A pulling shaft of a single crystal furnace, a pulling device, a single crystal furnace and a crystal pulling method

Abstract

The application relates to the field of semiconductor growth, in particular to a pulling shaft of a single crystal furnace, which is applied to the single crystal furnace and comprises a hard shaft, the hard shaft is in a long straight state and is vertically arranged; a soft shaft, the first end of the soft shaft is connected to the bottom of the hard shaft, and the soft shaft is coaxially arranged with the hard shaft; and a clamp assembly, the clamp assembly is connected to the second end of the soft shaft, and the clamp assembly is used for clamping a seed crystal. The technical problem that the crystal pulling quality is not high is solved, and the technical effect that the crystal quality is improved is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor growth, in particular to a pulling shaft of a single crystal furnace, a pulling device, a single crystal furnace and a crystal pulling method. BACKGROUND

[0002] The Czochralski single crystal silicon growth furnace is the main equipment for preparing single crystal silicon material, also known as a single crystal silicon growth furnace or a single crystal furnace. The equipment melts high-purity polycrystalline silicon raw material in a quartz crucible by graphite heating, and under the protection of continuous low-pressure argon, a silicon crystal is crystallized on a small seed crystal at a suitable temperature and growth rate to form a single crystal. With the development of market demand, the size of silicon single crystal is developing towards large size and large weight.

[0003] In the prior art, the seed crystal is generally connected by a soft shaft, and the seed crystal is gradually pulled upward and grown after being separated from the silicon liquid surface, thereby obtaining a crystal bar. However, since the soft shaft has a certain flexibility, the crystal will sway to different degrees during the crystal pulling process due to vibration or mechanical errors. Crystal sway refers to the motion state of the crystal during the pulling process, which is a single pendulum or conical pendulum. Therefore, the quality of the crystal obtained by such pulling is not high.

[0004] Therefore, the technical problem of the prior art is that the quality of the pulled crystal is not high. SUMMARY

[0005] The present application provides a pulling shaft of a single crystal furnace, a pulling device, a single crystal furnace and a crystal pulling method, which solves the technical problem of low quality of the pulled crystal and achieves the technical effect of improving the quality of the crystal.

[0006] In a first aspect, the present application provides a pulling shaft of a single crystal furnace, which adopts the following technical scheme:

[0007] A pulling shaft of a single crystal furnace is applied in a single crystal furnace, comprising: a hard shaft, which is in a long straight state and is vertically arranged; a soft shaft, a first end of the soft shaft being connected to a bottom of the hard shaft, the soft shaft being coaxially arranged with the hard shaft; and a clamp assembly, which is connected to a second end of the soft shaft and is used for clamping a seed crystal.

[0008] Preferably, the hard shaft comprises: an outer shaft, which has an inner cavity penetrating upward and downward in the interior; and an inner shaft, which is located in the inner cavity of the outer shaft and is coaxially arranged with the outer shaft, the inner shaft and the outer shaft having independent vertical movement freedom and synchronous rotation freedom around the shaft; and the first end of the soft shaft is connected to the bottom of the inner shaft.

[0009] As preferred, the bottom of the inner cavity of the outer shaft has a partition plate, which is fixedly connected to the bottom of the outer shaft or integrally formed with the outer shaft; wherein the first end of the soft shaft penetrates the partition plate from bottom to top, and the first end of the soft shaft is fixed in the inner cavity of the outer shaft.

[0010] As preferred, the two ends of the soft shaft have first limiting parts; the two ends of the soft shaft are respectively provided with connecting assemblies, and the soft shaft is connected with the inner shaft and the clamp assembly through the two groups of connecting assemblies respectively; each group of the connecting assemblies comprises a sleeve for connecting with the inner shaft or the clamp assembly, a channel is arranged on the side wall of the sleeve in a first direction and penetrates the sleeve, the channel can accommodate the soft shaft into the sleeve, and the first limiting part of the soft shaft is limited by abutting against the end of the sleeve. As preferred, the partition plate has a recessed part recessed to the inner cavity of the outer shaft; the top of the clamp assembly has a protruding part corresponding to the recessed part, the protruding part and the recessed part form a first station and a second station when the inner shaft is raised and lowered; when the protruding part is in the first station, the soft shaft is stretched out of the outer shaft, and the protruding part and the recessed part are separated from each other; when the protruding part is in the second station, the soft shaft is retracted into the inner shaft, and the protruding part and the recessed part abut against each other.

