A silicon target material with high electrical and thermal conductivity, a preparation method thereof, and an optical element

Abstract

The present application relates to the technical field of target material preparation, and provides a silicon target material with high electrical and thermal conductivity, a preparation method thereof and an optical element, including: subjecting a silicon target residue and boron powder to a first airflow crushing to obtain a silicon-boron mixed powder; subjecting the silicon-boron mixed powder to a hot pressing treatment to obtain a silicon-boron alloy ingot; subjecting the silicon-boron alloy ingot to mechanical crushing to less than 5 mm and then subjecting the second airflow crushing to classification to obtain a silicon-boron alloy coarse powder and a silicon-boron alloy fine powder; subjecting the silicon-boron alloy fine powder and a solvent to ball milling and mixing to form a slurry; spraying the slurry into the silicon-boron alloy coarse powder, and subjecting the rolling granulation to obtain a granulated powder; thermally spraying the granulated powder onto a back tube, and machining to obtain a silicon target material. The present application adds boron powder and a silicon target residue to airflow crushing, so that the silicon target residue crushing and the boron powder are evenly mixed, and then hot pressing is performed to form an alloy with the silicon-boron mixed powder, and then secondary airflow crushing is performed to make the boron distribution of the silicon-boron alloy powder more uniform, thereby achieving doping with trace boron to significantly improve the electrical and thermal conductivity 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 highly electrically and thermally conductive silicon target material, a preparation method thereof, and an optical element. Background Art

[0002] Silicon dioxide film has excellent optical properties, dielectric insulation, wear resistance and strong corrosion resistance. It has broad application prospects in optics, microelectronics and other fields and is a functional material that is currently receiving widespread attention internationally.

[0003] The magnetron sputtering method in PVD (physical vapor deposition) coating uses target materials as raw materials and does not require precursors. It has the advantages of good film quality, mature industrial production, and green environmental protection. It is often used to prepare silicon dioxide films. However, the utilization rate of sputtering targets is generally low, especially the utilization rate of planar targets is even lower. The remaining residual targets are usually disposed of as waste at a very low price. In the case of high-purity silicon powder / silicon ingot raw material prices, in order to achieve cost reduction and efficiency improvement, it is very necessary to recycle and reuse the silicon residual targets.

[0004] At present, the commonly used method for recycling silicon residual targets includes: soaking the silicon residual targets in an acidic solution, then washing, drying, crushing and screening, and then acid-washing, washing and drying the obtained silicon powder to obtain pure silicon powder. However, the target material prepared by thermal spraying of pure silicon powder has poor electrical and thermal conductivity, which results in the inability of the silicon target material to quickly transfer heat during the sputtering coating process, thereby affecting the service life of the silicon target material and the coating stability, and the sputtering power that can be tolerated is low, resulting in low silicon target coating efficiency. Therefore, how to dope the silicon residual targets in the process of recycling silicon residual targets to improve the electrical and thermal conductivity of the subsequently prepared silicon target materials is of great significance. Summary of the invention

[0005] The purpose of the present application is to provide a highly electrically conductive and thermally conductive silicon target material, a preparation method thereof, and an optical element, in order to solve the problem that the existing method for recycling silicon residual targets is unable to dope the silicon residual targets during the recycling process, resulting in poor electrical and thermal conductivity of the produced silicon target material, as well as low and unstable coating efficiency.

[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 highly electrically and thermally conductive silicon target material, comprising the following steps:

[0008] The silicon target residue and the boron powder are subjected to a first air flow pulverization to obtain a silicon-boron mixed powder;

[0009] The silicon-boron mixed powder is subjected to hot pressing to obtain a silicon-boron alloy ingot;

[0010] Mechanically crushing the silicon-boron alloy ingot to less than 5 mm, then performing a second air flow pulverization, and then classifying to obtain silicon-boron alloy coarse powder and silicon-boron alloy fine powder;

[0011] The silicon-boron alloy fine powder and the solvent are ball-milled to form a slurry;

[0012] The slurry is sprayed into the silicon-boron alloy coarse powder, and then rolling granulation is performed to obtain granulated powder;

[0013] The granulated powder is thermally sprayed onto a backing tube and then machined to obtain a silicon target.

