Preparation process of high-purity gallium nitride target

Abstract

The application relates to the technical field of gallium nitride target materials, in particular to a preparation process of high-purity gallium nitride target material, which comprises the following steps: step 1, cold pressing forming: obtaining a green body; step 2, primary sintering; step 3, secondary sintering; step 4, cooling and impurity removal: obtaining a gallium nitride slab blank; step 5, slab blank rolling; and step 6, finishing: performing surface processing on the rolled gallium nitride slab blank to a required size and surface roughness. The preparation process of the high-purity gallium nitride target material is characterized in that: firstly, gallium oxide and ammonia gas are subjected to a primary reaction to generate gallium nitride with micropores; then, sodium, gallium and nitrogen gas are added to perform a secondary reaction, so that a dense gallium nitride sintered blank can be finally generated; and after surface impurity removal and rolling, the high-purity gallium nitride target material is obtained. The whole preparation process is convenient and low in energy consumption, and is suitable for popularization and use.

Description

Technical Field

[0001] This invention relates to the field of gallium nitride target technology, and more particularly to a process for preparing high-purity gallium nitride targets. Background Technology

[0002] Gallium nitride (GaN) targets are key materials for preparing high-performance GaN thin films using physical vapor deposition methods such as magnetron sputtering, requiring high purity (≥5N), high density (relative density >99%), and good microstructural integrity. However, GaN is prone to decomposition at ambient pressure and high temperature and has an extremely low self-diffusion coefficient, making it impossible to densify it through melting and casting.

[0003] The current mainstream preparation route is as follows: high-purity GaN powder is sintered under pressure, such as hot pressing, hot isostatic pressing, or spark plasma sintering. These methods require high temperature and pressure to suppress GaN decomposition, resulting in high costs and difficulty in completely eliminating residual micropores and the enrichment of impurities such as oxygen and carbon introduced by the original powder particle boundaries. Therefore, we propose a preparation process for high-purity gallium nitride targets to address these issues. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a process for preparing high-purity gallium nitride targets.

[0005] A process for preparing a high-purity gallium nitride target includes the following steps:

[0006] Step 1, Cold pressing: Gallium oxide powder is loaded into the mold and held under pressure of 200-300MPa for 5-10 minutes to obtain a green blank;

[0007] Step 2, First sintering: Place the green billet into the sintering furnace. First, evacuate the sintering furnace. After evacuation, fill it with ammonia gas and then heat it to 1000-1100℃ at a rate of 5-8℃ / min. Hold the temperature for 2-3 hours.

[0008] Step 3, Secondary sintering: After the sintering furnace is cooled to room temperature, a vacuum is evacuated once, a mixture of gallium and sodium is added, a vacuum is evacuated again, then nitrogen is introduced, and finally the temperature is raised to 750-850℃ at a rate of 5-8℃ / min and held for 8-16 hours to obtain gallium nitride sintered billet.

[0009] Step 4, Cooling and impurity removal: The gallium nitride sintered billet is first washed with anhydrous ethanol, and then washed with dilute hydrochloric acid to obtain a gallium nitride plate.

[0010] Step 5, Slab Rolling: The gallium nitride slab is rolled to achieve a final deformation of 25%-40%;

[0011] Step 6, finishing: After rolling, the gallium nitride slab is surface-finished to the required size and surface roughness to produce high-purity gallium nitride target material.

[0012] Preferably, in step 1, the particle size of the gallium oxide powder is 1-20 μm.

[0013] Preferably, in step 2, the pressure of ammonia gas in the sintering furnace is 0.01-0.1 MPa.

[0014] Preferably, in step 3, the pressure of nitrogen gas inside the sintering furnace is 5-10 MPa.

[0015] Preferably, in step 3, the molar ratio of gallium to sodium in the gallium-sodium mixture is 1:1-3.

[0016] Preferably, in step 3, the total mass ratio of the gallium and sodium mixture to the mass of the green blank is (0.02-0.2):1.

