Charging method of silicon material and single-crystal preparation method

Abstract

Disclosed are a charging method of a silicon material and a single-crystal preparation method. Said charging method comprises: spreading a first material layer in a crucible; and spreading a second material layer, the second material layer being arranged on the surface of the first material layer facing away from the bottom of the crucible, such that the second material layer covers the first material layer during a vacuumizing process. Also disclosed is the single-crystal preparation method using said charging method, the single-crystal preparation method comprising: covering a crucible with a crucible cover so as to form a sealed crucible body, vacuumizing the sealed crucible body, hoisting the sealed crucible body into a single crystal furnace, and performing pressure relief on the sealed crucible body. Said charging method can solve the problem of lacking reasonable crucible-charging steps during single crystal preparation. The single-crystal preparation method can solve the problem of existing material melting processes affecting the growth of single crystals during single crystal preparation, thereby improving the probability of the isodiametric length of single crystals being greater than 1000 mm.

Description

A method for charging silicon material and a method for preparing single crystal Technical Field

[0001] The present application belongs to the technical field of single crystal growth, and specifically relates to a method for charging silicon material used for native polycrystalline silicon powder in a Czochralski single crystal furnace and a method for preparing single crystals. Background Art

[0002] Native polysilicon powder refers to the by-product produced during the production of granular materials using the fluidized bed method. The silicon powder generation process mainly includes: using a fluidized bed process, using silane or chlorosilane as the silicon raw material gas, and using hydrogen as the carrier gas, so that the silane or chlorosilane enters the fluidized bed with polycrystalline silicon seed crystals as fluidized particles, and is cracked and deposited on the seed crystals, thereby obtaining granular polysilicon; during the reaction process, the silane gas rapidly decomposes after entering the fluidized bed, some of them undergo heterogeneous reactions and are deposited on the surface of the silicon particles, and another part of them undergoes homogeneous reactions to generate gas-phase micronuclei. The gas-phase micronuclei are generated through a series of polymerization nucleus growth processes. During the polymerization process, the generated silicon powder adheres to the surface of the silicon particles and becomes part of the silicon product.

[0003] The physical and chemical properties of silicon powder mainly include: the particle size of native polycrystalline silicon powder is small, which affects its use in CZ single crystal pulling furnaces for single crystals; the purity of native polycrystalline silicon powder is at the ppm level, and it contains some amorphous silicon and other impurities, which affects the single crystal growth process of the CZ method and easily causes breakage. At present, there is still a lack of application of native polycrystalline silicon powder in CZ single crystal pulling furnaces for single crystal pulling. Technical issues

[0004] The present application provides a method for loading silicon material to solve the problem of lack of a reasonable crucible loading process when pulling single crystals in a single crystal furnace; another purpose of the present application is to provide a method for preparing single crystals to solve the problem that the current chemical material process affects the single crystal growth process during single crystal preparation. Technical Solutions

[0005] In a first aspect, a method for charging silicon material into a crucible is provided, comprising:

[0006] Laying a first material layer in the crucible;

[0007] Laying a second material layer, the second material layer is arranged on a side of the first material layer away from the bottom of the crucible, so that during the vacuuming process, the second material layer covers the first material layer.

[0008] In some embodiments, along the first direction of the crucible, the crucible has a height h1, the silicon material of the first material layer has a first thickness d1, satisfying: d1≤4 / 5h1; and / or, along the first direction of the crucible, the second material layer has a second thickness d2, satisfying: d2≥40mm.

[0009] In some embodiments, the first material layer has a first particle size D1, and the second material layer has a second particle size D2, satisfying: D1 < D2; wherein the first particle size D1 ranges from 0.1 μm to 1000 μm; and / or the second particle size D2 ranges from 1 mm to 3 mm.

[0010] In some embodiments, the following steps are also included: laying a third material layer, the third material layer covering the second material layer; the third material layer has a third particle size D3, satisfying: D2<D3; wherein the value range of the third particle size D3 is 10mm~70mm.

[0011] In some embodiments, along the first direction of the crucible, until the third material layer fills the crucible, the third material layer has a maximum thickness d4 that is higher than the height h1 of the crucible, satisfying: d4 < 150 mm; and / or, along the first direction of the crucible, the first material layer has a first thickness d1, the second material layer has a second thickness d2, and the third material layer has a third thickness d3, satisfying: d1 > d2 > d3.

