Method of processing substrate, method of manufacturing semiconductor device, substrate processing device, and program

Abstract

To provide a technique capable of forming a film in a concave portion provided on a surface of a substrate with high accuracy.SOLUTION: The invention provides a technique of performing the steps of: (a) forming a first film in a concave portion by supplying a first film-forming agent to a substrate on a surface of which the concave portion is provided; (b) forming a second film on the first film formed in the concave portion, the second film having a chemical composition different than the first film, by supplying a second film-forming agent to the substrate; (c) modifying a part of the second film by supplying a modifying agent containing fluorine and oxygen to the substrate; and (d) removing the modified part of the second film by supplying an etching agent containing halogen to the substrate.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] BACKGROUND ART One process for manufacturing a semiconductor device involves supplying a raw material to a substrate having recesses such as trenches and holes formed on its surface, and forming a film in the recesses (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 003662 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a technique that enables a film to be formed with high precision in a recess provided on the surface of a substrate. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, (a) supplying a first film-forming agent to a substrate having a recess formed on its surface to form a first film in the recess; (b) supplying a second film-forming agent to the substrate to form a second film on the first film formed in the recess, the second film having a chemical composition different from that of the first film; (c) modifying a portion of the second film by supplying a fluorine-containing modifying agent to the substrate; (d) removing the modified portion of the second film by supplying an etching agent containing a halogen to the substrate; Techniques for doing this are provided. [Effects of the Invention]

[0006] According to the present disclosure, it is possible to form a film with high precision in a recess provided on the surface of a substrate. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic configuration diagram of a vertical processing furnace of a substrate processing apparatus suitably used in one embodiment of the present disclosure, showing a processing furnace 202 portion in vertical cross section. [Figure 2] FIG. 2 is a schematic configuration diagram of a vertical processing furnace of a substrate processing apparatus suitably used in one embodiment of the present disclosure, and is a cross-sectional view of the processing furnace 202 taken along line AA in FIG. [Figure 3] FIG. 3 is a schematic configuration diagram of a controller 121 of a substrate processing apparatus suitably used in one embodiment of the present disclosure, and is a block diagram showing a control system of the controller 121. [Figure 4] FIG. 4 is a flow diagram showing a processing sequence according to one embodiment of the present disclosure. [Figure 5] FIG. 5(a) is a cross-sectional view showing a wafer surface portion after a first film-forming agent is applied to a wafer having recesses on its surface to form a silicon oxide film (SiO film) as a first film in the recesses. FIG. 5(b) is a cross-sectional view showing a wafer surface portion after a second film-forming agent is applied to the wafer in the state of FIG. 5(a) to form a silicon nitride film (SiN film) as a second film having voids on the SiO film formed in the recesses. FIG. 5(c) is a cross-sectional view showing a wafer surface portion after a fluorine (F)-containing modifier is applied to the wafer in the state of FIG. 5(b) to modify a portion of the SiN film having voids. FIG. 5(d) is a cross-sectional view showing a wafer surface portion after a halogen-containing etchant is applied to the wafer in the state of FIG. 5(c) to remove the modified portion (modified layer) of the SiN film. Figure 5(e) is a schematic cross-sectional view showing the wafer surface portion after a third film-forming agent is supplied to the wafer in the state shown in Figure 5(d) to form a SiN film as a third film on the SiN film after removing the modified layer. DETAILED DESCRIPTION OF THE INVENTION

[0008] <One aspect of the present disclosure> Hereinafter, one embodiment of the present disclosure will be described mainly with reference to Figures 1 to 3, 4, and 5(a) to 5(e). Note that the drawings used in the following description are all schematic, and the dimensional relationships between elements, the ratios of elements, etc. shown in the drawings do not necessarily match those in reality. Furthermore, the dimensional relationships between elements, the ratios of elements, etc. do not necessarily match between multiple drawings.

[0009] (1) Configuration of the substrate processing equipment 1, the processing furnace 202 has a heater 207 as a temperature regulator (heating unit). The heater 207 is cylindrical and is installed vertically by being supported by a holding plate. The heater 207 also functions as an activation mechanism (excitation unit) that activates (excites) gases with heat.

[0010] A reaction tube 203 is disposed concentrically with the heater 207 inside the heater 207. The reaction tube 203 is made of a heat-resistant material such as quartz (SiO2) or silicon carbide (SiC) and has a cylindrical shape with a closed upper end and an open lower end. A manifold 209 is disposed concentrically with the reaction tube 203 below the reaction tube 203. The manifold 209 is made of a metal material such as stainless steel (SUS) and has a cylindrical shape with open upper and lower ends. The upper end of the manifold 209 engages with the lower end of the reaction tube 203 and is configured 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, similar to the heater 207. The reaction tube 203 and the manifold 209 mainly constitute a processing vessel (reaction vessel). A processing chamber 201 is formed in the cylindrical hollow portion of the processing vessel. The processing chamber 201 is configured to be able to accommodate wafers 200 as substrates. In the processing chamber 201, processing of the wafers 200 is performed.

[0011] Nozzles 249a to 249c serving as first to third supply units are respectively provided in the processing chamber 201 so as to penetrate the sidewall of the manifold 209. The nozzles 249a to 249c are also referred to as first to third nozzles, respectively. The nozzles 249a to 249c are made of a heat-resistant material such as quartz or SiC. Gas supply pipes 232a to 232c are connected to the nozzles 249a to 249c, respectively. The nozzles 249a to 249c are different nozzles, and each of the nozzles 249a and 249c is provided adjacent to the nozzle 249b.

[0012] Gas supply pipes 232a-232c are provided with mass flow controllers (MFCs) 241a-241c, which are flow rate control devices (flow rate control parts), and valves 243a-243c, which are on-off valves, in order from the upstream side of the gas flow. Gas supply pipes 232d and 232f are connected to gas supply pipe 232a downstream of valve 243a. Gas supply pipes 232e and 232g are connected to gas supply pipe 232b downstream of valve 243b. Gas supply pipe 232h is connected to gas supply pipe 232c downstream of valve 243c. Gas supply pipes 232d-232h are provided with MFCs 241d-241h and valves 243d-243h, in order from the upstream side of the gas flow. Gas supply pipes 232a-232h are made of a metal material, such as SUS.

[0013] As shown in FIG. 2, the nozzles 249a to 249c are respectively provided in an annular space between the inner wall of the reaction tube 203 and the wafers 200 in a plan view, extending from the lower part to the upper part of the inner wall of the reaction tube 203 and rising upward in the arrangement direction of the wafers 200. That is, the nozzles 249a to 249c are respectively provided in regions horizontally surrounding the wafer arrangement region on the sides of the wafer arrangement region where the wafers 200 are arranged, and extending along the wafer arrangement region. In a plan view, the nozzle 249b is disposed so as to face an exhaust port 231a (described later) on a straight line across the center of the wafer 200 loaded into the processing chamber 201. The nozzles 249a and 249c are disposed so as to sandwich a line L passing through the nozzle 249b and the center of the exhaust port 231a along the inner wall of the reaction tube 203 (the outer periphery of the wafers 200) from both sides. The line L also passes through the nozzle 249b and the center of the wafer 200. In other words, the nozzle 249c can be said to be provided on the opposite side of the nozzle 249a across the line L. The nozzles 249a and 249c are arranged symmetrically with respect to the line L as the axis of symmetry. Gas supply holes 250a to 250c for supplying gas are provided on the side surfaces of the nozzles 249a to 249c, respectively. Each of the gas supply holes 250a to 250c opens to face (face) the exhaust port 231a in a plan view, and is able to supply gas toward the wafers 200. A plurality of the gas supply holes 250a to 250c are provided from the bottom to the top of the reaction tube 203.

[0014] A raw material (raw material gas) is supplied from the gas supply pipe 232a into the processing chamber 201 via the MFC 241a, the valve 243a, and the nozzle 249a. The raw material is used as one of the first film forming agents, one of the second film forming agents, and one of the third film forming agents. When the raw material is used as the first film forming agent, the second film forming agent, or the third film forming agent, it can also be referred to as the first raw material (first raw material gas), the second raw material (second raw material gas), or the third raw material (third raw material gas), respectively.

[0015] A first reactant (first reactant gas) is supplied from gas supply pipe 232b through MFC 241b, valve 243b, and nozzle 249b into processing chamber 201. The first reactant is used as one of the first film forming agents.

[0016] A second reactant (second reactant gas) is supplied from gas supply pipe 232c into processing chamber 201 via MFC 241c, valve 243c, and nozzle 249c. The second reactant is used as one of the second film forming agents and also as one of the third film forming agents. When the second reactant is used as the second film forming agent or the third film forming agent, they can also be referred to as the second reactant (second reactant gas) and the third reactant (third reactant gas), respectively.

[0017] A modifying agent (modifying gas) is supplied from the gas supply pipe 232d into the processing chamber 201 via the MFC 241d, the valve 243d, the gas supply pipe 232a, and the nozzle 249a.

[0018] An etching agent (etching gas) is supplied from the gas supply pipe 232e into the processing chamber 201 via the MFC 241e, the valve 243e, and the nozzle 249b.

