Processing method, method for producing semiconductor device, program, and processing device

Abstract

The present invention comprises a step of etching a film by carrying out a cycle a predetermined number of times, the cycle including (a) a step of supplying a reformed gas to the film, (b) a step of supplying an inert gas to the film, and (c) a step of supplying an etching gas to the film. At least a part of the duration of step (a) and the duration of step (b) overlaps.

Description

Processing method, semiconductor device manufacturing method, program, and processing device

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

[0002] 2. Description of the Related Art As one step in the manufacturing process of a semiconductor device, a substrate may be etched (see, for example, Japanese Patent Application Laid-Open No. 2003-129998).

[0003] Japanese Patent Application Laid-Open No. 2022-136221

[0004] The present disclosure provides techniques that allow for increased control over etching of a substrate.

[0005] According to one aspect of the present disclosure, there is provided a technology having a process for etching a film by performing a cycle including the steps of (a) supplying a modifying gas to a film, (b) supplying an inert gas to the film, and (c) supplying an etching gas to the film a predetermined number of times, with at least a portion of the period during which (a) is performed overlapping with the period during which (b) is performed.

[0006] According to the present disclosure, it is possible to improve the controllability of etching a substrate.

[0007] FIG. 1 is a schematic diagram of a processing apparatus used in one embodiment, showing a processing furnace 202 in a vertical cross-sectional view. FIG. 2 is a schematic diagram of a processing apparatus used in one embodiment, showing a processing furnace 202 in a cross-sectional view taken along line A-A in FIG. 1. FIG. 3 is a schematic diagram of a controller 121 of the processing apparatus used in one embodiment, showing a control system of the controller 121 in a block diagram. FIG. 4 is a diagram showing a substrate processing sequence in one embodiment. FIG. 5( a) is an enlarged cross-sectional view of a surface of a wafer 200 having a recess formed thereon, which is processed in a substrate processing step in one embodiment. FIG. 5( b) is an enlarged cross-sectional view of the wafer 200 in one embodiment after a modifying gas is supplied to a film 200a formed on the surface of the recess. FIG. 5( c) is an enlarged cross-sectional view of the wafer 200 in one embodiment after an inert gas is supplied to the film 200a. FIG. 5( d) is an enlarged cross-sectional view of the wafer 200 in one embodiment after an etching gas is supplied to the film 200a.

[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 and 5(a) to (d). Note that all drawings used in the following description are schematic, and the dimensional relationships between elements, the ratios of elements, etc. shown in the drawings do not necessarily match those in reality. Furthermore, the dimensional relationships between elements, the ratios of elements, etc. do not necessarily match between multiple drawings.

[0009] (1) Configuration of the Processing Apparatus As shown in Fig. 1, the processing furnace 202 of the processing apparatus has a heater 207 as a temperature adjustment unit (heating unit). The heater 207 is cylindrical and is installed vertically by being supported by a holding plate. The heater 207 also functions as an activation mechanism (excitation unit) that activates (excites) gas by heat.

[0010] A reaction tube 203 is disposed inside the heater 207 concentrically with the heater 207. The reaction tube 203 is made of, for example, quartz (SiO ２ The reaction tube 203 is made of a heat-resistant material such as silicon carbide (SiC) or silicon carbide (SiC) and has a cylindrical shape with a closed top and an open bottom. A manifold 209 is disposed concentrically with the reaction tube 203 below the reaction tube 203. The manifold 209 is made of a metal material such as stainless steel (SUS) and has a cylindrical shape with both top and bottom open. 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 serving as a sealing member is provided between the manifold 209 and the reaction tube 203. The reaction tube 203 is installed vertically, similar to the heater 207. The reaction tube 203 and the manifold 209 mainly constitute a processing vessel (reaction vessel). A processing chamber 201 is formed in the cylindrical hollow portion of the processing vessel. The processing chamber 201 is configured to accommodate wafers 200 as substrates. In this processing chamber 201, processing of the wafer 200 is carried out.

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

[0012] The gas supply pipes 232a to 232c are respectively provided 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, in order from the upstream side of the gas flow. 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. The gas supply pipes 232d and 232e are respectively provided with MFCs 241d and 241e and valves 243d and 243e in order from the upstream side of the gas flow. The gas supply pipes 232a to 232e are made of a metal material, such as SUS.

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

[0014] A 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.

[0015] An etching 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.

[0016] Inert gas is supplied from the gas supply pipes 232c to 232e through the MFCs 241c to 241e, the valves 243c to 243e, the gas supply pipes 232a to 232c, and the nozzles 249a to 249c into the processing chamber 201. The inert gas acts as a purge gas, a carrier gas, a dilution gas, etc.

[0017] A modifying gas supply system (first gas supply system) is mainly constituted by the gas supply pipe 232a, the MFC 241a, and the valve 243a. An etching gas supply system (third gas supply system) is mainly constituted by the gas supply pipe 232b, the MFC 241b, and the valve 243b. An inert gas supply system (second gas supply system) is mainly constituted by the gas supply pipes 232c to 232e, the MFCs 241c to 241e, and the valves 243c to 243e.

[0018] Any or all of the various supply systems described above may be configured as an integrated supply system 248 in which the valves 243a to 243e, the MFCs 241a to 241e, etc. are integrated. The integrated supply system 248 is connected to each of the gas supply pipes 232a to 232e, and is configured so that the supply operation of various substances (various gases) into the gas supply pipes 232a to 232e, i.e., the opening and closing operation of the valves 243a to 243e and the flow rate adjustment operation by the MFCs 241a to 241e, etc., are controlled by a controller 121, which will be described later. The integrated supply system 248 is configured as an integrated or separate integrated unit, and can be attached and detached to and from the gas supply pipes 232a to 232e, etc., so that maintenance, replacement, expansion, etc. of the integrated supply system 248 can be performed on an integrated unit basis.

