Refeeding method of silicon crystal bar

Abstract

The invention relates to the technical field of preparation of silicon crystal bars, in particular to a re-feeding method of a silicon crystal bar. The re-feeding method of the silicon crystal bar comprises the steps that after preparation of one silicon crystal bar is completed, the position of a material carrying device is made to rise to 170-210 mm relative to a standard zero position, the lower end of the material carrying device is partially contained in a heating device, and the heating device is adopted to conduct preheating treatment on the material carrying device; and after the preheating treatment, repeated feeding is carried out on the material loading device for multiple times, and the position of the material loading device is lowered by 60-100 mm before each time of repeated feeding. According to the re-feeding method of the silicon crystal bar, through cooperation of the conditions, direct baking of the heating device on the straight wall and the upper edge of the material carrying device can be avoided, straight wall bulging and upper edge collapse of the material carrying device can be effectively reduced, the heating deviation of a heating area of the heating device on solid material blocks in the material carrying device can be reduced to a certain extent, and the service life of the material carrying device is prolonged. The material melting efficiency can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon crystal rod preparation, and in particular to a silicon crystal rod re-investment method. Background Art

[0002] The production of solar-grade Czochralski single crystal silicon adopts Czochralski single crystal furnace. The basic production process includes: loading, chemical processing, pulling single crystal, taking out rods, stopping the furnace, and cleaning the furnace. The raw material used in production is crystalline silicon, which is put into the quartz crucible of the single crystal furnace at one time or in batches; the quality of the crystal rods prepared by one-time input is poor. The current defects of batch input include: the heating time of the straight wall and upper edge of the crucible by the heater runs through the entire operation cycle of the single crystal furnace, which reduces the service life of the upper part of the straight wall of the crucible, and increases the rate of abnormal collapse and softening of the crucible. In severe cases, it may even cause the furnace to stop prematurely during the crystal pulling process, resulting in waste of production capacity.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] An object of the present invention is to provide a method for re-feeding silicon crystal rods to reduce the baking of the upper edge of the loading device and improve the material efficiency.

[0005] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0006] A silicon crystal rod re-investment method comprises the following steps:

[0007] After completing the preparation of a silicon crystal rod, the position of the loading device is raised to 170-210 mm relative to the standard zero position, and the lower end portion of the loading device is accommodated in the interior of the heating device, and the heating device is used to preheat the loading device; after the preheating treatment, the loading device is re-charged for multiple times, and before each re-charging, the position of the loading device is lowered by 60-100 mm.

[0008] In some embodiments, the standard zero position means that an upper port of the material loading device and an upper port of the annular heating area inside the heating device are located in the same plane.

[0009] In some implementation methods, the time between any two adjacent re-additions is 40 to 60 minutes.

[0010] In some embodiments, the mass of the re-added material each time is 15% to 25% of the mass of the remaining material in the loading device after the preheating treatment.

[0011] In some embodiments, the mass of the residual material in the loading device after the preheating treatment is 480-500 kg.

[0012] In some implementation methods, the number of times of re-adding is 4 to 7 times.

[0013] In some embodiments, the height of the loading device is 650-750 mm.

[0014] In some embodiments, the heating device includes a heat-insulating shell, a heater, and a displacement device, wherein the heater forms an annular heating zone inside the heat-insulating shell; and the displacement device is used to adjust the position of the loading device.

[0015] In some implementations, the height of the annular heating zone is 230-270 mm.

[0016] In some embodiments, the preheating treatment lasts for 10 to 30 minutes.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention optimizes the silicon crystal rod re-feeding method and coordinates the conditions of each step to avoid direct baking of the straight wall and the upper edge of the loading device by the heating device, which can effectively reduce the bulging of the straight wall and the collapse of the upper edge of the loading device, and can reduce the heating deviation of the solid material blocks in the loading device by the heating zone of the heating device to a certain extent, which can effectively improve the material efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the silicon crystal rod re-feeding device of the present invention.

