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

Abstract

The process includes (a) supplying a first raw material gas to a substrate provided with a recessed structure on a surface to form a first film having a prescribed adhesion on an inner face of the recessed structure; and (b) supplying a second raw material gas to the substrate to form a second film having an adhesion smaller than that of the first film on the first film.

Description

Technical Field

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

[0002] As part of the manufacturing process of semiconductor devices, there is sometimes a process of forming a film on the surface of a substrate (see, for example, Patent Documents 1 and 2).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-153776

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-216342 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The purpose of this disclosure is to provide a technique for reducing stress between patterns formed on the surface of a substrate when a film is embedded inside a concave structure of a substrate.

[0009] Methods for solving problems

[0010] According to one aspect of this disclosure, technology is provided for performing the following processes:

[0011] (a) A process of supplying a first raw material gas to a substrate having a concave structure on its surface to form a first film having a specified adhesion strength on the inner surface of the concave structure; and

[0012] (b) The process of supplying a second raw material gas to the substrate to form a second film on the first film having a weaker adhesion than the first film.

[0013] Invention Effects

[0014] According to this disclosure, when a film is embedded inside the concave structure of a substrate, the stress generated between patterns formed on the surface of the substrate can be reduced. Attached Figure Description

[0015] Figure 1 This is a schematic configuration diagram of a vertical processing furnace of a substrate processing apparatus preferred in one embodiment of the present disclosure, and is a diagram showing the processing furnace 202 portion in a longitudinal sectional view.

[0016] Figure 2This is a schematic diagram of a vertical processing furnace of a substrate processing apparatus preferred in one embodiment of this disclosure, and is based on... Figure 1 The AA-line sectional view shows part of the processing furnace 202.

[0017] Figure 3 This is a schematic configuration diagram of the controller 121 of a substrate processing apparatus preferably used in one embodiment of the present disclosure, and is a block diagram showing the control system of the controller 121.

[0018] Figure 4 This is a diagram illustrating the processing sequence in one manner as described in this disclosure.

[0019] Figure 5 This is a diagram illustrating a variation of the processing sequence in one manner of this disclosure.

[0020] Figure 6 This is a partially enlarged cross-sectional view of a substrate with a concave structure on its surface, which was used to form a film using a first raw material gas and embedded within the concave structure.

[0021] Figure 7 This is a partially enlarged cross-sectional view of a substrate with a concave structure on its surface, which underwent film formation using a second raw material gas and was embedded within the concave structure.

[0022] Figure 8 This is a partially enlarged cross-sectional view of a substrate with a concave structure on its surface, which has undergone film formation using a first raw material gas and a second raw material gas, and has been embedded within the concave structure.

[0023] Figure 9 This is a partially enlarged cross-sectional view of a substrate with a concave structure on its surface, which has undergone film formation using a first raw material gas and a second raw material gas, and has been embedded within the concave structure.

[0024] Figure 10 This is a graph illustrating the relationship between film thickness and adhesion in a film formed on a substrate. Detailed Implementation

[0025] <One way of publishing this text>

[0026] The following is mainly based on Figures 1-4 This is one way to illustrate the text of this disclosure. It should be noted that the accompanying drawings used in the following description are schematic, and the dimensional relationships and ratios of the elements shown in the drawings are not necessarily consistent with reality. Furthermore, the dimensional relationships and ratios of the elements are not necessarily consistent across multiple drawings.

[0027] (1) Composition of substrate processing device

[0028] 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 mounted by being supported on a retaining plate. The heater 207 also functions as an activation mechanism (excitation unit) that uses heat to activate (excite) the gas.

[0029] Inside the heater 207, a reaction tube 203 is arranged concentrically with 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 engages with the lower end of the reaction tube 203 to support the reaction tube 203. An O-ring 220a is provided between the manifold 209 and the reaction tube 203 as a sealing component. The reaction tube 203 is also vertically mounted like 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 part of the processing container. The processing chamber 201 is configured to accommodate a wafer 200 as a substrate. Processing of the wafer 200 is performed within the processing chamber 201.

[0030] Nozzles 249a and 249b, serving as a first supply section and a second supply section, are respectively installed in the processing chamber 201, penetrating the side wall of the manifold 209. Nozzles 249a and 249b are also referred to as the first nozzle and the second nozzle, respectively. Nozzles 249a and 249b are made of heat-resistant materials such as quartz or SiC. Gas supply pipes 232a and 232b are connected to nozzles 249a and 249b, respectively. Nozzles 249a and 249b are distinct nozzles, and are arranged adjacent to each other.

[0031] On gas supply pipes 232a and 232b, mass flow controllers (MFCs) 241a and 241b, serving as flow controllers (flow control units), and valves 243a and 243b, serving as on / off valves, are sequentially installed from the upstream side of the airflow. Gas supply pipes 232c to 232e are connected to gas supply pipe 232a at a position downstream of valve 243a. Gas supply pipe 232f is connected to gas supply pipe 232b at a position downstream of valve 243b. On gas supply pipes 232c to 232f, MFCs 241c to 241f and valves 243c to 243f are sequentially installed from the upstream side of the airflow. Gas supply pipes 232a to 232f are made of a metal material such as SUS.

[0032] like Figure 2 As shown, nozzles 249a and 249b are respectively arranged in a ring-shaped space between the inner wall of the reaction tube 203 and the wafer 200 when viewed from above, rising vertically from the lower part of the inner wall of the reaction tube 203 towards the arrangement direction of the wafer 200. That is, nozzles 249a and 249b 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. Gas supply holes 250a and 250b for supplying gas are respectively provided on the side of the nozzles 249a and 249b. Gas supply holes 250a and 250b open towards the center of the wafer 200 when viewed from above, and can supply gas to the wafer 200. Multiple gas supply holes 250a and 250b are provided from the lower part to the upper part of the reaction tube 203.

[0033] The first raw material gas is supplied from the gas supply pipe 232a to the processing chamber 201 via MFC 241a, valve 243a, and nozzle 249a.

[0034] Oxygen (O) gas, which is used as an oxidizing gas, is supplied into the processing chamber 201 from the gas supply pipe 232b via MFC 241b, valve 243b, and nozzle 249b.

[0035] The second raw material gas is supplied from the gas supply pipe 232c to the processing chamber 201 via MFC 241c, valve 243c, and nozzle 249a.

[0036] Hydrogen (H) gas, used as a reducing gas, is supplied into the processing chamber 201 via gas supply pipe 232d, MFC 241d, valve 243d, gas supply pipe 232a, and nozzle 249a. While the H gas alone cannot achieve oxidation, it plays a role in improving the efficiency of the oxidation process by reacting with O-containing gas under specific conditions during the substrate processing described later, thereby generating oxides such as atomic oxygen (O). Therefore, the H gas can be considered to be included within the oxidizing gas.

[0037] Inactive gas is supplied to the treatment chamber 201 through gas supply pipes 232e and 232f via MFCs 241e and 241f, valves 243e and 243f, gas supply pipes 232a and 232b, and nozzles 249a and 249b, respectively. The inactive gas functions as a purge gas, carrier gas, or dilution gas.

[0038] The first raw material gas supply system mainly consists of gas supply pipe 232a, MFC 241a, and valve 243a. The second raw material gas supply system mainly consists of gas supply pipe 232c, MFC 241c, and valve 243c.

[0039] The oxidizing gas supply system mainly consists of gas supply pipe 232b, MFC 241b, and valve 243b. The reducing gas supply system mainly consists of gas supply pipe 232d, MFC 241d, and valve 243d. Alternatively, gas supply pipe 232d, MFC 241d, and valve 243d can be included in the oxidizing gas supply system. Both the oxidizing and reducing gases are used as reactants in the substrate processing steps described later. In the substrate processing steps, the reactant gas used to form the first film on the substrate can be called the first reactant gas, and the reactant gas used to form the second film on the substrate can be called the second reactant gas. Therefore, the oxidizing gas supply system and the reducing gas supply system, or both, can be referred to as the reactant gas supply system (first reactant gas supply system, second reactant gas supply system).

[0040] The inactive gas supply system is mainly composed of gas supply pipes 232e, 232f, MFC241e, 241f, and valves 243e and 243f.

[0041] Both the raw material gas and the reaction gas are referred to as film-forming gases, and both the raw material gas supply system and the oxidation gas supply system are referred to as film-forming gas supply systems.