[0014] In a second aspect, the present application provides a silicon target material with high electrical and thermal conductivity, including a silicon target material prepared by the method for preparing a silicon target material with high electrical and thermal conductivity provided in the present application;

[0015] The boron content in the silicon target material is 50-250 ppm, the resistivity is 0.01-0.5 Ω·cm, and the thermal conductivity is 200-300 W / m·K.

[0016] In a third aspect, the present application provides an optical element, comprising a silicon dioxide layer, wherein the silicon dioxide layer is obtained by sputtering and coating the highly conductive and thermally conductive silicon target material provided by the present application.

[0017] Compared with the prior art, this application has the following beneficial effects:

[0018] (1) Adding boron powder and silicon target residue together for air flow pulverization, the silicon target residue is pulverized and mixed evenly with the boron powder, which is conducive to hot pressing of the silicon-boron mixed powder to form a uniform silicon-boron alloy ingot. After secondary air flow pulverization, the boron is more evenly distributed in the silicon-boron alloy powder, so that the organization uniformity of the silicon target material is better, which is more conducive to improving the electrical and thermal conductivity of the silicon target material.

[0019] (2) Reducing the distance between powders through hot pressing can promote powder contact and diffusion, reduce sintering temperature and shorten sintering time, inhibit grain growth, and form a more uniform and dense silicon-boron alloy ingot, which is beneficial to improve the electrical and thermal conductivity of silicon target. At the same time, it can prevent boron from being separated during secondary airflow crushing, ensure that boron and silicon are deposited together, and make boron and silicon have the same deposition rate. Therefore, the boron content of silicon target can be accurately controlled to avoid incomplete silicon-boron alloying due to the relatively fluffy silicon powder and low bulk density, which affects the silicon deposition rate. And hot pressing makes the bulk density of silicon-boron alloy powder larger, which is beneficial to improve the density of silicon target.

[0020] (3) The slurry made from silicon-boron alloy fine powder is used as a binder. After rolling granulation, the silicon-boron alloy coarse powder is bonded to form granulated powder, which can improve the fluidity of the powder, which is beneficial to improving the spraying efficiency and improving the quality of the silicon target. In addition, there is no need to use organic binders and dispersants, the raw material cost is lower, the target purity is higher, and the purity, electrical and thermal conductivity of the silicon target will not be affected by incomplete degreasing. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] Figure 1 It is a process flow chart of the method for preparing a highly conductive and thermally conductive silicon target material provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] 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.

[0024] The first aspect of the present application provides a method for preparing a highly conductive and thermally conductive silicon target material, such as Figure 1 As shown, the following steps are included:

[0025] S01: subjecting the silicon target residue and the boron powder to a first airflow pulverization to obtain a silicon-boron mixed powder;

[0026] S02: hot pressing the silicon-boron mixed powder to obtain a silicon-boron alloy ingot;

[0027] S03: Mechanically crushing the silicon-boron alloy ingot to less than 5 mm, and then performing a second air flow crushing, and then classifying to obtain silicon-boron alloy coarse powder and silicon-boron alloy fine powder;

[0028] S04: ball-milling the silicon-boron alloy fine powder and the solvent to form a slurry;

[0029] S05: spraying the slurry into the silicon-boron alloy coarse powder, and then rolling granulating to obtain granulated powder;

[0030] S06: The granulated powder is thermally sprayed onto a backing tube, and then machined to obtain a silicon target.