[0021] Reference numerals:

[0022] 1-heating device, 101-insulating shell, 102-annular heating zone, 103-displacement device, 2-loading device. DETAILED DESCRIPTION

[0023] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0024] The present invention relates to a silicon crystal rod re-investment method, comprising the following steps:

[0025] After completing the preparation of a silicon crystal rod, the position of the loading device is raised to 170-210 mm relative to the standard zero position, and the lower end portion of the loading device is accommodated in the interior of the heating device, and the heating device is used to preheat the loading device; after the preheating treatment, the loading device is re-charged for multiple times, and before each re-charging, the position of the loading device is lowered by 60-100 mm.

[0026] The present invention optimizes the silicon crystal rod re-feeding method and, through the coordination of the above conditions, can avoid direct baking of the straight wall and the upper edge of the loading device by the heating device, can effectively reduce the bulging of the straight wall and the collapse of the upper edge of the loading device, and can reduce the heating deviation of the solid material blocks in the loading device by the heating zone of the heating device to a certain extent, which can effectively improve the material efficiency.

[0027] In some embodiments, the standard zero position means that the upper port of the material loading device and the upper port of the annular heating area inside the heating device are located in the same plane. The standard zero position is defined to better describe the relative position of the material loading device.

[0028] In some embodiments, the time between any two adjacent re-feeding is 40 to 60 minutes, such as 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes or 40 minutes, or any range between the two. The re-feeding method of the present invention can further reduce the interval time between two adjacent re-feeding, thereby improving the preparation efficiency.

[0029] In some embodiments, the mass of the re-added material each time is 15% to 25% of the mass of the remaining material in the loading device after the preheat treatment, for example, 15%, 16%, 17%, 18%, 19%, 20%, 18%, 21%, 22% or 25%, or any range value between the two.

[0030] In some embodiments, the mass of the residual material in the loading device after the preheat treatment is 480-500 kg, and the mass of the re-feeding each time is 75-120 kg, for example, 75 kg, 80 kg, 90 kg, 100 kg, 110 kg or 120 kg.

[0031] In some embodiments, the number of re-feeding is N times, N is greater than 3, and from the first to the Nth re-feeding process, the height of the loading device drops each time in a decreasing trend. Before the first re-feeding, the position of the loading device drops by 100 mm, and before the Nth re-feeding, the position of the loading device drops by 60 mm.

[0032] In some embodiments, the number of re-feeding is 4 to 7 times, for example 4 times, 5 times, 6 times or 7 times.

[0033] In some embodiments, the height of the loading device is 650-750 mm, for example, 650 mm, 660 mm, 670 mm, 680 mm, 690 mm, 700 mm, 710 mm, 720 mm, 730 mm or 750 mm, etc. The loading device has a suitable height to ensure that the material has a better material processing effect, reduce the baking of the upper edge of the loading device by the heating device, and improve its service life.

[0034] In some embodiments, the heating device includes a heat-insulating shell, a heater, and a displacement device, wherein the heater forms an annular heating zone inside the heat-insulating shell; and the displacement device is used to adjust the position of the loading device.

[0035] In some embodiments, the height of the annular heating zone is 230-270 mm, such as 230 mm, 230 mm, 250 mm, 260 mm, 270 mm, etc. The annular heating zone of the present invention has a suitable height, thereby ensuring the heating effect of the material in the loading device and ensuring the material efficiency.

[0036] In some embodiments, the preheating treatment time is 10 to 30 minutes, for example, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, etc.

[0037] In some embodiments, during the actual crystal pulling process, the position of the loading device is in a constantly changing process. For example, during the equal diameter process, which is the process of converting the molten silicon liquid in the furnace into a solid single crystal, the loading device is in a slowly rising process as the length of the crystal rod increases under the relatively fixed state of the solid-liquid growth interface. After the crystal rod equal diameter length of 4000 to 4500 mm (which needs to be considered in combination with the crystal rod size and process parameters) is produced, the loading device rises 200 to 240 mm relative to the physical zero position when the crystal rod is finished. When the crystal rod is finished or the wire is broken and pulled out, in order to ensure that the crystal rod is out of the liquid surface, the crucible automatically drops 30 to 50 mm, so that the position of the loading device rises 170 to 210 mm relative to the physical zero position.