[0012] In some embodiments, d1+d2+d3≥h1 is satisfied.

[0013] In a second aspect, an embodiment of the present application further provides a method for preparing a single crystal, using the silicon material charging method described above. The method for preparing the single crystal includes:

[0014] The crucible is sealed with a lid to form a closed crucible body, and the closed crucible body is evacuated;

[0015] Hoist the crucible into the single crystal furnace to relieve the pressure of the single crystal furnace.

[0016] In some embodiments, the vacuuming time is 2 minutes to 5 minutes; and / or, the final vacuuming pressure is -0.08 MPa to 0.1 MPa; and / or, the pressure relief time is 2 minutes to 5 minutes.

[0017] In some embodiments, the single crystal furnace includes a valve and a pressure gauge, and after the pressure of the sealed crucible is released, the following steps are further included:

[0018] Remove the lid of the pot;

[0019] Set the initial opening value of the valve to 0%;

[0020] Make the pressure gauge value change less than 1 torr and the valve opening 5% to 15%;

[0021] The pressure of the single crystal furnace is stabilized, and the leak detection rate is obtained after leak detection of the single crystal furnace. The pressure of the single crystal furnace is set to be less than or equal to the preset pressure value to complete vacuuming.

[0022] In some embodiments, the preset pressure value ranges from 40 mtorr to 60 mtorr; and / or the leak detection rate is less than or equal to 120 mtorr / h to 150 mtorr / h.

[0023] In some embodiments, the single crystal furnace includes a first heater and a second heater; and after vacuuming, further includes:

[0024] Assume that the power of the first heater is 80 kW to 100 kW, the power of the second heater is 50 kW to 70 kW, the pressure in the single crystal furnace is 10 torr to 15 torr, and argon gas is introduced into the single crystal furnace at a flow rate of 40 slpm to 50 slpm; set the crucible to 0.5 to 1.5 revolutions until the silicon material is completely melted into liquid;

[0025] The power of the first heater is set to 60 kW to 80 kW, the power of the second heater is set to 10 kW to 20 kW, the pressure in the single crystal furnace is set to 4 Torr to 7 Torr, and the volatilization process is performed.

[0026] In some embodiments, after the volatilization process, silicon material having a third particle size D3 is added.

[0027] In some embodiments, after the volatilization process and before re-adding the silicon material having the third particle size D3, the method further includes:

[0028] The liquid is cooled so that the seed crystals with fine crystals come into contact with the liquid surface to form a crystallization surface for the first slag sticking.

[0029] In some embodiments, cooling the liquid so that the seed crystal with fine crystals contacts the liquid surface to form a crystallization surface comprises the following steps:

[0030] Assume that the power of the first heater is 50kw to 70kw to cool the liquid;

[0031] Set the crystal rotation speed to 1rpm~2rpm, set the crucible rotation speed to 2rpm~5rpm, lift the end of the fine crystal to the liquid surface by 100mm~150mm and then take it out to carry out the first slag sticking.

[0032] In some embodiments, after re-adding the silicon material having the third particle size D3, the method further includes:

[0033] The silicon material with the third particle size D3 after re-injection is melted. When 1kg to 2kg of silicon material remains, the seed crystal with fine crystals adheres to the remaining silicon material and picks up floating impurities on the liquid surface to perform a second slag sticking. Beneficial effects

[0034] Compared with the prior art, the present application provides a method for loading silicon material into a crucible, comprising: laying a first material layer in the crucible; laying a second material layer, the second material layer being arranged on a side of the first material layer facing away from the bottom of the crucible, so that during the vacuuming process, the second material layer covers the first material layer; the present application provides a method for loading silicon material, by laying the first material layer in the crucible and covering the second material layer on a side of the first material layer facing away from the bottom of the crucible, so that during the vacuuming process, the first material layer is covered by the second material layer, so that the first material layer is not blown out of the crucible, thereby realizing a reasonable loading step. The silicon material loading method provided by the present application can solve the problem of lack of a reasonable crucible loading step when preparing single crystals in a single crystal furnace.