[0011] As preferred, the clamp assembly comprises a counterweight connected with the soft shaft, and a clamp connected to the bottom of the counterweight and used for connecting a seed crystal.

[0012] In a second aspect, the application provides a lifting device of a single crystal furnace, which adopts the following technical scheme:

[0013] The lifting device of the single crystal furnace is applied to the single crystal furnace, and comprises a lifting shaft, a driving mechanism connected to and acting on the lifting shaft and used for driving the lifting shaft to rotate and lift.

[0014] As preferred, the driving mechanism comprises a seat body, a first seat, a second seat, a first driving assembly, and a second driving assembly; the seat body comprises the first seat and the second seat; the second seat is movably connected to the first seat and has a vertical movement freedom; the first driving assembly is connected to the second seat and acts on the outer shaft, and is used for driving the outer shaft to rotate, so as to drive the inner shaft to rotate synchronously with the outer shaft; the second driving assembly comprises a first driving member connected to the first seat and acting on the outer shaft, and a second driving member connected to the second seat and acting on the inner shaft, and is used for driving the inner shaft to lift independently.

[0015] In a third aspect, the single crystal furnace provided by the application adopts the technical scheme as follows:

[0016] The single crystal furnace comprises a single crystal furnace body, a pulling device, wherein the pulling device is the pulling device described above, and the pulling device is located at the top of the single crystal furnace body and is used for vertically downwardly entering the single crystal furnace body to pull a crystal bar.

[0017] In a fourth aspect, the pulling method of the single crystal furnace provided by the application adopts the technical scheme as follows:

[0018] The pulling method of the single crystal furnace provided by the application adopts the technical scheme as follows:

[0019] As a preferred, the driving pulling shaft is driven to descend into the single crystal furnace body, and the seed crystal is in contact with the silicon liquid surface; the pulling shaft is driven to rotate and pull, and a fine crystal is formed on the seed crystal; the inner shaft is driven to ascend relative to the outer shaft, and the flexible shaft is retracted into the inner cavity of the outer shaft to reduce the extension length of the flexible shaft; and the pulling growth of the crystal bar is completed.

[0020] In summary, the application has at least one of the following beneficial technical effects:

[0021] 1. The single crystal furnace provided by the application provides a new type of pulling shaft, a flexible shaft is connected to the bottom end of a hard shaft, the hard shaft has rigidity, and the length of the flexible shaft is reduced relative to the conventional long-size flexible shaft pulling scheme, so that the crystal swing amplitude formed by the flexible shaft can be effectively controlled; therefore, the application reduces the amplitude of crystal swing, solves the technical problem of low crystal pulling quality, and achieves the technical effect of improving the crystal quality.

[0022] 2. Since the flexible shaft has flexibility, the vertical state is maintained under the action of the crystal bar, the eccentric error of the hard shaft is reduced, the concentricity of the whole pulling shaft is improved, the technical problem of low crystal pulling quality is solved, and the technical effect of improving the crystal quality is achieved.

[0023] 3. The hard shaft is divided into an outer shaft and an inner shaft and is lifted respectively, the extension length of the flexible shaft is adjusted, the crystal bar swing caused by the single pendulum effect of the flexible shaft is slowed down, and the crystal bar quality is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic diagram of the pulling shaft described in the application;

[0025] Figure 2 is a front view of the pulling shaft described in the application;

[0026] Figure 3 is a schematic diagram of a connecting assembly of the pulling shaft described in the application;

[0027] Figure 4is a flowchart of the crystal pulling method described in the present application;

[0028] Figure 5 is a flowchart of the pulling process of the crystal pulling method described in the present application.

[0029] Reference signs: 100, hard shaft; 110, inner shaft; 120, outer shaft; 121, partition; 122, recess; 200, soft shaft; 210, first limiting part; 220, connecting assembly; 221, sleeve; 222, channel; 223, second limiting part; 300, clamp assembly; 310, counterweight; 311, protrusion; 320, clamp. DETAILED DESCRIPTION

[0030] Herein, the serial numbers for components, such as "first", "second", etc., are merely used to distinguish the described objects, and do not have any sequential or technical meaning. Unless otherwise specified, the terms "connected", "coupled" in the present application include direct and indirect connections (couplings). In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship shown in the drawings, and are merely used for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0031] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only means that the horizontal height of the first feature is less than that of the second feature.

[0032] The pulling shaft of the single crystal furnace, the pulling device, the single crystal furnace and the crystal pulling method provided by the embodiments of the present application solve the technical problem of low crystal pulling quality and achieve the technical effect of improving the quality of the crystal.