[0042] Any one or all of the aforementioned supply systems can be configured as an integrated supply system 248, which integrates valves 243a-243f, MFCs 241a-241f, etc. The integrated supply system 248 is configured such that it is connected to each of the gas supply pipes 232a-232f, and the controller 121 (described later) controls the supply of various substances (various gases) into the gas supply pipes 232a-232f, i.e., the opening and closing of valves 243a-243f, and flow adjustment based on MFCs 241a-241f, etc. The integrated supply system 248 is configured as an integrated unit, either integral or modular, allowing for assembly and disassembly of the gas supply pipes 232a-232f, etc., and enabling maintenance, replacement, and addition of the integrated supply system 248 at the unit level.

[0043] An exhaust port 231a is provided below the side wall of the reaction tube 203 to exhaust the atmosphere inside the processing chamber 201. The exhaust port 231a can also be provided from the lower part of the side wall 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. A vacuum pump 246, serving as a vacuum exhaust device, is connected to the exhaust pipe 231 via a pressure sensor 245 (pressure detector, pressure detection unit) and an APC (Auto Pressure Controller) valve 244 (pressure regulator, pressure adjustment unit). The APC valve 244 is configured to allow vacuum exhaust and vacuum exhaust stop within the processing chamber 201 by opening and closing the valve while the vacuum pump 246 is operating. Furthermore, the pressure inside the processing chamber 201 can be adjusted by regulating the valve opening based on the pressure information detected by the pressure sensor 245 while the vacuum pump 246 is operating. The exhaust system mainly consists of the exhaust pipe 231, the APC valve 244, and the pressure sensor 245. Alternatively, the vacuum pump 246 can be included in the exhaust system.

[0044] A sealing cover 219, serving as a furnace opening cover, is provided below the manifold 209 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. A rotation mechanism 267, which rotates the crystal boat 217 (described later), is provided below the sealing cover 219. The rotation shaft 255 of the rotation mechanism 267 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 move vertically via a crystal boat lift 115, which is provided outside the reaction tube 203 and serves as a lifting mechanism. The crystal boat lift 115 is configured as a transport device (transport mechanism), which moves the wafer 200 into the processing chamber 201 and out of the processing chamber 201 by raising and lowering the sealing cover 219.

[0045] A gate 219s, serving as a furnace opening cover, is provided below the manifold 209. This gate 219s can airtightly seal the lower opening of the manifold 209 while the sealing cover 219 is lowered to remove the crystal boat 217 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.

[0046] The crystal boat 217, serving as a substrate support, is configured to support multiple wafers (e.g., 25 to 200 wafers) 200 arranged horizontally and with their centers aligned in the vertical direction in a multi-layered manner, i.e., 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.

[0047] A temperature sensor 263, serving as a temperature detector, is installed inside the reaction tube 203. By adjusting the energizing 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.

[0048] like Figure 3As 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, configured as, for example, a touch panel, is connected to the controller 121. Furthermore, an external storage device 123 can be connected to the controller 121.

[0049] The storage device 121c is composed of, for example, flash memory, HDD (Hard Disk Drive), SSD (Solid State Drive), etc. The storage device 121c stores, in a readable manner, a control program that controls the operation of the substrate processing apparatus, and a process flow that describes the steps and conditions of the substrate processing described later. The process flow is a process that combines the steps of the substrate processing described later by using the controller 121 to obtain a predetermined result, and functions as a program. Hereinafter, the process flow, control program, etc., will also be referred to as a program. Furthermore, the process flow will be referred to simply as a process. In this specification, the term "program" is used in cases where only a process flow is included, cases where only a control program is included, or cases where both are included. RAM 121b is configured as a storage area (working area) for temporarily holding programs, data, etc., read by the CPU 121a.

[0050] I / O port 121d is connected to the aforementioned MFC241a~241f, valves 243a~243f, 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.

[0051] CPU 121a is configured to read and execute control programs from storage device 121c, and to read processes from storage device 121c based on inputs such as operation commands from input / output device 122. CPU 121a is configured to control the following actions according to the read processes: flow rate adjustment of various substances (various gases) using MFCs 241a to 241f, opening and closing of valves 243a to 243f, opening and closing of APC valve 244, pressure adjustment using APC valve 244 based on pressure sensor 245, starting and stopping of vacuum pump 246, temperature adjustment of heater 207 based on temperature sensor 263, rotation and speed adjustment of crystal boat 217 using rotating mechanism 267, lifting and lowering of crystal boat 217 using crystal boat elevator 115, opening and closing of gate 219s using gate opening and closing mechanism 115s, etc.

[0052] The controller 121 can be configured to install the aforementioned program stored in the external storage device 123 onto 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 memory, and a semiconductor memory such as an SSD. The storage device 121c and the external storage device 123 are configured in the form of a recording medium that can be read by a computer. Hereinafter, they will also be referred to collectively as recording media. In this specification, the term "recording medium" is used in cases where only the storage device 121c is included, cases where only the external storage device 123 is included, or cases where both are included. It should be noted that providing a program to a computer can also be done without using the external storage device 123, but using communication means such as the Internet or a dedicated line.

[0053] (2) Substrate processing process

[0054] An example of a processing sequence in which the aforementioned substrate processing apparatus is used as a step in the manufacturing process of a semiconductor device to form a film inside a concave structure by embedding the concave structure provided on the surface of a wafer 200, which serves as a substrate. This example primarily uses... Figure 4 The following description will explain the operation of each part constituting the substrate processing apparatus, which is controlled by controller 121.

[0055] The inner surface of the concave structure disposed on the surface of the wafer 200 has opposing side surfaces and a bottom surface. The concave structure is configured such that the distance between the side surfaces of the lower part of the concave structure is shorter (narrower) than the distance between the side surfaces of the upper part of the concave structure, which is called a cone shape.

[0056] Figure 4 The processing sequence shown includes:

[0057] Step A: A first raw material gas is supplied to the wafer 200 having a concave structure on its surface, forming a first film with a specified adhesion on the inner surface of the concave structure; and

[0058] Step B: A second raw material gas is supplied to the wafer 200 to form a second film with a weaker adhesion than the first film on the first film.

[0059] In step A,

[0060] The cycle of supplying the first raw material gas and the first reaction gas is performed at different times is executed a specified number of times (m times, where m is an integer greater than or equal to 1).

[0061] In step B,

[0062] The cycle of supplying the second raw material gas and the second reaction gas, which are not performed simultaneously, is executed a specified number of times (n times, where n is an integer greater than or equal to 1).

[0063] For convenience, the above processing order is sometimes represented as follows in this specification. The same expression is also used in the following descriptions of variations and other methods.

[0064] (First feed gas → First reactant gas) × m → (Second feed gas → Second reactant gas) × n

[0065] In this specification, the term "wafer" is used to mean either the wafer itself or a laminate of a wafer and a specified layer or film formed on its surface. The term "surface of the wafer" is used to mean either the surface of the wafer itself or the surface of a specified layer, etc., formed on the wafer. The phrase "forming a specified layer on the wafer" is used to mean either forming the specified layer directly on the surface of the wafer itself or forming the specified layer on top of a layer, etc., formed on the wafer. The term "substrate" is used in the same way as "wafer."

[0066] (Wafer filling and crystal boat loading)

[0067] When multiple wafers 200 are loaded into the wafer boat 217 (wafer filling), the gate opening and closing mechanism 115s moves the gate 219s, opening the lower end 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 lift 115 and moved into the processing chamber 201 (crystal boat loading). In this state, the sealing cover 219 seals the lower end of the manifold 209 by means of an O-ring 220b.

[0068] (Pressure and temperature adjustment)

[0069] Vacuum pump 246 performs vacuum venting (pressure reduction venting) to achieve the desired pressure (vacuum level) within processing chamber 201, i.e., the space where wafer 200 is located. At this time, the pressure within processing chamber 201 is measured by pressure sensor 245, and APC valve 244 is controlled based on this measured pressure information. Additionally, heater 207 heats the wafer 200 within processing chamber 201 to achieve the desired processing temperature. The energizing state of heater 207 is controlled based on temperature information detected by temperature sensor 263 to achieve the desired temperature distribution within processing chamber 201. Furthermore, rotation of wafer 200 is initiated using rotation mechanism 267. Venting within processing chamber 201, heating of wafer 200, and rotation all continue at least until the processing of wafer 200 is completed.