[0035] It can be understood that, compared with the prior art, the single crystal preparation method provided in the embodiment of the present application adopts a silicon material loading method as described above, and the single crystal preparation method includes: covering the crucible with a pot lid to form a closed crucible body, and evacuating the closed crucible body; hoisting the closed crucible body into the single crystal furnace, and depressurizing the closed crucible body; through the steps of evacuating the closed crucible body and depressurizing the closed crucible body, favorable conditions are provided for the single crystal pulling process, so that the silicon material is not extracted during the single crystal preparation. The single crystal preparation method can solve the problem that the current chemical material process affects the single crystal growth process during the single crystal preparation; the single crystal preparation method has all the technical features and beneficial effects of the above-mentioned silicon material loading method, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG1 is a schematic flow chart of the method for preparing a single crystal of the present application;

[0037] FIG2 is a schematic structural diagram of a crucible and a lid in an embodiment of the present application, wherein the lid moves downward until loading is completed;

[0038] FIG3 is a schematic structural diagram of a crucible and a lid in another embodiment of the present application, in which the lid moves downward until loading is completed;

[0039] FIG4 is a schematic diagram showing that the third material layer is higher than the crucible;

[0040] Reference numerals: 100 - crucible, 210 - first material layer, 220 - second material layer, 230 - third material layer, 300 - pot cover.

[0041] Implementation Methods of the Application

[0042] This application provides a method for charging silicon material and a method for preparing a single crystal. To make the purpose, technical solution, and effects of this application more clear and explicit, the application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are only intended to explain this application and are not intended to limit this application.

[0043] 1 to 3 , a method for charging silicon material into a crucible 100 is provided, comprising:

[0044] Laying the first material layer 210 in the crucible 100;

[0045] A second material layer 220 is laid, and the second material layer 220 is arranged on the side of the first material layer 210 away from the bottom of the crucible 100, so that during the vacuuming process, the second material layer 220 covers the first material layer 210; that is, by laying the second material layer 220 on the side of the first material layer 210 away from the bottom of the crucible 100, the first material layer 210 is capped by the second material layer 220, that is, the second material layer 220 completely covers the first material layer 210, so that the first material layer 210 is not blown out in the crucible 100.

[0046] The single crystal preparation method provided in the present application is achieved by laying a first material layer 210 in the crucible 100 and arranging a second material layer 220 on the side of the first material layer 210 away from the bottom of the crucible 100, so that during the vacuuming process, the second material layer 220 covers the first material layer 210. Therefore, by filling the crucible 100 with silicon material, the silicon material includes the first material layer 210 and the second material layer 220, so that the second material layer 220 completely covers the first material layer 210, and the step of reasonably loading the crucible 100 is achieved; the silicon material loading method can solve the problem of lack of a reasonable crucible loading step when preparing single crystals in a single crystal furnace.

[0047] In some embodiments of the present application, along the first direction X of the crucible 100 , the crucible 100 has a height h1 , and the first material layer 210 has a first thickness d1 , satisfying: d1 ≤ 4 / 5 h1 .

[0048] In a further embodiment, h1 and d1 further satisfy: d1≤3 / 4h1.

[0049] Therefore, by limiting the relative proportional relationship between the first thickness d1 of the first material layer 210 and the height h1 of the crucible 100 , the first material layer 210 can be reasonably disposed inside the crucible 100 .

[0050] In some embodiments, along the first direction X of the crucible 100 , the second material layer 220 has a second thickness d2 , satisfying: d2 ≥ 40 mm. By limiting the absolute range of the second thickness d2 of the second material layer 220 , a reasonable thickness range design of the second material layer 220 inside the crucible 100 is achieved.

[0051] In some embodiments, the silicon material of the first material layer 210 has a first particle size D1 , and the silicon material of the second material layer 220 has a second particle size D2 , satisfying: D1 < D2 . In this embodiment, the first material layer 210 is more compact than the second material layer 220 .

[0052] In the above embodiment, it should be noted that the material of the first material layer 210 is virgin polycrystalline silicon powder, and the first particle size D1 ranges from 0.1 μm to 1000 μm; the material of the second material layer 220 is silicon powder, and the second particle size D2 ranges from 1 mm to 3 mm. In some embodiments, the first particle size D1 ranges from any one of 0.1 μm, 1 μm, 10 μm, 100 μm, 500 μm, and 1000 μm, or any combination thereof, and the second particle size D2 ranges from any one of 1 mm, 1.5 mm, 2 mm, 2.5 mm, and 3 mm, or any combination thereof. By limiting the first particle size D1 of the first material layer 210 and the second particle size D2 of the second material layer 220, it is convenient to achieve the purpose of rationally charging the first material layer 210 and / or the second material layer 220.

