A first crucible for growing silicon single crystals by continuous feeding using a Czochralski method and its melt and crystal pulling device

Abstract

The present invention discloses a first crucible for continuously feeding and growing silicon single crystals by a Czochralski method, as well as its melt and crystal pulling device. The main body of the first crucible is annular in the x-y plane, and is provided with one or more z-direction openings and a material trough that is annular or annular in cross section in the horizontal plane. A plurality of downward drainage channels are provided below the material trough, and a filter plate is provided near the junction of the drainage channel and the material trough. This design has many advantages: the system has high thermal efficiency, the melt crucible and the crystal pulling crucible are close to each other, eliminating the thermal resistance of the inner quartz partition and reducing energy consumption; the molten silicon has a low oxygen content, and oxygen volatilization is promoted by optimizing the crucible temperature field, controlling melt convection, and expanding the free liquid surface, and precise control is achieved by combining with segmented heating; the process parameters are independently adjustable, and the layered design of the two crucibles minimizes mutual interference; the crystal pulling stability is high, the large molten silicon liquid surface promotes the volatilization of impurity particles, the drainage channel extends the migration path, and the blocking effect of the filter plate effectively suppresses crystal transformation defects.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon single crystal preparation, in particular to a first crucible for continuously feeding and growing silicon single crystals using granular silicon as raw material by a Czochralski method, and its melt and crystal pulling device. Background Art

[0002] The double-layer crucible of the present invention is close to the existing Czochralski method for continuously feeding and growing silicon single crystals using granular silicon as raw material. The outer layer of the crucible continuously melts the granular silicon material, and the molten silicon is transported to the inner layer of the crucible through the through holes or gaps in the bottom layer, thereby realizing continuous crystal pulling in the inner layer of the crucible.

[0003] The existing technology has the following deficiencies, which affect the quality and production cost of silicon single crystals:

[0004] a) Low thermal efficiency. Due to the low thermal conductivity of quartz, the inner quartz wall blocks the effective heat convection of the molten silicon, making the outer layer of the crucible form a heat shield for the inner layer of the crucible, resulting in a large temperature difference between the inner and outer layers of molten silicon. In order to maintain the appropriate temperature of the inner layer of molten silicon, the output power of the heater must be increased, resulting in low thermal efficiency, high power consumption, and increased product costs. The existing technology with an independent molten silicon system also has the disadvantage of low heating and heat preservation efficiency. It is well known that energy consumption is an important component of the cost of silicon single crystals;

[0005] b) The oxygen content of molten silicon is high and difficult to control. Since the outer layer of the crucible forms a heat shield for the inner layer of the crucible, the temperature of the outer molten silicon is high and the convection is strong, resulting in a large amount of oxygen in the quartz crucible being dissolved into the molten silicon. At the same time, the surface area of ​​the inner crucible molten silicon is reduced, which hinders the oxygen in the molten silicon from passing through the SiO X volatilizes in the form of oxygen, which eventually leads to an increase in the oxygen content of the silicon single crystal;

[0006] c) It is easy to produce crystal transformation. In the process of pulling silicon single crystals, tiny silicon oxide particles will fall off from the quartz crucible from time to time. Under normal circumstances, these particles will float to the interface of silicon single crystals as gas SiO X This is one of the reasons why the crucible diameter in the crystal pulling process must be 2.5 to 3 times the diameter of the crystal. Due to the smaller diameter of the crucible's inner layer, these silicon oxide particles are more likely to float to the crystal plane of the silicon single crystal, which can easily cause crystal deformation, terminate the crystal pulling process, reduce production efficiency, and increase manufacturing costs.

[0007] d) Silicon dust is prone to falling during feeding. The feeding end of the existing double-layer crucible is designed to be open. When dust is present in the crushed silicon, it easily falls onto the molten silicon in the quartz crucible and the surface of the crystal. The silicon dust that has not yet melted can easily cause crystal pulling failure.

