Method for forming a gallium-containing film

Abstract

Embodiments of the present invention are methods for forming a gallium-containing film on a substrate on which a metal film, a silicon (Si) film, and at least one of a silicon oxide (SiO) film and a silicon nitride (SiN) film are formed, and the methods may include the steps of: preparing the substrate; injecting a gallium (Ga)-containing source gas onto the substrate; and injecting a nitrogen (N)-containing reactant gas onto the substrate to form a first gallium nitride (GaN) film on top of at least one of the silicon film and silicon nitride film of the substrate. Therefore, according to embodiments of the present invention, a gallium nitride film or a gallium oxide film can be easily formed. That is, a gallium nitride film or a gallium oxide film can be grown in one direction on a silicon (Si) substrate. As a result, a gallium nitride film or a gallium oxide film with suppressed defect formation can be formed. Consequently, there is an effect of improving the properties of the semiconductor device to which the gallium nitride film or gallium oxide film is applied.

Description

[Technical Field]

[0001] The present invention relates to a method for forming a gallium-containing film, and more particularly to a method for forming a gallium-containing film that can be easily formed. [Background technology]

[0002] Power semiconductor devices (also called power devices, power elements, or power semiconductor elements) are manufactured by depositing semiconductor compounds onto silicon (Si) wafers. Gallium nitride (GaN) has a wide bandgap and high electron mobility, making it a promising material for manufacturing high-speed, low-loss, and high-efficiency power semiconductor elements.

[0003] On the other hand, when forming gallium nitride (GaN) or gallium oxide (GaO) films, they can sometimes be formed directly on a silicon (Si) wafer, but there are cases where it is necessary to form a gallium nitride film on a silicon nitride (SiN) film, or a gallium oxide film on a silicon oxide (SiO) film.

[0004] By using the method according to the embodiment of the present invention, gallium-containing films such as gallium nitride films or gallium oxide films can be easily formed. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 2571583 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention provides a method for forming a gallium-containing film that can form a gallium-containing film in which the occurrence of defects is suppressed.

[0007] The present invention provides a method for forming a gallium-containing film that can grow in one direction. [Means for solving the problem]

[0008] A method for forming a gallium-containing film according to an embodiment of the present invention is a method for forming a gallium-containing film on a substrate on which a metal film, a silicon (Si) film, and at least one of a silicon oxide (SiO) film and a silicon nitride (SiN) film are formed, and may include the steps of: preparing the substrate; injecting a gallium (Ga)-containing source gas onto the substrate; and injecting a nitrogen (N)-containing reactant gas onto the substrate to form a first gallium nitride (GaN) film on top of at least one of the silicon film and the silicon nitride film of the substrate.

[0009] The step of injecting the reactant gas may include the step of forming a plasma using the reactant gas.

[0010] A method for forming a gallium-containing film according to an embodiment of the present invention may include a step, performed after the step of forming the first gallium nitride film, of injecting a gallium (Ga)-containing source gas and a nitrogen (N)-containing reactant gas to form a second gallium nitride film on the first gallium nitride film.

[0011] A method for forming a gallium-containing film according to an embodiment of the present invention includes the step of forming a third gallium nitride film on the second gallium nitride film, wherein the step of forming the third gallium nitride film may include the steps of injecting a gallium (Ga)-containing source gas onto the substrate and injecting a nitrogen (N)-containing reactant gas onto the substrate to form a third gallium nitride film on the second gallium nitride film.

[0012] A method for forming a gallium-containing film according to an embodiment of the present invention includes the step of forming a hydrogen plasma, and the step of forming the hydrogen plasma may be performed between the step of injecting the gallium (Ga)-containing source gas and the step of injecting the nitrogen (N)-containing reactant gas.

[0013] A method for forming a gallium-containing film according to an embodiment of the present invention includes the step of forming a hydrogen plasma, and the step of forming the hydrogen plasma may be performed after the step of injecting the nitrogen (N)-containing reactant gas has been completed.

[0014] The step of forming the second gallium nitride film may include the step of forming a plasma using the reactant gas.

[0015] A method for forming a gallium-containing film according to an embodiment of the present invention includes the step of forming a hydrogen plasma, which may be performed after the step of forming a second gallium nitride film by injecting the gallium (Ga)-containing source gas and nitrogen (N)-containing reactant gas.

[0016] A method for forming a gallium-containing film according to an embodiment of the present invention is a method for forming a gallium-containing film on a substrate on which a metal film, a silicon (Si) film, and at least one of a silicon oxide (SiO) film and a silicon nitride (SiN) film are formed, and may include the steps of: preparing the substrate; injecting a gallium (Ga)-containing source gas onto the substrate; and injecting an oxygen (O)-containing reactant gas onto the substrate to form a first gallium oxide (GaO) film on top of at least one of the silicon film and the silicon oxide film of the substrate.

[0017] The step of injecting the reactant gas may include the step of forming a plasma using the reactant gas.

[0018] The method for forming a gallium-containing film according to an embodiment of the present invention is performed after the step of forming the first gallium oxide film, and may include a step of forming a second gallium oxide film on the first gallium oxide film by injecting a gallium (Ga)-containing source gas and an oxygen (O)-containing reactant gas.

[0019] The method for forming a gallium-containing film according to an embodiment of the present invention includes a step of forming a third gallium oxide film on the second gallium oxide film. The step of forming the third gallium oxide film may include a step of injecting a gallium (Ga)-containing source gas onto the substrate and a step of injecting an oxygen (O)-containing reactant gas onto the substrate to form a third gallium oxide film on the second gallium oxide film.

[0020] The method for forming a gallium-containing film according to an embodiment of the present invention includes a step of forming hydrogen plasma, and the step of forming hydrogen plasma may be performed between the step of injecting the gallium (Ga)-containing source gas and the step of injecting the oxygen (O)-containing reactant gas.