[0070] (OH-terminal formation)

[0071] In this step, a first reaction gas (pre-flow) is supplied to the wafer 200 inside the processing chamber 201.

[0072] Specifically, valve 243b is opened, allowing the first reactive gas to flow into the gas supply pipe 232b. The flow rate of the first reactive gas is adjusted by MFC 241b, supplied into the processing chamber 201 via nozzle 249b, and discharged from exhaust port 231a. At this time, the first reactive gas is supplied to the wafer 200 (reactive gas supply). Then, valves 243e and 243f are opened, supplying inactive gas into the processing chamber 201 via nozzles 249a and 249b, respectively. It should be noted that the supply of inactive gas may not be necessary.

[0073] Examples of processing conditions in this step include:

[0074] Processing temperature: 400–900℃, preferably 600–700℃

[0075] Processing pressure: 0.1–30 Torr, preferably 0.2–20 Torr

[0076] First reaction gas supply flow rate: 0.1–20 slm, preferably 5–12 slm

[0077] First reaction gas supply time: 100-1000 seconds, preferably 200-1000 seconds

[0078] Inactive gas supply flow rate (per gas supply pipe): 0–3.0 slm.

[0079] It should be noted that the numerical ranges expressed in this specification, such as "400~900℃", mean that the lower and upper limits are included within this range. Therefore, for example, "400~900℃" means "above 400℃ and below 900℃". The same applies to other numerical ranges. Furthermore, the processing temperature in this specification means the temperature of the wafer 200 or the temperature inside the processing chamber 201, and the processing pressure means the pressure inside the processing chamber 201. Additionally, "Gas supply flow rate: 0 slm" means that the gas is not supplied. These also apply to the following descriptions.

[0080] By performing this step under the above-described processing conditions, hydroxyl capping (OH capping) can be formed over the entire surface area of ​​the wafer 200. The OH capping present on the surface of the wafer 200 functions as adsorption sites for the raw material gas, i.e., adsorption sites for the molecules and atoms constituting the raw material gas, in the film formation process described later.

[0081] After OH is formed, valve 243b is closed, stopping the supply of the first reactant gas to the processing chamber 201. Furthermore, a vacuum is applied to the processing chamber 201 to remove any remaining gaseous substances. At this time, valves 243e and 243f are opened, supplying inactive gas to the processing chamber 201 via nozzles 249a and 249b. The inactive gas supplied from nozzles 249a and 249b acts as a purging gas, thereby purging the processing chamber 201.

[0082] Examples of treatment conditions during purging include:

[0083] Inactive gas supply flow rate (per gas supply pipe): 0.5–10 slm

[0084] Inactive gas supply time: 1 to 30 seconds, preferably 5 to 20 seconds.

[0085] As inert gases, rare gases such as nitrogen (N2), argon (Ar), helium (He), neon (Ne), and xenon (Xe) can be used. More than one of these gases can be used as an inert gas. This also applies to the steps described later.

[0086] (Step A: First membrane formation)

[0087] Then, execute the following steps a1 and a2 in sequence.

[0088] [Step a1]

[0089] In this step, a first raw material gas is supplied to the wafer 200 inside the processing chamber 201.

[0090] Specifically, valve 243a is opened, allowing the first raw material gas to flow into the gas supply pipe 232a. The first raw material gas, with its flow rate adjusted by MFC 241a, is supplied into the processing chamber 201 via nozzle 249a and exhausted from exhaust port 231a. At this time, the first raw material gas is supplied to the wafer 200 (raw material gas supply). Then, valves 243e and 243f are opened, supplying inactive gas into the processing chamber 201 via nozzles 249a and 249b, respectively. It should be noted that the supply of inactive gas may not be implemented.

[0091] Examples of processing conditions in this step include:

[0092] Processing temperature: 400–900℃, preferably 600–700℃

[0093] Processing pressure: 0.1–10 Torr, preferably 0.2–10 Torr

[0094] The first raw material gas supply flow rate is 0.01–1 slm, preferably 0.1–0.5 slm.

[0095] First raw material gas supply time: 1-100 seconds, preferably 15-20 seconds

[0096] Inactive gas supply flow rate (per gas supply tube): 0–10.0 slm.

[0097] By supplying the wafer 200 with a silane gas containing amino and alkoxy groups, as described later, under the aforementioned processing conditions, the amino groups can be removed from the silicon (Si) contained in the first raw material gas without the alkoxy groups being removed. Furthermore, Si, while maintaining its bond with the alkoxy groups, can be adsorbed onto the surface of the wafer 200 (chemisorption). That is, Si can be adsorbed onto a portion of the adsorption sites on the surface of the wafer 200 while alkoxy groups are bonded to the three bonds of Si. In this way, a first layer (Si-containing layer) containing alkoxy groups bonded to Si can be formed on the outermost surface of the wafer 200.

[0098] Furthermore, by performing this step under the aforementioned processing conditions, it is possible to prevent the amino groups detached from the Si contained in the first raw material gas from adsorbing onto the surface of the wafer 200. As a result, the first layer formed on the wafer 200 does not contain amino groups detached from the Si contained in the first raw material gas. That is, the first layer formed on the wafer 200 can be a layer with low amino content and low levels of impurities derived from amino groups, such as carbon (C) and nitrogen (N).

[0099] In this step, by pre-filling (pre-blocking) the bonding bonds of Si adsorbed on the surface of wafer 200 with alkoxy groups, the adsorption of at least one atom or molecule onto Si adsorbed on the surface of wafer 200 is prevented. Furthermore, by using the alkoxy groups bonded to Si adsorbed on the surface of wafer 200 as steric hindrances, the adsorption of at least one atom or molecule onto adsorption sites (OH-terminated) on the surface of wafer 200 surrounding the Si adsorbed on the surface of wafer 200 is prevented. Therefore, in this step, the adsorption sites (OH-terminated) on the surface of wafer 200 surrounding the Si adsorbed on the surface of wafer 200 are maintained.

[0100] In this step, it is preferable to continuously supply the first raw material gas until the adsorption reaction (chemisorption reaction) of Si on the surface of the wafer 200 is saturated. Even with the continuous supply of the first raw material gas, the alkoxy groups bonded to Si will act as steric hindrances, thereby enabling Si to be discontinuously adsorbed on the surface of the wafer 200. Specifically, Si can be adsorbed on the surface of the wafer 200 in a manner that results in a thickness less than a single atomic layer.

[0101] When the adsorption reaction saturates the adsorption of Si onto the surface of wafer 200, the surface of wafer 200 is covered by alkoxy groups bonded to Si, and a portion of the surface of wafer 200 remains unconsumed as adsorption sites (OH-terminated). When the adsorption reaction saturates the adsorption of Si onto the surface of wafer 200, the layer composed of Si adsorbed onto the surface of wafer 200 becomes a discontinuous layer with a thickness less than a single atomic layer.

[0102] After the first layer is formed, valve 243a is closed to stop the supply of the first raw material gas to the processing chamber 201. Furthermore, the gas and other gases remaining in the processing chamber 201 are removed from the processing chamber 201 by using the same processing sequence and processing conditions as those used in the purging process for OH end-capping.

[0103] As the first raw material gas, for example, a gas having a molecular structure in which alkoxy and amino groups are bonded to Si, which is the main element constituting the film formed on the wafer 200.

[0104] Alkoxy groups have a structure formed by the bonding of an alkyl group (R) to an oxygen (O) atom and are monovalent functional groups represented by the structural formula -OR. Alkoxy groups (-OR) include methoxy (-OMe), ethoxy (-OEt), propoxy (-OPr), and butoxy (-OBu), etc. Alkoxy groups are not limited to the above-mentioned straight-chain alkoxy groups; they can also be branched alkoxy groups such as isopropoxy, isobutoxy, sec-butoxy, and tert-butoxy. Additionally, alkyl groups (-R) include methyl (-Me), ethyl (-Et), propyl (-Pr), and butyl (-Bu), etc. Alkyl groups are not limited to the above-mentioned straight-chain alkyl groups; they can also be branched alkyl groups such as isopropyl, isobutyl, sec-butyl, and tert-butyl.