[0019] An exhaust port 231a for exhausting the atmosphere inside the process chamber 201 is provided at the bottom of the sidewall of the reaction tube 203. As shown in FIG. 2, the exhaust port 231a is provided at a position facing the nozzles 249a to 249c (gas supply holes 250a to 250c) across the wafer 200 in a plan view. The exhaust port 231a may be provided along the sidewall of the reaction tube 203 from the bottom to the top, i.e., along the wafer arrangement area. An exhaust pipe 231 is connected to the exhaust port 231a. A vacuum pump 246 serving as a vacuum exhaust device is connected to the exhaust pipe 231 via a pressure sensor 245 serving as a pressure detector (pressure detection unit) for detecting the pressure inside the process chamber 201 and an APC (Auto Pressure Controller) valve 244 serving as a pressure regulator (pressure adjustment unit). The APC valve 244 is configured to be able to evacuate and stop the evacuation of the processing chamber 201 by opening and closing the valve while the vacuum pump 246 is operating, and further, to be able to adjust the pressure inside the processing chamber 201 by adjusting the valve opening based on pressure information detected by the pressure sensor 245 while the vacuum pump 246 is operating. An exhaust system is mainly configured by the exhaust pipe 231, the APC valve 244, and the pressure sensor 245. The vacuum pump 246 may be included in the exhaust system.

[0020] A seal cap 219 (hereinafter referred to as the cap 219) serving as a furnace port cover capable of airtightly closing the lower end opening of the manifold 209 is provided below the manifold 209. The cap 219 is made of a metal material such as SUS and is formed in a disk shape. An O-ring 220b serving as a sealing member that abuts against the lower end of the manifold 209 is provided on the upper surface of the cap 219. A rotation mechanism 267 for rotating a boat 217 (described later) is provided below the cap 219. A rotation shaft 255 of the rotation mechanism 267 passes through the cap 219 and is connected to the boat 217. The rotation mechanism 267 is configured to rotate the boat 217, thereby rotating the wafers 200. The cap 219 is configured to be vertically raised and lowered by a boat elevator 115 (hereinafter referred to as the elevator 115) serving as an elevating mechanism installed outside the reaction tube 203. The elevator 115 is configured as a transfer device (transfer mechanism) that transfers the wafer 200 into and out of the processing chamber 201 by raising and lowering the cap 219 .

[0021] A shutter 219s is provided below the manifold 209 as a furnace port cover that can airtightly close the lower end opening of the manifold 209 when the cap 219 is lowered and the boat 217 is unloaded from the process chamber 201. The shutter 219s is made of a metal material such as SUS and has a disk shape. An O-ring 220c is provided on the upper surface of the shutter 219s as a sealing member that abuts against the lower end of the manifold 209. The opening and closing operation (lifting and lowering operation, rotating operation, etc.) of the shutter 219s is controlled by a shutter opening and closing mechanism 115s.

[0022] The boat 217 serving as a substrate support is configured to support a plurality of wafers 200, for example, 25 to 200 wafers 200, in multiple stages, in a horizontal position, with their centers aligned and aligned vertically, i.e., arranged at intervals. The boat 217 is made of a heat-resistant material such as quartz or SiC. At the bottom of the boat 217, heat insulating plates 218, also made of a heat-resistant material such as quartz or SiC, are supported in multiple stages.

[0023] A temperature sensor 263 serving as a temperature detector is installed inside the reaction tube 203. By adjusting the power supply to the heater 207 based on temperature information detected by the temperature sensor 263, the temperature distribution inside the processing chamber 201 becomes a desired one. The temperature sensor 263 is installed along the inner wall of the reaction tube 203.

[0024] As shown in FIG. 3 , the controller 121, which is a control unit (control means), is configured as a computer including a CPU (Central Processing Unit) 121a, a RAM (Random Access Memory) 121b, a storage device 121c, and an I / O port 121d. The RAM 121b, the storage device 121c, and the I / O port 121d are configured to be able to exchange data with the CPU 121a via an internal bus 121e. An input / output device 122, such as a touch panel, is connected to the controller 121. An external storage device 123 can also be connected to the controller 121. Note that the processing device may be configured to include one control unit or multiple control units. That is, the control for performing the processing sequence described below may be performed using one control unit or multiple control units. Furthermore, the multiple control units may be configured as a control system connected to each other via a wired or wireless communication network, and the control for carrying out the processing sequence described below may be performed by the entire control system. When the term "control unit" is used in this specification, it may include not only one control unit but also multiple control units or a control system configured by multiple control units.

[0025] The storage device 121c is composed of, for example, a flash memory, a hard disk drive (HDD), a solid state drive (SSD), etc. Control programs for controlling the operation of the processing device, process recipes describing procedures and conditions for substrate processing (described later), etc., are readably recorded and stored in the storage device 121c. The process recipe is a combination of procedures for substrate processing (described later) that are executed by the controller 121 in the processing device to obtain a predetermined result, and functions as a program. Hereinafter, the process recipes, control programs, etc. are collectively referred to simply as programs. The process recipes are also simply referred to as recipes. In this specification, the term "program" may refer to a recipe alone, a control program alone, or both. The RAM 121b is configured as a memory area for temporarily storing programs, data, etc. read by the CPU 121a.

[0026] The I / O port 121d is connected to the above-mentioned MFCs 241a to 241e, valves 243a to 243e, pressure sensor 245, APC valve 244, vacuum pump 246, temperature sensor 263, heater 207, rotation mechanism 267, elevator 115, shutter opening / closing mechanism 115s, and the like.

