Patent Application
20240105448
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2022-152708, filed on Sep. 26, 2022, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a method of processing a substrate, a method of manufacturing a semiconductor device, a substrate processing system, and a recording medium.
In the related art, as a process of manufacturing a semiconductor device, a process of selectively growing and forming a film on a specific surface among a plurality of types of surfaces of a substrate in which materials exposed on the surfaces are different (hereinafter, this process is also referred to as selective growth or selective film formation) may be carried out.
Some embodiments of the present disclosure provide a technique capable of selectively forming a film on a desired surface with high precision.
According to some embodiments of the present disclosure, there is provided a technique that includes: (a) performing: (a1) exciting a first oxidizing agent and a first reducing agent into a plasma state and supplying the first oxidizing agent and the first reducing agent thus excited to a substrate, which includes a first surface and a second surface; and (a2) exciting a second reducing agent into a plasma state and supplying the second reducing agent thus excited to the substrate; and (b) heat-treating the substrate subjected to (a).
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure.
Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, systems, and components are not described in detail so as not to unnecessarily obscure aspects of the various embodiments.
Embodiments of the present disclosure will now be described mainly with reference to
As shown in
A reaction tube 203 is disposed inside the heater 207 to be concentric with the heater 207. The reaction tube 203 is made of, for example, a heat resistant material such as quartz (SiO2) or silicon carbide (SiC), and is formed in a cylindrical shape with its upper end closed and its lower end opened. A manifold 209 is disposed to be concentric with the reaction tube 203 under the reaction tube 203. The manifold 209 is made of, for example, a metal material such as stainless steel (SUS), and is formed in a cylindrical shape with both of its upper and lower ends opened. An upper end side of the manifold 209 engages with a lower end side of the reaction tube 203 so as to support the reaction tube 203. An O-ring 220a serving as a seal is provided between the manifold 209 and the reaction tube 203. Similar to the heater 207, the reaction tube 203 is vertically installed. A process container (reaction container) mainly includes the reaction tube 203 and the manifold 209. A process chamber 201 is formed in a hollow cylindrical area of the process container. The process chamber 201 is configured to be capable of accommodating wafers 200 as substrates. Processing on the wafers 200 is performed in the process chamber 201.
Nozzles 249a to 249c as first to third suppliers are installed in the process chamber 201 so as to penetrate through a sidewall of the manifold 209. The nozzles 249a to 249c are also referred to as first to third nozzles, respectively. The nozzles 249a to 249c are made of, for example, 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 each of the nozzles 249a and 249c is installed adjacent to the nozzle 249b.
Mass flow controllers (MFCs) 241a to 241c, which are flow rate controllers (flow rate control parts), and valves 243a to 243c, which are opening/closing valves, are installed at the gas supply pipes 232a to 232c, respectively, sequentially from the upstream side of a gas flow. Each of gas supply pipes 232d and 232f is connected to the gas supply pipe 232a at the downstream side of the valves 243a. Each of gas supply pipes 232e and 232g is connected to the gas supply pipe 232b at the downstream side of the valves 243b. A gas supply pipe 232h is connected to the gas supply pipe 232c at the downstream side of the valves 243c. MFCs 241d to 241h and valves 243d to 243h are installed at the gas supply pipes 232d to 232h, respectively, sequentially from the upstream side of a gas flow. The gas supply pipes 232a to 232h are made of, for example, a metal material such as SUS.
As shown in
A modifying agent (modifying gas) is supplied from the gas supply pipe 232a into the process chamber 201 via the MFC 241a, the valve 243a, and the nozzle 249a.
A precursor (precursor gas), which is a film-forming agent (film-forming gas), and a reducing agent (reducing gas) are supplied from the gas supply pipe 232b into the process chamber 201 via the MFC 241b, the valve 243b, and the nozzle 249b.
A reactant (reaction gas), which is a film-forming agents (film-forming gas), are supplied from the gas supply pipe 232c into the process chamber 201 via the MFC 241c, the valve 243c, and the nozzle 249c.
A catalyst (catalyst gas), which is a film-forming agents (film-forming gas), are supplied from the gas supply pipe 232d into the process chamber 201 via the MFC 241d, the valve 243d, the gas supply pipe 232a, and the nozzle 249a.
An etching agent (etching gas) and an oxidizing agent (oxidizing gas) are supplied from the gas supply pipe 232e into the process chamber 201 via the MFC 241e, the valve 243e, the gas supply pipe 232b, and the nozzle 249b.
An inert gas is supplied from the gas supply pipes 232f to 232h into the process chamber 201 via the MFCs 241f to 241h, the valves 243f to 243h, the gas supply pipes 232a to 232c, and the nozzles 249a to 249c, respectively. The inert gas acts as a purge gas, a carrier gas, a dilution gas, or the like.
A remote plasma unit (RPU) 300, as a plasma exciter (plasma generator) configured to excite a gas into a plasma state, is installed at the downstream side of a connector of the gas supply pipe 232b with the gas supply pipe 232g. Exciting a gas into a plasma state is also simply referred to as plasma excitation. By applying radio-frequency (RF) power to the RPU 300, it is possible to turn a gas inside the RPU 300 into plasma to excite the gas, that is, to excite the gas into a plasma state. As a plasma generation method, a capacitively-coupled plasma (abbreviation: CCP) method may be used, or an inductively-coupled plasma (abbreviation: ICP) method may be used. The RPU 300 is configured to be able to excite the reducing agent, the oxidizing agent, and the inert gas supplied from the gas supply pipes 232b, 232e, and 232g into a plasma state and supply them into the process chamber 201.
A modifying agent supply system mainly includes the gas supply pipe 232a, the MFC 241a, and the valve 243a. A precursor supply system and a reducing agent supply system mainly include the gas supply pipe 232b, the MFC 241b, and the valve 243b. A reactant supply system mainly includes the gas supply pipe 232c, the MFC 241c, and the valve 243c. A catalyst supply system mainly includes the gas supply pipe 232d, the MFC 241d, and the valve 243d. An etching agent supply system and an oxidizing agent supply system mainly include the gas supply pipe 232e, the MFC 241e, and the valve 243e. An inert gas supply system mainly includes the gas supply pipes 232f to 232h, the MFCs 241f to 241h, and the valves 243f to 243h. Each or both of the precursor supply system and the reactant supply system are also referred to as a film-forming agent supply system. Each or the entirety of the precursor supply system, the reactant supply system, and the catalyst supply system are also referred to as a film-forming agent supply system.
One or the entirety of the above-described various supply systems may be constituted as an integrated supply system 248 in which the valves 243a to 243h, the MFCs 241a to 241h, and so on are integrated. The integrated supply system 248 is connected to each of the gas supply pipes 232a to 232h. In addition, the integrated supply system 248 is configured such that operations of supplying various materials (various gases) into the gas supply pipes 232a to 232h (that is, the opening/closing operation of the valves 243a to 243h, the flow rate regulating operation by the MFCs 241a to 241h, and the like) are controlled by a controller 121 described below. The integrated supply system 248 is constituted as an integral or detachable integrated unit, and may be attached to or detached from the gas supply pipes 232a to 232h and the like on an integrated unit basis, such that maintenance, replacement, extension, and the like of the integrated supply system 248 may be performed on an integrated unit basis.
The exhaust port 231a configured to exhaust an internal atmosphere of the process chamber 201 is provided below the sidewall of the reaction tube 203. As shown in
A seal cap 219, which serves as a furnace opening lid configured to be capable of hermetically sealing a lower end opening of the manifold 209, is installed under the manifold 209. The seal cap 219 is made of, for example, a metal material such as SUS, and is formed in a disc shape. An O-ring 220b, which is a seal making contact with the lower end of the manifold 209, is installed on an upper surface of the seal cap 219. A rotator 267 configured to rotate a boat 217 described below, is installed under the seal cap 219. A rotary shaft 255 of the rotator 267 is connected to the boat 217 through the seal cap 219. The rotator 267 is configured to rotate the wafers 200 by rotating the boat 217. The seal cap 219 is configured to be vertically moved up or down by a boat elevator 115 which is an elevator installed outside the reaction tube 203. The boat elevator 115 is constituted as a transfer apparatus (transfer equipment) configured to load or unload (transfer) the wafers 200 into or out of the process chamber 201 by moving the seal cap 219 up or down.
A shutter 219s, which serves as a furnace opening lid configured to be capable of hermetically sealing a lower end opening of the manifold 209 in a state where the seal cap 219 is lowered and the boat 217 is unloaded from the process chamber 201, is installed under the manifold 209. The shutter 219s is made of, for example, a metal material such as SUS, and is formed in a disc shape. An O-ring 220c, which is a seal making contact with the lower end of the manifold 209, is installed on an upper surface of the shutter 219s. The opening/closing operation (such as elevation operation, rotation operation, or the like) of the shutter 219s is controlled by a shutter opening/closing equipment 115s.
The boat 217 serving as a substrate support is configured to support a plurality of wafers 200, for example, 25 to 200 wafers, in such a state that the wafers 200 are arranged in a horizontal posture and in multiple stages along a vertical direction with the centers of the wafers 200 aligned with one another. That is, the boat 217 is configured to arrange the wafers 200 to be spaced apart from each other. The boat 217 is made of, for example, a heat resistant material such as quartz or SiC. Heat insulating plates 218 made of, for example, a heat resistant material such as quartz or SiC are installed below the boat 217 in multiple stages.
