by the MFCs 241a to 241e, the opening and closing of the valves 243a to 243d, the opening and closing of the APC valve 244 and the pressure adjustment by the APC valve 244 using the pressure sensor 245, the starting and stopping of the vacuum pump 246, the temperature adjustment of the heater 207 using the temperature sensor 263, the rotation and rotation speed adjustment of the wafer boat 217 by the rotation mechanism 267, the raising and lowering of the wafer boat 217 by the wafer elevator 115, and the opening and closing of the shutter 219s by the shutter opening and closing mechanism 115s. The controller 121 can be constructed by installing the above-mentioned program recorded and stored in the external memory device 123 on a computer. The external memory device 123 includes, for example, magnetic disks such as HDD, optical disks such as CD (Compact Disc), optical disks such as MO (Magneto Optical), USB (Universal Serial Bus) memory, semiconductor memory such as SSD, etc. The memory device 121c and the external memory device 123 constitute a recording medium that can be read by a computer. Hereinafter, they are also simply referred to as recording media. When the term recording medium is used in this specification, sometimes only the memory device 121c alone is included, sometimes only the external memory device 123 alone is included, or sometimes both of them are included. In addition, instead of using the external memory device 123, a communication means such as a network or a dedicated line can be used to provide the program to the computer. (2) Substrate Processing Step Using the aforementioned substrate processing apparatus, a method for processing a substrate, that is, an example of a process sequence for forming a film on a wafer 200 serving as a substrate, will be described primarily with reference to FIG4 . In the following description, the operations of the various components constituting the substrate processing apparatus are controlled by a controller 121 . The processing sequence in this embodiment includes: (a) step A of supplying a first gas and a second gas to the wafer 200 to form a film; and (b) step B of improving the flatness of the surface of the film. Hereinafter, an example will be described in which a loop in which step A and step B are not performed simultaneously is performed a predetermined number of times (m times, where m is an integer of 1 or 2 or greater). Hereinafter, an example will be described in which a cycle including step B1 of removing gas from the space where the wafer 200 is located and step B2 of supplying an inert gas is performed a predetermined number of times (n times, where n is an integer greater than or equal to 1 or 2) in step B. In addition, the following description will be given of an example in which a predetermined seed crystal film is formed in advance on the surface of the wafer 200 . 4 , a represents step A, b represents step B, b1 represents step B1, and b2 represents step B2. In this specification, for convenience, the above-mentioned processing sequence may be expressed as follows. The same expression is also used in the following description of modified examples or other aspects. {(first gas + second gas) → (gas removal → inert gas) × n} × m The term "wafer" used in this specification sometimes refers to the wafer itself, and sometimes refers to a laminate of a wafer and a predetermined layer or film formed on its surface. The term "surface of the wafer" used in this specification sometimes refers to the surface of the wafer itself, and sometimes refers to the surface of a predetermined layer, etc. formed on the wafer. When it is stated in this specification that "a predetermined layer is formed on the wafer", it sometimes refers to forming the predetermined layer directly on the surface of the wafer itself, and sometimes refers to forming the predetermined layer on the layer formed on the wafer, etc. The use of the term "substrate" in this specification is also synonymous with the use of the term "wafer". The term "layer" used in this specification includes at least one of a continuous layer and a discontinuous layer. (Wafer Filling and Boat Loading) When multiple wafers 200 are loaded into the wafer boat 217 (wafer filling), the shutter 219s is moved by the shutter opening and closing mechanism 115s, opening the lower end of the manifold 209. Then, as shown in FIG1 , the wafer boat 217, supporting multiple wafers 200, is lifted by the boat elevator 115 and loaded into the processing chamber 201 (boat loading). In this state, the seal cap 219 seals the lower end of the manifold 209 via the O-ring 220b. In this manner, the wafers 200 are prepared (provided) within the processing chamber 201. (Pressure Adjustment and Temperature Adjustment) After the wafer boat is loaded, vacuum exhaust (decompression exhaust) is performed using the vacuum pump 246 to reduce the pressure (vacuum degree) in the processing chamber 201, i.e., the space where the wafer 200 is located. At this time, the pressure in the processing chamber 201 is measured by the pressure sensor 245, and the APC valve 244 is feedback-controlled based on the measured pressure information. In addition, heating is performed using the heater 207 to reduce the wafer 200 in the processing chamber 201 to the required processing temperature. At this time, feedback control is performed on the power supply level to the heater 207 based on the temperature information detected by the temperature sensor 263 to achieve the required temperature distribution in the processing chamber 201. In addition, the rotation of the wafer 200 by the rotation mechanism 267 is started. The exhaust in the processing chamber 201, the heating and rotation of the wafer 200 are all continued for at least until the processing of the wafer 200 is completed. (Film