Substrate processing method and substrate processing device

Abstract

The present invention relates to a substrate processing method and a substrate processing apparatus. The substrate processing method processes a substrate having a metal layer on its main surface. The substrate processing method includes: a metal oxide layer forming step, in which an oxidizing fluid is supplied to the main surface of the substrate to form a metal oxide layer containing one or more atomic layers on the surface of the metal layer; and a metal oxide layer removal step, in which an etching fluid containing at least one of gaseous water and misted water, and a reactive gas that reacts with the metal oxide layer together with the water, is supplied to the main surface of the substrate to etch the metal oxide layer and selectively remove it from the substrate. Furthermore, by performing a cyclic process consisting of the metal oxide layer forming step and the metal oxide layer removal step as one cycle, the amount of metal layer etched is controlled with sub-nanometer accuracy in each cycle.

Description

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS]

[0002] This application corresponds to Japanese Patent Application No. 2021-28727 filed with the Japan Patent Office on February 25, 2021, and all disclosures of this application are incorporated herein by reference. Technical Field

[0003] The present invention relates to a substrate processing method and a substrate processing apparatus for processing a substrate. Examples of substrates to be processed include semiconductor wafers, FPD (Flat Panel Display) substrates such as liquid crystal display devices and organic EL (electroluminescence) display devices, optical disk substrates, magnetic disk substrates, magneto-optical disk substrates, photomask substrates, ceramic substrates, and solar cell substrates. Background Art

[0004] In the substrate processing disclosed in U.S. Patent Application Publication No. 2019 / 096721, to achieve sub-nanometer precision etching of a metal layer, a metal oxide layer formation step and a metal oxide layer removal step are repeatedly performed. The metal oxide layer formation step uses an oxidizing agent such as a hydrogen peroxide solution to oxidize the metal layer on the main surface of the substrate to form a metal oxide layer containing one or more atomic layers. The metal oxide layer removal step selectively removes the metal oxide layer using an etching solution such as dilute hydrofluoric acid. Between the metal oxide layer formation step and the metal oxide layer removal step, a rinsing step is performed using a rinsing solution capable of rinsing out the oxidizing agent or etching solution. Summary of the Invention

[0005] As in the substrate processing disclosed in the specification of U.S. Patent Application Publication No. 2019 / 096721, a method of etching a metal layer using a liquid in units of one atomic layer or several atomic layers is called ALWE (Atomic Layer Wet Etching). In ALWE, if the oxygen concentration (dissolved oxygen concentration) in the etching solution or the rinsing liquid is high, there is a concern that the oxygen in the etching solution will oxidize the metal layer and form an unintended oxidized metal layer. Therefore, in ALWE, in order to prevent the removal selectivity of the oxidized metal layer from decreasing, the dissolved oxygen in the etching solution or the rinsing liquid must be sufficiently reduced. Furthermore, in the case where the rinsing liquid or the etching solution is not distributed throughout the entire main surface of the substrate, there is a concern that uneven etching amounts will occur at various locations on the main surface of the substrate.

[0006] Therefore, an object of the present invention is to provide a substrate processing method and a substrate processing apparatus that can satisfactorily control the etching amount of a metal layer at each position on a main surface of a substrate with sub-nanometer accuracy.

[0007] One embodiment of the present invention is a substrate processing method for processing a substrate having a metal layer on its main surface. The substrate processing method includes: a metal oxide layer forming step in which an oxidizing fluid is supplied to the main surface of the substrate to form a metal oxide layer comprising one or more atomic layers on the surface of the metal layer; and a metal oxide layer removal step in which an etching fluid containing at least one of gaseous water and misted water, and a reactive gas that reacts with the metal oxide layer along with the water, is supplied to the main surface of the substrate to etch the metal oxide layer and selectively remove it from the substrate. Furthermore, by performing at least one cyclic process consisting of the metal oxide layer forming step and the metal oxide layer removal step as one cycle, the amount of metal layer etched can be controlled with sub-nanometer accuracy.

[0008] In this substrate processing method, in the metal oxide layer forming step, a metal oxide layer comprising one or several atomic layers is formed. The thickness of one atomic layer of metal and metal oxide is 1 nm or less (e.g., 0.3 nm or more and 0.4 nm or less). Several atomic layers refers to 2 to 10 atomic layers. Therefore, the thickness of the metal oxide layer is several nm or less (e.g., 5 nm or less).

[0009] Therefore, by selectively removing the metal oxide layer in the metal oxide layer removal step, a portion having a thickness of 5 nm or less from the metal layer surface can be etched. Furthermore, by performing a cyclic process consisting of the metal oxide layer formation step and the metal oxide layer removal step as one cycle at least once, the amount of metal layer etched can be controlled with sub-nanometer accuracy in each cycle. Sub-nanometer accuracy refers to accuracy of an index of nm (e.g., 5 nm) or less.

[0010] The thickness of the metal layer etched by one cycle of processing is substantially constant. Therefore, a desired etching amount can be achieved by adjusting the number of times the metal oxide layer forming step and the metal oxide layer removing step are repeated.

[0011] For example, if a metal layer is etched by 0.3 nm in one cycle, by adjusting the number of cycles, a base treatment can be performed to etch the metal layer by 1.5 nm, or a base treatment can be performed to etch the metal layer by 1.8 nm. In other words, the amount of metal layer etching can be controlled with an accuracy of approximately 0.3 nm.

[0012] In addition, in this substrate processing method, in order to selectively remove the oxidized metal layer, an etching fluid containing at least one of gaseous water (water vapor) and misted water and a reactive gas may be used.

[0013] Unlike this substrate processing method, when liquid water and a reactive liquid obtained by liquefying a reactive gas are supplied to the substrate's main surface in a continuous flow, the interface between these liquids and the substrate's main surface will be uneven. Consequently, at a molecular level, the frequency of collisions between the substrate's main surface and the molecules comprising the reactive liquid and reactive gas (hereinafter referred to as "reactive molecules") or water molecules will vary at various locations on the substrate's main surface.

[0014] Compared to a continuous stream of liquid water, gaseous or misted water diffuses more easily near the substrate's main surface. Similarly, reactive gases diffuse more easily near the substrate's main surface than reactive liquids. This facilitates uniform collision of water molecules and reactive molecules across the substrate's main surface. Therefore, using an etching fluid containing at least one of gaseous or misted water and a reactive gas makes it easier to suppress uneven etching of the substrate's main surface with subnanometer precision, compared to using an etching solution containing both liquid water and a reactive liquid.

[0015] As a result, the etching amount of the metal layer can be well controlled with a precision of nanometers or less at each position on the main surface of the substrate.

[0016] In one embodiment of the present invention, the substrate processing method further includes a reactive gas removal process, in which, after the metal oxide layer removal process, at least one of gaseous water and mist water is continuously supplied to the main surface of the substrate to remove the reactive gas from the space connected to the main surface of the substrate.

[0017] According to this substrate processing method, rather than completely replacing the etching fluid with another gas, reactive gases are removed from the space in contact with the substrate's main surface by continuously supplying at least one of gaseous water and misted water that constitute the etching fluid. This allows reactive gas components adhering to the substrate's main surface to be adsorbed by the water and rapidly removed.

[0018] In one embodiment of the present invention, the substrate processing method further includes a water removal process, which is performed after the reactive gas removal process, by replacing the water in the space connected to the main surface of the substrate with an inert gas, thereby removing water from the space connected to the main surface of the substrate.

[0019] According to this substrate processing method, water in the space adjacent to the substrate main surface is replaced with an inert gas and removed from the space, thereby suppressing unintended etching of the metal layer caused by a small amount of oxygen molecules adsorbed on water molecules.

[0020] In one embodiment of the present invention, the substrate processing method further includes an oxidizing fluid removal process, which is carried out after the metal oxide layer forming process and before the metal oxide layer removing process, by supplying an inert gas to the main surface of the substrate, thereby replacing the oxidizing fluid in the space connected to the main surface of the substrate with an inert gas, thereby removing the oxidizing fluid from the space connected to the main surface of the substrate.

[0021] According to this substrate processing method, the oxidizing fluid is removed from the space in contact with the substrate main surface before the oxidized metal layer removal step, thereby suppressing unintended oxidation of the metal layer during the oxidized metal layer removal step.

[0022] In one embodiment of the present invention, the metal oxide removal process includes: an etching fluid supply process, supplying etching fluid from an etching fluid supply unit to the main surface of the substrate; and a temperature adjustment process, adjusting the temperature of the substrate to a temperature lower than that of the etching fluid supplied from the etching fluid supply unit.

[0023] As a result, the temperature of the etching fluid decreases near the substrate's main surface, reducing the kinetic energy of the reactive molecules and water molecules near the substrate's main surface. This prevents reactive molecules and water molecules adsorbed on the substrate's main surface from leaving the substrate's main surface. In other words, this promotes the adsorption of reactive molecules and water molecules onto the substrate's main surface. This increases the etching rate of the metal layer. As a result, the etching amount per cycle of the cyclic treatment can be maintained at one or several atomic layers, while increasing the etching rate of the metal layer.

[0024] In one embodiment of the present invention, the metal oxide layer forming step includes a heated oxidation step in which the metal oxide layer is formed by supplying the oxidizing fluid to the main surface of the substrate while heating the substrate. The metal oxide layer removal step includes a low-temperature etching step in which the metal oxide layer is etched by supplying the etching fluid to the main surface of the substrate while the substrate temperature is lower than the substrate temperature in the metal oxide layer forming step.

[0025] According to this substrate processing method, when the substrate temperature is relatively high (e.g., 100°C to 400°C), the metal layer on the main surface of the substrate oxidizes. This increases the oxidation rate of the metal layer. On the other hand, etching is performed when the substrate temperature is relatively low (e.g., 25°C to 100°C). If the substrate temperature is relatively high, the small amount of oxygen molecules present in the etching fluid has oxidizing power. Therefore, by performing etching at a relatively low temperature, unintended oxidation of the metal layer during the oxidized metal layer removal step can be suppressed.

[0026] In one embodiment of the present invention, in the heated oxidation step, the substrate is heated by placing the substrate on a heating surface of a heating member disposed in a chamber while supplying the oxidizing fluid to the main surface of the substrate. In the low-temperature etching step, the temperature of the substrate is lowered by decreasing the temperature of the heating member while maintaining the substrate on the heating surface.

[0027] According to this substrate processing method, the substrate is both heated and cooled while being placed on the heating surface of a single heating element. Therefore, substrate processing can be simplified compared to a configuration in which the substrate is moved to a separate element from the heating element in order to change the substrate temperature.

[0028] In one embodiment of the present invention, in the heated oxidation step, the substrate is heated by placing the substrate on a temperature control surface of a first temperature control member disposed in a first chamber while supplying the oxidizing fluid to the main surface of the substrate. Furthermore, in the low-temperature etching step, the substrate temperature can be lowered by moving the substrate from the temperature control surface and placing the substrate on a second temperature control surface of a second temperature control member disposed in a second chamber and having a lower temperature than the first temperature control member.

[0029] According to this substrate processing method, substrate temperature regulation can be performed on the first temperature regulation surface of the first temperature regulation component and then on the second temperature regulation surface of the second temperature regulation component. In other words, temperature regulation is performed twice using different components. Therefore, compared to a configuration in which the substrate temperature is regulated by changing the temperature of the temperature regulation surface of a single temperature regulation component, the time required for substrate temperature regulation can be shortened.

[0030] In one embodiment of the present invention, the metal layer comprises a metal nitride layer containing a Group III metal. Group III metals refer to metals in Group 13 of the periodic table. Specifically, Group III metals include aluminum (Al), gallium (Ga), indium (In), and thallium (Tl). Metal nitrides containing Group III metals oxidize to form oxides that react with water and reactive gases.

[0031] For example, if the metal nitride layer is a gallium nitride (GaN) layer and the oxidizing fluid is ozone gas, then ozone molecules (O3) oxidize the gallium nitride to produce gallium oxide (Ga2O3), as shown in the following chemical reaction formula 1. Specifically, the ozone molecules are heated to generate oxygen radicals, which oxidize the gallium nitride.