[0038] In a preferred embodiment, the method for re-investing silicon crystal rods comprises the following steps:

[0039] (a) After the end of a silicon crystal rod, the position of the loading device is raised to 170-210 mm relative to the standard zero position, and the position of the loading device remains unchanged as a preheating crucible position. At this time, the vertical distance between the plane where the upper edge of the loading device is located and the plane where the upper edge of the annular heating zone inside the heating device is located is 185-225 mm, and the lower end of the loading device is accommodated in the interior of the heating device. The height of the loading device is 650-750 mm, and the height of the annular heating zone is 230-270 mm. The heating device is used to preheat the loading device, and the preheating time is 10-30 minutes. The annular heating zone is heated, and the heating power used by the heater is 70-85 kW.

[0040] The loading device of the present invention has the above-mentioned suitable position, and because the silicon crystal rod has just finished the finishing state, the temperature of the silicon liquid in the furnace is low. During the preheating treatment, the heating area of ​​the heating device can avoid baking the straight wall of the crucible, but instead heats the molten silicon, which can achieve rapid heating of the molten silicon and further improve the efficiency of heat utilization.

[0041] (b) After the preheating treatment, the mass of the residual material in the loading device is 480-500 kg. The loading device is re-charged 5 times, each time with 90-110 kg. Before the first re-charge, the position of the loading device is lowered by 100 mm. After the material blocks are added to the loading device, they are mainly concentrated in the lower part of the charging device. At this time, the distance between the material blocks and the annular heating zone is appropriate, which can further improve the heat utilization rate of the heating device for melting the material. After the melting of the material blocks is completed, the second to fifth re-charges are carried out. Before each re-charge, the position of the loading device is lowered by 80 mm. The interval time between any two re-charges is 40-60 minutes.

[0042] The following is further explained in conjunction with specific embodiments.

[0043] The silicon crystal rod re-investment device involved in each embodiment, such as Figure 1 As shown, it includes a heating device 1, a loading device 2 and a feeding device (not shown), the heating device 1 includes a heat-insulating shell 101, a heater and a displacement device 103, the heater forms an annular heating zone 102 inside the heat-insulating shell 101; the displacement device 103 is used to adjust the position of the loading device 2; the feeding device is used to carry out re-feeding.

[0044] Example 1

[0045] A silicon crystal rod re-investment method comprises the following steps:

[0046] After the finishing of a silicon crystal rod is completed, the position of the loading device 2 is raised to 200mm relative to the standard zero position. The standard zero position means that the upper port of the loading device 2 and the upper port of the annular heating zone 102 inside the heating device 1 are located in the same plane; the position of the loading device 2 remains unchanged as a preheating crucible position, and the lower end portion of the loading device 2 is accommodated inside the heating device 1. The height of the loading device 2 is 700mm, and the height of the annular heating zone 102 is 250mm. The heating device 1 is used to preheat the loading device 2. The preheating time is 15min. The annular heating zone 102 is heated, and the heating power used by the heater is 85KW.

[0047] After preheating treatment, the mass of residual material in the loading device 2 is 490 kg. Five re-feeds are made to the loading device 2, each time with 100 kg of material. Before the first re-feed, the position of the loading device 2 is lowered by 100 mm using the displacement device 103. Before the second re-feed to the fifth re-feed, the position of the loading device 2 is lowered by 80 mm respectively. The interval between any two re-feeds is 40 minutes.

[0048] Example 2

[0049] A silicon crystal rod re-investment method comprises the following steps:

[0050] After the finishing of a silicon crystal rod is completed, the position of the loading device 2 is raised to 210mm relative to the standard zero position. The standard zero position means that the upper port of the loading device 2 and the upper port of the annular heating zone 102 inside the heating device 1 are located in the same plane. The position of the loading device 2 remains unchanged as a preheating crucible position. The lower end portion of the loading device 2 is accommodated in the interior of the heating device 1. The height of the loading device 2 is 700mm, and the height of the annular heating zone 102 is 260mm. The heating device 1 is used to preheat the loading device 2. The preheating time is 20min. The annular heating zone 102 is heated, and the heating power used by the heater is 80KW.

[0051] After preheating treatment, the mass of residual material in the loading device 2 is 480 kg. Five re-feeds are made to the loading device 2, each time with 100 kg of material. Before the first re-feed, the position of the loading device 2 is lowered by 100 mm using the displacement device 103. Before the second re-feed to the fifth re-feed, the position of the loading device 2 is lowered by 80 mm respectively. The interval between any two re-feeds is 45 minutes.

