Silicon target material, preparation method thereof and optical device

Abstract

The present application relates to the technical field of target material preparation, and provides a silicon target material, a preparation method thereof, and an optical device. The preparation method comprises: using gaseous borane to perform boron diffusion treatment on a first silicon powder to obtain a silicon composite powder containing boron and hydrogen; ball milling and mixing the silicon composite powder containing boron and hydrogen with a second silicon powder to obtain a mixed powder; thermally spraying the mixed powder onto a back tube, and then machining to obtain a silicon target material. The preparation method of the silicon target material provided in the present application performs boron diffusion treatment on the first silicon powder, so that the gaseous borane is cracked into boron atoms and hydrogen atoms and diffuses into the silicon powder through the grain boundary to form a silicon composite powder containing boron and hydrogen, which is used as a master alloy with a high boron content, so that boron and silicon have the same deposition rate, thereby accurately controlling the boron content of the target material, and at the same time, hydrogen is removed from the silicon composite powder during the thermal spraying process to release hydrogen to create a reducing environment, so that it can be sprayed under normal pressure and atmospheric atmosphere, and can prevent silicon oxidation, and reduce the oxygen content and resistivity of the silicon target material.

Description

Technical Field

[0001] The present application belongs to the technical field of target material preparation, and in particular, relates to a silicon target material, a preparation method thereof, and an optical device. Background Art

[0002] Silicon dioxide film has excellent optical properties, dielectric insulation, wear resistance and strong corrosion resistance. It has broad application prospects in the fields of optics and microelectronics. It is a functional material that has attracted widespread attention internationally. At present, the preparation methods of silicon dioxide film include chemical vapor deposition (CVD) and physical vapor deposition (PVD) and other methods. Among them, the CVD method is to chemically react silicon source and oxygen source at high temperature to generate silicon dioxide gas, and then react on the surface of the substrate to generate silicon dioxide film. However, it has defects such as high toxicity of the silicon source used, environmental pollution of reaction exhaust gas, and high deposition temperature. In contrast, magnetron sputtering in the PVD method uses silicon target as raw material, does not require precursors, is green and environmentally friendly, and has mature industrial production and good film quality. It is expected to become the mainstream method for preparing silicon dioxide film.

[0003] However, pure silicon target materials have poor electrical and thermal conductivity, and the heat generated during the sputtering process is difficult to transfer and diffuse quickly, which affects the service life of the target material and the stability of the coating. In addition, the sputtering power that can be tolerated is low, resulting in low coating efficiency. Therefore, it is necessary to dope the silicon target material to improve its electrical and thermal conductivity, improve the coating efficiency and stability, and improve the film quality.

[0004] The method commonly used to prepare boron-doped silicon target materials includes: melting silicon powder and boron powder at high temperature to form silicon-boron blocks, then crushing to obtain silicon-boron smelting powder, and then plasma spraying the silicon-boron smelting powder to obtain silicon target materials; or ball-milling silicon powder and boron powder and mixing them, spray granulating to obtain silicon-boron granulated powder, and then plasma spraying the silicon-boron granulated powder to obtain silicon target materials. However, during the thermal spraying process, silicon-boron smelting powder or silicon-boron granulated powder is easily oxidized, resulting in high oxygen content and resistivity of the silicon target material. In addition, high-temperature smelting requires the purchase of additional smelting equipment, which is costly. In the granulated powder of spray granulation, silicon and boron are only physically combined, and it is impossible to ensure that silicon and boron are deposited together, resulting in a low boron deposition rate, so the boron content in the silicon target material cannot be accurately controlled. Summary of the invention

[0005] The purpose of the present application is to provide a silicon target material and a preparation method thereof and an optical device, aiming to solve the problem of high oxygen content and resistivity in existing silicon target materials.

[0006] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0007] In a first aspect, the present application provides a method for preparing a silicon target, comprising the following steps:

[0008] Performing boron diffusion treatment on the first silicon powder using gaseous borane to obtain silicon composite powder containing boron and hydrogen;

[0009] The silicon composite powder containing boron and hydrogen and the second silicon powder are mixed by ball milling to obtain a mixed powder;

[0010] The mixed powder is thermally sprayed onto a backing tube, and then machined to obtain a silicon target.

