Substrate processing method, method for manufacturing a semiconductor device, substrate processing apparatus, and program

Abstract

The present invention involves performing (a) a step for supplying a first feedstock gas to a substrate where a recessed structure has been provided to a surface thereof, and forming a first film having a prescribed adhesive force on an inner surface of the recessed structure, and (b) a step for supplying a second feedstock gas to the substrate, and forming, on the first film, a second film having a lower adhesive force than the adhesive force of the first film.

Description

Technical Field

[0001] The present disclosure relates to Substrate processing method, a method for manufacturing a semiconductor device, a substrate processing apparatus, and a program.

Background Art

[0002] As one step in the manufacturing process of a semiconductor device, a process of forming a film on the surface of a substrate may be performed (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present disclosure is to provide a technique for reducing stress generated between patterns formed on the surface of a substrate when embedding the inside of a concave structure of the substrate with a film.

Means for Solving the Problems

[0005] According to one aspect of the present disclosure, (a) supplying a first source gas to a substrate provided with a concave structure on the surface, and forming a first film having a predetermined adhesion force on the inner surface of the concave structure; (b) supplying a second source gas to the substrate, and forming a second film having an adhesion force smaller than that of the first film on the first film; and a technique for performing the above is provided.

Effects of the Invention

[0006] According to the present disclosure, when embedding the inside of the concave structure of the substrate with a film, it is possible to reduce the stress generated between the patterns formed on the surface of the substrate.

Brief Description of the Drawings

[0007]

Figure 1

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Figure 3

Figure 4

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Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0008] <One Aspect of the Present Disclosure> Hereinafter, one aspect of the present disclosure will be mainly described with reference to FIGS. 1 to 4. Note that the drawings used in the following description are all schematic, and the dimensional relationships and ratios of the respective elements shown in the drawings do not necessarily match the actual ones. Also, the dimensional relationships and ratios of the respective elements do not necessarily match between the plurality of drawings.

[0009] (1) Configuration of Substrate Processing Apparatus As shown in FIG. 1, the processing furnace 202 has a heater 207 as a temperature adjuster (heating unit). The heater 207 has a cylindrical shape and is vertically installed by being supported by a holding plate. The heater 207 also functions as an activation mechanism (excitation unit) for activating (exciting) gas with heat.

[0010] Inside the heater 207, a reaction tube 203 is arranged concentrically with the heater 207. The reaction tube 203 is made of, for example, quartz (SiO 2It is made of a heat-resistant material such as silicon carbide (SiC) and is formed in a cylindrical shape with the upper end closed and the lower end open. Below the reaction tube 203, a manifold 209 is arranged concentrically with the reaction tube 203. The manifold 209 is made of a metal material such as stainless steel (SUS) for example, and is formed in a cylindrical shape with the upper and lower ends open. The upper end portion of the manifold 209 is engaged with the lower end portion of the reaction tube 203 and is configured to support the reaction tube 203. An O-ring 220a as a seal member is provided between the manifold 209 and the reaction tube 203. The reaction tube 203 is installed vertically in the same way as the heater 207. Mainly, the reaction tube 203 and the manifold 209 constitute a processing container (reaction container). A processing chamber 201 is formed in the cylindrical hollow portion of the processing container. The processing chamber 201 is configured to be able to accommodate a wafer 200 as a substrate. Processing of the wafer 200 is performed in this processing chamber 201.

[0011] In the processing chamber 201, nozzles 249a and 249b as a first supply unit and a second supply unit are respectively provided so as to penetrate the side wall of the manifold 209. The nozzles 249a and 249b are also respectively referred to as a first nozzle and a second nozzle. The nozzles 249a and 249b are made of a heat-resistant material such as quartz or SiC for example. Gas supply pipes 232a and 232b are respectively connected to the nozzles 249a and 249b. The nozzles 249a and 249b are different nozzles and are provided adjacent to each other.

[0012] In the gas supply pipes 232a and 232b, a mass flow controller (MFC) 241a and 241b, which are flow rate controllers (flow rate control units), and valves 243a and 243b, which are on-off valves, are respectively provided in order from the upstream side of the gas flow. On the downstream side of the valve 243a in the gas supply pipe 232a, the gas supply pipes 232c to 232e are respectively connected. On the downstream side of the valve 243b in the gas supply pipe 232b, the gas supply pipe 232f is connected. In the gas supply pipes 232c to 232f, an MFC 241c to 241f and valves 243c to 243f are respectively provided in order from the upstream side of the gas flow. The gas supply pipes 232a to 232f are made of a metal material such as SUS, for example.

[0013] As shown in FIG. 2, the nozzles 249a and 249b are respectively provided in an annular space in a plan view between the inner wall of the reaction tube 203 and the wafer 200, along the upper part from the lower part of the inner wall of the reaction tube 203, so as to rise upward in the arrangement direction of the wafers 200. That is, the nozzles 249a and 249b are respectively provided in a region on the side of the wafer arrangement region where the wafers 200 are arranged, in a region that horizontally surrounds the wafer arrangement region, along the wafer arrangement region. Gas supply holes 250a and 250b for supplying gas are respectively provided on the side surfaces of the nozzles 249a and 249b. The gas supply holes 250a and 250b are respectively open toward the center of the wafer 200 in a plan view, and it is possible to supply gas toward the wafer 200. A plurality of gas supply holes 250a and 250b are provided from the lower part to the upper part of the reaction tube 203.

[0014] The first source gas is supplied from the gas supply pipe 232a into the processing chamber 201 through the MFC 241a, the valve 243a, and the nozzle 249a.

[0015] An oxygen (O)-containing gas as an oxidizing gas is supplied from the gas supply pipe 232b into the processing chamber 201 through the MFC 241b, the valve 243b, and the nozzle 249b.

[0016] From the gas supply pipe 232c, the second raw material gas is supplied into the processing chamber 201 via the MFC241c, the valve 243c, and the nozzle 249a.

[0017] From the gas supply pipe 232d, a hydrogen (H)-containing gas as a reducing gas is supplied into the processing chamber 201 via the MFC241d, the valve 243d, the gas supply pipe 232a, and the nozzle 249a. Although the H-containing gas alone cannot obtain an oxidation effect, in the substrate processing step described later, by reacting with an O-containing gas under specific conditions, oxidation species such as atomic oxygen (O) are generated, and it acts to improve the efficiency of the oxidation treatment. Therefore, the H-containing gas can be considered as included in the oxidation gas.

[0018] From the gas supply pipes 232e and 232f, an inert gas is supplied into the processing chamber 201 via the MFC241e and 241f, the valves 243e and 243f, the gas supply pipes 232a and 232b, and the nozzles 249a and 249b, respectively. The inert gas acts as a purge gas, a carrier gas, a dilution gas, etc.

[0019] Primarily, the first raw material gas supply system is constituted by the gas supply pipe 232a, the MFC241a, and the valve 243a. Primarily, the second raw material gas supply system is constituted by the gas supply pipe 232c, the MFC241c, and the valve 243c.

[0020] Primarily, the oxidation gas supply system is constituted by the gas supply pipe 232b, MFC 241b, and valve 243b. Primarily, the reduction gas supply system is constituted by the gas supply pipe 232d, MFC 241d, and valve 243d. The gas supply pipe 232d, MFC 241d, and valve 243d may be considered as included in the oxidation gas supply system. The oxidation gas and the reduction gas are used as reaction gases in the substrate processing step described later. In the substrate processing step, the reaction gas used when forming the first film on the substrate is referred to as the first reaction gas, and the reaction gas used when forming the second film on the substrate can be referred to as the second reaction gas. Therefore, each or both of the oxidation gas supply system and the reduction gas supply system can also be referred to as the reaction gas supply system (the first reaction gas supply system, the second reaction gas supply system).

[0021] Primarily, the inert gas supply system is constituted by the gas supply pipes 232e, 232f, MFCs 241e, 241f, and valves 243e, 243f.

[0022] Each or both of the source gas and the reaction gas are also referred to as the film-forming gas, and each or both of the source gas supply system and the oxidation gas supply system are also referred to as the film-forming gas supply system.

[0023] Among the various supply systems described above, any one, or all of the supply systems may be configured as an integrated supply system 248 in which valves 243a to 243f, MFCs 241a to 241f, etc. are integrated. The integrated supply system 248 is connected to each of the gas supply pipes 232a to 232f, and the supply operation of various substances (various gases) into the gas supply pipes 232a to 232f, that is, the opening and closing operations of the valves 243a to 243f and the flow rate adjustment operations by the MFCs 241a to 241f, etc. are configured to be controlled by the controller 121 described later. The integrated supply system 248 is configured as an integrated unit of an integral type or a split type, and can be attached and detached in units of the integrated unit to the gas supply pipes 232a to 232f, etc., and the maintenance, replacement, addition, etc. of the integrated supply system 248 can be performed in units of the integrated unit.