A temperature sensor 263 serving as a temperature detector is installed in the reaction tube 203. Based on temperature information detected by the temperature sensor 263, a state of supplying electric power to the heater 207 is regulated such that a temperature distribution inside the process chamber 201 becomes a desired temperature distribution. The temperature sensor 263 is installed along the inner wall of the reaction tube 203.
As shown in
The memory 121c includes, for example, a flash memory, a hard disk drive (HDD), a solid state drive (SSD), or the like. A control program that controls operations of a substrate processing apparatus, a process recipe in which sequences and conditions of substrate processing described below are written, and the like are readably stored in the memory 121c. The process recipe functions as a program configured to cause, by the controller 121, the substrate processing apparatus (substrate processing system) to execute each sequence in the substrate processing described below, to obtain an expected result. Hereinafter, the process recipe and the control program may be generally and simply referred to as a “program.” Furthermore, the process recipe may be simply referred to as a “recipe.” When the term “program” is used herein, it may indicate a case of including the recipe, a case of including the control program, or a case of including both the recipe and the control program. The RAM 121b is constituted as a memory area (work area) in which programs or data read by the CPU 121a are temporarily stored.
The I/O port 121d is connected to the MFCs 241a to 241h, the valves 243a to 243h, the pressure sensor 245, the APC valve 244, the vacuum pump 246, the temperature sensor 263, the heater 207, the rotator 267, the boat elevator 115, the shutter opening/closing equipment 115s, the RPU 300, and so on.
The CPU 121a is configured to be capable of reading and executing the control program from the memory 121c. The CPU 121a is also configured to be capable of reading the recipe from the memory 121c according to an input of an operation command from the input/output device 122. The CPU 121a is configured to be capable of controlling the flow rate regulating operation of various kinds of materials (gases) by the MFCs 241a to 241h, the opening/closing operation of the valves 243a to 243h, the opening/closing operation of the APC valve 244, the pressure regulating operation performed by the APC valve 244 based on the pressure sensor 245, the actuating and stopping operation of the vacuum pump 246, the temperature regulating operation performed by the heater 207 based on the temperature sensor 263, the operation of rotating the boat 217 with the rotator 267 and adjusting a rotation speed of the boat 217, the operation of moving the boat 217 up or down by the boat elevator 115, the opening/closing operation of the shutter 219s by the shutter opening/closing equipment 115s, the operation of exciting the gas into the plasma by the RPU 300, and so on, according to contents of the read recipe.
The controller 121 may be constituted by installing, on the computer, the aforementioned program recorded and stored in the external memory 123. Examples of the external memory 123 may include a magnetic disk such as a HDD, an optical disc such as a CD, a magneto-optical disc such as a MO, a semiconductor memory such as a USB memory or a SSD, and the like. The memory 121c or the external memory 123 is constituted as a computer-readable recording medium. Hereinafter, the memory 121c and the external memory 123 may be generally and simply referred to as a “recording medium.” When the term “recording medium” is used herein, it may indicate a case of including the memory 121c, a case of including the external memory 123, or a case of including both the memory 121c and the external memory 123. Furthermore, the program may be provided to the computer by using communication means or unit such as the Internet or a dedicated line, instead of using the external memory 123.
As a process of manufacturing a semiconductor device in which the above-described substrate processing apparatus (substrate processing system) is used, an example of a method of processing a substrate, that is, a processing sequence of forming a film on a first surface of a wafer 200 as a substrate of the first surface and a second surface of the wafer 200, will be described mainly with reference to
Here, as shown in
More specifically, a laminated structure formed by alternately laminating the first material (SiGe) and the second material (Si) is formed on the surface of the wafer 200, the third material (SiN) is formed over the laminated structure, and the fourth material (SiO) is formed on the third material. Further, the fourth material (SiO) is formed between the third material (SiN) and the laminated structure of the first material (SiGe) and the second material (Si). That is, the laminated structure formed by alternately laminating the SiGe film and the Si film is formed on the surface of the wafer 200, the SiO film is formed on the laminated structure, the SiN film is formed on the SiO film, and the SiO film is formed on the SiN film. By partially removing a portion, which is constituted by the SiGe film, of the side wall of the laminated structure of the SiGe film and the Si film, a recess whose top surface and side surface are constituted by the second material (Si), whose bottom surface is constituted by the first material (SiGe), and whose depth direction is a direction (horizontal direction) parallel to the surface of the wafer 200 is formed on the side wall of the laminated structure. In the present disclosure, as shown in
Further, symbols A, A1, A2, B, C, D, E, and F in
A processing sequence shown in
The processing temperature in step B may be equal to or higher than the processing temperature in step A. Further, a processing temperature in step B may be equal to or higher than each of processing temperatures in steps A and C. Further, the processing temperature in step B may be equal to or higher than each of the processing temperatures in steps A, C, and D. The processing sequence shown in
In step A, a high-density hydroxyl group termination (hereinafter, also referred to as an OH termination or an OH group) is formed on the first surface and the second surface of the wafer 200, and in step B, the high-density OH termination formed on the first surface is removed while leaving the high-density OH termination formed on the second surface. More specifically, in step A, the high-density OH termination is formed on the first surface, the second surface, and at least one selected from the group of the third surface and the fourth surface of the wafer 200, and in step B, the high-density OH termination formed on the first surface is removed while leaving the high-density OH termination formed on the second surface and the at least one selected from the group of the third surface and the fourth surface. Further, in the embodiments of the present disclosure, in step A, the high-density OH termination is formed on the first surface, the second surface, and the third surface of the wafer 200. Since the fourth surface is constituted by the SiO film, a sufficient amount of OH termination is formed on the fourth surface before step A is performed. However, in a case such as when the OH termination on the fourth surface is insufficient, the OH termination on the fourth surface may be reinforced in step A. Accordingly, in the embodiments of the present disclosure, by performing step A, the high-density OH termination may be formed on each of the first surface, the second surface, the third surface, and the fourth surface (each surface may contains the high-density OH termination), and by performing step B, the high-density OH termination formed on the first surface may be removed while maintaining a state in which the high-density OH termination is formed on each of the second surface, the third surface, and the fourth surface (each surface contains the high-density OH termination).
That is, in step A, the first surface and the second surface are oxidized (plasma-oxidized) to be modified, and in step B, an oxide (oxide film) formed on the first surface is sublimated to be removed while leaving an oxide (oxide film) formed on the second surface. More specifically, in step A, the first surface, the second surface, and at least one selected from the group of the third surface and the fourth surface are oxidized to be modified, and in step B, an oxide formed on the first surface is sublimated to be removed while leaving an oxide formed on the second surface and at least one selected from the group of the third surface and the fourth surface. In the embodiments of the present disclosure, in step A, the first surface, the second surface, and the third surface of the wafer 200 are oxidized to be modified. Since the fourth surface is constituted by the SiO film, the fourth surface is not be oxidized. However, in a case where the fourth surface contains an oxidizable element, the fourth surface may also be oxidized to be modified. Accordingly, in the embodiments of the present disclosure, by performing step A, each of the first surface, the second surface, the third surface, and the fourth surface of the wafer 200 may be oxidized (each surface may contain an oxide), and by performing step B, the oxide formed on the first surface may be sublimated to be removed while maintaining a state in which each of the second surface, the third surface, and the fourth surface is oxidized (each surface contains an oxide). Further, in step A, the oxide formed on the first surface, the second surface, and the third surface of the wafer 200 is constituted by a very thin, uniform, and layer-like or film-like material. Such a very thin, uniform, and layer-like or film-like oxide is also referred to simply as an oxide layer or an oxide film.
By oxidizing and modifying each surface as described above, a high-density OH termination may be formed on each surface. Further, by leaving (maintaining) an oxide on a predetermined surface, the high-density OH termination may be leaved (maintained) on the predetermined surface. Further, by sublimating and removing an oxide on a specific surface, the OH termination on the specific surface may be removed. As a result, the second surface, the third surface, and the fourth surface before performing step C contain the high-density OH termination. On the other hand, the first surface before performing step C does not contain an OH termination, or contains an OH termination of an amount that is much smaller than an amount of OH termination on the second surface, the third surface, and the fourth surface.
The processing sequence shown in
The processing sequence shown in
More specifically, as shown in
In the present disclosure, for the sake of convenience, the above-described processing sequence may also be denoted as follows. The same notation is also used in the description of modifications and other embodiments described below. Further, the notations “oxidizing agent*” and “reducing agent*” mean an oxidizing agent and a reducing agent excited into a plasma state, respectively.
Oxidizing agent*+Reducing agent*→Reducing agent*→Heat treatment→Modifying agent→(Precursor+Catalyst→Reactant+Catalyst)×n
At this time, as in the processing sequence shown below, depending on process conditions, the catalyst may not be supplied, or the catalyst may be supplied to the wafer 200 in at least one selected from the group of step D1 and step D2.