[0033] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with the drawings of the specification and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0034] With the development of market demand, the size of silicon single crystal is developing towards large size and large weight, and the crystal quality needs to be guaranteed; in the actual research and development process, the applicant adopts the soft shaft 200 pulling mode for crystal pulling due to the compact structure and strong applicability of the soft shaft 200 growth furnace, but the single crystal furnace using the soft shaft 200 also has some problems: first, due to the limitation of the soft shaft 200 winch mechanism, the flexibility of the tungsten alloy cable needs to be ensured, so the carrying capacity of the soft shaft 200 is further limited, which limits the capacity improvement of a single device; second, the soft shaft 200 lifting, due to the single pendulum mechanism at a certain length of the soft shaft 200, there will be a periodic shaking interval, and the crystal shaking amplitude gradually increases with the increase of its rotating speed, which limits the process window of higher quality crystal growth; third, the soft shaft 200 can only grow the crystal concentrically, and the rotation speed of the crystal interface center point is 0, which is easy to form a defect source; fourth, the tungsten alloy cable gradually moves away from the high temperature zone with the increase of the single crystal length, and its own temperature gradually decreases and shrinks in volume, which makes the crystal growth interface position lifting speed V not equal to the set lifting speed, and the deviation of V makes the precise control of the defect process window smaller; therefore, some problems existing in the soft shaft 200 during the crystal pulling process need to be solved.

[0035] The application provides a pulling shaft of a single crystal furnace, which is applied to a single crystal furnace, and the pulling shaft is used for downward entering the single crystal furnace, such as shown in Figure 1 , the seed crystal connected through the bottom of the pulling shaft is used for pulling crystal, the pulling shaft is vertically arranged, and the pulling shaft comprises a hard shaft 100, a soft shaft 200 and a clamp assembly 300 from top to bottom, the hard shaft 100 is used as a connecting basis of the soft shaft 200; the soft shaft 200 is used as a connecting basis of the clamp assembly 300; and the clamp assembly 300 is used for clamping the seed crystal.

[0036] The hard shaft 100, as shown in Figure 1 , is used as a connecting basis of the soft shaft 200. The hard shaft 100 is located directly above the soft shaft 200, the hard shaft 100 is in a long straight cylindrical shape and is vertically arranged.

[0037] Further, as shown in Figure 2As shown, the hard shaft 100 comprises an outer shaft 120 and an inner shaft 110, the outer shaft 120 is tubular, and the inner shaft 110 is accommodated in the inner cavity of the outer shaft 120, and the inner shaft 110 and the outer shaft 120 are coaxially arranged, and the inner shaft 110 and the outer shaft 120 have independent movement freedom, and the inner shaft 110 and the outer shaft 120 have rotation freedom that can be rotated synchronously, specifically, the inner shaft 110 and the outer shaft 120 can be relatively moved, that is, the inner shaft 110 can be independently vertically lifted relative to the outer shaft 120, in other words, the outer shaft 120 can also be independently vertically lifted relative to the inner shaft 110; and the inner shaft 110 and the outer shaft 120 have a synchronous structure, so that the outer shaft 120 rotates around the shaft at the same time, and can drive the inner shaft 110 to rotate synchronously, in an embodiment, the inner shaft 110 has a section of square rod area, the cross section of the inner shaft 110 of the square rod area is a square, and correspondingly, the inner wall of the outer shaft 120 has a section of square cavity, the cross section of the inner wall of the square cavity is a square corresponding to the square rod area, the square rod area cooperates with the square cavity, in this way, the inner shaft 110 can rotate the same as the outer shaft 120 through the synchronous structure when the outer shaft 120 rotates, and does not affect the independent lifting action of the inner shaft 110 and the outer shaft 120.

[0038] Further, as shown in Figure 1 The bottom of the outer shaft 120 is connected with a partition plate 121, the partition plate 121 is used to close the bottom end of the outer shaft 120 to improve the heat insulation protection of the internal structure of the outer shaft 120, in an embodiment, the partition plate 121 is fixedly connected to the bottom end of the outer shaft 120, so that the bottom end of the outer shaft 120 is closed by the partition plate 121; in other embodiments, the partition plate 121 is formed integrally with the bottom end of the outer shaft 120, and the bottom end of the outer shaft 120 is also closed by the partition plate 121; a perforation is formed on the partition plate 121, and the perforation is used for the penetration of the soft shaft 200, and it is worth noting that the position of the perforation is located on the rotation center of the hard shaft 100.