[0017] Preferably, in step 3, the purity of gallium is ≥99.999%.

[0018] Preferably, in step 4, the concentration of the dilute hydrochloric acid is 0.1-0.5 mol / L. After washing with dilute hydrochloric acid, the gallium nitride blank is rinsed with deionized water and finally vacuum dried.

[0019] Preferably, in step 5, the rolled gallium nitride slab is subjected to C-Scan flaw detection.

[0020] The beneficial effects of this invention are as follows: The preparation process of high-purity gallium nitride target proposed in this invention first involves a primary reaction between gallium oxide and ammonia to generate gallium nitride with micropores; then, sodium, gallium, and nitrogen are added for a secondary reaction. Sodium lowers the melting point of gallium, forming a low-temperature gallium-sodium melt, which increases the solubility of nitrogen. Metallic sodium reacts with nitrogen to generate an intermediate compound, sodium nitride. Sodium nitride then undergoes a displacement reaction with gallium to generate gallium nitride and release sodium. The entire growth process uses the gallium nitride generated in the primary reaction as a substrate, ultimately generating a dense gallium nitride sintered billet. After surface impurity removal and rolling, a high-purity gallium nitride target is obtained. The entire preparation process is convenient and energy-efficient, making it suitable for widespread use. Detailed Implementation

[0021] The present invention will be further explained below with reference to specific embodiments.

[0022] Example 1: A process for preparing a high-purity gallium nitride target includes the following steps:

[0023] Step 1, Cold pressing: Gallium oxide powder is loaded into a mold and held under pressure of 200MPa for 5 minutes to obtain a green blank;

[0024] Step 2, First sintering: Place the green billet into the sintering furnace. First, evacuate the sintering furnace. After evacuation, fill it with ammonia gas and then heat it to 1000℃ at a rate of 5℃ / min and hold it for 2 hours.

[0025] Step 3, Secondary sintering: After the sintering furnace is cooled to room temperature, a vacuum is evacuated once, a mixture of gallium and sodium is added, a vacuum is evacuated again, then nitrogen is introduced, and finally the temperature is raised to 750°C at a rate of 5°C / min and held for 8 hours to obtain gallium nitride sintered billet.

[0026] Step 4, Cooling and impurity removal: The gallium nitride sintered billet is first washed with anhydrous ethanol, and then washed with dilute hydrochloric acid to obtain a gallium nitride plate.

[0027] Step 5, Slab Rolling: The gallium nitride slab is rolled to achieve a final deformation of 25%.

[0028] Step 6, finishing: After rolling, the gallium nitride slab is surface-finished to the required size and surface roughness to produce high-purity gallium nitride target material.

[0029] In step 1, the particle size of the gallium oxide powder is 1-20 μm.

[0030] In step 2, the pressure of ammonia gas in the sintering furnace is 0.01 MPa.

[0031] In step 3, the nitrogen pressure inside the sintering furnace is 5 MPa.

[0032] In step 3, the molar ratio of gallium to sodium in the gallium-sodium mixture is 1:1.

[0033] In step 3, the total mass ratio of the gallium and sodium mixture to the mass of the green blank is 0.02:1.

[0034] In step 3, the purity of gallium is ≥99.999%.

[0035] In step 4, the concentration of dilute hydrochloric acid is 0.1 mol / L. After washing with dilute hydrochloric acid, the gallium nitride blank is rinsed with deionized water and finally vacuum dried.

[0036] In step 5, the rolled gallium nitride slab is subjected to C-Scan flaw detection.

[0037] Example 2: A process for preparing a high-purity gallium nitride target includes the following steps:

[0038] Step 1, Cold pressing: Gallium oxide powder is loaded into a mold and held under pressure of 300MPa for 10 minutes to obtain a green blank;

[0039] Step 2, First sintering: The green billet is placed into the sintering furnace. The sintering furnace is first evacuated. After the evacuation is completed, ammonia gas is introduced. Then the temperature is raised to 1100℃ at a rate of 8℃ / min and held for 3 hours.