Oxidizing agent*+Reducing agent*→Reducing agent*→Heat treatment→Modifying agent→(Precursor→Reactant)×n
Oxidizing agent*+Reducing agent*→Reducing agent*→Heat treatment→Modifying agent→(Precursor+Catalyst→Reactant)×n
Oxidizing agent*+Reducing agent*→Reducing agent*→Heat treatment→Modifying agent→(Precursor→Reactant+Catalyst)×n
Oxidizing agent*+Reducing agent*→Reducing agent*→Heat treatment→Modifying agent→(Precursor+Catalyst→Reactant+Catalyst)×n
Further, the processing sequence shown in
Further, the processing sequence shown in
In the embodiments of the present disclosure, an example in which the first surface is the surface of the SiGe film, the second surface is the surface of the Si film, the third surface is the surface of the SiN film, the fourth surface is the surface of the SiO film, and in step D, a silicon oxycarbide film (SiOC film), which is a film containing silicon (Si), oxygen (O), and carbon (C), or a silicon oxide film (SiO film), which is a film containing silicon (Si) and oxygen (O), is grown as a film will be described.
When the term “wafer” is used in the present disclosure, it may refer to a wafer itself” or “a stacked body of a wafer and certain layers or films formed on a surface of the wafer.” When the phrase “a surface of a wafer” is used in the present disclosure, it may refer to “a surface of a wafer itself” or “a surface of a certain layer formed on a wafer.” When the expression “a certain layer is formed on a wafer” is used in the present disclosure, it may mean that “a certain layer is formed directly on a surface of a wafer itself” or that “a certain layer is formed on a layer formed on a wafer.” When the term “substrate” is used in the present disclosure, it may be synonymous with the term “wafer.”
The term “agent” used in the present disclosure includes at least one selected from the group of a gaseous substance and a liquefied substance. The liquefied substance includes a misty substance. That is, each of the etching agent, the oxidizing agent, the reducing agent, the modifying agent, and the film-forming agent (the precursor, the reactant, and the catalyst) may include a gaseous substance, a liquefied substance such as a misty substance, or both of them.
The term “layer” used in the present disclosure includes at least one selected from the group of a continuous layer and a discontinuous layer. For example, the inhibitor layer may include a continuous layer, a discontinuous layer, or both of them as long as it may cause a film-forming inhibitory action (adsorption inhibitory action or reaction inhibitory action).
After the boat 217 is charged with a plurality of wafers 200 (wafer charging), the shutter 219s is moved by the shutter opening/closing equipment 115s and the lower end opening of the manifold 209 is opened (shutter open). Thereafter, as shown in
After the boat loading is completed, the interior of the process chamber 201, that is, a space where the wafers 200 are placed, is vacuum-exhausted (decompression-exhausted) by the vacuum pump 246 to reach a desired pressure (state of vacuum). At this time, the internal pressure of the process chamber 201 is measured by the pressure sensor 245, and the APC valve 244 is feedback-controlled based on the measured pressure information. Further, the wafers 200 in the process chamber 201 are heated by the heater 207 so as to reach a desired temperature. At this time, a state of supplying electric power to the heater 207 is feedback-controlled based on the temperature information detected by the temperature sensor 263 such that a temperature distribution inside the process chamber 201 becomes a desired temperature distribution. Further, the rotation of the wafers 200 by the rotator 267 is started. The exhaust of the interior of the process chamber 201 and the heating and rotation of the wafers 200 are continuously performed at least until the processing on the wafers 200 is completed.
Thereafter, an etching agent is supplied to the wafer 200.
Specifically, the valve 243e is opened to allow the etching agent (etching gas) to flow through the gas supply pipe 232e. A flow rate of the etching agent is regulated by the MFC 241e, and the etching agent is supplied into the process chamber 201 via the gas supply pipe 232b and the nozzle 249b and is exhausted via the exhaust port 231a. In this operation, the etching agent is supplied to the wafer 200 from the side of the wafer 200 (etching agent supply). At this time, the valves 243f to 243h may be opened to allow an inert gas to be supplied into the process chamber 201 via the nozzles 249a to 249c, respectively.
By supplying the etching agent to the wafer 200 under a process condition described below, a native oxide film formed on the surface of the wafer 200 may be removed. That is, the native oxide film on the first surface and the second surface of the wafer 200 may be removed. Specifically, the native oxide film on the surface of the recess whose top surface and side surface formed on the surface of the wafer 200 are constituted by the Si film, whose bottom surface is constituted by the SiGe film, and whose depth direction is a direction (horizontal direction) parallel to the surface of the wafer 200 may be removed. Further, the native oxide film on the third surface of the wafer 200 may be removed. Specifically, the native oxide film on the third surface constituted by the SiN film, which is the surface of a portion of the wafer 200 other than the recess, may be removed. Further, since the fourth surface of the wafer 200 is constituted by the SiO film, a native oxide film is not formed on the fourth surface, but in a case where a native oxide film is formed on the fourth surface for some reason, the native oxide film may also be removed.
A process condition when the etching agent is supplied in step F is exemplified as follows:
In the present disclosure, the notation of a numerical range such as “25 to 200 degrees C.” means that a lower limit value and an upper limit value thereof are included in the range. Therefore, for example, “25 to 200 degrees C.” means “25 degrees C. or higher and 200 degrees C. or lower.” The same applies to other numerical ranges. In the present disclosure, the processing temperature means the temperature of the wafer 200 or the internal temperature of the process chamber 201, and the processing pressure means the internal pressure of the process chamber 201. Further, the gas supply flow rate of 0 slm means a case where no gas is supplied. These apply equally to the following description.
After the native oxide film formed on the surface of the wafer 200 is removed, the valve 243e is closed to stop the supply of the etching agent into the process chamber 201. Then, the interior of the process chamber 201 is vacuum-exhausted to remove a gaseous substance and the like remaining in the process chamber 201 from the process chamber 201. At this time, the valves 243f to 243h are opened to allow an inert gas to be supplied into the process chamber 201 via the nozzles 249a to 249c. The inert gas supplied from the nozzles 249a to 249c acts as a purge gas, whereby the interior of the process chamber 201 is purged (purging).
A process condition when the purging is performed in step F is exemplified as follows:
As the etching agent, for example, a fluorine (F)-containing gas may be used. As the F-containing gas, for example, a chlorine trifluoride (ClF3) gas, a chlorine fluoride (ClF) gas, a nitrogen fluoride (NF3) gas, a hydrogen fluoride (HF) gas, a fluorine (F2) gas, or the like may be used. Various cleaning liquids may also be used as the etching agent. For example, DHF cleaning may be performed by using a HF aqueous solution as the etching agent. Further, for example, SC-1 cleaning (APM cleaning) may be performed by using a cleaning liquid containing ammonia water, hydrogen peroxide water, and pure water as the etching agent. Further, for example, SC-2 cleaning (HPM cleaning) may be performed by using a cleaning liquid containing hydrochloric acid, hydrogen peroxide water, and pure water as the etching agent. Further, for example, SPM cleaning may be performed by using a cleaning liquid containing sulfuric acid and hydrogen peroxide water as the etching agent. One or more selected from the group of these gases and liquids may be used as the etching agent.
As the inert gas, a nitrogen (N2) gas or a rare gas such as an argon (Ar) gas, a helium (He) gas, a neon (Ne) gas, or a xenon (Xe) gas can be used. This point also applies to each step described below. One or more selected from the group of these gases may be used as the inert gas.
Thereafter, step A1 of exciting an oxidizing agent and a reducing agent into a plasma state and supplying them to the wafer 200 and step A2 of exciting a reducing agent into a plasma state and supplying it to the wafer 200 are sequentially performed.
In step A1, the oxidizing agent and the reducing agent are excited into the plasma state and supplied to the wafer 200.
Specifically, the valves 243e and 243b are opened to allow the oxidizing agent and the reducing agent to flow through the gas supply pipes 232e and 232b, respectively. Flow rates of the oxidizing agent and the reducing agent are regulated by the MFCs 241e and 241b, respectively, mixed in the gas supply pipe 232b, excited into the plasma state by the RPU 300, supplied into the process chamber 201 via the nozzle 249b, and exhausted via the exhaust port 231a. In this operation, the oxidizing agent and the reducing agent excited into the plasma state are supplied to the wafer 200 from the side of the wafer 200 (oxidizing agent*+reducing agent*supply). In this way, it is possible to excite the oxidizing agent and the reducing agent into the plasma state and supply them to the wafer 200, thereby supplying oxygen (O)-containing radicals, hydrogen (H)-containing radicals, and the like to the wafer 200. These radicals may include O radicals, H radicals, and OH radicals. The treatment by using the oxidizing agent and the reducing agent excited into the plasma state may also include at least one selected from the group of plasma oxidation treatment, oxidizing agent plasma treatment (oxygen plasma treatment, etc.), plasma reduction treatment, reducing agent plasma treatment (hydrogen plasma treatment), and plasma oxidation-reduction treatment. In this operation, the valves 243f to 243h may be opened to allow an inert gas to be supplied into the process chamber 201 via the nozzles 249a to 249c, respectively, or the inert gas may not be supplied.
