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

Abstract

Provided is a method that makes it possible to improve the number (throughput) of substrates etched per unit time while suppressing the residue of a component derived from a reformed gas.　The method comprises an etching step of sequentially starting: (a1) a step of supplying a first reformed gas to a substrate, and forming a first modified layer at a first rate on at least a portion of a surface of a predetermined substance on the substrate; (a2) a step of supplying a second modified gas having a molecular structure different from that of the first modified gas to the substrate, and forming a second modified layer at a second rate that is lower than the first rate in at least a portion of a region including the first modified layer on the surface of the predetermined substance; and (b) a step of supplying a reaction gas that reacts with the second modified layer to the substrate, and removing at least a portion of the second modified layer from the substrate.

Description

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

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

[0002] 2. Description of the Related Art One step in the manufacturing process of a semiconductor device is to etch a predetermined material (for example, a film-like material) by supplying different gases a predetermined number of times (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2021-158142

[0004] The present disclosure provides a technique that can improve the number of substrates etched per unit time (throughput) while suppressing residual components derived from the modifying gas.

[0005] According to one aspect of the present disclosure, there is provided a technology comprising: (a1) a step of supplying a first modifying gas to a substrate and forming a first modified layer at a first rate on at least a portion of a surface of a predetermined material on the substrate; (a2) a step of supplying a second modifying gas having a molecular structure different from that of the first modifying gas to the substrate and forming a second modified layer at a second rate lower than the first rate on at least a portion of an area including the first modified layer on the surface of the predetermined material; and (b) a step of supplying a reactive gas that reacts with the second modified layer to the substrate and removing at least a portion of the second modified layer from the substrate.

[0006] According to the present disclosure, it is possible to improve the number of substrates etched per unit time (throughput) while suppressing the residual components derived from the modifying gas.

[0007] FIG. 1 is a schematic diagram of a vertical processing furnace of a substrate processing apparatus suitable for use in one embodiment of the present disclosure, showing a vertical cross-sectional view of the processing furnace portion. FIG. 2 is a schematic diagram of a controller of a substrate processing apparatus suitable for use in one embodiment of the present disclosure, showing a control system of the controller in a block diagram. FIG. 3 is a diagram illustrating an etching process according to one embodiment of the present disclosure. FIG. 4 is a conceptual diagram illustrating changes in a predetermined substance on a substrate during the etching process according to one embodiment of the present disclosure. FIG. 5(A) is a diagram illustrating a first variation of the etching process according to one embodiment of the present disclosure. FIG. 5(B) is a diagram illustrating a second variation of the etching process according to one embodiment of the present disclosure. FIG. 6 is a diagram illustrating a third variation of the etching process according to one embodiment of the present disclosure. FIG. 7 is a diagram illustrating changes in a predetermined substance on a substrate during variations 3 and 4 of the etching process according to one embodiment of the present disclosure. FIG. 8 is a diagram illustrating a fourth variation of the etching process according to one embodiment of the present disclosure.

[0008] <One Aspect of the Present Disclosure> One aspect of the present disclosure will be described below, mainly with reference to Figures 1 to 4. Note that all drawings used in the following description are schematic, and the dimensional relationships between elements, the ratios of elements, and the like shown in the drawings do not necessarily match those in reality. Furthermore, the dimensional relationships between elements, the ratios of elements, and the like do not necessarily match between multiple drawings.

[0009] (1) Configuration of the Substrate Processing Apparatus As shown in FIG. 1, a processing furnace 202 serving as a substrate processing apparatus has a heater 207 as a heating mechanism (temperature adjustment unit). The heater 207 also functions as an activation mechanism (excitation unit) that thermally activates (excites) gas. A reaction tube 203 is disposed inside the heater 207. A processing chamber 201 capable of accommodating wafers 200 serving as substrates is formed in the cylindrical hollow portion of the reaction tube 203. The wafers 200 are processed in this processing chamber 201. Nozzles 249a to 249c are disposed inside the processing chamber 201 so as to penetrate the lower sidewall of the reaction tube 203. Gas supply pipes 232a to 232c are connected to the nozzles 249a to 249c, respectively.

[0010] The gas supply pipes 232a to 232c are respectively provided, from the upstream side of the gas flow, with mass flow controllers (MFCs) 241a to 241c, which are flow rate control devices (flow rate control parts), and valves 243a to 243c, which are on-off valves. A gas supply pipe 232d is connected to the gas supply pipe 232a downstream of the valve 243a. A gas supply pipe 232e is connected to the gas supply pipe 232b downstream of the valve 243b. A gas supply pipe 232f is connected to the gas supply pipe 232c downstream of the valve 243c. The gas supply pipes 232d to 232f are respectively provided, from the upstream side of the gas flow, with MFCs 241d to 241f and valves 243d to 243f.

[0011] The nozzles 249a to 249c are each provided in a circular space between the inner wall of the reaction tube 203 and the wafers 200 in a plan view, extending from the bottom to the top of the inner wall of the reaction tube 203 and rising upward in the arrangement direction of the wafers 200. Gas supply holes 250a to 250c for supplying gas are provided on the side surfaces of the nozzles 249a to 249c, respectively. The gas supply holes 250a to 250c are each open toward the center of the reaction tube 203, allowing gas to be supplied toward the wafers 200. A plurality of the gas supply holes 250a to 250c are provided from the bottom to the top of the reaction tube 203.

[0012] As described above, in this embodiment, gas is transported (supplied) via the nozzles 249a to 249c into a space defined by the inner wall of the sidewall of the reaction tube 203 and the edges (peripheries) of the plurality of wafers 200 arranged in the reaction tube 203. Then, gas is supplied toward the wafers 200 in the reaction tube 203 from the gas supply holes 250a to 250d opened in the nozzles 249a to 249c, respectively.

[0013] A first modifying gas is supplied from the gas supply pipe 232a into the processing chamber 201 via an MFC 241a, a valve 243a, and a nozzle 249a. A second modifying gas having a molecular structure different from that of the first modifying gas is supplied from the gas supply pipe 232b into the processing chamber 201 via an MFC 241b, a valve 243b, and a nozzle 249b. A reactive gas that reacts with the first modified layer 400 and the second modified layer 500 (described later) is supplied from the gas supply pipe 232c into the processing chamber 201 via an MFC 241c, a valve 243c, and a nozzle 249c. An inert gas is supplied from the gas supply pipes 232d to 232f into the processing chamber 201 via MFCs 241d to 241f, valves 243d to 243f, gas supply pipes 232a to 232c, and nozzles 249a to 249c, respectively. The inert gas acts as a purge gas, a carrier gas, a dilution gas, and the like.