[0021] The method for forming a gallium-containing film according to an embodiment of the present invention includes a step of forming hydrogen plasma, and the step of forming hydrogen plasma may be performed after the step of injecting the oxygen (O)-containing reactant gas is completed.

[0022] The step of forming the second gallium oxide film may include a step of forming plasma using the reactant gas.

[0023] The method for forming a gallium-containing film according to an embodiment of the present invention includes a step of forming hydrogen plasma, and the step of forming hydrogen plasma may be performed after the step of injecting the gallium (Ga)-containing source gas and the oxygen (O)-containing reactant gas to form the second gallium oxide film is completed.

Effects of the Invention

[0024] According to embodiments of the present invention, a gallium nitride film or a gallium oxide film can be easily formed. That is, a gallium nitride film or a gallium oxide film can be grown in one direction on a silicon (Si) substrate. Therefore, a gallium nitride film or a gallium oxide film with suppressed defect formation can be formed. Consequently, the properties of the semiconductor device to which the gallium nitride film or gallium oxide film is applied are improved. [Brief explanation of the drawing]

[0025] [Figure 1] This figure shows a state in which a gallium (Ga)-containing film has been formed on a substrate by the method according to the first embodiment of the present invention. [Figure 2] This figure shows a state in which a gallium (Ga)-containing film has been formed on a substrate by a method according to a modification of the first embodiment. [Figure 3] Figures (a) to (c) show a method for forming a gallium (Ga)-containing film on a substrate according to a second embodiment of the present invention. [Figure 4] This figure shows a state in which a gallium (Ga)-containing film has been formed on a substrate by a method according to a modification of the second embodiment. [Figure 5] This figure schematically shows a deposition apparatus for forming a gallium-containing film according to an embodiment of the present invention. [Modes for carrying out the invention]

[0026] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. However, the present invention is not limited in any way to the embodiments disclosed below and can be embodied in a variety of different forms, and these embodiments are provided merely to complete the disclosure of the present invention and to fully inform those in the ordinary skill of the scope of the invention. The drawings may be exaggerated in order to illustrate embodiments of the present invention, and in the drawings, the same reference numerals refer to the same components.

[0027] The present invention relates to a method for forming a gallium (Ga)-containing film. More specifically, it relates to a method for forming a gallium nitride (GaN) film or an oxidative nitride (GaO) film on a substrate.

[0028] Figure 1 shows a state in which a gallium (Ga)-containing film has been formed on a substrate by the method according to the first embodiment of the present invention.

[0029] The substrate 10 may be a substrate on which a metal film, a silicon (Si) film, and at least one of a silicon oxide (SiO) film and a silicon nitride (SiN) film are formed.

[0030] A substrate on which a metal film, a silicon (Si) film, a silicon oxide (SiO) film, and a silicon nitride (SiN) film are formed may include a base and a metal film formed on the base, a silicon (Si) film, and at least one of the silicon oxide (SiO) film and the silicon nitride (SiN) film.

[0031] The base may be any one of the following: a wafer, glass, metal plate, or polymer film. The wafer may be a silicon wafer (Si wafer), and many other types of wafers can also be used.

[0032] The metal film may also contain metals other than silicon (Si). For example, the metal film may contain at least one of tungsten, iridium, osmium, rhodium, platinum, silver, rhenium, and palladium.

[0033] Furthermore, the substrate on which the silicon (Si) film is formed may be a silicon wafer. In other words, the silicon film itself may represent the silicon wafer.

[0034] As described above, at least one of a metal film, a silicon (Si) film, a silicon oxide (SiO) film, and a silicon nitride (SiN) film may be formed on the base. In this case, at least two or more of the metal film, silicon (Si) film, silicon oxide (SiO) film, and silicon nitride (SiN) film may be formed on the base. That is, two or more, three or more, or four films of the metal film, silicon (Si) film, silicon oxide (SiO) film, and silicon nitride (SiN) film may be formed on the base.

[0035] Furthermore, when at least two of the following are formed on the base: a metal film, a silicon (Si) film, a silicon oxide (SiO) film, and a silicon nitride (SiN) film, two or more different films may be formed in different regions. For example, when a metal film, a silicon (Si) film, a silicon oxide (SiO) film, and a silicon nitride (SiN) film are formed on one side of a silicon wafer (base), the metal film, the silicon (Si) film, the silicon oxide (SiO) film, and the silicon nitride (SiN) may be formed in different regions on that side.

[0036] In the embodiment, a gallium (Ga)-containing film is formed on the substrate 10 as described above. The substrate 10 according to the first embodiment may be a substrate on which a silicon film is formed. That is, the substrate may be, for example, a silicon wafer. The gallium-containing film according to the first embodiment may be a gallium nitride (GaN) film 11.

[0037] The following describes a method for forming a gallium nitride film 11 on a substrate 10. Specifically, the method described is for forming the gallium nitride film 11 using atomic layer deposition (ALD).

[0038] The step of forming the gallium nitride film 11 may include a step of inserting the substrate 10 and injecting a source gas containing gallium (Ga) into the chamber (gallium (Ga)-containing source gas injection step) and a step of injecting a reactant gas containing nitrogen (N) (nitrogen (N)-containing reactant gas injection step). The step of forming the gallium nitride film 11 is performed in a cycle of "gallium (Ga)-containing source gas injection step - nitrogen (N)-containing reactant gas injection step" (hereinafter referred to as the gallium nitride film formation cycle (CY)). GaN )) may also be used. That is, the step of forming the gallium nitride film 11 may be the gallium nitride film formation cycle (CY GaN ) including the formation cycle (CY) of the gallium nitride film GaN The procedure may include a step of injecting a gallium (Ga)-containing source gas and a step of injecting a nitrogen (N)-containing reactant gas. Here, in the step of injecting the nitrogen (N)-containing reactant gas, a plasma (first plasma) may be generated (PEALD). That is, a nitrogen plasma is generated using a nitrogen (N)-containing reactant gas.

