Single crystal furnace heating structure and single crystal furnace

Abstract

The present application relates to a single crystal furnace heating structure and a single crystal furnace. The single crystal furnace heating structure comprises: an insulating base plate; a plurality of heating units, which are arranged around the edge of the insulating base plate; a power supply unit, which is configured to apply an electric signal to the heating units; conductive blocks, which are movably connected between adjacent heating units, such that the plurality of heating units are connected in series and match the power supply unit to form a loop; and an insulating connection assembly, wherein one end of the insulating connection assembly is connected to the conductive blocks, the other end of the insulating connection assembly is configured to be connected to a crucible support shaft, and the insulating connection assembly drives the conductive blocks to ascend and descend along with the lifting of the crucible shaft so as to change the length of heating areas of the heating units in a first direction which is an axial direction of the crucible support shaft.

Description

Single crystal furnace heating structure and single crystal furnace

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202310952401.6 filed in China on July 31, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of single crystal furnaces, and in particular to a single crystal furnace heating structure and a single crystal furnace. Background Art

[0004] Currently, in the production of single crystal silicon, both the melting of polycrystalline silicon and the normal growth of single crystal silicon are inseparable from the heating device. The heating device is the most important core component of the thermal field structure of the Czochralski single crystal furnace. As the diameter of the crystal ingot continues to increase, the size standard of the equipment used to grow the crystal ingot has also become larger. As the size of the Czochralski single crystal furnace thermal field increases, the size of the heating device used in the furnace has also increased. The main function of the heating device is to provide heat to the polycrystalline silicon material in the quartz crucible, melting the initial solid raw material into a liquid state and ensuring the temperature gradient required for single crystal silicon growth, maintaining the normal growth of the single crystal silicon and guaranteeing the single crystal silicon crystallization rate.

[0005] Currently, during the pulling process, the crystal ingot continues to rise, but the position and area of ​​the heating zone of the heating device cannot be adjusted, which is not conducive to the uniformity of the axial temperature gradient of the crystal ingot.

[0006] Summary of the Invention

[0007] The present application provides a single crystal furnace heating structure and a single crystal furnace, which solve the problem that the heating zone of the heating device remains unchanged and affects the uniformity of the axial temperature gradient of the crystal rod.

[0008] The technical solution adopted in the embodiment of the present application is: a single crystal furnace heating structure, comprising:

[0009] A plurality of heating units, wherein the plurality of heating units are disposed around the edge of the insulating chassis;

[0010] a power supply unit, configured to apply an electrical signal to the heating unit;

[0011] A conductive block is movably connected between adjacent heating units so that the plurality of heating units are connected in series and cooperates with the power supply unit to form a loop;

[0012] An insulating connection component, one end of which is connected to the conductive block, and the other end of which is used to connect to the crucible support shaft. The insulating connection component moves up and down as the crucible support shaft rises and falls, thereby driving the conductive block to move up and down to change the length of the heating zone of the heating unit in a first direction, where the first direction is the axial direction of the crucible support shaft.

[0013] Optionally, each of the heating units includes a heating plate.

[0014] Optionally, each of the heating units includes at least two heating plates disposed at intervals, and at least two of the heating plates in the same heating unit are connected in series.

[0015] Optionally, each of the heating units includes a conductive connector disposed at an end away from the insulating chassis, and the conductive connector is connected between two adjacent heating plates.

[0016] Optionally, the conductive connector is a graphite clip.

[0017] Optionally, in the first direction, the thickness of the heating plate gradually decreases along a direction away from the insulating chassis.

[0018] Optionally, the insulating connection assembly includes an insulating bearing sleeve and a connecting component connected between the conductive block and the insulating bearing sleeve, and the insulating bearing sleeve is transmission-connected to the crucible support shaft, so that the insulating connection assembly rises and falls synchronously with the crucible transmission shaft, and does not rotate with the crucible support shaft when the crucible support shaft rotates.

[0019] Optionally, the connecting component includes:

[0020] a first insulating ring, the conductive block being connected to an outer circumferential surface of the first insulating ring;

[0021] a second insulating ring, sleeved inside the first insulating ring, and fixedly connected to the outside of the insulating bearing sleeve;

[0022] A plurality of connecting rods are connected between the first insulating ring and the second insulating ring.

[0023] Optionally, the power supply unit includes a positive electrode pin and a negative electrode pin, and the positive electrode pin and the negative electrode pin are respectively connected to different heating units.