[0032] [Chemistry 1]

[0033] [Chemistry 1]

[0034] 2GaN+O3→Ga2O3+N2

[0035] When the reactive gas contained in the etching fluid is ammonia (NH3), the reactions shown in the following chemical reaction formulas 2 and 3 occur. As shown in chemical reaction formula 2, gallium oxide reacts with hydroxide ions, dissolving the gallium oxide in the etching fluid and forming ions. Alternatively, as shown in chemical reaction formula 3, gallium oxide, water, and ammonia react, dissolving the gallium oxide in the etching fluid and forming ions.

[0036] [Chemistry 2]

[0037] [Chemistry 2]

[0038] Ga2O3+6OH-→2GaO3 3- +3H2O

[0039] [Chemistry 3]

[0040] [Chemistry 3]

[0041] Ga2O3+6NH3+6H2O→2GaO3 3- +6NH4 + +3H2O

[0042] When the reactive gas contained in the etching fluid is hydrogen chloride (HCl), the reactions shown in the following chemical reaction formulas 4 and 5 occur. As shown in chemical reaction formula 4, gallium oxide reacts with hydrogen chloride, dissolving the gallium oxide in the etching fluid and forming ions. Separately, as shown in chemical reaction formula 5, gallium oxide reacts with hydrogen chloride, dissolving the gallium oxide in the etching fluid and forming ions.

[0043] [Chemistry 4]

[0044] [Chemistry 4]

[0045] Ga2O3+6HCl→2GaCl3+3H2O

[0046] [Chemistry 5]

[0047] [Chemistry 5]

[0048] Ga2O3+6HCl→2Ga 3- +6Cl - +3H2O

[0049] In one embodiment of the present invention, the water contained in the etching fluid is vaporous water. When vaporous water is used in the metal oxide layer removal process, bulk water (in the form of microscopic droplets) is less likely to adhere to the substrate's main surface than when mist water is used. Therefore, using vaporous water as the water contained in the etching fluid allows water molecules to more uniformly impact various locations on the substrate's main surface.

[0050] Another embodiment of the present invention provides a substrate processing apparatus for processing a substrate having a metal layer on its main surface. The substrate processing apparatus includes: a temperature control component having a temperature control surface on which the substrate is placed, and regulating the temperature of the substrate placed on the temperature control surface to a predetermined first temperature and a second temperature lower than the first temperature; a chamber accommodating the temperature control component; an oxidizing fluid supply unit that supplies an oxidizing fluid into the chamber to form an oxidized metal layer containing one or more atomic layers on the surface of the metal layer; and an etching fluid supply unit that supplies an etching fluid containing at least one of gaseous water and misted water, and a reactive gas that reacts with the oxidized metal layer together with the water, into the chamber to selectively etch the oxidized metal layer.

[0051] According to this substrate processing apparatus, the oxidizing fluid supplied by the oxidizing fluid supply unit forms a metal oxide layer comprising one or more atomic layers. Therefore, by selectively removing the metal oxide layer using the etching fluid supplied by the etching fluid supply unit, it is possible to etch a portion of the metal layer with a thickness of less than 5 nm from the surface. By repeatedly forming the metal oxide layer using the oxidizing fluid supply unit and selectively removing the metal oxide layer using the etching fluid supply unit, the amount of metal layer etched can be controlled with sub-nanometer precision.

[0052] By performing the formation of the metal oxide layer using the oxidizing fluid supply unit and the selective removal of the metal oxide layer using the etching fluid supply unit once, the thickness of the etched metal layer is substantially constant. Therefore, the desired etching amount can be achieved by adjusting the number of times the formation of the metal oxide layer and the removal of the metal oxide layer are repeated.

[0053] Furthermore, in this substrate processing apparatus, an etching fluid containing at least one of gaseous water (water vapor) and misted water, along with a reactive gas, is used to selectively remove the metal oxide layer. As described above, this facilitates uniform collision of water molecules and reactive molecules across various locations on the substrate's main surface. Therefore, using an etching fluid containing at least one of gaseous water and misted water, along with a reactive gas, allows for sub-nanometer precision reduction in the amount of etching on the substrate's main surface, compared to using an etching fluid containing liquid water and a reactive liquid.

[0054] As a result, the etching amount of the metal layer can be well controlled with a precision of nanometers or less at each position on the main surface of the substrate.

[0055] In another embodiment of the present invention, the substrate processing apparatus includes a controller for controlling the oxidizing fluid supply unit and the etching fluid supply unit. The controller is programmed to execute: a metal oxide layer formation step in which the oxidizing fluid is supplied from the oxidizing fluid supply unit to the main surface of the substrate, thereby forming a metal oxide layer comprising one or more atomic layers on the surface of the metal layer; and a metal oxide layer removal step in which the etching fluid is supplied from the etching fluid supply unit to the main surface of the substrate, thereby selectively removing the metal oxide layer from the main surface of the substrate by etching. Furthermore, by executing at least one cyclic process consisting of the metal oxide layer formation step and the metal oxide layer removal step as one cycle, the amount of metal layer etched can be controlled with sub-nanometer accuracy in each cycle.

[0056] This substrate processing apparatus can automatically perform a desired number of cycles, each consisting of a metal oxide layer forming step and a metal oxide layer removing step. The thickness of the metal layer etched in each cycle is substantially constant. Therefore, the desired etching amount can be achieved by adjusting the number of times the metal oxide layer forming step and the metal oxide layer removing step are performed.

[0057] In another embodiment of the present invention, the etching fluid supply unit is configured to supply the etching fluid into the chamber via a fluid inlet port opened in the chamber, and the second temperature is lower than a temperature of the etching fluid introduced into the chamber via the fluid inlet port.

[0058] As a result, the temperature of the etching fluid decreases near the substrate's main surface, reducing the kinetic energy of the reactive molecules and water molecules near the substrate's main surface. This prevents reactive molecules and water molecules adsorbed on the substrate's main surface from leaving the substrate's main surface. In other words, this promotes the adsorption of reactive molecules and water molecules onto the substrate's main surface. This increases the etching rate of the metal layer. As a result, the etching amount per cycle of the cyclic treatment can be maintained at one or several atomic layers, while increasing the etching rate of the metal layer.

[0059] In another embodiment of the present invention, the temperature adjustment member is configured to have a single temperature adjustment surface, and adjust the temperature of the substrate to the first temperature and the second temperature when the substrate is placed on the single temperature adjustment surface.

[0060] This substrate processing apparatus can both heat and cool the substrate while placing it on a single temperature control surface. This simplifies substrate processing compared to a configuration in which the substrate is moved to a separate component from the heating component to change its temperature.

[0061] In another embodiment of the present invention, the temperature adjustment component includes: a first temperature adjustment component having a first temperature adjustment surface as the temperature adjustment surface, and adjusting the substrate placed on the first temperature adjustment surface to the first temperature; and a second temperature adjustment component having a second temperature adjustment surface as the temperature adjustment surface, and adjusting the substrate placed on the second temperature adjustment surface to the second temperature. The chamber includes a first chamber for accommodating the first temperature adjustment component and a second chamber for accommodating the second temperature adjustment component. Furthermore, the oxidizing fluid supply unit is configured to supply an oxidizing fluid into the first chamber, and the etching fluid supply unit is configured to supply an etching fluid into the second chamber.

[0062] According to this substrate processing apparatus, substrate temperature is regulated on the first temperature regulation surface of the first temperature regulation component and then on the second temperature regulation surface of the second temperature regulation component. In other words, temperature regulation is performed twice by different components. Therefore, compared to a configuration in which the substrate temperature is regulated by changing the temperature of the temperature regulation surface of a single temperature regulation component, the time required for substrate temperature regulation can be shortened.

[0063] In another embodiment of the present invention, the first temperature is greater than or equal to 100°C and less than or equal to 400°C, and the second temperature is greater than or equal to 25°C and less than or equal to 100°C. That is, when the temperature of the substrate is relatively high (e.g., greater than or equal to 100°C and less than or equal to 400°C), the metal layer on the main surface of the substrate oxidizes. Therefore, the oxidation rate of the metal layer can be increased. On the other hand, etching is performed when the temperature of the substrate is relatively low (e.g., greater than or equal to 25°C and less than or equal to 100°C). If the temperature of the substrate is relatively high, the small amount of oxygen molecules present in the etching fluid has oxidizing power. Therefore, by performing etching at a relatively low temperature, unintentional oxidation of the metal layer can be suppressed.

[0064] The above and other objects, features and effects of the present invention will become more apparent from the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1A It is a plan view for explaining the structure of the substrate processing apparatus according to the first embodiment of the present invention.

[0066] Figure 1B It is a schematic elevation view for explaining the structure of the substrate processing apparatus.

[0067] Figure 2 It is a schematic cross-sectional view for explaining a configuration example of a heat treatment unit included in the substrate processing apparatus.

[0068] Figure 3 It is a schematic diagram for explaining the situation when a substrate is carried in and out of a heat treatment unit included in the substrate processing apparatus.

[0069] Figure 4 This is a block diagram for explaining a configuration example related to control of the substrate processing apparatus.

[0070] Figure 5 This is a flowchart for explaining a specific substrate processing flow performed by the substrate processing apparatus.

[0071] Figure 6 FIG. 1 is a timing diagram of steps performed in a heat treatment chamber during substrate processing.

[0072] Figure 7 (a) to (g) are schematic diagrams for explaining changes in the substrate surface state caused by repeating the metal oxide layer forming step and the metal oxide layer removing step in the substrate processing.

[0073] Figure 8 is a schematic cross-sectional view of a modified example of the heat treatment unit.

[0074] Figure 9 It is a schematic cross-sectional view of a modified example of a processing unit included in the substrate processing apparatus.

[0075] Figure 10 It is a schematic cross-sectional view for explaining a configuration example of a first heat treatment unit included in the substrate processing apparatus according to the second embodiment.

[0076] Figure 11 It is a schematic cross-sectional view for explaining a configuration example of a second heat treatment unit included in the substrate processing apparatus according to the second embodiment.

[0077] Figure 12 This is a flowchart for explaining a specific substrate processing flow performed by the substrate processing apparatus according to the second embodiment. DETAILED DESCRIPTION

[0078] <First embodiment>

[0079] Figure 1A It is a plan view for explaining the structure of the substrate processing apparatus 1 according to the first embodiment of the present invention. Figure 1B It is a schematic elevation view for explaining the structure of the substrate processing apparatus 1 .

[0080] The substrate processing apparatus 1 is a single-wafer apparatus for processing substrates W such as silicon wafers one by one. In this embodiment, the substrate W is a disk-shaped substrate. The substrate W has, for example, a first main surface W1 (refer to FIG. 1 ) where a metal layer is exposed. Figure 1B ), and a second main surface W2 on the opposite side to the first main surface W1.

[0081] The metal layer exposed from the first main surface W1 is, for example, a metal nitride layer (metal nitride layer) containing a Group III metal. Group III metals are metals in Group 13 of the periodic table. Specifically, Group III metals include aluminum (Al), gallium (Ga), indium (In), and thallium (Tl).

[0082] The substrate processing apparatus 1 includes: a plurality of processing units 2 for processing substrates W using a processing fluid; a load port LP for receiving carriers C for accommodating a plurality of substrates W to be processed by the processing units 2; transfer robots IR and CR for transferring substrates W between the load port LP and the processing units 2; and a controller 3 for controlling the substrate processing apparatus 1.

[0083] The transfer robot IR transfers substrates W between the carrier C and the transfer robot CR. The transfer robot CR transfers substrates W between the transfer robot IR and the processing unit 2. The transfer robots IR and CR are arranged on a transfer path TR extending from a plurality of load ports LP to a plurality of processing units 2.

[0084] The multiple processing units 2 form four processing towers, each arranged at four horizontally spaced locations. Each processing tower includes multiple processing units 2 stacked vertically. Two of the four processing towers are located on each side of the transport path TR. In this embodiment, the processing units 2 are dry processing units that process the substrates W using a process gas such as an oxidizing gas or an etching gas, rather than supplying liquid to the substrates W.