[0039] Furthermore, the step of forming the gallium nitride film 11 may further include at least one of the following steps: a step of injecting a purge gas between the gallium (Ga)-containing source gas injection step and the nitrogen (N)-containing reactant gas injection step (primary purge step), and a step of injecting a purge gas after the nitrogen (N)-containing reactant gas injection step (secondary purge step). In such a case, the sequence "gallium (Ga)-containing source gas injection step - primary purge step - nitrogen (N)-containing reactant gas injection - secondary purge step" constitutes one cycle (gallium nitride film formation cycle (CY)). GaN )) may also be used. That is, the step of forming the gallium nitride film 11 may be the gallium nitride film formation cycle (CY GaN ) including the formation cycle (CY) of the gallium nitride film GaNThe gallium nitride film formation cycle (CY) may include a step of injecting a gallium (Ga)-containing source gas, a primary purge step, an injection step of a nitrogen (N)-containing reactant gas, and a secondary purge step. GaN In this process, at least one of the primary purge step and the secondary purge step can be omitted.

[0040] The following describes the formation cycle (CY) of gallium nitride films. GaN Let's explain this in more detail.

[0041] In the step of injecting a gallium (Ga)-containing source gas, a source gas containing (or having) gallium (Ga) is injected toward the substrate 10. That is, a source gas containing gallium (Ga) is injected into the chamber in which the substrate 10 is placed. Here, as the gallium (Ga)-containing source gas, for example, trimethylgallium (Ga(CH3)3) (TMGa) can be used. Needless to say, the gallium (Ga)-containing source gas is not limited in any way to the material described above, and a wide variety of gases containing gallium (Ga) can be used.

[0042] When a source gas containing gallium (Ga) is sprayed toward the substrate 10, the source gas is deposited or adsorbed onto one side of the substrate 10, resulting in the deposition of a gallium (Ga)-containing layer. In other words, a gallium metal film is deposited on top of a silicon (Si) film.

[0043] Once the step of injecting the gallium (Ga)-containing source gas is complete, a purge gas is injected into the chamber containing the substrate 10 to perform a primary purge. For example, argon (Ar) gas can be used as the purge gas.

[0044] Once the primary purging is complete, a nitrogen (N)-containing reactant gas is injected into the chamber. For example, a gas containing NH3 can be used as the nitrogen (N)-containing reactant gas. Needless to say, the nitrogen (N)-containing reactant gas is not limited to the material mentioned above; a wide variety of nitrogen (N)-containing gases can be used. When the nitrogen (N)-containing reactant gas is injected into the chamber, it reacts with the gallium metal film formed on the substrate 10. This forms a gallium nitride film 11.

[0045] In this embodiment, when nitrogen (N)-containing reactant gas is injected into the chamber, a plasma (first plasma) is generated inside the chamber. That is, nitrogen plasma is generated by discharging the nitrogen (N)-containing reactant gas. When injecting the nitrogen (N)-containing reactant gas, a discharge gas may also be injected together, and argon (Ar) gas can be used as the discharge gas.

[0046] The following is a brief explanation of how to generate plasma (the first plasma). A high-frequency (RF: Radio Frequency) power supply is supplied to at least one of the susceptor on which the substrate 10 is placed inside the chamber, or to the injection unit that injects gas into the chamber. In addition, nitrogen (N)-containing reactant gas and argon (Ar) gas are injected into the chamber via the injection unit. As described above, by supplying RF power and injecting nitrogen (N)-containing reactant gas and argon (Ar) gas, a nitrogen (N)-containing plasma, i.e., nitrogen plasma, can be generated inside the chamber.

[0047] In this way, by generating a nitrogen plasma when injecting nitrogen (N)-containing reactant gas, the gallium nitride film 11 can be easily grown. That is, the gallium nitride film 11 can be grown in one direction. As a result, a gallium nitride film 11 with suppressed defect formation can be formed.

[0048] Thereafter, a purge gas is injected into the chamber in which the substrate 10 is loaded to perform a secondary purge. At this time, as the purge gas, the same gas as that used in the primary purge can be used. For example, argon (Ar) gas can be used.

[0049] A process including the injection step of the gallium (Ga)-containing source gas, the primary purge step, the injection step of the nitrogen (N)-containing reactant gas, and the secondary purge step as described above may be defined as one cycle (CY GaN ) for forming a gallium nitride film. That is, the cycle (CY GaN ) for forming the gallium nitride film 11 may include the steps of "injecting the gallium (Ga)-containing source gas - primary purge step - injecting the nitrogen (N)-containing reactant gas - secondary purge step". In the step of injecting the nitrogen (N)-containing reactant gas, plasma (first plasma) is generated. Then, the cycle (CY GaN ) for forming the gallium nitride film may be performed continuously one or more times.

[0050] When forming the gallium nitride film 11 by atomic layer deposition, hydrogen plasma (H2 Plasma) may be generated (as the second plasma). That is, the cycle (CY GaN ) for forming the gallium nitride film may include a step of generating hydrogen plasma after the step of injecting the nitrogen (N)-containing reactant gas and exposing the gallium nitride film 11 to the hydrogen plasma. For this reason, the cycle (CY GaN ) for forming the gallium nitride film may include the steps of "injecting the gallium (Ga)-containing source gas - primary purge step - injecting the nitrogen (N)-containing reactant gas - exposure step to hydrogen plasma - secondary purge step".

[0051] The following is a brief explanation of how to generate hydrogen plasma (second plasma). A high-frequency (RF) power supply is supplied to at least one of the susceptor on which the substrate 10 is placed inside the chamber, or to the injection unit that injects gas into the chamber. A gas containing hydrogen (H2) is used as the plasma generation gas. More specifically, the plasma generation gas may be hydrogen (H2) gas. Alternatively, a gas containing argon (Ar) may be injected along with the hydrogen gas. As described above, by supplying RF power and injecting the gas containing hydrogen (H2) and the gas containing argon (Ar), a plasma containing hydrogen (H2), i.e., hydrogen plasma (second plasma), can be generated inside the chamber. As a result, the gallium nitride film 11 is exposed to the hydrogen plasma.