Forming Step: Step A) In this step, the first gas and the second gas are supplied to the wafer 200 in the processing chamber 201 . Specifically, valves 243a and 243b are opened to allow the first gas and the second gas to flow into the gas supply pipes 232a and 232b, respectively. The first gas and the second gas are respectively adjusted in flow rate by MFCs 241a and 241b, supplied into the processing chamber 201 through nozzles 249a and 249b, mixed within the processing chamber 201, and exhausted from the exhaust port 231a. At this time, the first gas and the second gas are supplied to the wafer 200 from the side of the wafer 200 (first gas + second gas supply). At this time, valves 243c and 243d can also be opened to supply an inert gas into the processing chamber 201 through nozzles 249a and 249b, respectively. As the processing conditions when supplying the first gas and the second gas in this step, the following can be cited as examples: Processing temperature: 300~500℃, preferably 350~450℃ Processing pressure: 100~1000Pa, preferably 200~700Pa First gas supply flow rate: 0.5~3slm, preferably 0.8~2slm Second gas supply flow rate: 0.001~0.02slm, preferably 0.005~0.01slm Inert gas supply flow rate (for each gas supply pipe): 0~20slm Supply time of each gas: 1~300 minutes The processing conditions shown here are conditions for the first gas and the second gas to undergo gas phase decomposition (thermal decomposition) when the first gas and the second gas exist separately in the processing chamber 201, that is, conditions for a CVD reaction to occur. That is, the processing conditions shown here are conditions that do not impose self-limitation on the adsorption (deposition) of the first gas and the second gas on the surface of the wafer 200, that is, the adsorption of the first gas and the second gas on the wafer 200 becomes non-self-limiting. In addition, in this specification, the expression of a numerical range such as "300~500℃" means that the lower limit and the upper limit are included in the range. Therefore, for example, "300~500℃" means "above 300℃ and below 500℃". The same applies to other numerical ranges. In addition, the processing temperature in this specification refers to the temperature of the wafer 200 or the temperature in the processing chamber 201, and the processing pressure refers to the pressure in the processing chamber 201, in other words, the pressure of the space where the wafer 200 is located. In addition, the processing time refers to the time for continuing the processing. In addition, when the supply flow rate includes 0slm, 0slm means that the substance (gas) is not supplied. This is also the same in the following description. By supplying the first gas and the second gas to the wafer 200 under the above-mentioned processing conditions, the first gas and the second gas can be decomposed in the gas phase respectively, so that at least a portion of the molecular structure of the molecules constituting the first gas and at least a portion of the molecular structure of the molecules constituting the second gas are adsorbed (deposited) on the surface of the wafer 200, that is, on the seed film formed on the wafer 200, thereby forming a film. As the first gas, a gas containing a compound represented by the formula M1Rx can be used. Here, M1 is the first element, R is a group (also known as a residue, substituent, or ligand), and x is an integer greater than or equal to 1. As the first gas, a gas containing the first element and one or more R groups bonded to the first element in one molecule can be used. Furthermore, R is selected from hydrogen, an alkyl group, a halogen element, and the like. As the first gas, for example, monosilane (SiH) containing silicon (Si) as the first element and hydrogen (H) as R 4) Gas, disilane (Si 2H 6) Gas, trisilane (Si 3H 8) Gas, tetrasilane (Si 4H 10 ) gas, pentasilane (Si 5H 12 ) gas, hexasilane (Si 6H 14 As the first gas, one or more of these can be used. As the first gas, for example, a halosilane gas containing Si as the first element and a halogen as R can be used. Halogens include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), etc. As the first gas, for example, monochlorosilane (SiH 3Cl) gas, dichlorosilane (SiH 2Cl 2) Gas, trichlorosilane (SiHCl 3) Gas, tetrachlorosilane (SiCl 4) Gas, hexachlorodisilane (Si 2Cl 6) Gas, octachlorotrisilane (Si 3Cl 8) Chlorosilane gas, etc. As the first gas, one or more of these gases can be used. As the first gas, in addition to chlorosilane gas, for example, tetrafluorosilane (SiF 4) Gas, difluorosilane (SiH 2F 2) Gases such as fluorosilane gas or tetrabromosilane (SiBr 4) Gas, dibromosilane (SiH 2Br 2) Gases such as bromosilane gas or tetraiodosilane (SiI 4) Gas, diiodosilane (SiH 2I 2) Iodosilane gas, etc. As the first gas, one or more of these can be used. As the first gas, for example, a gas containing Si as the first element and an alkyl group as R, that is, an alkylsilane-based gas, can be used. The alkyl group is selected from alkanes (formula C n H 2n+2 The general term for the atomic groups remaining after removing one H atom from a chain saturated hydrocarbon represented by the general formula C n H 2n+1 The functional group represented by alkyl includes methyl, ethyl, propyl, butyl, etc. As the first gas, for example, monomethylsilane (SiH 3CH 3) Gas, dimethylsilane (SiH 2(CH 3) 2) Gas, trimethylsilane (SiH(CH 3) 3) Gas, hexamethyldisilane ((CH 3) 3Si 2(CH 3) 3) Gas, monoethylsilane (SiH 3C 2H 5) Gas, triethylsilane (SiH(C 2H 5) 3) Gas, diethylsilane (SiH 2(C 2H 5) 2) Alkylsilane-based gases such as gases. As the first gas, one or more of these gases can be used. The second gas can be a gas containing a compound represented by the formula M2Ry. Here, M2 is the second element, R is a group (also known as a