[0024] An embodiment of the present application also provides a single crystal furnace, comprising the above-mentioned single crystal furnace heating structure, and also comprising a crucible and a crucible support shaft supporting the crucible, wherein the insulating connection assembly of the single crystal furnace heating device is connected to the crucible support shaft.

[0025] The present application has the beneficial effects of: the single crystal furnace heating structure disclosed herein includes multiple heating units, which are arranged around the edge of an insulating chassis. Adjacent heating units are connected in series via conductive blocks. The conductive blocks are connected to the crucible support shaft via an insulating connection assembly. The insulating connection assembly can move up and down with the crucible support shaft, thereby driving the conductive blocks to move up and down. This changes the connection position between the conductive blocks and the corresponding heating units, thereby changing the length of the heating zone of the heating unit in the axial direction of the crucible support shaft. This can improve the uniformity of the axial temperature gradient of the crystal ingot, thereby adjusting the oxygen content of crystal ingots of different lengths during the crystal pulling stage, achieving precise control of the oxygen content. At the same time, during the crystal ingot growth process, the length of the heating zone is adjusted as the crystal ingot length increases, reducing the change in the relative position between the heating zone and the crystal ingot in the axial direction of the crystal ingot, ensuring that the growth environment at the solid-liquid-gas triple point during crystal growth is always optimal, thereby achieving controllable crystal defects within the crystal ingot and growing a defect-free crystal ingot free of micro-defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a schematic diagram showing a single crystal furnace heating structure in an embodiment of the present application;

[0027] FIG2 is a schematic diagram of a single crystal furnace in an embodiment of the present application;

[0028] FIG3 is a schematic diagram of a bearing sleeve in an embodiment of the present application;

[0029] FIG4 is a schematic diagram showing a comparison of oxygen content during the growth of a crystal rod. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0031] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by people with ordinary skills in the field to which this disclosure belongs. The words "first", "second" and similar words used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "an" or "the" do not indicate a quantity limitation, but rather indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0032] 1 and 2 , this embodiment provides a single crystal furnace heating structure, including:

[0033] Insulation chassis 2,;

[0034] A plurality of heating units 1, wherein the plurality of heating units 1 are disposed around the edge of the insulating chassis 2;

[0035] a power supply unit, configured to apply an electrical signal to the heating unit;

[0036] The conductive block 4 is movably connected between adjacent heating units 1 so that the plurality of heating units 1 are connected in series and cooperates with the power supply unit to form a loop;

[0037] An insulating connection component, one end of which is connected to the conductive block 4, and the other end of which is used to connect to the crucible support shaft 30. The insulating connection component moves up and down as the crucible support shaft rises and falls, driving the conductive block 4 to move up and down to change the length of the heating zone of the heating unit 1 in a first direction, where the first direction is the axial direction of the crucible support shaft 30.

[0038] For a single crystal furnace, heater design is one of the core elements of the thermal field design. Heaters are divided into edge ring heaters and bottom heaters. The edge ring heaters provide the primary heat output for the single crystal furnace, playing a crucial role in both the polysilicon melting stage and the subsequent body stage. Their shape and the size of the heating area directly impact the temperature field of the crystal pulling furnace, and thus the quality of the ingot. In this embodiment, multiple heating units 1 are arranged around the edge of the insulating chassis 2, representing the edge ring heaters.

[0039] The insulating connection assembly can move up and down with the crucible support shaft 30, thereby driving the conductive block 4 to move up and down, so as to change the connection position of the conductive block 4 and the corresponding heating unit 1, thereby changing the length of the heating zone of the heating unit 1 in the axial direction of the crucible support shaft 30, which can improve the uniformity of the axial temperature gradient of the crystal rod, and thus realize the adjustment of the oxygen content of crystal rods of different lengths in the crystal pulling equal diameter stage, and realize precise control of the oxygen content. At the same time, during the growth process of the crystal rod, as the length of the crystal rod increases, the length of the heating zone is adjusted to reduce the change in the relative position between the heating zone and the crystal rod in the axial direction of the crystal rod, thereby ensuring that the growth environment of the solid, liquid and gas triple points during crystal growth is always the best growth environment, thereby realizing the controllable crystal defects inside the crystal rod and growing a defect-free crystal rod without micro-defects.