[0105] The amino group has a structure formed by removing hydrogen (H) from any of ammonia (NH3), primary amines, and secondary amines, and is a monovalent functional group represented by any of the structural formulas -NH2, -NHR, and -NRR'. R and R' shown in the structural formula are alkyl groups including methyl, ethyl, propyl, and butyl. R and R' are not only straight-chain alkyl groups as described above, but can also be branched alkyl groups such as isopropyl, isobutyl, sec-butyl, and tert-butyl. R and R' can be the same alkyl group or different alkyl groups. Examples of amino groups include dimethylamino (-N(CH3)2) and diethylamino (-N(C2H5)2).

[0106] As the first raw material gas, dialkylaminotrialkoxysilane gases such as (dimethylamino)triethoxysilane ([(CH3)2N]Si(OC2H5)3), (diethylamino)triethoxysilane ([(C2H5)2N]Si(OC2H5)3), (dimethylamino)trimethoxysilane ([(CH3)2N]Si(OCH3)3), and (diethylamino)trimethoxysilane ([(C2H5)2N]Si(OCH3)3) can be used. Dialkylaminotrialkoxysilane gases can be used as silane gases containing both amino and alkoxy groups. The Si contained in the above gases has four bonds, with alkoxy groups (methoxy, ethoxy) bonded to three of the four bonds, and an amino group (dimethylamino, diethylamino) bonded to the remaining bond. Therefore, organic gases containing amino groups in their molecular structure are preferably used as the first raw material gas. One or more of the above-mentioned gases can be used as the primary raw material gas.

[0107] As the first raw material gas, aminosilane-based gases such as tetra(dimethylamino)silane (Si[N(CH3)2]4, abbreviated as 4DMAS), tri(dimethylamino)silane (Si[N(CH3)2]3H, abbreviated as 3DMAS), bis(diethylamino)silane (Si[N(C2H5)2]2H2, abbreviated as BDEAS), bis(tert-butylamino)silane (SiH2[NH(C4H9)]2, abbreviated as BTBAS), and (diisopropylamino)silane (SiH3[N(C3H7)2], abbreviated as DIPAS) can also be used. One or more of the above-mentioned gases can be used as the first raw material gas.

[0108] [Step a2]

[0109] In this step, an oxygen-containing gas is supplied to the wafer 200 in the processing chamber 201 as the first reaction gas.

[0110] Specifically, valve 243b is opened, allowing the first reactive gas to flow into the gas supply pipe 232b. The flow rate of the first reactive gas is adjusted by MFC 241b, supplied into the processing chamber 201 via nozzle 249b, and discharged from exhaust port 231a. At this time, the first reactive gas is supplied to the wafer 200 (reactive gas supply). Then, valves 243e and 243f are opened, supplying inactive gas into the processing chamber 201 via nozzles 249a and 249b, respectively. It should be noted that the supply of inactive gas may not be necessary.

[0111] Examples of processing conditions in this step include:

[0112] Processing pressure: 0.1–30 Torr, preferably 0.2–20 Torr

[0113] First reaction gas supply flow rate: 0.1–20 slm, preferably 5–12 slm

[0114] First reaction gas supply time: 1–200 seconds, preferably 150–190 seconds

[0115] Inactive gas supply flow rate (per gas supply pipe): 0–3.0 slm.

[0116] Other processing conditions can be set to the same conditions as those used in step a1 when supplying the first raw material gas.

[0117] By performing this step under the above-described processing conditions, alkoxy groups bonded to the Si contained in the first layer can be removed from the first layer, for example. By supplying an oxidizing gas (containing O gas) to the wafer 200 as the first reaction gas under the above-described processing conditions, at least a portion of the first layer formed on the wafer 200 can be oxidized (modified), forming a silicon oxide layer (SiO layer) containing Si and O as the second layer. The second layer becomes a layer that does not contain alkoxy groups, i.e., a layer that does not contain impurities such as C. In addition, the surface of the second layer becomes a state with OH-terminated due to the oxidation treatment based on the O-containing gas, i.e., a state with adsorption sites. It should be noted that the impurities such as C removed from the first layer constitute gaseous substances such as carbon dioxide (CO2) and are discharged from the processing chamber 201. Thus, the second layer (SiO layer) becomes a layer with fewer impurities such as C compared to the first layer (containing Si layer) formed in step a1.

[0118] After the second layer is formed, valve 243b is closed to stop the supply of the first reaction gas to the processing chamber 201. Then, using the same processing sequence and conditions as in step a1, any remaining gases in the processing chamber 201 are removed (purged).

[0119] As the first reacting gas, gases such as oxygen (O2), ozone (O3), water vapor (H2O), hydrogen peroxide (H2O2), nitric oxide (NO), nitrous oxide (N2O), carbon monoxide (CO), nitrogen dioxide (NO2), and plasma-excited O2 can be used. * O-containing gases, such as oxygen-containing gases, can be used as the first reactant gas. One or more of the above-mentioned gases can be used.

[0120] [Number of times stipulated for implementation]

[0121] By performing steps a1 and a2 as described above a predetermined number of times (m times, where m is an integer greater than or equal to 1) at different times, i.e. asynchronously, a first SiO film with a predetermined composition and thickness can be formed on the wafer 200. Preferably, the above-described cycle is repeated multiple times. That is, it is preferable that the thickness of the second layer (SiO layer) formed in one cycle is smaller than the desired film thickness, and the above-described cycle is repeated multiple times until the thickness of the first SiO film formed by stacking the second layer reaches the desired film thickness.

[0122] It should be noted that in step A, it is preferable to form the first SiO film while maintaining the state (film thickness) in which the first SiO films formed on opposite sides of the concave structure on the surface of the wafer 200 do not contact each other.

[0123] In addition, in step A, it is preferable to set the ratio of the thickness of the first SiO film to the total thickness of the first SiO film and the thickness of the second SiO film, which will be described later as the second film, to 50% or less.

[0124] In addition, in step A, it is preferable to set the ratio of the thickness of the first SiO film to the total thickness of the first SiO film and the thickness of the second SiO film, which will be described later as the second film, to 10% or more.

[0125] It should be noted that the step coverage of the first SiO film is higher than that of the second SiO film, which will be described later as the second film. This is because, in step a1, as described above, under the condition that the adsorption reaction of the Si contained in the first raw material gas adsorbed onto the surface of the wafer 200 is saturated, the layer composed of Si adsorbed onto the surface of the wafer 200 can be made into a discontinuous layer with a thickness less than a single atomic layer. That is, in step a1, whether it is the side surface near the upper part of the concave structure of the wafer 200 or the bottom of the concave structure, the formation of the first layer with a non-uniform thickness of more than a single atomic layer can be suppressed, and the first layer is formed into a layer with a uniform thickness and excellent step coverage. In this case, in step a2, the O-containing gas can react with the first layer with excellent step coverage, for example, on the side surface near the upper part of the concave structure of the wafer 200 and at the bottom of the concave structure, as a result, the first SiO film can become a film with excellent step coverage.

[0126] Furthermore, the first SiO film has the characteristic of maintaining a good level of substrate oxidation compared to the second SiO film, which will be described later as the second film. The reason why the substrate oxidation level can be maintained well during the formation of the first SiO film compared to the formation of the second SiO film is that, in step a2, the first layer is oxidized under processing conditions where the oxidizing power is weaker than in step b2, which will be described later. Specifically, this is because in step a2, the first reactant gas used is a gas with weaker oxidizing power than the second reactant gas used in step b2, which will be described later. As a result, the oxidation of the substrate, i.e., the oxidation of the surface of the wafer 200 in contact with the first SiO film, can be sufficiently suppressed. By suppressing the oxidation of the surface of the wafer 200, the associated effects such as a decrease in device characteristics can be reduced.

[0127] (Step B: Second membrane formation)

[0128] Then, execute the following steps b1 and b2 in sequence.

[0129] [Step b1]

[0130] In this step, a second raw material gas is supplied to the wafer 200 inside the processing chamber 201.

[0131] Specifically, valve 243c is opened, allowing the second raw material gas to flow into the gas supply pipe 232c. The flow rate of the second raw material gas is adjusted by MFC 241c, and it is supplied into the processing chamber 201 via nozzle 249a and discharged from exhaust port 231a. At this time, the second raw material gas is supplied to the wafer 200 (raw material gas supply). At this time, valves 243e and 243f are opened, supplying inactive gas into the processing chamber 201 via nozzles 249a and 249b, respectively. It should be noted that the supply of inactive gas may not be implemented.

[0132] Examples of processing conditions in this step include:

[0133] Second raw material gas supply flow rate: 0.01~1 slm, preferably 0.1~0.5 slm

[0134] The second raw material gas supply time is 1 to 100 seconds, preferably 15 to 20 seconds.