[0008] e) The system has a single function, limited to continuous feeding, and lacks other additional features. For example, the radial temperature distribution and longitudinal temperature gradient distribution in a silicon single crystal ingot cannot be adjusted independently; nor is there any further oxygen control or reduction function. Summary of the Invention

[0009] The object of the present invention is to provide a first crucible and its melt and crystal pulling device for continuously feeding and growing silicon single crystals by the Czochralski method using granular silicon as raw material, so as to at least improve one of the above-mentioned deficiencies.

[0010] In a first aspect, the present invention provides a first crucible for continuously feeding and growing silicon single crystals by a Czochralski method, characterized in that: the main body of the first crucible is annular in the xy plane cross section, and the annular shape includes a quasi-circular ring, a quasi-elliptical ring or a quasi-polygonal ring; the first crucible is provided with one or more z-direction openings, and a material trough that is annular or ring-slot-shaped in the horizontal cross section; at least one downward drainage channel is provided below the material trough, and a filter plate is provided near the junction of the drainage channel and the material trough.

[0011] In this application document, the so-called "ring-segment shape" refers to a portion of a quasi-circular ring, such as a sector ring and a quasi-sector ring.

[0012] Compared with the prior art, the beneficial effects of the embodiments of the present invention when applied to the melt and crystal pulling device for continuously feeding and growing silicon single crystals by the Czochralski method of this application document are:

[0013] a) The system has high thermal efficiency.

[0014] The first crucible of the molten material is located above and adjacent to the second crucible for crystal pulling, eliminating the barrier of the inner quartz partition wall to the heat convection and heat conduction of the molten silicon in the prior art. Therefore, the energy consumption of the silicon single crystal pulling process is low and the system thermal efficiency is high.

[0015] b) The oxygen content of molten silicon is low and easy to control.

[0016] Silicon melting and crystal pulling are carried out in the first crucible and the second crucible respectively. The heating power of the first crucible is large, and the surface temperature of the crucible and granular silicon is high. However, there is less molten silicon in the first crucible, the convection is weak, and the contact area between the molten silicon and the crucible is small, so less impurity oxygen enters the molten silicon;

[0017] The liquid level in the second crucible is low, and the temperature of the molten silicon near the second crucible is low, so the convection of the molten silicon is weak, and less impurity oxygen enters the molten silicon;

[0018] The free surface area of ​​the molten silicon in the second crucible is large, which is conducive to the volatilization of oxygen impurities.

[0019] Therefore, compared with the prior art of continuously feeding and pulling silicon single crystals with a double-layer crucible, the present invention is easier to control the oxygen content in the silicon single crystal and obtain silicon single crystals with lower oxygen content.

[0020] c) Silicon melting and crystal pulling are regulated separately.

[0021] Silicon melting and crystal pulling are carried out in the first crucible and the second crucible respectively. The two crucibles are located at different heights of the heater. The heater is designed in sections, or the first crucible is provided with a separate first heater. The heating and insulation power can be adjusted separately. The two are less involved with each other, the process conditions are easy to adjust, and the impurity content is easy to control.

[0022] d) The crystal pulling process is stable and crystal transformation is not likely to occur.

[0023] Since the free liquid surface area of ​​the molten silicon is large, in the process of pulling the silicon single crystal, the tiny silicon oxide particles falling off the quartz crucible have a high probability of volatilizing in the form of gas before reaching the crystallization interface of the silicon single crystal after floating for a distance, and will not affect the normal growth of the silicon single crystal; the probability of the fine particles of silicon material leaking from the filter plate is small, the drainage channel path is long, and the fine silicon particles are easy to melt during the migration process, thereby preventing the normal growth of the silicon single crystal from being affected.

[0024] Furthermore, the outer wall of the inner ring edge of the material trough described in the present invention is designed to be an airflow guide surface with an oblique line or an arc on the xoz section. The inclination angle α of the oblique line or the arc is 20°~85°. On the one hand, it is conducive to the streamlined design of the process gas argon, so that the working conditions are stable and the turbulence is small; on the other hand, it provides stable heat reflection and thermal insulation near the crystal crystallization interface, reduces the radial temperature gradient near the crystallization interface, and makes the crystallization interface smooth, the stress is small, and the impurity distribution is uniform.