[0085] The processing unit 2 includes a dry chamber 4 with a loading / unloading port 4a for substrates W to pass through, and a thermal processing unit 5 that heats the substrates W within the dry chamber 4 while supplying a processing gas to the substrates W. An openable and closable shutter 6 is provided at the loading / unloading port 4a. The hand H of the transfer robot CR places the substrates W in and out of the dry chamber 4 via the loading / unloading port 4a.

[0086] Figure 2 It is a schematic cross-sectional view for explaining a configuration example of the heat treatment unit 5 .

[0087] The heat treatment unit 5 includes: a heating plate 20 as a heating component; a heat treatment chamber 30 (chamber) that accommodates the heating plate 20; a plurality of lift pins 40 that pass through the heating plate 20 and move up and down; and a pin lifting drive mechanism 41 that moves the plurality of lift pins 40 in the up and down direction.

[0088] The heating plate 20 has a heating surface 20a on which a substrate W is placed. The heating plate 20 has a built-in heater 21. The heater 21 can heat the substrate W to a temperature substantially equal to the temperature of the heater 21. The heater 21 is configured to heat the substrate W placed on the heating surface 20a to a temperature within a range from room temperature (e.g., 25°C) to 400°C. Specifically, a power supply unit (not shown) is connected to the heater 21, and by adjusting the current supplied by the power supply unit, the temperature of the heater 21 becomes a temperature within the temperature range. The heating plate 20 is an example of a temperature control component, and the heating surface 20a is an example of a temperature control surface.

[0089] Heat treatment chamber 30 includes chamber body 31 and lid 32 that moves vertically above chamber body 31. Heat treatment unit 5 includes lid lift drive mechanism 33 that lifts lid 32 (moves it vertically).

[0090] The chamber body 31 has an opening that opens upward. Specifically, the chamber body 31 includes a support portion 34 that supports the heating plate 20, and a cylindrical portion 35 that extends upward from the periphery of the support portion 34. The support portion 34 has a generally circular shape when viewed from above, and the cylindrical portion 35 has a corresponding cylindrical shape. The cylindrical portion 35 forms the opening of the chamber body 31.

[0091] The lid 32 includes a flat plate portion 37 extending parallel to the heating surface 20a and a cylindrical portion 38 extending downward from the periphery of the flat plate portion 37. The flat plate portion 37 is generally circular in plan view, and the cylindrical portion 38 has a corresponding cylindrical shape. The lower end of the cylindrical portion 38 faces the upper end of the cylindrical portion 35 of the chamber body 31. Thus, the opening of the chamber body 31 can be opened and closed by moving the lid 32 up and down. The cylindrical portion 35 of the chamber body 31 and the cylindrical portion 38 of the lid 32 are sealed by an elastic member 39, such as an O-ring. The lower surface of the flat plate portion 37 is parallel to the heating surface 20a of the heating plate 20. More specifically, when a substrate W is placed on the heating surface 20a, a space is formed between the substrate W and the flat plate portion 37.

[0092] The cover 32 is in the lower position ( Figure 2 Position shown) and upper position (described below Figure 3 The lid 32 moves up and down between the positions shown in the figure. The lower position blocks the opening of the chamber body 31, forming a sealed processing space SP within, and the upper position allows the opening to be opened and retracted upward. When the lid 32 is in the lower position, the chamber body 31 and lid 32 are in contact. The sealed processing space SP is the space that contacts the upper surface of the substrate W. When the lid 32 is in the upper position, the hand H of the transfer robot CR can enter and exit the thermal processing chamber 30.

[0093] The cover lifting drive mechanism 33 may be an electric motor or an air cylinder, or an actuator other than these.

[0094] The plurality of lift pins 40 are connected by a connecting plate 43. The plurality of lift pins 40 are moved up and down by a pin lifting drive mechanism 41 so as to be in an upper position (hereinafter referred to as Figure 3 position) and the lower position ( Figure 2 The pin lift drive mechanism 41 can be an electric motor, an air cylinder, or any other actuator.

[0095] Multiple lift pins 40 are inserted into multiple through-holes 22 that penetrate the heating plate 20 and the chamber body 31. A bellows 42 surrounding the lift pins 40 prevents fluid from entering the through-holes 22 from outside the heat treatment chamber 30. The bellows 42 expands and contracts as the connecting plate 43 moves up and down, maintaining the airtightness of the space within the heat treatment chamber 30.

[0096] The lift pin 40 includes a hemispherical upper end portion that contacts the lower surface of the substrate W. The tip ends of the plurality of lift pins 40 are arranged at the same height.

[0097] The heat treatment unit 5 includes a plurality of fluid inlet ports 10 for introducing gas into the sealed processing space SP within the heat treatment chamber 30. Each fluid inlet port 10 is a through hole extending through the flat plate portion 37 of the lid 32. The plurality of fluid inlet ports 10 are spaced apart in the circumferential and radial directions of the flat plate portion 37.

[0098] The plurality of fluid inlet ports 10 include a plurality of first fluid inlet ports 10A connected to a first fluid line 50 for introducing an inert gas and an oxidizing gas, and a plurality of second fluid inlet ports 10B connected to a second fluid line 51 for introducing an inert gas and an etching gas. The first fluid line 50 and the second fluid line 51 are primarily composed of pipes.

[0099] The inert gas is, for example, nitrogen (N 2 ) gas. The inert gas is a gas that does not react with the metal nitride layer exposed from the first main surface W1 of the substrate W (is inert to the metal nitride layer).

[0100] The inert gas is not limited to nitrogen, and may be, for example, a rare gas such as argon (Ar) gas, or a mixed gas of nitrogen and a rare gas. In other words, the inert gas may be a gas containing at least one of nitrogen and a rare gas.

[0101] The oxidizing gas is, for example, ozone (O3) gas. The oxidizing gas oxidizes the metal nitride layer exposed from the first main surface W1 of the substrate W, forming a metal oxide layer (metal oxide layer). The oxidizing gas is not limited to ozone gas; for example, it may be oxidizing water vapor, O2, N2O, NO2, or a halogen gas such as F2 or Cl2. If the metal nitride layer is a gallium nitride layer, the metal nitride layer is oxidized by the oxidizing gas, forming a gallium oxide layer. The oxidizing gas is also called a gaseous oxidant.

[0102] The etching gas etches the metal oxide layer, removing it from the first main surface W1 of the substrate W. The etching gas is a mixture of water vapor and a reactive gas. The reactive gas is reactive with the metal oxide layer in the presence of water, such as ammonia (NH3) gas. The water vapor is preferably sufficiently heated, that is, superheated water vapor heated to 100°C or higher. The etching gas is an example of an etching fluid.

[0103] The metal oxide constituting the metal oxide layer reacts with the reactive gas and water vapor to generate metal hydroxide adsorbed on the water vapor. The metal hydroxide is adsorbed on the water vapor in the etching gas and removed from the upper surface of the substrate W.

[0104] The reactive gas is not limited to ammonia gas, and any gas containing a basic component that is alkaline in water or an acidic gas containing an acidic component that is acidic in water may be used. For example, ammonia gas may be selected as the basic gas.

[0105] The acid gas is typically hydrogen chloride (HCl) gas. The acid gas may also include at least one gas selected from hydrogen chloride gas, carbon dioxide gas, hydrogen sulfide (H2S) gas, and sulfur dioxide (SO2) gas.

[0106] Group III metals, like silicon (Si), can be used as materials for power devices. Unlike silicon carbide (SiC) crystals, Group III metal oxides formed on the surface of Group III metal nitride crystals react with alkaline or acidic components in the presence of water to form water-soluble hydroxides.

[0107] When the metal nitride layer is a gallium nitride layer, as shown in Chemical Reaction Formula 1, the gallium nitride constituting the gallium nitride layer reacts with ozone gas, an oxidizing gas, to produce gallium oxide (Ga2O3), which constitutes the gallium oxide layer, the metal oxide layer. When the reactive gas is ammonia gas, the gallium oxide constituting the gallium oxide layer reacts with the ammonia gas, thereby reacting with the ammonia, or with ammonia and water, as shown in Chemical Reaction Formulas 2 and 3. When the reactive gas contained in the etching fluid is hydrogen chloride gas, the gallium oxide reacts with hydrogen chloride, as shown in Chemical Reaction Formulas 4 and 5.

[0108] The first fluid line 50 is connected to a first inert gas line 52 for supplying an inert gas to the first fluid line 50 , and an oxidizing fluid line 53 for supplying an oxidizing gas to the first fluid line 50 .

[0109] The first inert gas line 52 is provided with a first inert gas valve 62A for opening and closing the flow path and a first inert gas flow rate regulating valve 62B for regulating the flow rate of the inert gas supplied to the first fluid line 50 .

[0110] The oxidizing fluid line 53 is provided with an oxidizing fluid valve 63A for opening and closing the flow path, and an oxidizing fluid flow regulating valve 63B for regulating the flow rate of the oxidizing gas supplied to the first fluid line 50 .

[0111] When the first inert gas valve 62A is opened, an inert gas is introduced into the sealed processing space SP from the plurality of first fluid introduction ports 10A, and the inert gas is supplied to the upper surface of the substrate W. When the oxidizing fluid valve 63A is opened, an oxidizing gas is introduced into the sealed processing space SP from the plurality of first fluid introduction ports 10A, and the oxidizing gas is supplied to the upper surface of the substrate W.

[0112] When both the first inert gas valve 62A and the oxidizing fluid valve 63A are opened, a mixed gas of an inert gas and an oxidizing gas is introduced into the sealed processing space SP through the plurality of first fluid inlet ports 10A. By adjusting the openings of the first inert gas flow control valve 62B and the oxidizing fluid flow control valve 63B, the concentration (partial pressure) of the oxidizing gas component in the mixed gas introduced into the sealed processing space SP through the plurality of first fluid inlet ports 10A can be adjusted.

[0113] The first fluid line 50 , the first inert gas line 52 , and the first inert gas valve 62A are examples of inert gas supply means. The first fluid line 50 , the oxidizing fluid line 53 , and the oxidizing fluid valve 63A are examples of oxidizing fluid supply means for supplying oxidizing fluid into the heat treatment chamber 30 .

[0114] The second fluid line 51 is connected to a second inert gas line 54 for supplying an inert gas to the second fluid line 51 , a water line 55 for supplying water vapor to the second fluid line 51 , and a reactive gas line 56 for supplying a reactive gas to the second fluid line 51 .

[0115] The second inert gas line 54 is provided with a second inert gas valve 64A for opening and closing the flow path and a second inert gas flow rate regulating valve 64B for regulating the flow rate of the inert gas supplied to the second fluid line 51 .

[0116] The water line 55 is provided with a water valve 65A for opening and closing the flow path and a water flow regulating valve 65B for regulating the flow rate of water vapor supplied to the second fluid line 51 .

[0117] The reactive gas line 56 is provided with a reactive gas valve 66A for opening and closing the flow path and a reactive gas flow rate regulating valve 66B for regulating the flow rate of the reactive gas supplied to the second fluid line 51 .

[0118] When the second inert gas valve 64A is opened, an inert gas is introduced into the sealed processing space SP through the plurality of second fluid introduction ports 10B, and the inert gas is supplied to the upper surface of the substrate W. When the water valve 65A is opened, water vapor is introduced into the sealed processing space SP through the plurality of second fluid introduction ports 10B, and the water vapor is supplied to the upper surface of the substrate W. When the reactive gas valve 66A is opened, a reactive gas is introduced into the sealed processing space SP through the plurality of second fluid introduction ports 10B, and the reactive gas is supplied to the upper surface of the substrate W.

[0119] When at least two of the second inert gas valve 64A, the water valve 65A, and the reactive gas valve 66A are opened, a mixed gas of inert gas, water vapor, and reactive gas corresponding to the valves opened is introduced (supplied) into the sealed processing space SP from the plurality of second fluid inlet ports 10B. When both the water valve 65A and the reactive gas valve 66A are opened, the water vapor and reactive gas mix in the second fluid line 51 to form an etching gas, which is then introduced into the sealed processing space SP from the plurality of second fluid inlet ports 10B.