[0027] The CPU 121a is configured to read and execute a control program from the storage device 121c, and to read a recipe from the storage device 121c in response to input of an operation command from the input / output device 122. The CPU 121a is configured to control, in accordance with the contents of the read recipe, the flow rate adjustment operation of various substances (various gases) by the MFCs 241a to 241e, the opening and closing operation of the valves 243a to 243e, 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 elevator 115, the opening and closing operation of the shutter 219s by the shutter opening and closing mechanism 115s, and the like.

[0028] The controller 121 can be configured by installing the above-mentioned program recorded and 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, or a semiconductor memory such as a USB memory or an SSD. The storage device 121c and the external storage device 123 are configured as computer-readable recording media 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.

[0029] (2) Substrate Processing Step An example of a processing sequence for etching a wafer 200 as a substrate using the above-described processing device (substrate processing device) as one step in the manufacturing process of a semiconductor device will be described mainly with reference to Figure 4 and Figures 5(a) to 5(d). In the following description, the operation of each part constituting the processing device is controlled by a controller 121.

[0030] The wafer 200 processed in the substrate processing step according to one embodiment of the present disclosure may be, for example, a Si substrate made of single-crystal silicon (Si). The surface of the wafer 200 has recesses such as trenches and holes formed thereon, with a native oxide film 200a such as a silicon oxide film (SiO film) formed thereon, as shown in FIG. 5( a). Hereinafter, the native oxide film 200a may be simply referred to as the film 200a.

[0031] As shown in FIG. 4 , the processing sequence in this embodiment includes a step of etching the film 200a by performing a cycle including: (a) step A of supplying a modifying gas to the film 200a; (b) step B of supplying an inert gas to the film 200a; and (c) step C of supplying an etching gas to the film 200a a predetermined number of times (n times, where n is an integer of 1 or 2 or more), and in the cycle, the period during which step A is performed and the period during which step B is performed are at least partially overlapped.

[0032] 4, in the processing sequence of this embodiment, step A is started before step B, and step B is started while step A is still being executed. In this embodiment, a case where step B is performed in the latter half of the period during which step A is executed will be described.

[0033] In this embodiment, as an example, a case will be described in which a step of increasing the temperature inside the processing chamber 201 (hereinafter referred to as step D) is performed after step C is performed.

[0034] In this specification, the above-described processing sequence may be expressed as follows for convenience: Similar notations will be used in the following explanations of modified examples and other aspects.

[0035] (modifying gas + inert gas → etching gas → temperature increase) × n

[0036] 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, "etching a predetermined layer on a wafer" may mean directly etching a predetermined layer on the surface of the wafer itself or etching 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".

[0037] The term "substance" as used herein includes at least one of a gaseous substance and a liquid substance. A liquid substance includes a mist-like substance. That is, a substance may include a gaseous substance, a liquid substance such as a mist-like substance, or both.

[0038] (Loading and Boat Loading) When a plurality of wafers 200 are loaded into the boat 217, the shutter 219s is moved by the shutter opening / closing mechanism 115s to open the lower end opening of the manifold 209. Thereafter, as shown in FIG. 1 , the boat 217 supporting the plurality of wafers 200 is lifted by the elevator 115 and carried into the processing chamber 201 (boat loading). In this state, the cap 219 seals the lower end of the manifold 209 via the O-ring 220b. In this manner, the wafers 200 are prepared (provided) in the processing chamber 201.

[0039] (Pressure Adjustment and Temperature Adjustment) After the boat loading is completed, 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 that the desired pressure (vacuum level) is reached. At this time, the pressure inside the processing chamber 201 is measured by the pressure sensor 245, and the APC valve 244 is feedback-controlled based on this measured pressure information. Furthermore, the wafers 200 inside the processing chamber 201 are heated by the heater 207 so that the desired processing temperature is reached. At this time, the power supply to the heater 207 is feedback-controlled based on temperature information detected by the temperature sensor 263 so that the desired temperature distribution is achieved inside the processing chamber 201. Furthermore, the rotation mechanism 267 starts to rotate the wafers 200. The evacuation inside the processing chamber 201 and the heating and rotation of the wafers 200 are all continued at least until the processing of the wafers 200 is completed.

[0040] (Etching) Thereafter, the following steps A to D are carried out in this order.

[0041] [Step A] In this step, a modifying gas is supplied to the wafer 200 in the processing chamber 201, that is, to the film 200a formed on the surface of the wafer 200.

[0042] Specifically, the valve 243a is opened to allow the modifying gas to flow into the gas supply pipe 232a. The flow rate of the modifying gas is adjusted by the MFC 241a, supplied into the processing chamber 201 via the nozzle 249a, and exhausted from the exhaust port 231a. At this time, the modifying gas is supplied to the wafer 200 from a direction different from the bottom direction of the recess on the surface of the wafer 200 (modifying gas supply). In this specification, the bottom direction of the recess refers to a direction perpendicular to the upper surface of the recess. The direction different from the bottom direction of the recess refers to, for example, a direction approximately perpendicular to the bottom direction of the recess. Note that, when the recess is formed extending in the thickness direction of the wafer 200, the direction different from the bottom direction of the recess is a direction substantially parallel to the surface of the wafer 200. Furthermore, when the recess is formed extending in a direction substantially parallel to the surface of the wafer 200, the direction different from the bottom direction of the recess is a direction perpendicular to the surface of the wafer 200.

