Processing method, method of manufacturing semiconductor device, processing apparatus, and recording medium

Abstract

The invention relates to a processing method, a method of manufacturing a semiconductor device, a processing apparatus, and a recording medium. The present invention addresses the problem of conformally etching the surface of a recess of a substrate. The present invention relates to a method for etching at least a part of the surface of a recess by performing a cycle for a predetermined number of times including (a) and (b): (a) a step for changing the oxygen concentration in the surface of the upper part of the recess by supplying a modifying agent to a substrate having a recess having a surface comprising a substance containing oxygen by exciting the modifying agent, and (b) a step for etching at least a part of the surface of the recess by supplying the modifying agent to the substrate, and (c) a step for etching at least a part of the surface of the recess, and (b) a step of supplying an etchant to the substrate after changing the oxygen concentration in the surface of the upper portion of the recess.

Description

Technical Field

[0001] The present invention relates to a processing method, a method for manufacturing a semiconductor device, a processing apparatus, and a recording medium. Background Art

[0002] As one of the steps in the manufacturing process of a semiconductor device, a process of removing a base layer exposed on the surface of a substrate by etching is sometimes performed (for example, see Patent Documents 1 and 2).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-082774

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2022-018973 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] The present invention provides a technique for conformally etching the surface of a recessed portion of a substrate.

[0009] Means for solving problems

[0010] According to one embodiment of the present invention, there is provided a technique comprising the step of etching at least a portion of a surface of a recessed portion by performing a cycle including the following (a) and (b) a predetermined number of times:

[0011] (a) a step of exciting and supplying a modifier to a substrate having a concave portion whose surface is composed of a substance containing oxygen, thereby changing the oxygen concentration in the surface above the concave portion; and

[0012] (b) A step of supplying an etchant to the substrate after changing the oxygen concentration on the surface of the upper portion of the recess.

[0013] Effects of the Invention

[0014] According to the present invention, the surface of the recessed portion of the substrate can be conformally etched. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of a vertical processing furnace of a processing apparatus preferably used in one embodiment of the present invention, and shows a processing furnace 202 portion in a vertical cross-sectional view.

[0016] Figure 2 This is a schematic diagram of a vertical processing furnace suitable for use in one embodiment of the present invention. Figure 1The AA line cross-sectional view shows a portion of the processing furnace 202 .

[0017] Figure 3 1 is a schematic configuration diagram of a controller 121 of a processing device preferably used in one embodiment of the present invention, and is a diagram showing a control system of the controller 121 as a block diagram.

[0018] Figure 4 (a) is a partial cross-sectional enlarged view showing a surface portion of a substrate in one embodiment of the present invention having a recessed portion whose surface is composed of an oxygen-containing substance; Figure 4 (b) shows the Figure 4 A partial cross-sectional enlarged view of the surface portion of the substrate in one embodiment of the present invention after exciting and supplying the modifier starting from the state (a); Figure 4 (c) in the figure shows the Figure 4 A partial cross-sectional enlarged view of the surface portion of the substrate in one embodiment of the present invention after supplying the etchant starting from the state (b); Figure 4 (d) in the figure shows the Figure 4 A partial cross-sectional enlarged view of the surface portion of the substrate in one embodiment of the present invention after the modifier is excited and further supplied starting from the state (c); Figure 4 (e) in the figure shows the Figure 4 A partial cross-sectional enlarged view of the surface portion of the substrate in one embodiment of the present invention after further supplying the etchant from the state (d) in FIG. Figure 4 (f) in the figure shows the Figure 4 A partial cross-sectional enlarged view of the surface portion of the substrate in one embodiment of the present invention after supplying the oxidizing agent starting from the state (e) in FIG.

[0019] Description of Reference Numerals

[0020] 200 wafers (substrates) DETAILED DESCRIPTION

[0021] <First aspect of the present invention>

[0022] The following mainly refers to Figures 1 to 3 、 Figure 4 (a)~ Figure 4 (f) of the figure illustrates the first embodiment of the present invention. It should be noted that the drawings used in the following description are schematic, and the dimensional relationships and ratios of the elements shown in the drawings may not necessarily be consistent with reality. Furthermore, the dimensional relationships and ratios of the elements may not necessarily be consistent across multiple drawings.

[0023] (1) Configuration of the processing device

[0024] like Figure 1As shown, the processing furnace 202 of the processing apparatus includes a heater 207 as a temperature regulator (heating unit). Heater 207 is cylindrical and vertically mounted by being supported by a holding plate. Heater 207 also functions as an activation mechanism (excitation unit) that activates (excites) the gas using heat.

[0025] Inside the heater 207, a reaction tube 203 is arranged concentrically with the heater 207. The reaction tube 203 is made of a heat-resistant material such as quartz (SiO2) or silicon carbide (SiC) and has a cylindrical shape with a closed upper end and an open lower end. Below the reaction tube 203, a manifold 209 is arranged concentrically with the reaction tube 203. The manifold 209 is made of a metal material such as stainless steel (SUS) and has a cylindrical shape with open upper and lower ends. The upper end of the manifold 209 engages with the lower end of the reaction tube 203 to support the reaction tube 203. An O-ring 220a is provided between the manifold 209 and the reaction tube 203 as a sealing member. The reaction tube 203 is mounted vertically, similar to the heater 207. The reaction tube 203 and the manifold 209 primarily constitute a processing vessel (reaction container). A processing chamber 201 is formed in the hollow portion of the processing vessel. The processing chamber 201 is configured to accommodate a wafer 200 as a substrate. Processing of the wafer 200 is performed in the processing chamber 201 .

[0026] Within the processing chamber 201, nozzles 249a to 249c, serving as first to third supply units, are provided, respectively, extending through the sidewalls of the manifold 209. These nozzles 249a to 249c are also referred to as the first to third nozzles, respectively. These 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 these nozzles, respectively. These nozzles 249a to 249c are separate nozzles, and nozzles 249a and 249c are positioned adjacent to nozzle 249b.

[0027] Gas supply pipes 232a to 232c are provided, in order from the upstream side of the gas flow, with mass flow controllers (MFCs) 241a to 241c, serving as flow controllers (flow control units), and valves 243a to 243c, serving as on-off valves. Gas supply pipes 232d and 232f are connected to gas supply pipe 232a, downstream of valve 243a. Gas supply pipes 232e and 232g are connected to gas supply pipe 232b, downstream of valve 243b. Gas supply pipe 232h is connected to gas supply pipe 232c, downstream of valve 243c. MFCs 241d to 241h and valves 243d to 243h are provided on gas supply pipes 232d to 232h, in order from the upstream side of the gas flow. Gas supply pipes 232a to 232h are made of a metal material, such as SUS.

[0028] like Figure 2 As shown, nozzles 249a-249c are arranged in the annular space between the inner wall of the reaction tube 203 and the wafers 200, extending upward from the lower portion of the inner wall of the reaction tube 203 along the upper portion toward the direction in which the wafers 200 are arranged, extending along the wafer arrangement area. Specifically, nozzles 249a-249c are arranged along the wafer arrangement area, in areas lateral to and horizontally surrounding the wafer arrangement area where the wafers 200 are arranged. In a plan view, nozzle 249b is arranged so as to be aligned with exhaust port 231a (described later) across the center of the wafer 200 within the processing chamber 201. Nozzles 249a and 249c are arranged along the inner wall of the reaction tube 203 (the outer periphery of the wafers 200) to sandwich a straight line L passing through the centers of nozzle 249b and exhaust port 231a. Line L also passes through the centers of nozzle 249b and wafer 200. That is, nozzle 249c may be positioned on the opposite side of nozzle 249a, with line L interposed therebetween. Nozzles 249a and 249c are arranged symmetrically with line L as the axis of symmetry. Gas supply holes 250a to 250c for supplying gas are provided on the side surfaces of nozzles 249a to 249c, respectively. Gas supply holes 250a to 250c are each opened so as to face exhaust port 231a when viewed from above, enabling gas to be supplied to wafer 200. A plurality of gas supply holes 250a to 250c are provided from the bottom to the top of reaction tube 203.

[0029] A reducing agent serving as a modifier is supplied from the gas supply pipe 232 a through the MFC 241 a , the valve 243 a , and the nozzle 249 a into the processing chamber 201 .

[0030] The etchant is supplied from the gas supply pipe 232b through the MFC 241b, the valve 243b, and the nozzle 249b into the processing chamber 201. The etchant supplied from the gas supply pipe 232b is also referred to as a first substance.

[0031] The etchant is supplied from the gas supply pipe 232c through the MFC 241c, the valve 243c, and the nozzle 249c into the processing chamber 201. The etchant supplied from the gas supply pipe 232c is also referred to as a second substance.

