Method and device for dehydrogenating granular silicon surface

Abstract

The present invention provides a method for dehydrogenating the surface of granular silicon, comprising the following steps: S1: providing a sealed reaction container, a cover plate, an ultraviolet light source and an ozone generator, wherein the ozone generator is connected to the inside of the sealed reaction container, the ultraviolet light source is used to provide ultraviolet light into the sealed reaction container, the cover plate is movably arranged on the top of the sealed reaction container, and the granular silicon to be surface dehydrogenated is laid on the bottom of the sealed reaction container; S2: turning on the ozone generator to allow ozone gas to continuously pass into the inside of the sealed reaction container, and turning on the ultraviolet light source at the same time, irradiating the surface of the granular silicon with ultraviolet light, and after the irradiation is completed, turning off the ultraviolet light source, taking out the granular silicon, and completing the surface dehydrogenation. The present invention also provides a device for dehydrogenating the surface of granular silicon, and the present invention provides a method for dehydrogenating the surface of granular silicon with lower cost, simple operation, short processing time and low energy consumption.

Description

Technical Field

[0001] The present invention relates to the field of granular silicon surface dehydrogenation, and in particular to a method and device for granular silicon surface dehydrogenation. Background Art

[0002] At present, the preparation technology of high-purity polysilicon mainly includes the modified Siemens method and the fluidized bed method. The modified Siemens method is a closed-loop Siemens method, which uses the reaction of metal silicon powder and HCl to generate SiHCl3, which is then distilled and purified, and then high-purity polysilicon is obtained by H2 reduction deposition. The modified Siemens method currently occupies the highest market share, but this method has low production efficiency, high energy consumption, and high fixed investment. The fluidized bed method generally uses SiH4 or SiCl4 as the silicon source gas and hydrogen as the carrier gas. It undergoes a chemical vapor deposition reaction at 500-700 degrees and grows on the silicon powder pre-set in the fluidized bed. As the reaction proceeds, the grown granular silicon product is continuously discharged at the bottom of the fluidized bed, and a small amount of about 5%-15% of silicon powder by-products is generated. The fluidized bed method has a simple equipment structure, low investment, and high production efficiency, but it is easy to cause impurity contamination, which reduces the purity of the product. Due to the large specific surface area of ​​granular silicon, it is easy to introduce silicon-hydrogen bonds on its surface during the growth process. When this type of hydrogen-containing granular silicon material is used to draw solar single crystal rods, after the granular silicon is melted under low pressure, hydrogen atoms overflow from the silicon liquid in the form of gas, and in the process of overflow, the silicon liquid is splashed onto the graphite parts in the single crystal furnace, thereby damaging the parts inside the furnace and also adversely affecting the internal quality of the silicon crystal. This is the so-called "hydrogen jump phenomenon."

[0003] At present, the industry mainly uses high-temperature heating (above 800°C) to remove hydrogen. This method takes a long time (up to several hours) and consumes a lot of energy, which greatly increases the production cost of granular silicon materials. In order to save this part of the cost, granular silicon material manufacturers can only choose to abandon this method of dehydrogenation, which leads to the frequent occurrence of hydrogen jumps in the process of direct-pull single crystals. This phenomenon is particularly obvious during the secondary feeding of RCz and the continuous feeding of CCz. Based on the above problems, direct-pull single crystal companies currently generally use granular silicon as an additive, basically controlling the doping ratio below 30%. The doping ratio of the current leading silicon wafer factories is only about 40%. Affecting the large-scale use of granular silicon materials. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for dehydrogenating the surface of granular silicon to solve the problems of high cost, high energy consumption and general surface dehydrogenation effect of conventional methods.

[0005] In order to solve the above problems, the present invention provides a method for dehydrogenating the surface of granular silicon, comprising the following steps:

[0006] S1: providing a sealed reaction container, a cover plate, an ultraviolet light source and an ozone generator, wherein the ozone generator is connected to the inside of the sealed reaction container, the ultraviolet light source is used to provide ultraviolet light into the sealed reaction container, the cover plate is movably arranged on the top of the sealed reaction container, and granular silicon to be surface-dehydrogenated is laid on the bottom of the sealed reaction container;

[0007] S2: Turn on the ozone generator to allow ozone gas to continuously flow into the sealed reaction container, and at the same time turn on the ultraviolet light source to irradiate the surface of the granular silicon with ultraviolet light. After the irradiation is completed, turn off the ultraviolet light source, take out the granular silicon, and complete the surface dehydrogenation.