[0024] Below the lower part of the side wall of the reaction tube 203, an exhaust port 231a for exhausting the atmosphere in the processing chamber 201 is provided. The exhaust port 231a may be provided along the upper part from the lower part of the side wall of the reaction tube 203, that is, along the wafer arrangement area. An exhaust pipe 231 is connected to the exhaust port 231a. A pressure sensor 245 as a pressure detector (pressure detection unit) for detecting the pressure in the processing chamber 201 and an APC (Auto Pressure Controller) valve 244 as a pressure regulator (pressure regulation unit) are interposed in the exhaust pipe 231, and a vacuum pump 246 as a vacuum exhaust device is connected. The APC valve 244 can perform vacuum exhaust and stop of vacuum exhaust in the processing chamber 201 by opening and closing the valve in a state where the vacuum pump 246 is operated. Further, in a state where the vacuum pump 246 is operated, 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. Mainly, the exhaust system is constituted by the exhaust pipe 231, the APC valve 244, and the pressure sensor 245. The vacuum pump 246 may be considered to be included in the exhaust system.

[0025] Below the manifold 209, a seal cap 219 as a furnace port lid body capable of hermetically closing the lower end opening of the manifold 209 is provided. The seal cap 219 is made of a metal material such as SUS, for example, and is formed in a disk shape. An O-ring 220b as a seal member that abuts against the lower end of the manifold 209 is provided on the upper surface of the seal cap 219. Below the seal cap 219, a rotation mechanism 267 for rotating a boat 217 described later is installed. The rotation shaft 255 of the rotation mechanism 267 penetrates the seal cap 219 and is connected to the boat 217. The rotation mechanism 267 is configured to rotate the wafer 200 by rotating the boat 217. The seal cap 219 is configured to be vertically moved up and down by a boat elevator 115 as an elevating mechanism installed outside the reaction tube 203. The boat elevator 115 is configured as a transfer device (transfer mechanism) for loading and unloading (transferring) the wafer 200 into and out of the processing chamber 201 by moving the seal cap 219 up and down.

[0026] Below the manifold 209, there is provided a shutter 219s as a furnace lid that can airtightly close the lower end opening of the manifold 209 with the seal cap 219 lowered and the boat 217 carried out from the processing chamber 201. The shutter 219s is made of a metal material such as SUS, for example, and is formed in a disc shape. An O-ring 220c as a seal member that contacts the lower end of the manifold 209 is provided on the upper surface of the shutter 219s. The opening and closing operation (lifting and lowering operation, rotation operation, etc.) of the shutter 219s is controlled by a shutter opening and closing mechanism 115s.

[0027] The boat 217 as a substrate support is configured to support a plurality of, for example, 25 to 200 wafers 200 in a horizontal posture and vertically aligned with their centers aligned with each other in multiple stages, that is, arranged at intervals. The boat 217 is made of a heat-resistant material such as quartz or SiC, for example. Below the boat 217, heat insulating plates 218 made of a heat-resistant material such as quartz or SiC are supported in multiple stages.

[0028] Inside the reaction tube 203, a temperature sensor 263 as a temperature detector is installed. By adjusting the power supply to the heater 207 based on the temperature information detected by the temperature sensor 263, the temperature in the processing chamber 201 becomes a desired temperature distribution. The temperature sensor 263 is provided along the inner wall of the reaction tube 203.

[0029] As shown in FIG. 3, the controller 121, which is a control unit (control means), is configured as a computer including a CPU (Central Processing Unit) 121a, a RAM (Random Access Memory) 121b, a storage device 121c, and an I / O port 121d. The RAM 121b, the storage 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, for example, a touch panel or the like is connected to the controller 121. Further, an external storage device 123 can be connected to the controller 121.

[0030] The storage device 121c is composed of, for example, a flash memory, an HDD (Hard Disk Drive), an SSD (Solid State Drive), or the like. In the storage device 121c, a control program for controlling the operation of the substrate processing apparatus, a process recipe in which procedures and conditions for substrate processing described later are described, and the like are stored in a readable manner. The process recipe is a combination of procedures in the substrate processing described later that can be executed by the controller 121 on the substrate processing apparatus to obtain a predetermined result, and functions as a program. Hereinafter, the process recipe, the control program, and the like are collectively referred to simply as a program. Further, the process recipe is also simply referred to as a recipe. When the term "program" is used in this specification, 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 (work area) that temporarily holds programs, data, and the like read by the CPU 121a.

[0031] The I / O port 121d is connected to the above-described MFCs 241a to 241f, valves 243a to 243f, pressure sensor 245, APC valve 244, vacuum pump 246, temperature sensor 263, heater 207, rotation mechanism 267, boat elevator 115, shutter opening / closing mechanism 115s, and the like.

[0032] The CPU 121a is configured to read and execute a control program from the storage device 121c, and to be able to read a recipe from the storage device 121c in response to an input of an operation command from the input / output device 122 or the like. The CPU 121a is configured to control the flow rate adjustment operations of various substances (various gases) by the MFCs 241a to 241f, the opening and closing operations of the valves 243a to 243f, the opening and closing operation of the APC valve 244, the pressure adjustment operation by 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 operations of the boat 217 by the rotation mechanism 267, the lifting and lowering operations of the boat 217 by the boat elevator 115, the opening and closing operations of the shutter 219s by the shutter opening and closing mechanism 115s, etc., so as to conform to the content of the read recipe.

[0033] The controller 121 can be configured by installing the above-described program stored in the external storage device 123 on a computer. The external storage device 123 includes, for example, magnetic disks such as HDDs, optical disks such as CDs, magneto-optical disks such as MOs, semiconductor memories such as USB memories and SSDs, and the like. The storage device 121c and the external storage device 123 are configured as computer-readable recording media. Hereinafter, these are collectively referred to simply as recording media. When the term "recording medium" is used in this specification, it may include only the storage device 121c alone, only the external storage device 123 alone, or both of them. Note that the program may be provided to the computer without using the external storage device 123, but by using communication means such as the Internet or a dedicated line.

[0034] (2) Substrate processing step Using the above-described substrate processing apparatus, as one step of the semiconductor device manufacturing process, a processing sequence example of forming a film inside a concave structure so as to fill a concave structure provided on the surface of the wafer 200 as a substrate will be mainly described with reference to FIG. 4. In the following description, the operations of each part constituting the substrate processing apparatus are controlled by the controller 121.

[0035] The inner surface of the concave structure provided on the surface of the wafer 200 has an opposing side surface and a bottom surface. The concave structure is configured in a so-called tapered shape in which the distance between the side surfaces at the lower part of the concave structure is shorter (narrower) than the distance between the side surfaces at the upper part of the concave structure.

[0036] The processing sequence shown in FIG. 4 Step A of supplying a first source gas to the wafer 200 having a concave structure on its surface and forming a first film having a predetermined adhesion force on the inner surface of the concave structure; Step B of supplying a second source gas to the wafer 200 and forming a second film having an adhesion force smaller than that of the first film on the first film.

[0037] In step A, A cycle of non-simultaneously performing a step of supplying the first source gas and a step of supplying the first reaction gas is performed a predetermined number of times (m times, where m is an integer of 1 or more).

[0038] In step B, A cycle of non-simultaneously performing a step of supplying the second source gas and a step of supplying the second reaction gas is performed a predetermined number of times (n times, where n is an integer of 1 or more).

[0039] In this specification, the above-described processing sequence may be shown as follows for convenience. The same notation will be used in the following description of modified examples and other aspects.

[0040] (First source gas → First reaction gas) × m → (Second source gas → Second reaction gas) × n

[0041] When the term "wafer" is used in this specification, it may mean the wafer itself or a laminate of the wafer and a predetermined layer or film formed on its surface. When the term "surface of the wafer" is used in this specification, it may mean the surface of the wafer itself or the surface of a predetermined layer or the like formed on the wafer. When it is described in this specification that "a predetermined layer is formed on the wafer", it may mean directly forming a predetermined layer on the surface of the wafer itself or forming a predetermined layer on a layer or the like formed on the wafer. When the term "substrate" is used in this specification, it is synonymous with the case when the term "wafer" is used.

[0042] (Wafer Charge and Boat Load) When a plurality of wafers 200 are loaded (wafer charge) into the boat 217, the shutter 219s is moved by the shutter opening / closing mechanism 115s, and the lower end opening of the manifold 209 is opened (shutter open). Then, as shown in FIG. 1, the boat 217 supporting the plurality of wafers 200 is lifted by the boat elevator 115 and carried into the processing chamber 201 (boat load). In this state, the seal cap 219 seals the lower end of the manifold 209 via the O-ring 220b.

[0043] (Pressure Adjustment and Temperature Adjustment) Inside the processing chamber 201, that is, the space where the wafer 200 is located is evacuated (depressurized and evacuated) by the vacuum pump 246 so as to reach a desired pressure (degree of vacuum). At this time, the pressure inside 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. Also, the wafer 200 inside the processing chamber 201 is heated by the heater 207 so as to reach a desired processing temperature. At this time, the energization condition of the heater 207 is feedback-controlled based on the temperature information detected by the temperature sensor 263 so that the inside of the processing chamber 201 has a desired temperature distribution. Also, the rotation of the wafer 200 by the rotation mechanism 267 is started. The evacuation inside the processing chamber 201, the heating of the wafer 200, and the rotation are all continuously performed at least until the processing of the wafer 200 is completed.