[0032] An oxidizing agent serving as a modifier is supplied from the gas supply pipe 232 d into the processing chamber 201 via the MFC 241 d , the valve 243 d , the gas supply pipe 232 a , and the nozzle 249 a .

[0033] The catalyst is supplied from the gas supply pipe 232e into the processing chamber 201 via the MFC 241e, the valve 243e, the gas supply pipe 232b, and the nozzle 249b.

[0034] Inert gas is supplied from gas supply pipes 232f to 232h through MFCs 241f to 241h, valves 243f to 243h, gas supply pipes 232a to 232c, and nozzles 249a to 249c into the processing chamber 201. The inert gas functions as a purge gas, carrier gas, or dilution gas.

[0035] A remote plasma unit (hereinafter referred to as RPU) 300 is provided on the downstream side of the connection portion of the gas supply pipe 232a with the gas supply pipe 232f, serving as a plasma excitation portion (plasma generation portion) for exciting the gas into a plasma state. Exciting the gas into a plasma state is also referred to as exciting the gas plasma. The RPU 300 applies high frequency (RF) power, thereby plasmatizing the gas inside the RPU 300 and exciting it, that is, exciting the gas into a plasma state. As a plasma generation method, a capacitively coupled plasma (CCP) method or an inductively coupled plasma (ICP) method can be used. The RPU 300 is configured to excite the modifier and inert gas supplied from the gas supply pipes 232a, 232d, and 232f into a plasma state and supply them into the processing chamber 201. The RPU 300 is also referred to as an excitation portion.

[0036] The reducing agent supply system is mainly composed of the gas supply pipe 232a, MFC241a, and valve 243a. The etching agent (first substance) supply system is mainly composed of the gas supply pipe 232b, MFC241b, and valve 243b. The etching agent (second substance) supply system is mainly composed of the gas supply pipe 232c, MFC241c, and valve 243c. The oxidizing agent supply system is mainly composed of the gas supply pipe 232d, MFC241d, and valve 243d. The catalyst supply system is mainly composed of the gas supply pipe 232e, MFC241e, and valve 243e. The inert gas supply system is mainly composed of the gas supply pipes 232f to 232h, MFC241f to 241h, and valves 243f to 243h. Each or all of the reducing agent supply system and the oxidizing agent supply system is also referred to as the modifier supply system. The RPU 300 may also be included in the modifier supply system.

[0037] Any or all of the various supply systems described above may be configured as an integrated supply system 248 in which valves 243a to 243h, MFCs 241a to 241h, and the like are integrated. Integrated supply system 248 is connected to each of gas supply pipes 232a to 232h. The supply of various substances (gases) into gas supply pipes 232a to 232h, namely, the opening and closing of valves 243a to 243h, and the flow rate adjustment by MFCs 241a to 241h, are controlled by controller 121, described later. Integrated supply system 248 is configured as a single or split integrated unit, and is attachable to and detachable from gas supply pipes 232a to 232h, etc., as a unit. Maintenance, replacement, and expansion of integrated supply system 248 can be performed as a unit.

[0038] An exhaust port 231a is provided below the side wall of the reaction tube 203 to exhaust the atmosphere in the processing chamber 201. Figure 2 As shown, the exhaust port 231a is positioned opposite (facing) the nozzles 249a-249c (gas supply holes 250a-250c) across the wafer 200 when viewed from above. The exhaust port 231a can also be arranged along the sidewall of the reaction tube 203 from the bottom to the top, that is, 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, which serves as a pressure detector (pressure detection unit) for detecting the pressure within the processing chamber 201, and an APC (Auto Pressure Controller) valve 244, which serves as a pressure regulator (pressure regulation unit). The APC valve 244 is configured to open and close the valve while the vacuum pump 246 is in operation, thereby enabling vacuum exhaust and stopping of the processing chamber 201. Furthermore, while the vacuum pump 246 is in operation, the pressure within the processing chamber 201 can be regulated by adjusting the valve opening based on pressure information detected by the pressure sensor 245. The exhaust system mainly comprises the exhaust pipe 231, the APC valve 244, and the pressure sensor 245. A vacuum pump 246 may also be included in the exhaust system.

[0039] Below the manifold 209, a sealing cover 219 is provided as a furnace port cover that can airtightly seal the lower end opening of the manifold 209. The sealing cover 219 is made of a metal material such as SUS and is formed into a disc shape. An O-ring 220b is provided on the upper surface of the sealing cover 219 as a sealing member that abuts the lower end of the manifold 209. Below the sealing cover 219, a rotating mechanism 267 is provided for rotating the wafer boat 217 described later. The rotating shaft 255 of the rotating mechanism 267 passes through the sealing cover 219 and is connected to the wafer boat 217. The rotating mechanism 267 is configured to rotate the wafer 200 by rotating the wafer boat 217. The sealing cover 219 is configured to be raised and lowered in the vertical direction by the wafer boat elevator 115 as an elevating mechanism provided outside the reaction tube 203. The boat elevator 115 serves as a transport device (transport mechanism) that transports the wafers 200 into and out of the processing chamber 201 by raising and lowering the seal cap 219 .

[0040] A gate 219s, serving as a furnace port cover, is provided below the manifold 209. When the sealing cover 219 is lowered and the wafer boat 217 is removed from the processing chamber 201, it hermetically seals the lower opening of the manifold 209. Gate 219s is formed of a metal material, such as SUS, and is disc-shaped. An O-ring 220c, serving as a sealing member, is provided on the upper surface of gate 219s, contacting the lower end of the manifold 209. The opening and closing movements (lifting, rotation, etc.) of gate 219s are controlled by a gate opening and closing mechanism 115s.

[0041] The wafer boat 217, serving as a substrate support, is constructed to support multiple wafers 200, for example, 25 to 200, arranged in a horizontal position with their centers aligned vertically in multiple layers, i.e., arranged at intervals. The wafer boat 217 is made of a heat-resistant material such as quartz or SiC. Heat shields 218, also made of a heat-resistant material such as quartz or SiC, are supported in multiple layers at the bottom of the wafer boat 217.

[0042] A temperature sensor 263 is provided within the reaction tube 203 as a temperature detector. By adjusting the power supply to the heater 207 based on the temperature information detected by the temperature sensor 263, the temperature within the processing chamber 201 is adjusted to a desired temperature distribution. The temperature sensor 263 is provided along the inner wall of the reaction tube 203.

[0043] like Figure 3As shown, the controller 121 as a control unit (control unit) is configured as a computer having 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. In addition, an external storage device 123 can be connected to the controller 121. It should be noted that the processing device can be configured to have one control unit or multiple control units. That is, the control for performing the processing sequence described below can be performed using one control unit or multiple control units. In addition, the multiple control units can be configured as a control system interconnected by a wired or wireless communication network, or the control system as a whole can be used to perform the control for performing the processing sequence described below. When the term "control unit" is used in this specification, it includes not only one control unit but also a plurality of control units and a control system composed of a plurality of control units.

[0044] The storage device 121c is composed of, for example, a flash memory, an HDD (Hard Disk Drive), an SSD (Solid State Drive), etc. The control program for controlling the action of the processing device, the process procedure that records the steps and conditions of the substrate processing described later, etc. are recorded and stored in a readable manner in the storage device 121c. The process procedure is a combination of the controller 121 to enable the processing device to perform the various steps in the substrate processing (etching processing) described later, and to obtain a predetermined result, and functions as a program. Hereinafter, the process procedure, control program, etc. are also collectively referred to as a program. In addition, the process procedure is also referred to as a process. When the term program is used in this specification, sometimes only the process is included alone, sometimes only the control program is included alone, or sometimes both are included. RAM121b is configured as a memory area (work area) that temporarily holds the programs, data, etc. read by CPU121a.

[0045] The I / O port 121d is connected to the above-mentioned MFCs 241a to 241h, valves 243a to 243h, pressure sensor 245, APC valve 244, vacuum pump 246, temperature sensor 263, heater 207, rotation mechanism 267, boat elevator 115, gate opening and closing mechanism 115s, RPU 300, etc.

[0046] 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. In accordance with the contents of the read recipe, the CPU 121a is configured to control the flow rate adjustment of various substances (gases) by the MFCs 241a to 241h, the opening and closing of the valves 243a to 243h, the opening and closing of the APC valve 244, the pressure adjustment by the pressure sensor 245 and the APC valve 244, the start and stop of the vacuum pump 246, the temperature adjustment of the heater 207 by the temperature sensor 263, the rotation and rotation speed adjustment of the wafer boat 217 by the rotation mechanism 267, the lifting and lowering of the wafer boat 217 by the wafer elevator 115, the opening and closing of the gate 219s by the gate opening and closing mechanism 115s, and the plasma excitation of the gas by the RPU 300.

