Gallium nitride film, method for producing same, laminated substrate, semiconductor element, and electronic apparatus

Abstract

Provided are a gallium nitride film having high electroconductivity even without heat treatment at a high temperature, a method for producing the gallium nitride film, a laminated substrate, a semiconductor element, and an electronic apparatus.　The gallium nitride film contains hydrogen. The hydrogen content may be 1.0 × 1019 atoms / cm3 or higher. The gallium nitride film may contain a dopant. The dopant content may be 1.0 × 1020 atoms / cm3 or higher.

Description

Gallium nitride film, its manufacturing method, laminated substrate, semiconductor element, and electronic device

[0001] The present disclosure relates to a gallium nitride film, a method for producing the same, a laminated substrate, a semiconductor element, and an electronic device.

[0002] Gallium nitride films are used in semiconductor devices such as LEDs and transistors, and are often required to have high electrical conductivity. For example, a silicon-doped gallium nitride film formed on a substrate such as a wafer by pulse sputtering deposition (PSD) is known as such a gallium nitride film (see, for example, Non-Patent Document 1).

[0003] Applied Physics Express 14,051011 (2021)

[0004] However, the gallium nitride film described in Non-Patent Document 1 above sometimes does not have sufficient conductivity. Even such a gallium nitride film can have its conductivity increased by undergoing a heat treatment such as annealing at a high temperature. However, in such a case, in a semiconductor device including a gallium nitride film, not only the gallium nitride film but also the electrodes, substrate, and other components are subjected to a heat treatment at a high temperature, which can easily cause melting of the electrodes, warping of the substrate, and distortion of the entire semiconductor device.

[0005] The present disclosure aims to provide at least one of a gallium nitride film that has high conductivity without heat treatment at high temperatures, a method for producing the same, a laminate substrate, a semiconductor element, and an electronic device.

[0006] The present invention relates to a gallium nitride film containing hydrogen, and a method for manufacturing the same, comprising the steps of: forming a gallium nitride film containing hydrogen in a gallium nitride film; １９ atoms / cm ３(3) The gallium nitride film according to (1) or (2), having a surface roughness Ra of 5 nm or less. (4) The gallium nitride film according to any one of (1) to (3), containing a dopant. (5) The gallium nitride film according to (4), wherein the dopant is an n-type dopant. (6) The gallium nitride film according to (4), wherein the content of the dopant is 1.0 × 10 ２０ atoms / cm ３ (7) The gallium nitride film according to any one of (1) to (6), having a film thickness of 1000 nm or less. (8) A method for producing a gallium nitride film, comprising a film formation step of producing a hydrogen-containing gallium nitride film on a substrate by sputtering a sputtering target containing gallium nitride in an atmosphere containing hydrogen. (9) The method for producing a gallium nitride film according to (8), wherein the hydrogen-containing atmosphere is an atmosphere containing hydrogen and at least one of argon and nitrogen. (10) The method for producing a gallium nitride film according to (8) or (9), wherein the temperature of the substrate is set to 600° C. or less. (11) A layered substrate comprising the gallium nitride film according to any one of (1) to (7) and a substrate. (12) A semiconductor element comprising the layered substrate according to (11). (13) An electronic device comprising the semiconductor element according to (12).

[0007] According to the present disclosure, there are provided at least one of a gallium nitride film having high conductivity without heat treatment at high temperatures, a method for producing the same, a laminated substrate, a semiconductor element, and an electronic device.

[0008] Fig. 1 is a cross-sectional view showing an embodiment of a laminated substrate according to the present disclosure, and Fig. 2 is a schematic diagram showing an embodiment of an electronic device according to the present disclosure.

[0009] The following describes in detail an embodiment of the present disclosure by way of an example. However, the present disclosure is not limited to the following embodiment. Furthermore, any combination of the configurations disclosed herein and any combination of the upper and lower limits of the numerical values ​​are included.

[0010] <Gallium Nitride Film> First, one embodiment of the gallium nitride film of the present disclosure will be described.