[0053] In some other embodiments of the present application, the difference from the above embodiment is that after the second material layer 220 is covered on the first material layer 210, the silicon material loading method further includes:

[0054] The third material layer 230 is laid, and the third material layer 230 covers the second material layer 220, that is, the third material layer 230 seals the second material layer 220; wherein, the silicon material of the third material layer 230 has a third particle size D3, satisfying: D2<D3; by setting the second particle size D2 to be smaller than the third particle size D3, the design purpose of making the second material layer 220 more compact relative to the third material layer 230 is achieved.

[0055] Based on the above embodiments, the loaded silicon material includes a first material layer 210, a second material layer 220 and a third material layer 230; in some embodiments, the material of the third material layer 230 is silicon material, and the value range of the third particle size D3 is 10 mm to 70 mm; in some embodiments, the third particle size D3 is: any one of 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm or a range value composed of any two of them, thereby achieving the purpose of reasonable loading of the third material layer 230.

[0056] In some embodiments, as shown in Figures 2 and 3, in order to fill the crucible 100 with as much raw material as possible, the third material layer 230 is loaded along the first direction X of the crucible 100 until the crucible 100 is filled with the third material layer 230. The third material layer 230 has a maximum thickness d4 that is higher than the height h1 of the crucible 100. That is, the maximum thickness d4 of the silicon material as the raw material that allows the third material layer 230 to exceed the crucible 100 satisfies: d4 < 150 mm; in some embodiments, d4 is a range value composed of any one or any two of 120 mm, 125 mm, 130 mm, 135 mm, 140 mm, and 145 mm, thereby limiting the maximum extent to which the third material layer 230 can exceed the crucible 100, preventing the third material layer 230 from exceeding the crucible 100 by exceeding the maximum limit, and ensuring reasonable loading of the third material layer 230.

[0057] In some embodiments, along the first direction X of the crucible 100, the second material layer 220 has a second thickness d2, and the third material layer 230 has a third thickness d3, satisfying the following relationship: d1>d2>d3; that is, the second thickness d2 of the second material layer 220 is lower than the first thickness d1 of the first material layer 210, and the third thickness d3 of the third material layer 230 is lower than the second thickness d2 of the second material layer 220. In other words, the thicknesses of the first material layer 210, the second material layer 220, and the third material layer 230 along the first direction X are designed to gradually decrease.

[0058] In some embodiments, as shown in FIG2 , d1+d2+d3>h1; that is, by making the sum of the first thickness d1 of the first material layer 210, the second thickness d2 of the second material layer 220, and the third thickness d3 of the third material layer 230 greater than the height of the crucible 100, that is, the top of the third material layer 230 exceeds the height of the crucible 100, the crucible 100 is filled with raw materials as much as possible.

[0059] In some embodiments, as shown in FIG3 , d1+d2+d3=h1; that is, the sum of the first thickness d1 of the first material layer 210, the second thickness d2 of the second material layer 220, and the third thickness d3 of the third material layer 230 is equal to the height of the crucible 100. The condition of d1+d2+d3=h1 is set to meet the situation that the crucible 100 is just filled with raw materials and does not need to be filled more. It only needs to meet the actual requirements of the silicon material loading method of the present application. The specific size also needs to be set according to the actual raw material requirements and the subsequent single crystal preparation process requirements.

[0060] The above-mentioned silicon material loading method of the present application realizes a reasonable loading step by laying the first material layer 210 in the crucible 100 and covering the second material layer 220 on the first material layer 210. The loading step is suitable for the crucible loading step during the preparation of single crystals, thereby solving the problem of lack of a reasonable crucible loading step during the preparation of single crystals in a single crystal furnace.

[0061] The present application also provides a method for preparing a single crystal, using the silicon material charging method described above. The method for preparing the single crystal includes:

[0062] Step 100: Cover the crucible 100 with the pot cover 300 to form a sealed crucible body, and evacuate the sealed crucible body;

[0063] Step 200: hoisting the sealed crucible into the single crystal furnace and releasing the pressure of the sealed crucible.

[0064] In step 100 and step 200, the vacuuming time is 2 minutes to 5 minutes; and / or, the final vacuuming pressure is -0.08 MPa to 0.1 MPa; and / or, the pressure relief time is 2 minutes to 5 minutes.