[0025] Furthermore, the outer edge of the first crucible is provided with at least one of a lug, a flange or a boss, which facilitates the first crucible to be fixed above the second crucible in various ways to achieve the function of melting material and transporting molten silicon to the second crucible.

[0026] Preferably, when the first crucible is fixed to a structural member in the furnace chamber, one or more trough cover plates distributed in an annular manner are provided at the trough opening of the first crucible.

[0027] Preferably, the trough cover is a porous filter made of ceramic or quartz. The beneficial effect of the trough cover is that it disperses and balances the air pressure inside and outside the trough during feeding, preventing silicon dust from drifting with the airflow and causing crystal pulling failure due to premature melting.

[0028] Furthermore, the total arc length of all the drainage channels where their outer diameters block the surface of the molten silicon in the second crucible is less than 1 / 2 of the inner circumference of the second crucible at that position, so as to reduce the area occupied by the molten silicon surface of the second crucible, thereby facilitating further control of the increase in oxygen content.

[0029] Preferably, the drainage channel is spirally descending in the circumferential direction of the second crucible, with a descending angle of γ, where 5°<γ<75°.

[0030] In this application document, the descent angle γ is defined as the ratio of the distance a point on the drainage channel descends along the rotating cylindrical surface of the crucible inner wall to the distance it moves on the cylindrical surface, which is the sine of the descent angle γ.

[0031] The spiral descending drainage channel lengthens the path of molten silicon flowing from the first crucible to the second crucible, giving the unmelted silicon particles sufficient time to melt;

[0032] Furthermore, when the drainage channel leads to below the liquid level of the molten silicon in the second crucible and the first crucible is fixed on a structural part in the furnace chamber, the spiral descending setting of the drainage channel, in conjunction with the rotation of the crucible in the crystal pulling process, produces a downward pressing effect on the molten silicon at the edge of the second crucible, which can suppress the upward thermal convection intensity of the molten silicon from the edge of the second crucible and reduce the oxygen impurities entering the molten silicon; further, the drainage channel, in conjunction with the rotation of the crucible in the crystal pulling process, also has a stirring effect on the molten silicon, so that the impurities are evenly distributed.

[0033] Multiple diversion channels are inserted into the molten silicon liquid surface to add and supplement molten silicon, which can realize large-scale continuous feeding. At the same time, they are inserted into the molten silicon liquid surface, which is beneficial to increasing the uniform mixing of the newly added molten silicon and the silicon melt, promoting the formation of a symmetrical flow field, and reducing the flow rate of the newly added molten silicon, which is beneficial to the stability of the crystal pulling environment.

[0034] Preferably, the first crucible is made of silicon nitride (Si3N4) or silicon oxynitride (Si2N2O), with the nitrogen content ranging from 4% to 40% by weight. Compared to quartz, silicon nitride (Si3N4) or silicon oxynitride (Si2N2O) has higher strength and softening points, making them more adaptable to the higher temperatures encountered during silicon melting. They are also more durable, enabling long-term use and reducing costs.

[0035] In the second aspect, the present invention provides a melt and crystal pulling device for continuously feeding and growing silicon single crystals by the Czochralski method, comprising: a feeding pipe, a second crucible, a carbon crucible side, a carbon crucible bottom, a second heater and a flow guide and temperature control screen. The aforementioned first crucible is arranged above the second crucible, and the first crucible and the second crucible are arranged coaxially. The vertical distance between the outer bottom of the material trough of the first crucible and the upper edge of the second crucible is less than 150 mm, and the distance includes a negative value, that is, the outer bottom of the material trough of the first crucible can be lower than the upper edge of the second crucible.

[0036] Combined with the design of the first crucible, the aforementioned beneficial effects are achieved.

[0037] The flow-guiding temperature control screen in this application document is used to assist in adjusting the heat dissipation rate of the silicon single crystal at a given location, and can be designed for either heat preservation or forced heat dissipation.