[0011] The gallium nitride film (hereinafter also referred to as "GaN film") of the present disclosure is a GaN film containing hydrogen, and is preferably a sputtered GaN film containing hydrogen. A GaN film containing hydrogen has high conductivity even without high-temperature heat treatment. Therefore, high-temperature heat treatment to increase conductivity (i.e., to reduce resistivity) is not required for the GaN film. One of the reasons why a GaN film containing hydrogen has high conductivity even without high-temperature heat treatment is thought to be that hydrogen blocks defects contained in the crystal lattice of gallium nitride, making it difficult for electrons to be trapped in the defects. In other words, a GaN film that has not been heat-treated at high temperatures has low crystallinity and has many defects in the crystal lattice. When a voltage is applied to such a GaN film, electrons are trapped in the defects, preventing their movement. When a GaN film contains hydrogen, hydrogen blocks the defects, making it difficult for electrons to be trapped in the defects when a voltage is applied to the GaN film, and it is thought that this increases the conductivity of the GaN film.

[0012] The GaN film of this embodiment will be described in detail below.

[0013] (Hydrogen) The GaN film of this embodiment contains hydrogen (H). "Containing hydrogen" means that the hydrogen content is 0.5×10 in secondary ion mass spectrometry (SIMS) as described below. １８ atoms / cm ３ This means that more hydrogen than this is detected.

[0014] The hydrogen content of the GaN film is not particularly limited. From the viewpoint of further increasing the conductivity of the GaN film, the hydrogen content is preferably 1×10 １９ atoms / cm ３ That's it, 1 x 10 ２０ atoms / cm ３ That's it, 3 x 10 ２０ atoms / cm ３ or more or 5 x 10 ２０ atoms / cm ３ The hydrogen content of the GaN film is preferably 1×10 ２２ atoms / cm ３ Below, 5 x 10 ２１atoms / cm ３ Below, 2 x 10 ２１ atoms / cm ３ or less or 1 x 10 ２１ atoms / cm ３ The upper and lower limits of the hydrogen content of the GaN film may be any combination of the above, but may be 1×10 １９ atoms / cm ３ 1x10 or more ２２ atoms / cm ３ Below, 1 x 10 ２０ atoms / cm ３ 5x10 or more ２１ atoms / cm ３ Below, 3 x 10 ２０ atoms / cm ３ 5x10 or more ２１ atoms / cm ３ or less, or 5 x 10 ２０ atoms / cm ３ 2x10 or more ２１ atoms / cm ３ It is preferable that the hydrogen content is equal to or less than 10 ... ３ " is 1 cm ３ The hydrogen content of a GaN film refers to the smallest hydrogen content among the hydrogen contents measured continuously along the depth direction (film thickness direction) using SIMS for the entire film thickness from one surface to the opposite surface of the GaN film. The more measurement points in the SIMS measurement, the more preferable. Measurements are preferably performed at 5 or more or 10 or more points per 100 nm, and more preferably at 20 or more, 30 or more, or 50 or more points per 100 nm. A specific number of measurement points in the SIMS measurement can be 50 to 200 points per 100 nm.

[0015] (Surface Roughness Ra) The surface roughness Ra of the GaN film is not particularly limited, and can be 5 nm or less, or may be greater than 5 nm. Ra is preferably 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, or 1.5 nm or less. Ra is one index indicating the surface smoothness of a GaN film. An Ra of 5 nm or less further improves the surface smoothness of the GaN film, suppressing scattering of electrons and holes that serve as charge carriers, and further suppressing degradation of the performance of semiconductor elements and electronic devices. Ra may be 0 nm or more, more than 0 nm, 0.1 nm or more, 0.5 nm or more, or 1 nm or more. Examples of Ra of the GaN film of this embodiment include 0 nm or more to 5 nm or less, more than 0 nm to 5 nm or less, 0.1 nm or more to 3 nm or less, 1 nm or more to 3 nm or less, 1 nm or more to 2 nm or less, or 1 nm or more to 1.5 nm or less. The surface roughness Ra represents the arithmetic average roughness. The surface roughness Ra can be measured using a general scanning probe microscope (for example, SPM-9600 scanning probe microscope manufactured by Shimadzu Corporation).