[0052] Example 3

[0053] A silicon crystal rod re-investment method comprises the following steps:

[0054] After the finishing of a silicon crystal rod is completed, the position of the loading device 2 is raised to 170mm relative to the standard zero position. The standard zero position means that the upper port of the loading device 2 and the upper port of the annular heating zone 102 inside the heating device 1 are located in the same plane. The position of the loading device 2 remains unchanged as a preheating crucible position. The lower end portion of the loading device 2 is accommodated in the interior of the heating device 1. The height of the loading device 2 is 700mm, and the height of the annular heating zone 102 is 240mm. The heating device 1 is used to preheat the loading device 2. The preheating time is 30min. The annular heating zone 102 is heated, and the heating power used by the heater is 80KW.

[0055] After preheating treatment, the mass of residual material in the loading device 2 is 500 kg. Five re-feeds are made to the loading device 2, each time with 100 kg of re-feed. Before the first re-feed, the position of the loading device 2 is lowered by 100 mm using the displacement device 103. From the second re-feed to the fifth re-feed, the position of the loading device 2 is lowered by 80 mm respectively. The interval between any two re-feeds is 50 minutes.

[0056] Example 4

[0057] A silicon crystal rod re-investment method comprises the following steps:

[0058] After the finishing of a silicon crystal rod is completed, the position of the loading device 2 is raised to 180mm relative to the standard zero position. The standard zero position means that the upper port of the loading device 2 and the upper port of the annular heating zone 102 inside the heating device 1 are located in the same plane. The position of the loading device 2 remains unchanged as a preheating crucible position. The lower end portion of the loading device 2 is accommodated in the interior of the heating device 1. The height of the loading device 2 is 700mm, and the height of the annular heating zone 102 is 260mm. The heating device 1 is used to preheat the loading device 2. The preheating time is 15min. The annular heating zone 102 is heated, and the heating power used by the heater is 85KW.

[0059] After preheating treatment, the mass of residual material in the loading device 2 is 500 kg. Five re-feeds are made to the loading device 2, each time with 100 kg of re-feed. Before the first re-feed, the displacement device 103 is used to lower the position of the loading device 2 by 100 mm. From the second re-feed to the fifth re-feed, the position of the loading device 2 is lowered by 80 mm respectively. The interval time between any two re-feeds is 55 minutes.

[0060] Example 5

[0061] A silicon crystal rod re-investment method comprises the following steps:

[0062] After the finishing of a silicon crystal rod is completed, the position of the loading device 2 is raised to 205mm relative to the standard zero position. The standard zero position means that the upper port of the loading device 2 and the upper port of the annular heating zone 102 inside the heating device 1 are located in the same plane, and the position of the loading device 2 remains unchanged as a preheating crucible position. The lower end portion of the loading device 2 is accommodated in the heating device 1. The height of the loading device 2 is 680mm, and the height of the annular heating zone 102 is 240mm. The heating device 1 is used to preheat the loading device 2. The preheating time is 15min. The annular heating zone 102 is heated, and the heating power used by the heater is 85KW.

[0063] After preheating treatment, the mass of residual material in the loading device 2 is 500kg. Five re-feeds are made to the loading device 2, each time with 100kg of re-feed. Before the first re-feed, the displacement device 103 is used to lower the position of the loading device 2 by 100mm, and before the second re-feed, the position of the loading device 2 is lowered by 95mm, and before the third re-feed, the position of the loading device 2 is lowered by 90mm, and before the fourth re-feed, the position of the loading device 2 is lowered by 85mm, and before the fifth re-feed, the position of the loading device 2 is lowered by 80mm. The interval time between any two re-feeds is 60min.

[0064] Example 6

[0065] A method for re-investing silicon crystal rods, which differs from embodiment 5 in that:

[0066] After preheating treatment, the mass of residual material in the loading device 2 is 500 kg. Five re-feeds are made to the loading device 2, each time with 80 kg of re-feed. Before the first re-feed, the displacement device 103 is used to lower the position of the loading device 2 by 100 mm. Before the second re-feed, the position of the loading device 2 is lowered by 90 mm. Before the third re-feed, the position of the loading device 2 is lowered by 80 mm. Before the fourth re-feed, the position of the loading device 2 is lowered by 70 mm. Before the fifth re-feed, the position of the loading device 2 is lowered by 60 mm. The interval time between any two re-feeds is 60 minutes.