[0043] Examples of processing conditions for supplying the modified gas in this step include: Processing temperature: 20 to 75°C, preferably 25 to 70°C Processing pressure: 1 to 10,000 Pa, preferably 10 to 1,333 Pa Modified gas supply flow rate: 0.01 to 3 slm, preferably 0.1 to 1 slm Modified gas supply time: 30 to 1,800 seconds, preferably 50 to 1,200 seconds. The processing pressure in this step is preferably higher than the processing pressure in step C, which will be described later. Furthermore, in this step, it is preferable to bring the modified gas to the above processing pressure in an undecomposed state.

[0044] In this specification, when a numerical range such as "20 to 75°C" is expressed, both the lower and upper limits are included in the range. For example, "20 to 75°C" means "20°C or higher and 75°C or lower." The same applies to other numerical ranges. In this specification, the term "processing temperature" refers to the temperature of the wafer 200 or the temperature inside the processing chamber 201, and the term "processing pressure" refers to the pressure inside the processing chamber 201, in other words, the pressure in the space in which the wafer 200 is present. Furthermore, the term "processing time" refers to the time the processing continues. Furthermore, when the supply flow rate includes 0 slm, 0 slm means that the substance (gas) is not supplied. These terms also apply to the following description.

[0045] By supplying the modifying gas to the wafer 200 (film 200a) under the above-described processing conditions, at least one of the modifying gas, a substance having a part of the molecular structure of the modifying gas, and a predetermined element contained in the modifying gas can be adsorbed on the surface of the film 200a (see FIG. 5(b)). Hereinafter, at least one of the modifying gas, a substance having a part of the molecular structure of the modifying gas, and a predetermined element contained in the modifying gas may be referred to as the modifying gas, etc. In FIGS. 5(b) to 5(d), the modifying gas, etc. is indicated by the letter α.

[0046] By supplying the modifying gas to the wafer 200 (film 200a) under the above-described processing conditions, the modifying gas is filled from the top surface of the opening side of the recess formed in the wafer 200 (hereinafter referred to as the top surface of the recess) to the bottom surface inside the recess (hereinafter referred to as the bottom surface of the recess), and the modifying gas etc. is adsorbed to the top surface of the recess and the inside side and bottom surfaces of the recess (hereinafter referred to as the side and bottom surfaces of the recess). At this time, the modifying gas etc. is preferentially adsorbed to the top surface of the recess rather than the side and bottom surfaces of the recess. In other words, the amount of the modifying gas etc. adsorbed to the top surface of the recess is greater than the amount of the modifying gas etc. adsorbed to the side and bottom surfaces of the recess (see FIG. 5(b)).

[0047] The reforming gas may be, for example, ammonia (NH ３ ) gas, hydrazine (N ２ H ４ ) gas, pyridine (C ５ H ５ N) gas, pyrimidine (C ４ H ４ N ２ ) gas, picoline (C ６ H ７ As the modifying gas, one or more of these gases can be used.

[0048] [Step B] After a predetermined time has elapsed since the start of step A, an inert gas is supplied to the wafer 200 in the processing chamber 201, i.e., to the film 200a on which the modifying gas or the like has been adsorbed, while continuing to perform step A (see FIG. 4).

[0049] Specifically, in the latter half of the period during which step A is performed, once the modifying gas or the like has been adsorbed onto the top, side, and bottom surfaces of the recesses, i.e., the entire surface of the recesses, the valves 243c to 243e are opened while the supply of the modifying gas is continued, and an inert gas is allowed to flow into the gas supply pipes 232c to 232e. The flow rate of the inert gas is adjusted by the MFCs 241c to 241e, and the inert gas is supplied into the processing chamber 201 via the nozzles 249a to 249c and exhausted from the exhaust port 231a. At this time, the inert gas is supplied to the wafer 200 from a direction different from the bottom of the recesses (inert gas supply).

[0050] Examples of processing conditions for supplying an inert gas in this step include: processing temperature: 20 to 75°C, preferably 25 to 70°C; processing pressure: 1 to 10,000 Pa, preferably 10 to 1,333 Pa; inert gas supply flow rate: 0.01 to 3 slm, preferably 0.1 to 1 slm; and inert gas supply time: 10 to 300 seconds, preferably 20 to 60 seconds. The execution time of this step (inert gas supply time) is preferably shorter than the execution time of step A (modifying gas supply time). In addition, the supply amount of the inert gas in this step is preferably smaller than the supply amount of the modifying gas in step A. The gas supply amount can be calculated by multiplying the gas supply flow rate by the gas supply time.

[0051] Under the above conditions, by supplying an inert gas to the film 200a to which the modifying gas or the like is adsorbed, for example, from a direction other than the bottom direction of the recess, a portion of the modifying gas or the like adsorbed (laminate) on the upper surface of the recess can be peeled off and removed (desorbed) from the upper surface of the recess (see FIG. 5(c)). On the other hand, supplying an inert gas under the above conditions hardly peels off the modifying gas or the like adsorbed on the side and bottom surfaces of the recess. In this way, the amount of the modifying gas or the like adsorbed on the surface of the recess can be adjusted, and in this embodiment, the amount of the modifying gas or the like adsorbed on the upper surface of the recess can be made smaller than the amount of the modifying gas or the like adsorbed on the side and bottom surfaces of the recess (see FIG. 5(c)). Note that in FIG. 5(c), the flow of the inert gas is indicated by arrows.

[0052] The inert gas may be, for example, nitrogen (N ２ Inert gases that can be used include rare gases such as argon (Ar) gas, helium (He) gas, neon (Ne) gas, and xenon (Xe) gas. One or more of these gases can be used as the inert gas. This also applies to the steps described below.