[0040] It should be noted that during the ingot pulling process, as the ingot length increases, the amount of molten silicon decreases. To maintain the same solidification rate, the molten silicon needs to be maintained at the same temperature. However, different volumes of molten silicon require different amounts of heat to maintain the same temperature. Obviously, to maintain the same temperature, a smaller amount of molten silicon requires more heat. In this case, the heating power of the heating unit needs to be increased. However, simply increasing the heating power of the heating unit changes the temperature of the ingot growth environment, causing fluctuations in the solid-liquid interface and leading to uneven ingot growth. In this embodiment, by adjusting the length of the heating zone, that is, reducing the length of the heating zone as the ingot length increases during the crystal pulling process, heat is concentrated in the area corresponding to the molten silicon. By adjusting the power of the heating unit, the temperature of the molten silicon is maintained constant, ensuring the uniformity of the oxygen content of the ingot and the constant heat of the thermal field environment within the single crystal furnace. This ensures that the growth environment at the solid-liquid-gas triple point during crystal growth is always the optimal growth environment, thereby achieving controllable crystal defects within the ingot and growing a defect-free ingot without bulk micro-defects.

[0041] Figure 4 is a schematic diagram of the oxygen content during the crystal rod pulling process, where the horizontal axis is the length of the crystal rod, and the vertical axis is the oxygen content at the corresponding axial position of the crystal rod. The curve labeled 100 is the change in the oxygen content of the crystal rod with the increase in the length of the crystal rod in the traditional technical solution with a constant hot zone. The curve labeled 200 is the change in the oxygen content of the crystal rod with the increase in the length of the crystal rod and the reduction of the length of the heating zone in this embodiment. Comparing the two curves, it is obvious that by adopting the single crystal furnace heating structure in this embodiment, the length of the heating zone of the heating unit 1 in the axial direction of the crystal rod is changed with the change in the length of the crystal rod, thereby improving the uniformity of the oxygen content of the crystal rod.

[0042] The specific structural form of the heating unit 1 can be set according to actual needs, as long as the conductive block 4 can be synchronously raised and lowered under the drive of the insulating connection component when the crucible support shaft 30 is raised and lowered, the length of the heating zone of the heating unit in the axial direction of the crucible support shaft 30 can be changed.

[0043] In an exemplary embodiment, each of the heating units 1 includes a heating plate 11 .

[0044] In an exemplary embodiment, each of the heating units 1 includes at least two heating plates 11 spaced apart from each other, and at least two of the heating plates 11 in the same heating unit 1 are connected in series.

[0045] The number of the heating plates 11 can be set according to actual needs. In this embodiment, each heating unit 1 includes two heating plates 11, but the present invention is not limited thereto.

[0046] Exemplarily, the number of the heating plates 11 in the plurality of heating units 1 is the same, so as to ensure the uniformity of the temperature to which the crystal rod is subjected in its circumferential direction.

[0047] It should be noted that the heating plate 11 has a first end connected to the insulating chassis 2 and a second end disposed opposite the first end. The heating plate 11 has a first surface facing the crucible support shaft 30. The portion of the first surface between the conductive block 4 and the second end is the heating zone for heating the crucible. The conductive block 4 is capable of moving up and down in the axial direction of the crucible support shaft 30. That is, the movement of the conductive block 4 changes the length of the heating zone in the axial direction of the crucible support shaft 30 and the distance between the heating zone and the bottom of the single crystal furnace. This allows the relative position between the heating zone and the crystal ingot to change in the axial direction of the crystal ingot as the crystal ingot is pulled, thereby improving the uniformity of the axial temperature gradient of the crystal ingot. This allows the oxygen content of crystal rods of different lengths to be adjusted during the crystal pulling and equalizing stage, achieving precise control of the oxygen content. Simultaneously, during the growth of the crystal rod, as the length of the crystal rod increases, the length of the heating zone is adjusted to reduce the change in the relative position between the heating zone and the crystal rod in the axial direction of the crystal rod, thereby ensuring that the growth environment at the solid-liquid-gas triple point during crystal growth is always the optimal growth environment. This allows the controllable crystal defects inside the crystal rod to grow a defect-free crystal rod without bulk micro-defects.

[0048] In an exemplary embodiment, each of the heating units 1 includes a conductive connector 12 disposed at one end away from the insulating chassis 2 , and the conductive connector 12 is connected between two adjacent heating plates 11 .

