Method for preparing nitride semiconductor material

Abstract

The present invention provides a method for preparing a nitride semiconductor material, comprising the following steps: (1) forming a high-absorption layer on one surface of a substrate; (2) depositing a nitride semiconductor material on the high-absorption layer or on the other surface of the substrate opposite to the high-absorption layer by means of microwave heating; the high-absorption layer is formed of a material having a dielectric loss factor of not less than 0.01. By the method of the present invention, uniform heat conduction of the nitride semiconductor material can be achieved. At the same time, the method of the present invention has higher energy utilization efficiency. In the method of the present invention, energy is concentrated and absorbed by the material to be heated, and the cavity of the vacuum deposition equipment will not be heated, which is beneficial to extending the maintenance and use of the equipment.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor materials. Specifically, the present invention relates to a method for preparing nitride semiconductor materials. Background Art

[0002] With the progress of semiconductor production and manufacturing technologies, as well as the progress of science and technology and the development of society, the application fields of semiconductors are becoming more and more extensive, and the requirements for the performance of semiconductors are also getting higher and higher. Semiconductor materials not only have great applications in the optoelectronic field, but also are the cornerstone of the power electronics field. Especially the III-V semiconductor materials.

[0003] During the growth process of semiconductor materials, a high-temperature process must be experienced. Even after the structure growth is completed, a high-temperature process is also required to achieve the final function. The high-temperature process serves purposes such as promoting material growth, activating elements, and releasing stress. Currently, in material growth equipment (such as MOCVD, MBE), the mainly adopted methods are resistance wire heating or infrared heating. The strength of the resistance wire is relatively low in a high-temperature environment. As the temperature rises, the plasticity of the heating wire will increase, and it is prone to deformation at high temperatures, and it is not easy to repair after deformation. Infrared heating reacts too fast and the temperature rises too rapidly.

[0004] The main advantages of microwave heating include: instantaneously applying and withdrawing energy; directly heating the material rather than heat conduction, and the inside and surface of the material are heated simultaneously; selective heating can be performed, which enables the structure being grown to be heated individually instead of heating the entire equipment cavity, making the growth of the material simpler and easier. For example, when growing gallium nitride on sapphire, since the microwave only heats the gallium nitride and does not heat the sapphire, it is possible to more simply control the thermal stress. Moreover, since the entire gallium nitride material can absorb microwave energy, the gallium nitride material can be heated more uniformly. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a new method for preparing nitride semiconductor materials. The new method for preparing nitride semiconductor materials of the present invention adopts a microwave heating method. Through the method of the present invention, uniform heat conduction of the nitride semiconductor materials can be achieved. At the same time, the method of the present invention has a higher energy utilization efficiency.

[0006] The above object of the present invention is achieved by the following technical solutions.

[0007] The present invention provides a method for preparing nitride semiconductor materials, comprising the following steps:

[0008] (1) Form a high-absorption layer on one surface of the substrate;

[0009] (2) On the high-absorption layer or on the other surface of the substrate opposite to the high-absorption layer, a nitride semiconductor material is deposited by means of microwave heating;

[0010] The high-absorption layer is formed of a material with a dielectric loss factor of not less than 0.01.

[0011] Preferably, in the method of the present invention, the substrate is a sapphire, silicon or silicon carbide substrate.

[0012] Preferably, in the method of the present invention, the high-absorption layer is formed of one or more of GaO, ZnO, TiO2 and the compound of formula Al x Ga (1-x) N, where 0 ≤ x ≤ 1.

[0013] Preferably, in the method of the present invention, the high-absorption layer is formed of GaN and / or AlN.

[0014] Preferably, in the method of the present invention, the thickness of the high-absorption layer is 50 nm - 2 μm.

[0015] Preferably, in the method of the present invention, the formation of the high-absorption layer in step (1) is carried out by physical or chemical deposition.

[0016] Preferably, in the method of the present invention, the physical or chemical deposition is carried out by sputtering, evaporation, chemical vapor deposition, atomic layer deposition or molecular beam epitaxial deposition.