By exciting the oxidizing agent and the reducing agent into the plasma state and supplying them to the wafer 200 under process conditions described below, an OH termination may be formed on the first surface and the second surface of the wafer 200 after the native oxide film is removed. More specifically, the OH termination may be formed on the first surface, the second surface, and at least one selected from the group of the third surface and the fourth surface of the wafer 200 after the native oxide film is removed. In the embodiments of the present disclosure, the OH termination may be formed on the first surface, the second surface, and the third surface of the wafer 200 after the native oxide film is removed. Since the fourth surface is constituted by the SiO film, a sufficient amount of OH termination is formed on the fourth surface before this step is performed. However, in a case such as when the OH termination on the fourth surface is insufficient, the OH termination on the fourth surface may be reinforced in this step. Accordingly, in the embodiments of the present disclosure, by performing this step, the OH termination may be formed on each of the first surface, the second surface, the third surface, and the fourth surface of the wafer 200 after the native oxide film is removed (each surface may contain the OH termination).
That is, by exciting the oxidizing agent and the reducing agent into the plasma state and supplying them to the wafer 200 under process conditions described below, the first surface and the second surface of the wafer 200 after the native oxide film is removed may be oxidized (plasma-oxidized). More specifically, the first surface, the second surface, and at least one selected from the group of the third surface and the fourth surface of the wafer 200 after the native oxide film is removed may be oxidized. In the embodiments of the present disclosure, the first surface, the second surface, and the third surface of the wafer 200 after the native oxide film is removed may be oxidized. Since the fourth surface is constituted by the SiO film, the fourth surface is not be oxidized. However, in a case where the fourth surface contains an oxidizable element, the fourth surface may also be oxidized. Accordingly, in the embodiments of the present disclosure, by performing this step, each of the first surface, the second surface, the third surface, and the fourth surface of the wafer 200 after the native oxide film is removed may be oxidized (each surface may contain an oxide). As a result, an OH termination may be formed on each of the first surface, the second surface, the third surface, and the fourth surface of the wafer 200 after the native oxide film is removed (each surface may contain the OH termination). Further, as described above, the oxide formed on the first surface, the second surface, and the third surface of the wafer 200 are constituted by a very thin, uniform, and layer-like or film-like material.
Further, by performing this step, an oxide film (oxide) such as a silicon oxide film (SiO film), a germanium oxide film (GeO film), or a silicon germanium oxide film (SiGeO film) is formed on the first surface constituted by the SiGe film, and an OH termination is formed on the surface of the oxide film. Further, an oxide film (oxide) such as a SiO film is formed on the second surface constituted by the Si film, and an OH termination is formed on a surface of the oxide film. Further, an oxide film (oxide) such as a SiO film or a silicon oxynitride film (SiON film) is formed on the third surface constituted by the SiN film, and an OH termination is formed on a surface of the oxide film. The fourth surface constituted by the SiO film is maintained in such a state, and the state in which the OH termination is formed on the fourth surface is maintained, or the OH termination on the fourth surface is reinforced.
A process condition when the oxidizing agent and the reducing agent are excited into the plasma state and supplied in step A1 is exemplified as follows:
In the state where the OH termination is formed on the first surface, the second surface, and the third surface of the wafer 200 and the OH termination is formed on each of the first surface, the second surface, the third surface, and the fourth surface of the wafer 200, the valves 243e and 243b are closed to stop the supply of the oxidizing agent and the reducing agent into the process chamber 201. Then, a gaseous substance and the like remaining in the process chamber 201 are removed from the process chamber 201 (purging) according to the same processing procedure and process conditions as the purging in step F. The processing temperature when the purging is performed may be the same as the processing temperature when the oxidizing agent and the reducing agent are excited into the plasma state and supplied.
As the oxidizing agent, for example, an oxygen (O)-containing gas may be used. Examples of the O-containing gas may include an oxygen (O2) gas, an ozone (O3) gas, water vapor (H2O gas), a hydrogen peroxide (H2O2) gas, a nitrous oxide (N2O) gas, a nitric oxide (NO) gas, a nitrogen dioxide (NO2) gas, a carbon monoxide (CO) gas, a carbon dioxide (CO2) gas, and the like. One or more selected from the group of these gases may be used as the oxidizing agent.
As the reducing agent, for example, a hydrogen (H)-containing gas such as hydrogen (H2) gas or a deuterium (D)-containing gas such as a deuterium (D2) gas may be used. One or more selected from the group of these gases may be used as the reducing agent. This point also applies to step A2 described below.
After step A1 is completed, step A2 is performed. In step A2, a reducing agent is excited into a plasma state and supplied to the wafer 200.
Specifically, the valve 243b is opened to allow the reducing agent to flow through the gas supply pipe 232b. A flow rate of the reducing agent is regulated by the MFC 241b, excited into a plasma state by the RPU 300, supplied into the process chamber 201 via the nozzle 249b, and exhausted via the exhaust port 231a. In this operation, the reducing agent excited into the plasma state is supplied to the wafer 200 from the side of the wafer 200 (reducing agent*supply). In this way, it is possible to excite the reducing agent into the plasma state and supply it to the wafer 200, thereby supplying hydrogen (H)-containing radicals to the wafer 200. The H-containing radicals may include H radicals. The treatment in which the reducing agent excited into the plasma state is used may also include at least one selected from the group of plasma reduction treatment and reducing agent plasma treatment (hydrogen plasma treatment). At this time, the valves 243f to 243h may be opened to allow an inert gas to be supplied into the process chamber 201 via the nozzles 249a to 249c, respectively, or the inert gas may not be supplied.
By exciting the reducing agent into the plasma state and supplying it to the wafer 200 under process conditions described below, the first surface and the second surface of the wafer 200 on which the OH termination is formed may be modified by plasma treatment in which the reducing agent*is used. More specifically, the first surface, the second surface, and at least one selected from the group of the third surface and the fourth surface of the wafer 200 on which the OH termination is formed may be modified by plasma treatment in which the reducing agent* is used. In the embodiments of the present disclosure, each of the first surface, the second surface, the third surface, and the fourth surface of the wafer 200 in a state where the OH termination is formed (a state in which the OH termination is contained) may be modified by plasma treatment in which the reducing agent* is used. As a result, impurities such as carbon (C) and nitrogen (N) that may be contained in each surface may be removed, thereby increasing purity of the oxide film (oxide) on each surface and thus improving a state of OH termination. As a result, density of OH termination (Si—OH termination) on each surface may be increased, thereby creating a state in which each surface contains the high-density OH termination. That is, by performing step A1 and step A2, it is possible to create a state in which each of the first surface, the second surface, the third surface, and the fourth surface of the wafer 200 contain the high-density OH termination.
At this time, since an oxide film (oxide) is formed on each surface, each surface is not directly exposed to the plasma-excited reducing agent, that is, H-containing radicals, and thus it is possible to prevent plasma damage to a base (SiGe film, Si film, SiN film, or SiO film) constituting each surface. Further, when performing step A2 before performing step A1, since an oxide film (oxide) is not formed on each surface when step A2 is performed, each surface is directly exposed to the plasma-excited reducing agent, that is, H-containing radicals. As a result, the base (SiGe film, Si film, SiN film, or SiO film) constituting each surface may suffer plasma damage. In particular, the Si film constituting the second surface tends to be more susceptible to plasma damage than the other surfaces, and its shape may change when exposed to H-containing radicals. In contrast, according to the embodiments of the present disclosure, the oxide film (oxide) formed on each surface in step A1 acts as a protective film (block film or barrier film), which makes it possible to prevent the base (SiGe film, Si film, SiN film, or SiO film) constituting each surface from being damaged by plasma.
A process condition when the reducing agent is excited into the plasma state and supplied in step A2 is exemplified as follows:
After each of the first surface, the second surface, the third surface, and the fourth surface of the wafer 200 in the state of containing the OH termination is modified by plasma treatment in which the reducing agent* is used, the valve 243b is closed to stop the supply of the reducing agent into the process chamber 201. Then, a gaseous substance and the like remaining in the process chamber 201 are removed from the process chamber 201 (purging) according to the same processing procedure and process condition as the purging in step F. The processing temperature when the purging is performed may be the same as the processing temperature when the reducing agent is excited into the plasma state and supplied.
As the reducing agent, for example, the same reducing agents as the various reducing agents exemplified in the aforementioned step A1 may be used.
After step A is completed, step B is performed. In step B, heat treatment (annealing) is performed on the wafer 200 subjected to step A. Further, in step B, an output of the heater 207 is regulated such that the temperature of the wafer 200 is equal to or higher than the temperature of the wafer 200 in step A, specifically higher than the temperature of the wafer 200 in step A, and that state is maintained.
Specifically, for example, as shown in
Further, as shown in
In this case, the valves 243f to 243h are opened to allow the inert gas to flow through the gas supply pipes 232a to 232c, respectively. The flow rate of the inert gas is regulated by the MFCs 241f to 241h, and the inert gas is supplied into the process chamber 201 via the nozzles 249a to 249c and is exhausted via the exhaust port 231a. In this operation, the inert gas is supplied to the wafer 200 from the side of the wafer 200. However, the inert gas may not be supplied into the process chamber 201 in step B after the purging performed after step A (step A2) is sufficiently performed.