[0049] When each heating unit 1 includes at least two heating plates 11, the provision of the conductive connector 12 enables the series connection of the multiple heating plates 11 in the same heating unit 1. This ensures that the heating power of the multiple heating plates 11 in the same heating unit 1 is the same, and thus the temperature applied to the crystal ingot by the multiple heating plates 11 in the same heating unit 1 is the same, which is conducive to the uniformity of the temperature of the crystal ingot.

[0050] In order to ensure the uniformity of the temperature to which the crystal rod is subjected in its circumferential direction, the distance between the conductive connector 12 and the conductive block 4 in the multiple heating units 1 is the same (it should be noted that the distance here refers to: the distance between the conductive connector 12 and the conductive block 4 in the axial direction of the crucible support shaft 30).

[0051] In an exemplary embodiment, each of the heating units 1 includes an adjacent first heating plate and a second heating plate, and the conductive connecting member 12 is a graphite clip, one end of the graphite clip is fixedly connected to the first heating plate, and the other end of the graphite clip cooperates with the slot on the second heating plate.

[0052] The configuration of the graphite clips enables the adjacent first heating plate and the second heating plate to be movably connected, which facilitates the assembly and maintenance of the heating plate 11 .

[0053] It should be noted that the specific structural form of the conductive connector 12 is not limited to the above. For example, one end of multiple heating plates 11 located in the same heating unit 1 can be connected into an integrated structure through the conductive connector 12. For example, multiple heating plates 11 located in the same heating unit 1 and the conductive connector 12 are integrally injection molded.

[0054] Exemplarily, a surface of the conductive connector 12 away from the insulating chassis 2 is flush with an end surface of the heating plate 11 away from the insulating chassis 2 , so as to maximize the area of ​​the heating zone of the heating component.

[0055] It should be noted that when the same heating unit 1 includes more than two heating plates 11, the advantage of the configuration of the graphite clip is more obvious. Therefore, in some embodiments, optionally, the conductive connecting member 12 is a graphite clip.

[0056] In an exemplary embodiment, in the first direction, the thickness of the heating plate 11 gradually decreases along the direction away from the insulating chassis 2, that is, in the radial direction of the crucible support shaft 30, the thickness of the heating plate 11 gradually decreases along the direction away from the insulating chassis 2.

[0057] During the crystal rod pulling process, as the crucible support shaft 30 rises, the conductive block 4 rises accordingly driven by the insulating connection assembly, so that the length of the heating zone of the heating component (the length in the axial direction of the crucible support shaft 30) is reduced, and the heating area of ​​the heating zone is correspondingly reduced, which will cause the problem of insufficient heating of the crucible.

[0058] To avoid insufficient heating due to a reduced heated area, in one embodiment of the present invention, the thickness of the heating plate 11 gradually decreases in the radial direction of the crucible support shaft 30, away from the insulating base plate 2. This means that the conductive cross-sectional area of ​​the heating plate 11 gradually decreases in the vertical direction (i.e., the axial direction of the crucible support shaft 30). According to the resistance formula R = ρL / S (where ρ is the resistivity, L is the conductive length, i.e., the length between the end of the heating plate 11 away from the insulating base plate 2 and the conductive block 4, and S is the conductive cross-sectional area), L gradually decreases as the conductive block 4 is extended. By appropriately reducing S, the resistance and power are kept stable, avoiding insufficient heating.

[0059] For example, in the radial direction of the crucible support shaft 30 , the thickness of the heating plate 11 is 20-30 mm, but the present invention is not limited thereto.

[0060] In one embodiment, the thickness of the end of the heating plate 11 connected to the insulating chassis 2 in the radial direction of the crucible support shaft 30 is 30 mm, and the thickness of the end of the heating plate 11 away from the insulating chassis 2 in the radial direction of the crucible support shaft 30 is 20 mm, but the present invention is not limited thereto.

[0061] 2 , exemplarily, in the initial state, that is, when the crystal rod is not pulled or is initially pulled, along the axial direction of the crucible support shaft 30, the heating component includes a first part 101 and a second part 102, the orthographic projection of the crucible support shaft 30 on the heating component is located at the first part 101, and the orthographic projection of the crucible on the heating component is located at the second part 102, and in the radial direction of the crucible support shaft 30, along the direction away from the insulating chassis 2, the thickness of the first part 101 remains unchanged, and in the radial direction of the crucible support shaft 30, along the direction away from the insulating chassis 2, the thickness of the second part 102 gradually decreases.