[0044] (OH terminal formation) In this step, a first reaction gas is supplied (pre-flow) to the wafer 200 inside the processing chamber 201.

[0045] Specifically, the valve 243b is opened, and the first reaction gas is flowed into the gas supply pipe 232b. The first reaction gas is flow-rate adjusted by the MFC241b, supplied into the processing chamber 201 through the nozzle 249b, and exhausted from the exhaust port 231a. At this time, the first reaction gas is supplied to the wafer 200 (reaction gas supply). At this time, the valves 243e and 243f are opened, and an inert gas is supplied into the processing chamber 201 through each of the nozzles 249a and 249b. Note that the supply of the inert gas may not be performed.

[0046] The processing conditions in this step are as follows: Processing temperature: 400 - 900 °C, preferably 600 - 700 °C Processing pressure: 0.1 - 30 Torr, preferably 0.2 - 20 Torr First reaction gas supply flow rate: 0.1 - 20 slm, preferably 5 - 12 slm First reaction gas supply time: 100 - 1000 seconds, preferably 200 - 1000 seconds Inert gas supply flow rate (per gas supply pipe): 0 - 3.0 slm is exemplified.

[0047] Note that the notation of a numerical range such as "400 to 900 °C" in this specification means that the lower limit value and the upper limit value are included in that range. Thus, for example, "400 to 900 °C" means "400 °C or higher and 900 °C or lower". The same applies to other numerical ranges. Also, the processing temperature in this specification means the temperature of the wafer 200 or the temperature inside the processing chamber 201, and the processing pressure means the pressure inside the processing chamber 201. Also, a gas supply flow rate of 0 slm means a case where the gas is not supplied. These are the same in the following description.

[0048] By performing this step under the above-described processing conditions, hydroxyl terminations (OH terminations) can be formed over the entire surface of the wafer 200. The OH terminations present on the surface of the wafer 200 function as adsorption sites for the source gas, that is, adsorption sites for molecules and atoms constituting the source gas, in the film formation process described later.

[0049] After the OH terminations are formed, the valve 243b is closed to stop the supply of the first reaction gas into the processing chamber 201. Then, the inside of the processing chamber 201 is evacuated to remove gaseous substances and the like remaining inside the processing chamber 201 from the processing chamber 201. At this time, the valves 243e and 243f are opened, and an inert gas is supplied into the processing chamber 201 through the nozzles 249a and 249b. The inert gas supplied from the nozzles 249a and 249b acts as a purge gas, whereby the inside of the processing chamber 201 is purged (purging).

[0050] The processing conditions for purging are as follows: Inert gas supply flow rate (per gas supply pipe): 0.5 to 10 slm Inert gas supply time: 1 to 30 seconds, preferably 5 to 20 seconds is exemplified.

[0051] As the inert gas, nitrogen (N 2)Gases and noble gases such as argon (Ar) gas, helium (He) gas, neon (Ne) gas, and xenon (Xe) gas can be used. As the inert gas, one or more of these can be used. This also applies to each step described later.

[0052] (Step A: First film formation) After that, the following steps a1 and a2 are sequentially executed.

[0053] [Step a1] In this step, the first raw material gas is supplied to the wafer 200 in the processing chamber 201.

[0054] Specifically, the valve 243a is opened, and the first raw material gas is flowed into the gas supply pipe 232a. The first raw material gas is adjusted in flow rate by the MFC241a, supplied into the processing chamber 201 through the nozzle 249a, and exhausted from the exhaust port 231a. At this time, the first raw material gas is supplied to the wafer 200 (raw material gas supply). At this time, the valves 243e and 243f are opened, and the inert gas is supplied into the processing chamber 201 through each of the nozzles 249a and 249b. Note that the supply of the inert gas may not be performed.

[0055] The processing conditions in this step are as follows: Processing temperature: 400 - 900 °C, preferably 600 - 700 °C Processing pressure: 0.1 - 10 Torr, preferably 0.2 - 10 Torr First raw material gas supply flow rate: 0.01 - 1 slm, preferably 0.1 - 0.5 slm First raw material gas supply time: 1 - 100 seconds, preferably 15 - 20 seconds Inert gas supply flow rate (per gas supply pipe): 0 - 10.0 slm are exemplified.

[0056] Under the above processing conditions, by supplying, for example, a silane gas containing an amino group and an alkoxy group described later as the first raw material gas to the wafer 200, it becomes possible to desorb the amino group from the silicon (Si) contained in the first raw material gas without desorbing the alkoxy group. Further, it becomes possible to adsorb (chemisorb) Si in a state where the amino group has desorbed and the bond with the alkoxy group is maintained on the surface of the wafer 200. That is, it becomes possible to adsorb Si in a state where alkoxy groups are bonded to three bonding hands of Si to a part of the adsorption sites on the surface of the wafer 200. In this way, it becomes possible to form a first layer (Si-containing layer) containing a component in which an alkoxy group is bonded to Si on the outermost surface of the wafer 200.

[0057] Further, by performing this step under the above processing conditions, it becomes possible to prevent the amino group desorbed from Si contained in the first raw material gas from being adsorbed on the surface of the wafer 200. As a result, it becomes possible to prevent the first layer formed on the wafer 200 from containing the amino group desorbed from Si contained in the first raw material gas. That is, it becomes possible to make the first layer formed on the wafer 200 a layer with a low amino group content and few impurities derived from the amino group, such as impurities such as carbon (C) and nitrogen (N).

[0058] In this step, by using the alkoxy group bonded to Si adsorbed on the surface of the wafer 200, that is, by filling (blocking) the bonding hands of Si adsorbed on the surface of the wafer 200 with alkoxy groups, it becomes possible to inhibit the adsorption of at least any one of atoms or molecules to Si adsorbed on the surface of the wafer 200. Further, in this step, by causing the alkoxy group bonded to Si adsorbed on the surface of the wafer 200 to act as a steric hindrance, it becomes possible to inhibit the adsorption of at least any one of atoms or molecules to the adsorption sites (OH terminals) on the surface of the wafer 200 around Si adsorbed on the surface of the wafer 200. Further, thereby, in this step, it becomes possible to hold the adsorption sites (OH terminals) on the surface of the wafer 200 around Si adsorbed on the surface of the wafer 200.

[0059] In this step, it is preferable to continue supplying the first source gas until the adsorption reaction (chemisorption reaction) on the surface of the Si wafer 200 reaches saturation. Even if the supply of the first source gas is continued in this way, due to the steric hindrance of the alkoxy groups bonded to Si, it becomes possible to adsorb Si discontinuously on the surface of the wafer 200. Specifically, it becomes possible to adsorb Si on the surface of the wafer 200 to a thickness of less than one atomic layer.

[0060] In a state where the adsorption reaction on the surface of the Si wafer 200 has reached saturation, the surface of the wafer 200 is covered with alkoxy groups bonded to Si, and a part of the surface of the wafer 200 is maintained in a state where the adsorption sites (OH terminations) are not consumed. In a state where the adsorption reaction on the surface of the Si wafer 200 has reached saturation, the layer composed of Si adsorbed on the surface of the wafer 200 becomes a discontinuous layer with a thickness of less than one atomic layer.

[0061] After the first layer is formed, close the valve 243a and stop supplying the first source gas into the processing chamber 201. Then, perform the same processing procedure and processing conditions as in the purge for OH termination formation to remove the gas remaining in the processing chamber 201 from the processing chamber 201 (purge).

[0062] As the first source gas, for example, a gas having a molecular structure in which an alkoxy group and an amino group are bonded to Si, which is the main element constituting the film formed on the wafer 200, can be used.

[0063] An alkoxy group has a structure in which an alkyl group (R) is bonded to an oxygen (O) atom, and is a monovalent functional group represented by the structural formula -OR. The alkoxy group (-OR) includes a methoxy group (-OMe), an ethoxy group (-OEt), a propoxy group (-OPr), a butoxy group (-OBu), etc. The alkoxy group may be not only these linear alkoxy groups, but also branched alkoxy groups such as an isopropoxy group, an isobutoxy group, a secondary butoxy group, and a tertiary butoxy group. Further, the alkyl group (-R) includes a methyl group (-Me), an ethyl group (-Et), a propyl group (-Pr), a butyl group (-Bu), etc. The alkyl group may be not only these linear alkyl groups, but also branched alkyl groups such as an isopropyl group, an isobutyl group, a secondary butyl group, and a tertiary butyl group.

[0064] An amino group has a structure in which hydrogen (H) is removed from ammonia (NH 3 ), a primary amine, or a secondary amine, and is a monovalent functional group represented by any of the structural formulas -NH 2 , -NHR, or -NRR'. R and R' shown in the structural formula are alkyl groups including a methyl group, an ethyl group, a propyl group, a butyl group, etc. R and R' may be not only these linear alkyl groups, but also branched alkyl groups such as an isopropyl group, an isobutyl group, a secondary butyl group, and a tertiary butyl group. R and R' may be the same alkyl group or different alkyl groups. Examples of the amino group include a dimethylamino group (-N(CH 3 ) 2 ), a diethylamino group (-N(C 2 H 5 ) 2 ), etc.