[0040] Step 3, Secondary sintering: After the sintering furnace is cooled to room temperature, a vacuum is evacuated once, a mixture of gallium and sodium is added, a vacuum is evacuated again, then nitrogen is introduced, and finally the temperature is raised to 850°C at a rate of 8°C / min and held for 16 hours to obtain gallium nitride sintered billet.

[0041] Step 4, Cooling and impurity removal: The gallium nitride sintered billet is first washed with anhydrous ethanol, and then washed with dilute hydrochloric acid to obtain a gallium nitride plate.

[0042] Step 5, Slab Rolling: The gallium nitride slab is rolled to achieve a final deformation of 25%-40%;

[0043] Step 6, finishing: After rolling, the gallium nitride slab is surface-finished to the required size and surface roughness to produce high-purity gallium nitride target material.

[0044] In step 1, the particle size of the gallium oxide powder is 1-20 μm.

[0045] In step 2, the pressure of ammonia gas inside the sintering furnace is 0.1 MPa.

[0046] In step 3, the pressure of nitrogen gas inside the sintering furnace is 10 MPa.

[0047] In step 3, the molar ratio of gallium to sodium in the gallium-sodium mixture is 1:3.

[0048] In step 3, the total mass ratio of the gallium and sodium mixture to the mass of the green blank is 0.2:1.

[0049] In step 3, the purity of gallium is ≥99.999%.

[0050] In step 4, the concentration of dilute hydrochloric acid is 0.5 mol / L. After washing with dilute hydrochloric acid, the gallium nitride blank is rinsed with deionized water and finally vacuum dried.

[0051] In step 5, the rolled gallium nitride slab is subjected to C-Scan flaw detection.

[0052] Example 3: A process for preparing a high-purity gallium nitride target includes the following steps:

[0053] Step 1, Cold pressing: Gallium oxide powder is loaded into a mold and held under pressure of 260MPa for 8 minutes to obtain a green blank;

[0054] Step 2, First sintering: The green billet is placed into the sintering furnace. The sintering furnace is first evacuated. After the evacuation is completed, ammonia gas is introduced. Then the temperature is raised to 1050℃ at a rate of 6℃ / min and held for 2.5h.

[0055] Step 3, Secondary sintering: After the sintering furnace is cooled to room temperature, a vacuum is evacuated once, a mixture of gallium and sodium is added, a vacuum is evacuated again, then nitrogen is introduced, and finally the temperature is raised to 800°C at a rate of 7°C / min and held for 12 hours to obtain gallium nitride sintered billet.

[0056] Step 4, Cooling and impurity removal: The gallium nitride sintered billet is first washed with anhydrous ethanol, and then washed with dilute hydrochloric acid to obtain a gallium nitride plate.

[0057] Step 5, Slab Rolling: The gallium nitride slab is rolled to achieve a final deformation of 32%.

[0058] Step 6, finishing: After rolling, the gallium nitride slab is surface-finished to the required size and surface roughness to produce high-purity gallium nitride target material.

[0059] In step 1, the particle size of the gallium oxide powder is 1-20 μm.

[0060] In step 2, the pressure of ammonia gas in the sintering furnace is 0.05 MPa.

[0061] In step 3, the pressure of nitrogen gas inside the sintering furnace is 7 MPa.

[0062] In step 3, the molar ratio of gallium to sodium in the gallium-sodium mixture is 1:2.

[0063] In step 3, the total mass ratio of the gallium and sodium mixture to the mass of the green blank is 0.08:1.

[0064] In step 3, the purity of gallium is ≥99.999%.

[0065] In step 4, the concentration of dilute hydrochloric acid is 0.3 mol / L. After washing with dilute hydrochloric acid, the gallium nitride blank is rinsed with deionized water and finally vacuum dried.

[0066] In step 5, the rolled gallium nitride slab is subjected to C-Scan flaw detection.