[0062] In the axial direction of the crucible support shaft 30, the second portion 102 is closest to the crucible, and the second portion 102 plays a major role in heating the crucible. Therefore, as the crucible rises along the crucible support shaft 30, the thickness of the second portion gradually decreases in the radial direction of the crucible support shaft 30, away from the insulating chassis 2, thereby ensuring stable resistance and power and avoiding the problem of insufficient heating.

[0063] Exemplarily, the heating plate 11 is made of graphite.

[0064] In an exemplary embodiment, the insulating connection assembly includes an insulating bearing sleeve 8 and a connecting component connected between the conductive block 4 and the insulating bearing sleeve 8. The insulating bearing sleeve 8 is transmission-connected to the crucible support shaft 30, so that the insulating connection assembly rises and falls synchronously with the crucible transmission shaft, and does not rotate with the crucible support shaft 30 when the crucible support shaft 30 rotates.

[0065] 3 , illustratively, the insulating bearing sleeve 8 includes a main shaft sleeve 81 and a secondary shaft sleeve 82, and the secondary shaft sleeve 82 is connected to the crucible support shaft 30 by interference fit. The main shaft sleeve 81 and the secondary shaft sleeve 82 cooperate with each other so that the insulating connection assembly as a whole moves up and down with the lifting and lowering of the crucible support shaft 30. However, when the crucible support shaft 30 rotates, as long as the crucible support shaft 30 rotates alone, the insulating connection assembly as a whole does not rotate.

[0066] In an exemplary embodiment, the insulating connection assembly includes an insulating connection portion and a connection component connected between the conductive block 4 and the insulating bearing sleeve 8. The crucible support shaft 30 includes a rotating shaft and a lifting shaft sleeved outside the rotating shaft. The insulating connection portion is fixedly connected to the outer circumference of the lifting shaft. Therefore, when the lifting shaft drives the crucible to rise and fall, the insulating connection assembly as a whole moves up and down along with the crucible support shaft 30. The lifting shaft and the rotating shaft are connected by a bearing, so that when the rotating shaft drives the crucible to rotate, the lifting shaft remains stationary relative to the rotating shaft, that is, the lifting shaft does not rotate with the rotating shaft. In this case, the insulating connection assembly as a whole does not rotate.

[0067] In an exemplary embodiment, the connecting component includes:

[0068] a first insulating ring 5 , wherein the conductive block 4 is connected to the outer circumference of the first insulating ring 5 ;

[0069] The second insulating ring 7 is sleeved inside the first insulating ring 5 and fixedly connected to the outside of the insulating bearing sleeve 8;

[0070] A plurality of connecting rods 6 are connected between the first insulating ring 5 and the second insulating ring 7 .

[0071] Exemplarily, the plurality of conductive blocks 4 are evenly distributed on the outer circumference of the first insulating ring 5 .

[0072] Exemplarily, a threaded hole is provided on the outer circumferential surface of the first insulating ring 5 , and the conductive block 4 is screwed onto the first insulating ring 5 through the threaded hole.

[0073] Exemplarily, the plurality of connecting rods 6 are evenly distributed between the first insulating ring 5 and the second insulating ring 7 , serving to enhance the overall strength and connection stability of the insulating assembly, thereby facilitating the movement of the conductive block 4 in the axial direction of the crucible support shaft 30 .

[0074] Exemplarily, the conductive block 4 is a trapezoidal structure, and the length of one end of the conductive block 4 close to the first insulating ring 5 is smaller than the length of one end of the conductive block 4 away from the first insulating ring 5 .

[0075] In an exemplary embodiment, the power supply unit includes a positive electrode pin and a negative electrode pin, each of which is connected to a different heating unit. Each of the electrode pins 3 (including the positive electrode pin and the negative electrode pin) is provided with a threaded hole for connecting to an electrode.

[0076] An embodiment of the present application also provides a single crystal furnace, comprising the above-mentioned single crystal furnace heating structure, and also comprising a crucible and a crucible support shaft 30 supporting the crucible, wherein the insulating connection assembly of the single crystal furnace heating device is connected to the crucible support shaft 30.