[0052] The step of exposure to hydrogen plasma (second plasma), as described above, is the step of generating hydrogen plasma and exposing the gallium nitride film 11 to the hydrogen plasma. For this reason, the step of exposure to hydrogen plasma may also be called the hydrogen plasma generation step.

[0053] The gallium (Ga)-containing source gas or nitrogen (N)-containing reactant gas may contain impurities. Furthermore, residual impurities inside the chamber may flow into the gallium nitride film 11 formed on the substrate 10. These impurities may degrade the properties of the gallium nitride film 11 or the properties of an element equipped with the gallium nitride film, such as a power semiconductor element (power device). Therefore, it is preferable to remove the impurities contained in the gallium nitride film 11.

[0054] Therefore, in this embodiment, after depositing a gallium nitride film 11 by injecting a nitrogen (N)-containing source gas, the gallium nitride film 11 is exposed to a hydrogen plasma to remove impurities. When the gallium nitride film 11 is exposed to a hydrogen plasma, the impurities contained in the gallium nitride film 11 react with hydrogen. As a result, the impurities contained in the gallium nitride film 11 react with hydrogen and become a gas, escaping from the gallium nitride film 11. Consequently, the amount of impurities contained in the gallium nitride film 11 is reduced.

[0055] The above describes the process of exposing the gallium nitride film 11 to a hydrogen plasma after injecting a nitrogen (N)-containing reactant gas. However, the present invention is not limited thereto, and a hydrogen plasma may be generated between the step of injecting a gallium (Ga)-containing source gas and the step of injecting a nitrogen (N)-containing reactant gas, thereby exposing the gallium metal film to the hydrogen plasma to remove impurities. In such a case, the formation cycle (CY) of the gallium nitride film is GaN The procedure may include the steps of "injecting a gallium (Ga)-containing source gas - exposure to a hydrogen plasma - primary purging step - injection of a nitrogen (N)-containing reactant gas - secondary purging step".

[0056] Furthermore, the hydrogen plasma exposure step may be performed twice. That is, hydrogen plasma may be generated between the step of injecting gallium (Ga)-containing source gas and the step of injecting nitrogen (N)-containing reactant gas (primary hydrogen plasma exposure step), and hydrogen plasma may be generated after injecting nitrogen (N)-containing reactant gas (secondary plasma exposure step). In such a case, the gallium nitride film formation cycle (CY) GaN The procedure may include the steps of "injecting a gallium (Ga)-containing source gas - exposure to a primary hydrogen plasma - primary purging step - injection of a nitrogen (N)-containing reactant gas - exposure to a primary hydrogen plasma - secondary purging step".

[0057] Figure 2 shows a state in which a gallium (Ga)-containing film has been formed on a substrate by a modified method according to the first embodiment.

[0058] In the first embodiment described above, the formation of the gallium nitride film 11 by atomic layer deposition (ALD) was explained. However, the present invention is not limited thereto, and the gallium nitride film 11 may be formed using both atomic layer deposition (ALD) and chemical vapor deposition (CVD).

[0059] Hereinafter, a method for forming a gallium nitride film 11 on a substrate 10 by a modified method of the first embodiment will be described based on Figure 2. For ease of explanation, the gallium nitride film formed by atomic layer deposition (ALD) will be referred to as the first gallium nitride film 11a, and the gallium nitride film formed by chemical vapor deposition (CVD) will be referred to as the second gallium nitride film 11b. Furthermore, the formation of the first gallium nitride film 11a by atomic layer deposition (ALD) will be simply referred to as the "first deposition method," and the formation of the second gallium nitride film 11b by chemical vapor deposition (CVD) will be simply referred to as the "second deposition method."

[0060] Referring to Figure 2, the method for forming the gallium nitride film 21 includes the steps of forming a first gallium nitride film 11a by atomic layer deposition (ALD) and forming a second gallium nitride film 11b by chemical vapor deposition (CVD). That is, the steps for forming the gallium nitride film 21 include the steps of forming a first gallium nitride film 11a by the first deposition method and forming a second gallium nitride film 11b by the second deposition method. In this case, the second deposition method may be performed after the first deposition method (ALD-CVD). As a result, a gallium nitride film 11 can be formed on the substrate 10 in which the first gallium nitride film 11a and the second gallium nitride film 11b are laminated.

[0061] The following briefly describes a method for forming a second gallium nitride film 11b on a first gallium nitride film 11a using chemical vapor deposition (CVD).

[0062] The step of forming the second gallium nitride film 11b by chemical vapor deposition (CVD) may include the step of injecting a gallium (Ga)-containing source gas and a nitrogen (N)-containing reactant gas into the chamber in which the first gallium nitride film 11a is formed. At this time, the gallium (Ga)-containing source gas and the nitrogen (N)-containing reactant gas are injected together or simultaneously. When the gallium (Ga)-containing source gas and the nitrogen (N)-containing reactant gas are injected into the chamber, the gallium (Ga) and nitrogen (N) react. As a result, the second gallium nitride film 11b is formed on top of the first gallium nitride film 11a.

[0063] When forming the second gallium nitride film 11b by the chemical vapor deposition method described above, a plasma (first plasma) may be generated. That is, a plasma may be generated in the step of injecting a gallium (Ga)-containing source gas and a nitrogen (N)-containing reactant gas together (PECVD). When injecting the gallium (Ga)-containing source gas and the nitrogen (N)-containing reactant gas, a discharge gas may also be injected together, and argon (Ar) gas can be used as the discharge gas. The plasma generated at this time may be a plasma containing gallium (Ga) and nitrogen (N), or it may be a nitrogen plasma containing an even larger amount of nitrogen (N) than gallium (Ga).

