Substrate processing method, semiconductor device manufacturing method, substrate processing system, and recording medium

Abstract

The present invention relates to a semiconductor device manufacturing method, a substrate processing method, a substrate processing system, and a recording medium. The characteristics of a film formed on a substrate are improved. The method includes: (a) a step of forming a first film in an amorphous state on the substrate by supplying a first processing gas to the substrate; (b) a step of forming a second film in an amorphous state on the first film, the second film having a lower crystallization temperature than the first film, by supplying a second processing gas to the substrate; (c) a step of crystallizing the first film and the second film formed on the substrate by heating; and (d) a step of removing at least the second film by exposing the surface of the substrate to an etchant after crystallizing the first film and the second film.

Description

Technical Field

[0001] This invention relates to substrate processing methods, semiconductor device manufacturing methods, substrate processing systems, and recording media. Background Technology

[0002] As a step in the manufacturing process of semiconductor devices, there is a process of forming a film on a substrate (see, for example, Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-135344 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The purpose of this invention is to provide a technique for forming high-quality films on a substrate.

[0008] Methods for solving problems

[0009] According to one aspect of the present invention, a technique for performing the following steps is provided:

[0010] (a) A step of forming an amorphous first film on the substrate by supplying a first processing gas to the substrate.

[0011] (b) A process of forming a second film in an amorphous state with a crystallization temperature lower than that of the first film on the first film by supplying a second processing gas to the substrate.

[0012] (c) A process of crystallizing the first film and the second film formed on the substrate by heating, and

[0013] (d) The process of removing at least the second film by exposing the surface of the substrate to an etchant after crystallizing the first film and the second film.

[0014] Invention Effects

[0015] According to the present invention, a high-quality film can be formed on a substrate. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a vertical processing furnace for a substrate processing system suitably used in various embodiments of the present invention, and a diagram showing the furnace portion in a longitudinal sectional view.

[0017] Figure 2This is a schematic diagram of a vertical processing furnace for a substrate processing system suitably used in various embodiments of the present invention, and is intended to be... Figure 1 The diagram shows the processing furnace section using an AA-line sectional view.

[0018] Figure 3 This is a schematic diagram of the controller of a substrate processing system suitably used in various embodiments of the present invention, and a block diagram showing the control system of the controller.

[0019] Figure 4 (a) is a partially enlarged cross-sectional view of the wafer surface before film deposition, in the substrate processing sequence of the first embodiment of the present invention. Figure 4 (b) is a partially enlarged cross-sectional view of the wafer surface after the seed layer is formed, showing the substrate processing sequence in the first aspect of the present invention. Figure 4 (c) is a partially enlarged cross-sectional view of the wafer surface after the formation of the first film, showing the substrate processing sequence in the first aspect of the present invention. Figure 4 (d) is a partially enlarged cross-sectional view of the wafer surface after the formation of the second film, in the substrate processing sequence of the first embodiment of the present invention. Figure 4 (e) is a partially enlarged cross-sectional view of the crystallized wafer surface, showing the substrate processing sequence in the first aspect of the present invention. Figure 4 (f) is a partially enlarged cross-sectional view of the substrate processing sequence in the first aspect of the present invention on the surface of the modified wafer; Figure 4 (g) is a partially enlarged cross-sectional view of the substrate processing sequence in the first aspect of the present invention on the surface of the etched wafer.

[0020] Figure 5 (a) is a partially enlarged cross-sectional view of the wafer surface before film deposition, in a modified example of the first aspect of the present invention, showing the substrate processing sequence. Figure 5 (b) is a partially enlarged cross-sectional view of the wafer surface after the seed layer is formed, showing the substrate processing sequence in a modified example of the first aspect of the present invention. Figure 5 (c) is a partially enlarged cross-sectional view of the wafer surface after the formation of the first film, showing the substrate processing sequence in a variation of the first aspect of the present invention. Figure 5 (d) is a partially enlarged cross-sectional view of the wafer surface after the formation of the second film, in a modified example of the first aspect of the present invention, showing the substrate processing sequence. Figure 5 (e) is a partially enlarged cross-sectional view of the substrate processing sequence on the surface of the crystallized wafer in a modified example of the first aspect of the present invention; Figure 5 (f) is a partially enlarged cross-sectional view of the substrate processing sequence on the etched wafer surface in a variation of the first aspect of the present invention.

[0021] Figure 6 (a) is a partially enlarged cross-sectional view of the wafer surface before film deposition, in the substrate processing sequence of the second aspect of the present invention. Figure 6 (b) is a partially enlarged cross-sectional view of the wafer surface after the seed layer is formed, showing the substrate processing sequence in the second aspect of the present invention. Figure 6 (c) is a partially enlarged cross-sectional view of the wafer surface after the formation of the first film, in the substrate processing sequence of the second aspect of the present invention. Figure 6 (d) is a partially enlarged cross-sectional view of the wafer surface after the formation of the second film, showing the substrate processing sequence in the second aspect of the present invention. Figure 6 (e) is a partially enlarged cross-sectional view of the substrate processing sequence in the second aspect of the present invention on the surface of the crystallized wafer; Figure 6 (f) is a partially enlarged cross-sectional view of the substrate processing sequence in the second aspect of the present invention on the surface of the modified wafer; Figure 6 (g) is a partially enlarged cross-sectional view of the substrate processing sequence in the second aspect of the present invention on the surface of the etched wafer.

[0022] Figure 7 (a) is a partially enlarged cross-sectional view of the wafer surface before film deposition, in a modified example of the second aspect of the present invention, showing the substrate processing sequence. Figure 7 (b) is a partially enlarged cross-sectional view of the wafer surface after the seed layer is formed, showing the substrate processing sequence in a modified example of the second aspect of the present invention. Figure 7 (c) is a partially enlarged cross-sectional view of the wafer surface after the formation of the first film, showing the substrate processing sequence in a modified example of the second aspect of the present invention. Figure 7 (d) is a partially enlarged cross-sectional view of the wafer surface after the formation of the second film, showing the substrate processing sequence in a modified example of the second aspect of the present invention. Figure 7 (e) is a partially enlarged cross-sectional view of the substrate processing sequence on the surface of the crystallized wafer in a modified example of the second aspect of the present invention; Figure 7 (f) is a partially enlarged cross-sectional view of the substrate processing sequence on the etched wafer surface in a variation of the second aspect of the present invention.

[0023] Figure 8 (a) is a schematic diagram illustrating one approach to a substrate processing system using an intermittent substrate processing apparatus; Figure 8 (b) is a schematic diagram illustrating another mode of substrate processing system when using an intermittent substrate processing apparatus.

[0024] Figure 9 This is a schematic diagram illustrating one approach to a substrate processing system using a monolithic cluster substrate processing apparatus.

[0025] Figure 10 The graphs show the evaluation results for Example 1 and Comparative Example 1, respectively.

[0026] Figure 11 The graphs show the evaluation results for Example 2 and Comparative Example 2, respectively. Detailed Implementation

[0027] <First aspect of the present invention>

[0028] The following mainly refers to Figures 1-3 , Figure 4 (a)~ Figure 4 (g) will describe the first aspect of the present invention. It should be noted that the drawings used in the following description are schematic, and the dimensional relationships and ratios of the elements shown in the drawings may not be consistent with the actual situation. Furthermore, the dimensional relationships and ratios of the elements may not be consistent between the various drawings.

[0029] (1) Composition of substrate processing device

[0030] like Figure 1 As shown, the processing furnace 202 has a heater 207 that functions as a temperature regulator (heating unit). The heater 207 is cylindrical and is vertically assembled by being supported on a retaining plate. The heater 207 also functions as an activation mechanism (excitation unit) that activates (excites) the gas by heat.

[0031] A reaction tube 203 is arranged 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 is formed into a cylindrical shape with a closed upper end and an open lower end. Below the reaction tube 203, a manifold 209 is arranged concentrically with the reaction tube 203. The manifold 209 is made of a metal material such as stainless steel (SUS) and is formed into a cylindrical shape with open upper and lower ends. The upper end of the manifold 209 is configured to engage with and support the lower end of the reaction tube 203. An O-ring 220a is provided between the manifold 209 and the reaction tube 203 as a sealing component. The reaction tube 203 is also vertically assembled with the heater 207. The processing container (reaction container) is mainly composed of the reaction tube 203 and the manifold 209. A processing chamber 201 is formed in the hollow portion of the processing container. The processing chamber 201 is configured to accommodate a wafer 200, which serves as a substrate. Processing of the wafer 200 is performed within the processing chamber 201.