[0016] (Dopant) The GaN film may contain a dopant. By containing a dopant in the GaN film, the conductivity of the GaN film can be further improved. The dopant may be at least one of an n-type dopant and a p-type dopant, and is preferably an n-type dopant. Examples of n-type dopants include one or more selected from the group consisting of silicon, germanium, and tin, and silicon is preferred. Examples of p-type dopants include one or more selected from the group consisting of magnesium, zinc, and cadmium. The GaN film may contain a single dopant element or may contain two or more dopant elements.

[0017] The dopant content of the GaN film is not particularly limited as long as the GaN film exhibits p-type or n-type characteristics. However, from the viewpoint of further increasing the conductivity of the GaN film, it is preferable that the dopant content be 1×10 １８ atoms / cm ３ That's it, 1 x 10 １９ atoms / cm ３ That's it, 1 x 10 ２０ atoms / cm ３or more or 1.2 x 10 ２０ atoms / cm ３ The dopant content of the GaN film is preferably 1×10 ２２ atoms / cm ３ Below, 5 x 10 ２１ atoms / cm ３ Below, 2 x 10 ２１ atoms / cm ３ or less or 1 x 10 ２１ atoms / cm ３ The upper and lower limits of the dopant content of the GaN film may be any combination of the above, but may be 1×10 １８ atoms / cm ３ 1x10 or more ２２ atoms / cm ３ Below, 1 x 10 １９ atoms / cm ３ 5x10 or more ２１ atoms / cm ３ Below, 1 x 10 ２０ atoms / cm ３ 2x10 or more ２１ atoms / cm ３ or less, or 1.2 x 10 ２０ atoms / cm ３ 1x10 or more ２１ atoms / cm ３ It is preferable that the dopant content is not more than 10 ... ３ " is 1 cm ３ The dopant content of a GaN film refers to the smallest dopant content among the dopant contents measured continuously along the depth direction using SIMS for the entire film thickness from one surface to the opposite surface of the GaN film. The more measurement points in the SIMS measurement, the more preferable. It is preferable to measure at least 5 or 10 points for the entire film thickness, and more preferably at least 20, 30, or 50 points per 100 nm. A specific number of measurement points in the SIMS measurement can be 50 to 200 points for the entire film thickness.

[0018] (Thickness) The thickness of the GaN film is not particularly limited as long as it is a thickness that can be used as a semiconductor element or the like, and may be 1000 nm or less, 500 nm or less, 200 nm or less, 150 nm or less, or 100 nm or less. Furthermore, the thickness of the GaN film is preferably 10 nm or more, 20 nm or more, 30 nm or more, 40 nm or more, or 50 nm or more. The upper and lower limits of the thickness may be any combination of the above, but are preferably 10 nm or more to 1000 nm or less, 20 nm or more to 200 nm or less, 50 nm or more to 200 nm or less, 30 nm or more to 150 nm or less, or 50 nm or more to 100 nm or less. (Resistivity) The GaN film has high conductivity, and its resistivity is 1 Ωcm or less, 5×10 －１ Ωcm or less, or 5 x 10 －２ The resistivity is preferably low, but it is preferably 1×10 －４ Ωcm or more, 1×10 －３ Ωcm or more or 1×10 －２ The resistivity of GaN in this embodiment may be, for example, 1×10 －４ Ωcm or more and 1Ωcm or less, 1×10 －３ Ωcm or more 5 x 10 －１ Ωcm or less, or 1 x 10 －２ Ωcm or more 5 x 10 －２ The resistivity is a value that can be measured using a general Hall effect measuring device (for example, 8403 AC / DC Hall effect measuring device, manufactured by Toyo Corporation).