[0011] In an embodiment, the step of using gaseous borane to perform boron diffusion treatment on the first silicon powder includes: placing the first silicon powder in a vacuum tube furnace, evacuating to 0.1~1.0Pa, introducing a mixed gas of reducing gas and gaseous borane, and performing boron diffusion treatment for 0.5~1h under the conditions of pressure of 10~50kPa and temperature of 800~900℃.

[0012] In an embodiment, the volume ratio of the reducing gas to the gaseous borane is (96-99) / (1-4).

[0013] In an embodiment, the flow rate of the mixed gas is 1-5 mL / min.

[0014] In an embodiment, the gaseous borane is selected from diborane or tetraborane.

[0015] In an embodiment, the reducing gas is selected from hydrogen.

[0016] In an embodiment, the particle size of the first silicon powder is ≤300 μm.

[0017] In an embodiment, the boron content in the silicon composite powder containing boron and hydrogen is 1-3.5 wt %.

[0018] In an embodiment, the particle size of the second silicon powder is ≤300 μm.

[0019] In an embodiment, the particle size of the mixed powder is 100-250 μm.

[0020] In an embodiment, the boron content in the mixed powder is 50-300 ppm.

[0021] In an embodiment, the step of thermally spraying the mixed powder onto the back tube comprises: using atmospheric plasma spraying equipment to spray the mixed powder onto the back tube under normal pressure and atmospheric atmosphere.

[0022] In an embodiment, the atmospheric plasma spraying equipment includes a spray gun, the distance between the spray gun and the central axis of the back tube is 95~115mm, the moving speed of the spray gun is 30~80mm / s, the rotation speed of the back tube is 200~300r / mim, and the powder feeding amount is 100~200g / min.

[0023] In a second aspect, the present application provides a silicon target material, including a silicon target material produced by the method for preparing the silicon target material provided in the present application.

[0024] In an embodiment, the boron content in the silicon target material is 50-300 ppm, the resistivity is 0.01-0.5 Ω·cm, and the thermal conductivity is 200-300 W / (m·K).

[0025] In a third aspect, the present application provides an optical device, comprising a silicon dioxide film layer, wherein the silicon dioxide film layer is obtained by sputtering and coating the silicon target material provided by the present application.

[0026] Compared with the prior art, this application has the following beneficial effects:

[0027] (1) The first silicon powder is subjected to boron diffusion treatment by using gaseous borane to decompose the gaseous borane into boron atoms and hydrogen atoms, and the boron atoms and hydrogen atoms are diffused into the silicon powder by grain boundary diffusion to form a silicon composite powder containing boron and hydrogen. As a master alloy with a high boron content, the boron content of the silicon target can be adjusted by adding the second silicon powder, so that a silicon target with a certain boron content can be customized according to application requirements, and the boron and silicon can be deposited together to ensure that the boron and silicon have the same deposition rate, thereby being able to accurately control the boron content of the silicon target.

[0028] (2) During the thermal spraying process, hydrogen will be released from silicon composite powder to create a reducing environment, which can prevent silicon oxidation. Therefore, it can be sprayed under normal pressure and atmospheric atmosphere, which helps to reduce production costs and at the same time reduce the oxygen content and resistivity of the silicon target. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 It is a process flow chart of the method for preparing a silicon target material provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0032] The first aspect of the present application provides a method for preparing a silicon target material, such as Figure 1As shown, the following steps are included:

[0033] S01: using gaseous borane to perform boron diffusion treatment on the first silicon powder to obtain silicon composite powder containing boron and hydrogen;

[0034] S02: ball-milling the silicon composite powder containing boron and hydrogen and the second silicon powder to obtain a mixed powder;

[0035] S03: thermally spray the mixed powder onto the backing tube, and then machine it to obtain a silicon target.