By performing the heat treatment on the wafer 200 under the process conditions described below, the OH termination formed on the first surface of the wafer 200 may be removed while leaving the high-density OH termination formed on the second surface of the wafer 200. More specifically, the OH termination formed on the first surface of the wafer 200 may be removed while leaving the high-density OH termination formed on the second surface and at least one selected from the group of the third surface and the fourth surface of the wafer 200. In the embodiments of the present disclosure, the OH termination formed on the first surface of the wafer 200 may be removed while maintaining a state in which the high-density OH termination is formed on each of the second surface, the third surface, and the fourth surface (each surface contains the high-density OH termination) of the wafer 200. In some cases, the OH terminations formed on the first surface of the wafer 200 may not be removed completely, and a small portion thereof may remain.
That is, by performing the heat treatment on the wafer 200 under process conditions described below, the oxide (GeO film or the like) formed on the first surface of the wafer 200 may be sublimated to be removed while leaving the oxide formed on the second surface of the wafer 200. More specifically, the oxide formed on the first surface of the wafer 200 may be sublimated to be removed while leaving the oxide formed on the second surface and at least one selected from the group of the third surface and the fourth surface of the wafer 200. In the embodiments of the present disclosure, the oxide formed on the first surface of the wafer 200 may be sublimated to be removed while maintaining a state in which each of the second surface, the third surface, and the fourth surface of the wafer 200 is oxidized (a state in which each surface contains the oxide). In some cases, the oxides formed on the first surface of the wafer 200 may not be removed completely, and a portion thereof may remain.
The reason why the oxide formed on the first surface among the first surface, the second surface, the third surface, and the fourth surface of the wafer 200 may be selectively sublimated to be removed in this way is that the oxide such as the GeO film formed on the first surface is easier to be sublimated than the oxide formed on the second surface, the third surface, and the fourth surface under process conditions described below. Under the process conditions described below, it is possible to sublimate the oxide such as the GeO film formed on the first surface and prevent the oxide formed on the second surface, the third surface, and the fourth surface from being sublimated. That is, under the process conditions described below, it is also possible to perform the heat treatment under the process conditions that the oxide such as the GeO film formed on the first surface is sublimated and the oxide formed on the second surface, the third surface, and the fourth surface is not sublimated.
The high-density OH termination on the second surface, the third surface, and the fourth surface may be left by leaving (maintaining) the oxide on the second surface, the third surface, and the fourth surface of the wafer 200, and the OH termination on the first surface may be removed by sublimating and removing the oxide on the first surface of the wafer 200. As a result, the second surface, the third surface, and the fourth surface before performing step C contain the high-density OH termination. On the other hand, the first surface before performing step C contains no OH termination or an OH termination of an amount much less than an amount of OH termination in the second surface, the third surface, and the fourth surface. That is, the amount (density or concentration) of OH termination on the second surface, the third surface, and the fourth surface before performing step C may be larger (higher) than the amount (density or concentration) of OH termination on the first surface. Further, the amount (density or concentration) of OH termination on the first surface may be zero.
A process condition when the heat treatment is performed on the wafer 200 in step B is exemplified as follows:
In a case where the heat treatment temperature is lower than 100 degrees C., the oxide formed on the first surface of the wafer 200 may not be sufficiently sublimated, such that the oxide may not be sufficiently removed. By setting the heat treatment temperature to 100 degrees C. or higher, the oxide formed on the first surface of the wafer 200 may be sufficiently sublimated to be sufficiently removed.
In a case where the heat treatment temperature exceeds 400 degrees C., at least a portion of the OH termination on the second surface, the third surface, and the fourth surface of the wafer 200 may be desorbed to be removed, such that the density of the OH termination on these surfaces may be reduced. In this case, in step C, the film formation inhibiting effect (adsorption inhibiting effect or reaction inhibiting effect) by an inhibitor layer formed on the second surface, the third surface, and the fourth surface of the wafer 200 is reduced, such that selectivity in selective growth in step D may be reduced. By setting the heat treatment temperature to 400 degrees C. or lower, it is possible to sufficiently suppress desorption and removal of the OH termination on the second surface, the third surface, and the fourth surface of the wafer 200, thereby sufficiently suppressing the density reduction of the OH termination on these surfaces. In this case, in step C, the film formation inhibiting effect by the inhibitor layer formed on the second surface, the third surface, and the fourth surface of the wafer 200 may be sufficiently obtained, such that selectivity in selective growth in step D may be sufficiently secured. By setting the heat treatment temperature to 350 degrees C. or lower, it is possible to effectively suppress the desorption and removal of the OH termination on the second surface, the third surface, and the fourth surface of the wafer 200, thereby effectively suppressing the density reduction of the OH termination on these surfaces. By setting the heat treatment temperature to 300 degrees C. or less, it is possible to more effectively suppress the desorption and removal of the OH termination on the second surface, the third surface, and the fourth surface of the wafer 200, thereby more effectively suppressing the density reduction of the OH termination on these surfaces.
From these things, in step B, it is desirable that the heat treatment temperature is set to 100 degrees C. or higher and 400 degrees C. or lower, specifically 100 degrees C. or higher and 350 degrees C. or lower, more specifically 100 degrees C. or higher and 300 degrees C. or lower.
After removing the OH termination formed on the first surface of the wafer 200 while maintaining the state in which each of the second surface, the third surface, and the fourth surface of the wafer 200 contains the OH termination, a gaseous substance and the like remaining in the process chamber 201 are removed from the process chamber 201 (purging) according to the same processing procedure and process condition as the purging in step F. The processing temperature when the purging is performed may be the same as the processing temperature when the heat treatment is performed on the wafer 200, but may be different from the processing temperature when the heat treatment is performed on the wafer 200.
After step B is completed, step C is performed. In step C, a modifying agent is supplied to the wafer 200 subjected to step B.
Specifically, the valve 243a is opened to allow the modifying agent to flow through the gas supply pipe 232a. A flow rate of the modifying agent is regulated by the MFC 241a, and the modifying agent is supplied into the process chamber 201 via the nozzle 249a and is exhausted via the exhaust port 231a. In this operation, the modifying agent is supplied to the wafer 200 from the side of the wafer 200 (modifying agent supply). At this time, the valves 243f to 243h may be opened to allow an inert gas to be supplied into the process chamber 201 via the nozzles 249a to 249c, respectively. Further, in step C, the output of the heater 207 is regulated such that the temperature of the wafer 200 is equal to or lower than the temperature of the wafer 200 in step B, specifically lower than the temperature of the wafer 200 in step B, and that state is maintained.
By supplying the modifying agent to the wafer 200 under process conditions described below, as shown in
The inhibitor layer formed in this step contains at least a portion of the molecular structure of the molecules constituting the modifying agent, which are residues derived from the modifying agent. The inhibitor layer prevents adsorption of a precursor (film-forming agent) on the second surface, the third surface, and the fourth surface to inhibit (suppress) progress of the film-forming reaction on the second surface, the third surface, and the fourth surface in step D described below.
As at least the portion of the molecular structure of the molecules constituting the modifying agent, for example, a trialkylsilyl group such as a trimethylsilyl group (Si-Me3) or a triethylsilyl group (Si-Et3) may be exemplified. The trialkylsilyl group contains an alkyl group, that is, a hydrocarbon group. In these cases, Si of the trimethylsilyl group or the triethylsilyl group is chemisorbed on the second surface, the third surface, and the fourth surface of the wafer 200 at a high density, such that the outermost surface of the second surface, the third surface, and the fourth surface is terminated with an alkyl group such as a methyl group or an ethyl group, that is, with a hydrocarbon group, at a high density. The alkyl group (alkylsilyl group) such as the methyl group (trimethylsilyl group) or the ethyl group (triethylsilyl group), that is, the hydrocarbon group, which terminates the second surface, the third surface, and the fourth surface at the high density, prevents adsorption of a precursor on the second surface, the third surface, and the fourth surface in a film-forming process (selective growth) described below, thereby acting as an inhibitor layer (film formation inhibition layer, adsorption inhibition layer, or reaction inhibition layer) that inhibits the progress of the film formation reaction on the second surface, the third surface, and the fourth surface.
Further, in this step, at least the portion of the molecular structure of the molecules constituting the modifying agent may be adsorbed on a portion of the first surface of the wafer 200 but an adsorption amount thereof is very small, and an adsorption amount thereof on the second surface, the third surface, and the fourth surface of the wafer 200 is overwhelmingly large. Such selective (preferential) adsorption is possible because the process condition in this step is a condition that the modifying agent does not undergo gas phase decomposition in the process chamber 201. This is also possible because the second surface, the third surface, and the fourth surface are OH-terminated at the high density over the entire region, whereas many regions on the first surface are not OH-terminated. In this step, since the modifying agent does not undergo the gas phase decomposition in the process chamber 201, at least a portion of the molecular structure of the molecules constituting the modifying agent is not multiple-deposited on the first surface, the second surface, the third surface, and the fourth surface, and at least a portion of the molecular structure of the molecules constituting the modifying agent is selectively adsorbed on the second surface, the third surface, and the fourth surface at a high density, whereby the second surface, the third surface, and the fourth surface are selectively terminated at a high density with at least the portion of the molecular structure of the molecules constituting the modifying agent.
A process condition when the modifying agent is supplied in step C is exemplified as follows:
After selectively forming the inhibitor layer on the second surface, the third surface, and the fourth surface of the wafer 200 at a high density, the valve 243a is closed to stop the supply of the modifying agent into the process chamber 201. Then, a gaseous substance and the like remaining in the process chamber 201 are removed from the process chamber 201 (purging) according to the same processing procedure and process condition as in the purging in step F. The processing temperature when the purging is performed may be the same as the processing temperature when the modifying agent is supplied.