[0065] Examples of the first raw material gas include (dimethylamino)triethoxysilane ([(CH 3 ) 2 N]Si(OC 2 H 5 ) 3 ) gas, (diethylamino)triethoxysilane ([(C 2H 5 ) 2 N]Si(OC 2 H 5 ) 3 ) gas, (dimethylamino)trimethoxysilane ([(CH 3 ) 2 N]Si(OCH 3 ) 3 ) gas, (diethylamino)trimethoxysilane ([(C 2 H 5 ) 2 N]Si(OCH 3 ) 3 ) gas and the like of dialkylaminotrialkoxysilane gas can be used. The dialkylaminotrialkoxysilane gas can be used as a silane gas containing an amino group and an alkoxy group. Si contained in these gases has four bonds, and alkoxy groups (methoxy group, ethoxy group) are bonded to three of the four bonds of Si, and an amino group (dimethylamino group, diethylamino group) is bonded to the remaining one of the four bonds of Si. Thus, as the first raw material gas, it is preferable to use an organic gas containing an amino group in the molecular structure. As the first raw material gas, one or more of these can be used.

[0066] As the first raw material gas, for example, tetrakis(dimethylamino)silane (Si[N(CH 3 ) 2 4 , abbreviation: 4DMAS) gas, tris(dimethylamino)silane (Si[N(CH 3 ) 2 3 H, abbreviation: 3DMAS) gas, bis(diethylamino)silane (Si[N(C 2 H 5 ) 2 2 H 2 , abbreviation: BDEAS) gas, bis(tert-butylamino)silane (SiH 2 [NH(C 4 H 9 )] 2 , abbreviation: BTBAS) gas, (diisopropylamino)silane (SiH​​​3 [N(C 3 H 7 ) 2 , abbreviation: DIPAS), etc., and an amino silane-based gas can also be used. As the first raw material gas, one or more of these can be used.

[0067] [Step a2] In this step, an O-containing gas is supplied to the wafer 200 in the processing chamber 201 as the first reaction gas.

[0068] Specifically, the valve 243b is opened, and the first reaction gas is flowed into the gas supply pipe 232b. The flow rate of the first reaction gas is adjusted by the MFC241b, supplied into the processing chamber 201 through the nozzle 249b, and exhausted from the exhaust port 231a. At this time, the first reaction gas is supplied to the wafer 200 (reaction gas supply). At this time, the valves 243e and 243f are opened, and an inert gas is supplied into the processing chamber 201 through each of the nozzles 249a and 249b. Note that the supply of the inert gas may not be performed.

[0069] The processing conditions in this step are as follows: Processing pressure: 0.1 to 30 Torr, preferably 0.2 to 20 Torr First reaction gas supply flow rate: 0.1 to 20 slm, preferably 5 to 12 slm First reaction gas supply time: 1 to 200 seconds, preferably 150 to 190 seconds Inert gas supply flow rate (per gas supply pipe): 0 to 3.0 slm are exemplified. Other processing conditions can be the same as the processing conditions when the first raw material gas supply in step a1 is performed.

[0070] By performing this step under the above-described processing conditions, for example, it becomes possible to desorb the alkoxy group that binds to Si contained in the first layer from the first layer. By supplying, for example, an oxidation gas (O-containing gas) as the first reaction gas to the wafer 200 under the above-described processing conditions, at least a part of the first layer formed on the wafer 200 is oxidized (modified), and as the second layer, a silicon oxide layer (SiO layer) containing Si and O can be formed. The second layer is a layer that does not contain an alkoxy group or the like, that is, a layer that does not contain impurities such as C. Further, as a result of the oxidation treatment with the O-containing gas, the surface of the second layer is in a state terminated with OH, that is, a state in which adsorption sites are formed. Incidentally, impurities such as C desorbed from the first layer constitute gaseous substances such as carbon dioxide (CO 2 ) and are discharged from the inside of the processing chamber 201. Thereby, the second layer (SiO layer) becomes a layer with fewer impurities such as C than the first layer (Si-containing layer) formed in step a1.

[0071] After the second layer is formed, the valve 243b is closed and the supply of the first reaction gas into the processing chamber 201 is stopped. Then, in the same processing procedure and processing conditions as the purge in step a1, the gas and the like remaining in the processing chamber 201 are removed from the processing chamber 201 (purge).

[0072] As the first reaction gas, for example, oxygen (O 2 ) gas, ozone (O 3 ) gas, water vapor (H 2 O gas), hydrogen peroxide (H 2 O 2 ) gas, nitric oxide (NO) gas, nitrous oxide (N 2 O) gas, carbon monoxide (CO) gas, nitrogen dioxide (NO 2 ) gas, plasma-excited O 2 gas (O 2 * ) and other O-containing gases can be used. As the first reaction gas, one or more of these can be used.

[0073] [Performed a predetermined number of times] By performing the above steps a1 and a2 non-simultaneously, that is, without synchronization, for a predetermined number of cycles (m times, where m is an integer of 1 or more), it becomes possible to form a first SiO film as a first film with a predetermined composition and a predetermined film thickness on the wafer 200. It is preferable to repeat the above cycle a plurality of times. That is, the thickness of the second layer (SiO layer) formed by performing the above cycle once is made smaller than the desired film thickness, and it is preferable to repeat the above cycle a plurality of times until the film thickness of the first SiO film formed by laminating the second layer becomes the desired film thickness.

[0074] In step A, it is preferable to form the first SiO film while maintaining a state (film thickness) in which the first SiO films formed on the opposing side surfaces in the concave structure provided on the surface of the wafer 200 do not contact each other.

[0075] Also, in step A, it is preferable that the ratio of the thickness of the first SiO film to the total thickness of the thickness of the first SiO film and the thickness of the second SiO film as the second film described later is 50% or less.

[0076] Also, in step A, it is preferable that the ratio of the thickness of the first SiO film to the total thickness of the thickness of the first SiO film and the thickness of the second SiO film as the second film described later is 10% or more.

[0077] Note that the step coverage of the first SiO film is higher than that of the second SiO film as the second film described later. This is because in step a1, as described above, in a state where the adsorption reaction of Si contained in the first source gas to the surface of the wafer 200 is saturated, the layer composed of Si adsorbed on the surface of the wafer 200 can be made into a discontinuous layer with a thickness of less than one atomic layer. That is, in step a1, for example, regardless of whether it is the side surface near the upper part in the concave structure of the wafer 200 or the bottom of the concave structure, the formation of the first layer with a non-uniform thickness of one atomic layer or more is suppressed, and the first layer is formed as a layer with a uniform thickness excellent in step coverage. In this case, in step a2, for example, the O-containing gas can react with the first layer excellent in step coverage on the side surface near the upper part in the concave structure of the wafer 200 and also at the bottom of the concave structure. As a result, it becomes possible to make the first SiO film a film excellent in step coverage.

[0078] In addition, the first SiO film has the characteristic of being able to maintain the underlying oxidation amount in a better state than the second SiO film as the second film described later. The reason why the underlying oxidation amount can be maintained in a better state when forming the first SiO film than when forming the second SiO film is that in step a2, the first layer is oxidized under processing conditions where the oxidizing power is weaker than that in step b2 described later. Specifically, in step a2, as the first reaction gas, a gas with weaker oxidizing power than the second reaction gas used in step b2 described later is used. As a result, it becomes possible to sufficiently suppress the oxidation of the underlying layer, that is, the oxidation of the surface of the wafer 200 in contact with the first SiO film. By suppressing the oxidation of the surface of the wafer 200, it is possible to reduce the influence such as the deterioration of device characteristics associated therewith.

[0079] (Step B: Second film formation) Thereafter, the following steps b1 and b2 are sequentially executed.

[0080] [Step b1] In this step, the second source gas is supplied to the wafer 200 in the processing chamber 201.

[0081] Specifically, valve 243c is opened, and the second raw material gas is flowed into gas supply pipe 232c. The flow rate of the second raw material gas is adjusted by MFC241c, supplied into processing chamber 201 through nozzle 249a, and exhausted from exhaust port 231a. At this time, the second raw material gas is supplied to wafer 200 (raw material gas supply). At this time, valves 243e and 243f are opened, and an inert gas is supplied into processing chamber 201 through each of nozzles 249a and 249b. Note that the supply of the inert gas may not be performed.

[0082] As the processing conditions in this step, Second raw material gas supply flow rate: 0.01 to 1 slm, preferably 0.1 to 0.5 slm Second raw material gas supply time: 1 to 100 seconds, preferably 15 to 20 seconds are exemplified. Other processing conditions can be the same as the processing conditions when the first raw material gas is supplied in step a1.