[0039] The soft shaft 200, as shown in Figure 2 , 3As shown, the soft shaft 200 is used as the connecting base of the clamp assembly 300. The first end of the soft shaft 200 is connected to the hard shaft 100, and the second end of the soft shaft 200 is connected to the clamp assembly 300, specifically, the first end of the soft shaft 200 is connected to the bottom of the hard shaft 100, and the soft shaft 200 is coaxially arranged with the hard shaft 100 to reduce the problem of different crystals in the crystal pulling process and reduce the quality of the crystal; in one embodiment, when the hard shaft 100 is a long straight integrated cylindrical shape, the soft shaft 200 is directly connected to the bottom of the hard shaft 100; in other embodiments, when the hard shaft 100 includes an inner shaft 110 and an outer shaft 120 that can be independently lifted and synchronously rotated, the soft shaft 200 is connected to the bottom end of the inner shaft 110, specifically, the soft shaft 200 is connected to the clamping mechanism by being threaded through the perforation on the partition plate 121 from one end connected to the bottom end of the inner shaft 110. The soft shaft 200 has a certain flexibility, and in one embodiment, the soft shaft 200 is made of tungsten wire rope.

[0040] As shown, the clamp assembly 300 is used to clamp the seed crystal. Figure 2 、 3 The clamping mechanism is connected to the second end of the soft shaft 200, that is, the bottom of the soft shaft 200, and includes a counterweight 310 and a clamp 320. The counterweight 310 is used for counterweighting the soft shaft 200 and simultaneously serving as the connecting base of the clamp 320. The clamp 320 is used to clamp the seed crystal. The counterweight 310 is connected to the bottom end of the soft shaft 200, and the clamp 320 is connected to the counterweight 310. It is worth noting that the counterweight 310 and the clamp 320 are centrally symmetrically arranged and coaxially arranged with the hard shaft 100; in one embodiment, the clamp 320 specifically adopts a graphite chuck to clamp the seed crystal.

[0041] Further, as shown, Figure 2 、 3As shown, the first limiting part 210 is larger in volume than the soft shaft 200, and in an embodiment, the first limiting part 210 is a limiting ball connected to the two ends of the soft shaft 200. Further, the soft shaft 200 is provided with a connecting assembly 220, and specifically, the connecting assembly 220 has two groups, and the two groups of connecting assemblies are respectively arranged at the two ends of the soft shaft 200, that is, the two ends of the soft shaft 200 are respectively connected to the inner shaft 110 and the clamp assembly 300 through the connecting assembly 220. The two groups of connecting assemblies 220 are the same in structure, and in the embodiment, only one group of connecting assemblies 220 is taken as an example to be described. The connecting assembly 220 includes a sleeve 221, the sleeve 221 is hollow and penetrates through the two ends of the sleeve 221, a channel 222 is formed in the side wall of the sleeve 221, the channel 222 is arranged in a first direction, and specifically, the direction of the channel 222 is parallel to the axial direction of the sleeve 221. The channel 222 is arranged to make the internal space of the sleeve 221 communicate with the external space, and the channel 222 is formed in the side wall of the sleeve 221 and penetrates through the two ends of the sleeve 221 in the length direction. Further, the sleeve 221 has a second limiting part 223 at one end, so that the soft shaft 200 enters the sleeve 221 through the channel 222, and the first limiting part 210 of the soft shaft 200 and the second limiting part 223 at the end of the sleeve 221 are matched with each other to limit the soft shaft 200, at this time, the lifting shaft forms a pure hard shaft to be lifted. In the connecting assembly 220 at the upper end of the soft shaft 200, the sleeve 221 is fixedly connected to the bottom end of the inner shaft 110. In the connecting assembly 220 at the lower end of the soft shaft 200, the sleeve 221 is fixedly connected to the top of the clamping mechanism, and specifically, the sleeve 221 is fixedly connected to the top of the counterweight 310, so that the soft shaft 200 is connected to the hard shaft 100 and the clamp assembly 300 respectively.

[0042] Further, as shown in Figure 2 、 3 , the bottom of the inner shaft 110 has a transition section, the transition section is connected to the soft shaft 200 through the connecting assembly 220 at the top of the soft shaft 200, and specifically, the sleeve 221 of the connecting assembly 220 is connected to the bottom of the transition section. The transition section has a cavity in the inside, so that the soft shaft 200 has a space to move upward. Correspondingly, the counterweight 310 is connected to the soft shaft 200 through the connecting assembly 220, and specifically, the sleeve 221 of the connecting assembly 220 is connected to the top of the counterweight 310. The counterweight 310 also has a cavity in the inside, so that the soft shaft 200 has a space to move downward.