As the modifying agent, for example, a compound containing a structure in which an amino group is directly bonded to Si or a compound containing a structure in which an amino group and an alkyl group are directly bonded to Si may be used.
Examples of the modifying agent may include (dimethylamino)silane ((CH3)2NSiH3), (diethylamino)silane ((C2H5)2NSiH3), (dipropylamino)silane ((C3H7)2NSiH3), (dibutylamino)silane ((C4H9)2NSiH3), (dimethylamino)trimethylsilane ((CH3)2NSi(CH3)3), (diethylamino)triethylsilane ((C2H5)2NSi(C2H5)3), (dimethylamino)triethylsilane ((CH3)2NSi(C2H5)3), (diethylamino)trimethylsilane ((C2H5)2NSi(CH3)3), (dipropylamino)trimethylsilane ((C3H7)2NSi(CH3)3), (dibutylamino)trimethylsilane ((C4H9)2NSi(CH3)3), (trimethylsilyl)amine ((CH3)3SiNH2), (triethylsilyl)amine ((C2H5)3SiNH2), and the like. Further, examples of the modifying agent may include bis(dimethylamino)dimethylsilane ([(CH3)2N]2Si(CH3)2), bis(diethylamino)diethylsilane ([(C2H5)2N]2Si(C2H5)2), bis(dimethylamino)diethylsilane ([(CH3)2N]2Si(C2H5)2), bis(diethylamino)dimethylsilane ([(C2H5)2N]2Si(CH3)2), bis(dimethylamino)silane ([(CH3)2N]2SiH2), bis(diethylamino)silane ([(C2H5)2N]2SiH2), bis(dimethylaminodimethylsilyl)ethane ([(CH3)2N(CH3)2Si]2C2H6), bis(dipropylamino)silane ([(C3H7)2N]2SiH2), bis(dibutylamino)silane ([(C4H9)2N]2SiH2), bis(dipropylamino)dimethylsilane ([(C3H7)2N]2Si(CH3)2), bis(dipropylamino)diethylsilane ([(C3H7)2N]2Si(C2H5)2), (dimethylsilyl)diamine ((CH3)2Si(NH2)2), (diethylsilyl)diamine ((C2H5)2Si(NH2)2), (dipropylsilyl)diamine ((C3H7)2Si(NH2)2), bis(dimethylaminodimethylsilyl)methane ([(CH3)2N(CH3)2Si]2CH2), bis(dimethylamino)tetramethyldisilane ([(CH3)2N]2(CH3)4Si2), and the like. One or more selected from the group of these may be used as the modifying agent.
After step C is completed, step D is performed. In step D, a film-forming agent is supplied to the wafer 200 subjected to step C. Further, in step D, the output of the heater 207 is regulated such that the temperature of the wafer 200 is equal to or lower than the temperature of the wafer 200 in step C, and while maintaining such a state, steps D1 and D2 are sequentially executed.
In step D1, a precursor (precursor gas) and a catalyst (catalyst gas) are supplied as a film-forming agent to the wafer 200 subjected to step C, that is, the wafer 200 after selectively forming the high-density inhibitor layer on the second surface, the third surface, and the fourth surface.
Specifically, the valves 243b and 243d are opened to allow the precursor and the catalyst to flow through the gas supply pipes 232b and 232d, respectively. Flow rates of the precursor and the catalyst are regulated by the MFCs 241b and 241d, respectively, and the precursor and the catalyst are supplied into the process chamber 201 via the nozzles 249b and 249a, respectively, mixed in the process chamber 201, and exhausted via the exhaust port 231a. In this operation, the precursor and the catalyst are supplied to the wafer 200 from the side of the wafer 200 (precursor+catalyst supply). In this operation, the valves 243f to 243h may be opened to allow an inert gas to be supplied into the process chamber 201 via the nozzles 249a to 249c, respectively.
By supplying the precursor and the catalyst to the wafer 200 under process conditions described below, it is possible to selectively (preferentially) chemisorb at least a portion of the molecular structure of molecules constituting the precursor on the first surface of the wafer 200 while suppressing chemisorption of at least the portion of the molecular structure of the molecules constituting the precursor on the second surface, the third surface, and the fourth surface of the wafer 200. As a result, a first layer is selectively (preferentially) formed on the first surface. The first layer contains at least a portion of the molecular structure of the molecules constituting the precursor, which are residues derived from the precursor. That is, the first layer contains at least a portion of atoms constituting the precursor.
In this step, by supplying the catalyst together with the precursor, the above-described reaction may be allowed to proceed under a non-plasma atmosphere and under a low temperature condition described below. In this way, by forming the first layer under the non-plasma atmosphere and under the low temperature condition as described below, it is possible to suppress removal and/or invalidation of the inhibitor layer formed on the second surface, the third surface, and the fourth surface of the wafer 200. The invalidation of the inhibitor layer means that the molecular structure of the molecules constituting the inhibitor layer, the arrangement structure of atoms constituting the inhibitor layer, etc. are changed to enable the adsorption of the film-forming agent on the second surface, the third surface, and the fourth surface of the wafer 200 or the reaction between the second surface/third surface/fourth surface and the film-forming agent.
Further, by forming the first layer under the non-plasma atmosphere and under the low temperature condition as described below, the precursor may be prevented from being thermally decomposed (gas phase-decomposed), that is, autolyzed, in the process chamber 201. As a result, it is possible to prevent multiple deposition of at least a portion of the molecular structure of molecules constituting the precursor on the first surface, the second surface, the third surface, and the fourth surface of the wafer 200 and cause the precursor to be selectively adsorbed on the first surface among the first surface, the second surface, the third surface, and the fourth surface of the wafer 200.
A process condition when the precursor and the catalyst are supplied in step D1 is exemplified as follows:
After selectively forming the first layer on the first surface of the wafer 200, the valves 243b and 243d are closed to stop the supply of the precursor and the catalyst, respectively, into the process chamber 201. Then, a gaseous substance and the like remaining in the process chamber 201 are removed from the process chamber 201 (purging) according to the same processing procedure and process condition as the purging in step F. The processing temperature when the purging is performed may be the same as the processing temperature when the precursor and the catalyst are supplied.
Further, in this step, when forming the first layer, at least a portion of the molecular structure of the molecules constituting the precursor may be adsorbed on portions of the second surface, the third surface, and the fourth surface of the wafer 200, but an adsorption amount thereof is very small and an adsorption amount thereof on the first surface of the wafer 200 is overwhelmingly large. Such selective (preferential) adsorption is possible because the process condition in this step is the low temperature condition and the condition that the precursor does not undergo vapor phase decomposition in the process chamber 201 as described above. Further, this is also possible because the high-density inhibitor layer is formed over the entire region of the second surface, the third surface, and the fourth surface of the wafer 200, whereas the inhibitor layer is not formed in many regions of the first surface of the wafer 200.
As the precursor, for example, a halosilane-based gas, that is, a Si- and halogen-containing gas (Si- and halogen-containing substance), may be used. The halogen includes chlorine (Cl), fluorine (F), bromine (Br), iodine (I), and the like. The Si- and halogen-containing gas may contain halogen in the form of a chemical bond between Si and halogen. As the Si- and halogen-containing gas, for example, a silane-based gas containing a Si—Cl bond, that is, a chlorosilane-based gas, may be used. The Si- and halogen-containing gas may further contain C, and in such a case, C may be contained in the form of a Si—C bond. As the Si- and halogen-containing gas, for example, a silane-based gas containing Si, Cl, and an alkylene group and containing a Si—C bond, that is, an alkylenechlorosilane-based gas, may be used. The alkylene group includes a methylene group, an ethylene group, a propylene group, a butylene group, and the like. Further, as the Si- and halogen-containing gas, for example, a silane-based gas containing Si, Cl, and an alkyl group and containing a Si—C bond, that is, an alkylchlorosilane-based gas, may be used. The alkyl group includes a methyl group, an ethyl group, a propyl group, a butyl group, and the like. The Si- and halogen-containing gas may further contain O, and in such a case, O may be contained in the form of a Si—O bond, for example in the form of a siloxane bond (Si—O—Si bond). As the Si- and halogen-containing gas, for example, a silane-based gas containing Si, Cl, and a siloxane bond, that is, a chlorosiloxane-based gas, may be used. These gases may contain Cl in the form of a Si—Cl bond. As the precursor, in addition to these gases, an amino group-containing gas (amino group-containing substance) such as an aminosilane-based gas may also be used.