[0031] The preparation method of the silicon target with high electrical and thermal conductivity provided by the embodiment of the present application, adds boron powder and silicon residual target to carry out air flow crushing together, so that the silicon residual target is crushed and mixed with boron powder evenly, which is conducive to hot pressing of silicon-boron mixed powder to form a uniform silicon-boron alloy ingot, and after secondary air flow crushing, boron is distributed more evenly in the silicon-boron alloy powder, so that the organization uniformity of the silicon target is better, which is more conducive to improving the electrical and thermal conductivity of the silicon target. Secondly, the powder spacing is reduced by hot pressing treatment, which can promote powder contact diffusion, and can also reduce the sintering temperature and shorten the sintering time, inhibit grain growth, and form a more uniform and dense silicon-boron alloy ingot, which is conducive to improving the electrical and thermal conductivity of the silicon target. At the same time, it can also prevent boron from being separated during secondary air flow crushing, ensure that boron and silicon are deposited together, so that boron and silicon have the same deposition rate, so that the boron content of the silicon target can be accurately controlled, and the silicon powder is relatively fluffy and the loose density is small, and the silicon-boron alloy is not completely alloyed to affect the deposition rate of silicon; and the loose density of the silicon-boron alloy powder is made larger by hot pressing, which is conducive to improving the density of the silicon target. In addition, the slurry made from silicon-boron alloy fine powder is used as a binder. After rolling granulation, the silicon-boron alloy coarse powder is bonded to form granulated powder, which can improve the fluidity of the powder, which is beneficial to improving the spraying efficiency and improving the quality of the silicon target material. There is no need to use organic binders and dispersants, the raw material cost is lower, the target material purity is higher, and the purity, electrical and thermal conductivity of the silicon target material will not be affected by incomplete degreasing.

[0032] The above-mentioned step S01, before the step of subjecting the silicon residual target and the boron powder to the first airflow crushing step, also includes: acid soaking, water washing and drying the silicon residual target to remove metal impurities and oxides on the surface of the silicon residual target, so that the oxygen content of the silicon residual target is less than 500ppm, and the metal impurity content is less than 100ppm; then mechanically crushing it to less than 5mm, so that the airflow crusher can crush the silicon residual target.

[0033] In an embodiment, the oxygen content of the boron powder is less than 500 ppm, and the metal impurity content is less than 100 ppm.

[0034] In the embodiment, the particle size of the silicon-boron mixed powder is 5-45 μm. This particle size range can both reduce oxidation of the silicon-boron mixed powder as much as possible and ensure low oxygen content of the silicon-boron mixed powder, and is conducive to hot pressing sintering, promoting contact and diffusion of the powder to form an alloy.

[0035] In the embodiment, the boron content in the silicon-boron mixed powder is 50-250 ppm. This boron content range can not only give the silicon target material excellent electrical and thermal conductivity, but also does not affect the optical properties of the silicon target material coating, so that the optical transmittance of the coating is high.

[0036] The above step S02, the step of hot pressing the silicon-boron mixed powder includes: placing the silicon-boron mixed powder into a mold and placing it in a hot pressing furnace, performing pre-pressing at a pressure of 5-10MPa, then evacuating to below 1Pa, heating to 1000-1200°C, and then pressurizing to 10-20MPa for hot pressing for 0.5-1.5h. The air between the silicon-boron mixed powder is first removed by pre-pressing to reduce the oxygen content of the blank, thereby helping to reduce the oxygen content of the silicon target. And evacuating to below 1Pa and then heating for hot pressing can prevent silicon oxidation, thereby further reducing the oxygen content of the silicon target.

[0037] In the embodiment, the relative density of the silicon-boron alloy ingot is 80~95%. This relative density range can prevent the boron from being separated during the secondary airflow crushing of the silicon-boron alloy ingot, ensure that the boron and silicon in the silicon-boron alloy powder are deposited together, and make the boron and silicon have the same deposition rate, so that the boron content of the silicon target can be accurately controlled. In addition, the loose density of the silicon-boron alloy powder is relatively large, which helps to improve the density of the spray target.