[0064] The following is a brief explanation of how to generate plasma (the first plasma). A high-frequency (RF) power supply is supplied to at least one of the susceptor on which the substrate 10 is placed inside the chamber, or to the injection unit that injects gas into the chamber. In addition, gallium (Ga)-containing source gas, nitrogen (N)-containing reactant gas, and argon (Ar) gas are injected into the chamber through the injection unit. As described above, by supplying RF power and injecting gas, plasma, specifically nitrogen plasma, can be generated inside the chamber.

[0065] In this way, by generating a plasma (first plasma) when injecting a gallium (Ga)-containing source gas and a nitrogen (N)-containing reactant gas, the second gallium nitride film 11b can be easily grown. That is, the second gallium nitride film 11b can be grown in one direction. As a result, a second gallium nitride film 11b with suppressed defect formation can be formed.

[0066] When forming the second gallium nitride film 11b by chemical vapor deposition, a hydrogen plasma (H2 Plasma) (second plasma) may be generated. That is, after forming the second gallium nitride film 11b by injecting a gallium (Ga)-containing source gas and a nitrogen (N)-containing gas, a hydrogen plasma may be generated and the second gallium nitride film 11b may be exposed to the hydrogen plasma. This makes it possible to remove impurities contained in the second gallium nitride film 11b. Needless to say, the hydrogen plasma may be generated while injecting the gallium (Ga)-containing source gas and the nitrogen (N)-containing gas.

[0067] Another example is that a gallium nitride film may be formed by performing at least one of the first and second deposition methods multiple times with a time difference between them. For example, a method for forming a gallium nitride film 11 may include the steps of forming a first gallium nitride film 11a by the first deposition method, forming a second gallium nitride film 11b by the second deposition method, and forming a first gallium nitride film 11a by the first deposition method (ALD-CVD-ALD).

[0068] Needless to say, the present invention is not limited thereto, and the steps of forming a first gallium nitride film 11a by a first evaporation method and forming a second gallium nitride film 11b by a second evaporation method may be performed alternately multiple times. That is, the method for forming the gallium nitride film 11 may include the steps of forming a first gallium nitride film 11a by a first evaporation method, forming a second gallium nitride film 11b by a second evaporation method, and forming a first gallium nitride film 11a by a first evaporation method and forming a second gallium nitride film 11b by a second evaporation method (ALD-CVD-ALD-CVD).

[0069] The above describes the formation of a gallium nitride film 11 on a substrate 10 on which a silicon film is formed. In other words, the description describes the formation of a gallium nitride film 11 on a silicon wafer. However, the substrate 10 does not have to be a silicon wafer; it may be a substrate on which a silicon film, a silicon nitride film, a silicon oxide film, and at least one of these metal films are formed on one side.

[0070] For example, the substrate 10 may comprise a base and a silicon film formed on the base, a silicon nitride film, a silicon oxide film, and at least one of a metal film. In this case, the base may not be a silicon wafer, but one of glass, a metal plate, or a polymer film. That is, the substrate 10 may have at least two different films formed on one side of the base, consisting of a silicon film, a silicon nitride film, a silicon oxide film, and a metal film. In this case, the two or more different films may be formed in different regions on one side of the base. To give a more specific example, the substrate 10 may have a silicon film and a silicon nitride film formed on the base. In such a case, a gallium nitride film 11 may be formed on top of at least one of the silicon film and the silicon nitride film. To give another example, the substrate 10 may have at least one of a silicon film and a silicon nitride film, and at least one of a silicon oxide film and a metal film formed on the base. In such a case, a gallium nitride film may be formed on top of at least one of the silicon film and the silicon nitride film.

[0071] In the first embodiment described above, the formation of a gallium nitride film 11 on a substrate, i.e., a silicon wafer, was described. However, the present invention is not limited thereto, and a gallium oxide (GaO) film may be formed on a substrate 10. In this case, the method for forming the gallium oxide (GaO) film is the same as in the first embodiment and its modifications described above. The only difference is that an oxygen-containing reactant gas is used as the reactant gas.

[0072] In this case, the substrate 10 may have a silicon film and a silicon oxide film formed on a base. In such a case, a gallium oxide film may be formed on top of at least one of the silicon film and the silicon oxide film. To give another example, the substrate 10 may have at least one of the silicon film and the silicon oxide film and at least one of the silicon nitride film and the metal film formed on a base. In such a case, a gallium oxide film may be formed on top of at least one of the silicon film and the silicon oxide film.

[0073] The gallium nitride or gallium oxide film formed by the method according to the first embodiment and its modification may be a component of a power semiconductor device or a field-effect transistor. More specifically, the gallium nitride or gallium oxide film formed by the method according to the first embodiment may be an active layer or channel layer that is a component of a power semiconductor device.

[0074] Furthermore, the gallium oxide film formed by the method according to this embodiment is applicable to the manufacture of overcurrent prevention elements in power plants that require ultra-high voltage or high-capacity power. That is, a portion of the components of an overcurrent prevention element in a power plant that requires ultra-high voltage or high-capacity power may include the gallium oxide film formed by the method according to this embodiment.

[0075] As described above, a gallium nitride film or a gallium oxide film can be easily formed on a silicon (Si) substrate 10 by the method according to the first embodiment and its modifications. This has the effect of improving the characteristics of devices to which the gallium nitride film or gallium oxide film is applied, such as power semiconductor devices.

[0076] Figures 3(a) to 3(c) show a method for forming a gallium (Ga)-containing film on a substrate according to a second embodiment of the present invention.

[0077] In the first embodiment and its modifications described above, a gallium nitride film was formed on at least one of the substrates on which a silicon film is formed and the substrate on which a silicon nitride film is formed, or a gallium oxide film was formed on at least one of the substrates on which a silicon film is formed and the substrate on which a silicon oxide film is formed. However, as shown in Figure 3(a), other films that do not contain silicon (Si) may be formed on at least a portion of the substrate 10, and there may be cases where a gallium nitride film or a gallium oxide film must be formed on top of the other films that do not contain silicon (Si).