[0043] The bottom of the hard shaft 100 and the top of the clamp assembly 300 are provided with a matching structure, as shown in Figure 2 、 3As shown, specifically, the matching structure is arranged at the bottom of the outer shaft 120 and the top of the counterweight 310, and the matching structure includes a recess 122 and a protrusion 311. The recess 122 is arranged below the partition plate 121 at the bottom of the outer shaft 120, and the bottom of the outer shaft 120 is formed with the recess 122 by opening a chamfer inwardly. The protrusion 311 is arranged at the top of the counterweight 310, and the top of the counterweight 310 is formed with the protrusion 311 by opening a chamfer at the edge of the top of the counterweight 310. It is worth noting that the recess 122 and the protrusion 311 match each other, in other words, the shape and size of the inwardly recessed recess 122 are consistent with the shape and size of the outside of the protrusion 311, so that the protrusion 311 at the top of the counterweight 310 can be exactly accommodated in the recess 122. The protrusion 311 and the recess 122 form a first station and a second station as the inner shaft 110 rises and falls. When in the first station, the soft shaft 200 extends outside the outer shaft 120, and the protrusion 311 and the recess 122 are separated from each other. When in the second station, the soft shaft 200 is retracted into the inner shaft 120, and the protrusion 311 and the recess 122 are in contact with each other. Specifically, the inner shaft 110 is driven upward to move, so that the soft shaft 200 is driven to retract into the inner cavity of the outer shaft 120. At this time, the clamp assembly 300 is synchronously moved upward by the soft shaft 200, so that the protrusion 311 enters the recess 122 to form a match, thereby forming an integral body between the clamp assembly 300 and the hard shaft 100 to reduce the crystal flicker.

[0044] The application also provides a lifting device of a single crystal furnace, which is applied to the single crystal furnace and used for lifting a shaft to downwardly enter the single crystal furnace to perform crystal pulling by a seed crystal connected to the bottom of the shaft. The lifting device comprises the shaft and a driving mechanism. The shaft is vertically arranged and used for downwardly entering the single crystal furnace to perform crystal pulling. The driving mechanism is used for driving the shaft to rotate and lift.

[0045] The shaft, as shown in the figure, is used for downwardly entering the single crystal furnace to perform crystal pulling. The shaft is arranged at the top of the single crystal furnace and is vertically arranged. The specific structure of the shaft is the same as that of the shaft described above, which will not be repeated here. Figures 1-4

[0046] The driving mechanism, which is not shown in the figure, is used for driving the shaft to rotate and lift. The driving mechanism is arranged at the top of the single crystal furnace and acts on and drives the shaft. The driving mechanism comprises a seat body, a first driving assembly and a second driving assembly. The seat body is used as a mounting and bearing basis of the first driving assembly and the second driving assembly. The first driving assembly is used for driving the shaft to rotate. The second driving assembly is used for driving the shaft to lift.

[0047] ​The seat body is used as a mounting bearing base of the first driving assembly and the second driving assembly. The seat body comprises a first seat and a second seat. The first seat is relatively fixed and is arranged above the single crystal furnace through the frame. The second seat is slidably connected to the first seat and can vertically slide relative to the first seat. In an embodiment, the second seat is slidably connected to the first seat through a vertically arranged slide rail.

[0048] The first driving assembly is used to drive the rotation of the pulling shaft. The first driving assembly is located on the second seat and can ascend and descend with the second seat. It is worth noting that the outer shaft 120 is rotatably connected to the second seat through a bearing, so that the outer shaft 120 can rotate under the action of the first driving assembly and can also ascend and descend with the second seat. Specifically, the first driving assembly comprises a first motor and a first synchronous belt. The first motor is connected to the second seat, and the first synchronous belt is drivingly connected to the output shaft of the first motor and the outside of the outer shaft 120, so that the first motor can drive the outer shaft 120 to rotate.

[0049] The second driving assembly is used to drive the lifting of the pulling shaft. The second driving assembly comprises a first driving member and a second driving member. The first driving member is used to drive the lifting of the pulling shaft as a whole. The second driving member is used to drive the independent lifting of the inner shaft 110.