Examples of the precursor may include 1,1,3,3-tetrachloro-1,3-disilacyclobutane (C2H4Cl4Si2), 1,1,2,2-tetrachloro-1,2-dimethyldisilane ((CH3)2Si2Cl4), 1,2-dichloro-1,1,2,2-tetramethyldisilane ((CH3)4Si2Cl2), bis(trichlorosilyl)methane ((SiCl3)2CH2), 1,2-bis(trichlorosilyl)ethane ((SiCl3)2C2H4), and the like. Further, examples of the precursor may include tetrachlorosilane (SiCl4), hexachlorodisilane (Si2Cl6), octachlorotrisilane (Si3Cl8), and the like. Further, examples of the precursor may include hexachlorodisiloxane (Cl3Si—O—SiCl3), octachlorotrisiloxane (Cl3Si—O—SiCl2—O—SiCl3), and the like. Further, examples of the precursor may include tetrakis(dimethylamino)silane (Si[N(CH3)2]4), tris(dimethylamino)silane (Si[N(CH3)2]3H), bis(diethylamino)silane (Si[N(C2H5)2]2H2), bis(tert-butylamino)silane (SiH2[NH(C4H9)]2), (diisopropylamino)silane (SiH3[N(C3H7)2]), and the like. One or more selected from the group of these gases may be used as the precursor.
As the catalyst, for example, an amine-based gas (amine-based substance) containing carbon (C), nitrogen (N), and hydrogen (H) may be used. As the amine-based gas (amine-based substance), a chain amine-based gas (chain amine-based substance) or a cyclic amine-based gas (cyclic amine-based substance) may be used. Examples of the catalyst may include chain amines such as triethylamine ((C2H5)3N), diethylamine ((C2H5)2NH), monoethylamine ((C2H5)NH2), trimethylamine ((CH3)3N), dimethylamine ((CH3)2NH), and monomethylamine ((CH3)NH2). Further, examples of the catalyst may include cyclic amines such as aminopyridine (C5H6N2), pyridine (C5H5N), picoline (C6H7N), lutidine (C7H9N), pyrimidine (C4H4N2), quinoline (C9H7N), piperazine (C4H10N2), piperidine (C5H11N), and aniline (C6H7N). One or more selected from the group of these may be used as the catalyst. This point also applies to a reactant supplying step described below.
In step D2, a reactant (reactant gas) and a catalyst (catalyst gas) are supplied as a film-forming agent to the wafer 200 subjected to step D1, that is, the wafer 200 with the first layer selectively formed on the first surface. Herein, an example in which an oxidizing agent (oxidizing gas) is used as a reactant (reacting gas) will be described.
Specifically, the valves 243c and 243d are opened to allow the reactant and the catalyst to flow through the gas supply pipes 232c and 232d, respectively. Flow rates of the reactant and the catalyst are regulated by the MFCs 241c and 241d, respectively, and the reactant and the catalyst are supplied into the process chamber 201 via the nozzles 249c and 249a, respectively, mixed in the process chamber 201, and exhausted via the exhaust port 231a. In this operation, the reactant and the catalyst are supplied to the wafer 200 from the side of the wafer 200 (reactant+catalyst supply). In this operation, the valves 243f to 243h may be opened to allow an inert gas to be supplied into the process chamber 201 via the nozzles 249a to 249c, respectively.
By supplying the reactant and the catalyst to the wafer 200 under process conditions described below, it is possible to oxidize at least a portion of the first layer formed on the first surface of the wafer 200 in step D1. As a result, a second layer formed by oxidizing the first layer is formed on the first surface.
In this step, by supplying the catalyst together with the reactant, the above-described reaction may proceed under a non-plasma atmosphere and under a low temperature condition as described below. In this way, by forming the second layer on the first surface under the non-plasma atmosphere and under the low temperature condition as described below, it is possible to suppress removal and/or invalidation of the inhibitor layer formed on the second surface, the third surface, and the fourth surface of the wafer 200.
A process condition when the reactant and the catalyst are supplied in step D2 is exemplified as follows:
After oxidizing the first layer formed on the first surface of the wafer 200 to change (convert) the first layer into the second layer, the valves 243c and 243d are closed to stop the supply of the reactant and the catalyst, respectively, into the process chamber 201. Then, a gaseous substance and the like remaining in the process chamber 201 are removed from the process chamber 201 (purging) according to the same processing procedure and process condition as the purging in step F. The processing temperature when the purging is performed may be the same as the processing temperature when the reactant and the catalyst are supplied.
As the reactant, for example, the same oxidizing agent as the various oxidizing agents exemplified in the above-described step A1 may be used. As the catalyst, for example, the same catalyst as the various catalysts exemplified in the above-described step D1 may be used.
By performing a cycle a predetermined number of times (n times, where n is 1 or an integer of 2 or more), the cycle including non-simultaneously, that is, alternatively without synchronization, performing the above-described steps D1 and D2, a film may be selectively (preferentially) grown on the first surface among the first surface, the second surface, the third surface, and the fourth surface of the wafer 200, to fill the recess with the film, as shown in
Further, by performing the above-described cycle a predetermined number of times, the film may be grown toward an opening side of the recess, starting from the bottom surface (the first surface) of the recess on the surface of the wafer 200. At this time, since the high-density inhibitor layer is formed on the second surface constituting the top surface and the side surface of the recess, it is possible to suppress the growth of the film starting from the second surface. Further, since the high-density inhibitor layer is also formed on the third surface and the fourth surface, which are the surfaces of portions of the surface of the wafer 200 other than the recess, it is also possible to suppress the growth of the film starting from the third surface and the fourth surface. That is, by performing the above-described cycle the predetermined number of times, it is possible to promote the growth of the film starting from the bottom surface of the recess, while suppressing the growth of the film starting from the top surface and the side surface of the recess and the surfaces of portions other than the recess. As a result, it is possible to grow the film in the bottom-up manner within the recess to fill the recess with the film, as shown in
Further, when performing steps D1 and D2, as shown in
After step D is completed, step E is performed. In step E, the wafer 200 is subjected to heat treatment (annealing) to perform post-treatment (PT) on the film formed to fill the recess. In this operation, the output of the heater 207 is regulated such that the internal temperature of the process chamber 201, that is, the temperature of the wafer 200 with the film formed to fill the recess, is equal to or higher than the temperature of the wafer 200 in steps A, B, C, and D, specifically higher than the temperature of the wafer 200 in these steps.
By performing the PT on the wafer 200, it is possible to remove/repair impurities/defects contained in the film formed to fill the recess, thereby hardening the film. By hardening the film, it is possible to improve a processing resistance of the film, that is, an etching resistance.
Further, by performing the PT on the wafer 200, as shown in
Further, this step may be performed in a state where an inert gas is supplied into the process chamber 201, or may be performed in a state where a reactive substance such as an oxidizing agent (oxidizing gas) is supplied into the process chamber 201. When a reactive substance such as an oxidizing agent is supplied, it is possible to effectively remove/repair impurities/defects contained in the film formed to fill the recess, and harden the film. Further, it is possible to enhance an effect of removing and/or invalidating the inhibitor layer on the interface between the side surface of the recess and the film, the other side surface of the recess, the top surface of the recess, and the surfaces of portions other than the recess. In this case, the inert gas and the reactive substance such as the oxidizing agent (oxidizing gas) are also referred to as an assistant substance. At this time, the assistant substance may be supplied after being excited into a plasma state, which makes it possible to further enhance the above-described effect.
A process condition when PT is performed in step E is exemplified as follows:
For the film formed to fill the recess, in a case where the removal of impurities, the repair of defects, or the hardening of the film may not be performed or in a case where the removal and/or the invalidation of the inhibitor layer may not be performed, step E may be omitted.
After step E is completed (after step D is completed in a case where step E is omitted), an inert gas acting as a purge gas is supplied into the process chamber 201 from each of the nozzles 249a to 249c and is exhausted via the exhaust port 231a. Thus, the interior of the process chamber 201 is purged and a gas, reaction by-products, and the like remaining in the process chamber 201 are removed from the process chamber 201 (after-purge). Thereafter, the internal atmosphere of the process chamber 201 is substituted with the inert gas (inert gas substitution) and the internal pressure of the process chamber 201 is returned to the atmospheric pressure (returning to atmospheric pressure).
Thereafter, the seal cap 219 is moved down by the boat elevator 115 to open the lower end of the manifold 209. Then, the processed wafers 200 supported by the boat 217 are unloaded from the lower end of the manifold 209 to the outside of the reaction tube 203 (boat unloading). After the boat unloading, the shutter 219s is moved and the lower end opening of the manifold 209 is sealed by the shutter 219s via the O-ring 220c (shutter closing). The processed wafers 200 are unloaded from the reaction tube 203 and are then discharged from the boat 217 (wafer discharging).
According to the embodiments of the present disclosure, one or more effects set forth below may be achieved.
Further, as described above, although the inhibitor layer is formed on the second surface, the third surface, and the fourth surface, the growth of a film starting from the second surface, the third surface, and the fourth surface may occur very slightly for some reason. In this case, a step of etching an extra film formed on the top surface (the second surface) of the recess and other surfaces (the third surface and the fourth surface) may be performed. However, even in such a case, since the extra film formed on the top surface of the recess and other surfaces (the third surface and the fourth surface) is very slight as described above, it is possible to greatly reduce a load in the step of etching the extra film, thereby greatly shortening an etching time.