[0077] Referring to FIG2 , the single crystal furnace further includes:

[0078] furnace body;

[0079] A furnace cover provided on the furnace body;

[0080] A crucible assembly is provided in the inner cavity of the furnace body, wherein the crucible assembly comprises a quartz crucible 10 and a graphite crucible 20 arranged in a sleeve, wherein the quartz crucible 10 contains a silicon solution;

[0081] The single crystal furnace further includes a water cooling device, which includes a water cooling jacket and a lifting structure for controlling the lifting of the water cooling jacket.

[0082] The lifting structure passes through the furnace cover to be connected to the water-cooling jacket, and controls the water-cooling jacket to be suspended above the silicon melt;

[0083] A guide tube is sleeved on the outside of the water cooling jacket, with a gap between the guide tube and the water cooling jacket;

[0084] A heating component is provided around the crucible assembly and is used to heat the crucible assembly. The heating component is fixed to the bottom of the furnace body through electrode bolts and is connected to the heating electrode at the bottom of the furnace body.

[0085] a heat-insulating layer, disposed between the heating component and the side wall of the furnace body, for preventing the heat of the heating component from radiating to the outside of the furnace body;

[0086] The crucible support shaft 30 is supported and connected to the bottom of the graphite crucible 20 through the crucible tray 40 ; the upper end of the crucible support shaft 30 is provided with a crucible tray, and the lower end of the crucible support shaft 30 passes through the bottom of the furnace body.

[0087] With the needs of advanced chip manufacturing processes, there are very strict requirements on the oxygen content and defects in wafers, which puts higher requirements on the oxygen content and defects in crystal rods. The oxygen content in the crystal rod mainly comes from the reaction between the quartz crucible and the silicon solution. The reaction rate of this reaction is mainly affected by the hot zone of the heater. Therefore, the present application also discloses a crystal pulling process method, which adjusts the hot zone of the heater to adjust the oxygen content of crystal rods of different lengths during the crystal pulling equal diameter stage to achieve precise control of the oxygen content. At the same time, by adjusting the hot zone of the heater at different crystal rod lengths, it is ensured that the growth environment of the solid, liquid and gas triple points during crystal growth is always the optimal growth environment, thereby achieving controllable crystal defects inside the crystal rod and growing defect-free crystal rods without micro-defects.

[0088] The following describes the process of crystal pulling using the above-mentioned single crystal furnace:

[0089] First, the crystal raw material is placed in the crucible assembly and melted by the high temperature generated by the heating component.

[0090] Then, the molten silicon solution is slightly cooled to produce a certain degree of supercooling.

[0091] Then, a silicon single crystal (called a seed crystal) fixed on the seed crystal axis is inserted into the melt surface. After the seed crystal and the melt are melted, the seed crystal is slowly pulled upward, and the crystal will grow at the lower end of the seed crystal.

[0092] Next, the seed crystal is controlled to grow a thin neck with a length of about 100 mm and a diameter of 3 mm to 5 mm to eliminate the dislocation of atomic arrangement caused by the strong thermal shock of the high-temperature solution on the seed crystal. This process is called seeding.

[0093] Subsequently, the crystal diameter is enlarged to the size required by the process, generally 75mm to 300mm. This process is called shouldering.

[0094] Then, suddenly increase the pulling speed to rotate the shoulder so that the shoulder is approximately at a right angle.

[0095] Then, the equal-diameter process is entered, and single crystal columns of a certain size are grown by controlling the thermal field temperature and the crystal lifting speed.

[0096] Finally, when most of the silicon solution has completed crystallization, the crystals are gradually shrunk to form a tail-shaped cone, which is called the finishing process.

[0097] In this way, the single crystal pulling process is basically completed and can be taken out after a certain period of insulation and cooling.

[0098] As shown in Figures 1 and 2, the single crystal furnace heating structure disclosed in the embodiment of the present application, the heating zone of the heating component is the area between the conductive connector 12 and the conductive block 4 on the heating plate 11. During the material charging stage of the crystal pulling process, the conductive block 4 is located on the side of the heating unit 1 close to the insulating chassis 2. At this time, the distance from the bottom of the conductive connector 12 to the upper end face of the conductive block 4 is the largest, the area of ​​the heating zone is the largest, and the length of the heating zone in the axial direction of the crucible support shaft 30 is also the largest. The heat generated by the heating component will be evenly transmitted to the crucible assembly and the silicon material contained in the crucible assembly, achieving uniform charging, preventing the phenomenon of local expansion of the quartz crucible caused by uneven heating, and achieving rapid charging. During the crystal rod equal diameter growth stage, according to the continuous reduction of the amount of silicon solution in the quartz crucible, the crucible support shaft 30 rises, thereby causing the conductive block 4 to rise, reducing the length of the heating zone in the axial direction of the crucible support shaft 30, and also reducing the area of ​​the heating zone, ensuring that the crystal rod is always grown under a suitable temperature field.