[0032] Inside the processing chamber 201, nozzles 249a to 249c, serving as the first to third supply units, are respectively installed through the side wall of the manifold 209. These nozzles are also referred to as the first nozzle to the third nozzle. The nozzles 249a to 249c are made of heat-resistant materials such as quartz or SiC. Gas supply pipes 232a to 232c are connected to each of the nozzles 249a to 249c. Each of the nozzles 249a to 249c is a separate nozzle, and nozzles 249b and 249c are respectively installed adjacent to nozzle 249a.

[0033] On gas supply pipes 232a to 232c, mass flow controllers (MFCs) 241a to 241c (flow controllers) and valves 243a to 243c (on / off valves) are sequentially installed from the upstream side of the gas flow. Gas supply pipes 232d and 232g are connected to gas supply pipe 232a downstream of valve 243a. Gas supply pipes 232e and 232h are connected to gas supply pipe 232b downstream of valve 243b. Gas supply pipes 232f and 232i are connected to gas supply pipe 232c downstream of valve 243c. On gas supply pipes 232d to 232i, MFCs 241d to 241i and valves 243d to 243i are sequentially installed from the upstream side of the gas flow. Gas supply pipes 232a to 232i are made of a metal material such as SUS.

[0034] like Figure 2As shown, nozzles 249a to 249c are respectively arranged vertically above the inner wall of the reaction tube 203 and the wafer 200 in a ring-shaped space when viewed from above. That is, nozzles 249a to 249c are respectively arranged along the wafer arrangement area horizontally surrounding the wafer arrangement area on the side of the wafer arrangement area where the wafers 200 are arranged. When viewed from above, nozzle 249b is arranged to clamp the center of the wafer 200 that has been moved into the processing chamber 201, and is aligned with the exhaust port 231a (described later) in a straight line. Nozzles 249b and 249c are arranged to clamp the straight line L passing through the center of nozzle 249a and exhaust port 231a from both sides along the inner wall of the reaction tube 203 (outer periphery of the wafer 200). Straight line L is also a straight line passing through the center of nozzle 249a and wafer 200. That is, nozzle 249c can also be positioned on the opposite side of nozzle 249b, sandwiching the straight line L. Nozzles 249b and 249c are arranged linearly symmetrically about the straight line L. Gas supply holes 250a to 250c are respectively provided on the side of nozzles 249a to 249c. Gas supply holes 250a to 250c are opened so that they face exhaust port 231a when viewed from above, allowing gas to be supplied toward wafer 200. Multiple gas supply holes 250a to 250c are provided from the lower part to the upper part of reaction tube 203.

[0035] A raw material gas containing the main element (specified element) constituting the film formed on the wafer 200 is supplied into the processing chamber 201 from the gas supply pipe 232a through MFC 241a, valve 243a, and nozzle 249a.

[0036] Seed gas is supplied to the processing chamber 201 from the gas supply pipe 232b through MFC 241b, valve 243b, and nozzle 249b.

[0037] Dopant gas containing dopants (impurities) added to the film formed on the wafer 200 is supplied into the processing chamber 201 from the gas supply pipe 232c via MFC241c, valve 243c, and nozzle 249c.

[0038] Reducing gas is supplied to the processing chamber 201 from the gas supply pipe 232d, through MFC 241d, valve 243d, gas supply pipe 232a, and nozzle 249a.

[0039] Etching agent is supplied to the processing chamber 201 from the gas supply pipe 232e through MFC 241e, valve 243e, gas supply pipe 232b, and nozzle 249b.

[0040] Modified gas is supplied to the processing chamber 201 from the gas supply pipe 232f through MFC 241f, valve 243f, gas supply pipe 232c, and nozzle 249c.

[0041] Inactive gases are supplied to the treatment chamber 201 from gas supply pipes 232g to 232i via MFCs 241g to 241i, valves 243g to 243i, gas supply pipes 232a to 232c, and nozzles 249a to 249c, respectively. These inactive gases function as purge gases, carrier gases, and dilution gases.

[0042] The raw material gas supply system mainly consists of gas supply pipe 232a, MFC241a, and valve 243a. The seed gas supply system mainly consists of gas supply pipe 232b, MFC241b, and valve 243b. The dopant gas supply system mainly consists of gas supply pipe 232c, MFC241c, and valve 243c. The reducing gas supply system mainly consists of gas supply pipe 232d, MFC241d, and valve 243d. The etchant supply system (etchant exposure system) mainly consists of gas supply pipe 232e, MFC241e, and valve 243e. The modification gas supply system mainly consists of gas supply pipes 232g-232i, MFC241g-241i, and valves 243g-243i. The inactive gas supply system mainly consists of gas supply pipes 232g-232i, MFC241g-241i, and valves 243g-243i.

[0043] It should be noted that at least any one of the raw material gas, seed gas, dopant gas, reducing gas, and modifying gas is also referred to as processing gas (first processing gas, second processing gas), and at least any one of the raw material gas supply system, seed gas supply system, and dopant gas supply system is also referred to as processing gas supply system (first processing gas supply system, second processing gas supply system).

[0044] Any or all of the aforementioned gas supply systems can also be configured as an integrated gas supply system 248, which integrates valves 243a-243i, MFCs 241a-241i, etc. The integrated gas supply system 248 is configured to connect to each of the gas supply pipes 232a-232i, and to control the supply of various gases to the gas supply pipes 232a-232i, i.e., the opening and closing of valves 243a-243i, and the flow regulation of MFCs 241a-241i, etc., using the controller 121 described later. The integrated gas supply system 248 can be configured as an integral or separate integrated unit, allowing for assembly and disassembly relative to the gas supply pipes 232a-232i, and enabling maintenance, replacement, and addition of the integrated gas supply system 248 at the integrated unit level.

[0045] An exhaust port 231a is provided on the lower side wall of the reaction tube 203 to exhaust the atmosphere inside the processing chamber 201. For example... Figure 2 As shown, the exhaust port 231a, viewed from above, is positioned opposite (facing) the nozzles 249a-249c (gas supply holes 250a-250c) while the wafer 200 is clamped. The exhaust port 231a may also be positioned from the lower part of the sidewall of the reaction tube 203 along the upper part, i.e., along the wafer arrangement area. An exhaust pipe 231 is connected to the exhaust port 231a. The exhaust pipe 231 is made of a metal material such as SUS. A vacuum pump 246, serving as a vacuum exhaust device, is connected to the exhaust pipe 231 via a pressure sensor 245 (which detects the pressure inside the processing chamber 201) and an APC (Auto Pressure Controller) valve 244 (which acts as a pressure regulator). The APC valve 244 is configured such that by opening and closing the valve while the vacuum pump 246 is operating, vacuum exhaust and vacuum exhaust can be stopped within the processing chamber 201. Furthermore, by adjusting the valve opening based on pressure information detected by the pressure sensor 245 while the vacuum pump 246 is operating, the pressure within the processing chamber 201 can be regulated. The exhaust system mainly consists of the exhaust pipe 231, the APC valve 244, and the pressure sensor 245. It is also possible to include the vacuum pump 246 within the exhaust system.

[0046] Below the manifold 209, a sealing cover 219, serving as a furnace opening cover, is provided to airtightly seal the lower opening of the manifold 209. The sealing cover 219 is made of a metal material such as SUS and is formed in a disc shape. An O-ring 220b, serving as a sealing member, is provided on the upper surface of the sealing cover 219 and abuts against the lower end of the manifold 209. Below the sealing cover 219, a rotation mechanism 267 is provided to rotate the crystal boat 217 (described later). The rotation shaft 255 of the rotation mechanism 267, made of a metal material such as SUS, passes through the sealing cover 219 and is connected to the crystal boat 217. The rotation mechanism 267 is configured to rotate the wafer 200 by rotating the crystal boat 217. The sealing cover 219 is configured to be raised and lowered vertically using a crystal boat lift 115, which is a lifting mechanism located outside the reaction tube 203. The crystal boat lift 115 is configured as a conveying device (conveying mechanism) that moves the wafer 200 into the processing chamber 201 and out of the processing chamber 201 by raising and lowering the sealing cover 219.

[0047] Below the manifold 209, a gate 219s, serving as a furnace opening cover, is provided. This gate can airtightly seal the lower opening of the manifold 209 while the sealing cover 219 is lowered and the crystal boat 217 is removed from the processing chamber 201. The gate 219s is made of a metal material such as SUS and is formed in a disc shape. An O-ring 220c, serving as a sealing component, is provided on the upper surface of the gate 219s, abutting against the lower end of the manifold 209. The opening and closing actions (lifting, rotating, etc.) of the gate 219s are controlled by a gate opening and closing mechanism 115s.