[0038] Furthermore, the drainage channel below the trough leads to below the molten silicon liquid level of the second crucible. Its beneficial effects are:

[0039] a) Some unmelted tiny silicon particles that can pass through the filter plate provided in the first crucible trough will temporarily float on the surface of the molten silicon in the diversion channel and further melt, thus avoiding directly entering the second crucible and interfering with normal crystal growth;

[0040] b) a drainage channel extending into the second crucible below the surface of the molten silicon liquid, which, in conjunction with the rotation of the second crucible, can stir the molten silicon, thereby making the temperature field and the impurities in the molten silicon uniform;

[0041] c) The molten silicon flowing into the second crucible enters below the molten silicon liquid level, which has little interference with the molten silicon liquid level, making the crystal pulling process stable.

[0042] Preferably, the lug, flange or boss of the first crucible is connected to the melt and the crystal pulling device in at least one of the following ways:

[0043] a) the first crucible is connected to the second crucible via the lug, flange or boss, and the first crucible and the second crucible rotate synchronously and in the same direction during the growth of the silicon single crystal to ensure uniform feeding and heating around the circumference;

[0044] b) the first crucible is connected to the carbon crucible side via the lug, flange, or boss, and during the growth of the silicon single crystal, the first crucible and the second crucible rotate synchronously and in the same direction, so that circumferential feeding and heating are uniform and the first crucible is securely positioned;

[0045] c) The first crucible is connected to the fixed structure in the furnace body through the lug, flange or boss. During the growth of the silicon single crystal, the first crucible is fixed in position and does not rotate. In conjunction with the rotation of the second crucible in the crystal pulling process, a stirring effect can be formed on the molten silicon, so that the temperature field and the impurities in the molten silicon are evenly distributed.

[0046] Preferably, there is no intermediate partition between the trough section of the first crucible and the second heater or the first heater, and the first crucible directly receives heat radiation from the second heater or the first heater, which can achieve higher thermal efficiency and lower impurity carbon pollution.

[0047] Preferably, the projection vector of the downward extension direction of the drainage channel from the trough on the xy plane is aligned with the rotation direction of the second crucible. This advantageously provides the drainage channel with a downward pressure on the molten silicon at the edge of the second crucible, thereby suppressing the intensity of upward thermal convection of the molten silicon from the edge of the second crucible and reducing the amount of oxygen impurities entering the molten silicon.

[0048] Furthermore, the melt and crystal pulling device have at least one of the following features:

[0049] a) The second crucible and the first crucible are both heated by a second heater, and the heating power of the second heater is designed in sections along the z-direction to provide appropriate power distribution to the first crucible and the second crucible;

[0050] b) the first crucible is heated by a separate first heater, and the first heater and the second heater cooperate to provide the first crucible and the second crucible with appropriate heating power;

[0051] c) the relative position of the second crucible and the first crucible, and the relative position of the airflow guide surface of the first crucible and the silicon single crystal growth interface are fixed, and the heat transfer working conditions are stable;

[0052] d) The relative positions of the flow-guiding temperature-control screen and the silicon single crystal growth interface are fixed, and the heat transfer working conditions are stable.

[0053] A reasonable temperature gradient near the crystallization plane of a silicon single crystal ingot requires the lowest possible radial temperature difference and the highest possible axial temperature gradient. The former is to obtain a flat crystallization plane, reduce the stress of the silicon single crystal ingot and the uneven distribution of impurities in the cross section, and obtain a silicon single crystal ingot with a larger diameter; the latter is to obtain a higher single crystal growth rate.

[0054] To achieve this goal, the present invention employs a first crucible positioned immediately above a second crucible. By adjusting the height, width, and shape of the first crucible, the reflection of molten silicon heat radiation and the insulation length, location, and intensity near the silicon single crystal growth interface are controlled. Furthermore, the position of a flow-guiding temperature control screen positioned above the first crucible independently adjusts the forced cooling effect distal to the crystallization interface. These two independent controls achieve both a reduced radial temperature difference in the silicon single crystal and a high axial temperature gradient. This results in a smooth crystallization interface, reduced stress, the ability to pull silicon single crystals with larger cross-sectional areas, high pulling speeds, and reduced energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0056] Figure 1 Schematic diagram of a first crucible, melt, and crystal pulling device for continuously feeding and growing a silicon single crystal using the Czochralski method provided in Example 1 of the present application;