[0019] Inert gas is supplied from the gas supply pipes 232f to 232h through the MFCs 241f to 241h, the valves 243f to 243h, the gas supply pipes 232a to 232c, and the nozzles 249a to 249c into the processing chamber 201. The inert gas acts as a purge gas, a carrier gas, a dilution gas, etc.

[0020] A raw material supply system (raw material gas supply system) is mainly constituted by the gas supply pipe 232a, MFC 241a, and valve 243a. A first reactant supply system (first reactant gas supply system) is mainly constituted by the gas supply pipe 232b, MFC 241b, and valve 243b. A second reactant supply system (second reactant gas supply system) is mainly constituted by the gas supply pipe 232c, MFC 241c, and valve 243c. A modifying agent supply system (modifying gas supply system) is mainly constituted by the gas supply pipe 232d, MFC 241d, and valve 243d. An etching agent supply system (etching gas supply system) is mainly constituted by the gas supply pipe 232e, MFC 241e, and valve 243e. An inert gas supply system is mainly composed of the gas supply pipes 232f to 232h, the MFCs 241f to 241h, and the valves 243f to 243h.

[0021] Either or both of the raw material supply system and the first reactant supply system are also referred to as a first film-forming agent supply system. Either or both of the raw material supply system and the second reactant supply system are also referred to as a second film-forming agent supply system and a third film-forming agent supply system.

[0022] Any or all of the various supply systems described above may be configured as an integrated supply system 248 in which the valves 243a-243h, MFCs 241a-241h, etc. are integrated. The integrated supply system 248 is connected to each of the gas supply pipes 232a-232h, and is configured so that the supply operation of various substances (various gases) into the gas supply pipes 232a-232h, i.e., the opening and closing operation of the valves 243a-243h and the flow rate adjustment operation by the MFCs 241a-241h, etc., are controlled by a controller 121, which will be described later. The integrated supply system 248 is configured as an integrated or separate integrated unit, and can be attached and detached to and from the gas supply pipes 232a-232h, etc., so that maintenance, replacement, expansion, etc. of the integrated supply system 248 can be performed on an integrated unit basis.

[0023] An exhaust port 231a for exhausting the atmosphere inside the processing chamber 201 is provided at the bottom of the sidewall of the reaction tube 203. As shown in FIG. 2, the exhaust port 231a is provided at a position facing (opposite) the nozzles 249a-249c (gas supply holes 250a-250c) across the wafer 200 in a plan view. The exhaust port 231a may be provided along the sidewall of the reaction tube 203 from the bottom to the top, i.e., along the wafer arrangement area. An exhaust pipe 231 is connected to the exhaust port 231a. A vacuum pump 246 serving as a vacuum exhaust device is connected to the exhaust pipe 231 via a pressure sensor 245 serving as a pressure detector (pressure detection unit) for detecting the pressure inside the processing chamber 201 and an APC (Auto Pressure Controller) valve 244 serving as a pressure regulator (pressure adjustment unit). The APC valve 244 is configured to be able to evacuate and stop the evacuation of the processing chamber 201 by opening and closing the valve while the vacuum pump 246 is operating, and further, to be able to adjust the pressure inside the processing chamber 201 by adjusting the valve opening based on pressure information detected by the pressure sensor 245 while the vacuum pump 246 is operating. An exhaust system is mainly configured 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.

[0024] Below the manifold 209, a seal cap 219 is provided as a furnace port cover capable of airtightly closing the lower end opening of the manifold 209. The seal cap 219 is made of a metal material such as SUS and is formed in a disk shape. An O-ring 220b is provided on the upper surface of the seal cap 219 as a sealing member that abuts against the lower end of the manifold 209. Below the seal cap 219, a rotation mechanism 267 is provided to rotate the boat 217 (described later). A 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 boat 217, thereby rotating the wafers 200. The seal cap 219 is configured to be vertically raised and lowered by a boat elevator 115 as a lifting mechanism installed outside the reaction tube 203. The boat elevator 115 is configured as a transfer device (transfer mechanism) that transfers the wafers 200 into and out of the processing chamber 201 by raising and lowering the seal cap 219.

[0025] A shutter 219s is provided below the manifold 209 as a furnace port cover that can airtightly close the lower end opening of the manifold 209 when the seal cap 219 is lowered and the boat 217 is removed from the processing chamber 201. The shutter 219s is made of a metal material such as SUS and has a disk shape. An O-ring 220c is provided on the upper surface of the shutter 219s as a sealing member that abuts against the lower end of the manifold 209. The opening and closing operation (lifting and lowering operation, rotating operation, etc.) of the shutter 219s is controlled by a shutter opening and closing mechanism 115s.

[0026] The boat 217 as a substrate support is configured to support a plurality of wafers 200, for example, 25 to 200 wafers 200, in a horizontal position and aligned vertically with their centers aligned, i.e., arranged at intervals, in multiple stages. The boat 217 is made of a heat-resistant material such as quartz or SiC. At the bottom of the boat 217, heat insulating plates 218, also made of a heat-resistant material such as quartz or SiC, are supported in multiple stages.

[0027] A temperature sensor 263 serving as a temperature detector is installed inside the reaction tube 203. By adjusting the power supply to the heater 207 based on the temperature information detected by the temperature sensor 263, the temperature inside the processing chamber 201 can be adjusted to a desired temperature distribution. The temperature sensor 263 is installed along the inner wall of the reaction tube 203.

[0028] 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 is connected to the controller 121. An external storage device 123 can also be connected to the controller 121.

[0029] The storage device 121c is configured with, for example, a flash memory, an HDD (Hard Disk Drive), an SSD (Solid State Drive), etc. Control programs for controlling the operation of the substrate processing apparatus, process recipes describing procedures and conditions for substrate processing (described later), etc., are readably stored in the storage device 121c. The process recipe is a combination of procedures for substrate processing (described later) that are executed by the controller 121 in the substrate processing apparatus to obtain a predetermined result, and functions as a program. Hereinafter, the process recipes, control programs, etc. are collectively referred to simply as programs. The process recipes are also simply referred to as recipes. In this specification, the term "program" may refer to a recipe alone, a control program alone, or both. The RAM 121b is configured as a memory area (work area) for temporarily storing programs, data, etc. read by the CPU 121a.

[0030] The I / O port 121d is connected to the above-mentioned MFCs 241a to 241h, valves 243a to 243h, 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.

[0031] The CPU 121a is configured to read and execute a control program from the storage device 121c, and to read a recipe from the storage device 121c in response to input of an operation command from the input / output device 122. The CPU 121a is configured to control, in accordance with the contents of the read recipe, the flow rate adjustment operation of various substances (various gases) by the MFCs 241a to 241h, the opening and closing operation of the valves 243a to 243h, the opening and closing operation of the APC valve 244 and 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 operation of the boat 217 by the rotation mechanism 267, the lifting and lowering operation of the boat 217 by the boat elevator 115, the opening and closing operation of the shutter 219s by the shutter opening and closing mechanism 115s, and the like.

[0032] The controller 121 can be configured by installing the above-mentioned program stored in the external storage device 123 into a computer. The external storage device 123 includes, for example, a magnetic disk such as an HDD, an optical disk such as a CD, a magneto-optical disk such as an MO, and a semiconductor memory such as a USB memory or an SSD. The storage device 121c and the external storage device 123 are configured as computer-readable recording media. Hereinafter, these will be collectively referred to simply as recording media. When the term recording media is used in this specification, it may include only the storage device 121c alone, only the external storage device 123 alone, or both. Note that the program may be provided to the computer using a communication means such as the Internet or a dedicated line, without using the external storage device 123.

[0033] (2) Substrate processing process An example of a processing sequence for forming a film in recesses such as trenches and holes provided in the surface of a wafer 200 serving as a substrate using the above-described substrate processing apparatus as one step in the manufacturing process of a semiconductor device will be described mainly with reference to Figures 4 and 5(a) to 5(e). In the following description, a case will be described in which an SiO film, which is an oxide film, is formed as the first film, and SiN films, which are films other than SiO films, are formed as the second and third films. In the following description, the operation of each part constituting the substrate processing apparatus is controlled by a controller 121.

[0034] As shown in FIG. 4 and FIG. 5(a) to FIG. 5(e), the processing sequence in this embodiment is as follows: (a) Step A of supplying a first film-forming agent to a wafer 200 having a recess formed on its surface to form a first film (SiO film) in the recess; (b) Step B of supplying a second film-forming agent to the wafer 200 to form a second film (SiN film) having a chemical composition different from that of the first film (SiO film) on the first film (SiO film) formed in the recess; (c) Step C of supplying a fluorine-containing modifying agent to the wafer 200 to modify a part of the second film (SiN film); (d) Step D of removing the modified portion of the second film (SiN film) by supplying an etching agent containing halogen to the wafer 200; (e) Step E of supplying a third film-forming agent to the wafer 200 to form a third film (SiN film) on the second film (SiN film) after removing the modified portion; It has.

[0035] In this specification, the above-described processing sequence may be expressed as follows for convenience: Similar notations will be used in the following explanations of modified examples and other aspects.