On the other hand, when filling the recess with a film by a film-forming method such as performing step D in the related art, a film (SiOC) is formed on the entire side wall of the laminated structure in which the first material (SiGe) and the second material (Si) on the surface of the wafer 200 are alternately laminated, as shown in
In contrast, according to the embodiments of the present disclosure, as shown in
For these reasons, it is possible to effectively create a state in which the amount (density or concentration) of OH termination on each of the second surface, the third surface, and the fourth surface of the wafer 200 before performing step C is larger (higher) than an amount (density or concentration) of OH termination on the first surface of the wafer 200. Further, the amount (density or concentration) of OH termination on the first surface of the wafer 200 may be zero. Accordingly, in step C, it is possible to effectively cause at least a portion of the molecular structure of molecules constituting a modifying agent to be selectively (preferentially) adsorbed at a high density on the second surface, the third surface, and the fourth surface of the wafer 200, thereby selectively (preferentially) forming a high-density inhibitor layer on these surfaces. As a result, it is possible to fill the recess with the film with high selectivity while suppressing the growth of the film on the second surface, the third surface, and the fourth surface of the wafer 200. Further, in step B, by regulating the temperature of the wafer 200, that is, by heating the wafer 200 to a predetermined temperature, it is possible to selectively sublimate and remove an oxide formed on the first surface of the wafer 200 while leaving (maintaining) the OH termination on each of the second surface, the third surface, and the fourth surface of the wafer 200, thereby selectively removing the OH termination on the first surface.
Further, at this time, the assistant substance may be supplied after being excited into a plasma state. This makes it possible to further enhance the above-described effects.
The processing sequence in the embodiments of the present disclosure may be changed as in the following modifications. These modifications may be used in proper combination. Unless otherwise stated, a processing procedure and a process condition in each step of each modification may be the same as the processing procedure and process condition in each step of the above-described substrate processing sequence.
As in the processing sequence shown below, in step A, after performing steps A1 and A2, step A3 of exciting an oxidizing agent and a reducing agent into a plasma state and supplying them to the wafer 200 subjected to steps A1 and A2 may be further performed. In this case, step A further includes performing step A3. That is, step A includes performing step A1, step A2, and step A3. A processing procedure and a process condition in step A3 may be, for example, the same as those in the above-described step A1.
Oxidizing agent*+Reducing agent*→Reducing agent*→Oxidizing agent*+Reducing agent*→Heat treatment→Modifying agent→(Precursor→Reactant)×n
Oxidizing agent*+Reducing agent*→Reducing agent*→Oxidizing agent*+Reducing agent*→Heat treatment→Modifying agent→(Precursor+Catalyst→Reactant)×n
Oxidizing agent*+Reducing agent*→Reducing agent*→Oxidizing agent*+Reducing agent*→Heat treatment→Modifying agent→(Precursor→Reactant+Catalyst)×n
Oxidizing agent*+Reducing agent*→Reducing agent*→Oxidizing agent*+Reducing agent*→Heat treatment→Modifying agent→(Precursor+Catalyst→Reactant+Catalyst)×n
This modification may also obtain the same effects as in the above-described embodiments. Further, according to the modification, by adding step A3 in step A, it is possible to further increase the density of OH termination on the first surface, the second surface, the third surface, and the fourth surface of the wafer 200, thereby creating a state in which each surface contains a higher-density OH termination. As a result, in step C, it is possible to further increase the density of the inhibitor layer formed on the second surface, the third surface, and the fourth surface of the wafer 200, thereby further enhancing the film formation inhibiting effect (adsorption inhibiting effect or reaction inhibiting effect) of the inhibitor layer.
Depending on a surface condition of the wafer 200, step F (removal of native oxide film) may be omitted. For example, after the laminated structure including the first surface (surface of the SiGe film), the second surface (surface of the Si film), the third surface (surface of the SiN film), and the fourth surface (surface of the SiO film), as shown in
For the film formed to fill the recess, in a case where removal of impurities, repair of defects, and hardening of the film may not be performed or in a case where removal and/or invalidation of the inhibitor layer may not be performed on each surface of the wafer 200, step E may be omitted. For example, step E may be omitted when the amount of impurities, defects, and the like contained in the film formed to fill the recess is within an allowable range. Further, step E may be omitted even when an amount of residual groups or resides of an inhibitor layer on the interface between the side surface of the recess and the film, the other side surface of the recess, the top surface of the recess, and the surfaces of portions other than the recess is within an allowable range. Further, step E may be omitted when residual groups or residues of the inhibitor layer on the interface between the side surface of the recess and the film, the other side surface of the recess, the top surface of the recess, and the surfaces of portions other than the recess are removed by a reaction in the film-forming process or in a process after the film-forming process. This modification may also obtain the same effects as in the above-described embodiments. Further, by omitting step E, it is possible to shorten the total processing time, thereby improving the productivity.
The embodiments of the present disclosure are specifically described above. However, the present disclosure is not limited to the above-described embodiments, and various changes may be made without departing from the gist thereof.
For example, in step F, an etching agent may be excited into a plasma and supplied to the wafer 200. As a result, an etching rate when etching a native oxide film may be increased. Further, in step B, an inert gas may be excited into a plasma and supplied. This makes it possible to sublimate and remove an oxide such as GeO formed on the first surface and, at the same time, perform plasma treatment on the first surface after the oxide is removed. Further, in step E, an inert gas or an assistant substance may be excited into a plasma and supplied. This makes it possible to more effectively remove/repair impurities/defects contained in the film formed to fill the recess, and harden the film. Further, it is possible to further enhance the effect of removing and/or invalidating the inhibitor layer on the interface between the side surface of the recess and the film, the other side surface of the recess, the top surface of the recess, and the surfaces of portions other than the recess.
Further, for example, in step D, in addition to the SiOC film and the SiO film, a silicon-based oxide film such as a silicon oxycarbonitride film (SiOCN film), a silicon oxynitride film (SiON film), a silicon borooxynitride film (SiBON film), or a silicon borooxycarbonitride film (SiBOCN film) may be formed. Further, in step D, a metal-based oxide film such as an aluminum oxide film (AlO film), a titanium oxide film (TiO film), a hafnium oxide film (HfO film), or a zirconium oxide film (ZrO film) may be formed.
Recipes used in each process may be provided individually according to the processing contents and may be stored in the memory 121c via a telecommunication line or the external memory 123. Moreover, at the beginning of each process, the CPU 121a may properly select an appropriate recipe from the recipes recorded and stored in the memory 121c according to the processing contents. Thus, it is possible for a single substrate processing apparatus to form films of various kinds, composition ratios, qualities, and thicknesses with enhanced reproducibility. Further, it is possible to reduce an operator's burden and to quickly start each process while avoiding an operation error.
The recipes mentioned above are not limited to newly-provided ones but may be provided, for example, by modifying existing recipes that are already installed in the substrate processing apparatus. When the recipes are modified, the modified recipes may be installed in the substrate processing apparatus via a telecommunication line or a recording medium storing the recipes. In addition, the existing recipes already installed in the existing substrate processing apparatus may be directly modified by operating the input/output device 122 of the substrate processing apparatus.
An example in which the film is formed by using a batch-type substrate processing apparatus capable of processing a plurality of substrates at a time is described in the above-described embodiments. The present disclosure is not limited to the above-described embodiments, but may also be suitably applied, for example, to a case where a film is formed by using a single-wafer type substrate processing apparatus capable of processing a single substrate or several substrates at a time. In addition, an example in which the film is formed by using a substrate processing apparatus including a hot-wall-type process furnace is described in the above-described embodiments. The present disclosure is not limited to the above-described embodiments, but may also be suitably applied to a case where a film is formed by using a substrate processing apparatus including a cold-wall-type process furnace.
In the above-described embodiments of the present disclosure, an example in which step F and steps A to E are continuously performed (in-situ) in the same process chamber, that is, the same processor, of the same substrate processing apparatus (substrate processing system) is described. The present disclosure is not limited to the above-described embodiments, and may also be suitably applied to a case where, for example, as shown in
Further, the present disclosure may also be suitably applied to a case where, for example, as shown in
Even in the case of using these substrate processing systems and substrate processing apparatuses, the respective processes may be performed according to the same processing procedures and process conditions as those in the above-described embodiments, and the same effects as the above-described embodiments may be obtained.
The above-described embodiments may be used in proper combination. The processing procedures and process conditions used in this case may be the same as, for example, the processing procedures and process conditions in the above-described embodiments.
An evaluation sample 1 is provided by performing the processing sequence of the above-described embodiments on a wafer in which a laminated structure in which a SiGe film and a Si film are alternately laminated is formed on a surface of the wafer, a SiO film, a SiN film, and a SiO film are laminated on the laminated structure, and a recess whose top surface and side surface are constituted by the Si film, whose bottom surface is constituted by the SiGe film, and whose depth direction is a direction (horizontal direction) parallel to the surface of the wafer is formed in a side wall of the laminated structure including the SiGe film and the Si film to form a SiOC film so as to fill the recess, as shown in
An evaluation sample 2 is provided by performing the processing sequence in the above-described first modification on a wafer including the same structure as the wafer used when providing the evaluation sample 1 to form a SiOC film to fill the recess. Thereafter, a cross-sectional TEM image of the evaluation sample 2 is photographed. The cross-sectional TEM image of the evaluation sample 2 is shown in
As shown in
According to the present disclosure in some embodiments, it is possible to selectively form a film on a desired surface with high precision.
While certain embodiments are described above, these embodiments are presented by way of example, and are not intended to limit the scope of the disclosures. Indeed, the embodiments described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-152708 | Sep 2022 | JP | national |