[0038] In the embodiment, the particle size of the silicon-boron alloy coarse powder is 0.5-45 μm; the particle size of the silicon-boron alloy fine powder is less than 0.5 μm, preferably 0.3-0.5 μm. The particle size range of the silicon-boron alloy coarse powder and the silicon-boron alloy fine powder can not only reduce the oxidation of the powder as much as possible to ensure the low oxygen content of the silicon-boron mixed powder, but also facilitate the silicon-boron alloy coarse powder to be bonded by the silicon-boron alloy fine powder to form granulated powder.

[0039] In the embodiment, the mass ratio of the silicon-boron alloy coarse powder to the silicon-boron alloy fine powder is (80-95) / (5-20). This mass range is conducive to rolling granulation of the two to form granulated powder with good fluidity.

[0040] In an embodiment, the solvent is selected from terpineol.

[0041] In the embodiment, the solid content of the slurry is 35-40%.

[0042] In the above step S04, in the embodiment, the step of thermally spraying the granulation powder onto the back tube includes: using vacuum plasma spraying equipment, in an argon-hydrogen mixed atmosphere with a volume ratio of argon to hydrogen of (90-99) / (1-10), spraying the granulation powder onto the back tube. Among them, the volume ratio of argon to hydrogen in the argon-hydrogen mixed gas can also be preferably (90-95) / (5-10). Using vacuum plasma spraying equipment and feeding and spraying powder in an argon-hydrogen mixed atmosphere can prevent the oxidation of the granulation powder and reduce the oxygen content of the silicon target.

[0043] In an embodiment, the vacuum 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 granulated powder. Therefore, within the spray gun distance range of this embodiment, the granulated powder has a higher deposition rate, and the silicon target has a higher density and stronger mechanical strength.

[0044] The moving speed of the spray gun is 30~80mm / s. Within this moving speed range, the granulation 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.

[0045] The rotation speed of the back tube is 200~300r / mim. Within this rotation speed range, the granulation 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.

[0046] The powder feeding amount is 100~200g / min. This powder feeding amount range can ensure a higher spraying efficiency, and is also conducive to the granulation powder being evenly sprayed onto the back tube to form a uniform and dense silicon target.

[0047] 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.

[0048] A second aspect of an embodiment of the present application provides a highly electrically conductive and thermally conductive silicon target material, including a silicon target material prepared by the method for preparing a highly electrically conductive and thermally conductive silicon target material provided in an embodiment of the present application; wherein the boron content in the silicon target material is 50~250ppm, the resistivity is 0.01~0.5Ω·cm, and the thermal conductivity is 200~300W / (m·K).

[0049] The highly conductive and thermally conductive 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. Therefore, the silicon target material has good conductive and thermal conductivity and high density, and can withstand high power. Therefore, the silicon target material coating efficiency is high and stability is good, and the film quality is good and the optical transmittance is high.

[0050] A third aspect of an embodiment of the present application provides an optical element, comprising a silicon dioxide layer, wherein the silicon dioxide layer is obtained by sputtering and coating the highly conductive and thermally conductive silicon target material provided by an embodiment of the present application.

[0051] The optical element 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 layer contained in it is obtained by sputtering and coating the silicon target material provided in the present application.

[0052] The following describes the invention in conjunction with specific embodiments.

[0053] Example 1

[0054] This embodiment provides a method for preparing a silicon target material with high electrical and thermal conductivity, comprising the following steps:

[0055] S11: Soak the silicon residual target in 15% hydrochloric acid for 8 hours, wash with water, and dry to obtain a silicon residual target with an oxygen content of less than 500ppm and a metal impurity content of less than 100ppm; mechanically crush the silicon residual target to less than 5mm, and then put it into a jet mill with boron powder for the first jet milling to obtain silicon-boron mixed powder (D50=33μm, boron content of 184ppm);

[0056] S12: The silicon-boron mixed powder is loaded into a mold and placed in a hot pressing furnace for pre-pressing at a pressure of 8 MPa, and then evacuated to 0.5 Pa, and then the temperature is raised to 1100° C., and then the pressure is increased to 15 MPa for hot pressing for 1 hour to obtain a silicon-boron alloy ingot;