[0057] Figure 2 A schematic diagram of the first crucible provided in Example 1;

[0058] Figure 3 Schematic diagram of a first crucible, melt, and crystal pulling device for growing a silicon single crystal by continuous feeding using a Czochralski method according to Example 2 of the present application;

[0059] Figure 4 A schematic diagram of a first crucible provided in Example 2;

[0060] Figure 5 Schematic diagram of a first crucible, melt, and crystal pulling device for continuously feeding and growing a silicon single crystal using a Czochralski method, provided in Example 3 of the present application;

[0061] Figure 6 A schematic diagram of a first crucible provided in Example 3;

[0062] Figure 7 Schematic diagram of a first crucible, melt, and crystal pulling device for continuously feeding and growing a silicon single crystal using a Czochralski method, as provided in Example 4 of the present application;

[0063] Figure 8 A schematic diagram of a first crucible provided in Example 4;

[0064] Icons: 100-device; 108-first crucible; 1-carbon crucible bottom; 2-carbon crucible side; 3-second crucible; 4-flow guide temperature control screen; 51-first heater; 52-second heater; 6-feeding pipe; 71-granular silicon; 72-molten silicon; 721-free liquid surface of molten silicon; 73-silicon single crystal ingot; 74-crystalline silicon particles; 81-feed trough; 83-filter hole plate; 84-diversion channel; 841-outer inclined wall of diversion channel; 85-airflow guide surface; 86-feed trough cover; 87-lug; 88-flange; 89-boss. DETAILED DESCRIPTION

[0065] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0066] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0067] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0068] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0069] In addition, the terms "first", "second", etc., if used, are merely used to distinguish and describe, and should not be understood as indicating or implying relative importance.

[0070] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0071] Example 1

[0072] like Figure 1 、 Figure 2 As shown, this embodiment provides a first crucible 108 for continuously feeding and growing silicon single crystals by the Czochralski method. The main body of the first crucible 108 is in the shape of a circular ring in the xy plane cross section, and the main body is provided with a material trough 81 with a z-direction opening. The material trough 81 is in the shape of a ring, and four downward drainage channels 84 are provided below the material trough 81. A filter plate 83 is provided at the junction of the drainage channel 84 and the material trough 81.

[0073] The outer wall section of the inner ring edge of the material trough 81 of the first crucible 108 is an arc-shaped airflow guide surface 85 , and the airflow guide surface 85 includes a section with an inclination angle α of 20° to 85° from bottom to top.

[0074] A boss 89 is provided at the bottom of the outer edge of the first crucible 108 for connecting with the second crucible 3 .

[0075] The four downward drainage channels 84 of the material trough 81 have an outer diameter of 40 mm, and the total arc length of the molten silicon surface in the second crucible 3 blocked by them is much smaller than 1 / 2 of the inner circumference of the second crucible 3 at that position.

[0076] The first crucible 108 is made of Si 3 N 4 or Si 2 N 2 O, wherein the nitrogen content is 10% by weight.

[0077] This embodiment also provides a melt and crystal pulling apparatus 100 for continuously feeding and growing a silicon single crystal using the Czochralski method, comprising: a feed pipe 6, a second crucible 3, a carbon crucible rib 2, a carbon crucible bottom 1, a second heater 52, a first crucible 108, and a flow-guiding and temperature-controlling screen 4. The first crucible 108 is coaxially arranged with the second crucible 3 and shares the second heater 52. The boss 89 of the first crucible 108 is positioned on the upper edge of the second crucible 3. During the silicon single crystal growth process, the first crucible 108 and the second crucible 3 rotate synchronously and in the same direction. During the crystal pulling process, as the first crucible 108 rotates, additional granular silicon 71 is continuously added to the trough 81 of the first crucible 108. After melting, the granular silicon 71 is transported through the drainage channel 84 to below the free liquid surface 721 of the molten silicon in the second crucible 3.