[0120] By adjusting the openings of the second inert gas flow control valve 64B, the water flow control valve 65B, and the reactive gas flow control valve 66B, the concentration (partial pressure) of the reactive gas components and water vapor in the gas introduced from the plurality of second fluid inlet ports 10B into the closed processing space SP can be adjusted.

[0121] The second fluid line 51, the second inert gas line 54, and the second inert gas valve 64A are examples of an inert gas supply unit. The second fluid line 51, the water line 55, and the water valve 65A are examples of a water supply unit (steam supply unit). The second fluid line 51, the reactive gas line 56, and the reactive gas valve 66A are examples of a reactive gas supply unit. The water supply unit and the reactive gas supply unit function as an etching gas supply unit (etching fluid supply unit) that supplies etching gas into the heat treatment chamber 30.

[0122] The heat treatment unit 5 includes a plurality of fluid discharge ports 15 formed in the chamber body 31 for discharging the internal atmosphere of the heat treatment chamber 30. Each fluid discharge port 15 is a through-hole extending through the support portion 34 of the chamber body 31 on the side of the heating plate 20. The plurality of fluid discharge ports 15 are preferably arranged at intervals in the circumferential direction of the support portion 34.

[0123] The plurality of fluid discharge ports 15 include a plurality of first fluid discharge ports 15A connected to a first fluid discharge line 57 that primarily discharges oxidizing gas, and a plurality of second fluid discharge ports 15B connected to a second fluid discharge line 58 that primarily discharges etching gas. The first fluid discharge line 57 and the second fluid discharge line 58 are primarily composed of pipes.

[0124] A first fluid discharge valve 67 for opening and closing the flow path is installed in the first fluid discharge line 57, and a second fluid discharge valve 68 for opening and closing the flow path is installed in the second fluid discharge line 58. The first fluid discharge line 57 and the second fluid discharge line 58 can be configured to discharge fluid to a common exhaust device (not shown), or the exhaust destinations can be different.

[0125] Figure 3 It is a schematic diagram for explaining the state when the substrate W is carried into and out of the heat treatment unit 5 .

[0126] The substrate W is carried into the heat treatment unit 5 in the following manner. Figure 3 As shown in FIG. 2 , with the cover 32 in the upper position and the plurality of lift pins 40 in the upper position, the hand H of the transfer robot CR enters the heat treatment chamber 30 and delivers the substrate W to the plurality of lift pins 40. After the hand H is retracted from the heat treatment chamber 30, the pin lift drive mechanism 41 lowers the plurality of lift pins 40 supporting the substrate W from below, and places the substrate W on the heating surface 20 a of the heating plate 20 (see FIG. 2 ). Figure 2 With the substrate W placed on the heating surface 20a, the cover 32 is moved to a lower position to form a sealed processing space SP, thereby completing the loading of the substrate W.

[0127] On the other hand, the substrate W is carried out from the heat treatment unit 5 in the following manner. Figure 3 As shown, the lid lift drive mechanism 33 moves the lid 32 to the upper position, and the pin lift drive mechanism 41 moves the plurality of lift pins 40 to the upper position. With the lid 32 and the plurality of lift pins 40 in the upper position, the hand H of the transfer robot CR enters the heat treatment chamber 30 and receives the substrate W from the plurality of lift pins 40. The hand H of the transfer robot CR then retracts from the heat treatment chamber 30, completing the unloading of the substrate W.

[0128] Figure 4 1 is a block diagram showing the electrical configuration of a main portion of the substrate processing apparatus 1. The controller 3 includes a microcomputer and controls the control objects included in the substrate processing apparatus 1 according to a designated control program.

[0129] Specifically, the controller 3 may be a computer including a processor (CPU (Central Processing Unit)) 3a and a memory 3b storing a control program. The controller 3 is configured to execute various controls for substrate processing by the processor 3a executing the control program.

[0130] The specific control objects of the controller 3 are the conveying robots IR, CR, the pin lifting drive mechanism 41, the cover lifting drive mechanism 33, the heater 21, the first inert gas valve 62A, the first inert gas flow adjustment valve 62B, the oxidizing fluid valve 63A, the oxidizing fluid flow adjustment valve 63B, the second inert gas valve 64A, the second inert gas flow adjustment valve 64B, the water valve 65A, the water flow adjustment valve 65B, the reactive gas valve 66A, the reactive gas flow adjustment valve 66B, the first fluid discharge valve 67, the second fluid discharge valve 68, etc.

[0131] Hereinafter, an example of substrate processing will be described in which the metal layer exposed from the first main surface W1 of the substrate W is a gallium nitride layer, the oxidizing fluid is ozone gas, and the reactive gas is ammonia gas. Figure 5 This is a flowchart for explaining an example of substrate processing performed by the substrate processing apparatus 1 . Figure 5 It mainly shows the processing realized by the controller 3 executing the program.

[0132] In the substrate processing performed by the substrate processing apparatus 1, for example, Figure 5 As shown, first, a substrate loading step (step S1) and a pre-displacement step (step S2) are sequentially performed. Then, an oxidizing gas supply step (step S3), an oxidizing gas removal step (step S4), an etching gas supply step (step S5), a water supply continuation step (step S6), and a water removal step (step S7) are sequentially performed at least once each. After the final water removal step, a substrate unloading step (step S8) is performed.

[0133] Figure 6 This is a timing diagram of the process performed in the heat treatment chamber 30 during substrate processing. Figure 2 、 Figure 5 and Figure 6 .

[0134] First, the transfer robots IR and CR (see FIG1 ) carry an unprocessed substrate W from the carrier C into the processing unit 2 (substrate carrying step: step S1 ). The substrate W is placed on the heating surface 20 a of the hot plate 20 with the first principal surface W1 of the exposed gallium nitride layer facing upward (substrate placement step).

[0135] Then, the lid 32 is lowered, and the substrate W is placed on the heating plate 20 in the sealed processing space SP formed by the chamber body 31 and the lid 32. The substrate W placed on the heating surface 20a is heated to a predetermined oxidation temperature (first temperature) by the heating plate 20 (substrate heating step). The predetermined oxidation temperature is, for example, 100°C to 400°C.

[0136] With the sealed processing space SP formed, the first fluid discharge valve 67 and the first inert gas valve 62A are opened. Thus, inert gas is introduced into the sealed processing space SP through the first fluid inlet port 10A, while the atmosphere within the sealed processing space SP is exhausted to the exterior of the heat treatment chamber 30 through the first fluid discharge port 15A. In other words, before the oxidizing gas is supplied to the sealed processing space SP, the atmosphere within the sealed processing space SP is replaced with the inert gas (pre-replacement step: step S2).

[0137] By continuing the supply of inert gas for a specified replacement time, the atmosphere within the sealed processing space SP is fully replaced with the inert gas, thereby filling the sealed processing space SP with the inert gas. The specified replacement time is, for example, 10 seconds to 120 seconds. The flow rate of the inert gas during the pre-replacement step (pre-replacement flow rate) is a first flow rate. The first flow rate is, for example, 5 L / min to 50 L / min. The pre-replacement flow rate is the total flow rate of the inert gas introduced into the sealed processing space SP from the multiple first fluid inlet ports 10A.

[0138] With the sealed processing space SP filled with inert gas, the oxidizing fluid valve 63A is opened. Ozone gas is thereby introduced into the sealed processing space SP from the plurality of first fluid inlet ports 10A, and supplied to the first main surface W1 of the substrate W (oxidizing gas supply step: step S3). The oxidizing gas supply step is an example of an oxidizing fluid supply step.

[0139] The first main surface W1 of the substrate W is treated (oxidation treatment step) by ozone gas ejected from the plurality of first fluid inlet ports 10A. Specifically, a gallium oxide layer comprising one or more atomic layers is formed on the surface of the gallium nitride layer exposed from the first main surface W1 of the substrate W (metal oxide layer formation step, gallium oxide layer formation step). The substrate W is heated to an oxidation temperature on the hot plate 20. Therefore, in the metal oxide layer formation step, a heating and oxidation step is performed while the substrate W is heated to the oxidation temperature while ozone gas is supplied to the first main surface W1 of the substrate W.

[0140] The ozone gas is introduced into the sealed processing space SP for a predetermined oxidation processing time, which is, for example, 10 seconds to 300 seconds.

[0141] The flow rate of the oxidizing gas in the oxidizing gas supply step is a predetermined oxidizing flow rate. For example, the oxidizing flow rate is 5 L / min or more and 50 L / min or less. The oxidizing flow rate is the total flow rate of the oxidizing gas introduced into the sealed processing space SP from all first fluid inlet ports 10A.

[0142] During the process of introducing the oxidizing gas into the sealed processing space SP, the flow rate of the inert gas is adjusted to a first partial pressure-adjusted flow rate. The first partial pressure-adjusted flow rate is, for example, a second flow rate lower than the first flow rate. The second flow rate is, for example, not less than 0 L / min and not more than 50 L / min. The first partial pressure-adjusted flow rate is the total flow rate of the inert gas introduced into the sealed processing space SP from the plurality of first fluid inlet ports 10A.

[0143] By adjusting the flow rate of the inert gas, the partial pressure of the ozone gas in the sealed processing space SP can be adjusted to a partial pressure suitable for partially oxidizing one or several atomic layers of the surface layer of the gallium nitride layer (ozone gas partial pressure adjustment step, oxidizing gas partial pressure adjustment step).

[0144] Even when the ozone gas is supplied, the first fluid discharge valve 67 is maintained in an open state, so that the ozone gas in the sealed processing space SP is discharged from the first fluid discharge line 57 (first exhaust line).

[0145] After the first main surface W1 of the substrate W is treated with ozone gas, the oxidizing fluid valve 63A is closed. This allows the inert gas to continue to be ejected from the plurality of first fluid introduction ports 10A, while the ejection of ozone gas is stopped.

[0146] The atmosphere in the sealed processing space SP is replaced with the inert gas by supplying the inert gas to the main surface of the substrate W, thereby removing the ozone gas from the sealed processing space SP (oxidizing gas removing step: step S4 ). The oxidizing gas removing step is an example of an oxidizing fluid removing step.

[0147] While the oxidizing fluid valve 63A is closed, the first inert gas flow control valve 62B is controlled to change the inert gas flow rate to a specified oxidizing fluid removal flow rate. Alternatively, after the oxidizing fluid valve 63A is closed, the first inert gas flow control valve 62B is controlled to change the inert gas flow rate to a specified oxidizing fluid removal flow rate. The oxidizing fluid removal flow rate is, for example, the first flow rate. The oxidizing fluid removal flow rate is the total flow rate of the inert gas introduced into the closed processing space SP from all first fluid inlet ports 10A.

[0148] After the first main surface W1 of the substrate W is treated with ozone gas, the temperature of the heating plate 20 is lowered while the substrate W is maintained on the heating surface 20a. As the temperature of the heating plate 20 decreases, the temperature of the substrate W also decreases. Specifically, by changing the heater temperature to the etching temperature, the temperature of the heating plate 20 and the substrate W gradually decreases until it reaches the etching temperature (the second temperature). In this way, the heating of the substrate W is weakened, and the temperature of the substrate W is adjusted to a predetermined etching temperature lower than the oxidation temperature (temperature adjustment step, heat weakening step, low-temperature heating step). The etching temperature is, for example, 25°C or higher and less than 100°C.

[0149] The hot plate 20 functions as a temperature regulating member that regulates the temperature of the substrate W placed on a heating surface 20 a serving as a temperature regulating surface to a first temperature and a second temperature.

[0150] During the process of lowering the temperature of the substrate W, the first fluid exhaust valve 67 is closed and the second fluid exhaust valve 68 is opened. Thus, the exhaust destination (exhaust line) of the atmosphere from the closed processing space SP is changed from the first fluid exhaust line 57 (first exhaust line) to the second fluid exhaust line 58 (second exhaust line) (fluid exhaust line changing step).