[0053] Thereafter, the valves 243a and 243c to 243e are closed to stop the supply of the modifying gas and the inert gas into the processing chamber 201. Then, the processing chamber 201 is evacuated to remove gaseous substances remaining in the processing chamber 201. At this time, the valves 243c to 243e may be left open and an inert gas may be supplied into the processing chamber 201 through the nozzles 249a to 249c. The inert gas supplied through the nozzles 249a to 249c acts as a purge gas, thereby purging the space in which the wafer 200 is present, i.e., the processing chamber 201.

[0054] [Step C] After steps A and B are completed, an etching gas is supplied to the wafer 200 in the processing chamber 201, that is, to the film 200a on which the modifying gas or the like is adsorbed (see FIG. 4).

[0055] Specifically, the valve 243b is opened to allow the etching gas to flow into the gas supply pipe 232b. The etching gas has a flow rate adjusted by the MFC 241b, is supplied into the processing chamber 201 via the nozzle 249b, and is exhausted from the exhaust port 231a. At this time, the etching gas is supplied to the wafer 200 (etching gas supply). At this time, the valves 243c to 243e may be opened to supply an inert gas into the processing chamber 201 via the nozzles 249a to 249c, respectively.

[0056] Examples of processing conditions for supplying the etching gas in this step include: processing temperature: 25 to 75°C, preferably 25 to 70°C processing pressure: 1 to 10,000 Pa, preferably 10 to 1,333 Pa etching gas supply flow rate: 0.01 to 3 slm, preferably 0.1 to 1 slm etching gas supply time: 10 to 120 seconds, preferably 20 to 60 seconds inert gas supply flow rate (per gas supply pipe): 0 to 10 slm

[0057] By supplying an etching gas to the wafer 200 (film 200a) under the above-described processing conditions, at least one of the etching gas, a substance having a part of the molecular structure of the etching gas, and a predetermined element contained in the etching gas can be adsorbed by the modifying gas adsorbed on the surface of the film 200a (see FIG. 5(d)). Hereinafter, at least one of the etching gas, a substance having a part of the molecular structure of the etching gas, and a predetermined element contained in the etching gas may be referred to as the etching gas, etc. Note that in FIG. 5(d), the etching gas, etc. is indicated by the letter β.

[0058] By supplying the etching gas to the film 200a under the above-described processing conditions, the etching gas can reach from the top surface of the recess formed in the wafer 200 to the bottom surface of the recess, and the etching gas and the like can be adsorbed onto the top surface, side surface, and bottom surface of the recess. At this time, the etching gas and the like are preferentially adsorbed onto the top surface of the recess rather than the side surface and bottom surface of the recess. In other words, the amount of the etching gas and the like adsorbed onto the top surface of the recess is greater than the amount of the etching gas and the like adsorbed onto the side surface and bottom surface of the recess (see FIG. 5(d)).

[0059] The etching gas may be, for example, hydrogen fluoride (HF) gas or chlorine trifluoride (ClF ３ ) gas, fluorine (F ２ ), nitrogen trifluoride (NF ３ ) gas, carbon tetrafluoride (CF ４ Fluorine (F)-containing gases such as fluorine (F) gas can be used. As the etching gas, one or more of these can be used.

[0060] After the etching gas and the like are adsorbed by the modifying gas and the like adsorbed on the surface of the film 200a, the valve 243b is closed to stop the supply of the etching gas into the processing chamber 201. Then, the processing chamber 201 is evacuated to remove gaseous substances and the like remaining in the processing chamber 201. At this time, the valves 243c to 243e are opened to supply an inert gas into the processing chamber 201 through the nozzles 249a to 249c. The inert gas supplied from the nozzles 249a to 249c acts as a purge gas, thereby purging the space in which the wafer 200 exists, i.e., the processing chamber 201.

[0061] [Step D] The output of the heater 207 is adjusted so that the temperature inside the processing chamber 201, i.e., the temperature of the wafers 200, is raised to a predetermined temperature. The processing chamber 201, i.e., the space in which the wafers 200 are present, is evacuated by the vacuum pump 246 to a predetermined pressure. This step is preferably performed in an inert gas atmosphere. That is, when performing this step, it is preferable to open the valves 243c to 243e and supply an inert gas into the processing chamber 201 through the nozzles 249a to 249c to purge the processing chamber 201.

[0062] Examples of the treatment conditions in this step include: treatment temperature: 100 to 200° C., preferably 150 to 200° C. treatment pressure: 1 to 10,000 Pa, preferably 10 to 1,333 Pa treatment time: 0.5 to 5 hours inert gas supply flow rate (per gas supply pipe): 0 to 10 slm.

[0063] The film 200a can be etched by subjecting the wafer 200 to a temperature increase treatment (heat treatment) under the above-described processing conditions. Hereinafter, the etching process of the film 200a will be described assuming that the film 200a formed on the surface of the recess is a SiO film and that NH is used as a modifying gas. ３ The case where HF gas is used as the etching gas will be described as an example. Steps A and C are performed under the above-mentioned processing conditions, and NH ３ When the gas (modifying gas) and the HF gas (etching gas) are supplied, NH ３ The NH gas and HF gas are adsorbed and react with the SiO film.３ The SiO film reacted with the HF gas and ammonium hexafluorosilicate (NH ４ ) SiF ６ Then, step D is performed under the above-described processing conditions, and the wafer 200 is subjected to a temperature increase process, whereby the (NH ４ ) SiF ６ The film is sublimated and removed (etched).