[0057] The relative density of silicon-boron alloy ingots was tested to be 89.6%;

[0058] S13: The silicon-boron alloy ingot is mechanically crushed to less than 5 mm by a hammer crusher, and then loaded into a jet mill for second jet milling, and then classified to obtain silicon-boron alloy coarse powder (D50=29μm) and silicon-boron alloy fine powder (D50=0.4μm) with a mass ratio of 88.3 / 11.7;

[0059] S14: adding the silicon-boron alloy fine powder to pine alcohol and performing ball milling to obtain a slurry with a solid content of 38%;

[0060] S15: loading the silicon-boron alloy coarse powder into a three-dimensional mixer, then spraying the slurry into the mixer, and then performing three-dimensional rolling granulation to obtain granulated powder;

[0061] S16: Install the processed back tube on the frame of the vacuum 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 movement 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°C. In an argon-hydrogen mixed atmosphere with a volume ratio of argon to hydrogen of 94 / 6, the granulated powder is sprayed onto the back tube for 2h to obtain a silicon target.

[0062] Example 2

[0063] This embodiment provides a method for preparing a silicon target material with high electrical and thermal conductivity, which is different from Embodiment 1 in that:

[0064] S12: The silicon-boron mixed powder is loaded into a mold and placed in a hot pressing furnace for pre-pressing at a pressure of 5 MPa, and then evacuated to 0.5 Pa, and then the temperature is raised to 1000° C., and then the pressure is increased to 10 MPa for hot pressing for 0.5 h to obtain a silicon-boron alloy ingot;

[0065] The relative density of the silicon-boron alloy ingot was tested to be 81.2%.

[0066] Example 3

[0067] This embodiment provides a method for preparing a silicon target material with high electrical and thermal conductivity, which is different from Embodiment 1 in that:

[0068] S12: The silicon-boron mixed powder is loaded into a mold and placed in a hot pressing furnace for pre-pressing at a pressure of 10 MPa, and then evacuated to 0.5 Pa, and then the temperature is raised to 1200° C., and then the pressure is increased to 20 MPa for hot pressing for 1.5 hours to obtain a silicon-boron alloy ingot;

[0069] The relative density of the silicon-boron alloy ingot was tested to be 94.5%.

[0070] Comparative Example 1

[0071] This comparative example provides a method for preparing a silicon target material with high electrical and thermal conductivity, which is different from Example 1 in that:

[0072] Steps S12 and S13 are replaced by: loading the silicon-boron mixed powder into a vacuum sintering furnace, evacuating to 0.5 Pa, starting to heat up to 1250°C, keeping warm for 6 hours, and then crushing and sieving to obtain silicon-boron alloy coarse powder (D50=29μm) and silicon-boron alloy fine powder (D50=0.4μm) with a mass ratio of 89.1 / 10.9.

[0073] Comparative Example 2

[0074] This comparative example provides a method for preparing a silicon target material with high electrical and thermal conductivity, which is different from Example 1 in that:

[0075] Steps S13 to S15 are replaced by: using a hammer crusher to mechanically crush the silicon-boron alloy ingot to less than 5 mm, and then loading it into a jet mill for second jet milling to obtain silicon-boron alloy powder (D50=27 μm);

[0076] The silicon-boron alloy powder and pine alcohol are ball-milled and mixed, and then polyvinyl alcohol is added and mixed evenly to obtain a slurry;

[0077] The slurry was introduced into a spray granulator for granulation, and then placed in a vacuum sintering furnace for degreasing at a vacuum degree of 0.5 Pa and 500° C. for 6 h to obtain granulated powder.