[0047] The controller 121 can be constructed 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 disk such as an HDD, an optical disk such as a CD, an optical disk such as an MO, a semiconductor memory such as a USB memory, an SSD, etc. The storage device 121c and the external storage device 123 constitute a recording medium that can be read by a computer. Hereinafter, they will also be collectively referred to as recording media. When the term recording medium is used in this specification, sometimes only the storage device 121c is included, sometimes only the external storage device 123 is included, or sometimes both are included. It should be noted that, instead of using the external storage device 123, a communication unit such as the Internet or a dedicated line can be used to provide the program to the computer.

[0048] (2) Processing

[0049] As one step of a manufacturing process (manufacturing method) of a semiconductor device using the above-mentioned processing apparatus, a method (processing method) for processing a substrate, that is, an example of a processing sequence for etching at least a portion of a surface of a recessed portion of a wafer 200 as a substrate, is described. Figure 4 (a)~ Figure 4 (f) in the following description. In the following description, the operations of the various components constituting the processing device are controlled by the controller 121. It should be noted that the processing device is also referred to as a substrate processing device, an etching processing device, or an etching device. In addition, the processing method is also referred to as a substrate processing method, an etching processing method, or an etching method.

[0050] In the processing sequence of this embodiment, a cycle including the following steps (a) and (b) is performed a predetermined number of times (n times, where n is an integer of 1 or 2 or greater), thereby etching at least a portion of the surface of the recessed portion:

[0051] (a) step A of exciting and supplying a modifier to a wafer 200 having a recessed portion whose surface is made of a substance containing oxygen, thereby changing the oxygen concentration in the upper surface of the recessed portion; and

[0052] (b) Step B of supplying an etchant to the wafer 200 after changing the oxygen concentration on the surface of the upper portion of the recess. The above series of processes is also referred to as etching process.

[0053] The following examples describe a case where, in step A, a modifier containing a reducing agent is used to make the oxygen concentration at the surface of the upper portion of the recess different from the oxygen concentration at the surface of the portion other than the upper portion of the recess. Specifically, the case where the oxygen concentration at the surface of the upper portion of the recess is lowered compared to the oxygen concentration at the surface of the portion other than the upper portion of the recess is described. It should be noted that the portion other than the upper portion of the recess includes at least one of the central portion, lower portion, or bottom portion of the recess. Hereinafter, the portion other than the upper portion of the recess will also be referred to as the lower side of the recess.

[0054] In the following example, the case of further performing step C of oxidizing the surface of the etched recessed portion to make the oxygen concentration on the surface of the recessed portion uniform is described. However, if it is not necessary to make the oxygen concentration on the surface of the etched recessed portion uniform, step C can be omitted.

[0055] In this specification, for convenience, the above-mentioned processing sequence may be shown as follows. It should be noted that the same expressions as above may also be used in the following description of modified examples.

[0056] (modification → etching) × n → oxidation

[0057] (modification → etching) × n

[0058] The term "wafer" as used in this specification may refer to the wafer itself or to a laminate of a wafer and a predetermined layer or film formed on its surface. The term "surface of a wafer" as used in this specification may refer to the surface of the wafer itself or to the surface of a predetermined layer or film formed on the wafer. When "etching the surface of a wafer" is used in this specification, this may refer to etching the surface of the wafer itself or to etching a layer or film formed on the wafer. The term "substrate" used in this specification is also synonymous with the term "wafer."

[0059] As used in this specification, the term "agent" encompasses at least one of a gaseous substance and a liquid substance. Liquid substances include mist-like substances. That is, each of a modifier, an etchant, an oxidant, and a catalyst may comprise a gaseous substance, a liquid substance such as a mist-like substance, or both.

[0060] (Wafer filling and wafer boat loading)

[0061] After a plurality of wafers 200 are loaded into the wafer boat 217 (wafer filling), the gate 219s is moved by the gate opening and closing mechanism 115s, and the lower end opening of the manifold 209 is opened (gate opening). Figure 1 As shown, the wafer boat 217 supporting multiple wafers 200 is lifted by the boat elevator 115 and loaded into the processing chamber 201 (boat loading). In this state, the seal cap 219 seals the lower end of the manifold 209 via the O-ring 220b. Thus, the wafers 200 are prepared in the processing chamber 201.

[0062] The wafers 200 loaded in the wafer boat 217 are as follows: Figure 4 As shown in (a) in FIG, the surface of the concave portion has a concave portion such as a hole or a groove. The surface of the concave portion is composed of a substance containing oxygen (oxygen-containing substance), that is, an oxide. The surface of the concave portion can be composed of a substance containing silicon (Si) and oxygen (O), that is, a silicon oxide. For example, the surface of the concave portion can be composed of a silicon oxide film such as a silicon oxide film (SiO film), a silicon oxynitride film (SiON film), a silicon oxycarbonitride film (SiOCN film), or a silicon oxycarbide film (SiOC film). In addition, the surface of the concave portion can also be composed of a silicon film (Si film) having a natural oxide film formed on the surface, a silicon nitride film (SiN film), a silicon carbonitride film (SiCN film), a silicon carbide film (SiC film), a silicon boron nitride film (SiBN film), a silicon boron carbon nitride film (SiBCN film), a SiON film, a SiOCN film, or a SiOC film, that is, a Si-containing film having a natural oxide film formed on the surface. At least a portion of the surface of the concave portion becomes the target of the etching process described later.

[0063] (Pressure regulation and temperature regulation)

[0064] After the wafer boat is loaded, vacuum pump 246 performs vacuum evacuation (decompression evacuation) to reduce the pressure (vacuum level) within processing chamber 201, i.e., the space containing wafers 200. The pressure within processing chamber 201 is measured by pressure sensor 245, and feedback control of APC valve 244 is performed based on this measured pressure information. Heater 207 heats the wafers 200 within processing chamber 201 to the desired processing temperature. Feedback control of the power supply to heater 207 is performed based on temperature information detected by temperature sensor 263 to achieve the desired temperature distribution within processing chamber 201. Rotation of wafer 200 by rotation mechanism 267 is also initiated. Exhausting processing chamber 201, heating wafers 200, and rotating them continue for at least the duration until processing of wafers 200 is completed.

[0065] (Step A)

[0066] Thereafter, a modifier including a reducing agent is excited and supplied to the wafer 200 having a recessed portion whose surface is made of an oxygen-containing substance.

[0067] Specifically, valve 243a is opened, and a modifier (reducing agent) flows into the gas supply pipe 232a. The modifier is flow-regulated by MFC241a, and after being excited into a plasma state by RPU300, it is supplied into the processing chamber 201 through nozzle 249a and exhausted from exhaust port 231a. At this time, the modifier excited into a plasma state is supplied to the wafer 200 from the side of the wafer 200 (modifier supply). Thus, excited species generated by exciting the modifier, that is, excited species (active species) generated by exciting the modifier into a plasma state, are supplied to the wafer 200. At this time, valves 243f~243h can also be opened to supply inactive gas into the processing chamber 201 through each of nozzles 249a~249c.

[0068] Under the processing conditions described below, the modifier is excited into a plasma state and supplied to the wafer 200, so that the excited species generated by the modifier being excited into a plasma state react with the surface of the upper portion of the recess, as shown in FIG. Figure 4 As shown in (b), the oxygen concentration (oxygen ratio, oxygen content) in the upper surface of the recess can be changed. The portion of the recess surface where the oxygen concentration changes due to the supply of the excited modifier is also referred to as a modified portion.

[0069] It should be noted that, under the processing conditions described below, the modifier is excited and supplied to the wafer 200, so that at least a portion of the excited species supplied to the wafer 200 can be consumed and inactivated by reacting with the surface of the upper portion of the recess. As a result, the amount of excited species supplied per unit surface area can be reduced in portions other than the upper portion of the recess, that is, in at least any one of the central portion, lower portion, and bottom portion of the recess, compared to the upper portion of the recess. Thus, in portions other than the upper portion of the recess, the reaction of the excited species with the surface is suppressed compared to the upper portion of the recess, and the change in the oxygen concentration on the surface can be reduced. As a result, in step A, the oxygen concentration on the surface of the upper portion of the recess can be made different from the oxygen concentration on the surface of portions other than the upper portion of the recess. This phenomenon is particularly pronounced when the modifier is excited and supplied to the wafer 200 to form a plasma state, that is, when excited species (active species) generated by exciting the modifier into a plasma state are supplied.