[0151] When the temperature of the substrate W drops, the first inert gas valve 62A is closed and the second inert gas valve 64A is opened. This stops the discharge of inert gas from the plurality of first fluid inlet ports 10A and starts the discharge of inert gas from the plurality of second fluid inlet ports 10B. The second inert gas flow rate adjustment valve 64B is controlled to adjust the flow rate of the inert gas introduced from the plurality of second fluid inlet ports 10B into the sealed processing space SP to the first flow rate.

[0152] After the temperature of the substrate W reaches the etching temperature, the water valve 65A and the reactive gas valve 66A are opened. Thus, etching gas (a mixed gas of water vapor and ammonia) is introduced into the sealed processing space SP through the plurality of second fluid inlet ports 10B, thereby supplying etching gas to the first main surface W1 of the substrate W (etching gas supply process: step S5). The etching gas supply process is an example of an etching fluid supply process.

[0153] The etching gas ejected from the plurality of second fluid inlet ports 10B processes the first main surface W1 of the substrate W (etching process). Specifically, the gallium oxide layer formed on the first main surface W1 of the substrate W is etched, thereby selectively removing the gallium oxide layer (metal oxide layer removal process, gallium oxide layer removal process). In the metal oxide layer removal process, the gallium oxide layer is etched while the temperature of the substrate W is at the etching temperature (low-temperature etching process).

[0154] The etching gas is introduced into the sealed processing space SP for a predetermined etching processing time, which is, for example, 5 seconds to 120 seconds.

[0155] The water vapor flow rate during the etching gas supply process is a predetermined first etching flow rate. For example, the first etching flow rate is 5 L / min or more and 50 L / min or less. The water vapor flow rate during the etching gas supply process is the total flow rate of water vapor introduced into the sealed processing space SP from all second fluid inlet ports 10B.

[0156] The flow rate of ammonia gas during the etching gas supply process is a specified second etching flow rate. The second etching flow rate is, for example, 1 L / min or more and 50 L / min or less. The flow rate of ammonia gas during the etching gas supply process is the total flow rate of ammonia gas introduced into the sealed processing space SP from all second fluid inlet ports 10B.

[0157] While the etching gas is being introduced into the sealed processing space SP through the plurality of second fluid inlet ports 10B, the opening of the second inert gas flow control valve 64B is adjusted to adjust the inert gas flow rate to a second partial pressure-adjusted flow rate. The second partial pressure-adjusted flow rate is lower than the pre-replacement flow rate, for example, the second flow rate. The second partial pressure-adjusted flow rate is the total flow rate of the inert gas introduced into the sealed processing space SP through the plurality of second fluid inlet ports 10B.

[0158] By adjusting the flow rate of the inert gas, the partial pressure of water vapor and the partial pressure of ammonia gas in the sealed processing space SP can be adjusted to partial pressures suitable for selective etching of the gallium oxide layer (etching gas partial pressure adjustment step).

[0159] The temperature of the water vapor ejected from the second fluid introduction ports 10B is higher than the temperature (etching temperature) of the substrate W during the etching gas supply process. Therefore, the temperature of the water vapor decreases near the first main surface W1 of the substrate W, forming fine liquid water.

[0160] If the concentration of ammonia dissolved in the fine mist water is 1×10 -6If the concentration of ammonia is between 1 mol / L and 15 mol / L, selective etching of a gallium oxide layer having a thickness of one or several atomic layers can be achieved. The concentration of ammonia dissolved in the fine mist water is particularly preferably 1 mol / L.

[0161] After the gallium oxide layer is removed from the first main surface W1 of the substrate W, the water valve 65A is maintained open, while the reactive gas valve 66A is closed. This stops the introduction of ammonia gas into the sealed processing space SP through the plurality of second fluid introduction ports 10B, while water vapor continues to be introduced into the sealed processing space SP through the plurality of second fluid introduction ports 10B (water vapor supply continuing step: step S6). After the metal oxide layer removal step, the reactive gas is removed from the sealed processing space SP by continuing to introduce water vapor into the sealed processing space SP (reactive gas removal step, ammonia gas removal step).

[0162] After the supply of the reactive gas is stopped, water vapor is introduced into the sealed processing space SP for a predetermined water supply duration, which is, for example, 10 seconds to 120 seconds.

[0163] While water vapor is continuously supplied to the sealed processing space SP, the opening of the second inert gas flow control valve 64B is adjusted to maintain the inert gas flow rate at a predetermined ammonia removal flow rate. The ammonia removal flow rate is, for example, the same as the second partial pressure adjustment flow rate, which is the second flow rate. The inert gas flow rate during the water vapor supply continuous step is the total flow rate of the inert gas introduced into the sealed processing space SP from the plurality of second fluid inlet ports 10B.

[0164] After the water vapor continues to be supplied for the specified water supply duration, the water valve 65A is closed. This stops the supply of water vapor to the sealed processing space SP. Meanwhile, since the inert gas continues to be supplied to the sealed processing space SP, the water vapor is removed from the sealed processing space SP (water removal step, water vapor removal step: step S7).

[0165] While the water valve 65A is closed, the heating of the substrate W is increased to adjust the temperature of the substrate W to the oxidation temperature (heating enhancement step). Alternatively, after the water valve 65A is closed, the heating of the substrate W is increased to adjust the temperature of the substrate W to the oxidation temperature (heating enhancement step). Specifically, by changing the heater temperature to the specified etching temperature, the temperature of the heating plate 20 and the substrate W is gradually increased to reach the specified oxidation temperature.

[0166] During the process of increasing the temperature of the substrate W, the second fluid exhaust valve 68 is closed and the first fluid exhaust valve 67 is opened. Thus, the exhaust destination (exhaust line) of the atmosphere from the closed processing space SP is changed from the second fluid exhaust line 58 (second exhaust line) to the first fluid exhaust line 57 (first exhaust line) (fluid exhaust line changing step).

[0167] The inert gas flow rate is changed to a specified water removal flow rate simultaneously with closing the water valve 65A, or after closing the water valve 65A. The water removal flow rate is, for example, the first flow rate. The inert gas flow rate during the water removal process is the total flow rate of the inert gas introduced into the sealed processing space SP from all second fluid inlet ports 10B.

[0168] Then, the oxidizing gas supplying step (step S3 ) to the water removing step (step S7 ) may be performed again one or more times. Figure 5 "N" in the figure is an integer greater than or equal to 0 (N = 0, 1, 2, etc.). The cycle is repeated at least once. In the final water removal step (step S7), the heating and strengthening step is omitted, and instead, the substrate removal step (step S8) is performed. The substrate W removed from the thermal treatment unit 5 is transferred from the transfer robot CR to the transfer robot IR, and then stored in the carrier C by the transfer robot IR.

[0169] Figure 7 This is a schematic diagram for explaining changes in the surface state of the substrate W caused by repeating the metal oxide layer forming step and the metal oxide layer removing step in substrate processing.

[0170] use Figure 7 The changes in the surface condition of the gallium nitride layer 100 caused by the metal oxide layer forming step (step S3) and the metal oxide layer removing step (step S5) are described. Figure 7 (a) and Figure 7 As shown in (b), ozone gas (oxidizing gas) is supplied to the first main surface W1 of the substrate W, thereby forming a gallium oxide layer 101 containing one or several atomic layers on the surface of the gallium nitride layer 100 (metal oxide layer formation step). The thickness D1 of the gallium oxide layer 101 is not less than 0.3 nm and not more than 5 nm.

[0171] In the metal oxide layer formation step, a gallium oxide layer 101 comprising one or several atomic layers is formed. The thickness of one atomic layer of the gallium nitride layer 100 is substantially the same as the thickness of one atomic layer of the gallium oxide layer 101. The thickness of one atomic layer of the gallium oxide layer 101 is 1 nm or less (e.g., 0.3 nm to 0.4 nm). As described above, several atomic layers refers to two to ten atomic layers.

[0172] Then, if Figure 7 (c) and Figure 7 As shown in (d), an etching gas is supplied to the gallium oxide layer 101, thereby selectively removing the gallium oxide layer 101 from the substrate W (metal oxide layer removal step). Specifically, the gallium oxide layer 101, which is one or several atomic layers formed on the surface of the gallium nitride layer 100, is entirely removed. In this manner, by performing a single cycle consisting of a metal oxide layer forming step and a metal oxide layer removal step, the gallium nitride layer 100 is etched by an amount corresponding to a thickness D1 of one or several atomic layers.

[0173] Then, if Figure 7 (e) and Figure 7 As shown in (f), by further performing one cycle of treatment, the gallium nitride layer 100 is etched by an amount corresponding to a thickness D1 of one or several atomic layers. The thickness D1 of the gallium nitride layer 100 etched by one cycle of treatment remains substantially constant.

[0174] In the case of executing multiple loops, such as Figure 7 As shown in (g), on the surface of the GaN layer 100, the thickness D1 and the number of cycles ( Figure 7 A portion of thickness D2 corresponding to the product of the number of cycles (in (g)), D2 = D1 × number of cycles) is removed from the substrate W. The amount of the gallium nitride layer 100 etched by performing the multiple cycles corresponds to thickness D2.

[0175] Therefore, by adjusting the number of times the metal oxide layer forming step and the metal oxide layer removing step are repeatedly performed, a desired etching amount (the same amount as the thickness D2 ) can be achieved.

[0176] For example, if the gallium nitride layer 100 is etched by 0.3 nm in one cycle, by adjusting the number of cycles, it is possible to perform a substrate treatment that etches the gallium nitride layer 100 by 1.5 nm or 1.8 nm. In other words, the etching amount of the gallium nitride layer 100 can be controlled with sub-nanometer accuracy in each cycle.

[0177] Furthermore, in this substrate processing method, an etching gas containing water vapor and a reactive gas may be used to selectively remove the gallium oxide layer 101 .

[0178] Unlike this substrate processing method, if liquid water and a reactive liquid are supplied to the first main surface W1 of the substrate W in a continuous flow, unevenness will occur at the interface between the liquid water and the first main surface W1 of the substrate W. Consequently, at a molecular level, the frequency of collisions between the first main surface W1 of the substrate W and water molecules and reactive molecules will vary at various locations on the first main surface W1 of the substrate W.

[0179] Furthermore, in the heat treatment unit 5, since the substrate W does not rotate during heat treatment, when liquid water and reactive liquid are supplied to the first main surface W1 of the substrate W in a continuous flow manner, there is a concern that the first main surface W1 of the substrate W may not be sufficiently dried, resulting in watermarks.

[0180] Compared to liquid water, water vapor diffuses more easily near the first main surface W1 of the substrate W. Therefore, water molecules are more likely to collide evenly with various locations on the first main surface W1 of the substrate W. Consequently, compared to the case of removing the gallium oxide layer 101 using liquid, uneven etching amount on the first main surface W1 of the substrate W can be suppressed with sub-nanometer accuracy. This effect of suppressing uneven etching amount on the first main surface W1 of the substrate W is particularly significant when performing multiple cycles of processing.

[0181] When the material constituting the metal nitride layer is a nitride of a Group III metal other than gallium nitride, etching with sub-nanometer precision can be performed using water vapor and reactive gas as described above.

[0182] As described above, by performing at least one cycle of processing, the etching amount of the group III metal nitride layer can be well controlled at each position on the first main surface W1 of the substrate W with an accuracy of nanometers or less.

[0183] When hydrogen chloride gas is used as the reactive gas, a silicon carbide film must be provided on the inner wall of the heat treatment chamber 30 to protect the heat treatment chamber from corrosion caused by hydrogen chloride. On the other hand, when ammonia gas is used as the reactive gas, a protective film such as a silicon carbide film is not required on the inner wall of the heat treatment chamber 30. Consequently, the cost of the substrate processing apparatus 1 can be reduced.

[0184] According to the first embodiment, instead of completely replacing the etching gas with another gas, the reactive gas is removed from the sealed processing space SP by continuously supplying water vapor constituting the etching gas (a reactive gas removal step). This allows the reactive gas components adhering to the first main surface W1 of the substrate W to be adsorbed by the water and quickly removed.

[0185] According to the first embodiment, after the reactive gas removal step, water vapor present in the sealed processing space SP is replaced with an inert gas to remove the water vapor from the sealed processing space SP (water removal step). This can suppress unintended etching of the metal nitride layer caused by dissolved water molecules or a small amount of oxygen molecules in the water.