[0036] The method for preparing a silicon target provided in an embodiment of the present application uses gaseous borane to perform boron diffusion treatment on a first silicon powder, so that the gaseous borane is cracked into boron atoms and hydrogen atoms, and the boron atoms and hydrogen atoms are diffused into the silicon powder by grain boundary diffusion to form a silicon composite powder containing boron and hydrogen. As a master alloy with a high boron content, the boron content of the silicon target can be adjusted by adding a second silicon powder, so that a silicon target with a certain boron content can be customized according to application requirements, and boron and silicon can be deposited together to ensure that boron and silicon have the same deposition rate, so that the boron content of the silicon target can be accurately controlled. In addition, hydrogen removal will occur during the thermal spraying process of the silicon composite powder to release hydrogen to create a reducing environment, which can prevent silicon oxidation, so it can be sprayed under normal pressure and atmospheric atmosphere, which helps to reduce production costs and reduce the oxygen content and resistivity of the silicon target.

[0037] In the above step S01, in the embodiment, the step of using gaseous borane to perform boron diffusion treatment on the first silicon powder includes: placing the first silicon powder in a vacuum tube furnace, evacuating to 0.1~1.0Pa, introducing a mixed gas of reducing gas and gaseous borane, and performing boron diffusion treatment for 0.5~1h under the conditions of pressure of 10~50kPa and temperature of 800~900℃. The boron diffusion treatment conditions of this embodiment are conducive to the decomposition of gaseous borane into boron atoms and hydrogen atoms, and promote the diffusion of boron atoms and hydrogen atoms into the silicon powder to form a silicon composite powder containing boron and hydrogen.

[0038] In the embodiment, the volume ratio of the reducing gas to the gaseous borane is (96-99) / (1-4). This ratio range is beneficial for protecting the gaseous borane from oxidation and for decomposing the gaseous borane.

[0039] In the embodiment, the flow rate of the mixed gas is 1-5 mL / min.

[0040] In an embodiment, the particle size of the first silicon powder is ≤300 μm, preferably 200-300 μm. This particle size range facilitates the diffusion of boron atoms and hydrogen atoms into the silicon powder to form a silicon composite powder with uniform boron distribution, thereby facilitating subsequent spraying to form a silicon target material uniformly doped with boron.

[0041] In the embodiment, the boron content in the silicon composite powder containing boron and hydrogen is 1-3.5 wt %. This boron content range is conducive to the diffusion of boron into the silicon powder and prevents boron from precipitating after cooling to affect the boron deposition rate.

[0042] In the above step S02, in the embodiment, the particle size of the second silicon powder is ≤300 μm, preferably 200-300 μm. This particle size range is conducive to grinding and mixing with the silicon composite powder to form a mixed powder.

[0043] In the embodiment, the particle size of the mixed powder is 100-250 μm. This particle size range can ensure that the mixed powder has good fluidity, which is beneficial to improving the spraying efficiency and the target material quality.

[0044] In the embodiment, the boron content in the mixed powder is 50-300 ppm. This boron content range can ensure that the silicon target material has excellent electrical and thermal conductivity, and can also ensure that the silicon target material coating has excellent optical transmittance.

[0045] In an embodiment, the gaseous borane is selected from diborane or tetraborane.

[0046] In an embodiment, the reducing gas is selected from hydrogen.

[0047] In the embodiment of the present application, the first silicon powder and the second silicon powder may be silicon powders with the same particle size and purity. The first and the second are only for the convenience of expression, used to distinguish the silicon powders added successively.

[0048] In an embodiment, the first silicon powder and the second silicon powder satisfy the requirements that the oxygen content is lower than 500 ppm and the metal impurity content is lower than 100 ppm.

[0049] In the above step S03, in the embodiment, the step of thermally spraying the mixed powder onto the back tube includes: using atmospheric plasma spraying equipment, spraying the mixed powder onto the back tube under normal pressure and atmospheric atmosphere. Normal pressure refers to the air pressure under standard atmospheric conditions.