[0067] Comparative Example 1

[0068] A silicon crystal rod re-investment method comprises the following steps:

[0069] After the finishing of a silicon crystal rod is completed, the position of the loading device 2 is at the standard zero position, which means that the upper port of the loading device 2 and the upper port of the annular heating zone 102 inside the heating device 1 are located in the same plane, and the position of the loading device 2 remains unchanged as a preheating crucible position, and the lower end portion of the loading device 2 is accommodated in the interior of the heating device 1. The height of the loading device 2 is 700 mm, and the height of the annular heating zone 102 is 260 mm. The heating device 1 is used to preheat the loading device 2, and the preheating time is 45 minutes. The annular heating zone 102 is heated, and the heating power used by the heater is 80KW.

[0070] After preheating, the mass of the remaining material in the loading device 2 is 480 kg. Five re-feeds are made to the loading device 2, each time with 100 kg of material. Before each re-feed, the displacement device 103 is used to lower the position of the loading device 2 by 30 mm. The interval between any two re-feeds is 60 minutes.

[0071] From the above, it can be seen that the silicon crystal rod re-feeding method of the present invention, through the coordination of the conditions of each step, can avoid the direct baking of the straight wall and the upper edge of the loading device by the heating device, can effectively reduce the bulging of the straight wall and the collapse of the upper edge of the loading device, can reduce the heating deviation of the solid material block in the loading device by the heating zone of the heating device to a certain extent, and can effectively improve the material efficiency.

[0072] In the re-feeding method of silicon crystal rods in Example 1, the material blocks inside the loading device are actually in the shape of a small hill, and there is no accumulation of material blocks in the upper area of ​​the straight wall of the loading device. This results in that even if solid silicon is added, the solid silicon does not share the baking heat of the heating zone on the straight wall of the loading device, the efficiency is low, and the total time of the re-feeding method is relatively long; in the actual process of adding materials, melting materials and pulling crystals, the baking time of the straight wall and the upper edge of the loading device by the heating device runs through the entire operation cycle of the single crystal furnace, which reduces the service life of the upper part of the straight wall of the loading device, and increases the collapse and softening abnormality rate of the loading device, and may even lead to premature shutdown of the furnace during the crystal pulling process, resulting in waste of production capacity.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for re-investing silicon crystal rods, characterized in that: The following steps are involved: After the preparation of a silicon crystal rod is completed, the position of the loading device is raised to 170-210 mm relative to the standard zero position, the lower end portion of the loading device is accommodated in the interior of the heating device, and the heating device is used to preheat the loading device; After the preheating treatment, the material loading device is repeatedly charged with materials, and before each repeated charging, the position of the material loading device is lowered by 60 to 100 mm.

2. The silicon ingot re-investment method according to claim 1, characterized in that: The standard zero position means that the upper port of the material loading device and the upper port of the annular heating area inside the heating device are located in the same plane.

3. The silicon ingot re-investment method according to claim 1, characterized in that: The time between any two consecutive re-dosing is 40 to 60 minutes.

4. The method for re-investing silicon crystal rods according to claim 1, characterized in that: The mass of the re-feeding each time is 15% to 25% of the mass of the remaining material in the loading device after the preheating treatment.

5. The silicon crystal rod re-investment method according to claim 1 or 4, characterized in that: The mass of the remaining material in the loading device after the preheating treatment is 480-500 kg.

6. The silicon ingot re-investment method according to claim 1, characterized in that: The number of times of re-feeding is 4 to 7 times.

7. The silicon ingot re-investment method according to claim 1, characterized in that: The height of the loading device is 650-750 mm.

8. The silicon ingot re-investment method according to claim 1, characterized in that: The heating device comprises a heat-insulating shell, a heater and a displacement device, wherein the heater forms an annular heating zone inside the heat-insulating shell; The displacement device is used to adjust the position of the loading device.

9. The method for re-investing silicon crystal rods according to claim 8, characterized in that: The height of the annular heating zone is 230-270 mm.

10. The silicon ingot re-investment method according to claim 8, characterized in that: The preheating time is 10 to 30 minutes.

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