[0070] In this method, under the processing conditions described below, a reducing agent serving as a modifier is excited to a plasma state and supplied to the wafer 200. This allows a surface reduction reaction based on the excited species to proceed in the upper portion of the recess, thereby reducing the surface oxygen concentration. Furthermore, in portions other than the upper portion of the recess, the supply of excited species per unit area is reduced, suppressing the surface reduction reaction based on the excited species and minimizing the reduction in surface oxygen concentration. As a result, in step A, the surface oxygen concentration in the upper portion of the recess can be reduced compared to the surface oxygen concentration in portions other than the upper portion of the recess.

[0071] As the treatment conditions when the modifier (reducing agent) is excited into a plasma state and supplied in step A, the following can be exemplified:

[0072] Treatment temperature: room temperature (25°C) to 400°C, preferably 50 to 250°C

[0073] Processing pressure: 1-10000Pa, preferably 50-1000Pa

[0074] Processing time: 1 to 600 seconds, preferably 5 to 300 seconds

[0075] Modifier supply flow rate: 0.01~10slm, preferably 0.1~5slm

[0076] Inert gas supply flow rate (per gas supply pipe): 0 to 20 slm

[0077] RF power: 1-10000W, preferably 100-5000W

[0078] RF frequency: 13.5MHz or 27MHz.

[0079] It should be noted that the expression of a numerical range such as "25 to 400°C" in this specification means that the lower limit and the upper limit are included in the range. Therefore, for example, the so-called "25 to 400°C" means "above 25°C and below 400°C". The same applies to other numerical ranges. In addition, the so-called processing temperature in this specification refers to the temperature of the wafer 200 or the temperature in the processing chamber 201, and the so-called processing pressure refers to the pressure in the processing chamber 201. In addition, the so-called processing time refers to the time during which the processing continues. In addition, when the supply flow rate includes 0slm, the so-called 0slm refers to the case where the substance (gas) is not supplied. In addition, the so-called RF power refers to the high-frequency power applied to the electrode possessed by the RPU300 when the modifier plasma is excited, and the so-called RF frequency refers to the frequency in the above-mentioned RF power. This is also the same in the following description.

[0080] After the oxygen concentration on the surface of the upper portion of the recess is changed (in this embodiment, it is reduced), valve 243a is closed to stop the supply of the modifier 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, valves 243f to 243h are opened to supply an inert gas into the processing chamber 201 through nozzles 249a to 249c. The inert gas supplied from nozzles 249a to 249c acts as a purge gas, thereby purging (purging) the interior of the processing chamber 201.

[0081] As treatment conditions for purging in step A, the following can be exemplified:

[0082] Processing pressure: 1~30Pa

[0083] Processing time: 1 to 120 seconds, preferably 1 to 60 seconds

[0084] Inert gas supply flow rate (per gas supply pipe): 0.5~20slm

[0085] In addition, the treatment temperature when performing purging in this step is preferably set to the same temperature as the treatment temperature when supplying the modifier.

[0086] As a modifier (reducing agent), a hydrogen-containing gas such as hydrogen (H2) gas or a deuterium-containing gas such as deuterium (D2) gas can be used. As a modifier, one or more of the above-mentioned gases can be used. It should be noted that the process of exciting a hydrogen-containing gas to a plasma state and supplying it to the wafer 200 is also referred to as a hydrogen-containing plasma process, and the active species (H2*, H*, etc.) generated at this time are also referred to as hydrogen-containing active species (hydrogen-containing free radicals). In addition, the process of exciting a deuterium-containing gas to a plasma state and supplying it to the wafer 200 is also referred to as a deuterium-containing plasma process, and the active species (D2*, D*, etc.) generated at this time are also referred to as deuterium-containing active species (deuterium-containing free radicals).

[0087] As the inert gas, rare gases such as nitrogen (N2), argon (Ar), helium (He), neon (Ne), and xenon (Xe) can be used. As the inert gas, one or more of these can be used. This also applies to the steps described below.

[0088] (Step B)

[0089] After step A is completed, an etchant is supplied to the wafer 200 so that the oxygen concentration in the surface of the upper portion of the recess is changed (reduced in this embodiment).

[0090] Specifically, valve 243b is opened to allow the etchant to flow into gas supply pipe 232b. The etchant is flow-regulated by MFC 241b, supplied into processing chamber 201 via nozzle 249b, and exhausted from exhaust port 231a. At this point, the etchant is supplied to wafer 200 from the side (etchant supply). Alternatively, valves 243f to 243h may be opened to allow inert gas to be supplied into processing chamber 201 via nozzles 249a to 249c, respectively.

[0091] By supplying an etchant to the wafer 200 under the processing conditions described below, Figure 4 As shown in (c) in FIG. 1 , at least a portion of the surface of the recessed portion can be etched.

[0092] Here, at least a portion of the etchant supplied to the wafer 200 is consumed by the etching reaction on the surface of the upper portion of the recess.

[0093] When step B is performed instead of step A, the amount of etchant supplied per unit surface area tends to be reduced in portions other than the upper portion of the recess, that is, in at least any of the center, lower portion, and bottom portion of the recess, compared to the upper portion of the recess. In this case, the etching rate on the surface of the upper portion of the recess tends to be higher than the etching rate on the surfaces of portions other than the upper portion of the recess. In other words, the surface of the upper portion of the recess is more easily etched than the surface of the lower portion of the recess, making it difficult to etch the surface of the recess conformally.

[0094] In contrast, in this method, step A is performed before step B. Thus, the oxygen concentration in the surface of the upper portion of the concave portion to be etched can be made different from the oxygen concentration in the surface of the other portions other than the upper portion of the concave portion. Specifically, it is possible to set the state in which the oxygen concentration in the surface of the upper portion of the concave portion to be etched is lower than the oxygen concentration in the surface of the other portions other than the upper portion of the concave portion. Then, in step B, the substance used as the etchant, the processing steps, and the processing conditions are appropriately selected to form a state in which objects with high oxygen concentrations are easily etched and objects with low oxygen concentrations are not easily etched (to exert the prescribed etching selectivity). Thus, when etching the surface of the concave portion, the reduction in the etching rate on the surface of the other portions other than the upper portion of the concave portion can be suppressed, and the etching rate on the surface of the upper portion of the concave portion can be selectively reduced. That is, the etching rate on the surface of the upper portion of the concave portion can be adjusted in a direction close to the etching rate on the surface of the other portions other than the upper portion of the concave portion.

[0095] As a result, in this method, the etching rate of the upper surface of the concave portion can be reduced relative to the lower surface of the concave portion, and the tendency of the upper surface of the concave portion to be easily etched relative to the lower surface of the concave portion can be offset. As a result, the etching amount of the surface of the concave portion can be made uniform, such as Figure 4 As shown in (c) in FIG. 1 , the surface of the recessed portion can be conformally etched.

[0096] It should be noted that in this method,

[0097] The ratio of the etching rate on the upper surface of the recessed portion to the etching rate on the lower surface of the recessed portion caused by the etchant when step A is not performed is ERRA.

[0098] When the ratio of the etching rate on the upper surface of the recessed portion to the etching rate on the lower surface of the recessed portion caused by the etchant in the case of performing step A is ERRB,

[0099] The ratio of ERRB to ERRA (ERRB / ERRA) can be set to 0.01 or more and less than 1, preferably 0.02 or more and 0.9 or less, and more preferably 0.05 or more and 0.8 or less.

[0100] When performing step B, the entire modified portion may be removed. In addition, if Figure 4 As shown in (c) in FIG. 1 , a portion of the modified portion may remain. That is, etching may be stopped while the oxygen concentration in the surface of the upper portion of the recess is equal to the oxygen concentration in the surface of the portion other than the upper portion of the recess. Alternatively, etching may be stopped while the oxygen concentration in the surface of the upper portion of the recess is kept different from the oxygen concentration in the surface of the portion other than the upper portion of the recess (in this embodiment, while the oxygen concentration in the surface of the upper portion of the recess is kept low).

[0101] As the processing conditions when supplying the etching agent in step B, the following can be exemplified:

[0102] Treatment temperature: room temperature (25°C) to 400°C, preferably 50 to 250°C

[0103] Processing pressure: 1~13332Pa, preferably 1~1333Pa

[0104] Treatment time: 1 second to 120 minutes, preferably 1 minute to 60 minutes

[0105] Etchant supply flow rate: 0.001~2slm

[0106] Inert gas supply flow rate (per gas supply pipe): 0 to 20 slm

[0107] After etching of at least a portion of the surface of the recessed portion is completed, valve 243b is closed to stop the supply of the etchant into the processing chamber 201. Then, gaseous substances and the like remaining in the processing chamber 201 are removed (purged) from the processing chamber 201 through the same processing steps and processing conditions as those used for the purging in step A. It should be noted that the processing temperature during the purging in this step is preferably the same as the processing temperature during the supply of the etchant.