[0008] As a preferred solution, in the step S1, the granular silicon is laid in multiple layers on the bottom of the sealed reaction container by stacking, and the height of the granular silicon is lower than the ultraviolet light source.

[0009] As a preferred solution, in step S2, the flow rate of the ozone generator is 2-10 g / h, the power of the ultraviolet light source is 50-100 W, and the irradiation time is 30-90 minutes.

[0010] As a preferred solution, in step S2, the flow rate of the ozone generator is 3-5 g / h, the power of the ultraviolet light source is 60-90 W, and the irradiation time is 50-70 minutes.

[0011] As a preferred solution, in step S2, the flow rate of the ozone generator is 4 g / h, the power of the ultraviolet light source is 80 W, and the irradiation time is 60 minutes.

[0012] Another technical problem to be solved by the present invention is to provide a granular silicon surface dehydrogenation device to solve the problem that conventional devices have average dehydrogenation effects, high costs, and high energy consumption.

[0013] In order to solve the above problems, the present invention provides a granular silicon surface dehydrogenation device, which is suitable for the above method, and includes a sealed reaction container, a cover plate, an ultraviolet light source and an ozone generator. The cover plate is movably arranged on the top of the sealed reaction container, the ozone generator is connected to the interior of the sealed reaction container through a connecting pipe, and the ultraviolet light source is used to provide ultraviolet rays into the sealed reaction container.

[0014] As a preferred solution, the ultraviolet light source is arranged outside the sealed reaction container, and the sealed reaction container and the cover plate are made of transparent material.

[0015] As a preferred solution, the ultraviolet light source is arranged inside the sealed reaction container, and the ultraviolet light source is fixed to the bottom of the cover plate, and the sealed reaction container and the cover plate are made of opaque material.

[0016] The ultraviolet light source can be arranged inside / outside the sealed reaction container as required. Placing it inside the reaction container can enhance the integrity of the device and facilitate operation by operators, while placing it outside the reaction container can increase the carrying capacity of the container.

[0017] The present invention uses a method of ultraviolet-ozone radiation to remove hydrogen from granular silicon. By continuously introducing ozone gas into a container containing granular silicon, ozone undergoes photolysis under ultraviolet light to form atomic oxygen and molecular oxygen, wherein atomic oxygen is a very active active particle, and as the irradiation time increases, the concentration of active atomic oxygen in the container gradually increases, thereby exposing the surface of the granular silicon to an active environment formed by ultraviolet-ozone. The active atomic oxygen reacts with Si-H on the silicon surface through a gas phase oxidation process, causing Si-H to break, thereby causing H atoms to gradually convert into water vapor and overflow from the gap between the cover plate and the reaction container (the entire environment will heat up after ultraviolet light irradiation). Meanwhile, the specific reaction steps of step S2 are as follows:

[0018] O3+hv(ultraviolet light)→O+O2;

[0019] O+Si-H→Si+H2O.

[0020] The method for dehydrogenating the surface of granular silicon of the present invention adopts an ultraviolet-ozone radiation method. Compared with the prior art, it can shorten the heating dehydrogenation time, save energy, reduce the processing cost, increase the use ratio of granular silicon, reduce the hydrogen jump phenomenon in the single crystal pulling process, improve the quality of silicon crystals, and reduce the loss rate of single crystal furnace components. The process is simple, the price is low, the conditions are mild, and it has more efficiency and lower cost than high-temperature heat treatment when removing hydrogen impurities on the surface of granular silicon, and has strong application prospects and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The schematic diagram of the structure of the device in which the ultraviolet light source is arranged in a sealed reaction container;

[0022] Figure 2 The schematic diagram of the structure of the device in which the ultraviolet light source is arranged outside the sealed reaction container;