[0050] The first driving member is used to drive the lifting of the pulling shaft as a whole. The first driving member is connected to the first seat. The first driving member comprises a lead screw, a sliding block, a second motor and a second synchronous belt. The lead screw is arranged in a vertical direction and is rotatably connected to the first seat. The sliding block is threadedly connected to the lead screw and is fixedly connected to the second seat. The second motor is connected to the first seat and acts on the lead screw. Specifically, the second synchronous belt is drivingly connected between the output end of the second motor and the lead screw, so that the second motor can drive the rotation of the lead screw. In this way, the second motor drives the rotation of the lead screw, the sliding block slides along the direction of the lead screw, the second seat is slidably connected to the first seat through the slide rail, and the second seat and the pulling shaft as a whole vertically ascend and descend under the guidance of the slide rail.

[0051] The second driving member is used to drive the independent lifting of the inner shaft 110. The second driving member is connected to the top of the pulling shaft. The second driving member comprises a pneumatic cylinder. The pneumatic cylinder is connected to the second seat and is coaxially arranged with the pulling shaft. The output rod of the pneumatic cylinder is connected to the top of the inner shaft 110 through a universal joint, so that the pneumatic cylinder can drive the lifting of the inner shaft 110, thereby realizing the independent lifting of the inner shaft 110 while the pulling shaft as a whole is lifted.

[0052] Thus, the first driving mechanism drives the pulling shaft to rotate to meet the crystal pulling requirement; the first driving member in the second driving mechanism drives the pulling shaft to ascend and descend as a whole, first, the first driving member drives the pulling shaft to descend into the interior of the single crystal furnace, the crystal is first adsorbed on the seed crystal to complete the growth of the fine crystal, with the pulling shaft being pulled upward by the first driving member, the crystal bar is gradually formed, in the pulling process, the length of the soft shaft 200 is adjusted by the second driving member driving the inner shaft 110 to ascend or descend relative to the outer shaft 120 while the pulling shaft is pulled as a whole, with the first driving member being further pulled, the growth of the crystal bar is completed.

[0053] The application further provides a single crystal furnace, which is used for crystal growth and obtains a silicon single crystal by pulling in a molten silicon material, and comprises a single crystal furnace body and a pulling device, wherein the single crystal furnace body serves as the main body for crystal growth; and the pulling device is used for pulling a crystal bar.

[0054] The single crystal furnace body, not shown in the figure, serves as the main body for crystal growth. The single crystal furnace body comprises a main furnace chamber and a sub-furnace chamber, the main furnace chamber has a crucible, a heater and the like for providing a structure for crystal growth, and the sub-furnace chamber is connected to the top of the main furnace chamber and communicates with the main furnace chamber. Here, the single crystal furnace body is a device for growing a crystal bar for photovoltaic or semiconductor, and the structure thereof will not be further described.

[0055] The pulling device, as shown in Figures 1-4 , is used for pulling a crystal bar. The structure of the pulling device is the same as that of the above-mentioned pulling device, and will not be described again here; it is worth noting that the pulling device is located at the top of the single crystal furnace body and is used for downwardly entering the single crystal furnace body to pull a crystal, and the pulling device is connected by a rack to be erected at the top of the single crystal furnace body. Specifically, the first seat is fixedly connected to the rack, so that the pulling shaft has an execution station capable of downwardly entering the interior of the single crystal furnace body or upwardly pulling from the interior of the single crystal furnace body.

[0056] The application further provides a crystal pulling method using the above-mentioned pulling device, as shown in Figure 4 , which comprises the following steps.

[0057] S100: first driving the pulling shaft to descend so that the seed crystal on the clamp 320 is in contact with the silicon liquid surface;

[0058] S200: the pulling shaft is pulled upward while being rotated by the driving mechanism;

[0059] S300: thereby obtaining a crystal bar.

[0060] Specifically, as shown in Figure 5 , S200: the pulling shaft is pulled upward while being rotated by the driving mechanism, which comprises the following steps.

[0061] S210: drive the pulling shaft to rotate and pull, and form a fine crystal on the seed crystal;

[0062] S220: drive the inner shaft 110 to ascend relative to the outer shaft 120, and drive the soft shaft 200 to retract into the inner cavity of the outer shaft 120 to reduce the extension length of the soft shaft 200.