[0065] In step 100, negative pressure is applied to the pot cover 300. In order to prevent the silicon powder in the crucible 100 from being extracted after loading, the changes in the pressure gauge are observed during the vacuuming process. The vacuuming process is carried out slowly by slowly adjusting the vacuuming valve. The vacuuming time is controlled within 2 to 5 minutes, and the vacuuming speed is controlled at the same time; and / or, the pressure is controlled between -0.08 MPa and 0.1 MPa. After there is no fluctuation on the dial of the pressure gauge, the vacuuming valve is closed. In some embodiments, the vacuuming time is a range value consisting of any one of 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min, and 5 min, or any two of the range values; the pressure is a range value consisting of any one of -0.08 MPa, -0.06 MPa, -0.4 MPa, -0.02 MPa, 0 MPa, 0.02 MPa, 0.04 MPa, 0.06 MPa, 0.08 MPa, and 0.1 MPa, or any two of the range values.

[0066] In step 200, the sealed crucible is hoisted into the single crystal furnace, and then the pressure relief valve is slowly opened to release air and relieve pressure. The pressure relief process needs to be carried out slowly, and the pressure relief time value of the sealed crucible is any one of 2min, 2.5min, 3min, 3.5min, 4min, 4.5min, 5mina or a range value composed of any two of them.

[0067] The single crystal preparation method of the present application is to seal the crucible with a pot lid to form a closed crucible body, thereby evacuating the closed crucible body; hoisting the sealed crucible body into the single crystal furnace to relieve the pressure on the closed crucible body; the vacuuming and pressure relief processes provide conditions for the single crystal pulling process.

[0068] The single crystal furnace includes a valve and a pressure gauge. After the pressure of the sealed crucible is released, the process further includes step 300:

[0069] Step S310: removing the pot cover 300 and closing the single crystal furnace;

[0070] Step S320: setting the initial value of the valve opening to 0%;

[0071] Step S330: The pressure gauge value variation range is set to be less than 1 torr, and the valve opening range is set to 5% to 15%; wherein, the pressure gauge value variation range is set to be within the range of any one of 0.05 torr, 0.06 torr, 0.07 torr, 0.08 torr, and 0.09 torr, or any two of the ranges; and the valve opening range is set to be within the range of any one of 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, and 15%, or any two of the ranges.

[0072] In the embodiment of the present application, the valve is a throttle valve and the pressure gauge is a Torr gauge.

[0073] In steps S310 to S330, the process conditions for vacuuming and depressurizing the closed crucible are set by limiting the valve opening and the range of change of the pressure gauge value, so that the silicon material is not extracted during the single crystal preparation process.

[0074] Step S340: Stabilize the pressure of the single crystal furnace, obtain the leak detection rate after leak detection of the single crystal furnace, set the pressure of the single crystal furnace to be less than or equal to the preset pressure value to complete vacuuming; repeat the previous step, i.e., step S330, each time adding an opening of 5% to 15% until the opening is 100%, so as to stabilize the pressure of the single crystal furnace.

[0075] In step S340, in some embodiments, for the single crystal furnace, the preset pressure value is in the range of 40mtorr to 60mtorr, and / or the leak detection rate is less than or equal to 120mtorr / h to 150mtorr / h. In some embodiments, the preset pressure value is in the range of any one of 40mtorr, 45mtorr, 50mtorr, 55mtorr, and 60mtorr, or any two thereof. In some embodiments, the leak detection rate is in the range of any one of 120mtorr / h, 125mtorr / h, 130mtorr / h, 135mtorr / h, 140mtorr / h, 145mtorr / h, and 150mtorr / h, or any two thereof. In step S340, by limiting the preset pressure value and / or the leak detection rate, a vacuum process is achieved during the single crystal preparation process, thereby preventing the silicon material from being extracted from the crucible 100.

[0076] In some embodiments, the single crystal furnace includes a first heater and a second heater, the first heater being a main heater and the second heater being a bottom heater; after evacuation, the single crystal preparation method provided in the present application further includes:

[0077] Step 400: Assume that the power of the first heater is 80 kW to 100 kW, the power of the second heater is 50 kW to 70 kW, the pressure in the single crystal furnace is 10 torr to 15 torr, and argon is introduced into the single crystal furnace with a flow rate of 40 slpm to 50 slpm; rotate the crucible 0.5 to 1.5 times, specifically 1 time, until the silicon material is completely melted into liquid; Step 400 is the step of melting the material.