[0036] Step A → Step B → Step C → Step D → Step E

[0037] The expression "different chemical composition" used in this specification means that at least some of the elements constituting a film, layer, or portion (e.g., a recess provided on the surface of a wafer) are different. For example, when describing a second film having a different chemical composition from a first film, it means that at least some of the elements constituting each film are different, such as an SiO film as the first film and an SiN film as the second film.

[0038] The term "wafer" used in this specification may refer to the wafer itself or to a laminate of the wafer and a predetermined layer or film formed on its surface. The term "surface of a wafer" used in this specification may refer to the surface of the wafer itself or to the surface of a predetermined layer or the like formed on the wafer. When described in this specification, "forming a predetermined layer on a wafer" may mean forming a predetermined layer directly on the surface of the wafer itself or forming a predetermined layer on a layer or the like formed on the wafer. When used in this specification, the term "substrate" is synonymous with the term "wafer".

[0039] The term "agent" used in this specification includes at least one of a gaseous substance and a liquid substance. A liquid substance includes a mist substance. That is, the first film-forming agent (raw material, first reactant), the second film-forming agent (raw material, second reactant), the third film-forming agent (raw material, second reactant), the modifier, and the etching agent may include a gaseous substance, a liquid substance such as a mist substance, or both.

[0040] The term "layer" as used herein includes at least one of a continuous layer and a discontinuous layer. For example, the Si-containing layer and the modified layer described below may include a continuous layer, a discontinuous layer, or both.

[0041] (Wafer charge and boat load) When a plurality of wafers 200 are loaded into the boat 217 (wafer charge), 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). Thereafter, 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. In this manner, the wafers 200 are prepared in the processing chamber 201.

[0042] 5(a), trench-shaped or hole-shaped recesses are provided on the surfaces of the wafers 200 loaded into the boat 217. The surfaces of the recesses provided on the wafers 200 are made of a material having a different chemical composition from the SiO film serving as the first film, that is, a material other than the SiO film, for example, silicon (Si).

[0043] (pressure and temperature regulation) After the boat loading is completed, the processing chamber 201, i.e., the space in which the wafers 200 are present, is evacuated (reduced pressure exhausted) by the vacuum pump 246 so that the interior of the processing chamber 201 is at a desired pressure (vacuum level). 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. Furthermore, the wafers 200 inside the processing chamber 201 are heated by the heater 207 so that the processing temperature is at a desired processing temperature. At this time, the power supply to the heater 207 is feedback-controlled based on temperature information detected by the temperature sensor 263 so that the processing chamber 201 has a desired temperature distribution. Furthermore, the rotation mechanism 267 starts to rotate the wafers 200. The evacuation inside the processing chamber 201 and the heating and rotation of the wafers 200 are all continued at least until the processing of the wafers 200 is completed.

[0044] (Step A) Thereafter, step A is performed. In step A, a first film-forming agent is supplied to the wafer 200 in the processing chamber 201, i.e., the wafer 200 having a recess formed on its surface, to form an SiO film as a first film in the recess. In this step, as shown in FIG. 5(a), an SiO film is formed in the recess with a thickness that leaves the opening of the recess so that an SiN film can be formed in the recess in step B, which will be performed later. Note that in this step, an SiO film is also formed on the surface (upper surface) of the wafer 200 other than the recess, as shown in FIG. 5(a).

[0045] In this step, for example, a SiO film is formed by alternately repeating a cycle of step A1 of supplying a raw material to the wafer 200 and step A2 of supplying a first reactant to the wafer 200 a predetermined number of times (m times, where m is an integer of 1 or more). The method for forming a SiO film including steps A1 and A2 will be specifically described below. In the following example, the first film-forming agent includes the raw material and the first reactant.

[0046] [Step A1] In step A1, a raw material (raw material gas) is supplied to the wafer 200 in the processing chamber 201 as a first film forming agent.

[0047] Specifically, the valve 243a is opened to allow the raw material to flow into the gas supply pipe 232a. The raw material flowing through the gas supply pipe 232a has its flow rate adjusted by the MFC 241a, is supplied into the processing chamber 201 via the nozzle 249a, and is exhausted from the exhaust port 231a. At this time, the raw material is supplied onto the wafer 200 from the side of the wafer 200. At this time, the valves 243f to 243h may be opened to supply an inert gas into the processing chamber 201 via the nozzles 249a to 249c, respectively.

[0048] The processing conditions for supplying the raw material in step A1 are as follows: Treatment temperature: 400 to 700°C, preferably 500 to 650°C Treatment pressure: 1 to 2666 Pa, preferably 67 to 1333 Pa Raw material supply flow rate: 0.01 to 2 slm, preferably 0.1 to 1 slm Raw material supply time: 1 to 120 seconds, preferably 1 to 60 seconds Inert gas supply flow rate (per gas supply pipe): 0 to 10 slm is exemplified.

[0049] In this specification, when a numerical range such as "400 to 700°C" is expressed, both the lower limit and the upper limit are included in the range. For example, "400 to 700°C" means "400°C or higher and 700°C or lower." The same applies to other numerical ranges. In this specification, the processing temperature refers to the temperature of the wafer 200 or the temperature inside the processing chamber 201, and the processing pressure refers to the pressure inside the processing chamber 201. The processing time refers to the time the processing continues. In addition, when the supply flow rate includes 0 slm, 0 slm means that the substance (gas) is not supplied. These also apply to the following explanations.

[0050] By supplying a chlorosilane-based gas containing, for example, Si and chlorine (Cl) as raw materials to the wafer 200 under the above-described processing conditions, a Si-containing layer containing Cl is formed on the inner surface of the recess of the wafer 200. The Si-containing layer containing Cl is formed on the inner surface of the recess of the wafer 200 by physical adsorption or chemical adsorption of the raw material, chemical adsorption of a substance formed by decomposition of a part of the raw material, deposition of Si due to thermal decomposition of the raw material, or the like. The Si-containing layer containing Cl may be an adsorption layer (physical adsorption layer or chemical adsorption layer) of the raw material or a substance formed by decomposition of a part of the raw material, or may be a deposition layer of Si containing Cl. In this specification, the Si-containing layer containing Cl is also simply referred to as a Si-containing layer.

[0051] After the Si-containing layer is formed, the valve 243a is closed to stop the supply of raw materials into the processing chamber 201. Then, the processing chamber 201 is evacuated to remove gases remaining in the processing chamber 201. At this time, the valves 243f to 243h are opened to supply an inert gas into the processing chamber 201 through the nozzles 249a to 249c. The inert gas supplied into the processing chamber 201 acts as a purge gas, thereby purging the processing chamber 201.

[0052] As a raw material (raw material gas) of the first film-forming agent, for example, a silane-based gas containing Si, which is the main element constituting the SiO film formed on the inner surface of the recess, can be used. As the silane-based gas, for example, a gas containing Si and a halogen element, i.e., a halosilane-based gas, can be used. Halogen includes chlorine (Cl), fluorine (F), bromine (Br), iodine (I), etc.

[0053] Examples of halosilane-based gases that can be used include chlorosilane-based gases such as monochlorosilane (SiH3Cl, abbreviated as MCS) gas, dichlorosilane (SiH2Cl2, abbreviated as DCS) gas, trichlorosilane (SiHCl3, abbreviated as TCS) gas, tetrachlorosilane (SiCl4, abbreviated as 4CS) gas, hexachlorodisilane gas (Si2Cl6, abbreviated as HCDS) gas, and octachlorotrisilane (Si3Cl8, abbreviated as OCTS) gas; fluorosilane-based gases such as tetrafluorosilane (SiF4) gas and difluorosilane (SiH2F2) gas; bromosilane-based gases such as tetrabromosilane (SiBr4) gas and dibromosilane (SiH2Br2) gas; and iodosilane-based gases such as tetraiodosilane (SiI4) gas and diiodosilane (SiH2I2) gas. Furthermore, examples of halosilane gases that can be used include alkylenechlorosilane gases such as bis(trichlorosilyl)methane ((SiCl)CH, abbreviated as BTCSM) gas and 1,2-bis(trichlorosilyl)ethane ((SiCl)CH, abbreviated as BTCSE), alkylchlorosilane gases such as 1,1,2,2-tetrachloro-1,2-dimethyldisilane ((CH)SiCl, abbreviated as TCDMDS) gas and 1,2-dichloro-1,1,2,2-tetramethyldisilane ((CH)SiCl, abbreviated as DCTMDS), and gases containing a cyclic structure composed of Si and C and a halogen, such as 1,1,3,3-tetrachloro-1,3-disilacyclobutane (CHClSi, abbreviated as TCDSCB). One or more of these can be used as the raw material.

[0054] Alternatively, a gas containing Si and hydrogen (H), i.e., silicon hydride gas, can be used as the raw material. Examples of silicon hydride gas include monosilane (SiH4) gas, disilane (Si2H6) gas, trisilane (Si3H8) gas, and tetrasilane (Si4H 10 ) gas, etc. One or more of these can be used as the raw material.

[0055] Alternatively, a gas containing Si and an amino group, i.e., an aminosilane-based gas, can be used as the raw material. The amino group can be expressed as -NH2, -NHR, or -NR2. Here, R represents an alkyl group, and the two Rs in -NR2 may be the same or different.