[0048] The crystal boat 217, serving as a substrate support, is configured such that multiple wafers (e.g., 25 to 200 wafers) 200 are arranged horizontally and centered relative to each other in a vertical direction, and the wafers 200 are supported in multiple layers, i.e., the multiple wafers 200 are arranged at intervals. The crystal boat 217 is made of a heat-resistant material such as quartz or SiC. At the bottom of the crystal boat 217, a heat-insulating plate 218 made of a heat-resistant material such as quartz or SiC is supported in multiple layers.

[0049] A temperature sensor 263, serving as a temperature detector, is installed inside the reaction tube 203. By adjusting the energization of the heater 207 based on the temperature information detected by the temperature sensor 263, the temperature within the processing chamber 201 is adjusted to achieve the desired temperature distribution. The temperature sensor 263 is disposed along the inner wall of the reaction tube 203.

[0050] like Figure 3 As shown, the controller 121, serving as the control unit (control means), is configured as a computer equipped with a CPU (Central Processing Unit) 121a, RAM (Random Access Memory) 121b, a storage device 121c, and an I / O port 121d. The RAM 121b, storage device 121c, and I / O port 121d are configured to exchange data with the CPU 121a via an internal bus 121e. An input / output device 122, such as a touch panel, is connected to the controller 121. Additionally, an external storage device 123 can be connected to the controller 121.

[0051] The storage device 121c is composed of, for example, flash memory, HDD (Hard Disk Drive), SSD (Solid State Drive), etc. Within the storage device 121c, a control program that controls the operation of the substrate processing apparatus, and a process flow describing the steps and conditions of the substrate processing described later are stored in a readable manner. The process flow is a combination of steps in the substrate processing described later, which enables the controller 121 to execute and obtain a predetermined result, and functions as a program. Hereinafter, the process flow, control program, etc., will be collectively referred to as a program. Furthermore, the process flow will be referred to simply as a process. When the term "program" is used in this specification, there may be cases where only the process flow is included, cases where only the control program is included, or cases where both are included. RAM 121b is configured as a storage area (working area) that temporarily holds programs, data, etc., read by the CPU 121a.

[0052] I / O port 121d is connected to the aforementioned MFC241a~241i, valves 243a~243i, pressure sensor 245, APC valve 244, vacuum pump 246, temperature sensor 263, heater 207, rotating mechanism 267, crystal boat elevator 115, gate opening and closing mechanism 115s, etc.

[0053] CPU 121a is configured to read and execute control programs from storage device 121c, and to read processes from storage device 121c based on input commands from input / output device 122. CPU 121a is configured to control, according to the read processes, various gas flow regulation operations performed using MFCs 241a to 241i, opening and closing operations of valves 243a to 243i, opening and closing operations of APC valve 244, pressure regulation operations performed using APC valve 244 based on pressure sensor 245, starting and stopping vacuum pump 246, temperature regulation operations of heater 207 based on temperature sensor 263, rotation and rotation speed regulation operations of crystal boat 217 performed using rotation mechanism 267, lifting and lowering operations of crystal boat 217 performed using crystal boat elevator 115, and opening and closing operations of gate 219s performed using gate opening and closing mechanism 115s.

[0054] The controller 121 can be configured by installing the aforementioned program stored in the external storage device 123 into a computer. The external storage device 123 includes, for example, a hard disk such as an HDD, an optical disk such as a CD, an optical disk such as an MO, a USB storage device, and a semiconductor storage device such as an SSD. The storage device 121c and the external storage device 123 constitute a computer-readable recording medium. Hereinafter, they will also be collectively referred to as recording media. When the term "recording medium" is used in this specification, there may be a case where only the storage device 121c is included, a case where only the external storage device 123 is included, or a case where both are included. It should be noted that the program can also be provided to the computer without using the external storage device 123, but using communication means such as the Internet or a dedicated line.

[0055] The intermittent substrate processing apparatus described above can be used to construct the substrate processing system in this embodiment.

[0056] (2) Substrate processing process

[0057] Main use Figure 4 (a)~ Figure 4 (g) will be described with reference to an example of a processing sequence for forming a film on a wafer 200, which serves as a substrate, using the aforementioned substrate processing apparatus (as a step in the manufacturing process of a semiconductor device). In the following description, the operation of each part constituting the substrate processing apparatus can be controlled by the controller 121.

[0058] The processing sequence in Method 1 includes the following steps:

[0059] (a) Step A: A first amorphous film is formed on wafer 200 by supplying a first processing gas to wafer 200;

[0060] (b) Step B, by supplying a second processing gas to the wafer 200, a second amorphous film with a crystallization temperature lower than that of the first film is formed on the first film;

[0061] (c) Step C, crystallizing the first and second films formed on wafer 200 by heating; and

[0062] (d) Step D: After crystallizing the first and second films, at least the second film is removed by exposing the surface of the wafer 200 to an etchant.

[0063] In this case, the first film can be made into an undoped film, and the second film can be made into a doped film. The dopant can be at least one of phosphorus (P), boron (B), and arsenic (As).

[0064] In step A, a seed layer is preferably formed before the formation of the first film. At this time, a seed layer is formed on the surface of the wafer 200, and the first film is formed on the seed layer.

[0065] In step A, if a first silicon film without dopant is formed as the first film, a raw material gas such as a silane-based gas can be used as the first processing gas.

[0066] In step B, when forming a second silicon film doped with a dopant as the second film, a raw material gas such as a silane-based gas and a dopant gas can be used as the second processing gas.

[0067] In step C, if a portion of the dopant in the second film diffuses into the first film, in step D, it is preferable to also remove the portion of the dopant in the second film that has diffused into the first film. At this time, in step D, it is preferable to expose the dopant-free surface of the first film.

[0068] The processing sequence in the first method preferably further includes: (e) step E, after step C and before step D, modifying the portion of the first and second films containing dopants. In this case, it is preferable to oxidize the portion of the first and second films containing dopants in step E. This makes it easier to remove the portion of the first and second films containing dopants after step C in step D (easier to etch with an etchant).

[0069] For convenience, the above processing sequence is sometimes shown in this specification as follows. The same wording is also used in the following descriptions of other methods, variations, etc.

[0070] Seed layer formation → First film formation → Second film formation → Crystallization → Modification → Etching

[0071] When the term "wafer" is used in this specification, it may refer to the wafer itself or a laminate of the wafer and a specified layer or film formed on its surface. When the term "surface of the wafer" is used in this specification, it may refer to the surface of the wafer itself or the surface of a specified layer, etc., formed on the wafer. When the phrase "forming a specified layer on the wafer" is used in this specification, it may mean that the specified layer is formed directly on the surface of the wafer itself or that the specified layer is formed on top of a layer, etc., formed on the wafer. The term "substrate" used in this specification has the same meaning as the term "wafer."

[0072] (Wafer filling and crystal boat loading)

[0073] After multiple wafers 200 are loaded onto the wafer boat 217 (wafer filling), the gate 219s is moved by the gate opening and closing mechanism 115s, thereby opening the lower end opening of the manifold 209 (gate opening). Then, as... Figure 1 As shown, a crystal boat 217 supporting multiple wafers 200 is lifted by a crystal boat elevator 115 and moved into the processing chamber 201 (crystal boat loading). In this state, the sealing cap 219 is in a state where the lower end of the manifold 209 is sealed by means of an O-ring 220b. It should be noted that, as Figure 4 As shown in (a), a silicon oxide film (SiO film) is pre-formed on the surface of wafer 200 as an oxide film.

[0074] (Pressure and temperature regulation)

[0075] After the crystal boat is loaded, vacuum pump 246 is used to perform vacuum venting (pressure reduction venting) to bring the processing chamber 201 (i.e., the space where the wafer 200 exists) to the desired pressure (vacuum level). At this time, pressure sensor 245 measures the pressure in the processing chamber 201, and APC valve 244 is controlled based on the measured pressure information (pressure regulation). Additionally, the wafer 200 in the processing chamber 201 is heated by heater 207 to achieve the desired processing temperature. At this time, the energization of heater 207 is controlled based on temperature information detected by temperature sensor 263 to achieve the desired temperature distribution in the processing chamber 201 (temperature regulation). Furthermore, the wafer 200 is rotated using rotation mechanism 267. Venting in the processing chamber 201, heating of the wafer 200, and rotation are all performed continuously, at least until the processing of the wafer 200 is completed.

[0076] (Step A)

[0077] Then, proceed to step A. In this step, the seed layer formation and the first film formation are performed sequentially.

[0078] [Seed layer formation]

[0079] During the formation of the seed layer, the following steps 1 and 2 are performed sequentially.

[0080] [Step 1]

[0081] In this step, seed gas is supplied to the surface of the oxide film formed on the wafer 200 within the processing chamber 201.