[0108] As an etchant, a substance containing fluorine (F), i.e., a fluorine-based substance, can be used. For example, a fluorine-containing gas can be used. As a fluorine-containing gas, for example, fluorine (F2) gas, hydrogen fluoride (HF) gas, chlorine trifluoride (ClF3) gas, chlorine fluoride (ClF) gas, nitrogen fluoride (NF3) gas, nitrosyl fluoride (FNO) gas, a fluorine-containing gas, a hydrogen and fluorine-containing gas, a chlorine and fluorine-containing gas, a nitrogen and fluorine-containing gas, a fluorine-containing, nitrogen and oxygen-containing gas, etc. can be used. In this way, as an etchant, for example, a fluorine-containing substance, a hydrogen and fluorine-containing substance, a chlorine and fluorine-containing substance, a nitrogen and fluorine-containing substance, a fluorine-containing, nitrogen and oxygen-containing substance, etc. can be used. That is, as an etchant, for example, a halogen monomer, a hydrogen halide, an interhalogen compound, a nitrogen halide, a nitrosyl halide, etc. can be used. As an etchant, one or more of these can be used.

[0109] (Specified number of implementations)

[0110] By performing a cycle including the above-mentioned step A and step B, i.e., performing a cycle in which each step is performed sequentially and non-simultaneously for a predetermined number of times (n times, where n is an integer greater than 1 or 2), it is possible to perform an etching process in which the surface of the recess is conformally etched by a predetermined amount. The above-mentioned cycle is preferably repeated a plurality of times. That is, it is preferred that the thickness of the surface of the recess etched in each cycle is made thinner than the desired etching thickness (predetermined amount) until the etching thickness of the surface of the recess becomes the desired thickness (depth), and the above-mentioned cycle is repeated a plurality of times. In this case, in step A of the first cycle, as Figure 4 As shown in (b), a part of the surface of the concave portion is modified, and in step B of the first cycle, as shown in Figure 4 As shown in (c) in FIG. 1 , a portion of the surface of the recess is etched. In addition, in step A after the second cycle, as shown in FIG. Figure 4 As shown in (d), a part of the surface of the etched concave portion is further modified, and in step B after the second cycle, as shown in Figure 4 As shown in (e), a portion of the surface of the etched recessed portion is further etched. By repeating the above cycle multiple times, all of the oxygen-containing species constituting the surface of the recessed portion can be removed.

[0111] (Step C)

[0112] As described above, the oxygen concentration in the upper surface of the recessed portion, which has been changed in step A, is maintained even after step B. In this case, after the etching process (after the aforementioned cycle has been performed a predetermined number of times), the oxygen concentration in the upper surface of the recessed portion may differ from the oxygen concentration in the surfaces of other portions of the recessed portion. Therefore, in this embodiment, step C of supplying an oxidizing agent to wafer 200 is performed after the etching process. The following describes the case where a catalyst is supplied to wafer 200 along with the oxidizing agent in step C. It should be noted that the supply of the catalyst in step C can also be omitted.

[0113] Specifically, valves 243d and 243e are opened to allow an oxidant and catalyst to flow into gas supply pipes 232d and 232e, respectively. The oxidant and catalyst are flow-regulated by MFCs 241d and 241e, respectively, and supplied into processing chamber 201 via gas supply pipes 232a and 232b and nozzles 249a and 249b. The oxidant and catalyst are mixed within processing chamber 201 and exhausted from exhaust port 231a. At this point, the oxidant and catalyst are supplied to wafer 200 from the side (oxidant + catalyst supply). Alternatively, valves 243f to 243h can be opened to allow an inert gas to be supplied into processing chamber 201 via nozzles 249a to 249c.

[0114] Under the processing conditions described below, an oxidant is supplied to the wafer 200, thereby Figure 4 As shown in (f) in FIG. , the surface of the recessed portion after etching can be oxidized. This makes it possible to make the oxygen concentration (oxygen ratio, oxygen content) on the surface of the recessed portion uniform, and to make the oxygen concentration on the surface of the upper portion of the recessed portion equal to the oxygen concentration on the surface of the other portions of the recessed portion. The portion of the recessed portion surface that is oxidized by the supply of the oxidant, i.e., the portion with a uniform oxygen concentration, is also referred to as an oxidized portion.

[0115] As treatment conditions when supplying the oxidizing agent in step C, the following can be exemplified:

[0116] Treatment temperature: room temperature (25°C) to 400°C, preferably 50 to 250°C

[0117] Processing pressure: 1-10000Pa, preferably 50-1000Pa

[0118] Processing time: 1 to 600 seconds, preferably 5 to 300 seconds

[0119] Oxidant supply flow rate: 0.01 to 10 slm, preferably 0.1 to 5 slm

[0120] Catalyst supply flow rate: 0-10slm, preferably 0-5slm

[0121] Inert gas supply flow rate (per gas supply pipe): 0 to 20 slm

[0122] After the oxygen concentration on the surface of the recess is made uniform, valves 243d and 243e are closed to stop the supply of the oxidant and catalyst into the processing chamber 201. Then, the gaseous substances and the like remaining in the processing chamber 201 are removed (purged) from the processing chamber 201 by the same processing steps and processing conditions as those in step A. It should be noted that the processing temperature during the purge in this step is preferably the same as the processing temperature during the supply of the oxidant.

[0123] As oxidant, oxygen (O2) gas, ozone (O3) gas, O2 gas+H2 gas, O2 gas+D2 gas, O3 gas+H2 gas, O3 gas+D2 gas, hydrogen peroxide (H2O2) gas, water vapor (H2O gas), nitrous oxide (N2O) gas, nitric oxide (NO) gas, nitrogen dioxide (NO2) gas, carbon dioxide (CO2) gas, carbon monoxide (CO) gas and other oxygen-containing gases can be used. As oxidant, more than one of them can be used. Here, the recording of two kinds of gases such as "O2 gas+H2 gas" refers to a mixed gas of O2 gas and H2 gas. When supplying a mixed gas, the two kinds of gases can be mixed (pre-mixed) in a supply pipe and then supplied to the processing chamber 201. Alternatively, the two kinds of gases can be supplied to the processing chamber 201 by different supply pipes respectively and mixed (post-mixed) in the processing chamber 201.

[0124] As a catalyst, for example, an amine gas (amine substance) containing carbon (C), nitrogen (N) and hydrogen (H) can be used. As the amine gas (amine substance), a chain amine gas (chain amine substance) or a cyclic amine gas (cyclic amine substance) can be used. As a catalyst, for example, chain amines such as triethylamine ((C2H5)3N), diethylamine ((C2H5)2NH), monoethylamine ((C2H5)NH2), trimethylamine ((CH3)3N), dimethylamine ((CH3)2NH), and monomethylamine ((CH3)NH2) can be used. In addition, as a catalyst, for example, aminopyridine (C5H6N2), pyridine (C5H5N), picoline (C6H7N), lutidine (C7H9N), pyrimidine (C4H4N2), quinoline (C9H7N), piperazine (C4H 10 N2), piperidine (C5H 11 As a catalyst, one or more of these can be used.

[0125] Note that, as described above, when it is not necessary to make the oxygen concentration in the surface of the recessed portion uniform after the etching process, step C can be omitted.

[0126] (Post-purge and atmospheric pressure recovery)

[0127] After step C is completed, an inert gas is supplied from each of nozzles 249a to 249c into the processing chamber 201 as a purge gas and exhausted from exhaust port 231a. Thus, the processing chamber 201 is purged, and the gas, reaction byproducts, etc. remaining in the processing chamber 201 are removed from the processing chamber 201 (post-purge). Afterwards, 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 restored to normal pressure (atmospheric pressure recovery).

[0128] (Wafer boat unloading and wafer removal)

[0129] The boat elevator 115 then lowers the seal cap 219, opening the lower end of the manifold 209. The processed wafers 200, supported by the boat 217, are then unloaded from the lower end of the manifold 209 to the exterior of the reaction tube 203 (boat unloading). After the boat is unloaded, the gate 219s is moved, sealing the lower end of the manifold 209 with the gate 219s via the O-ring 220c (gate closing). After the processed wafers 200 are unloaded from the boat 217 (wafer removal).

[0130] Steps A, B, and C are preferably performed in the same processing chamber (in-situ). If a series of processes are performed in-situ, the wafer 200 is not exposed to the atmosphere during processing, and the wafer 200 can be processed continuously while being placed under vacuum, thereby achieving stable processing.

[0131] (3) Effects of this method

[0132] According to this embodiment, one or more of the following effects can be obtained.

[0133] (a) By performing a cycle including steps A and B a predetermined number of times, when etching the surface of a recessed portion of a substrate, the etching rate of the upper surface of the recessed portion can be reduced relative to the lower surface of the recessed portion, thereby offsetting the tendency of the upper surface of the recessed portion to be etched more easily than the lower surface of the recessed portion. This makes it possible to uniformize the amount of etching on the surface of the recessed portion, resulting in conformal etching of the surface of the recessed portion. In other words, the surface of the recessed portion can be etched with high conformality.