[0078] Compared with the prior art, this embodiment has the following beneficial effects:

[0079] a) High system thermal efficiency. The first crucible 108 for the melt is placed above the second crucible 3 for crystal pulling, sharing the second heater 52. This eliminates the inner quartz wall's barrier to heat convection and conduction in the molten silicon, resulting in high thermal efficiency.

[0080] b) Silicon single crystals have low oxygen content and are easy to control.

[0081] Silicon melting and crystal pulling are performed in the first crucible 108 and the second crucible 3, respectively. The heating power density of the first crucible 108 is large, and the surface temperatures of the first crucible 108 and the granular silicon 71 are high. However, there is little molten silicon 72 in the first crucible 108, the convection is weak, and the contact area between the molten silicon and the crucible is small, so less impurity oxygen enters the molten silicon 72.

[0082] The first crucible 108 contains Si3N4 or Si2N2O with a weight ratio of 10% N element. A higher proportion of Si3N4 or Si2N2O is beneficial to further reduce the oxygen element entering the molten silicon.

[0083] The liquid level in the second crucible 3 is low, the temperature of the molten silicon 72 near the second crucible 3 is low, and the convection of the molten silicon 72 is weak. Therefore, less impurity oxygen enters the molten silicon 72.

[0084] The surface area of ​​the free liquid surface 721 of the molten silicon in the second crucible 3 is large, which is conducive to the volatilization of oxygen impurities.

[0085] Therefore, compared with the prior art double-layer crucible continuous feeding and pulling of silicon single crystals, this embodiment is more likely to control the oxygen content in the silicon single crystals and obtain silicon single crystals with lower oxygen content.

[0086] c) Silicon melting and crystal pulling are performed in the first crucible 108 and the second crucible 3 respectively, and their process environments can be adjusted separately. Crystal pulling and melt are less involved with each other, and the process is stable.

[0087] d) The crystal pulling process is stable and crystal transformation is not likely to occur. In this embodiment, due to the large area of ​​the molten silicon free surface 721, during the process of pulling the silicon single crystal ingot 73, tiny silicon oxide particles that fall off the first crucible 108 and the second crucible 3 will evaporate as gas before floating a long distance and reaching the silicon single crystal crystallization interface, thus not affecting the normal growth of the silicon single crystal.

[0088] e) The first crucible 108 is made of a compound of Si3N4 or Si2N2O containing 10% by weight of nitrogen. Compared to quartz, the first crucible 108 has higher strength and stability in a high-temperature environment of an inert gas, is more adaptable to the process conditions of silicon melting, is more durable, and is conducive to long-term use, thereby reducing costs.

[0089] f) First crucible 108 maintains heat near the crystallization interface. Its airflow guide surface 85 reflects radiation onto the underlying silicon surface, increasing the edge temperature of the crystallization interface and reducing the radial temperature gradient near the interface. This, combined with the cooling effect of the guide temperature control shield 4 on the upper portion of the silicon single crystal ingot 73, achieves the goal of controlling both the radial temperature gradient near the crystallization interface and the longitudinal temperature gradient of the silicon crystal.

[0090] Example 2

[0091] This embodiment provides a first crucible 108 for growing silicon single crystals by continuous feeding using the Czochralski method. Similarities with Example 1 are not repeated here. Differences from Example 1 include a lug 87 formed on the outer top edge of the first crucible 108, which overlaps the carbon crucible side 2 and forms a coaxial arrangement with the second crucible 3. The first crucible 108 and the second crucible 3 share a second heater 52. The material trough 81 has three z-direction drainage channels 84.

[0092] In addition to the beneficial effects of Example 1, this embodiment has the beneficial effects of being more stable and not affected by possible deformation of the second crucible 3 because the first crucible 108 is overlapped on the carbon crucible side 2 .