[0017] Preferably, in the method of the present invention, the method further includes a step of patterning the high-absorption layer after step (1) and before step (2).

[0018] Preferably, in the method of the present invention, the microwave heating is carried out under the following conditions: controlling the frequency of the microwave heating source in a vacuum deposition chamber to be 2 GHz - 20 GHz.

[0019] Advantages of the present invention:

[0020] (1) The method of the present invention has a wide range of applications: In the present invention, the nitride semiconductor material includes but is not limited to III-V group semiconductor materials and their metal oxide semiconductor materials. For example, by using the method of the present invention, a gallium nitride-based LED structure, a gallium nitride-based HEMT structure or a gallium nitride-based detector structure can be prepared.

[0021] (2) By virtue of the high absorption of microwaves by the high-absorption layer, the method of the present invention can achieve uniform heat conduction of nitride semiconductor materials. At the same time, the method of the present invention has higher energy utilization efficiency. In the method of the present invention, the energy is concentratedly absorbed by the material to be heated, and the cavity of the vacuum deposition equipment will not be heated, which is beneficial to extending the maintenance and use of the equipment. Description of the Drawings

[0022] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings, wherein:

[0023] Figure 1 is a flowchart of the method of Embodiment 1 of the present invention;

[0024] Figure 2 is a flowchart of the method of Embodiment 2 of the present invention;

[0025] Figure 3 is a flowchart of the method of Embodiment 3 of the present invention;

[0026] Figure 4 is a flowchart of the method of Embodiment 4 of the present invention;

[0027] Figure 5 is a schematic cross-sectional view of the structure of the nitride semiconductor material prepared on the high-absorption layer by microwave heating in Embodiment 1 of the present invention;

[0028] Figure 6 is a schematic cross-sectional view of the structure of the nitride semiconductor material prepared on the patterned high-absorption layer by microwave heating in Embodiment 2 of the present invention;

[0029] Figure 7 is a schematic cross-sectional view of the structure of the nitride semiconductor material prepared on the other surface of the substrate opposite to the high-absorption layer by microwave heating in Embodiment 3 of the present invention;

[0030] Figure 8 is a schematic cross-sectional view of the structure of the nitride semiconductor material prepared on the high-absorption layer by microwave heating in Embodiment 4 of the present invention;

[0031] Figure 9 is an SEM scan of the cross-section of the material prepared in Embodiment 4 of the present invention;

[0032] Figure 10 is an AFM scan of the material prepared in Embodiment 4 of the present invention;

[0033] Figure 11 is the current-voltage characteristic of the LED device prepared from the structure grown in Embodiment 4 of the present invention;

[0034] Among them, the reference numerals are as follows:

[0035] 1 Substrate

[0036] 2 High absorption layer

[0037] 3 Nitride semiconductor material. Detailed implementation manners

[0038] The present invention will be further described in detail below in conjunction with the specific implementation manners. The examples given are only for clarifying the present invention, rather than limiting the scope of the present invention.

[0039] Example 1

[0040] This embodiment relates to a method for preparing nitride semiconductor materials by microwave heating. The specific process is as Figure 1 shown, and it includes the following steps:

[0041] (1) Provide a 2-inch sapphire substrate required for growth;

[0042] (2) Grow a layer of aluminum nitride (AlN) on one surface of the substrate;

[0043] The AlN material is prepared by sputtering. The substrate temperature is 200 °C, the flow ratio of N2 / Ar is 1:2, the working pressure is 0.1 Pa, and the thickness of the grown AlN material is 100 nm;

[0044] (3) On the AlN material, in a MOCVD chamber with a vacuum of 400 mbar, use microwave heating to prepare nitride semiconductor materials to form GaN-based LEDs;