[0134] (b) In step A, excited species generated by exciting the modifier are supplied to the substrate, thereby deactivating the excited species generated by exciting the modifier in the upper portion of the recess, and selectively changing the oxygen concentration in the surface of the upper portion of the recess.

[0135] In step A, when excited species are supplied to the substrate to excite the modifier into a plasma state, active species can be generated as excited species, the degree of deactivation of the excited species in the upper part of the recess can be effectively increased, and the operation of selectively changing the oxygen concentration in the surface of the upper part of the recess can be effectively performed.

[0136] (c) Since the modifier contains a reducing agent, the above-mentioned action can be effectively produced, and the operation of selectively changing the oxygen concentration in the surface of the upper portion of the recessed portion can be effectively performed.

[0137] In addition, by making the modifier include at least one of a hydrogen-containing gas and a deuterium-containing gas, that is, by performing at least one of a hydrogen-containing plasma treatment and a deuterium plasma treatment in step A, the above-mentioned effect can be produced more effectively, and the operation of selectively changing the oxygen concentration in the surface of the upper part of the recess can be performed more effectively.

[0138] (d) In step A, by making the oxygen concentration in the surface of the upper portion of the recess different from the oxygen concentration in the surfaces of the other portions of the recess, the etching rate of the surface of the upper portion of the recess can be reduced relative to the surfaces of the other portions of the recess, thereby offsetting the tendency of the upper portion of the recess to be easily etched relative to the surfaces of the other portions of the recess. This effectively makes the etching amount of the surface of the recess uniform, and as a result, the surface of the recess can be efficiently and conformally etched.

[0139] (e) By making the surface of the recessed portion comprise the above-mentioned oxide, the above-mentioned effect can be effectively produced.

[0140] (f) The above-mentioned effect can be effectively produced by making the etchant contain fluorine. When the etchant contains fluorine and hydrogen, the above-mentioned effect can be more effectively produced.

[0141] (g) By setting ERRB / ERRA to 0.01 or more and less than 1, the surface of the recessed portion can be conformally etched.

[0142] Here, if ERRB / ERRA is set to less than 0.01, the effect of reducing the etching rate of the surface on the upper side of the recess relative to the surface on the lower side of the recess becomes excessive, and the surface on the lower side of the recess is excessively etched relative to the surface on the upper side of the recess, and the surface of the recess may not be etched conformally. As in this embodiment, by setting ERRB / ERRA to 0.01 or greater, the effect of reducing the etching rate of the surface on the upper side of the recess relative to the surface on the lower side of the recess can be optimized, and the surface of the recess can be etched conformally. This effect can be enhanced by setting ERRB / ERRA to 0.02 or greater, and further enhanced by setting ERRB / ERRA to 0.05 or greater.

[0143] Furthermore, if ERRB / ERRA is set to 1 or greater, the tendency of the upper surface of the recess to be etched more easily than the lower surface of the recess cannot be offset, and the surface of the recess may not be etched conformally. As in the present embodiment, by setting ERRB / ERRA to less than 1, the tendency of the upper surface of the recess to be etched more easily than the lower surface of the recess can be offset, and the surface of the recess can be etched conformally. This effect can be enhanced by setting ERRB / ERRA to 0.9 or less, and further enhanced by setting ERRB / ERRA to 0.8 or less.

[0144] (h) By performing step C after etching the concave portion, the oxygen concentration on the surface of the concave portion after etching can be made uniform, and the oxygen concentration on the surface of the upper portion of the concave portion can be made equal to the oxygen concentration on the surface of the portion other than the upper portion of the concave portion. As a result, the composition (concentration of constituent elements, molecular structure, and film quality) of the surface of the concave portion after etching can be made uniform.

[0145] (i) The above-mentioned effects can also be similarly obtained when a predetermined substance is arbitrarily used from the above-mentioned various modifiers, various etchants, various oxidizing agents, various catalysts, and various inert gases.

[0146] <Second Aspect of the Invention>

[0147] This method differs from the first method described above in the following respects: In step A, a modifier containing an oxidizing agent is used to modify the surface of the upper portion of the recess so that the oxygen concentration increases compared to the oxygen concentration of the surfaces of other portions of the recess, thereby varying the oxygen concentrations of the respective surfaces. Furthermore, this method differs from the first method described above in the following respects: the etchant used in step B contains a first substance and a second substance, and in step B, the first and second substances are alternately supplied to the wafer 200. The following describes an example of the processing sequence of this method. The following description focuses on the differences from the first method.

[0148] Wafer filling, boat loading, pressure adjustment, and temperature adjustment are performed in the same manner as in the first embodiment.

[0149] (Step A)

[0150] Thereafter, a modifier including an oxidizing agent is excited and supplied to the wafer 200 having a recessed portion whose surface is made of an oxygen-containing substance.

[0151] Specifically, valve 243d is opened and a modifier (oxidant) flows into the gas supply pipe 232d. The modifier is flow-regulated by MFC241d, and after being excited into a plasma state by RPU300, it is supplied into the processing chamber 201 through nozzle 249a and exhausted from exhaust port 231a. At this time, the modifier excited into a plasma state is supplied to the wafer 200 from the side of the wafer 200 (modifier supply). In this way, the excited species generated by exciting the modifier, that is, the excited species (active species) generated by exciting the modifier into a plasma state, are supplied to the wafer 200. At this time, valves 243f~243h can also be opened to supply inactive gas into the processing chamber 201 through each of the nozzles 249a~249c.

[0152] Under the processing conditions described below, an oxidizing agent serving as a modifier is excited to a plasma state and supplied to the wafer 200. This allows the oxygen concentration (oxygen ratio, oxygen content) on the surface of the upper portion of the recess to vary, making the oxygen concentration on the surface of the upper portion of the recess different from the oxygen concentration on the surface of the other portions outside the upper portion of the recess. Specifically, a surface oxidation reaction based on the excited species can proceed in the upper portion of the recess, increasing the surface oxygen concentration. At this time, at least a portion of the excited species can be consumed and deactivated by reacting with the surface of the upper portion of the recess, reducing the supply of excited species per unit surface area in the other portions outside the upper portion of the recess compared to the upper portion of the recess. Consequently, surface oxidation reactions based on the excited species can be suppressed in the other portions outside the upper portion of the recess, reducing the increase in surface oxygen concentration. As a result, in step A, the oxygen concentration on the surface of the upper portion of the recess can be increased compared to the oxygen concentration on the surface of the other portions outside the upper portion of the recess.

[0153] The processing conditions when the modifier (oxidizing agent) is excited into a plasma state and supplied in step A can be the same as the processing conditions when the modifier (reducing agent) is excited into a plasma state and supplied in step A of the first embodiment.

[0154] After the oxygen concentration on the surface of the upper portion of the recess is changed (increased in this embodiment), valve 243d is closed to stop the supply of the modifier into the processing chamber 201. Then, the gaseous substances and the like remaining in the processing chamber 201 are removed (purged) from the processing chamber 201 by the same processing steps and processing conditions as those in step A of the first embodiment.

[0155] As the modifier (oxidant), the oxidant described in step C of the first embodiment, that is, the oxygen-containing gas, can be used. It should be noted that the process of exciting the oxygen-containing gas into a plasma state and supplying it to the wafer 200 is also referred to as oxygen-containing plasma treatment, and the active species (O2*, O*, etc.) generated at this time are also referred to as oxygen-containing active species (oxygen-containing free radicals).

[0156] (Step B)

[0157] After step A is completed, steps B1 and B2 are performed to alternately supply the first substance and the second substance as an etchant to the wafer 200 after the oxygen concentration on the surface of the upper portion of the recess has been changed (increased in this embodiment).

[0158] [Step B1]

[0159] In step B1, the first substance is supplied as an etchant from the etchant (first substance) supply system to the wafer 200. The processing steps in step B1 can be the same as those in step B of the first embodiment.

[0160] As the processing conditions when supplying the etching agent (first substance) in step B1, the following can be exemplified:

[0161] Treatment temperature: room temperature (25°C) to 400°C, preferably 50 to 250°C

[0162] Processing pressure: 1~13332Pa, preferably 1~1333Pa

[0163] Treatment time: 1 second to 120 minutes, preferably 1 minute to 60 minutes

[0164] First material supply flow rate: 0.001 to 2 slm

[0165] Inert gas supply flow rate (per gas supply pipe): 0 to 20 slm

[0166] After a predetermined time has passed, valve 243b is closed to stop the supply of the first substance into the processing chamber 201. Then, the gaseous substance remaining in the processing chamber 201 is removed (purged) from the processing chamber 201 through the same processing steps and processing conditions as those used in step A of the first embodiment. It should be noted that the processing temperature during the purge in this step is preferably the same as the processing temperature during the supply of the first substance.