[0078] For example, the substrate may be a silicon wafer, and a film other than silicon (Si) may be formed on a portion of one side of the substrate. In such a case, a portion of one side of the substrate 10 may be exposed, and a portion may not be exposed. Needless to say, the entire one side of the substrate 10 may not be exposed.

[0079] Furthermore, when manufacturing power semiconductor devices, there are cases where it is necessary to form a gallium nitride film or a gallium oxide film on a film that does not contain silicon. In such cases, it is preferable to first form a silicon nitride (SiN) film or a silicon oxide (SiO) film on a film that does not contain silicon, and then form a gallium nitride film or a gallium oxide film on the silicon nitride film or silicon oxide film.

[0080] In the following, for the sake of clarity, the film formed on the substrate 10 and which does not contain silicon (Si) will be referred to as "the lower film 1".

[0081] In this embodiment, in order to form a gallium (Ga)-containing film on a silicon (Si)-free base film 1, a silicon (Si)-containing film is first formed on the base film 1. Then, a gallium (Ga)-containing film is formed on the silicon (Si)-containing film. Here, the base film 1 may be a metal film made of a metal other than silicon (Si). For example, the base film 1 may be a metal film containing at least one of tungsten, iridium, osmium, rhodium, platinum, silver, rhenium, and palladium.

[0082] The following describes a method for forming a gallium (Ga)-containing film on a substrate 10 according to the method of the second embodiment, based on Figures 3(a) to 3(c). In this description, we will use the case where the gallium-containing film to be formed is a gallium nitride film 11 as an example.

[0083] As shown in Figure 3(a), a silicon (Si)-free underlayer film 1 may be formed on one side of the substrate 10. In this case, as shown in Figure 3(a), the underlayer film 1 may be formed on a portion of the substrate 10, while the underlayer film 1 may not be formed on other portions. Therefore, a portion of one side of the substrate 10 may be exposed, while other portions may be shielded by the underlayer film 1.

[0084] First, a silicon (Si)-containing film is formed on the lower film 1. Subsequently, since the gallium (Ga)-containing film to be formed is a gallium nitride film, a silicon nitride film 21 is formed on the lower film 1 as shown in Figure 3(b). The silicon nitride film 21 may be formed by either atomic layer deposition (ALD) or chemical vapor deposition (CVD). Furthermore, the silicon nitride film 21 may be formed on the substrate 10 by a wide variety of methods, without being limited to the above-described deposition method.

[0085] Then, as shown in Figure 3(c), a gallium nitride film 11 is formed on the silicon nitride film 21. At this time, the gallium nitride film 11 may be formed only on the upper part of the silicon nitride film 21, or the gallium nitride film 11 may also be formed on one side of the exposed substrate 10. At this time, the gallium nitride film 11 may be formed on the silicon nitride film 21 by the same method as described in the first embodiment. That is, the gallium nitride film 11 may be formed by either the atomic layer deposition (ALD) method or the chemical vapor deposition (CVD) method described in the section on the first embodiment.

[0086] Figure 4 shows a state in which a gallium (Ga)-containing film has been formed on a substrate by a method according to a modification of the second embodiment.

[0087] The method for forming the gallium nitride film 11 according to the second embodiment may include the steps of forming a first gallium nitride film 11a by atomic layer deposition (ALD) (first deposition method) and forming a second gallium nitride film 11b by chemical vapor deposition (CVD) (second deposition method), as described in the section on modifications of the first embodiment (ALD-CVD). Therefore, as shown in Figure 4, the first gallium nitride film 11a and the second gallium nitride film 11b can be laminated on a silicon nitride film to form a gallium nitride film 11.

[0088] Needless to say, the present invention is not limited in any way, and a method for forming a gallium nitride film 11 may include the steps of forming a first gallium nitride film 11a by a first evaporation method, forming a second gallium nitride film 11b by a second evaporation method, and forming a first gallium nitride film 11a by a first evaporation method (ALD-CVD-ALD).

[0089] Furthermore, the present invention is not limited in any way, and the steps of forming a first gallium nitride film 11a by a first evaporation method and forming a second gallium nitride film 11b by a second evaporation method may be performed alternately multiple times. That is, the method for forming the gallium nitride film 11 may include the steps of forming a first gallium nitride film 11a by a first evaporation method, forming a second gallium nitride film 11b by a second evaporation method, and forming a first gallium nitride film 11a by a first evaporation method and forming a second gallium nitride film 11b by a second evaporation method (ALD-CVD-ALD-CVD).

[0090] In the sections on the second embodiment and modifications of the second embodiment described above, the case in which a gallium nitride film 11 is formed on the lower film 1 was explained. However, the present invention is not limited thereto, and a gallium oxide film (GaO) may be formed on the lower film 1. In such a case, a silicon oxide (SiO) film is formed on the lower film 1, and a gallium oxide film is formed on the silicon oxide film. The method for forming the gallium oxide film on the silicon oxide film is the same as in the second embodiment and modifications of the second embodiment described above. The only difference is that an oxygen-containing reactant gas is used as the reactant gas.

[0091] The gallium nitride or gallium oxide film formed by the method according to the second embodiment and its modification may be a component of a power semiconductor device or a field-effect transistor. More specifically, the gallium nitride or gallium oxide film formed by the method according to the second embodiment and its modification may be an active layer or channel layer that is a component of a power semiconductor device.

[0092] Furthermore, gallium oxide films are applicable to the manufacture of overcurrent protection elements for power plants requiring ultra-high voltage or high power. That is, some components of an overcurrent protection element for a power plant requiring ultra-high voltage or high power may include a gallium oxide film formed by the method according to the embodiment.