[0083] Under the above processing conditions, by supplying, for example, a chlorosilane-based gas, which will be described later, as the second source gas to the wafer 200, it becomes possible to form an Si-containing layer containing chlorine (Cl) as the third layer on the outermost surface of the wafer 200 as a base. The Si-containing layer containing Cl is formed by physical adsorption or chemical adsorption of molecules of the chlorosilane-based gas on the outermost surface of the wafer 200, physical adsorption or chemical adsorption of molecules of a substance obtained by decomposing a part of the chlorosilane-based gas, deposition of Si by thermal decomposition of the chlorosilane-based gas, and the like. The Si-containing layer containing Cl may be an adsorption layer (physical adsorption layer or chemical adsorption layer) of molecules of the chlorosilane-based gas or a substance obtained by decomposing a part of the chlorosilane-based gas, or may be a deposition layer of Si containing Cl. Note that under the above processing conditions, physical adsorption or chemical adsorption of molecules of the chlorosilane-based gas or a substance obtained by decomposing a part of the chlorosilane-based gas on the outermost surface of the wafer 200 occurs dominantly (preferably), and deposition of Si by thermal decomposition of the chlorosilane-based gas occurs slightly or hardly at all. That is, under the above processing conditions, the third layer (Si-containing layer) will predominantly contain a large amount of an adsorption layer (physical adsorption layer or chemical adsorption layer) of molecules of the chlorosilane-based gas or a substance obtained by decomposing a part of the chlorosilane-based gas, and will contain slightly or hardly any deposition layer of Si containing Cl.

[0084] After the third layer is formed, the valve 243b is closed, and the supply of the first reaction gas into the processing chamber 201 is stopped. Then, in the same processing procedure and under the same processing conditions as the purge in step a1, the gas and the like remaining in the processing chamber 201 are removed from the processing chamber 201 (purge).

[0085] As the second source gas, for example, a silane-based gas containing silicon (Si) as the main element constituting the film formed on the wafer 200 can be used. As the silane-based gas, for example, a gas containing Si and a halogen, that is, a halosilane-based gas can be used. The halogen includes chlorine (Cl), fluorine (F), bromine (Br), iodine (I), and the like. As the halosilane-based gas, for example, the above-described chlorosilane-based gas containing Si and Cl can be used.

[0086] As the second source gas, for example, tetrachlorosilane (SiCl 4 , abbreviation: STC) gas, hexachlorodisilane (Si 2 Cl 6 , abbreviation: HCDS) gas, trichlorosilane (SiHCl 3 , abbreviation: TCS) gas, dichlorosilane (SiH 2 Cl 2 , abbreviation: DCS) gas, monochlorosilane (SiH 3 Cl, abbreviation: MCS) gas and other chlorosilane-based gases can be used. Thus, as the second source gas, an inorganic gas not containing an amino group in its molecular structure can be used. As the second source gas, one or more of these can be used.

[0087] As the second source gas, in addition to chlorosilane-based gases, for example, tetrafluorosilane (SiF 4 ) gas, difluorosilane (SiH 2 F 2 ) gas and other fluorosilane-based gases, or tetrabromosilane (SiBr 4 ) gas, dibromosilane (SiH 2 Br 2 ) gas and other bromosilane-based gases, or tetraiodosilane (SiI 4 ) gas, diiodosilane (SiH 2 I 2 ) gas and other iodosilane-based gases can also be used. As the source gas, one or more of these can be used.

[0088] [Step b2] In this step, an O-containing gas and an H-containing gas are supplied as the second reaction gas to the wafer 200 in the processing chamber 201.

[0089] Specifically, open valves 243b and 243d, and flow the H-containing gas and the O-containing gas into gas supply pipes 232a and 232b, respectively. The H-containing gas and the O-containing gas flowing through gas supply pipes 232a and 232b are each adjusted in flow rate by MFCs 241a and 241b, and supplied into processing chamber 201 through nozzles 249a and 249b. The O-containing gas and the H-containing gas are mixed and react in processing chamber 201, and then are exhausted from exhaust port 231a. At this time, for wafer 200, oxidation species containing no moisture (H 2 O) containing oxygen such as atomic oxygen (O) generated by the reaction of the O-containing gas and the H-containing gas are supplied (O-containing gas and H-containing gas supply). At this time, open valves 243d and 243e, and supply an inert gas into processing chamber 201 through nozzles 249a and 249b. Note that the supply of the inert gas may not be performed.

[0090] The processing conditions in this step are as follows: Processing pressure: less than atmospheric pressure, preferably 0.1 - 20 Torr, more preferably 0.2 - 0.8 Torr O-containing gas supply flow rate: 0.1 - 10 slm, preferably 0.5 - 10 slm H-containing gas supply flow rate: 0.01 - 5 slm, preferably 0.1 - 1.5 slm Each gas supply time: 1 - 200 seconds, preferably 15 - 50 seconds Inert gas supply flow rate (per gas supply pipe): 0 - 10 slm are exemplified. Other processing conditions can be the same as the processing conditions when performing the first raw material gas supply in step a1.

[0091] By performing this step under the above-described processing conditions, at least a part of the third layer formed on the wafer 200 is oxidized (modified), and as the fourth layer, a silicon oxide layer (SiO layer) containing Si and O can be formed. When forming the fourth layer (SiO layer), impurities such as Cl contained in the third layer (Si-containing layer) constitute at least a gas-like substance containing Cl and are discharged from the processing chamber 201 during the modification reaction of the Si-containing layer by the O-containing gas and the H-containing gas. As a result, the fourth layer becomes a layer with fewer impurities such as Cl compared to the third layer formed in step b1. Further, the surface of the fourth layer is in a state terminated with OH, that is, a state in which adsorption sites are formed, as a result of the oxidation treatment with the O-containing gas and the H-containing gas.

[0092] By simultaneously and together supplying the O-containing gas and the H-containing gas into the processing chamber 201 under the above-described conditions, the O-containing gas and the H-containing gas are thermally activated (excited) non-plasma in a heated reduced-pressure atmosphere and react, whereby oxygen-containing moisture (H 2 O) non-containing oxidation species are generated. And mainly by this oxidation species, the above-described oxidation (modification) treatment is performed. According to this oxidation treatment, the oxidation power can be significantly improved compared to step a2 of supplying the O-containing gas alone. That is, by simultaneously and together adding the O-containing gas and the H-containing gas in a reduced-pressure atmosphere, a significant oxidation power improvement effect can be obtained compared to the case of supplying the O-containing gas alone.

[0093] After the fourth layer is formed, the valves 243b and 243d are closed, and the supply of the O-containing gas and the H-containing gas into the processing chamber 201 is stopped respectively. Then, the gas and the like remaining in the processing chamber 201 are removed from the processing chamber 201 (purged) by the same processing procedure and processing conditions as the purge in step a1.

[0094] As the second reaction gas, that is, the O-containing gas and the H-containing gas (O-containing gas + H-containing gas), for example, O 2 gas + hydrogen (H 2 ) gas, ozone (O 3) Gas + H 2 Gas, hydrogen peroxide (H 2 O 2 ) Gas + H 2 Gas, water vapor (H 2 O gas) + H 2 Gas, etc. can be used. In this case, as the H-containing gas, instead of H 2 gas, deuterium ( 2 H 2 ) gas can also be used. Note that in this specification, the combined description of two gases such as "O 2 gas + H 2 gas" means a mixed gas of H 2 gas and O 2 gas. When supplying the mixed gas, the two gases may be mixed (premixed) in the supply pipe and then supplied into the processing chamber 201, or the two gases may be separately supplied into the processing chamber 201 from different supply pipes and mixed (postmixed) in the processing chamber 201. As the second reaction gas, one or more of these can be used.

[0095] Also, in this step, at least one of the O-containing gas and the H-containing gas may be supplied after being plasma-excited. For example, plasma-excited O 2 gas (O 2 * ) and non-plasma-excited H 2 gas (H 2 * ) may be supplied, or non-plasma-excited O 2 gas and plasma-excited H 2 gas may be supplied, or plasma-excited O 2 gas and plasma-excited H 2 gas may be supplied.

[0096] [Performed a predetermined number of times] By performing the above steps b1 and b2 non-simultaneously, that is, without synchronization, for a predetermined number of cycles (n times, where n is an integer of 1 or more), it becomes possible to form a second SiO film as a second film with a predetermined composition and a predetermined film thickness on the wafer 200. It is preferable to repeat the above cycle a plurality of times. That is, the thickness of the fourth layer (SiO layer) formed by performing the above cycle once is made smaller than the desired film thickness, and the above cycle is preferably repeated a plurality of times until the film thickness of the second SiO film formed by laminating the fourth layer becomes the desired film thickness.

[0097] In step B, it is preferable to form the second SiO film until at least a part of the opposing second SiO films formed on the first SiO film come into contact with each other.

[0098] Also, in step B, it is preferable to form the second SiO film until the entire concave structure in the wafer 200 is filled with the first SiO film and the second SiO film.

[0099] (After purge and atmospheric pressure recovery) After the process of forming the second SiO film with the desired thickness on the wafer 200 is completed, an inert gas as a purge gas is supplied into the processing chamber 201 from each of the nozzles 249a and 249b, and exhausted from the exhaust port 231a. As a result, the inside of the processing chamber 201 is purged, and gases, reaction by-products, etc. remaining in the processing chamber 201 are removed from the processing chamber 201 (after purge). Then, the atmosphere in the processing chamber 201 is replaced with an inert gas (inert gas replacement), and the pressure in the processing chamber 201 is restored to normal pressure (atmospheric pressure recovery).