[0167] As the first substance, various fluorine-based substances described in step B of the first embodiment can be used. As the first substance, one or more of these can be used.

[0168] [Step B2]

[0169] In step B2 , the second substance is supplied as an etchant to the wafer 200 from the etchant (second substance) supply system.

[0170] Specifically, valve 243c is opened to allow the second substance to flow into gas supply pipe 232c. The second substance is supplied into processing chamber 201 via nozzle 249c, with its flow rate regulated by MFC 241c, and exhausted from exhaust port 231a. At this point, the second substance is supplied to wafer 200 from the side (second substance supply). Alternatively, valves 243f to 243h may be opened to allow inert gas to be supplied into processing chamber 201 via nozzles 249a to 249c, respectively.

[0171] As the processing conditions when supplying the etching agent (second substance) in step B2, the following can be exemplified:

[0172] Treatment temperature: room temperature (25°C) to 400°C, preferably 50 to 250°C

[0173] Processing pressure: 1~13332Pa, preferably 1~1333Pa

[0174] Treatment time: 1 second to 120 minutes, preferably 1 minute to 60 minutes

[0175] Second material supply flow rate: 0.001 to 2 slm

[0176] Inert gas supply flow rate (per gas supply pipe): 0 to 20 slm

[0177] After a predetermined time has passed, valve 243c is closed to stop the supply of the second substance into the processing chamber 201. Then, the gaseous substance remaining in the processing chamber 201 is removed (purged) from the processing chamber 201 by the same processing steps and processing conditions as those used in step A of the first embodiment. It should be noted that the processing temperature during the purge in this step is preferably the same as the processing temperature during the supply of the second substance.

[0178] As the second substance, various fluorine-based substances described in step B of the first embodiment can be used. Furthermore, as the second substance, ammonia (NH3) gas, H2 gas, O2 gas, NO gas, O3 gas, H2O gas, isopropyl alcohol ((CH3)2CHOH) gas, methanol (CH3OH) gas, boron trichloride (BCl3) gas, chlorine (Cl2) gas, hydrogen chloride (HCl) gas, etc. can be used. As the second substance, one or more of these can be used.

[0179] For example, when F2 gas is used as the first substance, the second substance may include HF gas, ClF3 gas, ClF gas, NF3 gas, FNO gas, NH3 gas, H2 gas, O2 gas, NO gas, O3 gas, H2O gas, (CH3)2CHOH gas, CH3OH gas, BCl3 gas, Cl2 gas, or HCl gas. Furthermore, when HF gas is used as the first substance, the second substance may include F2 gas, ClF3 gas, ClF gas, NF3 gas, FNO gas, NH3 gas, H2 gas, O2 gas, NO gas, O3 gas, H2O gas, (CH3)2CHOH gas, CH3OH gas, BCl3 gas, Cl2 gas, or HCl gas. Thus, it is preferred that at least one of the first and second substances contain F, but both the first and second substances may contain F.

[0180] [Alternate implementation]

[0181] By alternately performing step B1 and step B2 a predetermined number of times (m times, where m is an integer of 1 or 2 or greater), at least a portion of the surface of the recessed portion can be etched.

[0182] It should be noted that in this method, when step B is implemented instead of step A, there is also the following tendency: in other parts other than the upper part of the recess, the supply amount of the etchant per unit surface area is likely to be reduced compared to the upper part of the recess, making it difficult to etch the surface of the recess conformally.

[0183] In contrast, in this method, step A is performed before step B. As a result, the oxygen concentration in the surface of the upper portion of the recessed portion to be etched can be made different from the oxygen concentration in the surface of the other portions other than the upper portion of the recessed portion. Specifically, it is possible to set the state in which the oxygen concentration in the surface of the upper portion of the recessed portion to be etched is increased compared to the oxygen concentration in the surface of the other portions other than the upper portion of the recessed portion. Then, in step B, the substance used as the etchant, the processing steps, and the processing conditions are appropriately selected to create a situation in which it is difficult to etch an object with a high oxygen concentration, but it is easy to etch an object with a low oxygen concentration (to exert the prescribed etching selectivity). As a result, when etching the surface of the recessed portion, it is possible to suppress the reduction in the etching rate on the surface of the other portions other than the upper portion of the recessed portion, and selectively reduce the etching rate on the surface of the upper portion of the recessed portion. That is, it is possible to adjust the etching rate on the surface of the upper portion of the recessed portion in a direction close to the etching rate on the surface of the other portions other than the upper portion of the recessed portion.

[0184] As a result, this method can also reduce the etching rate of the upper surface of the recessed portion relative to the lower surface of the recessed portion, and can offset the aforementioned tendency of the upper surface of the recessed portion to be easily etched relative to the lower surface of the recessed portion. This makes it possible to make the etching amount on the surface of the recessed portion uniform, and the surface of the recessed portion can be etched conformally. This method can also set the ratio of ERRB to ERRA (ERRB / ERRA) to 0.01 or more and less than 1, preferably 0.02 or more and 0.9 or less, and more preferably 0.05 or more and 0.8 or less.

[0185] In this embodiment, when step B is performed, the entire modified portion may be removed, or a portion of the modified portion may remain.

[0186] (Implemented at specified times)

[0187] By performing the cycle including the above-mentioned steps A and B a predetermined number of times (n times, where n is an integer of 1 or 2 or greater), the surface of the recessed portion can be conformally etched by a predetermined amount, similarly to the first embodiment.

[0188] Thereafter, similarly to the first embodiment, step C is performed as needed, and further post-purge, atmospheric pressure restoration, boat unloading, and wafer removal are performed.

[0189] This embodiment can also achieve the same effects as the first embodiment. That is, in this embodiment, by performing steps A and B a predetermined number of times, when etching the surface of the recessed portion of the substrate, the tendency of the upper surface of the recessed portion to be etched more easily than the lower surface of the recessed portion can be offset.

[0190] Furthermore, in this embodiment, by including an oxidizing agent in the modifier, the above-mentioned action can be effectively produced, and the operation of selectively changing the oxygen concentration in the surface of the upper portion of the recess can be effectively performed.

[0191] In this embodiment, the above-mentioned effect can be effectively produced by including an oxygen-containing gas in the modifier, that is, by performing an oxygen-containing plasma treatment in step A.

[0192] Furthermore, in this embodiment, the above-described action can be effectively produced by making the etchant contain the first substance and the second substance, and at least one of the first substance and the second substance contain fluorine.

[0193] Furthermore, in step B of this embodiment, the above-mentioned effect can be more effectively produced by alternately supplying the first substance and the second substance to the substrate.

[0194] <Other aspects of the present invention>

[0195] While the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the present invention.

[0196] For example, in the first embodiment, in step A, an inert gas serving as a modifier may be excited into a plasma state and supplied.

[0197] As the processing conditions when the modifier (inert gas) is excited into a plasma state and supplied in step A, the following can be exemplified:

[0198] Modifier (inert gas) supply flow rate: 0.01 to 10 slm, preferably 0.1 to 5 slm.

[0199] Other processing conditions can be the same as those in step A of the first embodiment.

[0200] As the modifier (inert gas), various inert gases described in the above-mentioned embodiments can be used. It should be noted that the process of exciting an inert gas to a plasma state and supplying it to the wafer 200 is also referred to as inert gas plasma treatment. Furthermore, the process of exciting a noble gas, among the inert gases, to a plasma state and supplying it is also referred to as noble gas plasma treatment. Furthermore, the active species (N2*, N*, Ar*, He*, Ne*, Xe*, etc.) generated during this process are also referred to as inert gas active species or noble gas active species (inert gas radicals or noble gas radicals).

[0201] In this embodiment as well, the tendency that the upper surface of the recessed portion is easily etched relative to the lower surface of the recessed portion can be offset, and the same effects as those of the above embodiment can be obtained.

[0202] Furthermore, for example, in the second embodiment, in step A, the modifier containing the oxidant can be supplied by thermal excitation in a non-plasma atmosphere. In this case, a catalyst can be supplied together with the oxidant. Furthermore, the supply of the catalyst can be omitted.