[0064] After etching the film 200a, the processing chamber 201 is evacuated to remove gaseous substances remaining in the processing chamber 201. At this time, valves 243c to 243e are opened, and an inert gas is supplied into the processing chamber 201 through nozzles 249a to 249c. The inert gas supplied from the nozzles 249a to 249c acts as a purge gas, thereby purging the space in which the wafers 200 are present, i.e., the processing chamber 201. At this time, the temperature inside the processing chamber 201 is lowered to the processing temperature in step A, as necessary.

[0065] [Performance Predetermined Number of Times] By performing a cycle of performing the above-described steps A to D in this order n times (n is an integer of 1 or 2 or more), it is possible to etch the film 200a formed on the surface of the wafer 200 to a desired depth. It is preferable to repeat the above-described cycle multiple times. In other words, it is preferable to set the thickness of the film etched per cycle to be thinner than the desired thickness, and to repeat the above-described cycle multiple times until the thickness of the film removed by etching reaches the desired thickness.

[0066] (Purge and Return to Atmospheric Pressure) After the etching process is completed, an inert gas is supplied as a purge gas from each of the nozzles 249a to 249c into the process chamber 201 and exhausted from the exhaust port 231a. This purges the process chamber 201, and gases and reaction by-products remaining in the process chamber 201 are removed from the process chamber 201. Thereafter, the atmosphere in the process chamber 201 is replaced with the inert gas, and the pressure in the process chamber 201 is returned to normal pressure (atmospheric pressure).

[0067] (Transportation and Wafer Removal) Thereafter, the cap 219 is lowered by the elevator 115, and the lower end of the manifold 209 is opened. Then, the processed wafers 200, supported by the boat 217, are transferred from the lower end of the manifold 209 to the outside of the reaction tube 203. After the transfer, the shutter 219s is moved, and the opening at the lower end of the manifold 209 is sealed by the shutter 219s via the O-ring 220c. After the processed wafers 200 are transferred to the outside of the reaction tube 203, they are removed from the boat 217.

[0068] (3) Effects of this Embodiment According to this embodiment, one or more of the following effects can be obtained.

[0069] (a) By overlapping at least a portion of the period during which step A is performed with the period during which step B is performed, the amount of modifying gas adsorbed on the surface of the film 200a can be adjusted. This allows the etching amount of the film 200a to be adjusted (controlled). In particular, when a recess is formed on the surface of the wafer 200, the amount of modifying gas present on the top surface of the recess can be made different from the amount of modifying gas present on the side and bottom surfaces of the recess. In other words, the amount of modifying gas present on the opening side of the recess can be made different from the amount of modifying gas present on the bottom side of the recess. This allows the etching amount of the film 200a formed on the top surface of the recess and the film 200a formed on the side and bottom surfaces of the recess to be adjusted (controlled). These are explained below. The amount of modifying gas present refers to the amount of molecules or a portion of molecules of the material that constitutes the modifying gas. The modifying gas also includes substances floating in the space within the recess and substances adsorbed on each surface within the recess.

[0070] For example, when gas is supplied to a wafer 200 having a recess formed on its surface, the supplied gas tends to preferentially adsorb to the upper surface of the recess. That is, the amount of modifying gas or etching gas adsorbed to the upper surface of the recess is greater than the amount of modifying gas or etching gas adsorbed to the side and bottom surfaces of the recess. Therefore, when etching a film 200a formed on the surface of the recess, the upper surface of the recess is etched more than the side and bottom surfaces of the recess, making it difficult to uniformly etch the film 200a.

[0071] In this embodiment, the period during which step A is performed and the period during which step B is performed are partially overlapped. Specifically, while a modifying gas is supplied to the film 200a in step A, an inert gas is supplied to the film 200a in step B. This allows a portion of the modifying gas adsorbed to the upper surface of the recess to be removed (desorbed) by flowing the inert gas (see FIG. 5C). In this way, the amount of modifying gas adsorbed (present) on the upper surface of the recess can be reduced. When an etching gas is then supplied to the film 200a in step C, the etching gas preferentially adsorbs to the upper surface of the recess, but the amount of modifying gas adsorbed to the upper surface of the recess is small, so the amount of etching of the film 200a on the upper surface of the recess is suppressed. On the other hand, the modifying gas adsorbed (present) on the side and bottom surfaces of the recess is hardly affected by the inert gas supplied in step B. Therefore, the amount of modifying gas present on the side and bottom surfaces of the recess is hardly reduced. Therefore, in step C, the film 200a formed on the side and bottom surfaces of the recess is etched with almost no effect from the inert gas supplied in step B. In this way, the etching amount of the film 200a on the top surface and the side and bottom surfaces of the recess can be adjusted (controlled). As a result, the film 200a can be etched uniformly.

[0072] (b) By making the pressure in the processing chamber 201 in step A higher than the pressure in the processing chamber 201 in step C, that is, by performing step A under a relatively high pressure, the inside of the recess can be filled with the modifying gas, and the modifying gas can be adsorbed uniformly from the opening of the recess to the bottom surface.

[0073] (c) By performing step B in the latter half of the implementation period of step A, the amount of modifying gas, etc. present on the top surface of the recess can be made smaller than the amount of modifying gas, etc. present on the side and bottom surfaces of the recess. Specifically, by performing step B in the latter half of the implementation period of step A, the inert gas is supplied after the modifying gas has filled the recess from the top surface to the bottom surface of the recess. Since the inert gas is preferentially supplied to the top surface of the recess, the modifying gas, etc. present on the top surface of the recess is removed (desorbed) by the inert gas. In contrast, the modifying gas, etc. present on the side and bottom surfaces of the recess is hardly affected by the inert gas and remains inside the recess. This makes it possible to make the amount of modifying gas, etc. present on the top surface of the recess smaller than the amount of modifying gas, etc. present on the side and bottom surfaces of the recess.