[0100] (Boat unloading and wafer discharge) After that, the seal cap 219 is lowered by the boat elevator 115, and the lower end of the manifold 209 is opened. Then, the processed wafer 200 is unloaded (boat unloading) from the lower end of the manifold 209 to the outside of the reaction tube 203 while being supported by the boat 217. After the boat unloading, the shutter 219s is moved, and the lower end opening of the manifold 209 is sealed by the shutter 219s via the O-ring 220c (shutter close). After the processed wafer 200 is unloaded to the outside of the reaction tube 203, it is taken out from the boat 217 (wafer discharge).

[0101] (3) Effects of this embodiment According to this embodiment, one or more of the following effects can be obtained.

[0102] (a) Step A of supplying a first source gas to the wafer 200 provided with a concave structure on its surface and forming a first SiO film having a predetermined adhesion force on the inner surface of the concave structure, and step B of supplying a second source gas to the wafer 200 and forming a second SiO film having an adhesion force smaller than that of the first SiO film on the first SiO film, by performing these steps, it is possible to suppress the occurrence of phenomena such as collapse and deformation of the pattern formed on the surface of the wafer 200 (hereinafter, these are collectively referred to as pattern collapse).

[0103] That is, in the above-described substrate processing step, when only the first source gas is used as the source gas and the inside of the concave structure is filled only with the first SiO film having an adhesion force greater than that of the second SiO film, when the surfaces of the first SiO films formed on the inner surface of the concave structure come into contact with each other during the progress of the formation of the first SiO film, these films tend to adhere to each other with a strong force (attract). Thus, the stress applied to the concave structure, that is, the attracting force generated between the opposing inner surfaces in the concave structure becomes large, resulting in pattern collapse (see FIG. 6).

[0104] In this aspect, not only is film formation performed using the first source gas, but film formation using the second source gas is also combined to form a second SiO film having an adhesion force smaller than that of the first SiO film on the first SiO film. As a result, compared to the case where the embedding inside the concave structure is performed only by the first SiO film, when the surfaces of the films formed on the inner surface of the concave structure come into contact with each other, the stress applied to the concave structure is reduced, and the occurrence of pattern collapse can be suppressed (see FIG. 8). According to this aspect, even when the second SiO film is formed until the entire inside of the concave structure is filled with the first SiO film and the second SiO film in step B, the occurrence of pattern collapse can be suppressed.

[0105] In this specification, "adhesion force" mainly refers to the attractive force acting between molecules on the film surface based on van der Waals forces and the like. Also, "pattern collapse" refers to a phenomenon in which adjacent patterns approach each other so as to lean against each other, and in some cases, the pattern breaks or peels off from the base.

[0106] (b) Even when an organic gas is supplied as the first source gas in step A, the occurrence of pattern collapse can be suppressed by supplying an inorganic gas as the second source gas in step B.

[0107] This is because the molecular weight of the first source gas, which is an organic gas, tends to be larger than the molecular weight of the second source gas, which is an inorganic gas. Along with this, the molecular weight on the surface of the first SiO film becomes larger than the molecular weight on the surface of the second SiO film. As the molecular weight of the molecules constituting the surface of the film increases, the adhesion force of the film tends to increase. Therefore, the adhesion force of the first SiO film becomes larger than the adhesion force of the second SiO film (see FIG. 10). In this aspect, as described above, by not only performing film formation using the first source gas but also combining film formation using the second source gas, the occurrence of pattern collapse can be suppressed.

[0108] (c) In step A, while maintaining a state where the two opposing side surfaces in the concave structure do not contact each other, the first SiO film is formed. In step B, the second SiO film is formed on the first SiO film until at least a part of the opposing second SiO films contact each other. That is, when embedding in the concave structure, the contact between the films is not caused by the first SiO film with a large adhesive force, but by the second SiO film with a small adhesive force. Thereby, compared with the case where the first SiO films having an adhesive force larger than that of the second SiO film contact each other, the stress applied to the concave structure can be reduced. Thereby, the occurrence of pattern collapse can be suppressed.

[0109] (d) Even when the concave structure provided on the surface of the wafer 200 is configured in a so-called tapered shape where the distance between the side surfaces at the lower part of the concave structure is shorter than the distance between the side surfaces at the upper part of the concave structure, the occurrence of pattern collapse can be suppressed.

[0110] This is because both the first SiO film and the second SiO film tend to have a larger adhesive force of the film as the film thickness becomes thinner (see FIG. 10). Here, when the concave structure is configured in the above-described tapered shape, near the bottom of the concave structure, the distance between the opposing side surfaces is shorter (narrower) than near the upper part of the concave structure. Therefore, during the formation of the first SiO film, the first SiO film formed on the side surface near the bottom of the concave structure is in a state where the film thickness is thinner than the first SiO film formed on the side surface near the upper part of the concave structure, that is, in a state where the adhesive force is large, and they contact each other. As a result, there is a concern that a large stress is applied to the concave structure. As a result, pattern collapse is likely to occur starting from near the bottom of the concave structure. In this aspect, in step A, while maintaining a state where the first SiO films formed on the opposing side surfaces in the concave structure do not contact each other, the first SiO film is formed, so that the occurrence of pattern collapse can be suppressed.

[0111] (e) By setting the ratio of the thickness of the first SiO film to the total thickness of the first SiO film and the second SiO film (the thickness of the stacked SiO film) to 50% or less, it is possible to avoid the surfaces of the first SiO films formed on the inner surface of the concave structure from contacting each other, thereby suppressing the occurrence of pattern collapse. When the ratio of the thickness of the first SiO film is higher than 50%, it is impossible to avoid the surfaces of the first SiO films formed on the inner surface of the concave structure from contacting each other, and there is a high possibility that pattern collapse may occur.

[0112] (f) By making the step coverage of the first SiO film formed in step A higher than the step coverage of the second SiO film formed in step B, it is possible to suppress the generation of voids and seams in the concave structure.

[0113] This is because, in the above-described substrate processing step, when only the second source gas is used as the source gas and the inside of the concave structure is filled only with the second SiO film having a step coverage lower than the step coverage of the first SiO film, the second SiO film locally grows thickly near the upper part of the concave structure, and the upper part of the concave structure is blocked before the filling of the inside of the concave structure is completed. As a result, voids and seams may occur in the concave structure (see FIG. 7).

[0114] In this aspect, not only the film formation using the second source gas is performed, but also the film formation using the first source gas is combined, and the first SiO film having a step coverage higher than the step coverage of the second SiO film is formed prior to the second SiO film, thereby suppressing the generation of voids and seams in the concave structure (see FIG. 8). According to this aspect, even when the second SiO film is formed in step B until the entire inside of the concave structure is filled with the first SiO film and the second SiO film, the generation of voids and seams in the concave structure can be suppressed.

[0115] (g) In step A, by using a gas containing an amino group in its molecular structure as the first source gas, the generation of voids and seams in the concave structure can be suppressed.

[0116] This is because when a gas containing an amino group in its molecular structure is used as the source gas, the surface reaction between the source gas molecules and the surface of the wafer 200 can be optimized compared to the case where a gas not containing an amino group in its molecular structure is used, and the step coverage of the formed film can be improved. In this embodiment, a first source gas containing an amino group in its molecular structure is supplied prior to a second source gas not containing an amino group in its molecular structure, and a first SiO film having a step coverage higher than that of the second SiO film is formed prior to the second SiO film, whereby the generation of voids, seams, etc. in the concave structure can be suppressed.

[0117] (h) By making the oxidizing power of the first reaction gas supplied in step A smaller than the oxidizing power of the second reaction gas supplied in step B, oxidation of the surface of the wafer 200 as a base can be suppressed in step A.

[0118] Also, by making the oxidizing power of the second reaction gas supplied in step B larger than the oxidizing power of the first reaction gas supplied in step A, the second SiO film formed in step B can be sufficiently oxidized in step B. Further, even if there is an insufficiently oxidized region remaining in the first SiO film formed in step A, in step B, such a region can be sufficiently oxidized by utilizing the high oxidizing power of the second reaction gas.

[0119] In this way, in this embodiment, it becomes possible to achieve both suppression of oxidation of the base and reliable oxidation of the first SiO film and the second SiO film.

[0120] In addition, in each of Steps A and B, when only the first reaction gas with low oxidizing power is used as the reaction gas, even if oxidation of the substrate can be suppressed, oxidation of the first SiO film and the second SiO film may be insufficient. Further, in each of Steps A and B, when only the second reaction gas with high oxidizing power is used as the reaction gas, even if the first SiO film and the second SiO film can be sufficiently oxidized, it may not be possible to suppress oxidation of the substrate.

[0121] (i) By setting the ratio of the thickness of the first SiO film to the total thickness of the first SiO film and the second SiO film (the thickness of the stacked SiO film) to 10% or more, oxidation of the substrate by the second reaction gas supplied in Step B can be suppressed. In addition, the step coverage of the formed stacked SiO film can be improved. If the ratio of the thickness of the first SiO film is lower than 10%, oxidation of the substrate may not be suppressed. In addition, the step coverage of the formed stacked SiO film may decrease.