[0056] Examples of aminosilane gases that can be used include tetrakis(dimethylamino)silane (Si[N(CH3)2]4, abbreviated as 4DMAS) gas, tris(dimethylamino)silane (Si[N(CH3)2]3H, abbreviated as 3DMAS) gas, bis(diethylamino)silane (Si[N(C2H5)2]2H2, abbreviated as BDEAS) gas, bis(tertiarybutylamino)silane (SiH2[NH(C4H9)]2, abbreviated as BTBAS) gas, and (diisopropylamino)silane (SiH3[N(C3H7)2], abbreviated as DIPAS) gas. One or more of these can be used as the raw material.

[0057] The inert gas may be, for example, nitrogen (N2) gas or a rare gas such as argon (Ar) gas, helium (He) gas, neon (Ne) gas, or xenon (Xe) gas. One or more of these may be used as the inert gas. This also applies to each step described below.

[0058] [Step A2] After step A1 is completed, a first reactant (first reactant gas) is supplied as a first film forming agent to the wafer 200 in the processing chamber 201, that is, the wafer 200 having the Si-containing layer formed on the inner surface of the recess.

[0059] Specifically, valve 243b is opened to allow the first reactant to flow into gas supply pipe 232b. The flow rate of the first reactant flowing through gas supply pipe 232b is adjusted by MFC 241b, and the first reactant is supplied into processing chamber 201 via nozzle 249b and exhausted from exhaust port 231a. At this time, the first reactant is supplied onto wafer 200 from the side of wafer 200. At this time, an inert gas may be supplied into processing chamber 201 via each of nozzles 249a to 249c.

[0060] The processing conditions for supplying the first reactant in step A2 are: Treatment temperature: 400 to 700°C, preferably 500 to 650°C Treatment pressure: 1 to 2000 Pa, preferably 1 to 1000 Pa First reactant (oxidant, O-containing gas) supply flow rate: 0.1 to 10 slm First reactant (reducing gas (H-containing gas)) supply flow rate: 0 to 10 slm Inert gas supply flow rate (per gas supply pipe): 0 to 10 slm Each gas supply time: 1 to 120 seconds, preferably 1 to 60 seconds is exemplified.

[0061] By supplying, for example, an oxidizing agent as a first reactant to the wafer 200 under the above-described processing conditions, at least a portion of the Si-containing layer formed on the inner surface of the recess of the wafer 200 is oxidized (modified). As a result, a SiO layer is formed on the inner surface of the recess of the wafer 200 as a layer containing Si and O. When the SiO layer is formed, impurities such as Cl contained in the Si-containing layer form a gaseous substance containing at least Cl during the modification reaction (oxidation reaction) of the Si-containing layer by the first reactant, and are exhausted from the processing chamber 201. As a result, the SiO layer contains fewer impurities such as Cl than the Si-containing layer formed in step A1.

[0062] After the SiO layer is formed, the valve 243b is closed to stop the supply of the first reactant into the processing chamber 201. Then, gases remaining in the processing chamber 201 are removed (purged) from the processing chamber 201 by a processing procedure similar to the purging in step A1.

[0063] The first reactant (first reactant gas), which is one of the first film-forming agents, can be, for example, an oxidizing agent (oxidizing gas). The oxidizing agent can be used not only by being thermally excited in a non-plasma atmosphere, but also by being plasma-excited. That is, the oxidizing agent can be used by being excited into a plasma state.

[0064] Examples of oxidizing agents that can be used include oxygen (O)-containing gases such as oxygen (O) gas and ozone (O) gas; O- and H-containing gases such as water vapor (HO gas) and hydrogen peroxide (HO) gas; O- and N-containing gases such as nitrous oxide (NO) gas, nitric oxide (NO) gas, and nitrogen dioxide (NO) gas; and O- and C-containing gases such as carbon monoxide (CO) gas and carbon dioxide (CO) gas. Also, a mixed gas of the above-mentioned O-containing gas and a reducing gas can be used as the oxidizing agent. Here, a reducing gas is a substance that does not exhibit oxidizing properties by itself, but reacts with an O-containing gas under specific conditions, such as the above-mentioned processing conditions, to generate oxidizing species such as atomic oxygen, thereby improving the efficiency of the oxidation process. Examples of reducing gases include hydrogen (H) gas, deuterium ( 2 An H-containing gas such as O2 gas or H2 gas can be used. That is, the oxidizing agent can be, for example, O2 gas + H2 gas, O3 gas + H2 gas, etc. One or more of these can be used as the first reactant.

[0065] In this specification, the description of two gases together, such as "H gas + O gas," means a mixed gas of H gas and O gas. When a mixed gas is supplied, the two gases may be mixed (premixed) in a supply pipe and then supplied into the processing chamber 201, or the two gases may be supplied separately from different supply pipes into the processing chamber 201 and mixed (postmixed) in the processing chamber 201.

[0066] [Perform the specified number of times] By alternately performing the above-described steps A1 and A2, i.e., by performing the cycle of non-simultaneous processing a predetermined number of times (m times, where m is an integer equal to or greater than 1), an SiO film can be formed as a first film on the inner surface of the recess of the wafer 200, as shown in FIG. 5(a). The above-described cycle is preferably repeated multiple times. That is, it is preferable to set the thickness of the SiO layer formed per cycle to be thinner than the desired film thickness, and to repeat the above-described cycle multiple times until the thickness of the SiO film formed by stacking the SiO layers reaches the desired thickness.

[0067] In this step, the SiO film may be formed by chemical vapor deposition (CVD) in which the source material and the first reactant are simultaneously supplied. For example, in this step, the source material and the first reactant may be simultaneously supplied to the wafer 200 under the same processing conditions as those in steps A1 and A2 described above, thereby forming the SiO film in the recess by CVD. In this case, the thickness of the SiO film can be adjusted by adjusting the supply time of the source material and the first reactant. The supply time of the source material and the first reactant may be longer than the supply time of the source material and the first reactant in the processing conditions in steps A1 and A2 described above. The source material and the first reactant used in this method may be the same as the various source material and the first reactant exemplified in steps A1 and A2 described above.

[0068] Alternatively, in this step, the surface of the recess made of Si may be oxidized by thermal oxidation such as dry oxidation, wet oxidation, or reduced-pressure oxidation, or by plasma oxidation, ozone oxidation, or the like, to form an SiO film on the inner surface of the recess. For example, in this step, the wafer 200 may be subjected to the above-described step A2 alone under the same processing conditions as those in step A2 described above, thereby oxidizing the inner surface of the recess and forming an SiO film on the inner surface of the recess. In this case, the thickness of the SiO film can be adjusted by adjusting the supply time of the first reactant. Note that the supply time of the first reactant may be longer than the supply time of the first reactant in the processing conditions of step A2 described above. In this method, the first film-forming agent only needs to contain the first reactant. Furthermore, the first reactant used in this method may be the same as the various first reactants exemplified in step A2 described above.

[0069] The thickness of the SiO film formed in the recess in this step is preferably 5 nm or more, more preferably 10 nm or more, at the thinnest point of the SiO film. If the SiO film is less than 5 nm thick, it may not function as a modification stopper, as described below. By making the SiO film thicker than 5 nm, it is possible to obtain a sufficient function as a modification stopper. By making the SiO film thicker than 10 nm, it is possible to obtain a sufficient function as a modification stopper.

[0070] The thickness of the SiO film formed in the recess in this step is preferably a thickness that does not fill the opening of the recess, i.e., a thickness that leaves the opening of the recess. For example, if the recess is cylindrical, the thickness of the SiO film formed in the recess is preferably less than half the diameter of the opening of the recess. This is because if the opening of the recess is filled with the SiO film, it becomes difficult to form a SiN film as the second film.

[0071] The upper limit of the thickness of the SiO film formed in the recess may be determined depending on the size of the opening of the recess, but is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 15 nm or less. If the thickness of the SiO film exceeds 30 nm, the opening of the recess becomes narrow, and the filling characteristics of the SiN film may not be sufficiently obtained. By setting the thickness of the SiO film to 30 nm or less, this problem can be solved. By setting the thickness of the SiO film to 20 nm or less, this problem can be sufficiently solved. By setting the thickness of the SiO film to 15 nm or less, this problem can be more sufficiently solved.

[0072] From the above, the thickness of the SiO film formed in the recess in this step is preferably 5 nm to 30 nm, more preferably 5 nm to 20 nm, even more preferably 5 nm to 15 nm, and particularly preferably 10 nm to 15 nm.

[0073] The SiO film formed in this step has low reactivity with the modifying agent used in the subsequent step C, and has higher etching resistance than the modified layer formed in the subsequent step C.

[0074] (Step B) After step A is completed, step B is performed. In this step, a second film-forming agent is supplied to the wafer 200 in the processing chamber 201, thereby forming a SiN film as a second film on the SiO film as the first film formed in the recess in step A. In this step, a SiN film containing Si and nitrogen (N) is formed as the second film to a thickness sufficient to fill the recess whose inner surface has been formed with the SiO film. At this time, as shown in FIG. 5(b), the opening of the recess is blocked by the SiN film, and a portion not filled with the SiN film (a space caused by a void or seam) is formed in the recess. In other words, the SiN film formed to fill the recess has a space (a gap, a hollow portion) in the film. In this step, as shown in FIG. 5(b), a SiN film is also formed on the SiO film formed on the surface (upper surface) of the wafer 200 other than the recess.