[0067] Example 4: A process for preparing a high-purity gallium nitride target, comprising the following steps:

[0068] Step 1, Cold pressing: Gallium oxide powder is loaded into a mold and held under pressure of 260MPa for 8 minutes to obtain a green blank;

[0069] Step 2, First sintering: The green billet is placed into the sintering furnace. The sintering furnace is first evacuated. After the evacuation is completed, ammonia gas is introduced. Then the temperature is raised to 1050℃ at a rate of 6℃ / min and held for 2.5h.

[0070] Step 3, Secondary sintering: After the sintering furnace is cooled to room temperature, a vacuum is evacuated once, a mixture of gallium and sodium is added, a vacuum is evacuated again, then nitrogen is introduced, and finally the temperature is raised to 800°C at a rate of 7°C / min and held for 12 hours to obtain gallium nitride sintered billet.

[0071] Step 4, Cooling and impurity removal: The gallium nitride sintered billet is first washed with anhydrous ethanol, and then washed with dilute hydrochloric acid to obtain a gallium nitride plate.

[0072] Step 5, Slab Rolling: The gallium nitride slab is rolled to achieve a final deformation of 32%.

[0073] Step 6, finishing: After rolling, the gallium nitride slab is surface-finished to the required size and surface roughness to produce high-purity gallium nitride target material.

[0074] In step 1, the particle size of the gallium oxide powder is 1-20 μm.

[0075] In step 2, the pressure of ammonia gas inside the sintering furnace is 0.1 MPa.

[0076] In step 3, the pressure of nitrogen gas inside the sintering furnace is 10 MPa.

[0077] In step 3, the molar ratio of gallium to sodium in the gallium-sodium mixture is 1:3.

[0078] In step 3, the total mass ratio of the gallium and sodium mixture to the mass of the green blank is 0.2:1.

[0079] In step 3, the purity of gallium is ≥99.999%.

[0080] In step 4, the concentration of dilute hydrochloric acid is 0.5 mol / L. After washing with dilute hydrochloric acid, the gallium nitride blank is rinsed with deionized water and finally vacuum dried.

[0081] In step 5, the rolled gallium nitride slab is subjected to C-Scan flaw detection.

[0082] Example 5: A process for preparing a high-purity gallium nitride target, comprising the following steps:

[0083] Step 1, Cold pressing: Gallium oxide powder is loaded into a mold and held under pressure of 260MPa for 8 minutes to obtain a green blank;

[0084] Step 2, First sintering: The green billet is placed into the sintering furnace. The sintering furnace is first evacuated. After the evacuation is completed, ammonia gas is introduced. Then the temperature is raised to 1050℃ at a rate of 6℃ / min and held for 2.5h.

[0085] Step 3, Secondary sintering: After the sintering furnace is cooled to room temperature, a vacuum is evacuated once, a mixture of gallium and sodium is added, a vacuum is evacuated again, then nitrogen is introduced, and finally the temperature is raised to 800°C at a rate of 7°C / min and held for 12 hours to obtain gallium nitride sintered billet.

[0086] Step 4, Cooling and impurity removal: The gallium nitride sintered billet is first washed with anhydrous ethanol, and then washed with dilute hydrochloric acid to obtain a gallium nitride plate.

[0087] Step 5, Slab Rolling: The gallium nitride slab is rolled to achieve a final deformation of 32%.

[0088] Step 6, finishing: After rolling, the gallium nitride slab is surface-finished to the required size and surface roughness to produce high-purity gallium nitride target material.

[0089] In step 1, the particle size of the gallium oxide powder is 1-20 μm.

[0090] In step 2, the pressure of ammonia gas in the sintering furnace is 0.05 MPa.

[0091] In step 3, the pressure of nitrogen gas inside the sintering furnace is 7 MPa.

[0092] In step 3, the molar ratio of gallium to sodium in the gallium-sodium mixture is 1:2.

[0093] In step 3, the total mass ratio of the gallium and sodium mixture to the mass of the green blank is 0.08:1.