residue, substituent, or ligand), and y is an integer greater than or equal to 1. A gas containing the second element and one or more R atoms bonded to the second element in one molecule can be used. Furthermore, R atoms are selected from hydrogen, an alkyl group, a halogen element, and the like. As the second gas, for example, phosphine (PH) containing phosphorus (P) belonging to Group 15 as the second element and H as R can be used. 3) Gas, diphosphine (P 2H 6) Phosphine-based gases such as phosphine gas. As the second gas, one or more of these can be used. As the second gas, for example, phosphorus trichloride (PCl) containing P, an element belonging to Group 15, as the second element and halogen as R can be used. 3) Gases such as phosphorus halide gases, etc. As the inert gas, for example, nitrogen (N 2), or rare gases such as argon (Ar), helium (He), neon (Ne), and xenon (Xe). As an inert gas, one or more of these can be used. This also applies to the steps described below. By supplying a first gas containing a first element and a second gas containing a second element to the wafer 200 under the above conditions, a film containing the first element and the second element can be formed on the surface of the wafer 200 . Specifically, a film containing the first element doped with the second element can be formed. After a film is formed on the surface of wafer 200, valves 243a to 243d are closed, stopping the supply of the first gas, second gas, and inert gas into processing chamber 201. Then, processing chamber 201 is evacuated to remove (flushed) any remaining gases from the processing chamber 201. At this point, valves 243c and 243d are opened to supply inert gas into processing chamber 201. The inert gas acts as a flushing gas. (Planarization Step: Step B) Thereafter, the following steps B1 and B2 are performed in sequence. [Step B1] In this step, with the wafer 200 having a film formed on its surface housed in the processing chamber 201, the processing chamber 201 is evacuated to reduce the pressure in the processing chamber 201 to a predetermined level. Specifically, with the APC valve 244 at its maximum opening (fully open), the processing chamber 201 is evacuated (vacuum evacuated) using the vacuum pump 246. At this time, valves 243c and 243d remain closed, and no inert gas is supplied to the processing chamber 201. Furthermore, the fully opened valve opening does not necessarily need to be 100%, and a tolerance of -10% is sometimes acceptable. A tolerance of -5% is preferred. A valve opening that includes this tolerance is also referred to as "approximately fully open" or "substantially fully open." The treatment conditions in this step include: Treatment temperature: 300-500°C, preferably 350-450°C Treatment pressure: 0.1-10 Pa, preferably 0.1-5 Pa Vacuuming time: 1-100 minutes The treatment pressure in this step is lower than that in step A. By evacuating the processing chamber 201 , the first gas, the second gas, reaction products, the inert gas, etc. remaining in the processing chamber 201 are removed from the processing chamber 201 , and the processing chamber 201 and at least the surface of the wafer 200 are cleaned. After the vacuuming of the processing chamber 201 is completed, the valve opening of the APC valve 244 is adjusted (reduced) to control the pressure in the processing chamber 201 to a predetermined pressure. After the processing chamber 201 reaches the predetermined pressure, the next step B2 is executed. [Step B2] In this step, an inert gas is supplied to the wafer 200 in the processing chamber 201 . Specifically, valves 243c and 243d are opened to allow inert gas to flow into gas supply pipes 232c and 232d. The inert gas is flow-regulated by MFCs 241c and 241d, supplied into processing chamber 201 via nozzles 249a and 249b, and exhausted from exhaust port 231a. At this time, inert gas is supplied to wafer 200 from the side (inert gas supply). As the processing conditions when supplying inert gas in this step, the following can be cited: Processing temperature: 300~500℃, preferably 350~450℃ Processing pressure: 1~100Pa, preferably 10~30Pa Inert gas supply flow rate (per gas supply pipe): 2~10slm, preferably 3~5slm Inert gas supply time: 1~100 minutes The processing pressure in this step is preferably lower than the processing pressure in step A. By supplying inert gas to the wafer 200 under the above-mentioned processing conditions, the processing chamber 201 is flushed, and the first gas, second gas, and reaction byproducts remaining in the processing chamber 201 are removed from the processing chamber 201, and the environment in the processing chamber 201 is replaced with inert gas. After the flushing of the processing chamber 201 is completed, the valves 243 c and 243 d are closed to stop the supply of the inert gas into the processing chamber 201 . [Implement a predetermined number of times] By performing the above-mentioned steps A and B in sequence non-simultaneously, i.e., non-periodically, for m times (m is an integer greater than or equal to 1 or 2), a film of desired thickness can be formed on the surface of the wafer 200. The above-mentioned cycle is preferably repeated multiple times. That is, it is preferred to repeat the above-mentioned cycle multiple times until the thickness of the film formed in each cycle is thinner than the desired film thickness, and the film thickness of the film formed by the accumulation of the films formed in each cycle becomes the desired film thickness. In addition, in step B performed after step A is implemented, a cycle of steps B1 and B2 is performed in sequence non-simultaneously, i.e., non-synchronously, for n times (n is an integer greater than or equal to 1 or 2) (hereinafter sometimes referred to as a flattening cycle). Thereby, the flatness of the surface of the film formed