[0082] Specifically, valve 243b is opened, allowing seed gas to flow into gas supply pipe 232b. The seed gas flow rate is regulated using MFC 241b, and it is supplied to processing chamber 201 through nozzle 249b and exhausted from exhaust pipe 231. At this time, seed gas is supplied to wafer 200 (seed gas supply). Alternatively, valves 243g to 243i can be opened to supply inactive gases to processing chamber 201 through nozzles 249a to 249c respectively.

[0083] Examples of processing conditions for seed gas supply can be given as follows:

[0084] Seed gas supply flow rate: 0.1–1 slm;

[0085] Seed gas supply time: 0.5–2 minutes;

[0086] Inactive gas supply flow rate (per gas supply tube): 0–20 slm;

[0087] Processing temperature: 350~450℃, preferably 350~400℃;

[0088] Processing pressure: 277~1200Pa, preferably 667~1200Pa.

[0089] It should be noted that the numerical ranges expressed in this specification, such as "277~1200Pa," refer to the inclusion of both the lower and upper limits within that range. Therefore, for example, "277~1200Pa" means "above 277Pa and below 1200Pa." The same applies to other numerical ranges. Furthermore, "processing temperature" in this specification refers to the temperature of the wafer 200 or the temperature within the processing chamber 201, and "processing pressure" refers to the pressure within the processing chamber 201, which serves as the space where the wafer 200 is located. Additionally, "gas supply flow rate: 0 slm" indicates the condition where the gas is not supplied. These same principles apply in the following descriptions.

[0090] For example, using a chlorosilane-based gas as a seed gas, by supplying the seed gas to the wafer 200 under the above-described processing conditions, silicon (Si) contained in the seed gas is adsorbed onto the surface of the wafer 200, thereby forming a seed crystal (nucleus). Under the above-described processing conditions, the nucleus formed on the surface of the wafer 200 contains a predetermined amount of chlorine (Cl). Furthermore, under the above-described processing conditions, the crystalline structure of the nucleus formed on the surface of the wafer 200 becomes amorphous (amorphous material).

[0091] After a nucleus is formed on the surface of the wafer 200, valve 243b is closed, and the supply of seed gas to the processing chamber 201 is stopped. Then, the vacuum in the processing chamber 201 is purged to remove any remaining gases (purge) from the processing chamber 201. At this time, valves 243g to 243i are opened to supply inactive gases to the processing chamber 201.

[0092] For example, monochlorosilane (SiH3Cl, abbreviated as MCS), dichlorosilane (SiH2Cl2, abbreviated as DCS), trichlorosilane (SiHCl3, abbreviated as TCS), tetrachlorosilane (SiCl4, abbreviated as STC), hexachlorodisilane (Si2Cl6, abbreviated as HCDS), octachlorotrisilane (Si3Cl8, abbreviated as OCTS), and other chlorosilane-based gases can be used as seed gases. More than one of the gases illustrated herein can be used as seed gases.

[0093] For example, fluorosilane gases such as tetrafluorosilane (SiF4) gas and difluorosilane (SiH2F2) gas, bromosilane gases such as tetrabromosilane (SiBr4) gas and dibromosilane (SiH2Br2) gas, and iodosilane gases such as tetraiodosilane (SiI4) gas and diiodosilane (SiH2I2) gas can be used as seed gases. More than one of the various gases illustrated herein can be used as seed gases.

[0094] As inert gases, for example, rare gases such as nitrogen (N2), argon (Ar), helium (He), neon (Ne), and xenon (Xe) can be used. More than one of the gases illustrated here can be used as an inert gas. This also applies to the steps described later.

[0095] [Step 2]

[0096] Then, reducing gas is supplied to the wafer 200 in the processing chamber 201, that is, to the nucleus formed on the surface of the oxide film.

[0097] Specifically, valve 243d is opened, allowing reducing gas to flow into gas supply pipe 232d. The reducing gas flow rate is regulated using MFC 241d, and it is supplied to processing chamber 201 through gas supply pipe 232a and nozzle 249a, and exhausted from exhaust port 231a. At this time, reducing gas is supplied to wafer 200 (reducing gas supply). Alternatively, valves 243g to 243i can be opened to supply inactive gas into processing chamber 201 through nozzles 249a to 249c.

[0098] As an example of the processing conditions in the supply of reducing gas, the reducing gas supply flow rate can be 2 to 10 slm.

[0099] Reducing gas supply time: 2-5 minutes;

[0100] Inactive gas supply flow rate (per gas supply tube): 0–20 slm;

[0101] Processing pressure: 1333~13332Pa.

[0102] Other processing conditions can be set to be the same as those when the seed gas is supplied.

[0103] By supplying a reducing gas to the wafer 200 under the aforementioned processing conditions, Cl can be detached from the nuclei formed on the surface of the wafer 200. The Cl detached from the nuclei generates a gaseous substance containing Cl, which is then discharged from the processing chamber 201. It should be noted that, in this method, the pressure (processing pressure) of the space containing the wafer 200 when the reducing gas is supplied is higher than the pressure (processing pressure) of the space containing the wafer 200 when the seed gas is supplied. By operating in this way, the detachment of Cl from the nuclei can be promoted when the reducing gas is supplied. As a result, the seed layer formed on the wafer 200 can be a layer with a lower Cl concentration.

[0104] After Cl detaches from the nucleus formed on the surface of wafer 200, valve 243d is closed to stop the supply of reducing gas to the processing chamber 201. Then, using the same processing steps and conditions as the purging in step 1, the gas and other gases remaining in the processing chamber 201 are removed from the processing chamber 201.

[0105] As a reducing gas, hydrogen (H2), deuterium (D2), monosilane (SiH4), and other hydrogen (H)-containing gases can be used. D2 gas can also be described as... 2 H2 gas. As a reducing gas, one or more of the various gases shown in this example can be used.

[0106] [Performed a specified number of times]

[0107] By alternating steps 1 and 2 above, i.e., performing them asynchronously and non-simultaneously, a predetermined number of times (n times, where n is one or more integers), such as... Figure 4 As shown in (b), a seed layer, i.e., a silicon seed layer, formed by high-density formation of the aforementioned nuclei can be formed on the wafer 200, i.e., on the oxide film formed on the surface of the wafer 200. In this method, by alternately performing steps 1 and 2, i.e., by supplying a reducing gas whenever a seed gas is supplied, causing Cl to detach from the nuclei formed on the surface of the wafer 200, the seed layer formed on the wafer 200 can be made into a layer with a low Cl concentration. Under the above processing conditions, the crystalline structure of the seed layer formed on the wafer 200 can be made amorphous.

[0108] After the formation of an amorphous seed layer on the wafer 200 is completed, the output of the heater 207 is adjusted to change the temperature inside the processing chamber 201 (i.e., the temperature of the wafer 200) to a temperature higher than the temperature of the wafer 200 during the formation of the seed layer. During the period until the temperature of the wafer 200 reaches the desired temperature and stabilizes, valves 243g to 243i are opened, and inactive gases are supplied into the processing chamber 201 through nozzles 249a to 249c, respectively. The gases are then exhausted through exhaust port 231a, and the processing chamber 201 is purged.

[0109] [First membrane formation]

[0110] After the seed layer is formed, the first film is formed. In this step, a raw material gas, which serves as the first processing gas, is supplied to the surface of the wafer 200, i.e., the amorphous seed layer formed on the wafer 200, within the processing chamber 201.

[0111] Specifically, valve 243a is opened, allowing raw material gas to flow into the gas supply pipe 232a. The flow rate of the raw material gas is regulated using MFC 241a, and it is supplied to the processing chamber 201 through nozzle 249a and exhausted from the exhaust port 231a. At this time, raw material gas is supplied to the wafer 200 (raw material gas supply). Alternatively, valves 243g to 243i can be opened to supply inactive gas into the processing chamber 201 through nozzles 249a to 249c respectively.

[0112] Examples of processing conditions during the formation of the first membrane include:

[0113] Raw material gas supply flow rate: 0.01~5slm;

[0114] Raw material gas supply time: 1–300 minutes;

[0115] Inactive gas supply flow rate (per gas supply tube): 0–20 slm;

[0116] Processing temperature: 450~550℃; Processing pressure: 30~400Pa.

[0117] Using a silane-based gas as the feed gas, the feed gas is supplied to the wafer 200 under the above processing conditions. This allows the feed gas to decompose in the gas phase, causing Si to adsorb (accumulate) on the surface of the wafer 200, i.e., on the seed layer formed on the wafer 200. Thus, as... Figure 4As shown in (c), a first silicon film can be formed on the seed layer formed on the wafer 200. When a silane-based gas without Cl is used as the raw material gas, the first film formed on the wafer 200 becomes a Cl-free film. Furthermore, under the above processing conditions, the crystal structure of the first film formed on the wafer 200 becomes amorphous. Additionally, the crystal structure of the seed layer formed on the wafer 200 also remains amorphous.