[0045] During the growth of the nitride semiconductor material, heat the AlN layer with no less than one microwave emitter. The frequency of the microwave source is 2.4 GHz, and the AlN is heated to 1150 °C to grow the nitride semiconductor material. With the high absorption of microwaves by AlN, on the one hand, it ensures uniform heat conduction of the nitride semiconductor material, overcoming the problem of low efficiency of non-contact heating; on the other hand, because the area of AlN corresponds to that of the nitride semiconductor material, the energy utilization efficiency is improved. First, grow a GaN buffer layer with a thickness of about 600 nm on the AlN surface; then heat the substrate to 1050 °C by microwave; then deposit 4 um of N-type GaN, then cool the substrate to 800 °C, and then deposit a GaN / InGaN multiple quantum well structure; next, raise the temperature to 900 °C, and grow P-type Mg-doped GaN on the surface of the quantum well to complete the growth of the structure. Figure 5 This is a schematic cross-sectional view of the structure of the nitride semiconductor material prepared by microwave heating in this example on the high absorption layer.

[0046] Example 2

[0047] This embodiment relates to a method for preparing semiconductor materials by microwave heating. The specific process is as Figure 2 shown and includes the following steps:

[0048] (1) Provide a 2-inch silicon substrate required for growth;

[0049] (2) Grow a layer of aluminum nitride (AlN) material on one surface of the substrate;

[0050] The AlN material is prepared by sputtering. The substrate temperature is 200 °C, the flow ratio of N2 / Ar is 1:2, the working pressure is 0.1 Pa, and the thickness of the grown AlN material is 1.5 μm;

[0051] (3) Pattern the aluminum nitride material;

[0052] Use methods such as ultraviolet exposure or nanoimprinting to prepare a photoresist pattern with a periodic structure, and then transfer the pattern to AlN by etching to prepare a pattern with a depth of 100 nm;

[0053] (4) On the AlN material, in an MOCVD chamber with a vacuum of 400 mbar, use microwave heating to prepare a nitride semiconductor material to form a GaN-based LED;

[0054] During the growth of the nitride semiconductor material, heat the aluminum nitride layer with at least one microwave emission source. The microwave power is 6.5 GHz, and the nitride semiconductor material is grown by specifically heating AlN to 1150 °C. With the high absorption of microwaves by AlN, on the one hand, it ensures uniform heat conduction of the nitride semiconductor material and overcomes the problem of low efficiency of non-contact heating; on the other hand, because the area of aluminum nitride corresponds to that of the nitride semiconductor material, the energy utilization efficiency is improved. First, grow a GaN buffer layer with a thickness of about 500 nm on the AlN surface; then heat the substrate to 1050 °C by microwave; then deposit 4 μm of N-type GaN, then cool the substrate to 800 °C, and then deposit a GaN / InGaN multi-quantum well structure; next, raise the temperature to 900 °C and grow P-type Mg-doped GaN on the surface of the quantum well to complete the growth of the structure. Figure 6 This is a schematic cross-sectional view of the structure of the nitride semiconductor material prepared by microwave heating on the patterned high-absorption layer in this example.

[0055] Example 3

[0056] This embodiment relates to a method for preparing semiconductor materials by microwave heating. The specific process is as Figure 3 shown and includes the following steps:

[0057] (1) Provide a 2-inch sapphire substrate required for growth;

[0058] (2) Grow a layer of titanium dioxide (TiO2) on one surface of the substrate;

[0059] The TiO2 material is prepared by sputtering. The substrate temperature is 200 °C, the flow ratio of N2 / Ar is 1:2, the working pressure is 0.1 Pa, and the thickness of the grown TiO2 material is 100 nm;

[0060] (3) On the other surface of the substrate opposite to the titanium dioxide, in a MOCVD chamber with a vacuum of 400 mbar, use microwave heating to prepare a nitride semiconductor material to form a GaN-based LED;

[0061] During the growth of the nitride semiconductor material, heat the TiO2 layer with at least one microwave emitter. The microwave frequency is 16 GHz, and the nitride semiconductor material is grown by specifically heating the TiO2 to 1150 °C. With the high absorption of microwaves by TiO2, on the one hand, it ensures uniform heat conduction to the nitride semiconductor material; on the other hand, because the area of TiO2 corresponds to that of the nitride semiconductor material, the energy utilization efficiency is improved. First, grow a GaN buffer layer with a thickness of about 700 nm on the surface of the substrate opposite to the TiO2; then heat the substrate to 1050 °C by microwave; then deposit 4 um of N-type GaN, then cool the substrate to 800 °C, and then deposit a GaN / InGaN multiple quantum well structure; next, raise the temperature to 900 °C and grow P-type Mg-doped GaN on the surface of the quantum well to complete the growth of the structure. Figure 7 It is a schematic cross-sectional view of the structure of the nitride semiconductor material prepared by microwave heating on the other surface of the substrate opposite to the high absorption layer in this embodiment.