[0135] Other processing conditions can be set to the same conditions as those used in step a1 when supplying the first raw material gas.

[0136] By supplying a chlorosilane-based gas, as described later, to the wafer 200 under the aforementioned processing conditions as a second raw material gas, a Si-containing layer containing chlorine (Cl) can be formed as a third layer on the outermost surface of the wafer 200, which serves as a substrate. The Si-containing layer containing Cl is formed through the physical or chemical adsorption of molecules of the chlorosilane-based gas onto the outermost surface of the wafer 200, the physical or chemical adsorption of molecules of substances obtained from the partial decomposition of the chlorosilane-based gas onto the outermost surface of the wafer 200, or the deposition of Si generated from the thermal decomposition of the chlorosilane-based gas onto the outermost surface of the wafer 200. The Si-containing layer containing Cl can be an adsorption layer (physical adsorption layer, chemical adsorption layer) of molecules of the chlorosilane-based gas or molecules of substances obtained from the partial decomposition of the chlorosilane-based gas, or it can be a deposited layer of Si containing Cl. It should be noted that, under the above processing conditions, the molecules of chlorosilane-based gases and the molecules of substances obtained from the partial decomposition of chlorosilane-based gases are predominantly (preferably) generated by physical adsorption and chemical adsorption on the outermost surface of the wafer 200, while the deposition of Si based on the thermal decomposition of chlorosilane-based gases is minimal or almost non-existent. That is, under the above processing conditions, the third layer (containing the Si layer) overwhelmingly comprises a large amount of adsorption layers (physical adsorption layer, chemical adsorption layer) of molecules of chlorosilane-based gases and molecules of substances obtained from the partial decomposition of chlorosilane-based gases, and minimally comprises or almost completely excludes the deposition layer of Si containing Cl.

[0137] After the third layer is formed, valve 243b is closed to stop the supply of the first reaction gas to the processing chamber 201. Then, using the same processing sequence and conditions as in step a1 (purging), any remaining gases in the processing chamber 201 are removed from the processing chamber 201 (purging).

[0138] As the second raw material gas, a silane-based gas, such as silicon (Si), can be used. This silane-based gas contains silicon (Si), which is the main element constituting the film formed on the wafer 200. As the silane-based gas, a gas containing Si and a halogen, such as a halosilane-based gas, can be used. Halogens include chlorine (Cl), fluorine (F), bromine (Br), iodine (I), etc. As the halosilane-based gas, the aforementioned chlorosilane-based gas containing Si and Cl can be used.

[0139] As the second raw material gas, chlorosilane-based gases such as tetrachlorosilane (SiCl4, abbreviated as STC), hexachlorosilane (Si2Cl6, abbreviated as HCDS), trichlorosilane (SiHCl3, abbreviated as TCS), dichlorosilane (SiH2Cl2, abbreviated as DCS), and monochlorosilane (SiH3Cl, abbreviated as MCS) can be used. Thus, inorganic gases that do not contain amino groups in their molecular structure can be used as the second raw material gas. One or more of the above-mentioned gases can be used as the second raw material gas.

[0140] In addition to chlorosilane-based gases, other suitable raw material gases include fluorosilane-based gases such as silicon tetrafluoride (SiF4) and difluorosilane (SiH2F2), bromosilane-based gases such as silicon tetrabromide (SiBr4) and dibromosilane (SiH2Br2), and iodosilane-based gases such as silicon tetraiodide (SiI4) and diiodosilane (SiH2I2). One or more of these gases can be used as the raw material gas.

[0141] [Step b2]

[0142] In this step, O-containing gas and H-containing gas are supplied to the wafer 200 in the processing chamber 201 as the second reaction gas.

[0143] Specifically, valves 243b and 243d are opened, allowing H-containing gas and O-containing gas to flow into gas supply pipes 232a and 232b, respectively. The H-containing gas and O-containing gas flowing in gas supply pipes 232a and 232b are adjusted in flow by MFCs 241a and 241b, and supplied to processing chamber 201 via nozzles 249a and 249b. The O-containing gas and H-containing gas mix and react within processing chamber 201, and then are discharged from exhaust port 231a. At this time, a moisture-free oxide (H2O) containing atomic oxygen (O) is supplied to wafer 200, generated by the reaction of O-containing gas and H-containing gas (supplying O-containing gas and H-containing gas). At this time, valves 243d and 243e are opened, supplying inactive gas into processing chamber 201 via nozzles 249a and 249b. It should be noted that the supply of inactive gas may not be implemented.

[0144] Examples of processing conditions in this step include:

[0145] Processing pressure: less than atmospheric pressure, preferably 0.1 to 20 Torr, more preferably 0.2 to 0.8 Torr

[0146] O-containing gas supply flow rate: 0.1–10 slm, preferably 0.5–10 slm

[0147] H-containing gas supply flow rate: 0.01–5 slm, preferably 0.1–1.5 slm

[0148] Gas supply time: 1–200 seconds, preferably 15–50 seconds

[0149] Inactive gas supply flow rate (per gas supply pipe): 0-10 slm.

[0150] Other processing conditions can be set to the same conditions as those used in step a1 when supplying the first raw material gas.

[0151] By performing this step under the aforementioned processing conditions, at least a portion of the third layer formed on wafer 200 is oxidized (modified) to form a silicon oxide layer (SiO layer) containing Si and O as the fourth layer. During the formation of the fourth layer (SiO layer), impurities such as Cl contained in the third layer (Si-containing layer) are converted into at least Cl-containing gaseous substances during the modification reaction of the Si-containing layer based on O-containing gas and H-containing gas, and are discharged from the processing chamber 201. Thus, the fourth layer becomes a layer with fewer impurities such as Cl compared to the third layer formed in step b1. Furthermore, the surface of the fourth layer becomes OH-terminated due to the oxidation treatment based on O-containing gas and H-containing gas, i.e., it becomes a state with adsorption sites.

[0152] By simultaneously supplying O-containing gas and H-containing gas into the processing chamber 201 under the aforementioned conditions, the O-containing gas and H-containing gas are thermally activated (excited) under a heated, reduced-pressure atmosphere using non-plasma, thereby generating an oxygen-free (H2O) oxide species containing atomic oxygen (O). Furthermore, the aforementioned oxidation (modification) treatment is primarily performed using this oxide species. According to this oxidation treatment, the oxidizing power can be significantly increased compared to step a2 where only O-containing gas is supplied. That is, by simultaneously adding O-containing gas and H-containing gas under a reduced-pressure atmosphere, a significant increase in oxidizing power can be achieved compared to the case where only O-containing gas is supplied.

[0153] After the fourth layer is formed, valves 243b and 243d are closed to stop the supply of O-containing gas and H-containing gas to the processing chamber 201, respectively. Then, using the same processing sequence and conditions as in step a1, the gases remaining in the processing chamber 201 are removed (purged).

[0154] As the second reactant gas, i.e., an O-containing gas and a H-containing gas (O-containing gas + H-containing gas), examples such as O2 gas + hydrogen (H2) gas, ozone (O3) gas + H2 gas, hydrogen peroxide (H2O2) gas + H2 gas, and water vapor (H2O) gas + H2 gas can be used. In this case, as the H-containing gas, deuterium (…) can also be used instead of H2 gas. 2 H2 gas. It should be noted that in this specification, the description of "O2 gas + H2 gas" together means a mixture of H2 gas and O2 gas. When supplying a mixed gas, the two gases can be mixed in the supply pipe (premixed) 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 then mixed in the processing chamber 201 (postmixed). One or more of the above-described methods can be used as the second reactant gas.

[0155] Alternatively, in this step, at least one of the gases containing O and H can be plasma-excited before being supplied. For example, plasma-excited O2 gas (O2... * ) and unexcited H2 gas (H2) * It can also supply O2 gas that has not been excited by plasma and H2 gas that has been excited by plasma, as well as O2 gas that has been excited by plasma and H2 gas that has been excited by plasma.

[0156] [Number of times stipulated for implementation]

[0157] By performing steps b1 and b2 as described above a predetermined number of times (n times, where n is an integer greater than or equal to 1) at different times, i.e. asynchronously, a second SiO film with a predetermined composition and thickness can be formed on the wafer 200. Preferably, the above cycle is repeated multiple times. That is, it is preferable to make the thickness of the fourth layer (SiO layer) formed by performing the above cycle once smaller than the desired film thickness, and to repeat the above cycle multiple times until the thickness of the second SiO film formed by stacking the fourth layer reaches the desired film thickness.