[0063] Adjust the length of the soft shaft 200 according to the pulling step, for example, as shown in the following figure, which includes the following stages: Figure 5

[0064] First stage:

[0065] The pulling shaft is in the first state, in which the soft shaft 200 is retracted in the inner part of the outer shaft 120, so that the clamp assembly 300 and the bottom of the outer shaft 120 are in contact to form an integral whole; the first driving member drives the pulling shaft to descend into the inner part of the single crystal furnace body as a whole;

[0066] Second stage:

[0067] With the first driving member driving the pulling shaft to descend until the seed crystal reaches the first length above the silicon liquid surface, the pulling shaft is switched from the first state to the second state, in which the second driving member drives the inner shaft 110 to descend, and the soft shaft 200 gradually extends out of the inner cavity of the outer shaft 120, until the soft shaft 200 reaches the maximum length, and at this time the seed crystal is in contact with the silicon liquid surface; wherein the first length is the length of the soft shaft 200; after the pulling shaft is lowered to the lowest position, the soft shaft 200 is driven to extend out, so as to reduce the shaking of the soft shaft 200 caused by errors or shaking during the descent of the hard shaft 100;

[0068] Third stage:

[0069] The pulling shaft is in the second state, the first driving assembly drives the pulling shaft to rotate as a whole, the first driving member drives the outer shaft 120 to ascend as a whole at a pulling speed V, and the remaining temperature and other factors meet the requirements of the crystal growth process, the silicon material is gradually adsorbed on the seed crystal until a fine crystal of 400mm-500mm is formed to eliminate the dislocation between the crystals; through the flexibility of the soft shaft 200, the fine crystal and the pulling shaft are in a concentric state, the tangential stress during crystal growth is reduced, and the crystal growth is prevented from being broken;

[0070] Fourth stage:

[0071] ​With the lifting of the pulling shaft, fine crystals grow on the seed crystal, and after the shoulder is put, the crystal of equal diameter is obtained, the equal diameter crystal rod drawing is started, and with the increase of the weight of the equal diameter crystal rod, the trend of the influence of the increase of the weight of the crystal rod on the swing of the soft shaft 200 gradually increases during the high-speed rotation process, the second driving member drives the inner shaft 110 to lift at a lifting speed of a, the first driving member drives the outer shaft 120 to lift at a speed of V-a, so that the lifting speed of the crystal is kept as V, the length of the soft shaft 200 is gradually reduced, and the soft shaft 200 is fully retracted into the inner cavity of the outer shaft 120, so that the clamp assembly 300 and the bottom of the outer shaft 120 are in contact to form an integral whole, that is, the pulling shaft is switched from the second state back to the first state; thereby reducing the crystal swing influence on the quality of the crystal drawing.

[0072] Working principle / steps:

[0073] The pulling shaft is lowered into the single crystal furnace body, the soft shaft 200 is in the extended state for fine crystal growth, after the shoulder is put, the soft shaft 200 is retracted into the inner cavity of the outer shaft 120, the length of the soft shaft 200 is reduced, and the crystal rod is obtained after the crystal rod is grown to equal diameter.

[0074] Technical effects:

[0075] 1. The single crystal furnace in the application provides a new type of pulling shaft, which is connected with a soft shaft 200 at the bottom end of a hard shaft 100, the hard shaft 100 has rigidity, and the length of the soft shaft 200 is reduced compared with the traditional long-size soft shaft 200 pulling scheme, and the crystal swing amplitude caused by the soft shaft 200 can be effectively controlled; therefore, the application reduces the amplitude of crystal swing, solves the technical problem of low crystal drawing quality, and achieves the technical effect of improving the quality of the crystal.

[0076] 2. Since the soft shaft 200 has flexibility, it remains vertical under the action of the crystal rod, reduces the eccentric error of the hard shaft 100, and improves the concentricity of the whole pulling shaft, thereby solving the technical problem of low crystal drawing quality and achieving the technical effect of improving the quality of the crystal.

[0077] 3. The hard shaft 100 is divided into an outer shaft 120 and an inner shaft 110, which are lifted respectively, the extension length of the soft shaft 200 is adjusted, the crystal rod swing caused by the single pendulum effect of the soft shaft 200 is slowed down, and the quality of the crystal rod is further improved.

[0078] Although the preferred embodiments of the application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic creative concept. Therefore, the appended claims are intended to include the preferred embodiments and all changes and modifications falling within the scope of the application.