[0093] Thus, a gallium nitride film or a gallium oxide film can be easily formed on a lower film 1 formed on a substrate 10 by the method according to the embodiment. That is, even if a silicon (Si)-free lower film 1 is formed in the region on one side of the substrate 10 where the gallium nitride film or gallium oxide film is to be formed, a gallium nitride film or gallium oxide film can be easily formed on the lower film 1. More specifically, in the embodiment, a silicon nitride film or silicon oxide film is first formed on the lower film 1 formed on the substrate 10, and then a gallium nitride film or gallium oxide film is grown on the silicon nitride film or silicon oxide film. Plasma is also generated when forming the silicon nitride film or silicon oxide film. As a result, a gallium nitride film or gallium oxide film grown in one direction can be formed. This suppresses or prevents the occurrence of defects in the gallium nitride film or gallium oxide film. This has the effect of improving the characteristics of devices to which the gallium nitride film or gallium oxide film is applied, such as power semiconductor elements.

[0094] Figure 5 is a schematic diagram showing a deposition apparatus for forming a gallium-containing film according to an embodiment of the present invention.

[0095] The deposition apparatus shown in Figure 5 will be described below. The deposition apparatus may be one that deposits a gallium nitride film or a gallium oxide film by atomic layer deposition (ALD) or chemical vapor deposition.

[0096] Referring to Figure 5, the deposition apparatus may include a chamber 100 and first and second gas injection units 300a and 300b provided inside the chamber 100 such that each of the support bases 200 provided inside the chamber 100 faces the support base 200, a gas supply unit 400 for supplying process gas to the first and second gas injection units 300a and 300b, and an antenna 610 equipped with a coil for inducing an electric field inside the chamber 100 to generate plasma, and a power supply unit 620 connected to the antenna 610.

[0097] The deposition apparatus may also include a heating unit 500 positioned opposite the support base 200, a drive unit 700 for raising, lowering, and rotating the support base 200, and an exhaust unit 800 for exhausting gas and impurities from inside the chamber 100.

[0098] The chamber 100 is a cylindrical structure having an internal space into which a thin film can be formed on a substrate 10 that has been brought inside, and may be dome-shaped, for example, as shown in Figure 5. More specifically, the chamber 100 may comprise a chamber body 110, an upper body 120 provided on the upper part of the chamber body 110, and a lower body 130 provided on the lower part of the chamber body 110. The chamber body 110 may be cylindrical with an open top and bottom, and the upper body 120 may be provided to cover the upper opening of the chamber body 110, and the lower body 130 may be provided to cover the lower opening of the chamber body 110. The upper body 120 may be dome-shaped with an inclined surface whose height gradually increases as it moves toward the center in its width direction. The lower body 130 may also be dome-shaped with an inclined surface whose height gradually decreases as it moves toward the center in its width direction. Such a chamber 100, that is, the chamber body 110 and each of the upper body 120 and lower body 130, may be made from a transparent material that allows light to pass through, for example, quartz.

[0099] The gas supply unit 400 may include a source gas supply unit 410 for supplying a source gas containing gallium, a first reactant gas supply unit 420a for supplying a reactant gas containing nitrogen, a second reactant gas supply unit 420b for supplying a reactant gas containing oxygen, a purge gas supply unit 430 for supplying purge gas, a hydrogen gas supply unit 440 for supplying hydrogen gas, and a discharge gas supply unit 450 for supplying a gas for discharge.

[0100] Furthermore, the gas supply unit 400 may also include a source gas supply unit 410, a first transport pipe 460a provided to connect the first and second reactant gas supply units 420a, 420b and the first gas injection unit 300a, a purge gas supply unit 430, and a second transport pipe 460b provided to connect the hydrogen gas supply unit 440 and the discharge gas supply unit 450 and the second gas injection unit 300b.

[0101] Furthermore, the gas supply unit 400 may include a source gas supply unit 410, a plurality of first connecting pipes 470a connecting the first and second reactant gas supply units 420a, 420b to the first transport pipe 460a, valves provided on each of the plurality of first connecting pipes 470a, a purge gas supply unit 430, a plurality of second connecting pipes 470b connecting the hydrogen gas supply unit 440 and the discharge gas supply unit 450 to the second transport pipe 460b, valves provided on each of the plurality of second connecting pipes 470b.

[0102] Furthermore, a gallium nitride film or gallium oxide film may be formed using the deposition apparatus shown in Figure 5. Below, a method for forming a gallium nitride film or gallium oxide film on a substrate by atomic layer deposition will be described based on Figure 5.

[0103] First, a gallium-containing source gas is injected into the chamber 100 using the source gas supply unit 410 and the first gas injection unit 300a. Then, the chamber 100 is purged by injecting purge gas into the chamber 100 using the purge gas supply unit 300 and the second gas injection unit 300b. Next, nitrogen-containing reactant gas or oxygen-containing reactant gas is injected into the chamber 100 using the first or second reactant gas supply units 420a, 420b and the first gas injection unit 300a. This forms a gallium nitride film or a gallium oxide film on the substrate 10. Then, the chamber 100 is purged by injecting purge gas into the chamber 100 using the purge gas supply unit 300 and the second gas injection unit 300b. This cycle can be repeated once or more times to form a gallium nitride film or a gallium oxide film on the substrate 10.

[0104] Furthermore, when injecting nitrogen-containing reactant gas or oxygen-containing reactant gas, a plasma may be formed inside the chamber 100. That is, when injecting the reactant gas, the discharge gas is injected together into the chamber 100 using the discharge gas supply unit 450 and the second gas injection unit 300b. Here, the discharge gas may be, for example, argon gas. When power is supplied to the antenna 610, a plasma can be formed inside the chamber 100. That is, the reactant gas is discharged to form a nitrogen plasma or an oxygen plasma.