[0094] In step 3, the purity of gallium is ≥99.999%.

[0095] In step 4, the concentration of dilute hydrochloric acid is 0.3 mol / L. After washing with dilute hydrochloric acid, the gallium nitride blank is rinsed with deionized water and finally vacuum dried.

[0096] In step 5, the rolled gallium nitride slab is subjected to C-Scan flaw detection.

[0097] In Comparative Example 1, no secondary sintering was performed compared to Example 3, and the rest of the process was the same as in Example 3.

[0098] In Comparative Example 2, no slab rolling was performed compared to Example 3, and the rest of the process was the same as in Example 3.

[0099] The performance of Examples 1-5 and Comparative Examples 1-2 was tested below. The tests included product purity, density, and average grain size. The test results are shown in Table 1.

[0100] Table 1

[0101]

[0102] In Examples 1-5, the obtained high-purity gallium nitride targets have high purity, good crystal quality, and moderate grain size; in Comparative Example 1, the texture distribution is not uniform enough; in Comparative Example 2, the texture distribution is not uniform enough, but it is better than that of Comparative Example 1.

[0103] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A process for preparing a high-purity gallium nitride target, characterized in that, Includes the following steps: Step 1, Cold pressing: Gallium oxide powder is loaded into the mold and held under pressure of 200-300MPa for 5-10 minutes to obtain a green blank; Step 2, First sintering: Place the green billet into the sintering furnace. First, evacuate the sintering furnace. After evacuation, fill it with ammonia gas and then heat it to 1000-1100℃ at a rate of 5-8℃ / min. Hold the temperature for 2-3 hours. Step 3, Secondary sintering: After the sintering furnace is cooled to room temperature, a vacuum is evacuated once, a mixture of gallium and sodium is added, a vacuum is evacuated again, then nitrogen is introduced, and finally the temperature is raised to 750-850℃ at a rate of 5-8℃ / min and held for 8-16 hours to obtain gallium nitride sintered billet. Step 4, Cooling and impurity removal: The gallium nitride sintered billet is first washed with anhydrous ethanol, and then washed with dilute hydrochloric acid to obtain a gallium nitride plate. Step 5, Slab Rolling: The gallium nitride slab is rolled to achieve a final deformation of 25%-40%; Step 6, finishing: After rolling, the gallium nitride slab is surface-finished to the required size and surface roughness to produce high-purity gallium nitride target material.

2. The preparation process of a high-purity gallium nitride target according to claim 1, characterized in that, In step 1, the particle size of the gallium oxide powder is 1-20 μm.

3. The preparation process of a high-purity gallium nitride target according to claim 1, characterized in that, In step 2, the pressure of ammonia gas in the sintering furnace is 0.01-0.1 MPa.

4. The preparation process of a high-purity gallium nitride target according to claim 1, characterized in that, In step 3, the pressure of nitrogen gas inside the sintering furnace is 5-10 MPa.

5. The preparation process of a high-purity gallium nitride target according to claim 1, characterized in that, In step 3, the molar ratio of gallium to sodium in the gallium-sodium mixture is 1:1-3.

6. The preparation process of a high-purity gallium nitride target according to claim 5, characterized in that, In step 3, the total mass ratio of the gallium and sodium mixture to the mass of the green blank is (0.02-0.2):

1.

7. The preparation process of a high-purity gallium nitride target according to claim 1, characterized in that, In step 3, the purity of gallium is ≥99.999%.

8. The preparation process of a high-purity gallium nitride target according to claim 1, characterized in that, In step 4, the concentration of the dilute hydrochloric acid is 0.1-0.5 mol / L. After washing with dilute hydrochloric acid, the gallium nitride blank is rinsed with deionized water and finally vacuum dried.

9. The preparation process of a high-purity gallium nitride target according to claim 1, characterized in that, In step 5, the rolled gallium nitride slab is subjected to C-Scan flaw detection.

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