[0078] In this step 400, the power value of the first heater is any one of 80kW, 85kW, 90kW, 95kW, and 100kW, or a range value consisting of any two of them; the power value of the second heater is any one of 50kW, 55kW, 60kW, 65kW, and 70kW, or a range value consisting of any two of them; the pressure in the single crystal furnace is any one of 10torr, 11torr, 12torr, 13torr, 14torr, and 15torr, or a range value consisting of any two of them; the flow rate of argon gas is any one of 40slpm, 41slpm, 42slpm, 43slpm, 44slpm, 45slpm, 46slpm, 47slpm, 48slpm, 49slpm, and 50slpm, or a range value consisting of any two of them.

[0079] The vacuuming process in step 300 and the melting step in step 400 can provide effective conditions for the Czochralski single crystal in the single crystal preparation method of the present application by melting the material at low power and extending the melting time.

[0080] Step 500: After the silicon material is completely melted into liquid, the power of the first heater is set to 60 kW to 80 kW, the power of the second heater is set to 10 kW to 20 kW, and the pressure in the single crystal furnace is set to 4 Torr to 7 Torr, and a volatilization process is performed.

[0081] In this step 500 , the volatilization time is 1 hour, and the high-temperature volatilization is continuously performed.

[0082] In step 500, in some embodiments, the power of the first heater is any one of 60 kW, 65 kW, 70 kW, 75 kW, and 80 kW, or any two of them; the power of the second heater is any one of 10 kW, 11 kW, 12 kW, 13 kW, 14 kW, 15 kW, 16 kW, 17 kW, 18 kW, 19 kW, and 20 kW, or any two of them; and the pressure in the single crystal furnace is any one of 4 Torr, 4.5 Torr, 5 Torr, 5.5 Torr, 6 Torr, 6.5 Torr, and 7 Torr, or any two of them. By limiting the vacuuming and performing the volatilization process after the melting process, the insoluble impurities or insoluble impurities can be removed after the volatilization process is completed, thereby achieving the technical effect of optimizing the material processing process. The volatilization process is used to provide support conditions for single crystal pulling after the melting process.

[0083] After high-temperature volatilization according to step 500, the single crystal preparation method of the present application further includes:

[0084] Step 600: Cooling the liquid so that the seed crystal with fine crystals contacts the liquid surface to form a crystallization surface, thereby performing the first slag sticking.

[0085] And wherein, in step 600, it also includes:

[0086] Step 610: Set the power of the first heater to 50kw~70kw to cool the liquid; in this step 610, the power value of the first heater is any one of 50kw, 55kw, 60kw, 65kw, 70kw or a range of any two of them.

[0087] In step 610 , to cool the liquid, the power of the second heater is 0 kW.

[0088] Step 620: Set the crystal rotation speed to 1 rpm to 2 rpm, set the crucible rotation speed to 2 rpm to 5 rpm, raise the distance between the end of the fine crystal and the liquid surface by 100 mm to 150 mm, and then take it out to perform the first slag sticking.

[0089] In step 600 and step 610, the power of the first heater, the power of the second heater, the crystal rotation, the crucible rotation, and the distance from the end of the fine crystal to the liquid surface are all set within a reasonable range to complete the first slag sticking, thereby removing insoluble impurities or insoluble impurities in the loading and chemical processing process.

[0090] In this step 620, the rpm of the crystal rotation is any one of 1rpm, 1.1rpm, 1.2rpm, 1.3rpm, 1.4rpm, 1.5rpm, 1.6rpm, 1.7rpm, 1.8rpm, 1.9rpm, and 2rpm, or a range of values ​​consisting of any two of them, and the number of rotations of the crucible rotation is any one of 2rpm, 2.5rpm, 3rpm, 3.5rpm, 4rpm, 4.5rpm, and 5rpm, or a range of values ​​consisting of any two of them.

[0091] After the first slag adhesion in step 600 and step 620, the single crystal preparation method of the present application further includes:

[0092] Step 700: Re-adding silicon material having a third particle size D3.

[0093] In this step 700, by re-dosing silicon material with a third particle size D3, the amount of silicon material put into production is increased to the greatest extent. The re-dosing process is equivalent to providing process support for the entire process of loading, chemical processing, re-dosing and chemical processing for single crystal preparation.