[0078] Comparative Example 3

[0079] This comparative example provides a method for preparing a silicon target material, comprising the following steps:

[0080] S1: Soak the silicon residual target in 15% hydrochloric acid for 8 hours, wash with water, and dry to obtain a silicon residual target with an oxygen content of less than 500ppm and a metal impurity content of less than 100ppm; mechanically crush the silicon residual target to less than 5mm, and then put it into a jet mill for the first jet milling to obtain silicon powder (D50=75μm);

[0081] S2: ball-mill and mix silicon powder and boron powder (oxygen content less than 500ppm, metal impurity content less than 100ppm) to obtain silicon-boron mixed powder (D50=34μm, boron content 184ppm);

[0082] S3: Install the processed back tube on the frame of the vacuum 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 movement 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℃. In an argon-hydrogen mixed atmosphere with a volume ratio of argon to hydrogen of 94 / 6, boron-doped silicon powder is sprayed onto the back tube for 2h to obtain a silicon target.

[0083] Comparative Example 4

[0084] This comparative example provides a method for preparing a silicon target material with high electrical and thermal conductivity, comprising the following steps:

[0085] S1: placing silicon powder (oxygen content less than 500ppm, metal impurity content less than 100ppm) and boron powder (oxygen content less than 500ppm, metal impurity content less than 100ppm) in a smelting furnace for high-temperature smelting to form silicon-boron ingots;

[0086] S2: Mechanically crush, ball-mill and sieve the silicon-boron ingot, and then dry the sieved powder at 100°C for 30 minutes to obtain silicon-boron alloy powder (D50=125μm, boron content of 184ppm);

[0087] S3: Install the processed back tube on the frame of the vacuum 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 movement 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℃. In an argon-hydrogen mixed atmosphere with a volume ratio of argon to hydrogen of 94 / 6, silicon-boron alloy powder is sprayed onto the back tube for 2h to obtain a silicon target.

[0088] Related performance test analysis:

[0089] 1. The thermal conductivity of the silicon target material prepared in Example 1 was tested using a thermal conductivity meter;

[0090] The thermal conductivity of the silicon target is 215 W / (m·K), which is significantly greater than that of the pure silicon target (about 148 W / (m·K)). This indicates that the embodiment of the present application adds boron powder and performs airflow crushing together with the silicon residual target, and the silicon residual target can be crushed and mixed with the boron powder evenly. The silicon-boron mixed powder is formed into an alloy through hot pressing treatment, and the boron distribution of the silicon-boron alloy powder is more uniform through secondary airflow crushing, thereby achieving the significant improvement of the electrical and thermal conductivity of the silicon target by doping with trace boron.

[0091] 2. The resistivity of the silicon targets prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was tested using a four-probe tester;

[0092] 3. The boron content of the silicon targets prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was tested by ICP spectrometer respectively;

[0093] 4. The actual density of the silicon target materials prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was tested respectively by the Archimedes density test method. The theoretical density was used as a reference. Relative density = actual density / theoretical density × 100%;

[0094] The test results are shown in Table 1 below:

[0095] Table 1

[0096]

[0097] It can be seen from Table 1 that the boron content of the silicon target materials prepared in Examples 1 to 3 is substantially the same as that of the silicon-boron mixed powder, while the boron content of the silicon target material prepared in Comparative Example 3 is significantly lower than that of the silicon-boron mixed powder, indicating that the embodiments of the present application can form an alloy with the silicon-boron mixed powder by adding boron powder and performing airflow crushing together with the silicon residual target, and then subjecting the mixture to hot pressing treatment, thereby preventing the boron from being separated during the secondary airflow crushing of the silicon-boron alloy ingot, and allowing the boron and silicon to be deposited together with the same deposition rate, thereby being able to accurately control the boron content of the silicon target material.

[0098] The boron content of the silicon target prepared in Comparative Example 1 is lower than the boron content of the silicon-boron mixed powder, and the relative density is significantly lower than that of Examples 1 to 3. This is mainly because the silicon powder is relatively fluffy and has a small bulk density. In the absence of applied pressure, the bulk density of the silicon-boron alloy powder obtained by high-temperature calcination is small, which affects the density of the silicon target and is difficult to fully alloy, thereby affecting the deposition rate of silicon, causing the boron content of the silicon target to deviate from the boron content of the silicon-boron mixed powder.