[0079] Obviously, many modifications and variations of the present application are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A pulling shaft for a single crystal furnace, used in a single crystal furnace, characterized in that, include: A rigid shaft (100) is long and straight and is arranged vertically; A flexible shaft (200) is provided, the first end of which is connected to the bottom of the rigid shaft (100), and the flexible shaft (200) and the rigid shaft (100) are coaxially arranged. as well as A clamping assembly (300) is connected to the second end of the flexible shaft (200) and is used to clamp the seed crystal.

2. The pulling shaft of a single crystal furnace according to claim 1, characterized in that, The rigid shaft (100) includes: An outer shaft (120) has a through-cavity inside. An inner shaft (110) is located inside the cavity of the outer shaft (120), and the inner shaft (110) and the outer shaft (120) are coaxially arranged. The inner shaft (110) and the outer shaft (120) have independent vertical degrees of freedom of movement, and the inner shaft (110) and the outer shaft (120) have synchronous rotational degrees of freedom of rotation around the axis. The first end of the flexible shaft (200) is connected to the bottom of the inner shaft (110).

3. The pulling shaft of a single crystal furnace according to claim 2, characterized in that, The bottom of the inner cavity of the outer shaft (120) has a partition (121), which is fixedly connected to the bottom of the outer shaft (120) or integrally formed with the outer shaft (120); The first end of the flexible shaft (200) passes through the partition (121) from bottom to top, and the first end of the flexible shaft (200) is fixed in the inner cavity of the outer shaft (120).

4. The pulling shaft of a single crystal furnace according to claim 3, characterized in that, The flexible shaft (200) has first limiting portions (210) at both ends; connecting components (220) are respectively provided on both ends of the flexible shaft (200), and the flexible shaft (200) is connected to the rigid shaft (100) and the clamp assembly (300) respectively through two sets of connecting components (220), each set of connecting components (220) including: A sleeve (221) is used to connect with the inner shaft (110) or the clamp assembly (300). A channel (222) is provided on the side wall of the sleeve (221) and is arranged in a first direction and passes through the sleeve (221). The channel (222) can accommodate the flexible shaft (200) to enter the sleeve (221). The first limiting part (210) of the flexible shaft (200) abuts against the end of the sleeve (221) and is limited.

5. The pulling shaft of a single crystal furnace according to claim 3, characterized in that, The partition (121) has a recess (122) that is recessed into the inner cavity of the outer shaft (120); the top of the clamp assembly (300) has a protrusion (311) that corresponds to the recess (122), and the protrusion (311) moves up and down with the inner shaft (110) to form a first station and a second station with the recess (122): When the protrusion is in the first working position, the flexible shaft (200) extends outside the outer shaft (120), and the protrusion (311) and the recess (122) disengage from each other; When the protrusion is in the second working position, the flexible shaft (200) retracts into the interior of the outer shaft (120), and the protrusion (311) and the recess (122) abut against each other.

6. The pulling shaft of a single crystal furnace according to claim 5, characterized in that, The clamp assembly (300) includes: A counterweight (310) is connected to the flexible shaft (200); A clamp (320) is connected to the bottom of the counterweight (310) and is used to connect the seed crystal.

7. A pulling device for a single crystal furnace, used in a single crystal furnace, characterized in that, include: A lifting shaft, wherein the lifting shaft is the lifting shaft as described in any one of claims 2-6; A drive mechanism is connected to and acts on the lifting shaft to drive the lifting shaft to rotate and move up and down.

8. The pulling device for a single crystal furnace according to claim 7, characterized in that, The drive mechanism includes; The seat body includes: The first seat, the first seat is fixed; The second seat; the second seat is movably connected to the second seat, and the second seat has a vertical degree of freedom of movement; A first drive assembly, connected to the second seat and acting on the outer shaft (120), drives the outer shaft (120) to rotate, thereby causing the inner shaft (110) to rotate synchronously with the outer shaft (120); and The second driving component includes: The first driving component is connected to the first seat and acts on the outer shaft (120) to drive the lifting shaft to move up and down. The second driving member is connected to the second seat and acts on the inner shaft (110) to drive the inner shaft (110) to move up and down independently.

9. A single crystal furnace, characterized in that, include: Single crystal furnace body; The pulling device is the pulling device as described in any one of claims 7-8, and the pulling device is located at the top of the single crystal furnace body for vertically entering the single crystal furnace body to pull crystals.

10. A crystal pulling method using the Czochralski apparatus as described in any one of claims 7-8, characterized in that, include: The seed crystal on the fixture (320) is in contact with the surface of the liquid silicon; The lifting shaft is driven by the drive mechanism to rotate and lift the crystal rod upwards.

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