on the wafer 200 can be improved. Details on the flatness of the surface of the film will be described later. (Purge and Restoration of Atmospheric Pressure) After film formation is completed, an inert gas is supplied from nozzles 249a and 249b into the processing chamber 201 as a purge gas, and the gas is exhausted from exhaust port 231a. This purges the processing chamber 201, removing any remaining gas, reaction byproducts, and the like (purge). The atmosphere in the processing chamber 201 is then replaced with an inert gas (inert gas replacement), and the pressure in the processing chamber 201 is restored to normal pressure (restoration of atmospheric pressure). (Wafer Boat Unloading and Wafer Removal) Afterwards, the sealing cap 219 is lowered by the boat elevator 115, opening the lower end of the manifold 209. The processed wafers 200, supported by the boat 217, are then unloaded from the lower end of the manifold 209 to the exterior of the reaction tube 203 (wafer unloading). After the boat is unloaded, the shutter 219s is moved, sealing the lower end opening of the manifold 209 with the shutter 219s via the O-ring 220c. After being unloaded to the exterior of the reaction tube 203, the processed wafers 200 are removed from the boat 217 (wafer unloading). (3) Effects of this aspect According to this aspect, one or more of the following effects can be obtained. (a) In step B, by improving the flatness of the surface of the film formed on wafer 200, the surface roughness of the film can be improved. This is explained below. Here, surface roughness refers to the height difference of the film within the wafer surface (synonymous with surface roughness), with smaller values ​​indicating a smoother surface. In other words, improving surface roughness means reducing the height difference of the film and improving surface smoothness. In the present invention, the state where the number of R is less than M1Rx is also referred to as M1Ra. a is an integer greater than 1, and has the relationship a<x. In addition, the state where the number of R is less than M2Ry is also referred to as M2Rb. b is an integer greater than 1, and has the relationship b<y. In the following examples, the case where a material in which M1 is Si and R is H and a material in which M2 is P and R is H are used will be described. In this case, M1Rx is SiH 4. M1Ra includes SiH 3. SiH 2. At least one of SiH, etc. M2Ry is PH 3. M2Rb including PH 2. At least one of PH, etc. As described above, step A is performed under conditions where the first gas and the second gas are thermally decomposed. Thus, in step A, at least a portion of the molecular structure of the molecules constituting the first gas and at least a portion of the molecular structure of the molecules constituting the second gas are adsorbed (deposited) on the wafer 200 to form a film. Specifically, for example, when using M1Rx gas as the first gas and M2Ry gas as the second gas, on the wafer 200, the molecules constituting the first gas (M1Rx) and the molecules constituting the second gas (M2Ry) are physically adsorbed, or a portion of the molecular structure of the molecules constituting the first gas (M1Ra) and a portion of the molecular structure of the molecules constituting the second gas (M2Rb) are physically adsorbed or chemically adsorbed, or these are deposited, thereby forming a film containing the first element and the second element. Since M1Ra, M2Rb, etc. are physically adsorbed or chemically adsorbed on the outermost surface of the film formed in this manner, the surface flatness of the film is likely to deteriorate, and the surface roughness may increase. (b) In this embodiment, in step B, at least a portion of the molecules (M1Rx, M1Ra, M2Ry, M2Rb) adsorbed on the outermost surface of the film formed on the wafer 200 is removed. Specifically, in step B2, by supplying an inert gas to the wafer 200, the molecules of the inert gas collide with the molecules (M1Rx, M1Ra, M2Ry, M2Rb) adsorbed on the surface of the film, so that these molecules are detached from the surface of the film. Thereby, the flatness of the surface of the film can be improved, and the surface roughness of the film can be improved. In addition, in step B, at least a portion of the molecules (M1Rx, M1Ra, M2Ry, M2Rb) adsorbed on the outermost surface of the film are removed, and as a result, the number of atoms (first element, second element) constituting the film is reduced, or the number of molecules adsorbed on the surface of the film is reduced. In addition, the molecules adsorbed on the outermost surface of the membrane or the molecules adsorbed on the surface of the membrane referred to in this specification include molecules constituting the first gas (M1Rx), molecules constituting the second gas (M2Ry), a part of the molecular structure of the molecules constituting the first gas (M1Ra), and a part of the molecular structure of the molecules constituting the second gas (M2Rb). (c) In addition, in the present embodiment, in step B, at least the physically adsorbed molecules among the molecules physically adsorbed on the surface of the film and the molecules chemically adsorbed on the surface of the film are removed. Specifically, in step B2, by supplying an inert gas to the wafer 200, the molecules of the inert gas collide with the molecules physically adsorbed on the surface of the film (M1Rx, M1Ra, M2Ry, M2Rb) and the molecules chemically adsorbed on the surface of the film (M1Ra, M2Rb), so that at least the physically adsorbed molecules are detached from the surface of the film. In this way, by detaching the overwhelming majority of the physically adsorbed molecules among the molecules physically adsorbed on the surface of the film and the molecules chemically adsorbed on the surface of the film from the surface of the