[0062] Example 4

[0063] This embodiment relates to a method for preparing a semiconductor material by microwave heating. The specific process is as Figure 4 shown, and it includes the following steps:

[0064] (1) Provide a 2-inch sapphire substrate required for growth;

[0065] (2) Grow a layer of GaN material on one surface of the substrate;

[0066] Use resistance heating to grow the GaN material. By using a resistance wire heating method, the substrate is heated to 1150 °C, and the growth of the GaN buffer layer is carried out in a MOCVD chamber with a vacuum of 400 mbar. The thickness of the grown GaN material is 200 nm;

[0067] (3) On the GaN material, in a MOCVD chamber with a vacuum degree of 400 mbar, microwave heating is used to prepare a nitride semiconductor material to form a GaN-based LED;

[0068] During the growth of the nitride semiconductor material, the GaN buffer layer is heated by no less than one microwave emitter. The microwave frequency is 2.56 GHz, and the nitride semiconductor material is grown by heating GaN to a suitable temperature in a specific manner. By virtue of the high absorption of GaN to microwaves, on the one hand, it ensures uniform heat conduction to the nitride semiconductor material, overcoming the problem of low efficiency of non-contact heating; on the other hand, because the area of aluminum nitride corresponds to that of the nitride semiconductor material, the energy utilization efficiency is improved. The substrate is heated to 1050 °C by microwaves; then 4 μm of N-type GaN is deposited, and then the substrate is cooled to 800 °C, and then a GaN / InGaN multi-quantum well structure is deposited; next, the temperature is raised to 900 °C, and P-type Mg-doped GaN is grown on the surface of the quantum well to complete the growth of the structure. Figure 8 It is a schematic cross-sectional view of the nitride semiconductor material prepared on the high-absorption layer by microwave heating in this embodiment. Figure 9 It is an SEM scan image of the cross-section of the material prepared in this embodiment. Figure 9 It shows a clear layered structure and a clear interface between the nitride semiconductor material and the sapphire substrate. Figure 10 It is an AFM scan image of the material prepared in this embodiment. Figure 10 It shows that the morphology of the surface of the prepared material conforms to that of a normal nitride material. Figure 11 It is the current-voltage characteristic of the LED device prepared by using the structure grown in this embodiment. It can be seen that the LED device prepared by the present invention has normal performance.

Claims

1. A method for preparing a nitride semiconductor material, comprising the following steps: (1) forming a high absorption layer on one surface of a substrate; (2) depositing a nitride semiconductor material on the high absorption layer or on the other surface of the substrate opposite to the high absorption layer by means of microwave heating; The high absorption layer is formed of a material having a dielectric loss factor of not less than 0.01; The high absorption layer is formed of GaN and / or TiO2; The thickness of the high absorption layer is 50 nm - 2 μm.

2. The method according to claim 1, wherein, The substrate is a sapphire, silicon or silicon carbide substrate.

3. The method according to claim 1, wherein The formation of the high absorption layer in step (1) is carried out by physical or chemical deposition.

4. The method according to claim 3, wherein The physical or chemical deposition is carried out by sputtering, evaporation, chemical vapor deposition, atomic layer deposition or molecular beam epitaxial deposition.

5. The method according to claim 1, wherein, The method further includes a step of patterning the high absorption layer after step (1) and before step (2).

6. The method according to claim 1, wherein, The microwave heating is carried out under the following conditions: controlling the frequency of the microwave heating source in a vacuum deposition chamber to be 2 GHz - 20 GHz.

Images