[0023] In the figure, 1. sealed reaction container; 2. ultraviolet light source; 3. cover plate; 4. ozone generator; 5. connecting pipe. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The present invention provides a method for dehydrogenating the surface of granular silicon, comprising the following steps:

[0026] S1: providing a sealed reaction container 1, a cover plate 3, an ultraviolet light source 2 and an ozone generator 4, wherein the ozone generator 4 is connected to the inside of the sealed reaction container 1, the ultraviolet light source 2 is used to provide ultraviolet light into the sealed reaction container 1, the cover plate 3 is movably arranged on the top of the sealed reaction container 1, and granular silicon to be surface-dehydrogenated is laid on the bottom of the sealed reaction container 1;

[0027] S2: Turn on the ozone generator 4 to allow ozone gas to continuously flow into the sealed reaction container 1, and at the same time turn on the ultraviolet light source 2 to irradiate the surface of the granular silicon with ultraviolet light. After the irradiation is completed, turn off the ultraviolet light source 2, take out the granular silicon, and complete the surface dehydrogenation.

[0028] Preferably, in the step S1 , the granular silicon is laid in multiple layers on the bottom of the sealed reaction container 1 by stacking, and the height of the granular silicon is lower than the ultraviolet light source 2 .

[0029] Preferably, in step S2, the flow rate of the ozone generator is 2-10 g / h, the power of the ultraviolet light source is 50-100 W, and the irradiation time is 30-90 minutes.

[0030] Preferably, in step S2, the flow rate of the ozone generator is 3-5 g / h, the power of the ultraviolet light source is 60-90 W, and the irradiation time is 50-70 minutes.

[0031] Preferably, in step S2, the flow rate of the ozone generator is 4 g / h, the power of the ultraviolet light source is 80 W, and the irradiation time is 60 minutes.

[0032] Preferably, the reaction process of step S2 is as follows: O3+hv (ultraviolet light)→O+O2; O+Si-H→Si+H2O.

[0033] The present invention also provides a granular silicon surface dehydrogenation device, which is suitable for the above method, comprising a sealed reaction container 1, a cover plate 3, an ultraviolet light source 2 and an ozone generator 4, wherein the cover plate 3 is movably arranged on the top of the sealed reaction container 1, the ozone generator 4 is connected to the inside of the sealed reaction container 1 through a connecting pipe 5, and the ultraviolet light source 2 is used to provide ultraviolet rays to the sealed reaction container 1.

[0034] Preferably, Figure 2 As shown, the ultraviolet light source 2 is arranged outside the sealed reaction container 1, and the sealed reaction container 1 and the cover plate 3 are made of transparent material.

[0035] Preferably, Figure 1 As shown, the ultraviolet light source 2 is disposed inside the sealed reaction container 1 , and the ultraviolet light source 2 is fixed to the bottom of the cover plate 3 .

[0036] The following is a description of the above solution of the present invention in combination with specific data:

[0037] Embodiment 1:

[0038] This embodiment provides a method for dehydrogenating the surface of granular silicon, comprising the following steps:

[0039] S1: providing a sealed reaction container 1, a cover plate 3, an ultraviolet light source 2 and an ozone generator 4, wherein the ozone generator 4 is connected to the inside of the sealed reaction container 1, the ultraviolet light source 2 is used to provide ultraviolet light into the sealed reaction container 1, the cover plate 3 is movably arranged on the top of the sealed reaction container 1, and granular silicon to be surface dehydrogenated is laid on the bottom of the sealed reaction container 1, the granular silicon is laid on the bottom of the sealed reaction container 1 in a stacked manner in multiple layers, and the height of the granular silicon is lower than the ultraviolet light source 2, and the hydrogen content of the granular silicon is 50ppmw;

[0040] S2: Turn on the ozone generator 4 to allow ozone gas to continuously flow into the sealed reaction container 1, and turn on the ultraviolet light source 2 at the same time. The flow rate of the ozone generator is 2g / h, the power of the ultraviolet light source is 50W, and the irradiation time is 30 minutes. Ultraviolet rays are irradiated on the surface of the granular silicon. After the irradiation, turn off the ultraviolet light source 2, take out the granular silicon, and complete the surface dehydrogenation. The hydrogen content of the granular silicon after dehydrogenation is 10ppmw.