[0118] After the formation of the first amorphous film on the wafer 200 is completed, valve 243a is closed and the supply of raw material gas to the processing chamber 201 is stopped. Then, using the same processing steps and conditions as the purging during the formation of the seed layer, the gas and other gases remaining in the processing chamber 201 are removed from the processing chamber 201.

[0119] As feedstock gases, for example, monosilane (SiH4 gas), disilane (Si2H6 gas), trisilane (Si3H8 gas), and tetrasilane (Si4H6 gas) can be used. 10 ) gas, pentasilane (Si5H 12 ) gas, hexasilane (Si6H) 14 The raw material gas may be a silicon hydride gas such as a silane gas. One or more of the various gases illustrated herein may be used as the raw material gas. It should be noted that, in order to reliably ensure that the first film at the end of its formation is amorphous, a low-grade silicon hydride gas such as a monosilane gas is preferably used as the raw material gas.

[0120] (Step B)

[0121] After step A is completed, step B is performed to form the second film. In this step, raw material gas and dopant gas are supplied to the surface of the wafer 200, i.e., the first film formed on the wafer 200, in the processing chamber 201 as the second processing gas.

[0122] Specifically, valves 243a and 243c are opened, allowing raw material gas and dopant gas to flow into gas supply pipes 232a and 232c, respectively. The flow rates of the raw material gas and dopant gas are regulated by MFCs 241a and 241c, respectively, and supplied to the processing chamber 201 through nozzles 249a and 249c, and exhausted from the exhaust port 231a. At this time, raw material gas and dopant gas (raw material gas + dopant gas supply) are supplied to the wafer 200. Alternatively, valves 243g to 243i can be opened at this time, supplying inactive gas into the processing chamber 201 through nozzles 249a to 249c.

[0123] Examples of processing conditions for the formation of the second membrane include:

[0124] Raw material gas supply flow rate: 0.01~5slm;

[0125] Dopant gas supply flow rate: 0.01–5 slm;

[0126] Gas supply time: 1–300 minutes;

[0127] Processing temperature: 450~550℃;

[0128] Processing pressure: 30-400 Pa.

[0129] Other processing conditions can be set to be the same as those used when the first membrane was formed.

[0130] Using silane-based gas as the raw material gas and phosphorus (P)-containing gas as the dopant gas, these gases are supplied to wafer 200 under the above processing conditions, causing the raw material gas and dopant gas to decompose separately in the gas phase. This allows Si to be adsorbed (deposited) on the surface of wafer 200, i.e., on the amorphous first film formed on wafer 200. Thus, as... Figure 4 As shown in (d), a second silicon film doped with P as a dopant can be formed on the wafer 200, that is, on the first film formed on the wafer 200, to serve as the second film. When a silane-based gas without Cl is used as the raw gas, the second film formed on the wafer 200 becomes a Cl-free film. Furthermore, under the above processing conditions, the crystal structure of the second film formed on the wafer 200 becomes amorphous. In addition, the crystal structure of the seed layer and the first film formed on the wafer 200 also remain amorphous.

[0131] After the formation of the second amorphous film on the wafer 200 is completed, valves 243a and 243c are closed to stop the supply of raw material gas and dopant gas to the processing chamber 201. Then, using the same processing steps and conditions as the purging during the formation of the seed layer, the gas and other gases remaining in the processing chamber 201 are removed from the processing chamber 201.

[0132] As the feed gas, one or more of the various silicon hydride gases exemplified in the first film formation can be used. It should be noted that, in order to reliably produce an amorphous state of the second film at the end of the second film formation, a low-grade silicon hydride gas such as monosilane gas is preferably used as the feed gas.

[0133] As dopant gases, phosphorus (P) gases such as phosphine (PH3) gas, boron (B) gases such as diborane (B2H6) gas, and arsenic (As) gases such as arsine (AsH3) gas can be used. One or more of these can be used as dopant gases.

[0134] (Step C)

[0135] After step B is completed, crystallization is carried out as step C.

[0136] Specifically, the output of heater 207 is adjusted to change the temperature inside processing chamber 201, i.e., the temperature of wafer 200, to a temperature higher than the temperature of wafer 200 during the formation of the second film, so that the seed layer, the first film, and the second film are subjected to heat treatment (annealing) respectively. At this time, valves 243g to 243i can also be opened to supply inactive gas into processing chamber 201 through nozzles 249a to 249c respectively.

[0137] Examples of treatment conditions during crystallization include:

[0138] Inactive gas supply flow rate (each gas supply pipe): 0~20slm;

[0139] Processing time: 60–600 minutes;

[0140] Processing temperature: 550~650℃;

[0141] Processing pressure: 1~101325Pa.

[0142] Annealing is performed under the above conditions, such as Figure 4 As shown in (e), the seed layer, the first film, and the second film can each undergo polycrystalline formation (crystallization, i.e., polycrystalline formation). As described above, the first film is an amorphous film without dopant, and the second film is an amorphous film doped with dopant. Therefore, in this step, the crystallization of the second film can begin before the crystallization of the first film. Furthermore, in this step, the crystallization of the second film can end before the crystallization of the first film. Thus, in this step, the first film can be crystallized starting from the grains of the second film. That is, the crystalline state of the second film can be inherited by the first film.

[0143] Furthermore, compared to an undoped amorphous film, a doped amorphous film can increase its grain size during crystallization. In this step, the crystallization of the second film can begin before the crystallization of the first film and end before the crystallization of the first film. As a result, the grain size of the second film, which is formed first, increases, and this increased grain size can be inherited by the first film, which is formed subsequently. Consequently, the grain size of the first film can be increased during crystallization.

[0144] As described above, since the first film inherits the crystalline state of the second film, it is effective to further increase the grain size of the second film in order to increase the grain size of the first film. Here, by making the thickness of the amorphous second film greater than or equal to the thickness of the amorphous first film, the grain size of the crystallized second film can be further increased, and as a result, the grain size of the first film can be further increased. Furthermore, by making the thickness of the amorphous second film thicker than the thickness of the amorphous first film, the grain size of the crystallized second film can be further increased, and as a result, the grain size of the first film can be further increased.

[0145] It should be noted that during annealing under the above-described processing conditions, sometimes a portion of the dopant in the second film diffuses into the first film. Consequently, the first film, for example, in the region near the interface with the second film, may sometimes be in a state where the dopant has been added at a predetermined concentration.

[0146] (Step E)

[0147] After step C is completed, modification is performed as step E. In this step, a modifying gas is supplied to the surface of the wafer 200, i.e., the crystallized second film, inside the processing chamber 201.

[0148] Specifically, valve 243f is opened, allowing modified gas to flow into gas supply pipe 232f. The modified gas flow rate is regulated using MFC 241f, and it is supplied to processing chamber 201 through gas supply pipe 232c and nozzle 249c, and exhausted from exhaust port 231a. At this time, modified gas is supplied to wafer 200 (modified gas supply). Alternatively, valves 243g to 243i can be opened to supply inactive gas into processing chamber 201 through nozzles 249a to 249c respectively.

[0149] As a processing condition during modification, an example can be given:

[0150] Modified gas supply flow rate: 1–10 slm;

[0151] Modified gas supply time: 1–5 minutes;

[0152] Inactive gas supply flow rate (per gas supply tube): 0–20 slm;

[0153] Processing temperature: 500~800℃;

[0154] Processing pressure: 1~101325Pa.

[0155] For example, by using an oxygen-containing gas (oxidizing gas) as the modifying gas and supplying the modifying gas to the wafer 200 under the above processing conditions, the dopants present in the first and second films can be partially oxidized. Thus, as... Figure 4As shown in (f), the portion of the dopant present in the first and second films can be modified into an oxide film that is easy to etch in the etching described later (in the case of forming silicon films as the first and second films, it is a silicon oxide film).

[0156] After the modification of the portion of the dopant present in the first and second films is completed, valve 243f is closed to stop the supply of modified gas to the processing chamber 201. Then, using the same processing steps and conditions as during the purging process for seed layer formation, the gas and other gases remaining in the processing chamber 201 are removed from the processing chamber 201.

[0157] As modifying gases, oxygen (O2), ozone (O3), water vapor (H2O), hydrogen peroxide (H2O2), nitric oxide (NO), nitrous oxide (N2O), nitrogen dioxide (NO2), carbon monoxide (CO), and carbon dioxide (CO2) can be used. In addition to these, gases containing both oxygen and hydrogen (H) can also be used as modifying gases. As for H-containing gases, besides H2, other gases can also be used. 2 H2 gas. For example, O2 gas + H2 gas, O3 gas + H2 gas, etc., can be used as the modifying gas. In addition, a gas that has excited at least any of these into a plasma state can also be used as the modifying gas. More than one of the various gases illustrated herein can be used as the modifying gas.