[0074] (d) The implementation time of step B is shorter than the implementation time of step A, thereby improving the controllability of the amount of the modifying gas, etc. adsorbed to the film 200a (remaining on the film 200a). Specifically, by relatively shortening the implementation time of step B, the inert gas can be supplied instantaneously for only a short time, so that the modifying gas, etc. present on the top surface of the recess can be reduced without substantially reducing the modifying gas, etc. present on the side and bottom surfaces of the recess.

[0075] (e) The amount of inert gas supplied in step B is less than the amount of modifying gas supplied in step A, which improves the controllability of the amount of modifying gas adsorbed to the film 200a.

[0076] (4) Modifications The processing sequence in this embodiment can be modified as shown in the following modifications. These modifications can be combined as desired. Unless otherwise specified, the processing procedures and processing conditions in each step of each modification can be the same as the processing procedures and processing conditions in each step of the above-described processing sequence.

[0077] (Modification 1) Step B may be performed midway (i.e., halfway through) the implementation period of step A. In this modification, the same effects as those of the above-described embodiment can be obtained.

[0078] (Variation 2) Steps A to D may be performed in the order of steps B, A, C, and D, while the supply of the inert gas is continued in step B. Step A may be started to supply the modifying gas. Specifically, step A may be performed in the latter half of the period during which step B is performed.

[0079] This modification also achieves at least some of the effects described in the above embodiment. Furthermore, by performing step A later in the implementation period of step B, this modification can increase the amount of modifying gas, etc. present on the upper surface of the recessed portion relative to the amount of modifying gas, etc. present on the side and bottom surfaces of the recessed portion. Because step A is performed later in the implementation period of step B, the modifying gas is supplied after the interior of the recessed portion is filled with inert gas. Because the interior of the recessed portion is filled with inert gas and the modifying gas is preferentially supplied to the upper surface of the recessed portion, most of the supplied modifying gas is adsorbed to the upper surface of the recessed portion. In this way, the amount of modifying gas, etc. present on the upper surface of the recessed portion can be increased relative to the amount of modifying gas, etc. present on the side and bottom surfaces of the recessed portion. As a result, the film 200a formed on the upper surface of the recessed portion can be selectively etched. This modification is particularly useful when a process for widening the opening of a recessed portion is desired.

[0080] (Variation 3) Steps A to D may be performed in the order of steps B, A, C, and D, while the supply of inert gas is continued in step B. Step A may be started to supply the modifying gas. Specifically, step A may be performed midway (i.e., midway or in the middle) during the period in which step B is performed.

[0081] This modification can also achieve at least some of the effects described in the above embodiment. Furthermore, by performing step A midway through the implementation period of step B, this modification can increase the amount of modifying gas, etc. present on the upper surface of the recessed portion relative to the amount of modifying gas, etc. present on the side and bottom surfaces of the recessed portion. Because step A is performed midway through the implementation period of step B, the modifying gas is supplied after the interior of the recessed portion is filled to a certain extent with inert gas. Since the interior of the recessed portion is filled to a certain extent with inert gas and the modifying gas is preferentially supplied to the upper surface of the recessed portion, most of the supplied modifying gas is adsorbed to the upper surface of the recessed portion. In this way, the amount of modifying gas, etc. present on the upper surface of the recessed portion can be increased relative to the amount of modifying gas, etc. present on the side and bottom surfaces of the recessed portion. As a result, the film 200a formed on the upper surface of the recessed portion can be selectively etched. This modification is useful when a process is desired to widen the opening of the recessed portion.

[0082] (Variation 4) As shown in the processing sequence below, step E may be further included, in which an inert gas is supplied to the film 200a during the period in which step C is performed. Specifically, step E may be started to supply the inert gas while the supply of etching gas is continuing in step C. Step E may be performed in the latter half of the period in which step C is performed, or may be performed in the middle (i.e., midway or mid-stage) of the period in which step C is performed. In this variation, the period in which step E is performed is preferably shorter than the period in which step C is performed. In addition, the amount of inert gas supplied in step E is preferably smaller than the amount of etching gas supplied in step C.

[0083] (modifying gas + inert gas → etching gas + inert gas → temperature increase process) × n

[0084] This modification also provides the same effects as those of the above-described embodiment. Furthermore, in this modification, by performing step E, the flow of etching gas present on film 200a can be improved, thereby improving the controllability of the amount of etching gas remaining on film 200a. By performing step E in the latter half or middle of the period during which step C is performed, the controllability of the amount of etching gas, etc. present on the upper surface of the recess can be improved. By shortening the time for performing step E compared to the time for performing step C and reducing the amount of inert gas supplied in step E and the amount of etching gas supplied in step C, the controllability of the amount of etching gas, etc. present on the upper surface of the recess can be improved.

[0085] 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.

[0086] For example, in the above-described embodiment, the film 200a to be etched is formed on the surface of the wafer 200. However, the present disclosure is not limited to this embodiment. For example, the film 200a to be etched may be formed on the reaction tube 203 or the like. In this embodiment, the same effects as those in the above-described embodiment can be obtained.

[0087] For example, in the above-described embodiment, a case where a wafer 200 having recesses formed on its surface is used has been described as an example. However, the present disclosure is not limited to such an embodiment. For example, a wafer 200 having no recesses formed on its surface may be used. In this embodiment, the same effects as those of the above-described embodiment can be obtained.

[0088] Although not specifically described in the above embodiment, an inert gas may be supplied in pulses in step B or step E. This embodiment also provides the same effects as the above embodiment. This embodiment further improves the controllability of the amount of modifying gas and etching gas remaining on the film 200a.