[0014] A first modifying gas supply system that supplies a first modifying gas mainly includes the gas supply pipe 232a, the MFC 241a, and the valve 243a. A second modifying gas supply system that supplies a second modifying gas mainly includes the gas supply pipe 232b, the MFC 241b, and the valve 243b. A reactive gas supply system that supplies a reactive gas mainly includes the gas supply pipe 232c, the MFC 241c, and the valve 243c. An inert gas supply system that supplies an inert gas mainly includes the gas supply pipes 232d to 232f, the MFCs 241d to 241f, and the valves 243d to 243f.

[0015] An exhaust pipe 231 for exhausting gas from the processing chamber 201 is connected to the lower sidewall of the reaction tube 203. A vacuum pump 246 serving as a vacuum exhaust device is connected to the exhaust pipe 231 via a pressure sensor 245 serving as a pressure detector (pressure detection unit) for detecting the pressure in the processing chamber 201 and an APC (Auto Pressure Controller) valve 244 serving as a pressure regulator (pressure adjustment unit). The APC valve 244 can evacuate and stop the evacuation of the processing chamber 201 by opening and closing the valve while the vacuum pump 246 is operating. Furthermore, while the vacuum pump 246 is operating, the pressure in the processing chamber 201 can be adjusted by adjusting the valve opening based on pressure information detected by the pressure sensor 245. An exhaust system is mainly composed of the exhaust pipe 231, the pressure sensor 245, and the APC valve 244. The vacuum pump 246 may be included in the exhaust system.

[0016] A seal cap 219 capable of airtightly closing the lower end opening of the reaction tube 203 is provided below the seal cap 219. A rotation mechanism 267 for rotating a boat 217 (described later) is provided below the seal cap 219. A rotation shaft 255 of the rotation mechanism 267 is connected to the boat 217 through the seal cap 219. The rotation mechanism 267 is configured to rotate the wafers 200 by rotating the boat 217. The seal cap 219 is configured to be raised and lowered vertically by a boat elevator 115 serving as an elevating mechanism. The boat elevator 115 is configured as a transfer device (transfer mechanism) that raises and lowers the seal cap 219 to load and unload (transfer) the wafers 200 into and out of the processing chamber 201.

[0017] The boat 217, which serves as a substrate support, is configured to support a plurality of wafers 200, for example, 25 to 200 wafers, in multiple stages in a horizontal position. Heat insulating plates 218 are supported in multiple stages in a horizontal position below the boat 217. Note that in this disclosure, when a numerical range such as "25 to 200 wafers" is expressed, it means that the lower limit and upper limit are included in the range. Therefore, "25 to 200 wafers" means "25 or more and 200 or less." The same applies to other numerical ranges.

[0018] A temperature sensor 263 serving as a temperature detector is installed inside the reaction tube 203. The output of the heater 207 is adjusted based on the temperature information detected by the temperature sensor 263, so that the temperature distribution inside the processing chamber 201 is set to a desired value.

[0019] As shown in FIG. 2 , the controller 121, which serves as a control unit, is configured as a computer including a CPU (Central Processing Unit) 121a, a RAM (Random Access Memory) 121b, a storage device 121c, and an I / O port 121d. The RAM 121b, the storage device 121c, and the I / O port 121d are configured to 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. An external storage device 123 can also be connected to the controller 121. The substrate processing apparatus may include one or more control units. That is, control for performing the substrate processing steps described below may be performed using one control unit or multiple control units. When the term "control unit" is used in this specification, it may include not only one control unit but also multiple control units.

[0020] The storage device 121c is composed of, for example, a flash memory, an HDD (Hard Disk Drive), etc. The storage device 121c readably stores a control program for controlling the operation of the substrate processing apparatus, a process recipe describing the procedures and conditions of the etching process described below, and the like. The process recipe is a combination of procedures in the etching process (etching process) described below that are executed by the controller 121 to obtain a predetermined result, and functions as a program (or program product). Hereinafter, the process recipe, the control program, etc. are collectively referred to simply as a program (or program product). The process recipe is also simply referred to as a recipe. In this specification, the term "program" may refer to a recipe alone, a control program alone, or both. The RAM 121b is configured as a memory area (work area) in which programs, data, etc. read by the CPU 121a are temporarily stored.

[0021] The I / O port 121d is connected to the above-mentioned MFCs 241a to 241f, valves 243a to 243f, pressure sensor 245, APC valve 244, vacuum pump 246, temperature sensor 263, heater 207, rotation mechanism 267, boat elevator 115, and the like.

[0022] The CPU 121a is configured to read and execute a control program from the storage device 121c, and to read a recipe from the storage device 121c in response to input of an operation command from the input / output device 122. The CPU 121a is configured to be able to control, in accordance with the contents of the read recipe, the flow rate adjustment operation of various gases by the MFCs 241a to 241f, the opening and closing operation of the valves 243a to 243f, the opening and closing operation of the APC valve 244 and the pressure adjustment operation by the APC valve 244 based on the pressure sensor 245, the start and stop of the vacuum pump 246, the temperature adjustment operation of the heater 207 based on the temperature sensor 263, the rotation and rotation speed adjustment operation of the boat 217 by the rotation mechanism 267, the lifting and lowering operation of the boat 217 by the boat elevator 115, and the like.

[0023] The controller 121 can be configured by installing the above-mentioned program stored in the external storage device 123 into a computer. The external storage device 123 includes, for example, a magnetic disk such as an HDD, an optical disk such as a CD, a magneto-optical disk such as an MO, and a semiconductor memory such as a USB memory. The storage device 121c and the external storage device 123 are configured as computer-readable recording media on which the program is recorded. Hereinafter, these will be collectively referred to as recording media. When the term recording media is used in this specification, it may include only the storage device 121c alone, only the external storage device 123 alone, or both. Note that the program may be provided to the computer using a communication means such as the Internet or a dedicated line, without using the external storage device 123.

[0024] (2) Substrate Processing Step An example of etching at least a part of the predetermined material 300 formed on the surface of the wafer 200 using the above-described processing furnace 202 as one step in the manufacturing process of a semiconductor device will be described with reference to Figures 3 and 4. In the following description, the operation of each part constituting the processing furnace 202 is configured to be controllable by the controller 121.

[0025] The term "wafer" used in this specification may refer to the wafer itself or to a laminate of the wafer and a predetermined layer or film formed on its surface. The term "surface of a wafer" used in this specification may refer to the surface of the wafer itself or to the surface of a predetermined layer or the like formed on the wafer. When described in this specification, "forming a predetermined layer on a wafer" may mean forming a predetermined layer directly on the surface of the wafer itself or forming a predetermined layer on a layer or the like formed on the wafer. When used in this specification, the term "substrate" is synonymous with the term "wafer".