[0041] The reaction process of step S2 is as follows: O3+hv (ultraviolet light)→O+O2; O+Si-H→Si+H2O.

[0042] The present invention also provides a granular silicon surface dehydrogenation device, which is suitable for the above method, comprising a sealed reaction container 1, a cover plate 3, an ultraviolet light source 2 and an ozone generator 4, wherein the cover plate 3 is movably arranged on the top of the sealed reaction container 1, the ozone generator 4 is connected to the inside of the sealed reaction container 1 through a connecting pipe 5, and the ultraviolet light source 2 is used to provide ultraviolet rays into the sealed reaction container 1. Figure 2 As shown, the ultraviolet light source 2 is arranged outside the sealed reaction container 1, and the sealed reaction container 1 and the cover plate 3 are made of opaque material.

[0043] Embodiment 2:

[0044] This embodiment provides a method for dehydrogenating the surface of granular silicon, comprising the following steps:

[0045] S1: providing a sealed reaction container 1, a cover plate 3, an ultraviolet light source 2 and an ozone generator 4, wherein the ozone generator 4 is connected to the inside of the sealed reaction container 1, the ultraviolet light source 2 is used to provide ultraviolet light into the sealed reaction container 1, the cover plate 3 is movably arranged on the top of the sealed reaction container 1, and granular silicon to be surface dehydrogenated is laid on the bottom of the sealed reaction container 1, the granular silicon is laid on the bottom of the sealed reaction container 1 in a stacked manner in multiple layers, and the height of the granular silicon is lower than the ultraviolet light source 2, the hydrogen content of the granular silicon is 50ppmw, and the hydrogen content of the granular silicon after dehydrogenation is 8ppmw;

[0046] S2: Turn on the ozone generator 4 to allow ozone gas to continuously flow into the sealed reaction vessel 1, and turn on the ultraviolet light source 2 at the same time. The flow rate of the ozone generator is 10g / h, the power of the ultraviolet light source is 90W, and the irradiation time is 70 minutes. Ultraviolet rays are irradiated on the surface of the granular silicon. After the irradiation is completed, turn off the ultraviolet light source 2, take out the granular silicon, and complete the surface dehydrogenation.

[0047] The reaction process of step S2 is as follows: O3+hv (ultraviolet light)→O+O2; O+Si-H→Si+H2O.

[0048] The present invention also provides a granular silicon surface dehydrogenation device, which is suitable for the above method, comprising a sealed reaction container 1, a cover plate 3, an ultraviolet light source 2 and an ozone generator 4, wherein the cover plate 3 is movably arranged on the top of the sealed reaction container 1, the ozone generator 4 is connected to the inside of the sealed reaction container 1 through a connecting pipe 5, and the ultraviolet light source 2 is used to provide ultraviolet rays into the sealed reaction container 1. Figure 1 As shown, the ultraviolet light source 2 is disposed inside the sealed reaction container 1 , and the ultraviolet light source 2 is fixed to the bottom of the cover plate 3 .

[0049] Embodiment 3:

[0050] This embodiment provides a method for dehydrogenating the surface of granular silicon, comprising the following steps:

[0051] S1: providing a sealed reaction container 1, a cover plate 3, an ultraviolet light source 2 and an ozone generator 4, wherein the ozone generator 4 is connected to the inside of the sealed reaction container 1, the ultraviolet light source 2 is used to provide ultraviolet light into the sealed reaction container 1, the cover plate 3 is movably arranged on the top of the sealed reaction container 1, and granular silicon to be surface dehydrogenated is laid on the bottom of the sealed reaction container 1, the granular silicon is laid on the bottom of the sealed reaction container 1 in a stacked manner in multiple layers, and the height of the granular silicon is lower than the ultraviolet light source 2, the hydrogen content of the granular silicon is 50ppmw, and the hydrogen content of the granular silicon after dehydrogenation is 8ppmw;

[0052] S2: Turn on the ozone generator 4 to allow ozone gas to continuously flow into the sealed reaction container 1, and turn on the ultraviolet light source 2 at the same time. The flow rate of the ozone generator is 4g / h, the power of the ultraviolet light source is 80W, and the irradiation time is 60 minutes. Ultraviolet rays are irradiated on the surface of the granular silicon. After the irradiation is completed, turn off the ultraviolet light source 2, take out the granular silicon, and complete the surface dehydrogenation.