[0075] In this step, for example, a SiN film is formed by alternately repeating a cycle of step B1 of supplying a raw material to the wafer 200 and step B2 of supplying a second reactant to the wafer 200 a predetermined number of times (n times, where n is an integer equal to or greater than 1). The method for forming a SiN film including steps B1 and B2 will be specifically described below. In the following example, the second film-forming agent includes the raw material and the second reactant.

[0076] [Step B1] In step B1, a raw material (raw material gas) is supplied as a second film forming agent to the wafer 200 in the processing chamber 201, i.e., the wafer 200 having an SiO film formed on the inner surface of the recess. This step can be performed using the same processing procedure as in step A1 described above and the following processing conditions. By this step, a Si-containing layer can be formed on the SiO film. After the Si-containing layer is formed, gases remaining in the processing chamber 201 are removed (purged) from the processing chamber 201 using the same processing procedure as in the purging in step A1 described above. As the raw material, for example, the same raw materials as those exemplified in step A1 described above can be used.

[0077] The processing conditions for supplying the raw material in step B1 are as follows: Treatment temperature: 400 to 800°C, preferably 500 to 650°C Treatment pressure: 1 to 2666 Pa, preferably 67 to 1333 Pa Raw material supply flow rate: 0.01 to 2 slm, preferably 0.1 to 1 slm Raw material supply time: 1 to 120 seconds, preferably 1 to 60 seconds Inert gas supply flow rate (per gas supply pipe): 0 to 10 slm is exemplified.

[0078] [Step B2] After step B1 is completed, a second reactant (second reaction gas) is supplied as a second film forming agent to the wafer 200 in the processing chamber 201, i.e., the wafer 200 on which the Si-containing layer is formed on the SiO film formed on the inner surface of the recess.

[0079] Specifically, valve 243c is opened to allow the second reactant to flow into gas supply pipe 232c. The flow rate of the second reactant flowing through gas supply pipe 232c is adjusted by MFC 241c, and the second reactant is supplied into processing chamber 201 via nozzle 249c and exhausted from exhaust port 231a. At this time, the second reactant is supplied to wafer 200 from the side of wafer 200. At this time, an inert gas may be supplied into processing chamber 201 via each of nozzles 249a to 249c.

[0080] The processing conditions for supplying the second reactant in step B2 are: Treatment temperature: 400 to 800°C, preferably 500 to 650°C Treatment pressure: 1 to 4000 Pa, preferably 1 to 3000 Pa Second reactant supply flow rate: 0.1~10slm Second reaction time: 1 to 120 seconds, preferably 1 to 60 seconds Inert gas supply flow rate (per gas supply pipe): 0 to 10 slm is exemplified.

[0081] Under the above-described processing conditions, at least a portion of the Si-containing layer is nitrided (modified) by supplying, for example, a nitriding agent (nitriding gas) as the second reactant to the wafer 200. As a result, a SiN layer is formed as a layer containing Si and N on the SiO film formed on the inner surface of the recess of the wafer 200. When the SiN layer is formed, impurities such as Cl contained in the Si-containing layer form a gaseous substance containing at least Cl during the modification reaction (nitridation reaction) of the Si-containing layer by the second reactant, and are exhausted from the processing chamber 201. As a result, the SiN layer contains fewer impurities such as Cl than the Si-containing layer formed in step B1.

[0082] After the SiN layer is formed, the valve 243c is closed to stop the supply of the second reactant into the processing chamber 201. Then, gases remaining in the processing chamber 201 are removed (purged) from the processing chamber 201 by a processing procedure similar to the purging in step A1.

[0083] As the second reactant (second reaction gas), which is one of the second film-forming agents, for example, a nitriding agent (nitriding gas) can be used. The nitriding agent can be used not only by being thermally excited in a non-plasma atmosphere, but also by being plasma-excited. That is, the nitriding agent can be used by being excited into a plasma state.

[0084] As the nitriding agent, for example, a nitrogen (N)-containing gas can be used. As the N-containing gas, an N- and H-containing gas can be used. As the N- and H-containing gas, for example, a hydrogen nitride gas such as ammonia (NH) gas, diazene (NH) gas, hydrazine (NH) gas, or NH gas can be used. Furthermore, as the N- and H-containing gas, for example, a C-, N-, and H-containing gas can be used. Examples of the C-, N-, and H-containing gas include ethylamine-based gases such as monoethylamine (C2H5NH2, abbreviated as MEA) gas, diethylamine ((C2H5)2NH, abbreviated as DEA) gas, and triethylamine ((C2H5)3N, abbreviated as TEA) gas; methylamine-based gases such as monomethylamine (CH3NH2, abbreviated as MMA) gas, dimethylamine ((CH3)2NH, abbreviated as DMA) gas, and trimethylamine ((CH3)3N, abbreviated as TMA) gas; and organic hydrazine-based gases such as monomethylhydrazine ((CH3)HN2H2, abbreviated as MMH) gas, dimethylhydrazine ((CH3)2N2H2, abbreviated as DMH) gas, and trimethylhydrazine ((CH3)2N2(CH3)H, abbreviated as TMH) gas. One or more of these can be used as the second reactant. When a second reactant containing C, such as an amine-based gas or an organic hydrazine-based gas, is used, a SiN layer containing C can be formed in step B2.

[0085] [Perform the specified number of times] By alternately performing the above-described steps B1 and B2, i.e., by performing the cycle non-simultaneously, a predetermined number of times (n times, where n is an integer equal to or greater than 1), the recesses of the wafer 200 can be filled with a SiN film as the second film, as shown in FIG. 5(b). The above-described cycle is preferably repeated multiple times. That is, it is preferable to make the thickness of the SiN layer formed per cycle thinner than the desired film thickness, and to repeat the above-described cycle multiple times until the thickness of the SiN film formed by stacking the SiN layers reaches a thickness that fills the recesses of the wafer 200.

[0086] In this step, a SiN film may be formed by a CVD method in which the source material and the second reactant are simultaneously supplied. For example, in this step, a SiN film may be formed in the recess by a CVD method by simultaneously supplying the source material and the second reactant to the wafer 200 under the same processing conditions as those in steps B1 and B2 described above. In this case, the thickness of the SiN film can be adjusted by adjusting the supply time of the source material and the second reactant. The supply time of the source material and the second reactant may be longer than the supply time of the source material and the second reactant under the processing conditions in steps B1 and B2 described above. The source material and the second reactant used in this method may be the same as the various source material exemplified in step A1 described above and the various second reactants exemplified in step B2 described above.

[0087] (Step C) After step B is completed, step C is performed. In this step, a F-containing modifying agent is supplied to the wafer 200 in the processing chamber 201 to modify a portion of the SiN film. Specifically, in this step, a portion of the front surface of the SiN film as the second film formed in step B is modified into an F-containing layer, particularly an F-containing SiO layer or SiOF layer as an F- and O-containing layer. The F-containing SiO layer or SiOF layer is also referred to as an Si, F, and O-containing layer. Since the F-containing SiO layer or SiOF layer is a modified portion of the SiN film, it will also be referred to as a modified layer hereinafter for convenience. By this step, as shown in FIG. 5(c), a modified layer is formed (laminate) on the SiN film, which remains unmodified, using the SiO film as a base, in the recess of the wafer 200. Note that in this step, the SiN film formed on the surface (upper surface) of the wafer 200 other than the recess is also modified into a modified layer, as shown in FIG. 5(c).

[0088] Specifically, the valve 243d is opened to allow the modifying agent to flow into the gas supply pipe 232d. The modifying agent flowing through the gas supply pipe 232d has its flow rate adjusted by the MFC 241d, is supplied into the processing chamber 201 via the nozzle 249a, and is exhausted from the exhaust port 231a. At this time, the modifying agent is supplied onto the wafer 200 from the side of the wafer 200. At this time, an inert gas may be supplied into the processing chamber 201 via each of the nozzles 249a to 249c.

[0089] The processing conditions for supplying the modifying agent in step C are as follows: Treatment temperature: 100 to 500°C, preferably 350 to 450°C Treatment pressure: 1 to 2666 Pa, preferably 67 to 1333 Pa Modifier supply flow rate: 0.001 to 2 slm, preferably 0.002 to 1 slm Modifier supply time: 30 seconds to 30 minutes, preferably 1 minute to 20 minutes Inert gas supply flow rate (per gas supply pipe): 0 to 10 slm is exemplified.

[0090] By supplying the wafer 200 with a modifier containing F under the above-described processing conditions, a portion of the SiN film embedded in the recess is modified into a modified layer (an F-containing SiO layer or SiOF layer). The modification of the SiN film into a modified layer progresses from the surface of the SiN film in the depth direction as the modifier is supplied to the SiN film surface, so that the SiN film located on the surface side (the upper side in FIG. 5(c)) of the SiN film in the recess is converted into a modified layer (an F-containing SiO layer or SiOF layer). The thickness of the modified layer can be controlled by the conditions for supplying the modifier to the wafer 200.