[0186] According to the first embodiment, after the metal oxide layer forming step and before the metal oxide layer removal step, an inert gas is supplied to the first main surface W1 of the substrate W, thereby replacing the oxidizing gas present in the sealed processing space SP with the inert gas. Thus, before the metal oxide layer removal step, the oxidizing gas is removed from the sealed processing space SP (oxidizing gas removal step). Consequently, unintended oxidation of the metal nitride layer during the metal oxide layer removal step can be suppressed.

[0187] According to the first embodiment, during the metal oxide layer removal step, the temperature of the substrate W is adjusted to a lower temperature than the etching gas supplied from the etching fluid supply unit to the first main surface W1 of the substrate W (temperature adjustment step). Consequently, the temperature of the etching gas decreases near the first main surface W1 of the substrate W, and the kinetic energy of the reactive molecules and water molecules near the first main surface W1 of the substrate W decreases. Consequently, the reactive molecules and water molecules adsorbed on the first main surface W1 of the substrate W are prevented from leaving the first main surface W1 of the substrate W. In other words, the adsorption of the reactive molecules and water molecules to the first main surface W1 of the substrate W is promoted. Consequently, the etching rate of the metal nitride layer can be increased. As a result, the etching amount per cycle of the cyclic treatment can be maintained at one or several atomic layers, and the etching rate of the metal nitride layer can be increased.

[0188] According to the first embodiment, in the metal oxide layer forming step, the metal oxide layer is formed by supplying an oxidizing gas to the first main surface W1 of the substrate W while heating the substrate W to an oxidation temperature (a first temperature) (a heated oxidation step). Then, in the metal oxide layer removing step, the metal oxide layer is etched by supplying an etching fluid to the first main surface W1 of the substrate W while the temperature of the substrate W is at an etching temperature (a second temperature) (a low-temperature etching step).

[0189] Specifically, when the temperature of the substrate W is a relatively high oxidation temperature (for example, above 100°C and below 400°C), the metal nitride layer on the first main surface W1 of the substrate W is oxidized, and when the temperature of the substrate W is a relatively low etching temperature (for example, above 25°C and below 100°C), etching is performed.

[0190] Therefore, during the metal oxide layer formation step, the oxidation rate of the metal nitride layer can be increased. Meanwhile, during the metal oxide layer removal step, if the temperature of the substrate W is relatively high, the small amount of oxygen contained in the etching fluid has oxidizing power, but etching is performed at a relatively low temperature. Therefore, during the metal oxide layer removal step, unintended oxidation of the metal nitride layer can be suppressed.

[0191] According to the first embodiment, both heating and cooling of the substrate W are performed while the substrate W is placed on the heating surface 20a of a single heating plate 20. Therefore, compared with a configuration in which the substrate W is moved to a member separate from the heating plate 20 in order to change its temperature, substrate processing can be simplified.

[0192] Furthermore, according to the first embodiment, a desired number of cycles of the metal oxide layer forming step and the metal oxide layer removing step are automatically executed by the controller 3. Therefore, a desired etching amount can be achieved by adjusting the number of times the metal oxide layer forming step and the metal oxide layer removing step are executed.

[0193] Figure 8 This is a schematic cross-sectional view of a modified example of the heat treatment unit 5 of the first embodiment. The modified example of the heat treatment unit 5 may include a cooling plate 70 that contacts the heating plate 20 and reduces the temperature of the heating plate 20. The cooling plate 70 is interposed between the support portion 34 of the chamber body 31 and the heating plate 20. A cooling medium path (not shown) is formed inside the cooling plate 70 through which a cooling medium (typically cooling water) circulates.

[0194] When substrate processing is performed using the heat treatment unit 5 of this modification, the temperature of the heating plate 20 can be quickly lowered by starting the circulation of cooling water without changing the heater output of the heating plate 20. That is, the temperature of the substrate W can be quickly lowered.

[0195] Figure 9 1 is a schematic cross-sectional view of a modified example of the processing unit 2 of the first embodiment. Figure 9 As shown, the processing unit 2 may further include a cooling unit 80 for cooling the substrate W heated by the heat treatment unit 5 within the dry chamber 4, and an indoor transfer mechanism 90 for transferring the substrate W within the dry chamber 4. The cooling unit 80 is disposed within the dry chamber 4 near the loading / unloading port 4a.

[0196] The cooling unit 80 includes a cooling plate 81, a plurality of lift pins 82 that penetrate the cooling plate 81 and move vertically, and a pin lift drive mechanism 83 that moves the lift pins 82 vertically. The cooling plate 81 has a cooling surface 81a on which the substrate W is placed. The plurality of lift pins 82 are connected by a connecting plate 84.

[0197] A cooling medium path (not shown) for circulating a cooling medium (typically cooling water) is formed within the cooling plate 81. A plurality of lift pins 82 move vertically between an upper position, in which they support the substrate W above the cooling surface 81a, and a lower position, in which their tips are submerged below the cooling surface 81a.

[0198] The indoor transfer mechanism 90 transfers substrates W within the dry chamber 4. More specifically, the indoor transfer mechanism 90 includes an indoor transfer hand 90H that transfers substrates W between the cooling unit 80 and the thermal treatment unit 5. The indoor transfer hand 90H is configured to receive and transfer substrates W to and from the plurality of lift pins 82 of the cooling unit 80, and to and from the lift pins 40 of the thermal treatment unit 5. Thus, the indoor transfer hand 90H can receive substrates W from the lift pins 82 of the cooling unit 80 and transfer them to the lift pins 40 of the thermal treatment unit 5. Furthermore, the indoor transfer hand 90H can receive substrates W from the lift pins 40 of the thermal treatment unit 5 and transfer them to the lift pins 82 of the cooling unit 80.

[0199] When the transfer robot CR (see FIG1 ) loads a substrate W into the dry chamber 4, the shutter 6 is controlled to an open position, opening the loading / unloading port 4a. In this state, the hand H of the transfer robot CR enters the dry chamber 4 and positions the substrate W above the cooling plate 81. This causes the plurality of lift pins 82 to rise to their upper positions, receiving the substrate W from the hand H of the transfer robot CR. The hand H of the transfer robot CR then retracts out of the dry chamber 4.

[0200] Next, the indoor transfer hand 90H of the indoor transfer mechanism 90 receives the substrate W from the plurality of lift pins 82 and transfers the substrate W to the thermal treatment unit 5. At this time, the lid 32 is in the open position (upper position), and the plurality of lift pins 40 support the received substrate W at the upper position. After the indoor transfer hand 90H retreats from the thermal treatment chamber 30, the lift pins 40 descend to the lower position, and the substrate W is placed on the heating surface 20a (refer to FIG. Figure 2 On the other hand, the cover 32 is lowered to the closed position (lower position), forming a closed processing space SP containing the heating plate 20. In this state, the substrate W is subjected to heat treatment (for example, Figure 4 Steps S2 to S8).

[0201] When the heat treatment is completed, the lid 32 is raised to the open position (upper position), opening the heat treatment chamber 30. Furthermore, the plurality of lift pins 40 are raised to the upper position, pushing the substrate W upward above the heating surface 20a. In this state, the indoor transfer hand 90H of the indoor transfer mechanism 90 receives the substrate W from the plurality of lift pins 40 and transfers it to the plurality of lift pins 82 of the cooling unit 80. The cooling unit 80 supports the received substrate W in the upper position. After the indoor transfer hand 90H retreats, the plurality of lift pins 82 descend to the lower position, placing the substrate W on the cooling surface 81a of the cooling plate 81. This allows the substrate W to be cooled.

[0202] When cooling of the substrate W is complete, the lift pins 82 rise to their upper positions, thereby pushing the substrate W upward onto the cooling surface 81a. In this state, the shutter 6 is opened, and the hand H of the transfer robot CR enters the dry chamber 4 and is positioned below the substrate W, which is supported by the lift pins 82 in the upper position. In this state, the lift pins 82 descend, transferring the substrate W to the hand H of the transfer robot CR. The hand H holding the substrate W retreats outside the dry chamber 4, and the shutter 6 closes the loading / unloading port 4a.

[0203] <Second embodiment>

[0204] Hereinafter, the configuration of a substrate processing apparatus 1P according to a second embodiment of the present invention will be described.

[0205] The main difference between the substrate processing apparatus 1P of the second embodiment and the substrate processing apparatus 1 of the first embodiment is that the heat treatment unit 5 of the substrate processing apparatus 1P includes a first heat treatment unit 5A (see Figure 10 ) and the second heat treatment unit 5B (reference Figure 11 ). Figure 10 It is a schematic cross-sectional view for explaining a configuration example of the first heat treatment unit 5A. Figure 11 : is a schematic cross-sectional view for explaining a configuration example of the second heat treatment unit 5B. Figure 10 and Figure 11 and the following Figure 12 In the above FIG1~ Figure 9 The same components as those in FIG. 1 and the like are denoted by the same reference numerals and their descriptions are omitted.

[0206] refer to Figure 10 The main difference between the first heat treatment unit 5A and the heat treatment unit 5 of the first embodiment is that the second fluid pipeline 51 is not provided in the first heat treatment unit 5A (refer to Figure 2 ), instead, all fluid inlet ports 10 in the first thermal treatment unit 5A are connected to the first fluid pipeline 50. In other words, all fluid inlet ports 10 provided in the first thermal treatment unit 5A are first fluid inlet ports 10A. Furthermore, all fluid outlet ports 15 provided in the first thermal treatment unit 5A are first fluid outlet ports 15A that primarily discharge oxidizing gas.

[0207] Hereinafter, the heat treatment chamber 30, the enclosed processing space SP, the heating plate 20 and the lifting pin 40 possessed by the first heat treatment unit 5A are also referred to as the first heat treatment chamber 30A (first chamber), the first enclosed processing space SP1, the first heating plate 20A and the first lifting pin 40A, respectively.

[0208] refer to Figure 11The main difference between the second thermal treatment unit 5B and the thermal treatment unit 5 of the first embodiment is that the second thermal treatment unit 5B does not have a first fluid line 50. Instead, all fluid inlet ports 10 of the second thermal treatment unit 5B are connected to a second fluid line 51. In other words, all fluid inlet ports 10 provided in the second thermal treatment unit 5B are second fluid inlet ports 10B. In addition, all fluid outlet ports 15 provided in the second thermal treatment unit 5B are second fluid outlet ports 15B that primarily discharge etching gas.

[0209] Hereinafter, the heat treatment chamber 30, the sealed processing space SP, the heating plate 20 and the lifting pins 40 possessed by the second heat treatment unit 5B are also referred to as the second heat treatment chamber 30B (second chamber), the second sealed processing space SP2, the second heating plate 20B and the second lifting pins 40B, respectively.

[0210] The substrate processing performed by the substrate processing apparatus 1P of the second embodiment is different from that of the substrate processing apparatus 1 of the first embodiment. Specifically, the metal oxide layer forming step and the metal oxide layer removing step are performed by different heat treatment units 5 . Figure 12 This is a flowchart for explaining an example of substrate processing performed by the substrate processing apparatus 1P.

[0211] In the substrate processing performed by the substrate processing apparatus 1P, for example, Figure 12 As shown, first, the first substrate moving-in process (step S11), the first pre-replacement process (step S12), the oxidizing gas supply process (step S13), the oxidizing gas removal process (step S14), the first substrate moving-out process (step S15), the second substrate moving-in process (step S16), the second pre-replacement process (step S17), the etching gas supply process (step S18), the water supply continuation process (step S19), the water removal process (step S20) and the second substrate moving-out process (step S21) are performed in sequence at least once each.

[0212] The following are the main references Figures 10 to 12 .

[0213] First, an unprocessed substrate W is loaded from a carrier C into the first thermal treatment unit 5A by transfer robots IR and CR (see FIG1 ) (a first substrate loading step: step S11 ). The substrate W is then placed on the heating surface 20 a of the first heating plate 20A with its first primary surface W1, where the gallium nitride is exposed, facing upward (a first substrate loading step).