[0158] It should be noted that when two gases, "containing O gas + containing H gas," are described together in this specification, it refers to a mixture of O gas and H gas. When supplying the mixed gas, the two gases can be mixed (premixed) in the supply pipe and then supplied to the processing chamber 201, or the two gases can be supplied to the processing chamber 201 separately using different supply pipes and mixed in the processing chamber 201 (postmixed).

[0159] (Step D)

[0160] After step E is completed, etching is performed as step D. In this step, the surface of the wafer 200 in the processing chamber 201, that is, the surface of the oxide film modified from the portion of the first and second films in which the dopants are present, is exposed to the etchant.

[0161] Specifically, valve 243e is opened, allowing etchant to flow into gas supply pipe 232e. The etchant flow rate is regulated using MFC 241e, and it is supplied to processing chamber 201 through gas supply pipe 232b and nozzle 249b, and exhausted from exhaust port 231a. At this time, the surface of wafer 200 is exposed to the etchant (etchant exposure). Alternatively, valves 243g to 243i can be opened to supply inactive gases into processing chamber 201 through nozzles 249a to 249c.

[0162] Examples of processing conditions during etching include:

[0163] Etching agent supply flow rate: 1~10 slm;

[0164] Etching agent supply time: 1-10 minutes;

[0165] Inactive gas supply flow rate (per gas supply tube): 0–20 slm;

[0166] Processing temperature: room temperature (25℃) to 1000℃;

[0167] Processing pressure: 133~50000Pa.

[0168] By supplying an etchant to the wafer 200 under the above processing conditions, the portion of the first and second films that has been modified into an oxide film, i.e., the portion where the dopant is present, can be etched (removed). Thus, as... Figure 4 As shown in (g), the dopant-free surface of the first film can be exposed. The first film obtained after etching becomes an undoped film.

[0169] It should be noted that, as described above, during crystallization, sometimes a portion of the dopant in the second film diffuses into the first film. In this case, during etching, at least the second film is removed, as well as the portion of the dopant in the second film that has diffused into the first film. That is, the thickness of the first film after etching is sometimes thinner than the thickness of the first film immediately after its formation, by an amount at least greater than the depth to which the dopant diffused from the second film into the first film during crystallization. Therefore, in this case, in order to make the thickness of the first film obtained after etching, i.e., the final thickness of the first film, the desired thickness, it is preferable that, during the formation of the first film, the first film is formed to a thickness greater than the thickness of the first film obtained after etching, by an amount greater than the depth to which the dopant diffused from the second film into the first film during crystallization. For example, preferably, in the formation of the first film, the first film is formed with a thickness that is thicker than the thickness of the first film obtained after etching by an amount that allows the dopant to diffuse from the second film into the first film only during crystallization.

[0170] After removing the portion of the first and second films that has been modified into an oxide film, i.e. the portion where the dopant is present, valve 243e is closed to stop the supply of etchant to the processing chamber 201. Then, using the same processing steps and conditions as when purging during seed layer formation, the gases and other substances remaining in the processing chamber 201 are removed from the processing chamber 201.

[0171] As etchants, for example, hydrogen fluoride (HF) gas, chlorine trifluoride (ClF3) gas, chlorine fluoride (ClF) gas, fluorine (F2) gas, nitrogen trifluoride (NF3) gas, nitrosyl fluoride (FNO) gas, hydrogen chloride (HCl) gas, chlorine (Cl2) gas, or mixtures thereof can be used. One or more of the gases illustrated herein can be used as etchants. It should be noted that when modifying the portion containing dopants in the first and second films into an oxide film, fluorine-based gases (fluorine-containing gases) such as HF gas are preferably used as etchants. When using fluorine-based gases such as HF gas, the crystalline silicon film, i.e., the polycrystalline silicon film, can be selectively etched only the amount of oxidized film thickness, while the amount of unoxidized film thickness can remain without etching. That is, when using fluorine-based gases such as HF gas, only the amount of oxidized polycrystalline silicon film thickness can be etched to obtain a polycrystalline silicon film of a specified thickness.

[0172] (Post-purging and atmospheric pressure recovery)

[0173] After etching, inert gases are supplied as purge gases into the processing chamber 201 from nozzles 249a to 249c, and exhausted from the exhaust port 231a. This purges the processing chamber 201, removing residual gases and reaction byproducts (post-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 atmospheric pressure (atmospheric pressure restoration).

[0174] (Crystal boat unloading and chip removal)

[0175] Then, the sealing cover 219 is lowered using the crystal boat lift 115, opening the lower end of the manifold 209. The processed wafer 200, supported on the crystal boat 217, is then moved from the lower end of the manifold 209 to the outside of the reaction tube 203 (crystal boat unloading). After unloading, the gate 219s moves, sealing the lower opening of the manifold 209 via the O-ring 220c (gate closing). After the processed wafer 200 is moved to the outside of the reaction tube 203, it is removed from the crystal boat 217 (wafer removal).

[0176] (3) Effects of this method

[0177] According to this method, one or more of the following effects can be obtained.

[0178] (a) By sequentially performing the formation of a first film, a second film, crystallization, and etching, the grain size of the final first film can be increased, and the density of grain boundaries in the final first film can be reduced. As a result, the electron mobility in the final first film can be increased.

[0179] (b) By making the first film an undoped amorphous film and the second film a doped amorphous film, the crystallization of the second film can begin before the crystallization of the first film. This allows the grain size of the first-crystallized film (the second film) to increase, inheriting its grain size from the later-crystallized film (the first film). In other words, the grain size of the first film obtained through crystallization can be increased.

[0180] (c) During crystallization, if a portion of the dopant in the second film diffuses into the first film, during etching, the portion of the dopant diffused from the second film into the first film is also removed, thereby leaving undoped portions in the first film. This exposes the undoped portions in the first film, i.e., the dopant-free portions of the first film. As a result, the first film obtained after etching is an undoped film.

[0181] (d) By modifying the material after crystallization and before etching, the portion of the dopant present in the crystallized first and second films can be easily removed during etching (easily etched by the etchant). Thus, during etching, the portion of the dopant present in the first and second films can be selectively etched.

[0182] (e) During crystallization, by setting the temperature of wafer 200 to above 550°C and below 650°C, the second film can be properly crystallized before the first film, thereby suppressing the diffusion of a portion of the dopant in the second film into the first film.

[0183] (f) When the first film is formed, the first film is formed with a thickness greater than the thickness of the first film obtained after etching by an amount greater than the depth by which the dopant diffuses from the second film into the first film during crystallization, for example, by an amount greater than only that depth, thereby preventing the thickness of the first film obtained after etching from becoming thinner than the necessary thickness.

[0184] (g) During the formation of the second film, by making the thickness of the second film greater than or equal to the thickness of the first film, for example, by making it thicker than the thickness of the first film, the grain size of the second film can be made larger during crystallization, and the grain size can be inherited by the first film, thereby further increasing the grain size of the first film.

[0185] (h) This method is particularly effective when an oxide film is formed on the surface of the wafer 200 before film formation. When a film is formed on an oxide film, the grain size of that film can sometimes become smaller, but according to this method, even when a film is formed on an oxide film, the grain size of that film can be increased. That is, according to this method, a film that increases the grain size can be formed on an oxide film.

[0186] (i) The above-mentioned effects can also be obtained when using the above-mentioned seed gases, the above-mentioned reducing gases, the above-mentioned raw material gases, the above-mentioned modifying gases, the above-mentioned etchants, and the above-mentioned inactive gases.

[0187] (4) Variations

[0188] It should be noted that the above method describes an example of partially modifying the dopants present in the crystallized first and second films and then removing them by dry etching, but the present invention is not limited thereto.

[0189] For example, the dopants present in the crystallized first and second films can be partially modified and removed by wet etching. In this case, instead of an etching gas, an aqueous HF solution is used as the etchant, and the surface of the wafer 200 is exposed to the HF aqueous solution, thereby performing the same etching as described above. In this case, the same effect as described above can also be obtained.

[0190] Furthermore, for example, in the above-mentioned methods, such as Figure 4 (a)~ Figure 4 As shown in (g), an example is described for etching after partial modification of the dopants present in the crystallized first and second films, but the present invention is not limited thereto.

[0191] For example, the following processing order, Figure 5 (a)~ Figure 5 As shown in (f), etching can be performed without modifying the dopant present in the crystallized first and second films. That is, modification can be omitted. In this case, chlorine-based gases (chlorine-containing gases) such as HCl gas and Cl2 gas are preferably used as etchants.