[0019] <Layered Substrate> Next, one embodiment of the layered substrate of the present disclosure will be described with reference to FIG. 1 . As shown in FIG. 1 , the layered substrate 100 includes a substrate 10 and a GaN film 20, and has a structure in which the GaN film 20 is layered directly on the substrate 10. The layered substrate 100 can also be considered a substrate (film-coated substrate) including a GaN film. The GaN film 20 is composed of the GaN film described above. The layered substrate 100 eliminates the need for high-temperature heat treatment on the GaN film 20 to increase its conductivity, and therefore eliminates the need for high-temperature heat treatment on the layered substrate 100 including the GaN film 20. In other words, high-temperature heat treatment is not required not only for the GaN film 20 but also for the substrate 10. Therefore, the layered substrate 100 can reduce the risk of warping of the substrate 10 and distortion throughout the layered substrate 100.

[0020] (Substrate) The substrate 10 is not particularly limited as long as it is a substrate (base material) used for semiconductor applications, etc. Examples of the substrate 10 include a sapphire substrate, a silicon substrate, a gallium nitride substrate, a silicon carbide substrate, a glass substrate, a quartz substrate, a polyimide substrate, or a polyethylene terephthalate substrate, with a sapphire substrate being preferred. The surface roughness Ra of the substrate 10 is not particularly limited, but is preferably 10 nm or less, 1 nm or less, 0.5 nm or less, or 0.1 nm or less. The surface roughness Ra of the substrate 10 may be 0 nm or more or 0.01 nm or more, and may be 0 nm or more to 10 nm or less, 0.01 nm or more to 0.5 nm or less, or 0.01 nm or more to 0.1 nm or less.

[0021] <GaN Film Manufacturing Method> The GaN film manufacturing method of the present disclosure includes a film formation step in which a hydrogen-containing GaN film is produced on a substrate by sputtering a sputtering target containing GaN in a hydrogen-containing atmosphere. The GaN film manufacturing method of the present disclosure may further include a preparation step before the film formation step. Note that, because a laminated substrate is obtained by the GaN film manufacturing method of the present disclosure, the GaN film manufacturing method of the present disclosure can also be referred to as a laminated substrate manufacturing method, and can also be considered as a GaN film formation method or a GaN film formation method. According to the GaN film manufacturing method of the present disclosure, a GaN film having high conductivity can be produced without heat treatment at high temperatures. Furthermore, a GaN film having high conductivity can be produced even when the substrate temperature is low in the film formation step.

[0022] (1) Preparation Step In the preparation step, it is preferable to evacuate the inside of the film formation apparatus. The degree of vacuum (ultimate vacuum) in the film formation apparatus is not particularly limited as long as it is a vacuum degree that allows the formation of the GaN film to proceed. －５ Pa or less, and even 1×10 －５ Pa or less, or even 5×10 －６ It is preferable that the vacuum level is 3×10 Pa or less. －５ By keeping the pressure at or below 0 Pa, residual gases are less likely to be mixed in as impurities during film formation, and the crystallinity of the GaN film is further improved. In the film formation apparatus, it is preferable to perform a baking process on the film formation apparatus before evacuating the apparatus in order to remove residual gases. The degree of vacuum should be greater than 0 Pa and less than 1×10 －８ Pa or more, or 1 x 10 －７ For example, the pressure is 0 Pa or more, and the pressure is 3×10 －５ Pa or less, 1×10 －８ Pa or more 1×10 －５ Pa or less, or 1 x 10 －７ Pa or more 5×10 －６ Pa or less.

[0023] In addition, in the preparation step, it is preferable to pretreat the substrate. Pretreatment removes organic layers and irregularities on the substrate surface, facilitating epitaxial growth. Examples of pretreatment methods include one or more methods selected from the group consisting of reverse sputtering, acid treatment, and UV treatment. From the viewpoint of preventing re-adhesion of impurities after treatment, reverse sputtering is preferable. Reverse sputtering is a method of cleaning the substrate surface by bombarding the substrate with plasma-converted atoms. This enables film formation with reduced impurities and irregularities on the substrate surface. To prevent reverse sputtered impurities from adhering to the film formation chamber, it is preferable to perform the reverse sputtering in a chamber separate from the film formation chamber. Gas species (sputtering gas) used in the reverse sputtering can include one or more selected from the group consisting of argon, nitrogen, and oxygen. A sputtering gas containing oxygen is preferable, as it facilitates removal of carbon-based impurities from the substrate surface. The oxygen content is preferably 1% to 10%, with the total gas pressure being 100%. The treatment time for the reverse sputtering process is preferably 30 seconds or more and 900 seconds or less, or 60 seconds or more and 300 seconds or less. This allows impurities on the surface of the substrate to be removed while providing the surface of the substrate with a surface roughness (Ra) suitable for forming a GaN film. The reverse sputtering process may be carried out, for example, at 100 W, with a sputtering gas of Ar: 29 sccm (1 atm, 25°C), and O ２ : 1 sccm (1 atm 25° C.) for 60 seconds.