[0050] In an embodiment, the atmospheric plasma spraying equipment includes a spray gun, and the distance from the spray gun to the central axis of the back tube is 95~115mm. If the distance between the spray gun and the central axis of the back tube is too long, the speed of the particles will be reduced, the kinetic energy will be reduced, and the bonding strength between the coatings and between the coatings and the back tube will be reduced, which will ultimately affect the density and strength of the silicon target obtained by spraying; if the distance between the spray gun and the central axis of the back tube is too short, the speed of the particles will be too high, which will easily cause powder splashing and reduce the deposition rate of the sprayed powder. Therefore, within the spray gun distance range of this embodiment, the mixed powder has a higher deposition rate, and the silicon target has a higher density and stronger mechanical strength.

[0051] The moving speed of the spray gun is 30~80mm / s. Within this moving speed range, the mixed powder can be sprayed on the back tube more evenly, and the coating will not be too thick in some areas, which will affect the bonding strength between the coatings and between the coatings and the back tube.

[0052] The rotation speed of the back tube is 200~300r / mim. Within this rotation speed range, the mixed powder can be sprayed on the back tube more evenly, and the coating will not be too thick in some areas, which will affect the bonding strength between the coatings and between the coatings and the back tube.

[0053] The powder feeding amount is 100~200g / min. This powder feeding amount range can ensure a higher spraying efficiency, and is also conducive to evenly spraying the mixed powder onto the back tube to form a uniform and dense silicon target.

[0054] In an embodiment, machining includes: sandblasting and arc priming of the back tube surface respectively, and spraying can make the surface clean and have a certain roughness; wherein, the sand can be selected from white corundum or brown corundum, and the self-fluxing alloy can be selected from copper-aluminum alloy or nickel-aluminum alloy.

[0055] A second aspect of an embodiment of the present application provides a silicon target material, including a silicon target material prepared by the method for preparing a silicon target material provided in an embodiment of the present application.

[0056] The silicon target material provided in the embodiment of the present application is prepared by the method for preparing the silicon target material provided in the embodiment of the present application, so the silicon target material provided in the embodiment of the present application has the advantages of low oxygen content and low resistivity.

[0057] In the embodiment, the boron content in the silicon target is 50~300ppm, the resistivity is 0.01~0.5Ω·cm, and the thermal conductivity is 200~300W / (m·K). Therefore, the silicon target in this embodiment achieves significant improvement in electrical and thermal conductivity by doping with trace amounts of boron, and the silicon target coating also has excellent optical transmittance.

[0058] A third aspect of an embodiment of the present application provides an optical device, comprising a silicon dioxide film layer, wherein the silicon dioxide film layer is obtained by sputtering and coating the silicon target material provided by an embodiment of the present application.

[0059] The optical device provided in the embodiment of the present application has excellent optical properties, wear resistance and corrosion resistance, and can improve the comprehensive performance of the optical element, because the silicon dioxide film layer contained therein is obtained by sputtering and coating the silicon target material provided in the present application.

[0060] The following describes the invention in conjunction with specific embodiments.

[0061] Example 1

[0062] This embodiment provides a method for preparing a silicon target material, comprising the following steps:

[0063] S11: Place an appropriate amount of silicon powder (D50=250μm, oxygen content less than 500ppm, metal impurity content less than 100ppm) in a vacuum tube furnace, evacuate to 0.5Pa, introduce a mixed gas of hydrogen and diborane at a flow rate of 3mL / min, adjust the pressure in the furnace to 30kPa, heat to 850℃, and perform boron diffusion treatment for 0.5h to obtain silicon composite powder containing boron and hydrogen; wherein the volume ratio of hydrogen to diborane is 98 / 2;

[0064] The boron content in the silicon composite powder was tested to be 2.1wt%;

[0065] S12: Weigh appropriate amounts of silicon composite powder containing boron and hydrogen and silicon powder (D50=250μm, oxygen content less than 500ppm, metal impurity content less than 100ppm), dry grind and mix them evenly to obtain mixed powder (D50=153μm); wherein the boron content in the mixed powder is 152ppm;

[0066] S13: Install the processed back tube on the frame of the atmospheric plasma spraying equipment. The frame drives the back tube to rotate and move axially. The spray gun is installed 105mm above the central axis of the back tube. The moving speed of the spray gun is set to 50mm / s, the rotation speed of the back tube is 250r / min, the powder feeding amount is 150g / min, and water is passed into the back tube to make the temperature of the back tube surface 80℃. Under normal pressure and atmospheric atmosphere conditions, the mixed powder is sprayed onto the back tube for 2h to obtain a silicon target.