[0122] (4) Modification The substrate processing sequence in this embodiment can be changed as in the following modification examples. Unless otherwise specified, the processing procedures and conditions in each step of each modification example can be the same as those in each step of the above-described substrate processing sequence.

[0123] Similar to the processing sequence in the above-described embodiment, after performing Step A, in addition to performing Step B, the order of performing each step can be changed as in the processing sequence shown in FIG. 5 and below, and Step A may be performed after performing Step B. In this modification example, in Step B, it is preferable to form the second SiO film until the second SiO films formed on the opposing side surfaces in the concave structure provided on the surface of the wafer 200 are in contact with each other (film thickness). More preferably, the second SiO film is formed until at least a part of the bottom in the concave structure is filled with the second SiO film having a smaller adhesion force than the first SiO film.

[0124] (Second source gas → second reaction gas) × n → (first source gas → first reaction gas) × m

[0125] Note that, as in the gas supply sequence shown below, it is preferable to supply (preflow) an O-containing gas and an H-containing gas as the second reaction gas to the wafer 200 before performing step B. The processing procedure in this step can be the same as the processing procedure in step b2 described above.

[0126] Second reaction gas → (second source gas → second reaction gas) × n → (first source gas → first reaction gas) × m

[0127] As the conditions in this step, Processing pressure: less than atmospheric pressure, preferably 0.1 to 20 Torr, more preferably 0.2 to 0.8 Torr O-containing gas supply flow rate: 0.1 to 10 slm, preferably 0.5 to 10 slm H-containing gas supply flow rate: 0.01 to 5 slm, preferably 0.1 to 1.5 slm Each gas supply time: 1 to 200 seconds, preferably 15 to 50 seconds Inert gas supply flow rate (per gas supply pipe): 0 to 10 slm are exemplified. Other processing conditions can be the same as the processing conditions when supplying the first source gas for OH terminal formation.

[0128] By performing this step under the above-described processing conditions, hydroxyl terminals (OH terminals) can be formed over the entire surface of the wafer 200. The OH terminals present on the surface of the wafer 200 function as adsorption sites for the source gas, that is, adsorption sites for molecules and atoms constituting the source gas, in the film formation process described later.

[0129] After the OH terminals are formed, valves 243b and 243d are closed, and the supply of the O-containing gas and the H-containing gas into the processing chamber 201 is stopped respectively. Then, in the same processing procedure and under the same processing conditions as the purge in step a1, the gas and the like remaining in the processing chamber 201 are removed from the processing chamber 201 (purge).

[0130] In step B, it is preferable that the ratio of the thickness of the second SiO film to the total thickness of the first SiO film as the first film and the second SiO film as the second film is 90% or less. By setting such a ratio, oxidation of the substrate by the second reaction gas supplied in step B can be suppressed. In addition, the step coverage of the formed laminated SiO film can be improved. If the ratio of the thickness of the second SiO film is higher than 90%, oxidation of the substrate may not be suppressed. In addition, the step coverage of the formed laminated SiO film may decrease.

[0131] In step B, it is preferable that the ratio of the thickness of the second SiO film to the total thickness of the first SiO film as the first film and the second SiO film as the second film is 50% or more. By setting such a ratio, contact between the surfaces of the first SiO films formed on the inner surface of the concave structure can be avoided, and the occurrence of pattern collapse can be suppressed. If the ratio of the thickness of the second SiO film is lower than 50%, it is impossible to avoid contact between the surfaces of the first SiO films formed on the inner surface of the concave structure, and pattern collapse may highly likely occur.

[0132] In this modified example, in step B, at least the bottom part in the concave structure is filled to some extent with the second SiO film as the second film having a smaller adhesion force than the first SiO film as the first film, and then step A is performed. Therefore, the occurrence of pattern collapse starting from the bottom can be suppressed (see FIG. 9).

[0133] <Other aspects of the present disclosure> The aspects of the present disclosure have been specifically described above. However, the present disclosure is not limited to the above-described aspects, and various modifications can be made without departing from the gist thereof.

[0134] In the above-described embodiment, an example has been described in which by performing Step A and Step B in this order, a SiO film (laminated SiO film) in which a first SiO film and a second SiO film are laminated is formed on the wafer 200. However, the present disclosure is not limited to such an embodiment. For example, Step A and Step B may be performed in this order, and after Step B, Step A may be further performed to form a SiO film in which a first SiO film, a second SiO film, and a first SiO film are laminated in this order on the wafer 200. Since the second Step A is performed in a state where the concave structure is filled to some extent with the first SiO film and the second SiO film, the occurrence of pattern collapse can be suppressed. Furthermore, since the filling of the concave structure with the first SiO film having excellent step coverage can be performed by the second Step A, the occurrence of voids and seams can be more reliably suppressed.

[0135] In the above-described embodiment, an example has been described in which each of Step A and Step B is performed in the same processing chamber 201 (in-situ). However, the present disclosure is not limited to such an embodiment. For example, Step A and Step B may be performed in other processing chambers (ex-situ). In this case, it is preferable not to expose the wafer 200 to the atmosphere between Step A and Step B. Even in these cases, effects similar to those in the above-described embodiment can be obtained.

[0136] In the above-described embodiment, an example has been described in which in Step B, the second SiO film is formed until the entire concave structure is filled. However, the present disclosure is not limited to such an embodiment. For example, in Step B, the second SiO film may be formed so as to fill at least a part of the concave structure. Even in this case, effects similar to those in the above-described embodiment can be obtained.

[0137] For example, in step A and step B, not only SiO films but also silicon-based oxide films such as silicon carbon oxide film (SiOC film), silicon carbon oxynitride film (SiOCN film), silicon oxynitride film (SiON film), silicon boron oxynitride film (SiBON film), silicon boron carbon oxynitride film (SiBOCN film), etc. may be formed. Also, in step A and step B, metal-based oxide films such as aluminum oxide film (AlO film), titanium oxide film (TiO film), hafnium oxide film (HfO film), zirconium oxide film (ZrO film), etc. may be formed respectively.

[0138] In the above aspect, an example of forming a film using a batch-type substrate processing apparatus that processes a plurality of substrates at once has been described. The present disclosure is not limited to the above aspect, and for example, it can also be suitably applied when forming a film using a single-wafer type substrate processing apparatus that processes one or several substrates at once. Also, in the above aspect, an example of forming a film using a substrate processing apparatus having a hot-wall type processing furnace has been described. The present disclosure is not limited to the above aspect, and it can also be suitably applied when forming a film using a substrate processing apparatus having a cold-wall type processing furnace.

[0139] Even when using these substrate processing apparatuses, each process can be performed with the same processing procedures and processing conditions as in the above aspect, and the same effects as in the above aspect can be obtained.

[0140] The above aspects can be used in appropriate combinations. The processing procedures and processing conditions at this time can be, for example, the same as the processing procedures and processing conditions of the above aspects.

Example

[0141] Using the above substrate processing apparatus, by performing the processing sequence of the above aspect on a wafer provided with a concave structure on its surface, a first SiO film and a second SiO film were formed so as to fill the concave structure, and sample 1 was fabricated. When fabricating sample 1, (dimethylamino)trimethoxysilane gas was used as the first raw material gas, and O was used as the first reaction gas. 2Gas, HCDS gas as the second source gas, and O as the second reaction gas 2 Gas + hydrogen (H 2 ) gas was used.

[0142] Using the above-described substrate processing apparatus, for a wafer having the same configuration as the wafer used when producing Sample 1, by performing the processing sequence of the above-described modification example, the first SiO film and the second SiO film were formed so as to fill the concave structure, and Sample 2 was produced. When producing Sample 2, the first source gas, the first reaction gas, the second source gas, and the second reaction gas were each the same gas as the gas used when producing Sample 1.

[0143] Using the above-described substrate processing apparatus, for a wafer having the same configuration as the wafer used when producing Sample 1, by performing only Step A of the processing sequence of the above-described aspect, the first SiO film was formed so as to fill the concave structure, and Sample 3 was produced. When producing Sample 3, the first source gas and the first reaction gas were each the same gas as the gas used when producing Sample 1. Other processing conditions were the same as the processing conditions in Step A of Sample 1.

[0144] Using the above-described substrate processing apparatus, for a wafer having the same configuration as the wafer used when producing Sample 1, by performing only Step B of the processing sequence of the above-described aspect, the second SiO film was formed so as to fill the concave structure, and Sample 4 was produced. When producing Sample 4, the second source gas and the second reaction gas were each the same gas as the gas used when producing Sample 1. Other processing conditions were the same as the processing conditions in Step B of Sample 1.

[0145] Then, the presence or absence of pattern collapse and the possibility of suppressing the oxidation of the substrate in Samples 1 to 4 were examined.