[0024] In the preparation step, it is preferable to hold the substrate at the temperature planned for film formation for a certain period of time. This makes the temperature of the substrate uniform before film formation, and further improves the crystallinity of the GaN film that is the film formed. For example, the holding time is preferably 1 minute or more, 5 minutes or more, or 10 minutes or more. On the other hand, from the viewpoint of improving productivity, the holding time is preferably 1 hour or less, or 30 minutes or less. The holding time in the preparation step may be 1 minute or more and 1 hour or less, or 10 minutes or more and 30 minutes or less.

[0025] (2) Film Formation Process (Sputtering Target) A GaN-containing sputtering target (hereinafter simply referred to as "target") may contain GaN, or may be made of GaN. When forming a GaN film containing a dopant, the target may contain the dopant or may be made of GaN containing the dopant. To obtain the effect of the dopant, it is preferable that the amount of metal element impurities other than the dopant is small, and it is preferable that the purity when using the amount of metal element impurities excluding the dopant is 99.99% or more. The amount of metal element impurities in the target can be measured by GDMS. The target may contain hydrogen, but it does not have to contain hydrogen. To improve the crystallinity of the entire GaN film, the target preferably has an oxygen content of less than 3 atm%, more preferably 1 atm% or less. The target preferably has a low metal impurity content. Specifically, the metal impurity content is preferably less than 0.1 mass% or less than 0.01 mass%. The area of ​​the target is not particularly limited, but is preferably 18 cm ２ or more, or 100 cm ２ The larger the target area, the more stable the discharge becomes, enabling sputtering at lower gas pressure and lower discharge density. Furthermore, the uniformity of the film thickness and quality is improved. The target area is 10,000 cm ２ Below, 5000cm ２ or less than 1000 cm ２ The following can be exemplified.

[0026] (Sputtering) The sputtering method may be one or more selected from the group consisting of DC sputtering, RF sputtering, AC sputtering, DC magnetron sputtering, RF magnetron sputtering, ECR sputtering, pulsed laser deposition deposition, and ion beam sputtering. Among these, at least one of DC magnetron sputtering and RF magnetron sputtering is preferred because it allows for uniform deposition over a large area at high speed.

[0027] The gas pressure during sputtering (film formation pressure) is not particularly limited, but may be, for example, 1.5 Pa or less, 1.0 Pa or less, or 0.6 Pa or less. The lower the gas pressure during sputtering, the more easily particles emitted from the target reach the substrate while maintaining their high energy, and the more easily they are epitaxially rearranged. The gas pressure during sputtering may be, for example, 0 Pa or more, or 0.1 Pa or more. The lower the gas pressure during sputtering, the more easily particles emitted from the target (sputtered particles) reach the substrate while maintaining their high energy, and the more easily they are epitaxially rearranged on the substrate. The gas pressure during sputtering may be, for example, 0 Pa or more to 1.0 Pa or less, 0.1 Pa or more to 1.0 Pa or less, 0 Pa or more to 0.6 Pa or less, or 0.1 Pa or more to 0.6 Pa or less.