[0158] It should be noted that in step B, the second SiO film is preferably formed until at least a portion of the opposing second SiO films formed on the first SiO film come into contact with each other.

[0159] In addition, in step B, it is preferable to form a second SiO film until the entire concave structure of the wafer 200 is filled by the first SiO film and the second SiO film.

[0160] (Post-purging and atmospheric pressure recovery)

[0161] After the process of forming a second SiO film of the desired thickness on the wafer 200 is completed, inert gases are supplied as purge gases into the processing chamber 201 through nozzles 249a and 249b, and discharged 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), restoring the pressure inside the processing chamber 201 to atmospheric pressure (atmospheric pressure restoration).

[0162] (Crystal boat unloading and chip removal)

[0163] Next, 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).

[0164] (3) Effects of this method

[0165] According to this method, one or more of the effects shown below can be obtained.

[0166] (a) By performing steps A and B, it is possible to suppress the occurrence of phenomena such as collapse and deformation of patterns formed on the surface of wafer 200 (hereinafter, these are also referred to as pattern collapse), wherein, in step A, a first raw material gas is supplied to wafer 200 on which a concave structure is provided on the surface, and a first SiO film with a specified adhesion is formed on the inner surface of the concave structure; in step B, a second raw material gas is supplied to wafer 200, and a second SiO film with an adhesion force smaller than that of the first SiO film is formed on the first SiO film.

[0167] This is because, in the aforementioned substrate processing steps, when only the first raw material gas is used as the raw material gas and only the first SiO film, which has a stronger adhesion than the second SiO film, is used for embedding into the interior of the concave structure, during the formation of the first SiO film, when the surfaces of the first SiO films formed on the inner surface of the concave structure come into contact with each other, these films tend to adhere to each other with strong force (pull each other). Thus, the stress applied to the concave structure, i.e., the mutual pulling force generated between the opposing inner surfaces within the concave structure, increases, thereby causing pattern collapse (see reference). Figure 6 ).

[0168] In this method, not only is film formation using a first raw material gas performed, but film formation using a second raw material gas is also combined to form a second SiO film on top of the first SiO film, which has a weaker adhesion than the first SiO film. Therefore, compared to the case where only the first SiO film is used for embedding into the interior of the concave structure, the stress applied to the concave structure when the surfaces of the films formed on the inner surface of the concave structure come into contact with each other can be reduced, and pattern collapse can be suppressed (see reference). Figure 8 According to this method, in step B, even when the second SiO film is formed until the entire concave structure is filled by the first SiO film and the second SiO film, pattern collapse can be suppressed.

[0169] In this specification, "adhesion" primarily refers to the intermolecular attraction acting on the film surface based on van der Waals forces, etc. Additionally, "pattern collapse" refers to the phenomenon where adjacent patterns approach each other in a mutually dependent manner, causing the patterns to break or peel off from the base, depending on the circumstances.

[0170] (b) In step A, even when an organic gas is supplied as the first raw material gas, the occurrence of pattern collapse can be suppressed by supplying an inorganic gas as the second raw material gas in step B.

[0171] This is because the molecular weight of the first raw material gas, which is an organic gas, tends to be larger than that of the second raw material gas, which is an inorganic gas. Consequently, the molecular weight of the surface molecules of the first SiO film becomes larger than that of the surface molecules of the second SiO film. The larger the molecular weight of the molecules constituting the film surface, the greater the adhesion of the film tends to be. Therefore, the adhesion of the first SiO film is greater than that of the second SiO film (refer to...). Figure 10 In this method, as described above, not only is film formation performed using the first raw material gas, but film formation is also performed by combining the use of the second raw material gas, thereby suppressing the occurrence of pattern collapse.

[0172] (c) In step A, while maintaining the state in which the first SiO films formed on opposite sides of the concave structure do not contact each other, the first SiO film is formed. In step B, a second SiO film is formed on the first SiO film until at least a portion of the opposing second SiO films contact each other. That is, the films that are embedded in the concave structure contact each other through the second SiO film, which has a weaker adhesion, rather than through the first SiO film with a stronger adhesion. As a result, compared to the case where the first SiO films, which have a stronger adhesion than the second SiO film, contact each other, the stress applied to the concave structure can be reduced. As a result, pattern collapse can be suppressed.

[0173] (d) Even when the concave structure provided on the surface of the wafer 200 is configured as a so-called cone shape, where the distance between the sides at the lower part of the concave structure is shorter than the distance between the sides at the upper part of the concave structure, pattern collapse can be suppressed.

[0174] This is because both the first and second SiO films tend to have greater adhesion the thinner they are (see reference). Figure 10 Here, when the concave structure is configured as a cone as described above, the distance between the opposing sides is shorter (narrower) near the bottom of the concave structure compared to the area near the top. Therefore, during the formation of the first SiO film, the first SiO films formed on the side near the bottom of the concave structure are in contact with each other with a thickness greater than that of the first SiO films formed on the side near the top, i.e., with greater adhesion. This raises concerns about applying significant stress to the concave structure. Consequently, pattern collapse is prone to occur, starting near the bottom of the concave structure. In this method, in step A, the first SiO film is formed while maintaining a state where the first SiO films formed on the opposing sides within the concave structure do not contact each other, thus suppressing the occurrence of pattern collapse.

[0175] (e) By setting the ratio of the thickness of the first SiO film to the total thickness of the first SiO film and the second SiO film (the thickness of the stacked SiO films) to 50% or less, it is possible to prevent the surfaces of the first SiO films formed on the inner surface of the concave structure from contacting each other, thereby suppressing pattern collapse. If the ratio of the thickness of the first SiO film is greater than 50%, it is impossible to prevent the surfaces of the first SiO films formed on the inner surface of the concave structure from contacting each other, and the possibility of pattern collapse increases.

[0176] (f) By making the step coverage of the first SiO film formed in step A higher than that of the second SiO film formed in step B, the occurrence of voids and seams in the concave structure can be suppressed.

[0177] This is because, in the aforementioned substrate processing steps, when only the second raw material gas is used as the raw material gas and only a second SiO film with a lower step coverage than the first SiO film is used for embedding inside the concave structure, the second SiO film grows locally thick near the upper part of the concave structure. Before the embedding inside the concave structure is completed, the upper part of the concave structure is blocked. As a result, gaps and seams are generated within the concave structure (see reference). Figure 7 ).

[0178] In this method, film formation using a second raw material gas is performed, and film formation using a first raw material gas is also combined. The first SiO film, which has a higher step coverage than the second SiO film, is formed before the second SiO film. This suppresses the formation of voids and seams within the concave structure (see reference). Figure 8 According to this method, in step B, even when the second SiO film is formed until the entire concave structure is filled by the first SiO film and the second SiO film, the occurrence of voids and seams in the concave structure can be suppressed.

[0179] (g) In step A, by using a gas containing amino groups in its molecular structure as the first raw material gas, the occurrence of voids and seams in the recessed structure can be suppressed.

[0180] This is because, when using a gas containing amino groups in its molecular structure as the raw material gas, compared to using a gas without amino groups in its molecular structure, the surface reaction between the raw material gas molecules and the surface of the wafer 200 can be optimized, thereby improving the step coating properties of the formed film. In this method, the first raw material gas containing amino groups in its molecular structure is supplied before the second raw material gas without amino groups in its molecular structure, and the first SiO film, which has a higher step coating property than the second SiO film, is formed before the second SiO film, thereby suppressing the occurrence of voids, seams, etc. in the recessed structure.

[0181] (h) By making the oxidizing power of the first reaction gas supplied in step A smaller than the oxidizing power of the second reaction gas supplied in step B, oxidation of the surface of the wafer 200, which serves as the substrate, can be suppressed in step A.

[0182] Furthermore, by making the oxidizing power of the second reactant gas supplied in step B greater than that of the first reactant gas supplied in step A, the second SiO film formed in step B can be sufficiently oxidized. Additionally, even if there are areas of insufficient oxidation remaining on the first SiO film formed in step A, the high oxidizing power of the second reactant gas in step B can be used to fully oxidize such areas.

[0183] Thus, in this method, the oxidation of the substrate can be suppressed and the oxidation of the first SiO film and the second SiO film can be reliably achieved simultaneously.