[0094] After step 700, the silicon material is a silicon material having a third particle size D3. After step 700, the method further includes:

[0095] Step 800: The silicon material with the third particle size D3 after re-injection is melted. When 1kg to 2kg of silicon material remains, the seed crystal with fine crystals adheres to the remaining silicon material and dips into the liquid to remove floating impurities, thereby performing a second slag binding.

[0096] It should be noted that in step 800, after the silicon material is re-added, the insoluble impurities or poorly soluble impurities in the re-added silicon material are removed by performing the steps of chemical treatment and second slag removal on the re-added silicon material.

[0097] Step 900: Execute the automatic crystal pulling process and proceed to the remaining crystal pulling steps.

[0098] In the above steps 100 to 800 of the present application, according to the above steps 100 to 500, the material is successively hoisted, vacuumed, melted, and volatilized to perform the material processing; according to step 600, the material after the material processing is subjected to the first slag sticking; after the silicon material with the third particle size D3 is re-added according to step 700, the step of processing the re-added silicon material with the third particle size D3 is also included, which is equivalent to first re-adding the silicon material with the third particle size D3 according to the above-mentioned silicon material loading method, and then according to the above steps 100 to 500, the material is successively hoisted, vacuumed, melted, and volatilized to perform the material processing, and finally the silicon material with the third particle size D3 is re-added according to step 700, and the material after the material processing is subjected to the second slag sticking according to step 800.

[0099] The present application provides a method for loading silicon material and a method for preparing single crystals, which can solve the problem of lack of a reasonable crucible loading process and material chemical process when pulling single crystals in a single crystal furnace, and can solve the problem of the current material chemical process affecting the single crystal growth process during single crystal preparation, thereby increasing the probability of the single crystal equal diameter length being greater than 1000 mm by a certain percentage.

[0100] Therefore, the single crystal preparation method provided in the present application adopts the above-mentioned silicon material loading method to load silicon material, and the single crystal preparation method includes: covering the crucible 100 with a pot lid 300 to form a closed crucible body, and evacuating the closed crucible body; depressurizing the closed crucible body; closing the single crystal furnace after removing the closed crucible body to evacuate, thereby improving the vacuuming process, so that the silicon material can be successfully melted in the single crystal furnace, and through the optimization of the melting process, low power conditions are adopted for melting, the melting time is extended, and the melting is completed and volatilized to remove insoluble impurities; by re-adding silicon material with a third particle size D3 and melting the material, the loading and melting can be repeated, thereby increasing the amount of silicon material used as a raw material for single crystal preparation; before and after re-adding silicon material with a third particle size D3, the infusible impurities or insoluble impurities are removed by the first and second slag sticking, so that the silicon material is used as a raw material for vertical pulling single crystals to produce single crystal silicon rods.

[0101] The single crystal preparation method provided herein achieves successful melting of silicon material within a single crystal furnace by improving the silicon material loading method and vacuuming process. By optimizing the melting process, low-power melting is employed, extending the melting time, achieving complete volatilization after melting, and removing insoluble impurities. Furthermore, a double slag removal process removes infusible or insoluble impurities, enabling the use of silicon powder as a raw material in the CZ Czochralski method for producing single crystal silicon rods. Consequently, this single crystal preparation method can address the issue of current melting processes affecting the single crystal growth process during single crystal preparation.

[0102] The above is a detailed introduction to a silicon material loading method and a single crystal preparation method provided in the embodiments of the present application. Specific examples are used in this application to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for charging silicon material, for charging silicon material into a crucible (100), wherein: include: Laying a first material layer (210) in the crucible (100); A second material layer (220) is laid, wherein the second material layer (220) is arranged on a side of the first material layer (210) facing away from the bottom of the crucible (100), so that during the vacuuming process, the second material layer (220) covers the first material layer (210).

2. A method for charging silicon material according to claim 1, wherein: Along a first direction (X) of the crucible (100), the crucible (100) has a height h1, and the first material layer (210) has a first thickness d1, satisfying: d1≤4 / 5h1; and / or, Along the first direction (X) of the crucible (100), the second material layer (220) has a second thickness d2, satisfying: d2 ≥ 40 mm.

3. A method for charging silicon material according to claim 1, wherein: The silicon material of the first material layer (210) has a first particle size D1, and the silicon material of the second material layer (220) has a second particle size D2, satisfying: D1<D2; wherein, The first particle size D1 has a value range of 0.1 μm to 1000 μm; and / or, The second particle diameter D2 has a value range of 1 mm to 3 mm.