film, the flatness of the surface of the film can be effectively improved, and the surface roughness of the film can be effectively improved. In addition, by detaching the physically adsorbed molecules with weaker adsorption force (bonding force) to the surface of the wafer 200 among the molecules physically adsorbed on the surface of the film and the molecules chemically adsorbed on the surface of the film from the surface of the film, the flatness of the surface of the film can be effectively improved, and the surface roughness of the film can be effectively improved. In this specification, the term "physical adsorbed molecules" includes molecules that constitute the first gas (M1Rx), molecules that constitute the second gas (M2Ry), a portion of the molecular structure of molecules that constitute the first gas (M1Ra), and a portion of the molecular structure of molecules that constitute the second gas (M2Rb). Furthermore, the term "chemisorbed molecules" refers to a portion of the molecular structure of molecules that constitute the first gas (M1Ra) and a portion of the molecular structure of molecules that constitute the second gas (M2Rb). (d) In addition, in this embodiment, in step B, a portion of the molecules chemically adsorbed on the surface of the film are removed. Specifically, in step B2, by supplying an inert gas to the wafer 200, the molecules of the inert gas collide with the molecules (M1Rx, M1Ra, M2Ry, M2Rb) adsorbed on the surface of the film, so that a portion of the molecules chemically adsorbed on the surface of the film (M1Ra, M2Rb) are detached from the surface of the film. The molecules chemically adsorbed on the surface of the film mentioned here include not only molecules completely chemically adsorbed on the surface of the film, but also molecules that are chemically adsorbed. Moreover, the portion of molecules mentioned here refers to molecules completely chemically adsorbed on the surface of the film, that is, molecules that are not firmly adsorbed on the surface of the film, but molecules that are chemically adsorbed (molecules that are not completely chemically adsorbed), that is, molecules with weak adsorption force (bonding force) on the surface of the film. In this way, by detaching the chemically adsorbed molecules that can be detached from the surface of the film, the flatness of the surface of the film can be effectively improved, and the surface roughness of the film can be effectively improved. (e) Step B includes a step B1 of removing the gas in the processing chamber 201, and a step B2 of supplying an inert gas thereafter. As described above, in step B2, by supplying an inert gas to the wafer 200 in the processing chamber 201, the molecules of the inert gas collide with the molecules (M1Ra, M2Rb, etc.) adsorbed on the surface of the film, so that these molecules are detached from the surface of the film. In step B of this embodiment, step B1 is performed before step B2 is started, and the first gas, the second gas, etc. remaining in the processing chamber 201 are removed from the processing chamber 201, thereby cleaning the processing chamber 201 and at least the surface of the wafer 200 before step B2 is started. Here, cleaning the processing chamber 201 and at least the surface of the wafer 200 refers to reducing the number of molecules (M1Ra, M2Rb, etc.) in the processing chamber 201 and at least on the surface of the wafer 200. Thus, in step B2, the probability of collision between the molecules of the inert gas and the molecules (M1Ra, M2Rb, etc.) adsorbed on the surface of the film can be increased. As a result, the molecules (M1Ra, M2Rb, etc.) adsorbed on the surface of the film are easily detached from the surface of the film. In addition, in step B1, by improving the cleanliness of the processing chamber 201, the re-adsorption of the molecules (M1Ra, M2Rb, etc.) detached from the surface of the film in step B2 to the surface of the wafer 200 can be suppressed. Thus, the flatness of the surface of the film can be effectively improved, and the surface roughness of the film can be effectively improved. (f) The processing pressure in either step B1 or step B2 of step B is lower than the processing pressure in step A. Thus, in step B1, the interior of the processing chamber 201 can be effectively cleaned, and in step B2, the re-adsorption of molecules (M1Ra, M2Rb, etc.) detached from the surface of the film onto the surface of the wafer 200 can be effectively suppressed. (g) In step B1, by fully opening the APC valve 244, the gas remaining in the processing chamber 201 can be effectively removed, thereby cleaning the processing chamber 201. This increases the probability of collision between the inert gas molecules supplied in step B2 and the molecules (M1Ra, M2Rb, etc.) adsorbed on the surface of the film, making it easier for these molecules (M1Ra, M2Rb, etc.) to be released. In addition, it is possible to prevent the M1Ra, M2Rb, etc. that have been released from the surface of the film in step B2 from being re-adsorbed on the surface of the wafer 200. (h) In step B, the valve opening of the APC valve 244 during step B2 is made smaller than the valve opening of the APC valve 244 before step B2. This increases the probability of collision between the molecules of the inert gas supplied in step B2 and the molecules (M1Ra, M2Rb, etc.) adsorbed on the membrane surface. (i) In step B, by performing n times (n is an integer greater than or equal to 1 or 2), especially multiple times, of the planarization cycle including step B1 and step B2, the flatness of the surface of the film can be effectively improved, and the surface roughness of the film can be effectively improved. (j) In this embodiment, in step A, two different gases, a first gas and a second gas, are supplied to the wafer 200 at the same time, so