[0184] It should be noted that when only the first reactant gas with low oxidizing power is used as the reactant gas in each step A and B, even if the oxidation of the substrate can be suppressed, the oxidation of the first SiO film and the second SiO film may not be sufficient. Furthermore, when only the second reactant gas with high oxidizing power is used as the reactant gas in each step A and B, even if the first SiO film and the second SiO film are sufficiently oxidized, the oxidation of the substrate may not be suppressed.

[0185] (i) By setting the ratio of the thickness of the first SiO film to the total thickness of the first SiO film and the second SiO film (the thickness of the stacked SiO films) to 10% or more, oxidation of the substrate caused by the second reactive gas supplied in step B can be suppressed. Furthermore, the step coverage of the formed stacked SiO film can be improved. If the ratio of the thickness of the first SiO film to 10% is less than 10%, substrate oxidation may not be suppressed. Additionally, the step coverage of the formed stacked SiO film may decrease.

[0186] (4) Variations

[0187] The substrate processing sequence in this method can be changed as shown in the following variations. Unless otherwise specified, the processing sequence and processing conditions in each step of each variation can be set to be the same as those in each step of the substrate processing sequence described above.

[0188] As described above, step B is performed after step A. Alternatively, it can be done as follows: Figure 5 The order of the steps will be changed as shown below, with step A performed after step B.

[0189] In this modified example, in step B, it is preferable to form a second SiO film until the second SiO films formed on opposite sides of the concave structure disposed on the surface of the wafer 200 are in contact with each other (film thickness). Furthermore, it is more preferable to form a second SiO film until at least a portion of the bottom of the concave structure is embedded by the second SiO film, which has a weaker adhesion than the first SiO film.

[0190] (Second raw material gas → Second reactant gas) × n → (First raw material gas → First reactant gas) × m

[0191] It should be noted that, preferably, before step B, O-containing gas and H-containing gas are supplied (pre-flowed) to the wafer 200 as the second reaction gas, as shown in the gas supply process below. The processing sequence in this step can be set to the same processing sequence as in step b2 above.

[0192] Second reactant gas → (Second feed gas → Second reactant gas) × n → (First feed gas → First reactant gas) × m

[0193] As conditions in this step, examples include:

[0194] Processing pressure: less than atmospheric pressure, preferably 0.1 to 20 Torr, more preferably 0.2 to 0.8 Torr

[0195] O-containing gas supply flow rate: 0.1–10 slm, preferably 0.5–10 slm

[0196] H-containing gas supply flow rate: 0.01–5 slm, preferably 0.1–1.5 slm

[0197] Gas supply time: 1–200 seconds, preferably 15–50 seconds

[0198] Inactive gas supply flow rate (per gas supply pipe): 0-10 slm.

[0199] Other processing conditions can be set to the same conditions as those used during the initial feed gas supply in the OH end-capping formation.

[0200] By performing this step under the above-described processing conditions, hydroxyl capping (OH capping) can be formed over the entire surface area of ​​the wafer 200. The OH capping present on the surface of the wafer 200 functions as adsorption sites for the raw material gas, i.e., adsorption sites for the molecules and atoms constituting the raw material gas, in the film formation process described later.

[0201] After forming the OH end cap, valves 243b and 243d are closed to stop the supply of O-containing gas and H-containing gas to the processing chamber 201, respectively. Furthermore, the gas remaining in the processing chamber 201 is removed (purged) using the same processing sequence and conditions as in step a1.

[0202] In step B, it is preferable to set the ratio of the thickness of the second SiO film, relative to the combined thickness of the first SiO film as the first film and the second SiO film as the second film, to 90% or less. By setting this ratio, oxidation of the substrate caused by the second reactive gas supplied in step B can be suppressed. Furthermore, the step coverage of the formed stacked SiO film can be improved. If the ratio of the thickness of the second SiO film is higher than 90%, substrate oxidation may not be suppressed. Additionally, there is a possibility that the step coverage of the formed stacked SiO film may decrease.

[0203] In step B, it is preferable to set the ratio of the thickness of the second SiO film to the total thickness of the first SiO film (as the first film) and the second SiO film (as the second film) to 50% or more. By setting this ratio, it is possible to prevent the surfaces of the first SiO films formed on the inner surface of the concave structure from contacting each other, thereby suppressing pattern collapse. If the ratio of the thickness of the second SiO film is less than 50%, it is impossible to prevent the surfaces of the first SiO films formed on the inner surface of the concave structure from contacting each other, increasing the likelihood of pattern collapse.

[0204] In this modified example, in step B, the bottom of the concave structure is filled to a certain extent with a second SiO film, which has a weaker adhesion than the first SiO film (serving as the first film), before step A is performed. Therefore, it is possible to suppress the occurrence of pattern collapse starting from the bottom (see reference). Figure 9 ).

[0205] <Other ways of publishing this text>

[0206] The foregoing has provided a detailed description of the manner in which this disclosure is made. However, this disclosure is not limited to the manner described above and is open to various modifications without departing from its spirit.

[0207] In the above-described manner, an example of forming a SiO film (stacked SiO film) on wafer 200 by sequentially performing steps A and B is described. However, this disclosure is not limited to this manner. For example, steps A and B can be performed sequentially, and step A can be performed again after step B to form a SiO film formed by sequentially stacking a first SiO film, a second SiO film, and a third first SiO film on wafer 200. Since step A is performed twice while the concave structure is filled to a certain extent with the first SiO film and the second SiO film, pattern collapse can be suppressed. Furthermore, since the concave structure is filled by two steps of step A based on the first SiO film with excellent step coverage, the occurrence of voids and seams can be suppressed more reliably.

[0208] In the above description, an example of performing steps A and B within the same processing chamber 201 (in-situ) has been illustrated. However, this disclosure is not limited to this method. For example, steps A and B may be performed separately in different processing chambers (ex-situ). In this case, it is preferable that the wafer 200 is not exposed to the atmosphere between steps A and B. In such a case, the same effect as in the above-described method can be obtained.

[0209] In the above description, an example of forming a second SiO film in step B until the entire concave structure is filled has been illustrated. However, this disclosure is not limited to this method. For example, in step B, the second SiO film may also be formed to fill at least a portion of the concave structure. In this case, the same effect as in the above-described method can also be obtained.

[0210] Furthermore, in steps A and B, not only SiO films can be formed, but also silicon-based oxide films such as silicon oxycarbonate (SiOC), silicon oxycarbonitrile (SiOCN), silicon oxynitride (SiON), silicon boron oxynitride (SiBON), and silicon boron oxycarbonitrile (SiBOCN) films can be formed. Additionally, in steps A and B, metallic oxide films such as aluminum oxide (AlO), titanium oxide (TiO), hafnium oxide (HfO), and zirconium oxide (ZrO) films can also be formed.

[0211] In the above-described method, an example of forming a film using a batch substrate processing apparatus that processes multiple substrates at once has been explained. This disclosure is not limited to the above-described method; for example, it can also be suitably applied when forming a film using a monolithic substrate processing apparatus that sequentially processes one or more substrates. Furthermore, in the above-described method, an example of forming a film using a substrate processing apparatus with a hot-wall type furnace has been explained. This disclosure is not limited to the above-described method; it can also be suitably applied when forming a film using a substrate processing apparatus with a cold-wall type furnace.

[0212] When using the substrate processing apparatus described above, each process can be performed in the same order and under the same conditions as described above, and the same effect as described above can be obtained.

[0213] The above methods can be used in appropriate combinations. For example, the processing order and conditions can be set to be the same as those in the methods described above.

[0214] Example

[0215] Using the substrate processing apparatus described above, a wafer with a concave structure on its surface is processed in the manner described above, thereby forming a first SiO film and a second SiO film by embedding them into the concave structure, thus producing sample 1. In producing sample 1, (dimethylamino)trimethoxysilane gas was used as the first raw material gas, O2 gas was used as the first reactant gas, HCDS gas was used as the second raw material gas, and O2 gas + hydrogen (H2) gas was used as the second reactant gas.

[0216] Using the substrate processing apparatus described above, a wafer with the same structure as the wafer used in fabricating Sample 1 is processed in the modified example sequence described above, thereby forming a first SiO film and a second SiO film by embedding them into the concave structure, thus fabricating Sample 2. In fabricating Sample 2, the first raw material gas, the first reactant gas, the second raw material gas, and the second reactant gas are the same gases used in fabricating Sample 1.