[0214] Next, the lid 32 of the first thermal processing chamber 30A is lowered, resulting in the following state: within the first sealed processing space SP1 formed by the chamber body 31 and the lid 32, a substrate W is placed on the first heating plate 20A. The substrate W placed on the heating surface 20a is heated to a predetermined oxidation temperature by the first heating plate 20A (substrate heating step). The predetermined oxidation temperature is, for example, 100°C to 400°C. The first heating plate 20A is an example of a first temperature control member, and the heating surface 20a of the first heating plate 20A is an example of a first temperature control surface.

[0215] With the first sealed processing space SP1 formed, the first fluid discharge valve 67 and the first inert gas valve 62A are opened. Consequently, inert gas is introduced into the first sealed processing space SP1 through the plurality of first fluid inlet ports 10A, while the atmosphere within the first sealed processing space SP1 is exhausted to the exterior of the heat treatment chamber 30 through the plurality of first fluid discharge ports 15A. In other words, before the oxidizing gas is supplied to the first sealed processing space SP1, the atmosphere within the first sealed processing space SP1 is replaced with the inert gas (first pre-replacement step: step S12).

[0216] By continuing the supply of inert gas for a specified first replacement time, the atmosphere in the first sealed processing space SP1 is fully replaced with the inert gas, thereby filling the first sealed processing space SP1 with the inert gas. The specified first replacement time is, for example, 10 seconds to 120 seconds. The flow rate of the inert gas in the first pre-replacement step (first pre-replacement flow rate) is a specified first flow rate. The first flow rate is, for example, 5 L / min to 50 L / min. The flow rate of the inert gas in the first pre-replacement step refers to the total flow rate of the inert gas introduced into the first sealed processing space SP1 from the multiple first fluid inlet ports 10A.

[0217] With the first sealed processing space SP1 filled with inert gas, the oxidizing fluid valve 63A is opened. Consequently, ozone gas is introduced into the first sealed processing space SP1 from the plurality of first fluid introduction ports 10A, and is supplied to the first main surface W1 of the substrate W (oxidizing gas supplying step, ozone gas supplying step: step S13).

[0218] The first main surface W1 of the substrate W is treated (oxidation treatment step) using ozone gas ejected from the plurality of first fluid inlet ports 10A. Specifically, a gallium oxide layer comprising one or more atomic layers is formed on the surface of the gallium nitride layer exposed from the first main surface W1 of the substrate W (metal oxide layer formation step, gallium oxide layer formation step). The ozone gas is introduced into the first sealed processing space SP1 for a predetermined oxidation treatment time. The predetermined oxidation treatment time is, for example, 10 seconds to 120 seconds.

[0219] The flow rate of the oxidizing gas during the oxidizing gas supply step is a predetermined oxidizing flow rate. For example, the oxidizing flow rate is 5 L / min or higher and 50 L / min or lower. The flow rate of the oxidizing gas during the oxidizing gas supply step is the total flow rate of the oxidizing gas introduced into the first sealed processing space SP1 from all first fluid inlet ports 10A.

[0220] During the process of introducing the oxidizing gas into the first sealed processing space SP1, the first inert gas flow rate control valve 62B is controlled to adjust the inert gas flow rate to a first partial pressure-adjusted flow rate. The first partial pressure-adjusted flow rate is, for example, a second flow rate lower than the first flow rate. The second flow rate is, for example, not less than 5 L / min and not more than 50 L / min. The first partial pressure-adjusted flow rate is the total flow rate of the inert gas introduced into the first sealed processing space SP1 from the plurality of first fluid inlet ports 10A.

[0221] By adjusting the flow rate of the inert gas, the partial pressure of the ozone gas in the first sealed processing space SP1 can be adjusted to a partial pressure suitable for partially oxidizing one or several atomic layers of the surface layer of the gallium nitride layer (ozone gas partial pressure adjustment step, oxidizing gas partial pressure adjustment step).

[0222] During the supply of the ozone gas, the first fluid discharge valve 67 is maintained in an open state, and thus the ozone gas in the first sealed processing space SP1 is discharged from the first fluid discharge line 57 .

[0223] After the first main surface W1 of the substrate W is treated with ozone gas, the oxidizing fluid valve 63A is closed. Thus, the inert gas continues to be ejected from the plurality of first fluid introduction ports 10A, while the ejection of ozone gas is stopped.

[0224] By supplying the inert gas to the main surface of the substrate W, the atmosphere in the first sealed processing space SP1 is replaced with the inert gas, and the ozone gas is removed from the first sealed processing space SP1 (oxidizing gas removal step: step S14 ).

[0225] While the oxidizing fluid valve 63A is closed, the first inert gas flow control valve 62B is controlled to change the inert gas flow rate to a specified oxidizing fluid exclusion flow rate. Alternatively, after the oxidizing fluid valve 63A is closed, the first inert gas flow control valve 62B is controlled to change the inert gas flow rate to a specified oxidizing fluid exclusion flow rate. The oxidizing fluid exclusion flow rate is, for example, the first flow rate. The oxidizing fluid exclusion flow rate is the total flow rate of the inert gas introduced into the first closed processing space SP1 from the plurality of first fluid inlet ports 10A.

[0226] Then, the substrate W that has undergone the oxidation treatment is carried out of the first thermal treatment unit 5A (step S15: first substrate carrying-out step).

[0227] The substrate W unloaded from the first thermal treatment unit 5A is loaded into the second thermal treatment unit 5B by the transfer robot CR (step S16: second substrate loading step). The substrate W is placed on the heating surface 20a of the second heating plate 20B with the first main surface W1 facing upward (second substrate placement step).

[0228] Next, the lid 32 of the second thermal processing chamber 30B is lowered, resulting in the following state: within the second sealed processing space SP2 formed by the chamber body 31 and the lid 32, the substrate W is placed on the second heating plate 20B. The temperature of the substrate W placed on the heating surface 20a is adjusted to a predetermined etching temperature by the second heating plate 20B (temperature adjustment step). The predetermined etching temperature is, for example, 25°C or higher and lower than 100°C (low-temperature heating step). The second heating plate 20B is an example of a second temperature adjustment member having a lower temperature than the first temperature adjustment member, and the heating surface 20a of the second heating plate 20B is an example of a second temperature adjustment surface.

[0229] If the substrate W loaded into the second thermal processing chamber 30B has already cooled to a temperature lower than the etching temperature, the substrate W is placed on the heating surface 20a of the second heating plate 20B and heated to the etching temperature. Conversely, if the temperature of the substrate W loaded into the second thermal processing chamber 30B is higher than the etching temperature, the substrate W is placed on the heating surface 20a of the second heating plate 20B and cooled to the etching temperature.

[0230] After the second sealed processing space SP2 is formed, the second fluid discharge valve 68 and the second inert gas valve 64A are opened. Thus, inert gas is introduced into the second sealed processing space SP2 through the plurality of second fluid inlet ports 10B. Meanwhile, the atmosphere within the second sealed processing space SP2 is exhausted to the exterior of the second thermal processing chamber 30B through the plurality of second fluid discharge ports 15B. In other words, before the oxidizing gas is supplied to the second sealed processing space SP2, the atmosphere within the second sealed processing space SP2 is replaced with the inert gas (second pre-replacement step: step S17).

[0231] By continuing the supply of inert gas for a specified second replacement time, the atmosphere in the second closed processing space SP2 is fully replaced with the inert gas, thereby filling the second closed processing space SP2 with the inert gas. The specified second replacement time is, for example, 30 seconds. The flow rate of the inert gas in the second pre-replacement process (the second pre-replacement flow rate) is, for example, not less than 5 L / min and not more than 50 L / min. The second pre-replacement flow rate may also be the same as the first pre-replacement flow rate. The flow rate of the inert gas in the second pre-replacement process refers to the total flow rate of the inert gas introduced into the second closed processing space SP2 from all the second fluid inlet ports 10B.

[0232] After the temperature of the substrate W reaches the etching temperature, the water valve 65A and the reactive gas valve 66A are opened to supply etching gas (a mixed gas of water vapor and ammonia) from the plurality of second fluid introduction ports 10B to the second sealed processing space SP2 (etching gas supply process: step S18).

[0233] The etching gas ejected from the plurality of second fluid inlet ports 10B processes the first main surface W1 of the substrate W (etching process). Specifically, the gallium oxide layer formed on the first main surface W1 of the substrate W is etched, thereby selectively removing the gallium oxide layer (metal oxide layer removal process, gallium oxide layer removal process). In the metal oxide layer removal process, the gallium oxide layer is etched while the temperature of the substrate W is at the etching temperature (low-temperature etching process).

[0234] The etching gas is introduced into the second sealed processing space SP2 for a predetermined etching processing time, which is, for example, 10 seconds to 120 seconds.

[0235] The water vapor flow rate during the etching gas supply process is a specified water vapor flow rate. For example, the water vapor flow rate is 5 L / min or more and 50 L / min or less. The water vapor flow rate during the etching gas supply process is the total flow rate of water vapor introduced into the second sealed processing space SP2 from all second fluid inlet ports 10B.

[0236] The ammonia flow rate during the etching gas supply process is a specified ammonia flow rate. For example, the ammonia flow rate is 5 L / min or more and 50 L / min or less. The ammonia flow rate during the etching gas supply process is the total flow rate of ammonia gas introduced into the second sealed processing space SP2 from all second fluid inlet ports 10B.

[0237] While the etching gas is being introduced into the second sealed processing space SP2 from the plurality of second fluid inlet ports 10B, the second inert gas flow rate control valve 64B is controlled to adjust the inert gas flow rate to a second partial pressure-adjusted flow rate. The second partial pressure-adjusted flow rate is lower than the pre-replacement flow rate, for example, the second flow rate. The second partial pressure-adjusted flow rate is the total flow rate of the inert gas introduced into the second sealed processing space SP2 from the plurality of second fluid inlet ports 10B.

[0238] By reducing the flow rate of the inert gas, the partial pressure of water vapor and the partial pressure of ammonia gas in the second sealed processing space SP2 can be adjusted to partial pressures suitable for selective etching of the gallium oxide layer (etching gas partial pressure adjustment step).

[0239] The temperature of the water vapor ejected from the plurality of second fluid inlet ports 10B is higher than the temperature (etching temperature) of the substrate W during the etching gas supply process. Therefore, the temperature of the water vapor decreases near the first main surface W1 of the substrate W, forming a fine mist of water. If the concentration of ammonia dissolved in the fine mist of water is 1×10 -6 If the concentration of ammonia gas dissolved in the fine mist water is between 1 mol / L and 15 mol / L, selective etching of a gallium oxide layer having a thickness of one or several atomic layers can be achieved. The concentration of ammonia gas dissolved in the fine mist water is particularly preferably 1 mol / L.

[0240] After the gallium oxide layer is removed from the first main surface W1 of the substrate W, the water valve 65A remains open while the reactive gas valve 66A is closed. This stops the introduction of ammonia gas from the plurality of second fluid introduction ports 10B into the second sealed processing space SP2, while water vapor continues to be introduced from the plurality of second fluid introduction ports 10B into the second sealed processing space SP2 (water vapor supply continuing step: step S19). By continuing to introduce water vapor into the second sealed processing space SP2, the reactive gas is removed from the second sealed processing space SP2 (reactive gas removal step, ammonia gas removal step).

[0241] After the supply of the reactive gas is stopped, the water vapor is introduced into the second sealed processing space SP2 for a predetermined water supply duration, which is, for example, 10 seconds to 120 seconds.

[0242] While water vapor is continuously supplied to the second sealed processing space SP2, the inert gas flow rate is adjusted to a predetermined ammonia removal flow rate. The ammonia removal flow rate is, for example, the same as the second partial pressure adjustment flow rate, which is the second flow rate. The inert gas flow rate during the water vapor supply continuous step is the total flow rate of the inert gas introduced into the second sealed processing space SP2 from the plurality of second fluid inlet ports 10B.

[0243] After the water vapor continues to be supplied for the specified water supply duration, the water valve 65A is closed. This stops the supply of water vapor to the second sealed processing space SP2. Meanwhile, since the inert gas continues to be supplied to the second sealed processing space SP2, the water vapor is removed from the second sealed processing space SP2 (water removal step, water vapor removal step: step S20).