[0053] The reaction process of step S2 is as follows: O3+hv (ultraviolet light)→O+O2; O+Si-H→Si+H2O.

[0054] The present invention also provides a granular silicon surface dehydrogenation device, which is suitable for the above method, comprising a sealed reaction container 1, a cover plate 3, an ultraviolet light source 2 and an ozone generator 4, wherein the cover plate 3 is movably arranged on the top of the sealed reaction container 1, the ozone generator 4 is connected to the inside of the sealed reaction container 1 through a connecting pipe 5, and the ultraviolet light source 2 is used to provide ultraviolet rays into the sealed reaction container 1. Figure 2 As shown, the ultraviolet light source 2 is arranged outside the sealed reaction container 1, and the sealed reaction container 1 and the cover plate 3 are made of opaque material.

[0055] The tests of the above embodiments further prove that the present invention provides a method and device for dehydrogenating the surface of granular silicon. The method and device of the present invention can remove hydrogen atoms on the surface of granular silicon, and the removal rate reaches 80% or more. Compared with conventional methods, the present invention has lower cost, simpler operation, shorter processing time and less energy consumption, and can process more granular silicon at the same time, thereby having higher commercial value and promotion value.

[0056] Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for dehydrogenating the surface of granular silicon, characterized in that: The following steps are involved: S1: A granular silicon surface dehydrogenation device is provided, the surface dehydrogenation device comprising a sealed reaction container (1), a cover plate (3), an ultraviolet light source (2) and an ozone generator (4), the cover plate (3) being movably arranged on the top of the sealed reaction container (1), the ozone generator (4) being connected to the inside of the sealed reaction container (1) via a connecting pipe (5), the ultraviolet light source (2) being used to provide ultraviolet light into the sealed reaction container (1), and the granular silicon to be surface dehydrogenated is laid on the bottom of the sealed reaction container (1); S2: turning on the ozone generator (4) to allow ozone gas to continuously flow into the sealed reaction container (1), and at the same time turning on the ultraviolet light source (2) to irradiate the surface of the silicon granules with ultraviolet light. After the irradiation is completed, turning off the ultraviolet light source (2), taking out the silicon granules, and completing the surface dehydrogenation; In the step S1, the granular silicon is laid in multiple layers on the bottom of the sealed reaction container (1) in a stacked manner, and the height of the granular silicon is lower than the ultraviolet light source (2); The flow rate of the ozone generator (4) is 2-10 g / h, the power of the ultraviolet light source (2) is 50-100 W, and the irradiation time is 30-90 minutes.

2. The method for dehydrogenating the surface of granular silicon according to claim 1, characterized in that: In the step S2, the flow rate of the ozone generator (4) is 3-5 g / h, the power of the ultraviolet light source (2) is 60-90 W, and the irradiation time is 50-70 minutes.

3. The method for dehydrogenating the surface of granular silicon according to claim 1, characterized in that: In the step S2, the flow rate of the ozone generator (4) is 4 g / h, the power of the ultraviolet light source (2) is 80 W, and the irradiation time is 60 minutes.

4. The method for dehydrogenating the surface of granular silicon according to claim 1, characterized in that: The reaction process of step S2 is as follows: O3+hν→O+O2; O+Si-H→Si+H2O.

5. The method for dehydrogenating the surface of granular silicon according to claim 1, characterized in that: The ultraviolet light source (2) is arranged outside the sealed reaction container (1), and the sealed reaction container (1) and the cover plate (3) are made of transparent material.

6. The method for dehydrogenating the surface of granular silicon according to claim 1, characterized in that: The ultraviolet light source (2) is arranged inside the sealed reaction container (1), and the ultraviolet light source (2) is fixed to the bottom of the cover plate (3); the sealed reaction container (1) and the cover plate (3) are made of opaque material.

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