[0089] For example, in the above-described embodiment, a case where a SiO film is formed on the surface of the recess is described as an example. However, the present disclosure is not limited to such an embodiment. For example, a silicon nitride film (SiN film) may be formed. Also, a film containing a metal element may be formed. Note that a film containing a metal element is a film of a simple metal element, or a film containing a metal element and at least one of oxygen, nitrogen, and carbon. In this embodiment, the same effects as those in the above-described embodiment can be obtained.

[0090] It is preferable that the recipes used for each process be individually prepared according to the process content and recorded and stored in the storage device 121c via an electric communication line or the external storage device 123. When starting each process, it is preferable that the CPU 121a appropriately selects an appropriate recipe according to the process content from among the multiple recipes recorded and stored in the storage device 121c. This enables the processing device to etch films of various film types, composition ratios, film qualities, and film thicknesses with good reproducibility. It also reduces the burden on the operator, avoids operational errors, and enables each process to be started quickly.

[0091] The above-mentioned recipes do not necessarily have to be newly created, but may be prepared by modifying an existing recipe already installed in the processing device. When modifying a recipe, the modified recipe may be installed in the processing device via an electric communication line or a recording medium on which the recipe is recorded. Furthermore, an existing recipe already installed in the processing device may be directly modified by operating the input / output device 122 provided in the existing processing device.

[0092] In the above-described embodiment, an example of etching a film using a batch-type processing apparatus that processes multiple substrates at a time has been described. The present disclosure is not limited to the above-described embodiment and can be suitably applied, for example, to etching a film using a single-wafer processing apparatus that processes one or several substrates at a time. Furthermore, in the above-described embodiment, an example of etching a film using a processing apparatus having a hot-wall processing furnace has been described. The present disclosure is not limited to the above-described embodiment and can be suitably applied to etching a film using a processing apparatus having a cold-wall processing furnace.

[0093] In the above-described embodiment, the processing sequence is performed in the same processing chamber of the same processing apparatus (in-situ). The present disclosure is not limited to the above-described embodiment, and for example, one step and another step of the processing sequence may be performed in different processing chambers of different processing apparatuses (ex-situ), or may be performed in different processing chambers of the same processing apparatus.

[0094] When using these processing devices, each process can be performed using the same processing procedures and conditions as in the above-described embodiments and modifications, and the same effects as in the above-described embodiments and modifications can be obtained.

[0095] 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.

[0096] 200a membrane

Claims

1. A processing method comprising the step of etching a film by performing a cycle including the steps of: (a) supplying a modifying gas to the film; (b) supplying an inert gas to the film; and (c) supplying an etching gas to the film a predetermined number of times, with at least a portion of the period during which (a) is performed overlapping with the period during which (b) is performed.

2. The processing method according to claim 1, wherein the implementation time of (b) is shorter than the implementation time of (a).

3. The processing method according to claim 1, wherein in (b), the inert gas is supplied in pulses.

4. The method of claim 1, wherein (b) is carried out during the latter half of the period during which (a) is carried out.

5. The method of claim 1, wherein (b) is carried out midway through the period during which (a) is carried out.

6. The processing method according to claim 1, wherein the amount of the inert gas supplied in (b) is smaller than the amount of the modifying gas supplied in (a).

7. The method of claim 1, wherein (a) is carried out during the latter half of the period during which (b) is carried out.

8. The method of claim 1, wherein (a) is carried out midway through the period during which (b) is carried out.

9. The method of claim 1, further comprising the step of: (e) supplying said inert gas to said membrane during (c).

10. The processing method according to claim 9, wherein the implementation time of (e) is shorter than the implementation time of (c).

11. The method according to claim 9, wherein in (e), the inert gas is supplied in pulses.

12. The method of claim 9, wherein (e) is carried out during the latter half of the period during which (c) is carried out.

13. The method of claim 9, wherein (e) is performed midway through the implementation period of (c).

14. The processing method according to claim 13, wherein the supply amount of the inert gas in (e) is smaller than the supply amount of the etching gas in (c).

15. The processing method according to any one of claims 1 to 14, wherein a recess is provided on the surface of the substrate on which the film is formed.

16. The processing method according to claim 15, wherein the modifying gas and the inert gas are supplied from a direction different from a direction toward a bottom of the recess.

17. The processing method according to claim 15, wherein the pressure in the space in which the substrate is present in (a) is made higher than the pressure in the space in which the substrate is present in (c).

18. A method for manufacturing a semiconductor device, comprising: a step of etching the film by performing a cycle including: (a) a step of supplying a modifying gas to the film; (b) a step of supplying an inert gas to the film; and (c) a step of supplying an etching gas to the film a predetermined number of times, with at least a portion of the period during which (a) is performed overlapping with the period during which (b) is performed.

19. A program that causes a processing device to execute, via a computer, a procedure for etching a film by performing a cycle including: (a) a procedure for supplying a modifying gas to the film; (b) a procedure for supplying an inert gas to the film; and (c) a procedure for supplying an etching gas to the film a predetermined number of times, with at least a portion of the period during which (a) is performed overlapping with the period during which (b) is performed.

20. A processing apparatus comprising: a first gas supply system for supplying a modifying gas to a film; a second gas supply system for supplying an inert gas to the film; a third gas supply system for supplying an etching gas to the film; and a control unit configured to be capable of controlling the first gas supply system, the second gas supply system, and the third gas supply system so as to perform a process of etching the film by performing a cycle including: (a) a process of supplying the modifying gas to the film; (b) a process of supplying the inert gas to the film; and (c) a process of supplying the etching gas to the film a predetermined number of times, with at least a portion of an implementation period of (a) overlapping with an implementation period of (b).

Images