[0146] The presence or absence of pattern collapse was determined by observing the cross-sectional TEM image of the SiO film formed on the pattern. When observing the cross-sectional TEM image, it was confirmed that more pattern collapse occurred in Sample 3 supplied with only the first source gas (organic gas) as the source gas than in Sample 4 supplied with only the second source gas (inorganic gas) as the source gas. For each of Samples 3 and 4, a histogram was created with the distance between adjacent patterns (the distance between the side surfaces at the upper part of the concave structure formed on the surface of the wafer) on the horizontal axis and the number of occurrences of adjacent patterns at each distance on the vertical axis. It was found that the distance between adjacent patterns had more variation in Sample 3 than in Sample 4. Therefore, for each of Samples 3 and 4, the standard deviation (nm) of the distance between adjacent patterns was determined, and the result was that the standard deviation of Sample 3 was larger than the standard deviation of Sample 4. From this result, regarding the presence or absence of pattern collapse, the standard deviation of Sample 4 was used as the threshold for determination. For each of Samples 1 and 2, the standard deviation (nm) of the distance between adjacent patterns was determined, and the result was that the standard deviations of Samples 1 and 2 were smaller than the standard deviation of Sample 4. Accordingly, it was determined that pattern collapse did not occur in Samples 1 and 2.

[0147] The feasibility of suppressing the oxidation of the substrate was determined by observing the cross-sectional TEM images of the SiO films formed on the patterns of Samples 1 to 4 and measuring the thickness (nm) of the oxide film on the surface of the wafer, which is the substrate, as the amount of substrate oxidation for each. When measuring the thickness of the oxide film on the surfaces of Samples 1 to 4, the thickness of the oxide film of Sample 1 was 1.2 (nm), the thickness of the oxide film of Sample 2 was 1.4 (nm), the thickness of the oxide film of Sample 3 was 0.6 (nm), and the thickness of the oxide film of Sample 4 was 1.5 (nm). From this result, the feasibility of suppressing the oxidation of the substrate was determined with the thickness of the oxide film of Sample 4, 1.5 (nm), as the threshold. Since the thicknesses of the oxide films of Samples 1 and 2 were smaller than the thickness of the oxide film of Sample 4, it was determined that the oxidation of the substrate was suppressed in Samples 1 and 2.

Explanation of Signs

[0148] 200 wafers 201 processing chamber

Claims

1. (a) A step of supplying a first source gas and a step of supplying a first oxidizing gas to a substrate having a concave structure on its surface are performed a predetermined number of times in a cycle, thereby forming a first film, which is an oxide film having a predetermined adhesive force, on the inner surface of the concave structure; (b) A step of supplying a second source gas and a step of supplying a second oxidizing gas having a greater oxidizing power than the first oxidizing gas to the substrate are performed a predetermined number of times in a cycle, thereby forming a second film, which is an oxide film having an adhesive force smaller than that of the first film, on the first film; A substrate processing method comprising the above.

2. The inner surface of the concave structure has opposing side surfaces and a bottom surface; In (a), the first film is formed while maintaining a state in which the first films formed on the opposing side surfaces do not contact each other; In (b), the second film is formed until at least a part of the opposing second films contact each other. The substrate processing method according to Claim 1.

3. The step coverage of the first film is higher than that of the second film. The substrate processing method according to Claim 1.

4. The molecular weight of the first source gas is greater than that of the second source gas. The substrate processing method according to Claim 1.

5. The first source gas is an organic gas; The second source gas is an inorganic gas. The substrate processing method according to Claim 4.

6. In (b), the second film is formed until at least a part of the concave structure is filled with the first film and the second film. The substrate processing method according to Claim 1.

7. In (b), the second film is formed until the entire concave structure is filled with the first film and the second film. The substrate processing method according to Claim 6.

8. The inner surface of the concave structure has opposing side surfaces; The distance between the side surfaces at the lower part of the concave structure is shorter than the distance between the side surfaces at the upper part of the concave structure. The substrate processing method according to Claim 1.

9. A step of supplying a first source gas containing a predetermined element to a substrate having a concave structure on its surface, and forming a first film containing the predetermined element and having a predetermined adhesive force on the inner surface of the concave structure; A step of supplying a second source gas containing the predetermined element to the substrate, and forming a second film containing the predetermined element and having an adhesive force smaller than that of the first film on the first film; Comprising the above, A substrate processing method in which an amino group is bonded to one bond of an atom of the predetermined element contained in the first source gas, and alkoxy groups are bonded to the remaining three bonds.

10. In (a), it is a condition in which the amino group is desorbed without the alkoxy group being desorbed from the atom of the predetermined element, and the atom of the predetermined element in a state where the amino group is desorbed and the bond with the alkoxy group is maintained is adsorbed on the surface of the substrate. The substrate processing method according to claim 9, wherein the first source gas is supplied to the substrate under the condition.

11. The substrate processing method according to claim 9, wherein the first source gas is a dialkylaminotrialkoxysilane gas.

12. The substrate processing method according to any one of claims 9 to 11, wherein the second source gas has a molecular structure containing a halogen element bonded to an atom of the predetermined element.

13. After (b), (a) is further performed to form the first film on the second film. The substrate processing method according to claim 1.

14. (a) A step of supplying a first source gas and a step of supplying a first oxidation gas to a substrate provided with a concave structure on its surface are performed a predetermined number of times, and a first film which is an oxide film having a predetermined adhesion force is formed on the inner surface of the concave structure. (b) A step of supplying a second source gas and a step of supplying a second oxidation gas having a greater oxidizing power than the first oxidation gas to the substrate are performed a predetermined number of times, and a second film which is an oxide film having an adhesion force smaller than the adhesion force of the first film is formed on the first film. A method for manufacturing a semiconductor device having the above.

15. A first source gas supply system for supplying a first source gas to a substrate, A second source gas supply system for supplying a second source gas having a molecular structure different from that of the first source gas to the substrate, A first oxidation gas supply system for supplying a first oxidation gas to the substrate, A second oxidation gas supply system for supplying a second oxidation gas having a greater oxidizing power than the first oxidation gas to the substrate, Performing a cycle including a process of supplying the first source gas and a process of supplying the first oxidation gas to the substrate provided with a concave structure on its surface a predetermined number of times to form a first film which is an oxide film having a predetermined adhesion force on the inner surface of the concave structure; and (b) performing a cycle including a process of supplying the second source gas and a process of supplying the second oxidation gas to the substrate a predetermined number of times to form a second film which is an oxide film having an adhesion force smaller than that of the first film on the first film. A control unit configured to be able to control the first source gas supply system, the second source gas supply system, the first oxidation gas supply system, and the second oxidation gas supply system so as to perform the above processes. A substrate processing apparatus having the above.

16. (a) A procedure of forming a first film which is an oxide film having a predetermined adhesion force on the inner surface of the concave structure by performing a cycle including a procedure of supplying a first source gas and a procedure of supplying a first oxidation gas to a substrate provided with a concave structure on its surface a predetermined number of times; (b) A procedure of forming a second film which is an oxide film having an adhesion force smaller than that of the first film on the first film by performing a cycle including a procedure of supplying a second source gas and a procedure of supplying a second oxidation gas having a greater oxidizing power than the first oxidation gas to the substrate a predetermined number of times. A program for causing a computer to execute the above on a substrate processing apparatus.

17. (a) A step of supplying a first source gas containing a predetermined element to a substrate provided with a concave structure on its surface and forming a first film containing the predetermined element and having a predetermined adhesion force on the inner surface of the concave structure; (b) A step of supplying a second source gas containing the predetermined element to the substrate and forming a second film containing the predetermined element and having an adhesion force smaller than that of the first film on the first film. Having the above, A method for manufacturing a semiconductor device in which an amino group is bonded to one bond of an atom of the predetermined element contained in the first source gas and alkoxy groups are bonded to the remaining three bonds.

18. A first source gas supply system for supplying a first source gas containing a predetermined element to a substrate; A second source gas supply system for supplying a second source gas containing the predetermined element and having a molecular structure different from that of the first source gas to the substrate; A reaction gas supply system for supplying a reaction gas to the substrate; a process of supplying the first source gas to the substrate having a concave structure on its surface and forming a first film containing the predetermined element and having a predetermined adhesion force on the inner surface of the concave structure; and (b) a process of supplying the second source gas to the substrate and forming a second film containing the predetermined element and having an adhesion force smaller than that of the first film on the first film, and a control unit configured to be able to control the first source gas supply system, the second source gas supply system, and the reaction gas supply system so as to perform the processes. having a substrate processing apparatus in which an amino group is bonded to one bond of an atom of the predetermined element contained in the first source gas, and alkoxy groups are bonded to the remaining three bonds. According to claim 19, (a) a procedure of supplying a first source gas containing a predetermined element, wherein an amino group is bonded to one bond of an atom of the predetermined element, and alkoxy groups are bonded to the remaining three bonds, to a substrate having a concave structure on its surface and forming a first film containing the predetermined element and having a predetermined adhesion force on the inner surface of the concave structure; and (b) a procedure of supplying a second source gas containing the predetermined element to the substrate and forming a second film containing the predetermined element and having an adhesion force smaller than that of the first film on the first film. A program that causes a computer to execute the procedure on a substrate processing apparatus.

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