[0099] The resistivity of the silicon target materials prepared in Examples 1 to 3 is greater than that in Comparative Example 2. This is mainly because polyvinyl alcohol (binder) is added to granulate in Comparative Example 2, which may result in incomplete degreasing, thus affecting the resistivity of the silicon target material.

[0100] The resistivity and relative density of the silicon target prepared in Examples 1 to 3 are better than those in Comparative Example 4, indicating that the embodiments of the present application not only make the boron evenly distributed in the silicon-boron alloy powder by adding boron powder and the silicon residual target together with airflow crushing, and then undergo hot pressing and secondary airflow crushing, which is conducive to reducing the resistivity of the silicon target, but also the obtained silicon-boron alloy powder has a larger bulk density, so the silicon target has a higher relative density. However, the silicon-boron ingot obtained by high-temperature smelting in Comparative Example 4 may have pores, etc., so that the bulk density of the crushed silicon-boron alloy powder is relatively small, thereby affecting the relative density of the silicon target.

[0101] 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 highly conductive and thermally conductive silicon target material, characterized in that: The following steps are involved: The silicon target residue and the boron powder are subjected to a first air flow pulverization to obtain a silicon-boron mixed powder; The silicon-boron mixed powder is subjected to hot pressing to obtain a silicon-boron alloy ingot; Mechanically crushing the silicon-boron alloy ingot to less than 5 mm, then performing a second air flow pulverization, and then classifying to obtain silicon-boron alloy coarse powder and silicon-boron alloy fine powder; the particle size of the silicon-boron alloy coarse powder is 0.5-45 μm; the particle size of the silicon-boron alloy fine powder is less than 0.5 μm; the mass ratio of the silicon-boron alloy coarse powder to the silicon-boron alloy fine powder is (80-95) / (5-20); The silicon-boron alloy fine powder and the solvent are ball-milled to form a slurry; the solid content of the slurry is 35-40%; The slurry is sprayed into the silicon-boron alloy coarse powder, and then rolling granulation is performed to obtain granulated powder; The granulated 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 particle size of the silicon-boron mixed powder is 5-45 μm; And / or, the boron content in the silicon-boron mixed powder is 50-250 ppm.

3. The preparation method according to claim 1, characterized in that: The step of hot pressing the silicon-boron mixed powder comprises: The silicon-boron mixed powder is loaded into a mold and placed in a hot pressing furnace for pre-pressing at a pressure of 5-10 MPa, then evacuated to below 1 Pa, heated to 1000-1200° C., and then pressurized to 10-20 MPa for hot pressing for 0.5-1.5 h.

4. The preparation method according to claim 1, characterized in that: The relative density of the silicon-boron alloy ingot is 80-95%.

5. The preparation method according to claim 1, characterized in that: The solvent is selected from terpineol.

6. The preparation method according to claim 1, characterized in that: Before the step of subjecting the silicon residual target and the boron powder to the first airflow pulverization, the method further includes: acid soaking, water washing and drying the silicon residual target, and then mechanically crushing the target to less than 5 mm.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The step of thermally spraying the granulation powder onto the back tube comprises: using vacuum plasma spraying equipment, in an argon-hydrogen mixed atmosphere with a volume ratio of argon to hydrogen of (90-99) / (1-10), spraying the granulation powder onto the back tube.

8. The preparation method according to claim 7, characterized in that The vacuum 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.

9. A highly conductive and thermally conductive silicon target, characterized in that: A silicon target material obtained by the method for preparing a silicon target material with high electrical and thermal conductivity according to any one of claims 1 to 8; The boron content in the silicon target material is 50-250 ppm, the resistivity is 0.01-0.5 Ω·cm, and the thermal conductivity is 200-300 W / m·K.

10. An optical element comprising a silicon dioxide layer, characterized in that: The silicon dioxide layer is obtained by sputtering the highly conductive and thermally conductive silicon target material as claimed in claim 9.

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