[0067] Example 2

[0068] This embodiment provides a method for preparing a silicon target material, comprising the following steps:

[0069] S21: Place an appropriate amount of silicon powder (D50=250μm, oxygen content less than 500ppm, metal impurity content less than 100ppm) in a vacuum tube furnace, evacuate to 0.5Pa, introduce a mixed gas of hydrogen and diborane at a flow rate of 1mL / min, adjust the pressure in the furnace to 10kPa, heat to 800℃, and perform boron diffusion treatment for 0.5h to obtain silicon composite powder containing boron and hydrogen; wherein the volume ratio of hydrogen to diborane is 99 / 1;

[0070] The boron content in the silicon composite powder was tested to be 1.2wt%;

[0071] S22: Weigh silicon composite powder containing boron and hydrogen and silicon powder (D50=250μm, oxygen content less than 500ppm, metal impurity content less than 100ppm), dry grind and mix them evenly to obtain mixed powder (D50=155μm); wherein the boron content in the mixed powder is 58ppm;

[0072] S23: Install the processed back tube on the frame of the atmospheric plasma spraying equipment. The frame drives the back tube to rotate and move axially. The spray gun is installed 105mm above the central axis of the back tube. The moving speed of the spray gun is set to 50mm / s, the rotation speed of the back tube is 250r / min, the powder feeding amount is 150g / min, and water is passed into the back tube to make the temperature of the back tube surface 80℃. Under normal pressure and atmospheric atmosphere conditions, the mixed powder is sprayed onto the back tube for 2h to obtain a silicon target.

[0073] Example 3

[0074] This embodiment provides a method for preparing a silicon target material, comprising the following steps:

[0075] S31: Place an appropriate amount of silicon powder (D50=250μm, oxygen content less than 500ppm, metal impurity content less than 100ppm) in a vacuum tube furnace, evacuate to 0.5Pa, introduce a mixed gas of hydrogen and diborane at a flow rate of 5mL / min, adjust the pressure in the furnace to 50kPa, heat to 900℃, and perform boron diffusion treatment for 1h to obtain silicon composite powder containing boron and hydrogen; wherein the volume ratio of hydrogen to diborane is 96 / 4;

[0076] The boron content in the silicon composite powder was tested to be 3.3wt%;

[0077] S32: dry-grind and uniformly mix appropriate amounts of silicon composite powder containing boron and hydrogen and silicon powder (D50=250μm, oxygen content less than 500ppm, metal impurity content less than 100ppm) to obtain mixed powder (D50=155μm); wherein the boron content in the mixed powder is 297ppm;

[0078] S33: Install the processed back tube on the frame of the atmospheric plasma spraying equipment. The frame drives the back tube to rotate and move axially. The spray gun is installed 105mm above the central axis of the back tube. The moving speed of the spray gun is set to 50mm / s, the rotation speed of the back tube is 250r / min, the powder feeding amount is 150g / min, and water is passed into the back tube to make the temperature of the back tube surface 80℃. Under normal pressure and atmospheric atmosphere conditions, the mixed powder is sprayed onto the back tube for 2h to obtain a silicon target.

[0079] Comparative Example 1

[0080] This comparative example provides a method for preparing a silicon target material, which is different from Example 1 in that:

[0081] In step S13, “vacuum plasma spraying equipment” is used instead of “atmospheric plasma spraying equipment”, and “under the condition of normal pressure and atmospheric atmosphere” is replaced by “under the condition that the powder feeding gas and the working gas are both argon-hydrogen mixed gas (95% Ar+5% H2) and the pressure is 10 kPa”.

