JP-7855059-B2 - Group III element nitride substrate and method for manufacturing a Group III element nitride substrate

JP7855059B2JP 7855059 B2JP7855059 B2JP 7855059B2JP-7855059-B2

Inventors

今津研太
磯田佳範
今井克宏

Assignees

ＮＧＫ株式会社

Dates

Publication Date: 20260507
Application Date: 20221213
Priority Date: 20220328

Claims (5)

A group III element nitride substrate having a first principal surface and a second principal surface facing each other, The inclination angle of the first main surface with respect to the (0001) surface is 10° or less. The inclination angle of the second main surface with respect to the (000-1) surface is 10° or less. The thermal conductivity of the group III element nitride in the a-axis direction at a predetermined location within the substrate surface is 2% or more greater than the thermal conductivity of the group III element nitride in the m-axis direction. Group III element nitride substrate.
The difference between the average value of the thermal conductivity in the a-axis direction and the average value of the thermal conductivity in the m-axis direction at multiple locations within the plane of the substrate is 2% or more, according to claim 1 : Here, the difference between the average value of the thermal conductivity in the a-axis direction and the average value of the thermal conductivity in the m-axis direction is calculated using the formula: (average value of thermal conductivity in the a-axis direction - average value of thermal conductivity in the m-axis direction) / average value of thermal conductivity in the a-axis direction.
A group III element nitride substrate according to claim 1 or 2, having a disc shape and a diameter of 75 mm or more.
A group III element nitride substrate according to claim 1 or 2, which is a self-supporting substrate of group III element nitride crystals.
A method for manufacturing a group III element nitride substrate, A seed crystal substrate is prepared, having a base substrate with an upper and lower surface facing each other, and a seed crystal film formed on the upper surface of the base substrate. Growing a group III element nitride crystal on the seed crystal film of the seed crystal substrate by flux method, and This includes separating the group III element nitride crystals from the substrate, The crystal growth by the flux method is carried out such that the flow of the raw material solution in the first direction within the plane of the seed crystal substrate is faster than the flow of the raw material solution in the second direction within the plane of the seed crystal substrate . The aforementioned substrate is a sapphire substrate, The first direction is perpendicular to the m-plane of the substrate. The group III element nitride substrate has a first main surface and a second main surface that face each other. The inclination angle of the first main surface with respect to the (0001) surface is 10° or less. The inclination angle of the second main surface with respect to the (000-1) surface is 10° or less. In a predetermined location within the surface of the group III element nitride substrate, the thermal conductivity of the group III element nitride in the a-axis direction is 2% or more greater than the thermal conductivity of the group III element nitride in the m-axis direction. A method for manufacturing a group III element nitride substrate.

Description

This invention relates to a group III element nitride substrate and a method for manufacturing a group III element nitride substrate. Group III element nitride substrates are used as substrates for various devices such as light-emitting diodes, semiconductor lasers, and power ICs. The above-mentioned Group III element nitride substrate can be obtained, for example, by epitaxially growing Group III element nitride crystals on a substrate, as described in Patent Document 1. Japanese Patent Publication No. 2010-168226 This is a schematic cross-sectional view showing the general structure of a group III element nitride substrate according to one embodiment of the present invention.Figure 1A is a plan view of a group III element nitride substrate.This is a diagram illustrating the measurement points for thermal conductivity.This figure shows the manufacturing process of a group III element nitride substrate according to one embodiment.This figure follows Figure 3A.This figure follows Figure 3B.This is a top view of the substrate placed inside the crucible in the first embodiment.This is a top view of the substrate placed inside the crucible in the second embodiment.This is a schematic cross-sectional view showing the general configuration of an element substrate according to one embodiment of the present invention. The embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. Furthermore, in order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc., of each part compared to the embodiments, but these are merely examples and do not limit the interpretation of the present invention. A. Group III Element Nitride Substrate Figure 1A is a schematic cross-sectional view showing the general configuration of a Group III element nitride substrate according to one embodiment of the present invention, and Figure 1B is a plan view of the Group III element nitride substrate shown in Figure 1A. The Group III element nitride substrate 10 is plate-shaped and has a first main surface 11 and a second main surface 12 facing each other, which are connected via a side surface 13. In the illustrated example, the Group III element nitride substrate is disc-shaped (wafer), but it is not limited to this and can be any suitable shape. The size of the Group III element nitride substrate can be appropriately set according to the purpose. The diameter of the disc-shaped Group III element nitride substrate is, for example, 50 mm or more and 300 mm or less, preferably 75 mm or more, and more preferably 100 mm or more. A larger Group III element nitride substrate (for example, with a diameter of 75 mm or more) can improve the productivity of larger devices, for example. The thickness of the Group III element nitride substrate is, for example, 250 μm or more and 800 μm or less, preferably 300 μm or more and 750 μm or less, and more preferably 350 μm or more and 725 μm or less. Group III element nitride substrates are composed of Group III element nitride crystals. Examples of Group III elements used to make up Group III element nitrides include aluminum (Al), gallium (Ga), and indium (In). These can be used individually or in combination of two or more. Specific examples of Group III element nitrides include aluminum nitride (Al x N), gallium nitride (Ga y N), indium nitride (In z N), aluminum gallium nitride (Al x Ga y N), gallium gallium nitride (Ga y In z N), aluminum gallium nitride (Al x In z N), and aluminum gallium indium nitride (Al x Ga y In z N). In the chemical formulas in parentheses, typically x + y + z = 1. The above-mentioned Group III element nitrides may contain dopants. Examples of dopants include p-type dopants such as beryllium (Be), magnesium (Mg), strontium (Sr), cadmium (Cd), iron (Fe), manganese (Mn), and zinc (Zn), and n-type dopants such as silicon (Si), germanium (Ge), tin (Sn), and oxygen (O). These can be used individually or in combination of two or more. In the above-described Group III element nitride crystal, typically, the <0001> direction is the c-axis direction, the <1-100> direction is the m-axis direction, and the <11-20> direction is the a-axis direction. Furthermore, the crystal plane perpendicular to the c-axis is the c-plane, the crystal plane perpendicular to the m-axis is the m-plane, and the crystal plane perpendicular to the a-axis is the a-plane. In this embodiment, the thickness direction of the Group III element nitride substrate 10 is parallel or substantially parallel to the c-axis, the first main surface 11 is the Group III element polarity plane on the (0001) plane side, and the second main surface 12 is the nitrogen polarity plane on the (000-1) side. Typically, the first main surface 11 may be parallel to the (0001) plane, or it may be inclined with respect to the (0001) plane. The inclination angle of the first main surface 11 with respect to