[0026] (Wafer Charging and Boat Loading) A plurality of wafers 200 formed with a predetermined material 300 to be etched are loaded (wafer charging) into the boat 217. Thereafter, the boat 217 supporting the plurality of wafers 200 is lifted by the boat elevator 115 and carried into the processing chamber 201 (boat loading).

[0027] (Pressure Adjustment and Temperature Adjustment) The inside of the processing chamber 201, i.e., the space in which the wafers 200 are present, is evacuated (reduced pressure exhausted) by the vacuum pump 246 so as to reach a desired processing pressure (vacuum level). The wafers 200 in the processing chamber 201 are also heated by the heater 207 so as to reach a desired processing temperature. Rotation of the wafers 200 by the rotation mechanism 267 is also started. Operation of the vacuum pump 246 and heating and rotation of the wafers 200 are all continued at least until processing of the wafers 200 is completed.

[0028] In this specification, the processing temperature refers to the temperature of the wafer 200 or the temperature inside the processing chamber 201, and the processing pressure refers to the pressure inside the processing chamber 201. Furthermore, the processing time refers to the time the processing continues. These terms also apply to the following explanations.

[0029] Thereafter, the wafer 200 on which the predetermined material 300 to be etched is formed is subjected to the following steps S11 to S16.

[0030] The predetermined material 300 to be etched may be, for example, a metal-containing material such as a metal oxide material. Examples of metal elements contained in the metal oxide material include aluminum (Al), zirconium (Zr), hafnium (Hf), titanium (Ti), yttrium (Y), lanthanum (La), tantalum (Ta), niobium (Nb), ruthenium (Ru), vanadium (V), zinc (Zn), manganese (Mn), cobalt (Co), indium (In), and gallium (Ga).

[0031] Metal oxide materials tend to have a low etching rate. According to the technology of the present disclosure, a modified layer can be formed at a high modification rate even on metal oxide materials. As a result, the etching rate can be improved. In the following description, the thickness of the modified layer formed per unit time is referred to as the "modification rate." Furthermore, the thickness of the modified layer removed per unit time is referred to as the "etching rate."

[0032] Examples of metal oxide materials include metal oxide films. The metal oxide film may contain two or more of these metal elements. In particular, aluminum oxide (Al ２ O ３ ) film, zirconium oxide (ZrO ２ ) film, hafnium oxide (HfO ２ ) film, titanium oxide (TiO ２ ) film, lanthanum oxide (La ２ O ３ ) film, tantalum oxide (Ta ２ O ５ The technique of the present disclosure can be suitably applied to etching high dielectric constant films (high-k films) such as SiO 2 films.

[0033] In the following, the etching target material 300 will be described as a polycrystalline material composed of a large number of crystal grains. In polycrystalline materials, gaps tend to form between the crystal grains. In such cases, the modification rate tends to vary greatly depending on the type of modifying gas.

[0034] If a modified layer is formed using only a modifying gas with a high modification rate, the modified layer can be formed in a short time. However, the modified layer tends to be formed to a depth where it becomes difficult to remove the modified layer by supplying a reactive gas. Therefore, components derived from the modifying gas tend to remain in the film.

[0035] On the other hand, when a modified layer is formed using only a modifying gas with a low modification rate, it takes longer to form the modified layer than when a modifying gas with a high modification rate is used. However, it is difficult to form the modified layer to a depth where removal of the modified layer by supplying a reactive gas becomes difficult. Therefore, components derived from the modifying gas are less likely to remain in the film.

[0036] In the technology disclosed herein, a first modified layer 400 is formed by supplying a first modifying gas at a first rate of modification, and then a second modified layer 500 is formed by supplying a second modifying gas at a second rate of modification that is lower than the first rate. This reduces the time required to form the modified layer compared to forming a modified layer of the same thickness using only the second modifying gas. This improves throughput. Furthermore, compared to forming a modified layer of the same thickness using only the first modifying gas, this reduces the formation of a modified layer deep within the predetermined substance 300. This reduces the amount of residual components derived from the modifying gas contained in the film.

[0037] Here, the region where the predetermined substance 300 is reformed by the supply of the first reforming gas is referred to as the first reforming layer 400. Also, the region where the predetermined substance 300 including at least the first reforming layer 400 is reformed by the supply of the second reforming gas is referred to as the second reforming layer 500. Also, one or both of the first reforming gas and the second reforming gas may be referred to as the "reformed gas." Also, one or both of the first reforming layer 400 and the second reforming layer 500 may be referred to as the "reformed layer."

[0038] When forming the modified layer, the modification of the deep portion of the predetermined material 300 may be started before the modification of the surface side of the predetermined material 300 has progressed sufficiently (or before the reaction of the modifying gas on the surface side of the predetermined material 300 has progressed sufficiently). That is, the surface side of the predetermined material 300 and a part of the deep portion of the predetermined material 300 may be modified simultaneously. When forming the modified layer, the modification of the deep portion of the predetermined material 300 may be started after the modification of the surface side of the predetermined material 300 has progressed sufficiently (or after the reaction of the modifying gas on the surface side of the predetermined material 300 has progressed sufficiently). That is, the surface side of the predetermined material 300 and a part of the deep portion of the predetermined material 300 may be modified non-simultaneously.

[0039] (First modifying gas supply, step S11) In this step, a first modifying gas is supplied to the wafers 200 in the processing chamber 201. Specifically, the valve 243a is opened to allow the first modifying gas to flow into the gas supply pipe 232a. The flow rate of the first modifying gas is adjusted by the MFC 241a, and the first modifying gas is supplied into the processing chamber 201 via the nozzle 249a and exhausted from the exhaust pipe 231. At this time, the valves 243d to 243f are opened to allow an inert gas to flow into the gas supply pipes 232d to 232f.

[0040] In this step, the first modifying gas is supplied to a wafer 200 having a predetermined material 300 to be etched formed thereon, as shown in FIG. 4A. Then, as shown in FIG. 4B, a first modified layer 400 having a first thickness T1 is formed at a first rate on at least a portion of the surface of the predetermined material 300 on the wafer 200. Here, for example, the first modified layer 400 is a layer containing a halogen element such as F, which is a component derived from the first modifying gas. In other words, at least a portion of the predetermined material 300 on the wafer 200 is modified into a layer containing a halogen element, which is a component derived from the first modifying gas.

[0041] Here, the "surface of the predetermined material 300" includes the outermost surface of the predetermined material 300 before the modified layer is formed and the region deeper therefrom. Furthermore, the "thickness of the modified layer" refers to the distance from the outermost surface of the modified layer to the edge of the deeper portion of the modified layer. Note that the "modified layer of a predetermined thickness" may include unmodified predetermined material 300 in a portion of the region from the outermost surface of the modified layer to the predetermined thickness.