[0093] Example 3

[0094] like Figure 5 、 Figure 6 As shown, this embodiment differs from embodiment 1 in that:

[0095] a) In this embodiment, the first crucible 108 is provided with a flange 88, which replaces the lug 87 in Example 2. The flange 88 is connected to a fixed structure in the furnace body. During the growth of the silicon single crystal, the first crucible 108 is fixed in position and does not rotate:

[0096] b) In this embodiment, the first crucible 108 is provided with two fan-shaped troughs 81 opening in the z direction, two feed pipes 6 , and a filter plate 83 vertically disposed at the ends of the fan-shaped troughs 81 ;

[0097] c) In this embodiment, the first crucible 108 is provided with two drainage channels 84. The two drainage channels 84 are spirally descending in the circumferential direction near the inner wall of the first crucible 108. The descending angle γ is 10°. The inner diameter of the second crucible 3 is 800 mm.

[0098] d) In this embodiment, the flange 88 of the first crucible 108 is connected to a fixed structure within the furnace body. During the growth of the silicon single crystal, the first crucible is fixed in position and does not rotate. There is no intermediate barrier between the trough 81 section of the first crucible 108 and the first heater 51. The first crucible 108 is directly exposed to heat radiation from the first heater 51.

[0099] e) In this embodiment, a ring-shaped trough cover 86 is provided at the opening of the trough 81 of the first crucible 108. The trough cover 86 is a porous filter made of quartz ceramic material.

[0100] In addition to the beneficial effects of Example 1, this embodiment also has the following beneficial effects:

[0101] a) The first crucible 108 is more stably and reliably placed;

[0102] b) The first crucible 108 does not rotate, and a trough cover 86 with a filter structure is placed on it. This provides a more reliable seal between the feed pipe 6 and the trough cover 86, preventing silicon powder in the granular silicon 71 from drifting to the vicinity of the crystallization interface and interfering with the growth of the silicon single crystal ingot 73;

[0103] c) The first crucible 108 does not rotate, and the outer inclined wall 841 of the drainage channel cooperates with the rotation of the second crucible 3 during the crystal pulling process to exert a downward pressure on the molten silicon 72 at the edge of the second crucible 3, thereby suppressing the intensity of the thermal convection of the molten silicon 72 upward from the edge of the second crucible 3 and reducing the oxygen impurities entering the molten silicon 72;

[0104] The spirally descending drainage channel 84 not only suppresses the thermal convection movement of the molten silicon 72 upward from the edge of the second crucible 3, but also lengthens the path of the molten silicon 72 flowing from the first crucible 108 to the second crucible 3, allowing sufficient time for the unmelted silicon particles to melt.

[0105] The diversion channel 84 cooperates with the rotation of the second crucible 3 in the crystal pulling process and stirs the molten silicon 72 to ensure uniform distribution of impurities.

[0106] d) There is no intermediate barrier between the trough 81 section of the first crucible 108 and the first heater 51 , so the first crucible 108 directly receives heat radiation from the first heater 51 , effectively improving heating efficiency and facilitating independent control of heating power;

[0107] e) The filter plate 83 vertically arranged at the end of the fan-shaped material trough 81 increases the buffer distance and buffer time of the molten silicon flow, which is conducive to the complete melting of the incompletely melted crystalline silicon particles 74 and prevents them from interfering with the normal growth of crystalline silicon.

[0108] Example 4

[0109] like Figure 7 、 Figure 8 As shown, the difference between this embodiment and embodiment 2 is that:

[0110] a) In this embodiment, the boss 89 at the bottom of the trough 81 of the first crucible 108 replaces the lug 87 in Example 2. The boss 89 is positioned on the carbon crucible side 2, providing greater stability. There is no barrier between the annular trough 81 and the first heater 51, allowing the first crucible 108 to directly receive heat radiation from the first heater 51, effectively improving heating efficiency and facilitating independent control of heating power.

[0111] b) In this embodiment, the drainage channel 84 below the free surface 721 of the molten silicon is widened in the circumferential direction of the second crucible 3. This has the beneficial effect of providing a buffer zone for the incompletely melted crystalline silicon particles 74, allowing them to fully melt and prevent them from interfering with the normal growth of crystalline silicon.

