CN-121992505-A - Gallium nitride single crystal substrate and method for producing same

Abstract

A gallium nitride single crystal substrate and a method for manufacturing the same. The object is to reduce the resistivity of a gallium nitride single crystal substrate and maintain high thermal conductivity even in a high-temperature environment. A gallium nitride single crystal substrate having a low-index crystal plane (0001) closest to a main surface, wherein the gallium nitride single crystal substrate has a resistivity of 1 x 10 ‑2 Ω & cm or less at 200 ℃ and a thermal conductivity of 80W/mk or more in the thickness direction at 200 ℃.

Inventors

• HARUKI HIROYUKI
• SATO TAKASHI
• Kitamura Hisarang
• FUJIMOTO TETSUHIRO

Assignees

• 住友化学株式会社

Dates

Publication Date

20260508

Application Date

20251027

Priority Date

20241101

Claims (6)

1. 1. A gallium nitride single crystal substrate, which is a gallium nitride single crystal substrate having a low-index crystal plane (0001) plane nearest to a main surface, The gallium nitride single crystal substrate has a resistivity of 1X 10 -2 Ω & cm or less at 200 ℃, The thermal conductivity in the thickness direction at 200 ℃ is 80W/mk or more.
2. 2. The gallium nitride single crystal substrate according to claim 1, wherein a thermal conductivity in a thickness direction at 25 ℃ is 120W/mk or more and 230W/mk or less.
3. 3. The gallium nitride single crystal substrate according to claim 2, wherein when the thermal conductivity in the thickness direction at 200 ℃ is R (H) and the thermal conductivity in the thickness direction at 25 ℃ is R (L), R (H) and R (L) satisfy (R (L) -R (H))/R (L). Ltoreq.0.5.
4. 4. A gallium nitride single crystal substrate according to claim 1 or claim 2, comprising an impurity containing germanium, The germanium concentration is 1.0X10 18 cm -3 or more.
5. 5. The gallium nitride single crystal substrate according to claim 4, wherein the impurity contains oxygen, The oxygen concentration is less than 1/10 of the germanium concentration.
6. 6. A method for producing a gallium nitride single crystal substrate, comprising the steps of: (a) A step of preparing a base substrate formed of a gallium nitride single crystal having a low-index crystal plane (0001) closest to the main surface, and (B) A step of epitaxially growing a gallium nitride single crystal on the main surface of the base substrate, In the (b), a source gas for forming the gallium nitride single crystal is supplied to the base substrate under an ammonia-containing atmosphere having a growth pressure of 1atm or more and 1.5atm or less, and ammonia is supplied from the periphery of a support member that supports the base substrate.

Description

Gallium nitride single crystal substrate and method for producing same Technical Field The present invention relates to a gallium nitride single crystal substrate and a method for producing the same. Background Group III nitride semiconductors typified by gallium nitride (GaN) are widely used as materials constituting semiconductor devices such as light-emitting devices and electronic devices. In order to improve the quality (semiconductor characteristics and the like) of a semiconductor device made of a group III nitride semiconductor, it is desirable to manufacture a semiconductor laminate or a nitride semiconductor self-supporting substrate for manufacturing the semiconductor device with good crystal quality. GaN single crystal substrates are doped with impurities, and it is sought to reduce their resistivity. In particular, in the application of high-power laser diodes and power devices, further reduction of the resistivity of GaN single crystal substrates is demanded. From the viewpoint of lowering the resistivity, it is necessary to increase the impurity concentration. As this impurity, germanium (Ge) has been studied in view of the fact that GaN is not easily deteriorated in crystallinity even at a high concentration (for example, patent document 1). Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2021-195280 Disclosure of Invention Problems to be solved by the invention However, the GaN single crystal substrate is sometimes mounted on a heat sink when manufacturing a semiconductor device. A GaN single crystal substrate used in a semiconductor device is required to have high thermal conductivity from the viewpoint of improving thermal conductivity to a heat sink. Among them, the thermal conductivity of GaN single crystal substrates tends to be lowered by the addition of germanium. On the other hand, in an environment where a semiconductor device is actually used, the temperature may rise due to the operation of the device, but the measurement of thermal conductivity under room temperature conditions has not been focused on the measurement under high temperature conditions so far. Accordingly, the inventors of the present invention studied the change in thermal conductivity of gallium nitride due to temperature, and found that the thermal conductivity of gallium nitride decreases with an increase in temperature even when the temperature is high at room temperature. As described above, when germanium is added at a high concentration to a GaN single crystal substrate in order to reduce the resistivity, the thermal conductivity under the high temperature condition may not be maintained high even if the thermal conductivity under the room temperature condition can be improved. The purpose of the present invention is to provide a technique for reducing the electrical resistivity of a gallium nitride single crystal substrate and maintaining high thermal conductivity even in a high-temperature environment. Solution for solving the problem According to one embodiment of the present invention, there is provided a gallium nitride single crystal substrate, which is a gallium nitride single crystal substrate having a low-index crystal plane (0001) plane closest to a main surface, The gallium nitride single crystal substrate has a resistivity of 1X 10 -2 Ω & cm or less at 200 ℃, The thermal conductivity in the thickness direction at 200 ℃ is 80W/mk or more. According to another aspect of the present invention, there is provided a method for producing a gallium nitride single crystal substrate, comprising: (a) A step of preparing a base substrate formed of a gallium nitride single crystal having a low-index crystal plane (0001) closest to the main surface, and (B) A step of epitaxially growing a gallium nitride single crystal on the main surface of the base substrate, In the above (b), the source gas for forming the gallium nitride single crystal is supplied to the base substrate under an ammonia-containing atmosphere having a growth pressure of 1atm or more and 1.5atm or less, and ammonia is supplied from the periphery of a support member for supporting the base substrate. ADVANTAGEOUS EFFECTS OF INVENTION According to the present invention, the gallium nitride single crystal substrate can maintain high thermal conductivity even in a high-temperature environment while reducing the electrical resistivity. Drawings Fig. 1A is a schematic cross-sectional view showing a part of a method for manufacturing a gallium nitride single crystal substrate according to an embodiment of the present invention. Fig. 1B is a schematic cross-sectional view showing a part of a method for manufacturing a gallium nitride single crystal substrate according to an embodiment of the present invention. Fig. 1C is a schematic cross-sectional view showing a part of a method for manufacturing a gallium nitride single crystal substrate according to an embodiment of the present invention. Fig. 2