[0042] In this step, the first modified layer 400 is preferably formed under conditions where the first modified gas is saturated with respect to the supply time of the first modified gas. The supply of the first modified gas is preferably terminated before the first modified layer 400 reaches the first thickness T1, i.e., before the first thickness T1 reaches the saturated first thickness H1, at which the modification caused by the supply of the first modified gas is self-limited (e.g., fluorination no longer progresses). This facilitates the first thickness T1 of the first modified layer 400 to be less than the depth at which removal of the modified layer by the supply of the reactant gas becomes difficult. As a result, the residue of halogen elements such as F, which are components derived from the modifying gas, in the predetermined substance 300 can be suppressed.

[0043] In this step, it is preferable to set the first thickness T1 of the first modified layer 400 to be smaller than the saturated second thickness H2 at which the reforming by supplying the second modifying gas in step S13 described later is self-limited. This makes it easier to set the first thickness T1 of the first modified layer 400 to a depth below which removal of the modified layer by supplying the reactive gas becomes difficult. This also makes it easier to suppress the residue of halogen elements such as F, which are components derived from the modifying gas, in the predetermined substance 300.

[0044] Examples of processing conditions for supplying the first modifying gas in this step include: Processing temperature: 150 to 900°C, preferably 150 to 400°C Processing pressure: 10 to 10,000 Pa, preferably 10 to 7,000 Pa Supply time of each gas: 20 to 1,200 seconds, preferably 20 to 1,000 seconds Processing partial pressure of the first modifying gas: 10 to 5,000 Pa, preferably 10 to 3,500 Pa. The processing temperature is substantially the same in all steps described below.

[0045] In this disclosure, the supply time of a certain gas refers to the time during which the gas is supplied to the wafer 200 or the inside of the processing chamber 201. Furthermore, the processing partial pressure of a certain gas refers to the partial pressure of the gas in the processing chamber 201. These terms also apply to the following description.

[0046] The first modifying gas may be a fluorine (F)-containing gas. ２ ), nitrogen trifluoride (NF ３ ), hydrogen fluoride (HF), carbon tetrafluoride (CF ４ ), tungsten hexafluoride (WF ６ ), chlorine trifluoride (ClF ３ ), sulfur tetrafluoride (SF ４ ), xenon difluoride (XeF ２ ) can be used. One or more of these can be used as the first modifying gas. Halogen elements such as F are easily desorbed from the film. Therefore, halogen elements are less likely to remain in the predetermined material 300 after the etching process.

[0047] The inert gas is nitrogen (N ２ In addition to the inert gas, rare gases such as argon (Ar), helium (He), neon (Ne), and xenon (Xe) can be used. One or more of these can be used as the inert gas.

[0048] The first modified layer 400 formed in this step is a layer containing elements contained in the first modifying gas and elements contained in the predetermined substance 300, such as a layer containing a halogen element. The layer containing a halogen element is, for example, a layer containing a fluoride. For example, when the predetermined substance 300 is Al, ２ O ３ When the first modifying gas is HF gas, an aluminum fluoride layer (AlF layer) is formed as the first modifying layer. The AlF layer may contain O or H.

[0049] (Exhaust, step S12) The valve 243a is closed to stop the supply of the first modifying gas. At this time, the APC valve 244 of the exhaust pipe 231 is left open, and the processing chamber 201 is evacuated to a vacuum by the vacuum pump 246. This removes residual gases, such as unreacted first modifying gas and reaction by-products remaining on the wafer 200 and / or in the processing chamber 201, from the processing chamber 201. At this time, the valves 243d to 243f may be left open to maintain the supply of an inert gas into the processing chamber 201, thereby purging the processing chamber 201. The inert gas acts as a purge gas, enhancing the effect of removing residual gases from above the wafer 200.

[0050] In this step, it is preferable to evacuate and purge the processing chamber 201, which is the space in which the wafer 200 exists. This can reduce the amount of components derived from the modifying gas contained in the predetermined material 300 after the etching process.

[0051] The evacuation conditions in this step are, for example, processing pressure: 10 to 200 Pa, and processing time: 10 to 180 seconds.

[0052] The purging conditions in this step are, for example, a processing pressure of 10 to 7000 Pa and a processing time of 30 to 180 seconds.

[0053] (Second modifying gas supply, step S13) In this step, a second modifying gas is supplied to the wafers 200 in the processing chamber 201. Specifically, the valve 243b is opened to allow the second modifying gas to flow into the gas supply pipe 232b. The flow rate of the second modifying gas is adjusted by the MFC 241b, and the second modifying gas is supplied into the processing chamber 201 via the nozzle 249b and exhausted from the exhaust pipe 231. At this time, the valves 243d to 243f are opened to allow an inert gas to flow into the gas supply pipes 232d to 232f.

[0054] In this step, the second modifying gas is supplied to the wafer 200, on which a first modified layer 400 has been formed on at least a portion of the surface of the predetermined material 300, as shown in FIG. 4B. Then, as shown in FIG. 4C, a second modified layer 500 is formed at a second rate lower than the first rate in a region of the surface of the predetermined material 300 on the wafer 200 that includes at least the first modified layer 400. That is, the second modified layer 500 is formed in at least a portion of the region where the first modified layer 400 was formed. That is, the second modified layer 500 includes not only a region where the predetermined material 300 has been modified by the second modifying gas, but also a region where the first modified layer 400 has been modified by the second modifying gas. Furthermore, a portion of the second modified layer 500 may include unmodified predetermined material 300 or the first modified layer 400.

[0055] By supplying the second modifying gas to the region where the first modified layer 400 of the predetermined material 300 has been formed in this manner, the time required to form the second modified layer 500 of the same thickness is reduced compared to when the second modifying gas is supplied to the region where the first modified layer 400 of the predetermined material 300 has not been formed, thereby improving the throughput in the etching process.

[0056] That is, in this step, the second thickness T2 of the second modified layer 500 formed in this step is made larger than the first thickness T1 of the first modified layer 400 formed in step S11. This makes it difficult for the modified layer to be formed to a depth at which removal of the modified layer by supplying a reactive gas becomes difficult.

[0057] In this step, the second modified layer 500 is preferably formed under conditions in which the second thickness T2 of the second modified layer 500 is saturated with respect to the supply time of the second modifying gas. The supply of the second modifying gas is preferably terminated when the second thickness T2 is saturated, i.e., when the second thickness T2 reaches the second saturated thickness H2 at which the modification by the supply of the second modifying gas is self-limited. Thus, by saturating the second modified layer 500 to the second saturated thickness H2 of the second modified layer 500 rather than the first saturated thickness H1 of the first modified layer 400 in the above-described step S11, the thickness of the modified layer can be easily controlled below a depth at which removal of the modified layer by the supply of the reactive gas becomes difficult. Furthermore, saturating the second thickness T2 facilitates precise control of the thickness of the modified layer, thereby facilitating control of the thickness of the predetermined material 300 removed in one etching step.