[0091] In this step, the SiO film formed as the first film in step A can be made to function as a modification-suppressing film. This makes it possible to suppress modification of the SiO film by the modifying agent, even when modifying a portion of the SiN film from the surface of the SiN film to the portion where the SiN film contacts a portion of the SiO film. In other words, the SiO film formed in step A can suppress or stop the progress of modification of the SiO film itself by the modifying agent in the depth direction. In other words, the SiO film functions as a modification stopper. This makes it possible to prevent alteration or damage to the inner surfaces of the recesses of the wafer 200, which are the base of the SiO film, during the execution of this step.

[0092] The reason why the SiO film functions as a modification stopper is because the reactivity of the modifier with the SiO film is lower than that of the SiN film. In other words, the modifier is a substance whose reactivity with the SiO film is lower than that of the SiN film. In other words, the modifier is supplied under processing conditions that make the reactivity of the modifier with the SiO film lower than that of the SiN film. By utilizing this difference in reactivity, this step makes it possible to selectively modify a portion of the SiN film while suppressing or stopping the progress of the modification of the SiO film. Depending on the processing conditions, it is also possible to prevent the modifier from reacting with the SiO film, i.e., to prevent the SiO film from being modified.

[0093] As a result, in this step, the modification of the SiN film can be carried out directionally and selectively in the depth direction within the recess, and a modified layer having the shape shown in Fig. 5(c) can be formed. As a result, a laminated film is present in the recess, in which the modified layer (F-containing SiO layer or SiOF layer) is laminated on the SiN film, which is maintained without being modified, based on the SiO film.

[0094] In this step, it is preferable to modify the region of the SiN film from the surface of the SiN film to a portion that contacts at least a portion of the space (void or seam) generated during the formation of the SiN film. That is, in this step, it is preferable to proceed with the modification of the SiN film to a position deeper than the top of the space (void or seam) in the SiN film. For example, it is preferable to proceed with the modification of the SiN film to a position at least halfway through the depth of the space in the SiN film. It is more preferable, for example, to proceed with the modification of the SiN film to a position exceeding halfway through the depth of the space in the SiN film. It is even more preferable, for example, to proceed with the modification of the SiN film to a position at least two-thirds through the depth of the space in the SiN film. Note that FIG. 5(c) shows an example in which the modification of the SiN film has proceeded to a position at least two-thirds through the depth of the space in the SiN film.

[0095] By progressing the modification of the SiN film in this manner, it is possible to eliminate at least a portion of the space in the SiN film in the recess by removing the modified layer in step D, which is performed later, and to open the space. As a result, the space in the recess can be filled with a third film formed in step E, which is performed after step D. It is also possible to progress the modification of the SiN film to the same depth as the bottom of the space in the SiN film. In this case, it is possible to eliminate the space itself in the SiN film by removing the modified layer in step D, which is performed later.

[0096] In this way, in this step, the SiO film functions as a modification stopper, making it possible to selectively modify a portion of the SiN film without altering or damaging the inner surface of the recess made of Si or the like.

[0097] After the modified layer is formed, the valve 243d is closed to stop the supply of the modifying agent into the processing chamber 201. Then, gases remaining in the processing chamber 201 are removed (purged) from the processing chamber 201 by a processing procedure similar to the purging in step A1.

[0098] As the modifier (modifying gas), for example, a substance containing F is preferably used, a substance containing F and O is more preferably used, and a substance containing F, O, and N is even more preferably used. Furthermore, as the modifier, for example, an F-containing gas is preferably used, a gas containing F and O is more preferably used, and a gas containing F, O, and N is even more preferably used. That is, the modifier preferably contains F, more preferably contains F and O, and even more preferably contains F, O, and N. Furthermore, as the modifier, for example, a mixed gas of an N- and O-containing gas and an F-containing gas, a mixed gas of an F-, N-, and O-containing gas and an F-containing gas, or an F-, N-, and O-containing gas can also be used. By using such a modifier, it is possible to modify a part of the SiN film as the second film into a layer (an F-containing SiO layer or an SiOF layer) that is easily removed by an etching agent.

[0099] Examples of modifiers that can be used include NO gas + fluorine (F2) gas, NO gas + chlorine monofluoride (ClF) gas, NO gas + chlorine trifluoride (ClF3) gas, NO gas + nitrogen trifluoride (NF3) gas, nitrosyl fluoride (FNO) gas + F2 gas, FNO gas + ClF gas, FNO gas + ClF3 gas, FNO gas + NF3 gas, and FNO gas. One or more of these can be used as the modifier. For example, gases that are difficult to store, such as FNO gas, are preferably generated by mixing F2 gas and NO gas in a supply pipe or nozzle, and then supplied into the processing chamber 201. In this case, a mixed gas of F2 gas, NO gas, and FNO gas is supplied into the processing chamber 201.

[0100] (Step D) After step C is completed, step D is performed. In this step, a halogen-containing etchant is supplied to the wafer 200 in the processing chamber 201 to remove the modified portion (modified layer) of the SiN film. That is, in this step, the portion (modified layer) of the SiN film that was modified into an F-containing SiO layer or an SiOF layer in step C is removed. By this step, as shown in FIG. 5(d), the SiN film remains unmodified in the recess of the wafer 200, exposing the surface of the SiN film and a portion of the SiO film, i.e., the portion that was in contact with the modified layer, is exposed. Note that in this step, the modified layer on the surface (upper surface) of the wafer 200 other than the recess is also removed, exposing the SiO film, as shown in FIG. 5(d).

[0101] Specifically, the valve 243e is opened to allow the etching agent to flow into the gas supply pipe 232e. The flow rate of the etching agent is adjusted by the MFC 241e, and the etching agent is supplied into the processing chamber 201 via the gas supply pipe 232b and the nozzle 249b, and is exhausted from the exhaust port 231a. At this time, the etching agent is supplied onto the wafer 200 from the side of the wafer 200. At this time, an inert gas may be supplied into the processing chamber 201 via each of the nozzles 249a to 249c.

[0102] The processing conditions for supplying the etching agent in step D are as follows: Treatment temperature: room temperature (25°C) to 600°C, preferably 50 to 200°C Treatment pressure: 1 to 13332 Pa, preferably 100 to 1333 Pa Etching agent supply flow rate: 0.05 to 5 slm, preferably 0.1 to 2 slm Etching agent supply time: 0.1 to 30 minutes, preferably 1 to 10 minutes Inert gas supply flow rate (per gas supply pipe): 0 to 10 slm is exemplified.

[0103] By supplying an etching agent to the wafer 200 under the above-described processing conditions, the modified portion of the SiN film, i.e., the modified layer (F-containing SiO layer or SiOF layer), is removed. At this time, the SiO film formed in step A can function as an etching suppression film, and even when etching the modified layer in contact with the SiO film, the SiO film can be suppressed from being etched. That is, the SiO film can suppress or stop the progression of etching in the depth direction of the SiO film, i.e., toward the underlying layer of the SiO film. In other words, the SiO film functions as an etching stopper. As a result, it is possible to prevent the inner surfaces of the recesses of the wafer 200, which are the underlying layer of the SiO film, from being altered or damaged during this step.

[0104] The SiO film functions as an etching stopper because the reactivity of the etchant with the SiO film is lower than that of the modified layer (F-containing SiO layer or SiOF layer). In other words, the etchant is a substance whose reactivity with the SiO film is lower than that of the modified layer. In other words, the etchant is supplied under processing conditions in which the reactivity of the etchant with the SiO film is lower than that of the modified layer. By utilizing this difference in reactivity, this step makes it possible to selectively etch the modified layer while suppressing or stopping the etching of the SiO film. The SiO film is a non-F-containing film, whereas the modified layer is an F-containing layer. This difference in chemical composition between the SiO film and the modified layer is one of the reasons why the etching rate of the SiO film is lower than that of the modified layer, i.e., why the etching resistance of the SiO film is higher than that of the modified layer.

[0105] As a result, in this step, etching of the portion of the SiN film that has been modified into an F-containing SiO layer or an SiOF layer, i.e., the modified layer, can be advanced directionally and selectively in the depth direction within the recess. As a result, as shown in Figure 5(d), the SiN film remains unmodified on the SiO film as an underlayer within the recess, and the portion of the SiO film that was in contact with the modified layer is exposed.

[0106] After removing the modified layer and exposing the surface of the SiN film that remains unmodified, the valve 243e is closed to stop the supply of the etching agent into the processing chamber 201. Then, the processing chamber 201 is evacuated to remove gaseous substances and the like remaining in the processing chamber 201. Then, the gaseous substances and the like remaining in the processing chamber 201 are removed (purged) from the processing chamber 201 by the same processing procedure as the purging in step A1 described above.

[0107] The etching agent (etching gas) is preferably a substance containing halogen, for example, a substance containing at least one of F, Cl, and I. This makes it possible to effectively suppress etching of the SiO film as the first film while selectively removing the modified portion (modified layer) of the SiN film as the second film.