[0105] Alternatively, a hydrogen plasma may be formed inside the chamber 100 after injecting a nitrogen-containing reactant gas or an oxygen-containing reactant gas. To this end, when the injection of the reactant gas is completed, hydrogen gas and discharge gas are injected into the chamber 100 using the hydrogen gas supply unit 440, the discharge gas supply unit 450, and the second gas injection unit 300b. Here, the discharge gas may be, for example, argon gas. When power is supplied to the antenna 610, a hydrogen plasma can be formed inside the chamber 100, thereby exposing the gallium nitride film or gallium oxide film to the hydrogen plasma. As a result, impurities can be removed from the gallium nitride film or gallium oxide film.

[0106] The above describes the formation of a gallium nitride film or a gallium oxide film by atomic layer deposition using the deposition apparatus shown in Figure 5. However, the present invention is not limited thereto, and a gallium nitride film or a gallium oxide film may also be formed by chemical vapor deposition using the deposition apparatus shown in Figure 5.

[0107] Furthermore, the deposition apparatus for forming the gallium nitride film or gallium oxide film is not limited in any way to the apparatus shown in Figure 5, and a wide variety of apparatuses can be used. [Industrial applicability]

[0108] According to embodiments of the present invention, a gallium nitride film or a gallium oxide film can be easily formed. That is, a gallium nitride film or a gallium oxide film can be grown in one direction on a silicon (Si) substrate. Therefore, a gallium nitride film or a gallium oxide film with suppressed defect formation can be formed. Consequently, the properties of the semiconductor device to which the gallium nitride film or gallium oxide film is applied are improved.

Claims

1. A method for forming a gallium-containing film on a substrate on which a metal film, a silicon (Si) film, and at least one of a silicon oxide (SiO) film and a silicon nitride (SiN) film are formed, The steps include preparing the circuit board and The steps include: injecting a gallium (Ga)-containing source gas onto the substrate; The steps include: injecting nitrogen (N)-containing reactant gas onto the substrate to form a first gallium nitride (GaN) film on top of at least one of the silicon film and silicon nitride film of the substrate; A method for forming a gallium-containing film, including the method described above.

2. The method for forming a gallium-containing film according to claim 1, wherein the step of injecting the reactant gas includes the step of forming a plasma using the reactant gas.

3. A method for forming a gallium-containing film according to claim 1, comprising the step of forming a first gallium nitride film, followed by the step of injecting a gallium (Ga)-containing source gas and a nitrogen (N)-containing reactant gas to form a second gallium nitride film on the first gallium nitride film.

4. The process includes the step of forming a third gallium nitride film on the second gallium nitride film, The step of forming the third gallium nitride film is: The steps include: injecting a gallium (Ga)-containing source gas onto the substrate; The steps include: injecting nitrogen (N)-containing reactant gas onto the substrate to form a third gallium nitride film on the second gallium nitride film; A method for forming a gallium-containing film according to claim 3, including the method described in claim 3.

5. The step includes forming a hydrogen plasma, The method for forming a gallium-containing film according to claim 1, wherein the step of forming the hydrogen plasma is performed between the step of injecting the gallium (Ga)-containing source gas and the step of injecting the nitrogen (N)-containing reactant gas.

6. The step includes forming a hydrogen plasma, The method for forming a gallium-containing film according to claim 1, wherein the step of forming the hydrogen plasma is performed after the step of injecting the nitrogen (N)-containing reactant gas is completed.

7. The method for forming a gallium-containing film according to claim 3, wherein the step of forming the second gallium nitride film includes the step of forming a plasma using the reactant gas.

8. The step includes forming a hydrogen plasma, The method for forming a gallium-containing film according to claim 3, wherein the step of forming the hydrogen plasma is performed after the step of forming a second gallium nitride film by injecting the gallium (Ga)-containing source gas and the nitrogen (N)-containing reactant gas.

9. A method for forming a gallium-containing film on a substrate on which a metal film, a silicon (Si) film, and at least one of a silicon oxide (SiO) film and a silicon nitride (SiN) film are formed, The steps include preparing the circuit board and The steps include: injecting a gallium (Ga)-containing source gas onto the substrate; The steps include: injecting an oxygen (O)-containing reactant gas onto the substrate to form a first gallium oxide (GaO) film on top of at least one of the silicon film and silicon oxide film of the substrate; A method for forming a gallium-containing film, including the method described above.

10. The method for forming a gallium-containing film according to claim 9, wherein the step of injecting the reactant gas includes the step of forming a plasma using the reactant gas.

11. A method for forming a gallium-containing film according to claim 9, comprising the step of forming a first gallium oxide film, followed by the step of injecting a gallium (Ga)-containing source gas and an oxygen (O)-containing reactant gas to form a second gallium oxide film on the first gallium oxide film.

12. The process includes the step of forming a third gallium oxide film on the second gallium oxide film, The step of forming the third gallium oxide film is: The steps include: injecting a gallium (Ga)-containing source gas onto the substrate; The steps include: injecting an oxygen (O)-containing reactant gas onto the substrate to form a third gallium oxide film on the second gallium oxide film; A method for forming a gallium-containing film according to claim 11, including the method described in claim 11.

13. The step includes forming a hydrogen plasma, The method for forming a gallium-containing film according to claim 9, wherein the step of forming the hydrogen plasma is performed between the step of injecting the gallium (Ga)-containing source gas and the step of injecting the oxygen (O)-containing reactant gas.

14. The step includes forming a hydrogen plasma, The method for forming a gallium-containing film according to claim 9, wherein the step of forming the hydrogen plasma is performed after the step of injecting the oxygen (O)-containing reactant gas is completed.

15. The method for forming a gallium-containing film according to claim 11, wherein the step of forming the second gallium oxide film includes the step of forming a plasma using the reactant gas.

16. The step includes forming a hydrogen plasma, The method for forming a gallium-containing film according to claim 11, wherein the step of forming the hydrogen plasma is performed after the step of forming a second gallium oxide film by injecting the gallium (Ga)-containing source gas and the oxygen (O)-containing reactant gas.

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