[0099] The resistance formula is R=ρL / S, where ρ is the resistivity, which is a fixed value, L is the conductive length, and S is the conductive cross-sectional area. According to the above resistance formula, the resistivity is a fixed value, and the size of the resistance is related to the conductive length L and the conductive cross-sectional area S. As the conductive block 4 rises, the conductive length of the heating zone decreases. Although the conductive cross-sectional area S also decreases, the ratio of L to S increases, that is, the resistance increases. At this time, in order to avoid insufficient heating due to the reduction of the heating zone, the conductive cross-sectional area of ​​the heating plate 11 (the heating plate 11 includes a first surface facing the crucible and a second surface adjacent to the first surface. The conductive cross-sectional area of ​​the heating plate 11 is the area of ​​the portion of the second surface located between the conductive connector 12 and the conductive block 4) gradually decreases in the vertical direction (that is, the axial direction of the crucible support shaft 30). As the conductive block moves upward, L gradually decreases. By appropriately reducing S, the resistance and power are guaranteed to be stable, and the problem of insufficient heating is avoided.

[0100] It is understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present application, and the present application is not limited thereto. Those skilled in the art may make various modifications and improvements without departing from the spirit and substance of the present application, and such modifications and improvements are also considered to be within the scope of protection of the present application.

Claims

1. A single crystal furnace heating structure, comprising: Insulated chassis; A plurality of heating units, wherein the plurality of heating units are disposed around the edge of the insulating chassis; a power supply unit, used for applying an electrical signal to the heating unit; A conductive block, movably connected between adjacent heating units, so that a plurality of the heating units are connected in series, and cooperates with the power supply unit to form a loop; An insulating connection component, one end of which is connected to the conductive block, and the other end of which is used to connect to the crucible support shaft. The insulating connection component moves up and down as the crucible support shaft rises and falls, thereby driving the conductive block to move up and down to change the length of the heating zone of the heating unit in a first direction, where the first direction is the axial direction of the crucible support shaft.

2. The single crystal furnace heating structure according to claim 1, wherein: Each of the heating units comprises at least two heating plates arranged at intervals, and at least two of the heating plates in the same heating unit are connected in series.

3. The single crystal furnace heating structure according to claim 1, wherein: Each of the heating units includes a heating plate.

4. The single crystal furnace heating structure according to claim 3, wherein: Each of the heating units includes a conductive connecting member disposed at one end away from the insulating chassis, and the conductive connecting member is connected between two adjacent heating plates.

5. The single crystal furnace heating structure according to claim 4, wherein: The conductive connecting piece is a graphite clip.

6. The single crystal furnace heating structure according to claim 2 or 3, wherein: In the first direction, along the direction away from the insulating chassis, the thickness of each heating plate gradually decreases.

7. The single crystal furnace heating structure according to claim 1, wherein: The insulating connection assembly includes an insulating bearing sleeve and a connecting component connected between the conductive block and the insulating bearing sleeve. The insulating bearing sleeve is transmission-connected to the crucible support shaft, so that the insulating connection assembly rises and falls synchronously with the crucible support shaft, and does not rotate with the crucible support shaft when the crucible support shaft rotates.

8. The single crystal furnace heating structure according to claim 7, wherein: The connecting component comprises: A first insulating ring, wherein the conductive block is connected to an outer peripheral surface of the first insulating ring; A second insulating ring is sleeved inside the first insulating ring, and the second insulating ring is fixedly connected to the outside of the insulating bearing sleeve; A plurality of connecting rods are connected between the first insulating ring and the second insulating ring.

9. The single crystal furnace heating structure according to claim 7, wherein: The power supply unit includes a positive electrode pin and a negative electrode pin, and the positive electrode pin and the negative electrode pin are respectively connected to different heating units.

10. A single crystal furnace, comprising the single crystal furnace heating structure according to any one of claims 1 to 9, further comprising a crucible and a crucible support shaft supporting the crucible, wherein the insulating connection assembly of the single crystal furnace heating device is connected to the crucible support shaft.

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