[0108] Examples of the etching agent that can be used include F2 gas, NF3 gas, ClF3 gas, ClF gas, tungsten hexafluoride (WF6) gas, iodine heptafluoride (IF7) gas, iodine pentafluoride (IF5) gas, hexafluoroacetylacetone (C5H2F6O2) gas, hydrogen fluoride (HF) gas, FNO gas, chlorine (Cl2) gas, hydrogen chloride (HCl) gas, boron trichloride (BCl3) gas, thionyl chloride (SOCl2) gas, tungsten hexachloride (WCl6) gas, etc. One or more of these can be used as the etching agent.

[0109] The modifying agent used in step C and the etching agent used in step D may be the same substance (gas). For example, FNO gas, for example, may be used as the modifying agent in step C, and FNO gas, for example, may be used as the etching agent in step D. In this case, by controlling the processing conditions for steps C and D, it is possible to make the FNO gas act as the modifying agent in step C and the FNO gas act as the etching agent in step D.

[0110] (Step E) After step D is completed, step E is executed. In this step, a third film-forming agent is supplied to the wafer 200 in the processing chamber 201, thereby forming a SiN film as a third film on the SiN film after the modified layer has been removed. In this step, a SiN film as a third film is formed on the SiN film (the SiN film that remains without being modified) that has been removed in step D and remains in the recess, as shown in FIG. 5(e), to a thickness that fills the recess. In this step, as shown in FIG. 5(e), a SiN film is also formed on the surface of the wafer 200 other than the recess.

[0111] At the end of step D, the SiN film as the second film remains unmodified on the bottom side of the recess in wafer 200. This relaxes (reduces) the depth of the recess (trench or hole), i.e., the aspect ratio, and makes it possible to fill the recess without generating voids or seams even if a SiN film as the third film is formed to a thickness that fills the recess.

[0112] In this step, a SiN film can be formed as the third film-forming agent using the same raw material and second reactant as the second film-forming agent in the above-mentioned step B, and using the same processing procedure and processing conditions as those in the above-mentioned step B. As the raw material, for example, the same raw material as the various raw materials exemplified in the above-mentioned step B1 (step A1) can be used, and as the second reactant, for example, the same second reactant as the various second reactants exemplified in the above-mentioned step B2 can be used.

[0113] (After purging and atmospheric pressure recovery) After step E is completed, an inert gas is supplied as a purge gas from each of the nozzles 249a to 249c into the processing chamber 201 and exhausted from the exhaust port 231a. This purges the processing chamber 201, and gases and reaction by-products remaining in the processing chamber 201 are removed from the processing chamber 201 (after-purge). Thereafter, the atmosphere in the processing chamber 201 is replaced with the inert gas (inert gas replacement), and the pressure in the processing chamber 201 is returned to normal pressure (atmospheric pressure return).

[0114] (Boat unloading and wafer discharge) Thereafter, the seal cap 219 is lowered by the boat elevator 115, and the lower end of the manifold 209 is opened. Then, the processed wafers 200, supported by the boat 217, are unloaded from the lower end of the manifold 209 to the outside of the reaction tube 203 (boat unloading). After the boat unloading, the shutter 219s is moved, and the opening at the lower end of the manifold 209 is sealed by the shutter 219s via the O-ring 220c (shutter close). After being unloaded to the outside of the reaction tube 203, the processed wafers 200 are removed from the boat 217 (wafer discharge).

[0115] It is preferable to perform steps A, B, C, D, and E in the same processing chamber (in-situ), which allows steps A, B, C, D, and E to be performed without exposing the wafer 200 to the atmosphere, i.e., while keeping the surface of the wafer 200 clean.

[0116] (3) Effects of this mode According to this aspect, one or more of the following effects can be obtained.

[0117] In this embodiment, a first film is formed in a recess on the surface of the wafer 200 in step A before a second film is formed in step B. This allows the first film to function as a modification-suppressing film when a portion of the second film is modified in step C, and also as an etching-suppressing film when the modified portion of the second film (modified layer) is removed in step D. That is, the first film formed in the recess before the second film is formed functions as a modification stopper when a portion of the second film is modified, and also as an etching stopper when the modified portion of the second film (modified layer) is removed. This allows the second film to be modified and the modified portion of the second film (modified layer) to be removed without altering or damaging the inner surface of the recess. As a result, a film can be formed in the recess with high precision.

[0118] In this embodiment, in step E, a third film can be formed in a recess having an inner surface that is maintained in an appropriate state without being altered or damaged. This allows a film to be formed in the recess with high precision. As a result, the recess can be filled with a film with high precision. Note that by making the material of the third film the same as that of the second film, it is possible to fill the recess with a film of the same material. Furthermore, by making the material of the third film different from that of the second film, it is possible to fill the recess with a film (stacked film) of a different material.

[0119] In this embodiment, an SiO film, which is an oxide film, is formed as the first film in step A. Since the first film is an oxide film in this way, the first film can function effectively as a modification stopper when a portion of the SiN film serving as the second film is modified in step C, and the first film can function effectively as an etching stopper when the modified portion (modified layer) of the SiN film is removed in step D. Furthermore, since the first film is an SiO film, the first film can function more effectively as a modification stopper when a portion of the SiN film serving as the second film is modified in step C, and the first film can function more effectively as an etching stopper when the modified portion (modified layer) of the SiN film is removed in step D.

[0120] In this embodiment, a film other than an SiO film, i.e., a SiN film having a chemical composition different from that of an SiO film, is formed as the second film in step B. By using a film other than an SiO film, i.e., a film having a chemical composition different from that of an SiO film, particularly a SiN film, as the second film, it becomes possible to make the second film a film that is easily modified by a modifying agent and difficult to remove by an etching agent.

[0121] In this embodiment, a wafer 200 is used in which the surface of the recess is made of a material other than an SiO film, i.e., Si, which is a material with a different chemical composition from an SiO film. By making the surface of the recess in this way of a material other than an SiO film, i.e., a material with a different chemical composition from an SiO film, particularly a material containing Si, it becomes possible to produce the above-mentioned effect more remarkably.

[0122] In this embodiment, the reactivity of the modifier with the first film is set to be lower than the reactivity of the modifier with the second film. That is, the reactivity of the modifier with the second film is set to be higher than the reactivity of the modifier with the first film. This makes it possible to selectively modify a portion of the second film while suppressing modification of the first film in step C.

[0123] In this embodiment, in step C, a portion of the second film from the surface of the second film to the portion where it contacts a portion of the first film is modified, and in step D, a portion of the first film is exposed. By performing steps C and D, it is possible to selectively modify a portion of the second film while suppressing modification of the first film, and to selectively remove the modified portion of the second film (modified layer) while suppressing etching of the first film.

[0124] In this embodiment, the second film has a seam or a void, and in step C, a region of the second film from the surface of the second film to a portion that contacts at least a portion of the seam or the void is modified, and in step D, the modified region (modified layer) is removed while at least a portion of the seam or the void is eliminated. By eliminating at least a portion of the seam or the void in the second film in this manner, it becomes possible to fill the recess seamlessly and void-free.

[0125] In this embodiment, in step C, a portion of the second film is modified into an F- and O-containing layer, particularly a Si-, F-, and O-containing layer. This allows the portion of the second film to be modified into a layer that is easily removed by an etching agent, and makes it possible to effectively selectively remove the modified portion of the second film while suppressing etching of the first film.

[0126] In this embodiment, the reactivity of the etching agent with the first film is set lower than the reactivity of the etching agent with the modified portion (modified layer) of the second film. That is, the reactivity of the etching agent with the modified layer is set higher than the reactivity of the etching agent with the first film. This makes it possible to selectively remove the modified portion of the second film while suppressing etching of the first film.

[0127] (4) Variations The processing sequence in this embodiment can be modified as shown in the following modified examples. These modified examples can be combined as desired. Unless otherwise specified, the processing procedures and processing conditions in each step of each modified example can be the same as the processing procedures and processing conditions in each step of the above-described processing sequence.

[0128] (Variation 1) As in the processing sequence shown below, the cycle of step C → step D may be performed multiple times (y times, where y is an integer of 2 or more).

[0129] Step A → Step B → (Step C → Step D) × y → Step E

[0130] This modification also provides the same effects as those of the above-described embodiment. Furthermore, according to this modification, even if the etching amount (removal amount) of the SiN film formed in step B is insufficient after steps C and D are completed, the etching amount can be increased by repeating the cycle of step C → step D multiple times. Furthermore, in this case, the etching amount can be controlled by the number of cycles (y), and the controllability of the etching amount can also be improved. According to this modification, even in such a case, the filling can be performed while controlling the etching amount, and void-free and seamless filling can be achieved.

[0131] (Variation 2) As in the processing sequence shown below, the cycle of step C → step D → step E may be performed multiple times (z times, where z is an integer of 2 or more).

[0132] Step A → Step B → (Step C → Step D → Step E) × z

[0133] This modification also provides the same effects as the above-described embodiment. Furthermore, according to this modification, even if voids or seams (spaces) occur in the SiN film serving as the third film formed in step E, for example, when the recess is deep (having a large aspect ratio), the recess can be filled while eliminating the voids or seams by repeating the cycle of step C → step D → step E multiple times. According to this modification, even in such a case, void-free and seamless filling is possible.