the reaction of the gases tends to become excessive and the flatness of the surface of the film tends to deteriorate. However, according to this embodiment, the deterioration of the flatness of the surface of the film can be suppressed. <Other aspects of the present invention> While aspects of the present invention have been specifically described above, the present invention is not limited to the above-described aspects and can be modified in various ways without departing from the spirit and scope of the present invention. For example, in the above embodiment, the first element contained in the first gas is Si. However, the present invention is not limited to this embodiment. For example, the first element may be Ge (germanium). In this case, for example, germanium (GeH) can be used as the first gas. 4) Gas, digermane (Ge 2H 6) Gas, trigermane (Ge 3H 8) Gas, Tetragermane (Ge 4H 10 ) gas, pentagermane (Ge 5H 12 ) gas, hexagermane (Ge 6H 14 In this embodiment, the same effect as that of the above embodiment can be obtained. For example, in the above embodiment, the second element contained in the second gas is P, which is a Group 15 element. However, the present invention is not limited to this embodiment. For example, the second element may be arsenic (As), which is a Group 15 element, or boron (B), Al (aluminum), gallium (Ga), or In (indium), which are Group 13 elements. In this case, as the second gas, for example, arsine (AsH 3) Gas, monoborane (BH 3) Gas, diborane (B 2H 6) Gas, triborane (B 3H 8) Gas, tetraborane (B 4H 10 ) gas, boron trichloride (BCl 3) Gas, Boron Tetrachloride (B 2Cl 4) Aluminum chloride (AlCl 3) Gallium chloride (GaCl 3) Indium chloride (InCl 3) As the second gas, one or more of the above can be used. In this embodiment, the same effect as the above embodiment can be obtained. Although not specifically described in the above embodiment, a wafer 200 having a recessed portion such as a trench, groove, or hole formed on the surface as a three-dimensional structure may also be used. In this embodiment, the same effects as those of the above embodiment can be obtained. The film formed on the surface within the recessed portion tends to easily form voids or seals during embedding, but in this embodiment, the formation of voids and seals during embedding can be prevented. In the above-mentioned aspect, the case where the supply period of the first gas and the supply period of the second gas in step A completely overlap, that is, the case where the first gas and the second gas are supplied simultaneously is described as an example. However, the present invention is not limited to this aspect. For example, in step A, the first gas and the second gas can be supplied in a manner that the supply period of the first gas and at least a portion of the supply period of the second gas overlap. In this aspect, the same effect as the above-mentioned aspect can also be obtained. In addition, the overlap of the supply period of the first gas and at least a portion of the supply period of the second gas refers to the following supply mode. The following supply mode is performed in step A. Here, "+" means that there is a period in which the gases recorded before and after "+" are supplied simultaneously, and "→" means that they are supplied in sequence rather than simultaneously. When the same gas is recorded before and after "→", it means that the gas is supplied continuously. (1) First gas + second gas (2) First gas + second gas → first gas (3) First gas → first gas + second gas (4) First gas → first gas + second gas → first gas (5) First gas → first gas + second gas → second gas In the above embodiment, the description is made of a case where, in step B, step B1 of removing the gas from the processing chamber 201 is performed, followed by step B2 of supplying an inert gas. However, the present invention is not limited to this embodiment. For example, in step B, step B2 of supplying an inert gas may be performed first, followed by step B1 of removing the gas from the processing chamber 201. In this embodiment, the same effects as those of the above embodiment can be achieved. Although not specifically described in the above embodiment, when the cycle of steps A and B is repeated for a predetermined number of times, it is preferred that the thickness of the film formed in each cycle be set to a thickness of 1 atomic layer (1 to 2 Å), a thickness of 2 atomic layers, a thickness of 5 atomic layers, and a thickness exceeding several atomic layers, and the above cycle be repeated 10 to 150 times until the thickness is finally 100 to 150 Å. In this embodiment, the same effect as in the above embodiment can be obtained. In addition, in this embodiment, in step B2, the molecules (SiH 2. PH 2, etc.) are more effectively detached from the surface of the membrane. In the above-mentioned aspect, although not specifically stated, when performing the cycle of step A and step B non-simultaneously for m times (m is an integer greater than or equal to 1 or 2), it is preferable to change the processing conditions in step B according to the thickness of the film formed in each cycle. This is because if the thickness of the film formed in each cycle is large (thick), the flatness of the surface of the film is easily deteriorated, and if the thickness of the film formed in each cycle is small (thin), there is a tendency that the flatness of the surface of the film is difficult to deteriorate. Therefore, when the thickness T1 of the film formed in each cycle is thinner than the thickness T2 of the film formed in each cycle, it is preferable to shorten the implementation time of step B in each cycle, or reduce the processing pressure in step B, or reduce the supply flow rate of the inert gas supplied in step B1, compared with setting the thickness of the film