[0082] Comparative Example 2

[0083] This comparative example provides a method for preparing a silicon target material, comprising the following steps:

[0084] S1: Place appropriate amount of silicon powder (D50=250μm, oxygen content less than 500ppm, metal impurity content less than 100ppm) and boron powder (D50=8mm, oxygen content less than 500ppm, metal impurity content less than 100ppm) in a smelting furnace for high-temperature smelting to form silicon-boron ingots;

[0085] S2: Mechanically crushing, ball milling and sieving the silicon boron ingot to obtain silicon boron powder, and then drying the silicon boron powder at 100°C for 30 minutes to obtain a mixed powder (D50=158μm), wherein the boron content in the mixed powder is 152ppm;

[0086] S3: Install the processed back tube on the frame of the atmospheric plasma spraying equipment. The frame drives the back tube to rotate and move axially. The spray gun is installed 105mm above the central axis of the back tube. The moving speed of the spray gun is set to 50mm / s, the rotation speed of the back tube is 250r / min, the powder feeding amount is 150g / min, and water is passed into the back tube to make the surface temperature of the back tube 80℃. Under normal pressure and atmospheric atmosphere conditions, the mixed powder is sprayed onto the back tube for 2h to obtain a silicon target.

[0087] Comparative Example 3

[0088] This comparative example provides a method for preparing a silicon target material, comprising the following steps:

[0089] S1: Silicon powder (D50=250μm, oxygen content less than 500ppm, metal impurity content less than 100ppm), boron powder (D50=8mm, oxygen content less than 500ppm, metal impurity content less than 100ppm) and ethanol are ball-milled and mixed, and then polyvinyl alcohol is added and mixed evenly to obtain a slurry; the amount of polyvinyl alcohol added is 0.5% of the total mass of silicon powder and boron powder, and the solid content of the slurry is 75%;

[0090] S2: introducing the slurry into a centrifugal spray granulator, setting the inlet temperature to 200°C and the outlet temperature to 100°C, to obtain a mixed powder (D50=155μm), wherein the boron content in the mixed powder is 152ppm;

[0091] S3: Install the processed back tube on the frame of the atmospheric plasma spraying equipment. The frame drives the back tube to rotate and move axially. The spray gun is installed 105mm above the central axis of the back tube. The moving speed of the spray gun is set to 50mm / s, the rotation speed of the back tube is 250r / min, the powder feeding amount is 150g / min, and water is passed into the back tube to make the surface temperature of the back tube 80℃. Under normal pressure and atmospheric atmosphere conditions, the mixed powder is sprayed onto the back tube for 2h to obtain a silicon target.

[0092] Related performance test analysis:

[0093] 1. The thermal conductivity of the silicon target material prepared in Example 1 was tested using a thermal conductivity meter;

[0094] The thermal conductivity of the silicon target is 203 W / (m·K), which is significantly greater than that of the pure silicon target (about 148 W / (m·K)). This indicates that the boron atoms cracked by the gaseous borane can diffuse into the silicon powder through the grain boundaries to dope the silicon powder, thereby improving the thermal conductivity of the silicon target obtained later.

[0095] 2. The resistivity of the silicon targets prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested by a four-probe tester;

[0096] 3. The O content of the silicon targets prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested using an oxygen and nitrogen analyzer;

[0097] 4. Use ICP spectrometer to test the boron content in silicon target;

[0098] The test results are shown in Table 1 below:

[0099] Table 1

[0100]

[0101] It can be seen from Table 1 that the oxygen content and resistivity of the silicon target material prepared in Example 1 are basically the same as those in Comparative Example 1, indicating that the oxygen content and resistivity of the silicon target material prepared by thermal spraying in normal pressure and atmospheric atmosphere in the embodiment of the present application are basically the same as those of the silicon target material prepared by thermal spraying in an argon-hydrogen mixed atmosphere in the comparative example, indicating that thermal spraying of the mixed powder in the embodiment of the present application under normal pressure and atmosphere will not lead to an increase in the oxygen content and resistivity of the silicon target material. This is mainly because the silicon composite powder in the embodiment of the present application contains hydrogen, and hydrogen removal will occur during the thermal spraying process to release hydrogen to create a reducing environment, which can prevent silicon oxidation. Therefore, the embodiment of the present application can adopt atmospheric plasma spraying equipment and spray under normal pressure and atmospheric atmosphere, thereby reducing production costs.