[0134] (Variation 3) The material of the third film formed in step E may be different from the material of the second film formed in step B. By differentiating the material of the third film from the material of the second film, it is possible to fill the recess with a film (stacked film) made of a different material. In this case, the third film can be formed by using a film-forming agent (second source material, second reactant) different from the second film-forming agent used in step B as the third film-forming agent (third source material, third reactant) used in step E, and selecting a processing procedure and processing conditions according to the material of the third film. In this case, by making at least one of the source material and the reactant different between step E and step B, the material of the third film can be made different from the material of the second film. In this modification, it is also possible to form a film in the recess with high precision.

[0135] <Other Aspects of the Present Disclosure> Although the embodiments of the present disclosure have been specifically described above, the present disclosure is not limited to the above embodiments and can be modified in various ways without departing from the spirit and scope of the present disclosure.

[0136] For example, in the above-described embodiments and modifications, examples in which steps A, B, C, D, and E are performed have been described, but step E in the above-described embodiments may be omitted, as in the processing sequence shown below. For example, if it is not necessary to fill the recess with a third film in step E, step E can be omitted. In this embodiment as well, it is possible to form a film in the recess with high precision.

[0137] Step A → Step B → Step C → Step D Step A → Step B → (Step C → Step D) × y

[0138] Furthermore, for example, in the above-described embodiments and modifications, examples have been described in which steps A, B, C, D, and E are performed (in-situ) within the same processing chamber 201, but at least one of steps A, B, C, D, and E may be performed (ex-situ) within a different processing chamber (processing section, processing space). If at least one of steps A, B, C, D, and E is performed within a separate processing chamber, the temperature within each processing chamber can be set in advance to, for example, the processing temperature for each step or a temperature close to that temperature, thereby shortening the time required for temperature adjustment and improving production efficiency.

[0139] Furthermore, for example, in the above-described embodiments and modifications, examples have been described in which the surface of the recess is made of Si, but the surface of the recess may be made of a material having a different chemical composition from that of the first film, for example, a material containing Si. For example, the surface of the recess may be made of at least one of single crystal Si, a Si film, a SiN film, a silicon carbide film (SiC film), a silicon carbonitride film (SiCN film), a silicon oxycarbonitride film (SiOCN film), a silicon oxycarbonide film (SiOCN film), a silicon oxynitride film (SiON film), a silicon borocarbonitride film (SiBCN film), a silicon boronitride film (SiBN), a silicon borocarbide film (SiBC film), and a silicon boronoxide film (SiBO film).

[0140] Furthermore, for example, in the above-described embodiments and modifications, examples have been described in which the second film and the third film are SiN films, but the second film and the third film may be films other than SiO films, and may be, for example, films containing Si and N. For example, the second film and the third film may include at least one of a SiN film, a SiCN film, a SiOCN film, a SiOCN film, a SiON film, a SiBCN film, and a SiBN film.

[0141] It is preferable that the recipes used for each process are individually prepared according to the process content and stored in the storage device 121c via an electric communication line or an external storage device 123. Then, when starting each process, it is preferable that the CPU 121a appropriately selects an appropriate recipe according to the process content from among the multiple recipes stored in the storage device 121c. This makes it possible to reproducibly form films with various film types, composition ratios, film qualities, and film thicknesses using a single substrate processing device. It also reduces the burden on the operator, prevents operational errors, and enables each process to be started quickly.

[0142] The above-mentioned recipes do not necessarily have to be newly created, but may be prepared by modifying an existing recipe already installed in the substrate processing apparatus, for example. When modifying a recipe, the modified recipe may be installed in the substrate processing apparatus via an electric communication line or a recording medium on which the modified recipe is recorded. Alternatively, an existing recipe already installed in the substrate processing apparatus may be directly modified by operating the input / output device 122 provided in the existing substrate processing apparatus.

[0143] 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 has been described. The present disclosure is not limited to the above-described embodiment and can be suitably applied, for example, to a case where a film is formed using a single-wafer substrate processing apparatus that processes one or several substrates at a time. Furthermore, in the above-described embodiment, an example of forming a film using a substrate processing apparatus having a hot-wall processing furnace has been described. The present disclosure is not limited to the above-described embodiment and can be suitably applied to a case where a film is formed using a substrate processing apparatus having a cold-wall processing furnace.

[0144] When using these substrate processing apparatuses, each process can be performed using the same processing procedures and conditions as in the above-described embodiments and modifications, and the same effects as in the above-described embodiments and modifications can be obtained.

[0145] The above-described embodiments and modifications may be used in combination as appropriate. The processing procedures and processing conditions in such a case may be the same as those in the above-described embodiments and modifications, for example. [Explanation of symbols]

[0146] 200 wafers (substrates)

Claims

1. a step of preparing a substrate on which the following steps have been performed: (a) supplying a first film-forming agent to a substrate having a recess on its surface to form a first film in the recess; and (b) supplying a second film-forming agent to the substrate to form a second film on the first film formed in the recess, the second film having a chemical composition different from that of the first film. (c) modifying a portion of the second film by supplying a modifying agent containing fluorine and oxygen to the substrate; (d) removing the modified portion of the second film by supplying an etching agent containing a halogen to the substrate; A substrate processing method comprising:

2. 2. The substrate processing method according to claim 1, further comprising the step of: (e) supplying a third film-forming agent to the substrate to form a third film on the second film after removing the modified portion.

3. 2. The substrate processing method according to claim 1, wherein the first film is an oxide film.

4. 2. The substrate processing method according to claim 1, wherein the first film is a silicon oxide film.

5. 2. The substrate processing method according to claim 1, wherein the second film is a film other than a silicon oxide film.

6. 2. The substrate processing method according to claim 1, wherein the second film is a film containing silicon and nitrogen.

7. 2. The substrate processing method according to claim 1, wherein the surface of the recess is made of a material other than silicon oxide.

8. The substrate processing method according to claim 1 , wherein the surface of the recess is made of a material containing silicon.

9. 2. The substrate processing method according to claim 1, wherein the modifying agent contains fluorine, nitrogen, and oxygen.

10. 2. The substrate processing method according to claim 1, wherein the modifying agent is a mixed gas of a nitrogen- and oxygen-containing gas and a fluorine-containing gas, a mixed gas of a fluorine-, nitrogen- and oxygen-containing gas and a fluorine-containing gas, or a fluorine-, nitrogen- and oxygen-containing gas.

11. 2. The substrate processing method according to claim 1, wherein the reactivity of the modifying agent with the first film is lower than the reactivity of the modifying agent with the second film.

12. 2. The substrate processing method of claim 1, wherein (c) modifies a portion of the second film from the surface of the second film to the point where the second film contacts a portion of the first film, and (d) exposes a portion of the first film.

13. the second film has a seam or a void; 2. The substrate processing method of claim 1, wherein (c) modifies a region of the second film from the surface of the second film to a point that contacts at least a portion of the seam or void, and (d) eliminates at least a portion of the seam or void.

14. 2. The substrate processing method according to claim 1, wherein in step (c), a part of the second film is modified into a layer containing fluorine and oxygen.

15. 2. The substrate processing method according to claim 1, wherein in step (c), a part of the second film is modified into a layer containing silicon, fluorine, and oxygen.

16. 2. The substrate processing method according to claim 1, wherein the etching agent is a substance containing at least one of fluorine, chlorine, and iodine.

17. 2. The substrate processing method according to claim 1, wherein the reactivity of the etching agent with the first film is lower than the reactivity of the etching agent with the modified portion of the second film.

18. a step of preparing a substrate on which the following steps have been performed: (a) supplying a first film-forming agent to a substrate having a recess on its surface to form a first film in the recess; and (b) supplying a second film-forming agent to the substrate to form a second film on the first film formed in the recess, the second film having a chemical composition different from that of the first film. (c) modifying a portion of the second film by supplying a modifying agent containing fluorine and oxygen to the substrate; (d) removing the modified portion of the second film by supplying an etching agent containing a halogen to the substrate; A method for manufacturing a semiconductor device having the above structure.

19. a modifying agent supply system that supplies a modifying agent containing fluorine and oxygen to the substrate; an etching agent supply system for supplying an etching agent containing a halogen to the substrate; a control unit configured to be able to control the operation of a substrate processing apparatus to perform the following processes: (a) a process of supplying a first film-forming agent to a substrate having a recess on its surface to form a first film in the recess; (b) a process of supplying a second film-forming agent to the substrate to form a second film on the first film formed in the recess, the second film having a chemical composition different from that of the first film; (c) a process of supplying the modifying agent to the substrate to modify a portion of the second film; and (d) a process of supplying the etching agent to the substrate to remove the modified portion of the second film. A substrate processing apparatus having:

20. a step of preparing a substrate on which the following steps have been performed: (a) supplying a first film-forming agent to a substrate having a recess on its surface to form a first film in the recess; and (b) supplying a second film-forming agent to the substrate to form a second film on the first film formed in the recess, the second film having a chemical composition different from that of the first film; (c) modifying a portion of the second film by supplying a modifying agent containing fluorine and oxygen to the substrate; (d) removing the modified portion of the second film by supplying an etching agent containing a halogen to the substrate; A program that causes a computer to execute the above in a substrate processing apparatus.

Images