[0058] In this step, it is preferable to set the third thickness T3, which is the thickness of the second modified layer 500 formed in the region where the first modified layer 400 is not formed, to be equal to or less than the first thickness T1 of the first modified layer 400 formed in step S11. The reforming in the region of the third thickness T3 by supplying the second reforming gas in this step has a lower reforming rate than the reforming in the region of the first thickness T1 by supplying the second reforming gas. Therefore, by setting the third thickness T3 to be equal to or less than the first thickness T1, the time required to form the second modified layer 500 can be further shortened.

[0059] Examples of processing conditions for supplying the second modifying gas in this step include: processing temperature: 150 to 900°C, preferably 150 to 400°C processing pressure: 10 to 10,000 Pa, preferably 10 to 7,000 Pa supply time for each gas: 20 to 1,200 seconds, preferably 20 to 1,000 seconds processing partial pressure of the second modifying gas: 10 to 5,000 Pa, preferably 10 to 3,500 Pa.

[0060] The second modifying gas may be an F-containing gas having a molecular structure different from that of the first modifying gas. For example, among the gases exemplified as the first modifying gas, an F-containing gas having a molecular structure different from that of the first modifying gas may be used as the second modifying gas. Halogen elements such as F are easily desorbed from the film. Therefore, halogen elements are less likely to remain in the predetermined material 300 after the etching process.

[0061] It is also preferable to use a gas having a larger molecular size than the first modifying gas as the second modifying gas. This makes it easier to form the second modified layer 500 at a second rate lower than the first rate. For example, when HF gas is used as the first modifying gas, NF 3, which has a larger molecular size than HF gas, is used as the second modifying gas. ３ Gas, etc. can be used. This will be explained below.

[0062] When the predetermined material 300 is a polycrystalline material, gaps with low aspect ratios and gaps with high aspect ratios may exist in the predetermined material 300. Here, a gap with a high aspect ratio means that the opening of the gap is relatively narrow and / or the gap is relatively deep.

[0063] The first modifying gas, which has a small molecular size, can easily reach deep gaps with a high aspect ratio. Therefore, the first modifying gas has a higher modifying rate than the second modifying gas, a shorter time until saturation occurs (the self-limit), and is more likely to form a modified layer in deeper areas where removal of the modified layer by supplying a reactive gas is more difficult. Therefore, when etching is performed using the first modifying gas and the reactive gas, halogen elements such as F, which are components derived from the modifying gas, are more likely to remain in the specified material 300 than when the second modifying gas is used.

[0064] In contrast, the second modifying gas, which has a larger molecular size than the first modifying gas, is less likely to reach deep into gaps with a high aspect ratio. Therefore, the second modifying gas has a lower modifying rate than the first modifying gas, takes a longer time to reach saturation, which causes self-limiting, and is less likely to form a modified layer in the deeper portion where removal of the modified layer by supplying a reactive gas is more difficult. Therefore, when etching is performed using the second modifying gas and the reactive gas, halogen elements such as F, which are components derived from the modifying gas, are less likely to remain in the specified material 300 than when the first modifying gas is used.

[0065] According to the technology of the present disclosure, the first modifying gas having a small molecular size is supplied first, followed by the second modifying gas having a large molecular size. This improves the modifying rate while making it difficult for the modifying by the first and second modifying gases to progress deep into the predetermined substance 300. As a result, it is possible to suppress the residue of halogen elements such as F, which are components derived from the modifying gas, in the predetermined substance 300.

[0066] The second modified layer 500 formed in this step is a layer containing elements contained in the second modifying gas and elements contained in the predetermined substance 300, for example, a layer containing a halogen element. The second modified layer 500 may also contain elements contained in the first modifying gas. The layer containing a halogen element is, for example, a layer containing a fluoride. For example, when the predetermined substance 300 is Al, ２ O ３ The first reforming gas is HF gas and the second reforming gas is NF ３ When the etching gas is used, an AlF layer is formed as the second modified layer 500. The AlF layer may contain O or H. Halogen elements such as F are easily desorbed from the film. Therefore, halogen elements are less likely to remain in the predetermined substance 300 after the etching process.

[0067] (Exhaust, Step S14) The valve 243b is closed to stop the supply of the second modifying gas. Then, the processing chamber 201 is evacuated and / or purged using the same procedure and conditions as in Step S12. This removes residual gases, such as unreacted second modifying gas and reaction by-products remaining on the wafer 200 and / or in the processing chamber 201, from the processing chamber 201.

[0068] (Reactive gas supply, step S15) Next, a reactive gas is supplied to the wafers 200 in the processing chamber 201. Specifically, the valve 243c is opened to allow the reactive gas to flow into the gas supply pipe 232c. The flow rate of the reactive gas is adjusted by the MFC 241c, and the reactive gas is supplied into the processing chamber 201 via the nozzle 249c and exhausted from the exhaust pipe 231. At this time, the valves 243d to 243f are opened to allow the inert gas to flow into the gas supply pipes 232d to 232f.

[0069] In this step, a reaction gas that reacts with the second modified layer 500 is supplied to the wafer 200 on which the second modified layer 500 has been formed on the surface of the predetermined material 300, as shown in FIG. 4C. In this way, as shown in FIG. 4D, at least a portion of the second modified layer 500 on the surface of the predetermined material 300 on the wafer 200 is removed. In other words, in this step, at least a portion of the predetermined material 300 on the wafer 200 can be removed. At this time, it is not necessary that a portion of the second modified layer 500 is removed from the wafer 200.

[0070] Examples of processing conditions for supplying the reactive gas in this step include: processing pressure: 10 to 7000 Pa, preferably 10 to 3000 Pa; supply time of each gas: 20 to 1200 seconds, preferably 20 to 1000 seconds; and processing partial pressure of the reactive gas: 10 to 4000 Pa, preferably 10 to 1500 Pa.

[0071] The reactive gas may be, for example, chlorine (Cl ２ ) gas or a Cl-containing gas containing a predetermined element and chlorine (Cl) can be used. The predetermined element can be, for example, one or more of boron (B), carbon (C), sulfur (S), phosphorus (P), titanium (Ti), silicon (Si), aluminum (Al), tin (Sn), etc. Examples of gases containing these predetermined elements and Cl include boron trichloride (BCl ３ ), carbon tetrachloride (CCl ４ ), thionyl chloride (SOCl ２ ), sulfuryl chloride (SO ２ Cl ２ ), phosgene (COCl ２ ), phosphorus trichloride (PCl３ ), phosphorus pentachloride (PCl ５ ), titanium tetrachloride (TiCl ４ ), silicon tetrachloride (SiCl ４ ), chlorodimethylaluminum (C ２ H ６ AlCl), etc. can be used.