[0203] As treatment conditions when supplying the modifying agent (oxidizing agent) by thermal excitation in step A, the following can be exemplified:

[0204] Processing temperature: room temperature (25°C) to 600°C, preferably 50 to 400°C

[0205] Processing pressure: 1-10000Pa, preferably 50-3000Pa

[0206] Processing time: 1 to 600 seconds, preferably 5 to 300 seconds

[0207] Modifier supply flow rate: 0.01~10slm, preferably 0.1~5slm

[0208] Catalyst supply flow rate: 0-10slm, preferably 0-5slm

[0209] Inert gas supply flow rate (per gas supply pipe): 0 to 20 slm

[0210] As the modifier (oxidant) and catalyst, the oxidant (oxygen-containing gas) and catalyst described in the above embodiment can be used, respectively. Note that the process of supplying the oxygen-containing gas to the wafer 200 by thermal excitation is also referred to as thermal oxidation.

[0211] In this embodiment as well, the tendency that the upper surface of the recessed portion is easily etched relative to the lower surface of the recessed portion can be offset, and the same effects as those of the above embodiment can be obtained.

[0212] Alternatively, for example, after the etching process is performed, step C may be performed by introducing atmospheric air into the processing chamber. Alternatively, for example, after the etching process is performed, post-purge, atmospheric pressure restoration, and wafer boat unloading may be performed, thereby exposing the etched wafer 200 to the atmosphere and performing step C. In such a case, O2, H2O, or the like contained in the atmosphere is used as an oxidizing agent to oxidize the surface of the recessed portion after at least a portion of the recessed portion has been etched. In such a case, the same effects as those of the above-described embodiment can be achieved.

[0213] Furthermore, for example, the surface of the recessed portion of wafer 200 may be formed of a substance containing a metal element such as tungsten (W), molybdenum (Mo), ruthenium (Ru), titanium (Ti), zirconium (Zr), hafnium (Hf), or aluminum (Al), and oxygen, that is, a metal oxide. Furthermore, the surface of the recessed portion may be formed of a W film, Mo film, Ru film, TiN film, ZrN film, HfN film, or AlN film having a natural oxide film formed on the surface, that is, a conductive or non-conductive metal-containing film having a natural oxide film formed on the surface. This embodiment also achieves the same effects as the above embodiment.

[0214] The recipe used in each treatment is preferably prepared individually according to the treatment content, recorded and pre-stored in the storage device 121c via an electrical communication line or external storage device 123. Furthermore, when each treatment is started, the CPU 121a preferably selects an appropriate recipe from the multiple recipes recorded and stored in the storage device 121c, corresponding to the treatment content. This allows the treatment apparatus to perform etching treatments for films of various film types, composition ratios, film qualities, and film thicknesses with high reproducibility. Furthermore, each treatment can be started quickly while reducing the burden on the operator and preventing operational errors.

[0215] The above-described process is not limited to newly created processes; for example, it can also be prepared by modifying an existing process already installed in a processing device. When modifying a process, the modified process can be installed in the processing device via a communication line or a recording medium containing the process. Furthermore, it is also possible to modify an existing process installed in the processing device directly by operating the input / output device 122 of the existing processing device.

[0216] The above-described embodiment describes an example of etching using a batch-type processing apparatus that processes multiple substrates at a time. The present invention is not limited to the above-described embodiment and can also be appropriately applied to etching using a single-wafer processing apparatus that processes one or several substrates at a time. Furthermore, the above-described embodiment describes an example of etching using a processing apparatus with a hot-wall processing furnace. The present invention is not limited to the above-described embodiment and can also be appropriately applied to etching using a processing apparatus with a cold-wall processing furnace.

[0217] Furthermore, the above-described method describes an example in which the above-described processing sequence is performed in the same processing chamber of the same processing apparatus (in-situ). The present invention is not limited to the above-described method. For example, any step and any other step of the above-described 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.

[0218] When the above-mentioned processing apparatus is used, each process can be performed in the same processing steps and processing conditions as those of the above-mentioned embodiment and modification examples, and the same effects as those of the above-mentioned embodiment and modification examples can be obtained.

[0219] The above-mentioned embodiments and modifications can be used in combination as appropriate. The processing steps and processing conditions in this case can be, for example, the same as those in the above-mentioned embodiments and modifications.

Claims

1. A processing method comprising the step of etching at least a portion of the surface of a recessed portion by performing a cycle including the following (a) and (b) a predetermined number of times: (a) a step of exciting and supplying a modifier to the substrate having the recessed portion whose surface is composed of a substance containing oxygen, thereby changing the oxygen concentration in the surface of the upper portion of the recessed portion; and (b) A step of supplying an etchant to the substrate after changing the oxygen concentration on the surface of the upper portion of the recess.

2. The processing method according to claim 1, wherein: In (a), excited species generated by exciting the modifying agent are supplied to the substrate.

3. The processing method according to claim 1, wherein: In (a), the modifying agent is excited into a plasma state and supplied to the substrate.

4. The processing method according to claim 1, wherein: In (a), an excited species generated by exciting the modifier into a plasma state is supplied to the substrate.

5. The processing method according to any one of claims 1 to 4, wherein: The modifying agent includes at least any one of a reducing agent and an oxidizing agent.

6. The processing method according to any one of claims 1 to 4, wherein: The modifier includes at least any one of a hydrogen-containing gas, a deuterium-containing gas, and an oxygen-containing gas.

7. The processing method according to any one of claims 1 to 4, wherein: In (a), at least one of hydrogen-containing plasma treatment, deuterium-containing plasma treatment, inert gas plasma treatment, oxygen-containing plasma treatment, and thermal oxidation treatment is performed on the substrate.

8. The processing method according to any one of claims 1 to 4, wherein: In (a), the oxygen concentration in the surface of the upper portion of the recessed portion is made different from the oxygen concentration in the surface of the other portion of the recessed portion other than the upper portion.

9. The processing method according to any one of claims 1 to 4, wherein: The surface of the recessed portion is made of oxide.

10. The processing method according to any one of claims 1 to 4, wherein: The surface of the recessed portion is made of a substance including silicon and oxygen.

11. The processing method according to any one of claims 1 to 4, wherein: The surface of the recessed portion is made of silicon oxide.

12. The processing method according to any one of claims 1 to 4, wherein: The etchant contains fluorine.

13. The processing method according to any one of claims 1 to 4, wherein: The etchant includes fluorine and hydrogen.

14. The processing method according to any one of claims 1 to 4, wherein: The etching agent includes a first substance and a second substance, and at least one of the first substance and the second substance includes fluorine.

15. The processing method according to claim 14, wherein: In (b), the first substance and the second substance are supplied alternately.

16. The processing method according to any one of claims 1 to 4, wherein: When the ratio of the etching rate on the upper surface of the recess caused by the etchant to the etching rate on the lower surface of the recess when (a) is not performed is set to ERRA, and the ratio of the etching rate on the upper surface of the recess caused by the etchant to the etching rate on the lower surface of the recess when (a) is performed is set to ERRB, the ratio of ERRB to ERRA, i.e. ERRB / ERRA, is set to be greater than 0.01 and less than 1.

17. The processing method according to any one of claims 1 to 4, further comprising: (c) A step of oxidizing a surface of the recessed portion after etching at least a portion of the recessed portion.

18. The processing method according to any one of claims 1 to 4, further comprising: (c) A step of making the oxygen concentration on the surface of the recessed portion uniform after etching at least a portion of the recessed portion.

19. A method for manufacturing a semiconductor device, comprising the step of etching at least a portion of a surface of a recessed portion by performing a cycle including the following (a) and (b) a predetermined number of times: (a) a step of exciting and supplying a modifier to the substrate having the concave portion whose surface is composed of a substance containing oxygen, thereby changing the oxygen concentration on the surface of the upper portion of the concave portion; and (b) A step of supplying an etchant to the substrate after changing the oxygen concentration on the surface of the upper portion of the recess.

20. A processing device comprising: a modifying agent supplying system for supplying a modifying agent to the substrate; an etchant supply system that supplies the etchant to the substrate; an exciting portion that excites the modifying agent; and A control unit configured to control the modifier supply system, the etchant supply system, and the excitation unit to perform a process of etching at least a portion of the surface of the recessed portion by performing a cycle including the following (a) and (b) a predetermined number of times: (a) a process for supplying an etchant to a substrate having a recessed portion whose surface is composed of a substance containing oxygen, thereby changing the oxygen concentration in the upper surface of the recessed portion by exciting the modifier; and (b) a process for supplying an etchant to the substrate after changing the oxygen concentration in the upper surface of the recessed portion.

21. A computer-readable recording medium recording a program for causing a processing device to execute, by using a computer, a step of etching at least a portion of a surface of a recessed portion by performing a cycle including the following (a) and (b) a predetermined number of times: (a) with respect to the substrate having the recessed portion whose surface is composed of a substance containing oxygen, a step of exciting and supplying a modifier to change the oxygen concentration in the surface of the upper portion of the recessed portion; and (b) A step of supplying an etchant to the substrate after changing the oxygen concentration on the surface of the upper portion of the recess.

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