[0028] (Substrate) The substrate may be the same as the substrate 10. Film formation is preferably performed while the substrate is heated. By forming the film while the substrate is heated, energy is imparted to the sputtered particles, allowing the GaN film to have a more stable crystalline state, and cracking of the substrate due to differences in thermal expansion coefficients during high-temperature heat treatment can be prevented. The substrate temperature during film formation is preferably 600°C or less, or 550°C or less. The substrate temperature may be room temperature or higher, 100°C or higher, or 400°C or higher. A substrate temperature of 100°C or higher tends to increase the crystallinity of the GaN film and reduce defects, making it easier to increase the conductivity of the GaN film even with a small amount of hydrogen. Furthermore, a substrate temperature of 400°C or higher allows the GaN particles, which are particularly sputtered particles, to be aligned with good crystallinity in the GaN film. The substrate temperature is preferably room temperature or higher and 600°C or lower, 100°C or higher and 600°C or lower, or 400°C or higher and 550°C or lower.

[0029] (Atmosphere) The sputtering atmosphere may contain hydrogen (a hydrogen-containing atmosphere may be used), and hydrogen (H ２) alone, or may be composed of a mixed gas of hydrogen and another gas. By sputtering in a hydrogen-containing atmosphere, the GaN film of this embodiment can be formed even when a target not containing hydrogen is used. From the viewpoint of enhancing safety, the hydrogen-containing atmosphere is preferably composed of a mixed gas of hydrogen and another gas. The other gas is preferably an inert gas. An inert gas does not react with hydrogen to produce hydrogen compounds, making it easier to introduce hydrogen into the GaN film. Examples of the inert gas include at least one of argon and nitrogen. These may be used alone or in combination of two or more. This allows for the formation of a hydrogen-containing atmosphere containing at least one of argon and nitrogen. The inert gas preferably contains nitrogen. This allows for the production of a GaN film with fewer nitrogen defects. The inert gas is preferably composed of argon and nitrogen. This allows for the formation of a hydrogen-containing atmosphere containing argon and nitrogen. On the other hand, the inert gas is preferably composed of nitrogen alone. This allows for the formation of a nitrogen-containing hydrogen-containing atmosphere, making it easier to form a hydrogen-containing GaN film more inexpensively than a hydrogen-containing atmosphere containing argon.

[0030] A hydrogen-containing atmosphere containing argon and nitrogen can be formed, for example, by separately supplying a mixed gas containing hydrogen and argon and nitrogen gas. The atmosphere may be formed by separately supplying a mixed gas containing hydrogen and nitrogen and argon gas, or by supplying a mixed gas containing hydrogen, nitrogen, and argon gas. A hydrogen-containing atmosphere containing nitrogen can be formed, for example, by supplying a mixed gas containing hydrogen and nitrogen, or it can also be formed by separately supplying hydrogen gas and nitrogen gas.

[0031] When the hydrogen-containing atmosphere is formed by separately supplying a mixed gas containing hydrogen and argon and nitrogen gas, the hydrogen content in the mixed gas is not particularly limited as long as it is greater than 0% by volume, but is preferably 1% by volume or more, 2% by volume or more, or 3% by volume or more. The hydrogen content in the mixed gas may be 99% by volume or less, 80% by volume or less, or 4% by volume or less. The hydrogen content in the mixed gas is preferably 1% by volume or more and 99% by volume or less, 2% by volume or more and 80% by volume or less, 2% by volume or more and 4% by volume or less, or 3% by volume or more and 4% by volume or less.

[0032] As long as a hydrogen-containing atmosphere is formed, the flow rate ratio (partial pressure ratio) R of the mixed gas to nitrogen gas is not particularly limited, but may be 0.2 or more, and preferably 0.6 or more, 1 or more, or 2 or more. When the flow rate ratio R is 0.2 or more, the conductivity of the obtained GaN film can be further increased. The flow rate ratio R may be 5 or less, 4 or less, or 3.5 or less. The flow rate ratio R is preferably 0.2 or more and 5 or less, 0.6 or more and 5 or less, 1 or more and 4 or less, or 2 or more and 3.5 or less.

[0033] The discharge density during discharge is 0.01 W / cm ２ More than 5W / cm ２ Below, 0.01W / cm ２ 1W / cm or more ２ The following is preferable. The discharge density is calculated by dividing the power applied during discharge by the area of ​​the target surface. When the discharge density during discharge is 5 W / cm ２ If the discharge density is less than 0.01 W / cm, coarse single crystal particles are less likely to peel off from the target due to the power applied to the target. ２ When the plasma is stable, discharge becomes easy, and the film formation rate increases, improving film productivity. Furthermore, the energy during sputtering is high, improving adhesion during film formation.