[0217] Using the substrate processing apparatus described above, a wafer with the same structure as the wafer used in fabricating Sample 1 is processed only in step A of the above-described processing sequence, thereby forming a first SiO film by embedding it within a concave structure, thus fabricating Sample 3. In fabricating Sample 3, the first raw material gas and the first reactive gas are the same gases used in fabricating Sample 1. Other processing conditions are set to be the same as those in step A of Sample 1.

[0218] Using the substrate processing apparatus described above, a wafer with the same structure as the wafer used in fabricating Sample 1 is processed only in step B of the above-described processing sequence, thereby forming a second SiO film by embedding it within a concave structure, thus fabricating Sample 4. In fabricating Sample 4, the second raw material gas and the second reactive gas are the same gases used in fabricating Sample 1. Other processing conditions are set to be the same as those in step B of Sample 1.

[0219] Furthermore, the study investigated whether pattern collapse occurred in samples 1–4 and whether substrate oxidation could be inhibited.

[0220] Whether pattern collapse occurred was determined by observing cross-sectional TEM images of the SiO film formed on the pattern. Observation of the cross-sectional TEM images confirmed that sample 3, which was supplied with only the first raw material gas (organic gas), experienced more pattern collapse than sample 4, which was supplied with only the second raw material gas (inorganic gas). For samples 3 and 4, histograms were prepared with the distance between adjacent patterns (the distance between the sides at the top of the concave structure formed on the wafer surface) as the horizontal axis and the number of adjacent patterns reaching each distance as the vertical axis. The results showed that sample 3 deviated from sample 4 in terms of the distance between adjacent patterns. Therefore, the standard deviation (nm) of the distance between adjacent patterns was calculated for samples 3 and 4 respectively, and the standard deviation of sample 3 was larger than that of sample 4. Based on this result, the standard deviation of sample 4 was used as a threshold to determine whether pattern collapse occurred. The standard deviation (nm) of the distance between adjacent patterns was calculated for samples 1 and 2 respectively. The results showed that the standard deviation of samples 1 and 2 was smaller than that of sample 4. Therefore, it was determined that no pattern collapse occurred in samples 1 and 2.

[0221] To determine whether substrate oxidation could be suppressed, cross-sectional TEM images of the SiO films formed on the patterns of samples 1-4 were observed, and the thickness (nm) of the oxide film on the wafer surface serving as the substrate was measured as the amount of substrate oxidation. The thickness of the oxide film on the wafer surface of samples 1-4 was measured, and the results showed that the oxide film thickness of sample 1 was 1.2 nm, sample 2 was 1.4 nm, sample 3 was 0.6 nm, and sample 4 was 1.5 nm. Based on these results, the ability to suppress substrate oxidation was determined using the oxide film thickness of sample 4 (1.5 nm) as a threshold. The results showed that the oxide film thicknesses of samples 1 and 2 were thinner than that of sample 4, therefore, it was determined that substrate oxidation was suppressed in samples 1 and 2.

[0222] Explanation of reference numerals in the attached figures

[0223] 200 chips

[0224] 201 Processing Room

Claims

1. A substrate processing method, which has the following characteristics: (a) A process of forming a first film with a predetermined adhesion on the inner surface of the concave structure by repeatedly performing a process of supplying a first raw material gas and a process of supplying a first oxidizing gas to a substrate having a concave structure on its surface a predetermined number of times, wherein the first film is an oxide film; and (b) A process of forming a second film with a weaker adhesion than the first film on the first film by repeatedly performing a process of supplying a second raw material gas to the substrate at different times and a process of supplying a second oxidizing gas with a stronger oxidizing power than the first oxidizing gas a predetermined number of times, wherein the second film is an oxide film.

2. The substrate processing method according to claim 1, wherein, The inner surface of the concave structure has opposing side surfaces and a bottom surface. In (a), the first film is formed while maintaining a state in which the first films formed on the opposite sides do not contact each other. In (b), the second membrane is formed until at least a portion of the opposing second membranes come into contact with each other.

3. The substrate processing method according to claim 1, wherein, The first membrane has a higher step coverage than the second membrane.

4. The substrate processing method according to claim 1, wherein, The molecular weight of the first raw material gas is greater than that of the second raw material gas.

5. The substrate processing method according to claim 4, wherein, The first raw material gas is an organic gas. The second raw material gas is an inorganic gas.

6. The substrate processing method according to claim 1, wherein, In (b), the second membrane is formed until at least a portion of the concave structure is filled by the first membrane and the second membrane.

7. The substrate processing method according to claim 6, wherein, In (b), the second membrane is formed until the entire concave structure is filled by the first membrane and the second membrane.

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

9. The substrate processing method according to claim 1, wherein, The first raw material gas and the second raw material gas each have a molecular structure containing specified elements. The first membrane and the second membrane are membranes containing the specified elements.

10. The substrate processing method according to claim 9, wherein, The specified element is silicon. An amino group is bonded to one of the silicon atoms in the first raw material gas, and an alkoxy group is bonded to the remaining three bonds.

11. The substrate processing method according to claim 10, wherein, In (a), the first raw material gas is supplied to the substrate under the condition that the alkoxy group is not removed from the silicon but the amino group is removed from the silicon, and the amino group is removed and the silicon is maintained in a state of being bonded to the alkoxy group, and the silicon is adsorbed onto the surface of the substrate.

12. The substrate processing method according to claim 10, wherein, The first raw material gas is dialkylaminotrialkoxysilane gas.

13. The substrate processing method according to any one of claims 9 to 12, wherein, The second raw material gas has a molecular structure containing halogen elements bonded to the specified element.

14. The substrate processing method according to claim 1, wherein, Following (b), (a) is performed to form the first membrane on the second membrane.

15. The substrate processing method according to claim 1, wherein, Before (a), the first oxidizing gas is further supplied.

16. The substrate processing method according to claim 15, wherein, Hydroxyl end caps are formed over the entire surface area of ​​the substrate.

17. A method for manufacturing a semiconductor device, comprising: (a) A process of forming a first film with a predetermined adhesion on the inner surface of the concave structure by repeatedly performing a process of supplying a first raw material gas and a process of supplying a first oxidizing gas to a substrate having a concave structure on its surface a predetermined number of times, wherein the first film is an oxide film; and (b) A process of forming a second film with a weaker adhesion than the first film on the first film by repeatedly performing a process of supplying a second raw material gas to the substrate at different times and a process of supplying a second oxidizing gas with a stronger oxidizing power than the first oxidizing gas a predetermined number of times, wherein the second film is an oxide film.

18. A substrate processing apparatus, comprising: A first raw material gas supply system supplies a first raw material gas to the substrate; A second raw material gas supply system supplies a second raw material gas with a molecular structure different from that of the first raw material gas to the substrate. A first oxidizing gas supply system supplies a first oxidizing gas to the substrate; A second oxidizing gas supply system supplies the substrate with a second oxidizing gas that has a greater oxidizing power than the first oxidizing gas; and The control unit is configured to control the first raw material gas supply system, the second raw material gas supply system, the first oxidizing gas supply system, and the second oxidizing gas supply system to perform the following: (a) A process of forming a first film with a predetermined adhesion on the inner surface of the concave structure by repeatedly performing a process of supplying the first raw material gas and a process of supplying the first oxidizing gas to the substrate having a concave structure on its surface a predetermined number of times, wherein the first film is an oxide film; and (b) A process of forming a second film with a weaker adhesion than the first film on the first film by performing a predetermined number of cycles of supplying the second raw material gas and supplying the second oxidizing gas to the substrate at different times, wherein the second film is an oxide film.

19. A computer-readable recording medium having recorded programs that, when executed by a computer, cause a substrate processing apparatus to perform the following (a) and (b): (a) A step of forming a first film with a predetermined adhesion on the inner surface of the concave structure by repeatedly performing a step of supplying a first raw material gas and a step of supplying a first oxidizing gas to a substrate having a concave structure on its surface a predetermined number of times, wherein the first film is an oxide film; and (b) A step of forming a second film with a weaker adhesion than the first film on the first film by repeatedly performing a step of supplying a second raw material gas to the substrate at different times and a step of supplying a second oxidizing gas with a stronger oxidizing power than the first oxidizing gas a predetermined number of times, wherein the second film is an oxide film.

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