[0244] The inert gas flow rate is changed to a specified water removal flow rate simultaneously with closing the water valve 65A, or after closing the water valve 65A. The water removal flow rate is, for example, the first flow rate. The inert gas flow rate during the water removal process is the total flow rate of the inert gas introduced into the second sealed processing space SP2 from all second fluid inlet ports 10B.

[0245] Then, the first substrate carrying-in step (step S11 ) to the second substrate carrying-out step (step S21 ) may be performed again one or more times. Figure 12 Where "N" is an integer greater than or equal to 0 (N = 0, 1, 2, etc.). The cycle process is performed once or more, and the etched substrate W is unloaded from the second thermal treatment unit 5B (step S21: second substrate unloading step). Then, in the final second substrate unloading step, the substrate W is transferred from the transfer robot CR to the transfer robot IR and stored on the carrier C by the transfer robot IR.

[0246] The second embodiment achieves the same effects as the first embodiment. However, in the second embodiment, the temperature of the substrate W is adjusted on the heating surface 20a of the first heating plate 20A and then on the heating surface 20a of the second heating plate 20B. In other words, temperature adjustment (e.g., heating and cooling of the substrate W) is performed twice by different components (the first heating plate 20A and the second heating plate 20B). Therefore, compared to the configuration in the first embodiment where the temperature of the substrate W is adjusted by changing the temperature of the heating surface 20a of a single heating plate 20, the time required to adjust the temperature of the substrate W can be shortened.

[0247] In the second embodiment, a modified example of the first embodiment (see Figure 8 and Figure 9 In this case, in the first substrate unloading step (step S15) and the second substrate unloading step (step S21), the substrate W may be cooled to room temperature by the cooling plates 70 and 81 before being unloaded from the processing unit 2 by the transfer robot CR.

[0248] <Other embodiments>

[0249] The present invention is not limited to the above-described embodiments, and can be implemented in other forms.

[0250] For example, in the above embodiment, water vapor is used in the metal oxide layer removal step. However, in the metal oxide layer removal step, a mixed fluid of water vapor, mist water, and reactive gas, or a mixed fluid of mist water and reactive gas may be used as the etching fluid.

[0251] However, when water vapor is contained in the etching gas ejected from the second fluid inlet port 10B as in the aforementioned embodiments, compared to the case of using mist water, bulk water (in the form of microscopic droplets) is less likely to adhere to the first main surface W1 of the substrate W. Therefore, when water vapor is used as the water contained in the etching gas, water molecules can be made to collide more evenly with various locations on the first main surface W1 of the substrate W.

[0252] In the metal oxide forming step, it is not essential to use an oxidizing gas such as ozone gas; an oxidizing liquid such as a hydrogen peroxide solution may also be used. When the oxidizing liquid is a hydrogen peroxide solution, the concentration of hydrogen peroxide in the hydrogen peroxide solution is preferably 1 ppm to 100 ppm. Oxidizing gases and oxidizing liquids are collectively referred to as oxidizing fluids.

[0253] In the metal oxide forming step, the metal layer can be formed using O radicals generated by exciting oxygen in the air with UV (ultraviolet) irradiation. In the metal oxide forming step, the O radicals generated by UV irradiation can also be used in combination with an oxidizing fluid.

[0254] In the above embodiment, the substrate processing apparatus 1, 1P includes the transfer robots IR, CR, the processing unit 2, and the controller 3. However, the substrate processing apparatus of the present invention may be constituted by a single processing unit 2. In other words, the processing unit 2 may be an example of a substrate processing apparatus.

[0255] In each of the above embodiments, the inert gas and the oxidizing gas are introduced into the heat treatment chamber 30 (first heat treatment chamber 30A) from the first fluid inlet port 10A via a common first fluid line 50, and the inert gas, water vapor, and reactive gas are introduced into the heat treatment chamber 30 (second heat treatment chamber 30B) from the second fluid inlet port 10B via a common second fluid line 51. However, the fluids may be delivered to the fluid inlet port 10 from an inert gas line, an oxidizing gas line, a water line, a reactive gas line, or the like directly connected to the fluid inlet port 10, rather than through a common line such as the first fluid line 50 or the second fluid line 51. Furthermore, mixing valves for mixing the fluids may be provided in the first fluid line 50 and the second fluid line 51.

[0256] Alternatively, each fluid may be ejected from a nozzle provided in the heat treatment chamber 30 (the first heat treatment chamber 30A and the second heat treatment chamber 30B).

[0257] Alternatively, the etching gas (etching fluid) does not need to be mixed in the second fluid line 51 , but the pre-mixed etching gas (etching fluid) may be supplied from a supply source to the second fluid line 51 .

[0258] When the temperature of the substrate W (etching temperature) during the metal oxide layer removal step is room temperature (eg, 25° C.), the temperature of the substrate W can be lowered by stopping heating by the hot plate 20 in the substrate processing of the first embodiment.

[0259] When the temperature (etching temperature) of the substrate W in the metal oxide layer removal step is room temperature (for example, 25° C.), heating by the second heating plate 20B is not required in the substrate processing of the second embodiment.

[0260] While the embodiments of the present invention have been described in detail, these embodiments are merely specific examples for clarifying the technical content of the present invention. The present invention should not be construed as being limited to these specific examples, and the scope of the present invention is defined only by the appended claims.

Claims

1. A substrate processing method, comprising processing a substrate having a metal nitride layer containing a Group III metal on a main surface thereof, the method comprising: a metal oxide layer forming step of supplying an oxidizing fluid to the main surface of the substrate to form a metal oxide layer containing one atomic layer or several atomic layers on the surface of the metal nitride layer; and a metal oxide layer removal step of supplying an etching fluid containing at least one of gaseous water and misted water and a reactive gas that reacts with the metal oxide layer together with the water to the main surface of the substrate, thereby etching the metal oxide layer to selectively remove it from the substrate; and By performing a cyclic process in which the metal oxide layer forming step and the metal oxide layer removing step constitute one cycle at least once, the etching amount of the metal nitride layer is controlled with an accuracy of 5 nm or less in each cycle.

2. The substrate processing method according to claim 1 further includes a reactive gas removal process, in which, after the metal oxide layer removal process, at least one of gaseous water and mist water is continuously supplied to the main surface of the substrate to remove the reactive gas from the space connected to the main surface of the substrate.

3. The substrate processing method according to claim 2 further includes a water removal process, in which the water removal process is carried out after the reactive gas removal process, by replacing the water in the space in contact with the main surface of the substrate with an inert gas, thereby removing the water from the space in contact with the main surface of the substrate.

4. The substrate processing method according to any one of claims 1 to 3 further includes an oxidizing fluid removal process, wherein the oxidizing fluid removal process is performed after the metal oxide layer forming process and before the metal oxide layer removing process, by supplying an inert gas to the main surface of the substrate, thereby replacing the oxidizing fluid in the space connected to the main surface of the substrate with an inert gas, thereby removing the oxidizing fluid from the space connected to the main surface of the substrate.

5. A substrate processing method according to any one of claims 1 to 3, wherein the metal oxide layer removal process includes: an etching fluid supply process, supplying etching fluid from an etching fluid supply unit to the main surface of the substrate; and a temperature adjustment process, adjusting the temperature of the substrate to a temperature lower than that of the etching fluid supplied by the etching fluid supply unit.

6. The substrate processing method according to any one of claims 1 to 3, wherein the metal oxide layer forming step comprises a thermal oxidation step of forming the metal oxide layer by supplying the oxidizing fluid to the main surface of the substrate while heating the substrate; and The metal oxide layer removal step includes a low-temperature etching step of etching the metal oxide layer by supplying the etching fluid to the main surface of the substrate while the temperature of the substrate is lower than the temperature of the substrate in the metal oxide layer formation step. 7 . The substrate processing method according to claim 6 , wherein the temperature of the substrate in the thermal oxidation step is 100° C. or higher and 400° C. or lower, and the temperature of the substrate in the low-temperature etching step is 25° C. or higher and lower than 100° C.

8. The substrate processing method according to claim 6, wherein in the heating oxidation step, the substrate is heated by placing the substrate on a heating surface of a heating member disposed in a chamber while supplying the oxidizing fluid to the main surface of the substrate; and In the low-temperature etching step, the temperature of the substrate is lowered by lowering the temperature of the heating member while maintaining the substrate on the heating surface.

9. The substrate processing method according to claim 6, wherein in the heating oxidation step, the substrate is heated by placing the substrate on a first temperature control surface of a first temperature control member disposed in a first chamber while supplying the oxidizing fluid to the main surface of the substrate; and In the low-temperature etching step, the temperature of the substrate is lowered by moving the substrate from the first temperature control surface and placing the substrate on a second temperature control surface of a second temperature control member disposed in a second chamber and having a lower temperature than the first temperature control member. 10 . The substrate processing method according to claim 1 , wherein a thickness of the metal oxide layer formed in the metal oxide layer forming step is 5 nm or less. 11 . The substrate processing method according to claim 1 , wherein the metal nitride layer is a gallium nitride layer. 12 . The substrate processing method according to claim 1 , wherein the water contained in the etching fluid is gaseous water. 13 . The substrate processing method according to claim 1 , wherein the reactive gas is ammonia gas.

14. A substrate processing apparatus for processing a substrate having a metal layer on a main surface thereof, comprising: a temperature regulating member having a temperature regulating surface on which the substrate is mounted, and regulating the temperature of the substrate mounted on the temperature regulating surface to a predetermined first temperature and a second temperature lower than the first temperature; a chamber for accommodating the temperature regulating component; an oxidizing fluid supply unit for supplying an oxidizing fluid into the chamber to form an oxidized metal layer containing one or more atomic layers on the surface of the metal layer; and The etching fluid supply unit supplies an etching fluid containing at least one of gaseous water and misted water and a reactive gas that reacts with the metal oxide layer together with the water into the chamber to selectively etch the metal oxide layer.

15. The substrate processing apparatus according to claim 14, further comprising a controller configured to control the oxidizing fluid supply unit and the etching fluid supply unit; and The controller is programmed to execute: a metal oxide layer forming step of forming the metal oxide layer containing one atomic layer or several atomic layers on the surface layer of the metal layer by supplying the oxidizing fluid from the oxidizing fluid supply unit to the main surface of the substrate; and a metal oxide layer removing step of etching the metal oxide layer to selectively remove the metal oxide layer from the main surface of the substrate by supplying an etching fluid from the etching fluid supply unit to the main surface of the substrate; By performing a cyclic process in which the metal oxide layer forming step and the metal oxide layer removing step constitute one cycle at least once, the etching amount of the metal layer is controlled with an accuracy of 5 nm or less in each cycle.

16. The substrate processing apparatus according to claim 14 or 15, wherein the etching fluid supply unit is configured to supply the etching fluid into the chamber via a fluid inlet port opened in the chamber; and The second temperature is lower than a temperature of the etching fluid introduced into the chamber through the fluid introduction port.

17. The substrate processing apparatus according to claim 14 or 15, wherein the temperature adjustment member is configured to have a single temperature adjustment surface, and to adjust the temperature of the substrate to the first temperature and the second temperature in a state where the substrate is placed on the single temperature adjustment surface.

18. The substrate processing apparatus according to claim 14 or 15, wherein the temperature regulating member comprises: a first temperature regulating member having a first temperature regulating surface as the temperature regulating surface, and regulating the substrate placed on the first temperature regulating surface to the first temperature; and a second temperature regulating member having a second temperature regulating surface as the temperature regulating surface, and regulating the substrate placed on the second temperature regulating surface to the second temperature; and The chamber includes a first chamber for accommodating the first temperature regulating member and a second chamber for accommodating the second temperature regulating member; The oxidizing fluid supply unit is configured to supply the oxidizing fluid into the first chamber; The etching fluid supply unit is configured to supply the etching fluid into the second chamber. 19 . The substrate processing apparatus according to claim 14 , wherein the first temperature is 100° C. or higher and 400° C. or lower, and the second temperature is 25° C. or higher and lower than 100° C.

Images