4. A method for charging silicon material according to claim 1, wherein: The following steps are also included: Laying a third material layer (230), wherein the third material layer (230) covers the second material layer (220); The silicon material of the third material layer (230) has a third particle size D3, satisfying: D2<D3; wherein, The third particle diameter D3 has a value range of 10 mm to 70 mm.

5. A method for charging silicon material according to claim 4, wherein: Along the first direction (X) of the crucible (100), until the third material layer (230) fills the crucible (100), the third material layer (230) has a maximum thickness d4 of a height h1 above the crucible (100), satisfying: d4 < 150 mm; and / or, Along the first direction (X) of the crucible (100), the first material layer (210) has a first thickness d1, the second material layer (220) has a second thickness d2, and the third material layer (230) has a third thickness d3, satisfying: d1>d2>d3.

6. A method for charging silicon material according to claim 5, wherein: Satisfies: d1+d2+d3≥h1.

7. A method for preparing a single crystal, wherein: Using the silicon material charging method according to any one of claims 1 to 6, the single crystal preparation method comprises: The pot cover (300) covers the crucible (100) to form a closed crucible body, and the closed crucible body is evacuated; The sealed crucible is hoisted into a single crystal furnace and the pressure of the sealed crucible is relieved.

8. The method for preparing a single crystal according to claim 7, wherein: The vacuuming time is 2 to 5 minutes; And / or, the final pressure of the vacuum pumping is -0.08MPa to 0.1MPa; And / or, the pressure relief time is 2 minutes to 5 minutes.

9. The method for preparing a single crystal according to claim 7, wherein: The single crystal furnace comprises a valve and a pressure gauge, and after the pressure of the closed crucible is released, the following steps are further included: Removing the pot cover (300); Setting the initial opening value of the valve to 0%; The value change range of the pressure gauge is made less than 1 torr, and the opening of the valve is made 5% to 15%; The pressure of the single crystal furnace is stabilized, a leak detection rate is obtained after leak detection of the single crystal furnace, and the pressure of the single crystal furnace is set to be less than or equal to a preset pressure value to complete vacuuming.

10. The method for preparing a single crystal according to claim 9, wherein: The preset pressure value ranges from 40mtorr to 60mtorr; And / or, the leak detection rate is less than or equal to 120 mtorr / h to 150 mtorr / h.

11. The method for preparing a single crystal according to claim 9, wherein: The single crystal furnace comprises a first heater and a second heater; after vacuuming, it also comprises: Assume that the power of the first heater is 80kw-100kw, the power of the second heater is 50kw-70kw, the pressure in the single crystal furnace is 10torr-15torr, argon gas is introduced into the single crystal furnace, and the flow rate of the argon gas is 40slpm-50slpm; set the crucible to 0.5-1.5 turns until the silicon material is completely melted into liquid; The power of the first heater is set to be 60 kW to 80 kW, the power of the second heater is set to be 10 kW to 20 kW, the pressure in the single crystal furnace is set to be 4 torr to 7 torr, and a volatilization process is performed.

12. The method for preparing a single crystal according to claim 11, wherein: After the volatilization process, silicon material with a third particle size D3 is added again.

13. The method for preparing a single crystal according to claim 12, wherein: After the volatilization process and before re-adding the silicon material having the third particle size D3, the method further includes: The liquid is cooled down, and the seed crystals with fine crystals are brought into contact with the liquid surface of the liquid to form a crystallization surface, so as to carry out the first slag sticking.

14. The method for preparing a single crystal according to claim 13, wherein: The liquid is cooled to allow the seed crystal with fine crystals to contact the liquid surface of the liquid to form a crystallization surface, comprising the following steps: The power of the first heater is set to be 50 kW to 70 kW to cool the liquid; The crystal rotation speed is set to 1 rpm to 2 rpm, the crucible rotation speed is set to 2 rpm to 5 rpm, and the distance between the end of the fine crystal and the liquid surface is raised by 100 mm to 150 mm and then taken out to perform the first slag sticking.

15. The method for preparing a single crystal according to claim 13, wherein: After re-adding the silicon material having the third particle size D3, the method further comprises: The silicon material with the third particle size D3 after re-injection is melted, and when 1kg to 2kg of the silicon material remains, the seed crystal with fine crystals adheres to the remaining silicon material and dips the floating impurities on the liquid surface to carry out the second slag sticking.

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