to T2. In this aspect, the same effect as the above-mentioned aspect can also be obtained. In addition, in this aspect, the flatness of the surface of the film can also be more effectively improved. In the above aspect, although not described in detail, the execution time of step A and the execution time of step B may be longer or shorter than that of step B. In either case, the same effect as that of the above aspect can be achieved. In the above embodiment, a case where a wafer 200 having a predetermined seed film formed on its surface is used is described. However, the present invention is not limited to this embodiment. For example, a wafer 200 without a predetermined seed film formed on its surface may also be used. In this case, it is preferred to perform a step of forming a predetermined seed film on the surface of the wafer 200 before starting step A. In this embodiment, the same effects as those of the above embodiment can also be obtained. In the above embodiment, the first gas and the second gas are supplied in step A. However, the present invention is not limited to this embodiment. For example, the second gas may not be supplied in step A. In this embodiment, the same effects as those in the above embodiment can be achieved. The recipes used in each process are preferably prepared individually based on the process content and recorded and stored in the memory device 121c via an electrical communication line or an external memory device 123. Furthermore, when each process is started, the CPU 121a preferably selects an appropriate recipe from the multiple recipes recorded and stored in the memory device 121c based on the process content. This allows a single substrate processing apparatus to reproducibly form films of various film types, composition ratios, film qualities, and film thicknesses. Furthermore, this reduces the burden on operators, prevents operational errors, and allows each process to be started quickly. The above-mentioned recipes are not limited to newly created ones; for example, they can be prepared by modifying an existing recipe already installed in a substrate processing apparatus. When modifying a recipe, the modified recipe can be installed in the substrate processing apparatus via an electrical communication line or a recording medium containing the recipe. Alternatively, the input / output device 122 of an existing substrate processing apparatus can be used to directly modify an existing recipe installed in the apparatus. In the above-described embodiment, an example of forming a film using a batch-type substrate processing apparatus that processes multiple substrates at a time is described. The present invention is not limited to the above-described embodiment and can also be appropriately applied to forming a film using a single-wafer-type substrate processing apparatus that processes one or more substrates at a time. In addition, in the above-described embodiment, an example of forming a film using a substrate processing apparatus having a hot-wall processing furnace is described. The present invention is not limited to the above-described embodiment and can also be appropriately applied to forming a film using a substrate processing apparatus having a cold-wall processing furnace. Furthermore, in the above aspects, an example is described in which the above processing sequence is performed in the same processing chamber of the same processing apparatus (in-situ). The present invention is not limited to the above aspects. For example, any step and other steps of the above processing sequence may be performed in different processing chambers of different processing apparatuses (ex-situ), or may be performed in different processing chambers of the same processing apparatus. When these substrate processing apparatuses are used, each process can be performed using the same processing procedures and processing conditions as those in the above-described aspects or modifications, and the same effects as those in the above-described aspects or modifications can be obtained. The above-mentioned aspects and modifications can be used in combination as appropriate. The processing procedures and processing conditions in this case can be, for example, the same as those in the above-mentioned aspects or modifications. 115: Wafer boat elevator 115s: Shutter opening and closing mechanism 121: Controller 121a: CPU 121b: RAM 121c: Memory device 121d: I / O port 121e: Internal bus 122: Input / output device 123: External memory device 200: Wafer (substrate) 201: Processing chamber 202: Processing furnace 203: Reaction tube 207: Heater 209: Manifold 217: Wafer boat 218: Heat shield 219: Sealing cover 219s: Shutter 220a, 220b, 220c: O-ring 231: Exhaust pipe 231a: Exhaust port 232a, 232b, 232c, 232d: Gas supply pipe 241a, 241b, 241c, 241d: Mass flow controller (MFC) 243a, 243b, 243c, 243d: Valve 244: APC valve 245: Pressure sensor 246: Vacuum pump 248: Accumulated gas supply system 249a, 249b: Nozzle 250a, 250b: Gas supply hole 255: Rotating shaft 263: Temperature sensor 267: Rotating mechanism FIG1 is a schematic diagram of the configuration of a vertical processing furnace of a substrate processing apparatus used in one embodiment, and shows a portion of the processing furnace 202 in a longitudinal cross-sectional view. FIG2 is a schematic diagram of the configuration of a vertical processing furnace of a substrate processing apparatus used in one embodiment, and shows a portion of the processing furnace 202 in a cross-sectional view taken along line AA of FIG1 . FIG3 is a schematic diagram of the configuration of a controller 121 of a substrate processing apparatus used in one embodiment, and shows a control system of the controller 121 in a block diagram. FIG4 is a diagram showing a processing sequence in one embodiment.