[0072] (Exhaust, Step S16) The valve 243c is closed to stop the supply of the reaction gas. Then, the process chamber 201 is evacuated and / or purged using the same procedures and conditions as in Steps S12 and S14. This removes residual gases, such as unreacted reaction gases and reaction by-products remaining on the wafer 200 and / or in the process chamber 201, from the process chamber 201.

[0073] By performing the above-described steps S11 to S16 in this order, at least a portion of the predetermined material 300 on the wafer 200 can be removed (also called etching).

[0074] (After-purging and atmospheric pressure return) An inert gas is supplied into the processing chamber 201 from each of the gas supply pipes 232d to 232f and exhausted through the exhaust pipe 231. This purges the processing chamber 201, and gases and reaction by-products remaining in the processing chamber 201 are removed from the processing chamber 201 (after-purging). Thereafter, the atmosphere in the processing chamber 201 is replaced with the inert gas (inert gas replacement), and the pressure in the processing chamber 201 is returned to normal pressure (atmospheric pressure return).

[0075] (Boat Unloading and Wafer Discharge) Thereafter, the seal cap 219 is lowered by the boat elevator 115, and the bottom end of the reaction tube 203 is opened. Then, the processed wafers 200, supported by the boat 217, are unloaded from the bottom end of the reaction tube 203 to the outside of the reaction tube 203 (boat unloading). The processed wafers 200 are removed from the boat 217 (wafer discharge).

[0076] In the above-described steps S11, S13, and S15, the first modifying gas, the second modifying gas, and the reactive gas are not activated using plasma. According to the technology of the present disclosure, the time required for forming a modified layer can be shortened without using plasma. Therefore, the etching rate can be improved while suppressing alteration of the predetermined substance 300 formed on the wafer 200 by plasma. In one or more of the above-described steps S11, S13, and S15, the first modifying gas, the second modifying gas, and the reactive gas may be activated by plasma. Even in this case, at least some of the effects of the present disclosure can be obtained.

[0077] Other Aspects of the Present Disclosure The above describes specific aspects of the present disclosure. However, the present disclosure is not limited to the above aspects and can be modified in various ways without departing from the spirit and scope of the present disclosure.

[0078] (Variation 1) Figure 5(A) shows the flow of Variation 1 of the etching process of the present disclosure. In this variation, the above-described steps S11 to S16 are started in this order, but the timing of starting the supply of the second modifying gas in step S13 differs from the above-described embodiment. That is, step S12 is omitted, and the supply of the second modifying gas is started before the supply of the first modifying gas is finished. Then, the supply of the second modifying gas is finished after the supply of the first modifying gas is finished. This variation also achieves the same effects as the above-described embodiment. Furthermore, in this variation, the time required to form the modified layer is further shortened, thereby improving the throughput of the etching process.

[0079] (Variation 2) Figure 5(B) shows a flow of Variation 2 of the etching process of the present disclosure. In this variation, the above-described steps S11 to S16 are started in this order, but the timing of starting the supply of the second modifying gas in step S13 differs from the above-described embodiment. That is, step S12 is omitted, and the supply of the second modifying gas is started simultaneously with the end of the supply of the first modifying gas. This variation also achieves the same effects as the above-described embodiment. Furthermore, in this variation, the time required to form the modified layer is further shortened, thereby improving the throughput of the etching process.

[0080] (Variation 3) Figure 6 shows a flow chart of Variation 3. In the etching process of this variation, a first etching process is performed in which the cycle of steps S11 to S16 described above is performed a first number of times (n times, where n is an integer of 1 or 2 or more) in sequence, followed by a second etching process in which the cycle of steps S11 to S16 described above is performed a second number of times (m times, where m is an integer of 1 or 2 or more). Here, the supply time of the first modifying gas in step S11 of the first etching process is a first time, and the supply time of the first modifying gas in step S11 of the second etching process is a second time that is shorter than the first time. In this variation, the same effects as those of the above-described embodiment can be obtained.

[0081] That is, in the second etching step, the supply time of the first modifying gas, which has a higher modification rate, is set shorter than the supply time of the first modifying gas in the first etching step. In this case, the first modified layer can be made thicker in the first etching step than in the second etching step, making it easier to form the second modified layer. This improves throughput. Furthermore, in the second etching step, the first modified layer can be made thinner than in the first etching step, making it difficult for the modified layer to be formed to a depth at which removal of the modified layer by the supply of the reactive gas would be difficult. This reduces the likelihood of components derived from the modifying gas remaining in the specified substance 300 after the etching step is completed.

[0082] A more preferred embodiment of Modification 3 will be described below with reference to Figure 7. Figure 7(A) is an image of wafer 200 on which predetermined material 300 to be etched is formed. Figure 7(B) is an image of predetermined material 300 on wafer 200 after completion of the first etching step. Figure 7(C) is an image of predetermined material 300 on wafer 200 after completion of the second etching step.

[0083] In the first etching step, it is preferable to make the thickness T2 of the second modified layer 500 formed in the first etching step smaller than the thickness T1 of the first modified layer 400 formed in the first etching step. In this case, the entire second modified layer 500 can be formed within the first modified layer 400, further shortening the time required to form the modified layer in the first etching step. However, in this case, as shown in FIG. 7B, the first modified layer 400 with a thickness TX will be present on the surface of the predetermined material 300 at the end of the first etching step.

[0084] In such a case, in the second etching step, it is preferable to make the thickness T4 of the second modified layer 500 formed in the second etching step greater than the thickness T3 of the first modified layer 400 formed in the second etching step. This reduces the influence of components derived from the first modifying gas remaining in the predetermined substance 300 in the first etching step. That is, it is possible to further reduce impurities in the predetermined substance 300 after completion of the etching step while further improving throughput. Note that, for example, the thickness T3 of the first modified layer 400 and the thickness T4 of the second modified layer 500 formed in the second etching step can be increased by increasing the supply times of the first modifying gas and the second modifying gas in the second etching step.

[0085] In such a case, it is preferable that the second etching step removes at least the predetermined material 300 in a region deeper than the deepest part of the first modified layer 400 having a thickness TX. In other words, it is preferable that the second etching step removes the predetermined material 300 from the wafer 200 in a region deeper than the deepest part of the first modified layer 400 that is present on the surface of the predetermined material 300 at the end of the first etching step. This improves throughput and further reduces impurities in the predetermined material 300 after the etching step is completed.