[0192] Seed layer formation → First film formation → Second film formation → Crystallization → Etching

[0193] In this case, the same effect as described above can be achieved.

[0194] Furthermore, the above description focuses on an example where silicon films are formed on wafer 200 as the first and second films, but this method is not limited to these. For example, this method can also be applied when germanium films (Ge films) or silicon-germanium films (SiGe films) are formed on wafer 200 as the first and second films. In these cases, the same effect as described above can be obtained.

[0195] <Second aspect of the present invention>

[0196] In the first embodiment described above, step B (formation of the second film) illustrates an example of forming a second film with a lower crystallization temperature than the first film, i.e., a second film doped with a dopant, on the first film. However, in step B, an undoped second film may also be formed as the second film.

[0197] The processing sequence in the second method includes the following steps: (a) step A, forming an amorphous first film on the wafer 200 by supplying a first processing gas to the wafer 200; (b) step B, forming an amorphous second film on the first film by supplying a second processing gas to the wafer 200; (c) step C, crystallizing the first and second films formed on the wafer 200 by heating them; and (d) step D, removing at least the second film by exposing the surface of the wafer 200 to an etchant after the first and second films have been crystallized.

[0198] In the second method, both the first and second films are made without dopant.

[0199] In the second method, preferably, similar to the first method, a silicon seed layer is formed as a seed layer in step A before the formation of the first film. At this time, the seed layer will be formed on the surface of the wafer 200, and the first film will be formed on the seed layer.

[0200] In step A, if an undoped first silicon film is formed as the first film, a raw material gas such as a silane-based gas can be used as the first processing gas.

[0201] In step B, if an undoped second silicon film is formed as the second film, a raw material gas such as a silane-based gas can be used as the second processing gas.

[0202] Preferably, the processing sequence in the second method further includes: (e) step E, modifying the second film after step C and before step D. In this case, the second film is preferably oxidized in step E. This allows the second film after step C to be easily removed in step D (easily etched by an etchant).

[0203] The second method differs from the first method only in that the second film formed in step B does not contain dopant (only in step B is no dopant gas supplied); otherwise, it is the same as the first method. The processing steps and conditions in each step of the processing sequence of the second method can be set to be the same as those in each step of the processing sequence of the first method described above.

[0204] In this method, the same effect as in the first method can be achieved.

[0205] It should be noted that, in this method, either dry etching or wet etching can be used to remove the crystallized and modified second film. In either case, the same effect as described above can be obtained.

[0206] Furthermore, in this method, similar to method 1, such as... Figure 6 (a)~ Figure 6 As shown in (g), the crystallized and modified second film can also be etched. Additionally, as... Figure 7 (a)~ Figure 7 As shown in (f), the second film after crystallization can also be etched without modifying it. That is, after crystallization, modification can be performed before etching, or no modification may be performed. In either case, it is preferable to use the same etchant as in the first method. That is, when etching the second film that has been crystallized and modified into an oxide film, fluorine-based gases (fluorine-containing gases) such as HF gas or aqueous HF solutions are preferred as the etchant. In addition, when etching without modifying the second film after crystallization, chlorine-based gases (chlorine-containing gases) such as HCl gas or Cl2 gas are preferred as the etchant. In any case, the same effect as the above method can be obtained.

[0207] <Other aspects of the invention>

[0208] The various embodiments of the present invention have been specifically described above. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from its spirit.

[0209] In the above description, an example of performing a series of steps from seed layer formation to etching within the same processing chamber 201 (in situ) has been given. However, the present invention is not limited to this approach. For example, steps from seed layer formation to a portion of the steps in a series of steps may be performed within the same processing chamber, while subsequent steps may be performed in other processing chambers (non-in situ).

[0210] For example, different independent devices (first substrate processing device, second substrate processing device, and third substrate processing device) can be used to perform seed layer formation, first film formation, second film formation, crystallization, and etching respectively. In this case, such as Figure 8 As shown in (a), a substrate processing system can be constituted by a first substrate processing apparatus, a second substrate processing apparatus, and a third substrate processing apparatus.

[0211] Furthermore, for example, different independent devices (first substrate processing device, second substrate processing device) can be used to perform a series of steps, including seed layer formation, first film formation, second film formation, and crystallization, as well as etching. At this time, such as Figure 8 As shown in (b), a substrate processing system can be formed by a first substrate processing device and a second substrate processing device.

[0212] Furthermore, for example, seed layer formation, first film formation, second film formation, crystallization, and etching can be performed separately in different processing chambers (first processing chamber, second processing chamber, and third processing chamber) within the cluster-type device. In this case, such as Figure 9 As shown, a substrate processing system can be constructed using a cluster-type device having a first processing chamber, a second processing chamber, and a third processing chamber. It should be noted that... Figure 9 The fourth processing chamber can be used as a processing chamber for other processes.

[0213] Furthermore, for example, a series of steps, including seed layer formation, first film formation, second film formation, and crystallization, as well as etching, can be performed separately in different processing chambers (first processing chamber, second processing chamber) within the cluster-type device. At this time, as... Figure 9 As shown, a cluster-type device having a first processing chamber and a second processing chamber can be used to construct a substrate processing system. It should be noted that... Figure 9 The third and fourth processing chambers can be used as processing chambers for other processes. In addition, a series of steps, including the formation of the first film, the formation of the second film, crystallization, and etching, can be performed in the third and fourth processing chambers, respectively.

[0214] In these cases, the same effect as described above can be achieved. It should be noted that in all the above cases, if a series of steps are performed in situ, the wafer 200 is not exposed to the atmosphere during the process, and processing can continue while the wafer 200 is placed in a vacuum, enabling stable substrate processing. Furthermore, if some steps are performed non-situ, the temperature in each processing chamber can be preset to, for example, the processing temperature of each step or a similar temperature, which can shorten the time required for temperature conditioning and improve production efficiency.

[0215] Preferably, the processes used in substrate processing are prepared individually according to the processing requirements and pre-stored in the storage device 121c via electrical communication lines and external storage device 123. Then, when processing begins, preferably, the CPU 121a appropriately selects a suitable process from the multiple processes stored in the storage device 121c according to the substrate processing requirements. This allows for the reproducible formation of films of various types, compositions, qualities, and thicknesses within a single substrate processing apparatus. Furthermore, it reduces operator workload, avoids operational errors, and enables rapid initiation of processing.

[0216] The aforementioned process is not limited to newly manufactured processes. For example, it can also be prepared by modifying an existing process already installed in the substrate processing apparatus. In the case of process modification, the modified process can also be installed in the substrate processing apparatus via an electrical communication line or a recording medium containing the modified process. Alternatively, the existing process already installed in the substrate processing apparatus can be directly modified by operating the input / output device 122 of the existing substrate processing apparatus.

[0217] In the above description, an example of forming a film using a batch substrate processing apparatus that processes multiple substrates at a time has been explained. The present invention is not limited to the above method; for example, it can also be suitably applied to the case of forming a film using a monolithic substrate processing apparatus that processes one or more substrates at a time. Furthermore, in the above description, an example of forming a film using a substrate processing apparatus with a hot-wall type processing furnace has been explained. The present invention is not limited to the above method; it can also be suitably applied to the case of forming a film using a substrate processing apparatus with a cold-wall type processing furnace.

[0218] When using these substrate processing devices, film formation can be performed in the same manner and under the same processing conditions as described above and in the modified examples, and the same effect can be obtained.

[0219] Furthermore, the above methods and variations can be used in appropriate combinations. In this case, the processing steps and conditions can be the same as those in the methods described above.

[0220] Example

[0221] As an example 1, using Figure 1 The substrate processing apparatus shown forms an evaluation sample by forming a silicon film on a wafer on which a silicon oxide film has been formed, using a first-mode processing sequence (seed layer formation, first film formation, second film formation, crystallization, modification, and etching). The processing conditions in each step are set to specified conditions within the range of processing conditions in each step of the first-mode processing sequence. The thickness of the amorphous silicon film (undoped) as the first film is 30 nm, the thickness of the amorphous silicon film (P-doped) as the second film is 15 nm, and etching is performed to finally form a silicon film (undoped) with a thickness of 30 nm on the wafer.

[0222] As a comparative example 1, using Figure 1 The substrate processing apparatus shown forms an evaluation sample by performing seed layer formation, first film formation, and crystallization in the processing sequence of the first method to form a silicon film on a wafer on which a silicon oxide film is formed. The processing conditions in each step are the same as those in each step of Example 1. It should be noted that by performing crystallization, the thickness of the final undoped silicon film formed on the wafer is 30 nm.