[0034] The deposition time may be adjusted appropriately depending on the thickness of the GaN film. The longer the deposition time, the thicker the GaN film can be. The deposition time may be, for example, 1 minute or more, or 10 minutes or more, and 90 minutes or less, 60 minutes or less, or 30 minutes or less, and is preferably 1 minute or more and 90 minutes or less, 10 minutes or more and 60 minutes or less, or 10 minutes or more and 30 minutes or less.

[0035] <Semiconductor Element> The semiconductor element of the present disclosure includes a GaN film. The semiconductor element of the present disclosure may further include an electrode. According to the semiconductor element of the present disclosure, high-temperature heat treatment for increasing the conductivity of the GaN film is not required, and therefore high-temperature heat treatment is not required for the semiconductor element including the GaN film. In other words, high-temperature heat treatment is not required not only for the GaN film but also for the electrode, substrate, and other components. Therefore, the semiconductor element can be made less susceptible to melting of the electrode, warping of the substrate, and distortion of the entire semiconductor element.

[0036] The present disclosure is particularly useful for semiconductor devices having electrodes containing a low-melting-point metal such as aluminum, because if the electrodes contain a low-melting-point metal, the semiconductor device may not be heat-treated at high temperatures to avoid melting the electrodes.

[0037] Examples of semiconductor elements include light-emitting elements such as blue light-emitting diodes (LEDs) and blue laser diodes (LDs), and power devices such as diodes and transistors.

[0038] <Electronic Device> Next, one embodiment of an electronic device according to the present disclosure will be described with reference to Fig. 2. As shown in Fig. 2, electronic device 300 includes semiconductor element 200, which includes laminated base material 100. According to electronic device 300, semiconductor element 200 can reduce the occurrence of electrode melting, substrate warpage, and distortion throughout semiconductor element 200, thereby suppressing performance degradation of electronic device 300. Examples of electronic device 300 include mobile devices such as mobile phones, computers such as servers, power conversion devices such as AC-DC converters, transportation equipment such as automobiles, and aircraft such as drones.

[0039] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to the following examples.

[0040] Examples 1 to 6 First, a sapphire substrate (off-axis angle: none, surface roughness Ra: 0.09 nm, diameter: 50.8 mm (2 inches)) manufactured by Shinkosha Co., Ltd. was prepared as a film-forming substrate. At this time, the surface of the sapphire substrate was set to be the (0001) plane.

[0041] On the other hand, a Si-doped GaN sputtering target was prepared by mixing silicon (Si) powder and GaN powder and sintering the mixture. The substrate and the GaN sputtering target were then placed in a magnetron sputtering apparatus.

[0042] The target-substrate distance was set to 150 mm, and the ultimate vacuum was increased by baking the chamber before film formation.

[0043] Next, at the start of sputtering, plasma was ignited using nitrogen gas with the substrate-side shutter closed. Pre-sputtering was performed for 10 minutes under the same conditions as during film formation to stabilize the discharge. The shutter-to-substrate distance was 5 mm. A 3-inch diameter shutter was used. The substrate was then heated to 500°C, and a hydrogen-containing atmosphere containing argon and nitrogen was formed while introducing hydrogen-added Ar gas (a mixture of hydrogen and argon) and nitrogen gas as sputtering gas into the chamber. A GaN film was then formed on the substrate by sputtering a GaN sputtering target under the film formation conditions listed in Table 1. In Examples 1 to 6, the hydrogen-added Ar gas in the sputtering gas contained 3% hydrogen by volume.

[0044] (Example 7) A GaN film was produced in the same manner as in Example 1, except that the sputtering gas introduced into the chamber consisted solely of a mixed gas of hydrogen and nitrogen (hydrogen-added nitrogen) containing 3% by volume of hydrogen, forming a hydrogen-containing atmosphere containing nitrogen. (Comparative Example 1) A GaN film was produced in the same manner as in Example 1, except that the sputtering gas introduced into the chamber consisted solely of nitrogen gas.