[0086] 8 shows a flow chart of Modification 4. In the etching process of this modification, a third etching process is performed in which the cycle of steps S11 to S16 described above is performed a third number of times (p times, where p is an integer of 1 or 2 or more) in order, followed by a fourth etching process in which the cycle of steps S13 to S16 described above is performed a fourth number of times (q times, where q is an integer of 1 or 2 or more) in order. This modification also provides the same effects as the above-described embodiment.

[0087] In other words, the fourth etching step does not include the supply of the first modifying gas, which has a high modification rate. In this case, the first modified layer can be made thicker in the third etching step than in the fourth etching step, which facilitates the formation of the second modified layer. This improves throughput. Furthermore, since the first modifying gas is not supplied in the fourth etching step, at least a portion of the first modified layer formed by the supply of the first modifying gas in the third etching step can be removed in the fourth etching step. This reduces the likelihood of components derived from the modifying gas remaining in the predetermined substance 300 after the etching step is completed.

[0088] A more preferred embodiment of Modification 4 will be described below with reference to FIG. 7. In the third etching step, it is preferable to make the thickness T2 of the second modified layer 500 formed in the third etching step smaller than the thickness T1 of the first modified layer 400 formed in the third etching step. In this case, the entire second modified layer 500 can be formed within the first modified layer 400, further shortening the time required to form the modified layer in the third etching step. However, in this case, as shown in FIG. 7B, the first modified layer 400 with a thickness TX will be present on the surface of the predetermined material 300 at the end of the third etching step.

[0089] In such a case, it is preferable that the fourth etching step removes at least the predetermined material 300 in a region deeper than the deepest part of the first modified layer 400 having a thickness TX. In other words, it is preferable that the fourth etching step removes the predetermined material 300 from the wafer 200 in a region deeper than the deepest part of the first modified layer 400 that is present on the surface of the predetermined material 300 at the end of the third etching step. This improves throughput and further reduces impurities in the predetermined material 300 after the etching step is completed.

[0090] In Modifications 3 and 4, the thickness T1 of the first modified layer 400 formed in the first etching step and the third etching step may be saturated. In this case, the time required to form the second modified layer 500 in the first etching step and the third etching step can be further shortened. Furthermore, in Modifications 3 and 4, the thickness T1 of the first modified layer 400 formed in the first etching step and the third etching step does not have to be saturated. In this case, the first modified layer 400 present on the surface of the predetermined material 300 at the end of the first etching step and the third etching step can be thinned. Therefore, even when the etching amount in the second etching step is set small, impurities in the predetermined material 300 after the etching step is completed can be reduced.

[0091] In Modifications 3 and 4, the thickness T2 of the second modified layer 500 formed in the first etching step and the third etching step may be greater than the thickness T1 of the first modified layer 400 formed in the first etching step. In this case, at least some of the above-described effects can be obtained.

[0092] (Other Aspects) In the above aspect, a process for etching a film formed on the wafer 200 has been described as an example. However, the present disclosure is not limited to this. For example, the technology of the present disclosure can be suitably applied to a process for etching a film formed on the surface of the inner wall of the processing chamber 201, the boat 217, or the like (a cleaning process inside the processing chamber 201). Furthermore, for example, the technology of the present disclosure can be suitably applied to a case where a process for forming a film on the wafer 200 is performed inside the processing chamber 201 and the film is etched inside the processing chamber 201. In these aspects as well, the same effects as those of the above aspect can be obtained.

[0093] The predetermined material 300 to be etched may be a material other than a metal oxide material. For example, the predetermined material 300 may be a metal film. For example, the metal film may be a film substantially composed of metal elements such as cobalt (Co), copper (Cu), iron (Fe), molybdenum (Mo), nickel (Ni), or tungsten (W). Alternatively, the predetermined material 300 may be a semiconductor film. For example, the semiconductor film may be a film substantially composed of semiconductor elements such as silicon (Si) or germanium (Ge). Alternatively, the predetermined material 300 may be an indium-gallium-arsenic (InGaAs) film, an indium-aluminum-arsenic (InAlAs) film, an indium-gallium-zirconium-oxygen (InGaZrO ４ The film may be a silicon nitride (SiN) film, a titanium nitride (TiN) film, etc. In these cases, at least some of the above-mentioned effects can be obtained.

[0094] The first and second modifying gases may be gases other than F-containing gases. For example, the first and second modifying gases may be Cl-containing gases, oxidizing gases, or organic ligand-containing gases. For example, the oxidizing gas may be oxygen (O ２ ), ozone (O ３ ), water vapor (H ２ O), hydrogen (H ２ ) and O ２The organic ligand-containing gas may be a mixture of trimethylaluminum gas, acetylacetone (Hacac) gas, dimethylacetamide gas, tin (II) acetylacetonate (Sn(acac) ２ ) gas, hexafluoroacetylacetone (Hhfac) gas, etc. can be used. The reactive gas may be a gas other than a Cl-containing gas. For example, the reactive gas may be the above-mentioned F-containing gas, oxidizing gas, or organic ligand-containing gas. The first modifying gas, second modifying gas, and reactive gas can be selected from the above-mentioned gases according to the predetermined material 300 to be etched. Even in this case, at least some of the above-mentioned effects can be obtained.

[0095] It is preferable that recipes used for substrate processing are individually prepared according to the processing content and stored in the storage device 121c via an electric communication line or the external storage device 123. When starting substrate processing, the CPU 121a preferably selects an appropriate recipe from the multiple recipes stored in the storage device 121c according to the processing content. This enables the substrate processing device to process films of various film types, composition ratios, film qualities, and film thicknesses with good reproducibility. This also reduces the burden on the operator, avoids operational errors, and allows substrate processing to be started quickly.

[0096] The above-mentioned recipes may not necessarily be newly created, but may be prepared by modifying an existing recipe already installed in the substrate processing apparatus. When modifying a recipe, the modified recipe may be installed in the substrate processing apparatus via an electric communication line or a recording medium on which the modified recipe is recorded. Alternatively, an existing recipe already installed in the substrate processing apparatus may be directly modified by operating the input / output device 122 provided in the existing substrate processing apparatus.

[0097] In the above-described embodiment, an example has been described in which a batch-type substrate processing apparatus that processes multiple substrates at a time is used. The present disclosure is not limited to the above-described embodiment. For example, the present disclosure can be suitably applied to a case in which a single-wafer type substrate processing apparatus that processes one or several substrates at a time is used. In the above-described embodiment, an example has been described in which a substrate processing apparatus having a hot-wall type processing furnace is used. The present disclosure is not limited to the above-described embodiment. For example, the present disclosure can be suitably applied to a case in which a substrate processing apparatus having a cold-wall type processing furnace is used.