[0223] In addition, the grain size of the silicon film in the respective evaluation samples of Example 1 and Comparative Example 1 was measured. The results are shown below. Figure 10 .like Figure 10 As shown, compared with Comparative Example 1, it was confirmed that the grain size of the silicon film could be increased in Example 1.

[0224] As an example 2, using Figure 1 The substrate processing apparatus shown forms a silicon film on a wafer on which a silicon oxide film is formed, using a second processing sequence (seed layer formation, first film formation, second film formation, crystallization, modification, and etching), to produce an evaluation sample. The processing conditions in each step are defined within the range of processing conditions in each step of the second processing sequence. The thickness of the amorphous silicon film (undoped) as the first film is 30 nm, the thickness of the amorphous silicon film (undoped) as the second film is 15 nm, and the thickness of the silicon film (undoped) finally formed on the wafer by etching is 30 nm.

[0225] As a comparative example 2, using Figure 1 The substrate processing apparatus shown forms a silicon film on a wafer with a silicon oxide film on its surface by performing the seed layer formation, first film formation, and crystallization steps in the second processing sequence to produce an evaluation sample. The processing conditions in each step are set to be the same as those in each step of Example 2. It should be noted that the thickness of the final undoped silicon film formed on the wafer by crystallization is 30 nm.

[0226] In addition, the grain size of the silicon film in the evaluation samples of Example 2 and Comparative Example 2 was measured. The results are shown below. Figure 11 .like Figure 11 As shown, compared with Comparative Example 2, it was confirmed that Example 2 can increase the grain size of the silicon film.

[0227] It should be noted that when comparing Example 1 and Example 2, Example 1, compared to Example 2, i.e., the processing order of the first method compared to the processing order of the second method, confirms that the grain size of the silicon film can be increased.

[0228] The above describes various aspects of the present invention, but the present invention also includes the following aspects.

[0229] (Postscript 1)

[0230] According to other aspects of the present invention, a method for manufacturing a semiconductor device or a substrate processing method is provided, comprising the following steps:

[0231] (a) A process of forming an amorphous first film on the substrate by supplying a first processing gas to the substrate;

[0232] (b) A process of forming an amorphous second film on the first film by supplying a second processing gas to the substrate;

[0233] (c) A process of crystallizing the first film and the second film formed on the substrate by heating; and

[0234] (d) The process of removing at least the second film by exposing the surface of the substrate to an etchant after crystallizing the first film and the second film.

[0235] (Postscript 2)

[0236] The method described in Appendix 1 further includes (e) a step of modifying the second membrane described above after (c) and before (d).

[0237] (Note 3)

[0238] The method described in Appendix 1 or 2 further includes (e) the step of oxidizing the second membrane described above after (c) and before (d).

[0239] (Postscript 4)

[0240] According to a further embodiment of the present invention, a substrate processing system is provided, comprising:

[0241] A first processing gas supply system for supplying a first processing gas to a substrate;

[0242] A second processing gas supply system for supplying a second processing gas to a substrate;

[0243] Heater for heating substrates;

[0244] An etchant exposure system that exposes a substrate to an etchant;

[0245] The control unit is configured to control the first processing gas supply system, the second processing gas supply system, the heater, and the etchant exposure system in a manner that allows for the execution of each of the processes (steps) described in Appendix 1.

[0246] (Note 5)

[0247] According to further embodiments of the present invention, a program for using a computer to cause a substrate processing system to perform the steps (processes) of Appendix 1, or a computer-readable recording medium containing the program, is provided.

Claims

1. A substrate processing method comprising: (a) a step of forming a first film of an amorphous state of an undoped dopant on a substrate by supplying a first processing gas to the substrate; (b) a step of forming a second film of an amorphous state of a dopant-doped, which has a lower crystallization temperature than the first film, on the first film by supplying a second processing gas to the substrate; (c) a step of crystallizing the first film and the second film formed on the substrate by heating them; (d) a step of removing at least the second film by exposing a surface of the substrate to an etchant after crystallizing the first film and the second film; and (e) a step of oxidizing and modifying a portion where the dopant exists in the first film and the second film to an oxidized film which is easily etched in (d) after (c) is performed and before (d) is performed, wherein the first film is an amorphous silicon film and the second film is an amorphous silicon film.

2. The substrate processing method according to claim 1, wherein in (c), a portion of the dopant in the second film diffuses into the first film, in (d), a portion of the first film where the dopant in the second film diffuses is also removed, in (d), a surface of the first film where the dopant does not exist is exposed, in (c), crystallization of the second film is started prior to crystallization of the first film, in (c), crystallization of the second film is completed prior to crystallization of the first film, in (c), the first film is crystallized from a starting point of a crystalline grain of the second film, in (c), a crystalline state of the second film is inherited to the first film, in (c), a temperature of the substrate is set to 550°C or higher and 650°C or lower, in (a), the first film is formed to have a thickness which is larger than a thickness of the first film obtained after (d) is performed by an amount of a depth where the dopant diffuses from the second film into the first film in (c), in (a), the first film is formed to have a thickness which is only larger than a thickness of the first film obtained after (d) is performed by an amount of a depth where the dopant diffuses from the second film into the first film in (c), the second film is made to have a thickness which is larger than or equal to a thickness of the first film, the second film is made to have a thickness which is larger than a thickness of the first film, on a surface of the substrate, an oxidized film is formed, and in (a), the first film is formed on the oxidized film.

14. A method of manufacturing a semiconductor device comprising: (a) a step of forming a first film of an amorphous state of an undoped dopant on a substrate by supplying a first processing gas to the substrate; (b) a step of forming a second film of an amorphous state of a dopant-doped, which has a lower crystallization temperature than the first film, on the first film by supplying a second processing gas to the substrate; (c) a step of crystallizing the first film and the second film formed on the substrate by heating them; (d) a step of removing at least the second film by exposing a surface of the substrate to an etchant after crystallizing the first film and the second film; and ​ ​ ​ ​ ​ ​ ​ ​ 3. The substrate processing method as recited in claim 2, wherein, ​ 4. The substrate processing method as recited in claim 1, wherein, ​ 5. The substrate processing method as recited in claim 1, wherein, ​ 6. The substrate processing method as recited in claim 4, wherein, ​ 7. The substrate processing method as set forth in claim 4, wherein ​ 8. The substrate processing method as recited in claim 1, wherein, ​ 9. The substrate processing method as recited in claim 2, wherein, ​ 10. The substrate processing method as set forth in claim 2, wherein, ​ 11. The substrate processing method as set forth in claim 1, wherein ​ 12. The substrate processing method as set forth in claim 1, wherein, ​ 13. The substrate processing method as set forth in claim 1, wherein, ​ ​ ​ ​ ​ ​ (e) after (c) and before (d), oxidizing and modifying a portion of the dopant present in the first film and the second film into an oxidized film that is easily etched in (d), wherein the first film is an amorphous silicon film and the second film is an amorphous silicon film.

15. A substrate processing system, comprising: a first process gas supply system that supplies a first process gas to a substrate; a second process gas supply system that supplies a second process gas to the substrate; a heater that heats the substrate; an etchant exposure system that exposes the substrate to an etchant; a control unit configured to control the first process gas supply system, the second process gas supply system, the heater, and the etchant exposure system to perform the following processes: (a) a process of forming a first film of an undoped dopant in an amorphous state on a substrate by supplying the first process gas to the substrate; (b) a process of forming a second film of a dopant-doped amorphous state having a lower crystallization temperature than the first film on the first film by supplying the second process gas to the substrate; (c) a process of crystallizing the first film and the second film formed on the substrate by heating the first film and the second film; (d) a process of removing at least the second film by exposing a surface of the substrate to the etchant after crystallizing the first film and the second film; and (e) after (c) and before (d), oxidizing and modifying a portion of the dopant present in the first film and the second film into an oxidized film that is easily etched in (d), wherein the first film is an amorphous silicon film and the second film is an amorphous silicon film.

16. A computer-readable recording medium that records a program for causing a computer to cause a substrate processing system to perform the following steps: (a) a step of forming a first film of an undoped dopant in an amorphous state on a substrate by supplying a first process gas to the substrate; (b) a step of forming a second film of a dopant-doped amorphous state having a lower crystallization temperature than the first film on the first film by supplying a second process gas to the substrate; (c) a step of crystallizing the first film and the second film formed on the substrate by heating the first film and the second film; (d) a step of removing at least the second film by exposing a surface of the substrate to an etchant after crystallizing the first film and the second film; and (e) after (c) and before (d), a step of modifying a portion of the dopant present in the first film and the second film, wherein the first film is an amorphous silicon film and the second film is an amorphous silicon film. ​

Images