[0112] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A melt and crystal pulling device for continuously feeding and growing silicon single crystals by the Czochralski method, characterized in that: It includes a first crucible, a second crucible, a feeding pipe, a carbon crucible side, a carbon crucible bottom, a second heater and a flow guide temperature control screen; wherein the first crucible of the molten material is located above the second crucible for crystal pulling, the first crucible and the second crucible are coaxially arranged, the main body of the first crucible is annular in the xy plane section, the annular shape includes a quasi-circular ring, a quasi-elliptical ring or a quasi-polygonal ring, the first crucible is provided with one or more z-direction openings, a material trough which is annular or ring-slot shaped in the horizontal plane section, the material trough is above the free liquid surface of the molten silicon, and at least one downward drainage channel is provided below the material trough, and a filter plate is provided near the junction of the drainage channel and the material trough; the distance between the outer bottom of the material trough and the upper edge of the second crucible in the z direction is less than 150 mm; the outer wall of the inner ring edge of the material trough is an airflow guide surface which is an oblique line or arc in the xoz section, and the inclination angle α of the oblique line or arc from bottom to top is 20°~85°.

2. The melt and crystal pulling device according to claim 1, characterized in that: The outer edge of the first crucible is provided with at least one structure selected from the group consisting of a lug, a flange, and a boss.

3. The melt and crystal pulling device according to claim 1, characterized in that: One or more trough cover plates are arranged in an annular arrangement at the opening of the trough.

4. The melt and crystal pulling device according to claim 3, characterized in that: The trough cover is a filter screen with a porous structure made of ceramic or quartz material.

5. The melt and crystal pulling device according to claim 1, characterized in that: The total arc length of the location where the outer diameter of the drainage channel blocks the surface of the molten silicon in the second crucible is less than 1 / 2 of the inner circumference of the second crucible at that location.

6. The melt and crystal pulling device according to claim 1, characterized in that: The drainage channel is in a spiral descending shape in the circumferential direction of the second crucible, with a descending angle of γ, 5°<γ<75°.

7. The melt and crystal pulling device according to claim 1, characterized in that: The material of the first crucible contains silicon nitride (Si3N4) or silicon nitride oxide (Si2N2O), and the proportion of nitrogen in the material of the first crucible is 4% to 40% by weight.

8. The melt and crystal pulling device according to claim 1, characterized in that: The drainage channel below the material trough leads to below the free liquid surface of the molten silicon in the second crucible.

9. The melt and crystal pulling device according to claim 2, characterized in that: The lug, flange or boss of the first crucible is connected to the melt and the crystal pulling device in at least one of the following ways: a) the first crucible is connected to the second crucible via the lug, flange or boss, and the first crucible and the second crucible rotate synchronously and in the same direction during the growth of the silicon single crystal; b) the first crucible is connected to the carbon crucible side via the lug, flange or boss, and the first crucible and the second crucible rotate synchronously and in the same direction during the growth of the silicon single crystal; c) The first crucible is connected to a fixed structure in the furnace body through the lug, flange or boss. During the growth of the silicon single crystal, the first crucible is fixed in position and does not rotate.

10. The melt and crystal pulling device according to claim 1, wherein: There is no intermediate barrier between the trough section of the first crucible and the second heater, and the first crucible is directly subjected to heat radiation from the second heater; or The first crucible is heated by a separate first heater, and the second crucible is heated by a second heater. There is no intermediate barrier between the trough section of the first crucible and the first heater, and the first crucible is directly subjected to heat radiation from the first heater.

11. The melt and crystal pulling device according to claim 8, characterized in that: The projection vector direction of the downward extension direction vector of the drainage channel from the material trough on the xy plane is the same as the rotation direction of the second crucible.

12. The melt and crystal pulling device according to claim 1, wherein: At least one of the following characteristics: a) the second crucible and the first crucible are heated by the same set of heaters, the heating power of the heaters being designed in sections along the z-direction; wherein the same set of heaters is the second heater; b) the first crucible is heated by a separately provided first heater; the second crucible is heated by the second heater; c) during the crystal pulling process, the relative positions of the second crucible and the first crucible are fixed, and the relative positions of the airflow guide surface of the first crucible and the silicon single crystal growth interface are fixed; d) During the crystal pulling process, the relative positions of the flow guide temperature control screen and the silicon single crystal growth interface are fixed.

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