[0045] <Characteristics> The GaN film was evaluated as follows, and the results are shown in Table 2.

[0046] (Thickness of GaN Film) Using a step gauge DektakXT (manufactured by Bruker), the step between the film-formed portion and the non-film-formed portion was measured as the thickness (film thickness) of the GaN film.

[0047] (Hydrogen Content) Using SIMS, the hydrogen content was measured continuously along the depth direction from the surface of the GaN film. The smallest hydrogen content among the series of hydrogen contents measured for the entire film thickness from the surface of the GaN film to the substrate-side edge (substrate-side surface) was taken as the hydrogen content in the GaN film. The number of measurement points relative to the entire film thickness was 68 points in Example 1, 57 points in Example 2, 74 points in Example 3, 77 points in Example 4, 144 points in Example 5, 160 points in Example 6, 60 points in Example 7, and 168 points in Comparative Example 1.

[0048] (Dopant Content) Using SIMS, the dopant (silicon) content was measured continuously along the depth direction from the surface of the GaN film. The smallest dopant content among the series of dopant contents measured for the entire film thickness from the surface of the GaN film to the substrate side edge (substrate side surface) was taken as the dopant content in the GaN film. The number of measurement points relative to the entire film thickness was 68 points in Example 1, 57 points in Example 2, 74 points in Example 3, 77 points in Example 4, 144 points in Example 5, 160 points in Example 6, 60 points in Example 7, and 168 points in Comparative Example 1, respectively.

[0049] <Conductivity> The conductivity of the GaN film was measured using resistivity as an index, using a 8403-type AC / DC Hall effect measuring device (manufactured by Toyo Corporation).

[0050] <Smoothness> The surface roughness Ra of the GaN film was used as an index for the surface smoothness. The Ra of the GaN film was measured using an SPM-9600 scanning probe microscope (manufactured by Shimadzu Corporation).

[0051]

[0052] From the results shown in Table 2, the GaN films of Examples 1 to 7 had a maximum resistivity of 1.01 × 10 －１ (Ωcm), whereas the GaN film of Comparative Example 1 had a resistivity of 6.88×10 ３ (Ωcm). From the above, it was confirmed that the GaN film of the present disclosure has low resistivity and high conductivity even without heat treatment at high temperatures. The entire contents of the specifications, claims, drawings and abstracts of Japanese Patent Application No. 2023-171488 filed on October 2, 2023 and Japanese Patent Application No. 2024-045754 filed on March 21, 2024 are hereby incorporated by reference as the disclosure of the specification of the present disclosure.

[0053] 10...substrate, 20...GaN film, 100...laminated base material, 200...semiconductor element, 300...electronic device.

Claims

1. Hydrogen-containing gallium nitride film.

2. The hydrogen content is 1.0 x 10 １９ atoms / cm ３ The gallium nitride film according to claim 1 .

3. The gallium nitride film according to claim 1, having a surface roughness Ra of 5 nm or less.

4. The gallium nitride film according to any one of claims 1 to 3, which contains a dopant.

5. The gallium nitride film of claim 4, wherein said dopant is an n-type dopant.

6. The content of the dopant is 1.0×10 ２０ atoms / cm ３ The gallium nitride film according to claim 4 or 5.

7. A gallium nitride film according to any one of claims 1 to 6, having a thickness of 1000 nm or less.

8. A method for producing a gallium nitride film, comprising a film formation step of producing a gallium nitride film containing hydrogen on a substrate by sputtering a sputtering target containing gallium nitride in an atmosphere containing hydrogen.

9. The method for producing a gallium nitride film according to claim 8, wherein the hydrogen-containing atmosphere is an atmosphere containing hydrogen and at least one of argon and nitrogen.

10. The method for producing a gallium nitride film according to claim 8 or 9, wherein the temperature of the substrate is set to 600° C. or less.

11. A layered substrate comprising the gallium nitride film according to any one of claims 1 to 7 and a substrate.

12. A semiconductor device comprising the laminated substrate according to claim 11.

13. An electronic device comprising the semiconductor element according to claim 12.

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