[0098] When using these substrate processing apparatuses, processing can be performed under the same processing procedures and conditions as in the above-described embodiments and modifications, and the same effects as in the above-described embodiments and modifications can be obtained.

[0099] The above-described embodiments and modifications may be used in combination as appropriate. The processing procedures and processing conditions in such a case may be the same as those of the above-described embodiments and modifications, for example.

[0100] 200 Wafer (substrate) 300 Predetermined substance 400 First modified layer 500 Second modified layer

Claims

1. A substrate processing method comprising: (a1) a step of supplying a first modifying gas to a substrate and forming a first modified layer at a first rate on at least a portion of the surface of a predetermined material on the substrate; (a2) a step of supplying a second modifying gas having a molecular structure different from that of the first modifying gas to the substrate and forming a second modified layer at a second rate lower than the first rate on at least a portion of an area of ​​the surface of the predetermined material including the first modified layer; and (b) a step of supplying a reactive gas that reacts with the second modified layer to the substrate and removing at least a portion of the second modified layer from the substrate; and an etching step that starts the above steps in that order.

2. The substrate processing method according to claim 1, wherein in the etching step, (a2) is started before (a1) is completed or simultaneously with (a1) being completed.

3. The substrate processing method of claim 1, wherein the etching step includes: a first etching step in which (a1), (a2), and (b) are started in order, and the supply time of the first modifying gas in (a1) is a first time; and a second etching step in which (a1), (a2), and (b) are started in order, and the supply time of the first modifying gas in (a1) is a second time shorter than the first time; and wherein in the etching step, the first etching step is performed a first number of times, and then the second etching step is performed a second number of times.

4. The substrate processing method according to claim 1, wherein the etching step includes a third etching step in which (a1), (a2), and (b) are started in that order, and a fourth etching step that includes (a2) and (b) but does not include (a1), and in the etching step, the third etching step is performed a third number of times, and then the fourth etching step is performed a fourth number of times.

5. A substrate processing method according to any one of claims 1 to 4, wherein the thickness of the second modified layer formed in (a2) is greater than the thickness of the first modified layer formed in (a1).

6. A substrate processing method according to any one of claims 1 to 4, wherein in (a1), the first modified layer of a first thickness is formed under conditions that saturate the first modified layer with respect to the supply time of the first modifying gas, and (a1) is terminated before the first thickness becomes saturated.

7. The substrate processing method according to claim 6, wherein in (a2), the second modified layer of the second thickness is formed under conditions that saturate the second modified layer with respect to the supply time of the second modifying gas, and (a2) is terminated after the second thickness is saturated.

8. The substrate processing method according to claim 7, wherein the first thickness is set to be smaller than the thickness when the second thickness is saturated.

9. A substrate processing method as described in claim 7, wherein in (a2), a third thickness, which is the thickness of a second modified layer formed in an area where the first modified layer is not formed, is set to be equal to or less than the first thickness.

10. A substrate processing method as described in claim 3, wherein the thickness of the second modified layer formed in the first etching step is made smaller than the thickness of the first modified layer formed in the first etching step, and the thickness of the second modified layer formed in (a2) of the second etching step is made larger than the thickness of the first modified layer formed in (a1) of the second etching step.

11. A substrate processing method as described in claim 10, wherein in the second etching step, the specified material that is present on the surface of the specified material at the end of the first etching step and is deeper than the deepest part of the first modified layer is removed from the substrate.

12. A substrate processing method as described in claim 4, wherein the thickness of the second modified layer formed in the third etching step is made smaller than the thickness of the first modified layer formed in the third etching step, and in the fourth etching step, the specified material present on the surface of the specified material at the end of the third etching step in a region deeper than the deepest part of the first modified layer is removed from the substrate.

13. The substrate processing method according to any one of claims 1 to 4, wherein the first modifying gas and the second modifying gas are fluorine-containing gases, and the first modified layer and the second modified layer are layers containing fluoride.

14. The substrate processing method according to any one of claims 1 to 4, wherein the predetermined substance is a metal oxide substance.

15. The substrate processing method according to any one of claims 1 to 4, wherein the molecular size of the second modifying gas is set larger than the molecular size of the first modifying gas.

16. A substrate processing method according to any one of claims 1 to 4, wherein the predetermined material is a polycrystalline material.

17. A substrate processing method according to any one of claims 1 to 4, wherein in (a1) and (a2), activation of the first modifying gas and the second modifying gas using plasma is not performed.

18. A method for manufacturing a semiconductor device, comprising: (a1) a step of supplying a first modifying gas to a substrate and forming a first modified layer at a first rate on at least a portion of the surface of a predetermined material on the substrate; (a2) a step of supplying a second modifying gas having a molecular structure different from that of the first modifying gas to the substrate and forming a second modified layer at a second rate lower than the first rate on at least a portion of an area on the surface of the predetermined material including the first modified layer; and (b) a step of supplying a reactive gas that reacts with the second modified layer to the substrate and removing at least a portion of the second modified layer from the substrate; and an etching step that starts the above steps in that order.

19. A program that causes a substrate processing apparatus to execute, by a computer, an etching procedure that sequentially starts: (a1) a procedure of supplying a first modifying gas to a substrate and forming a first modified layer at a first rate on at least a portion of the surface of a predetermined material on the substrate; (a2) a procedure of supplying a second modifying gas having a molecular structure different from that of the first modifying gas to the substrate and forming a second modified layer at a second rate lower than the first rate on at least a portion of an area on the surface of the predetermined material that includes the first modified layer; and (b) a procedure of supplying a reactive gas that reacts with the second modified layer to the substrate and removing at least a portion of the second modified layer from the substrate.

20. An etching process comprising: a first modifying gas supply system that supplies a first modifying gas that forms a first modified layer on at least a portion of the surface of a predetermined material on a substrate; a second modifying gas supply system that supplies a second modifying gas that has a molecular structure different from that of the first modifying gas and forms a second modified layer on at least a portion of the surface of the predetermined material; and a reactive gas supply system that supplies a reactive gas that reacts with the second modified layer, the process sequentially comprising: (a1) a process of supplying the first modifying gas to the substrate and forming a first modified layer at a first rate on at least a portion of the surface of the predetermined material; (a2) a process of supplying the second modifying gas to the substrate and forming a second modified layer at a second rate lower than the first rate on at least a portion of an area including the first modified layer on the surface of the predetermined material; and (b) a process of supplying the reactive gas to the substrate and removing at least a portion of the second modified layer from the substrate. a control unit configured to be able to control the first modifying gas supply system, the second modifying gas supply system, and the reactive gas supply system so that the above-mentioned is performed.

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