Claims

1. A substrate processing method comprising the steps of: (a) supplying a first gas and a second gas to a substrate to form a film; and (b) improving the flatness of the surface of the film; performing a predetermined number of cycles of performing (a) and (b) non-simultaneously, and changing the processing conditions in (b) according to the thickness of the film formed in each cycle.

2. The substrate processing method as described in claim 1, wherein, The process is carried out under the conditions of thermal decomposition of the first gas and the second gas described above (a).

3. The substrate processing method as described in claim 1, wherein, In (a), the first gas and the second gas are supplied in such a manner that at least a portion of the supply period of the first gas and the supply period of the second gas overlap.

4. The substrate processing method as described in claim 2, wherein, In (a), at least a portion of the molecular structure constituting the molecules of the first gas and at least a portion of the molecular structure constituting the molecules of the second gas are adsorbed onto the surface of the membrane.

5. The substrate processing method as described in claim 4, wherein, In (b), at least the phytoadsorbed molecules among the phytoadsorbed molecules and the chemiadsorbed molecules on the surface of the above membrane are removed.

6. The substrate processing method as described in claim 4, wherein, In (b), a portion of the molecules that are chemically adsorbed on the surface of the above-mentioned membrane are removed.

7. The substrate processing method as described in claim 1, wherein, A recess is formed in the substrate, and the film is formed on the surface of the recess.

8. The substrate processing method as described in claim 1, wherein, In (b), an inert gas is supplied to the membrane.

9. The substrate processing method as described in claim 8, wherein, (b) The system comprises the following steps: (b1) removing the gas from the space where the substrate exists; and (b2) supplying the inert gas thereafter.

10. The substrate processing method as described in claim 9, wherein, In (b), a predetermined number of loops including (b1) and (b2) are performed.

11. A substrate processing method comprising the following steps: (a) supplying a first gas and a second gas to the substrate to form a film; and (b) the step of (b) comprising the following steps: (b1) removing gas from the space in which the substrate exists; and (b2) supplying an inert gas after (b1); when performing (b1), the valve for venting the space is set to a fully open state.

12. The substrate processing method as described in claim 11, wherein, In (b), the opening degree of the valve when (b2) is executed is less than the opening degree before (b2) is executed.

13. A substrate processing method comprising the steps of: (a) supplying a first gas and a second gas to a substrate to form a film; and (b) improving the flatness of the surface of the film; wherein in (b), the number of atoms constituting the film is reduced.

14. The substrate processing method as described in claim 4, wherein, In (b), the number of at least any of the molecules and atoms adsorbed on the surface of the above membrane is reduced.

15. The substrate processing method as described in claim 4, wherein, In (b), at least a portion of the molecules adsorbed on the outermost surface of the above membrane are removed.

16. The substrate processing method as described in claim 1, wherein, When the thickness T1 of the membrane formed in each cycle is thinner than the thickness T2 of the membrane formed in each cycle, the implementation time of (b) in each cycle is shortened compared to when the thickness of the membrane is set to T2.

17. A method for manufacturing a semiconductor device, comprising the steps of: (a) supplying a first gas and a second gas to a substrate to form a film; and (b) improving the flatness of the surface of the film; performing a predetermined number of cycles of performing (a) and (b) non-simultaneously, and changing the processing conditions in (b) according to the thickness of the film formed in each cycle.

18. A program that uses a computer to enable a substrate processing apparatus to perform the following procedures: (a) a procedure for supplying a first gas and a second gas to a substrate to form a film; (b) a procedure for improving the flatness of the surface of the film; and a procedure for performing a predetermined number of cycles of performing (a) and (b) non-simultaneously, and changing the processing conditions in (b) according to the thickness of the film formed in each cycle.

19. A substrate processing apparatus comprising: a first gas supply system for supplying a first gas to a substrate; a second gas supply system for supplying a second gas to the substrate; and a control unit configured to control the first gas supply system and the second gas supply system to perform (a) a process of forming a film by supplying the first gas and the second gas to the substrate, (b) a process of improving the surface flatness of the film, and a process of performing (a) and (b) a predetermined number of cycles that are not performed simultaneously, wherein the processing conditions in (b) are changed according to the thickness of the film formed in each cycle.

20. A method for manufacturing a semiconductor device, comprising the following steps: (a) supplying a first gas and a second gas to a substrate to form a film; and (b) the step of (b); wherein the step of (b) comprises the following steps: (b1) removing gas from the space in which the substrate exists; and (b2) supplying an inert gas after (b1); wherein, when performing (b1), the valve for venting gas from the space is set to a fully open state.

21. A program that uses a computer to enable a substrate processing apparatus to perform the following procedures: (a) a procedure for supplying a first gas and a second gas to a substrate to form a film; (b) a procedure; wherein the (b) procedure includes the following procedures: (b1) a procedure for removing gas from the space in which the substrate exists; and (b2) a procedure for supplying an inert gas after (b1); and a procedure for setting the valve for venting gas from the space to a fully open state when (b1) is executed.

22. A substrate processing apparatus comprising: a first gas supply system for supplying a first gas to a substrate; a second gas supply system for supplying a second gas to the substrate; and a control unit configured to control the first gas supply system and the second gas supply system to perform: (a) a process of forming a film by supplying the first gas and the second gas to the substrate; (b) a process wherein the (b) process comprises: (b1) a process of removing gas from the space in which the substrate exists; and (b2) a process of supplying an inert gas after (b1); and a process of setting the valve for venting gas from the space to a fully open state when (b1) is performed.

23. A method for manufacturing a semiconductor device, comprising the steps of: (a) supplying a first gas and a second gas to a substrate to form a film; and (b) improving the flatness of the surface of the film; wherein in (b), the number of atoms constituting the film is reduced.

24. A program that uses a computer to enable a substrate processing apparatus to perform the following procedures: (a) a procedure for supplying a first gas and a second gas to a substrate to form a film; (b) a procedure for improving the flatness of the surface of the film; and in (b) a procedure for reducing the number of atoms constituting the film.

25. A substrate processing apparatus comprising: a first gas supply system for supplying a first gas to a substrate; a second gas supply system for supplying a second gas to the substrate; and a control unit configured to control the first gas supply system and the second gas supply system to perform: (a) a process of forming a film by supplying the first gas and the second gas to the substrate; (b) a process of improving the flatness of the surface of the film; and in (b) a process of reducing the number of atoms constituting the film.

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