[0102] The oxygen content and resistivity of the silicon target prepared in Examples 1 to 3 are significantly lower than those in Comparative Examples 2 and 3, indicating that the present application uses gaseous borane to diffuse boron into silicon powder, so that the obtained silicon composite powder contains hydrogen, so that hydrogen is removed during the spraying process to release hydrogen to create a reducing environment, which can prevent silicon oxidation. Therefore, the oxygen content of the silicon target in the present application embodiment is lower and the resistivity is also lower. Although Comparative Example 3 can remove part of the oxygen and purify the silicon powder and boron powder in the high-temperature smelting stage, no dehydrogenation and release of hydrogen protection occurs during the spraying process, which will cause the oxygen content of the silicon target to increase and the resistivity to increase.

[0103] The boron content of the silicon target materials prepared in Examples 1 to 3 is basically the same as the boron content of the mixed powder, while the boron content of the silicon target material prepared in Comparative Example 2 is significantly biased towards the boron content of the mixed powder. This is mainly because in Comparative Example 2, the silicon powder and boron powder are spray-granulated, which only physically combines silicon and boron. During the spraying process, it is impossible to ensure that boron and silicon are deposited together, thereby affecting the boron deposition rate.

[0104] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a silicon target, characterized in that: The following steps are involved: The first silicon powder is placed in a vacuum tube furnace, evacuated to 0.1-1.0 Pa, and then a mixed gas of reducing gas and gaseous borane is introduced to perform boron diffusion treatment for 0.5-1 h under the conditions of a pressure of 10-50 kPa and a temperature of 800-900° C., to obtain a silicon composite powder containing boron and hydrogen; The silicon composite powder containing boron and hydrogen and the second silicon powder are mixed by ball milling to obtain a mixed powder; The mixed powder is thermally sprayed onto a backing tube, and then machined to obtain a silicon target.

2. The preparation method according to claim 1, characterized in that The volume ratio of the reducing gas to the gaseous borane is (96-99) / (1-4); And / or, the flow rate of the mixed gas is 1~5mL / min.

3. The preparation method according to claim 1, characterized in that: The gaseous borane is selected from diborane or tetraborane; And / or, the reducing gas is selected from hydrogen.

4. The preparation method according to claim 2, characterized in that: One or more of the following conditions are met: The particle size of the first silicon powder is ≤300 μm; The boron content in the silicon composite powder containing boron and hydrogen is 1-3.5wt%; The particle size of the second silicon powder is ≤300 μm; The particle size of the mixed powder is 100-250 μm; The boron content in the mixed powder is 50-300 ppm.

5. The preparation method according to any one of claims 1 to 4, characterized in that The step of thermally spraying the mixed powder onto the back tube comprises: using atmospheric plasma spraying equipment to spray the mixed powder onto the back tube under normal pressure and atmospheric atmosphere.

6. The preparation method according to claim 5, characterized in that: The atmospheric plasma spraying equipment includes a spray gun, the distance between the spray gun and the central axis of the back tube is 95-115 mm, the moving speed of the spray gun is 30-80 mm / s, the rotation speed of the back tube is 200-300 r / mim, and the powder feeding amount is 100-200 g / min.

7. A silicon target material, characterized in that: Including the silicon target material prepared by the method for preparing the silicon target material according to any one of claims 1 to 6.

8. The silicon target material according to claim 7, characterized in that: The silicon target material has a boron content of 50-300 ppm, a resistivity of 0.01-0.5 Ω·cm, and a thermal conductivity of 200-300 W / (m·K).

9. An optical device comprising a silicon dioxide film layer, characterized in that: The silicon dioxide film layer is obtained by sputtering the silicon target material according to claim 7 or 8.

Images