Seed crystal clamping device, seed crystal and material lifting method
By clamping seed crystals with melt silicon using seed crystal clamping device, directional solidification and growth are achieved, which solves the problem of melt silicon expansion and damage the thermal field after emergency shutdown during single crystal silicon growth, and reduces economic and environmental losses.
Patent Information
- Application Number
- CN202411853444.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-04-04
AI Technical Summary
During the growth of single crystal silicon, equipment failure leads to emergency shutdown, and the volume of the melt silicon expands after natural cooling, destroying the graphite thermal field, causing silicon material loss and environmental pollution.
A seed crystal clamping device is provided, including a seed crystal claw carrier disk, a plurality of seed crystal claws, a seed crystal latch and a seed crystal support disk, which is used to clamp the seed crystal and melt silicon to melt silicon, and to generate polycrystalline silicon through directional solidification and growth to avoid the natural solidification of melt silicon.
It effectively avoids graphite thermal field damage and silicon material loss caused by volume expansion after melt silicon naturally solidifies in the quartz crucible, reducing economic losses, safety hazards and environmental pollution.
Smart Images
Figure CN119753824A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor manufacturing, and in particular to a seed crystal clamping device, a seed crystal and a material extraction method. Background Art
[0002] The Czochralski method is the main method for growing semiconductor single crystal silicon. This method uses graphite resistance heating in a straight cylindrical furnace to melt the polycrystalline silicon in a high-purity quartz crucible, then inserts the seed crystal into the melt surface for welding, rotates the seed crystal at the same time, and then reverses the crucible. The seed crystal is slowly lifted upward, and after the processes of seeding, shoulder release, shoulder rotation, equal diameter growth, and finishing, it finally grows into a crystal rod of the required diameter and length.
[0003] With the development of semiconductor single crystal silicon growth technology and the increasing demand for large-size silicon wafers in the industry. The application of large-size thermal fields of 32 inches and above is becoming more and more extensive. The silicon material capacity in the quartz crucible reaches more than 400kg. Since the growth of single crystal silicon is in a high temperature, sealed, anaerobic environment above 1400 degrees Celsius, and the growth cycle is several days. In the crystal pulling process, although the frequency of occurrence is very low, it is inevitable that the equipment failure will cause the inability to continue crystal pulling and emergency shutdown. For example: when the silicon material is completely melted, the heater fails and cannot provide sufficient power output to meet the needs of crystal growth, and an emergency shutdown needs to be arranged. At this time, there is a large amount of molten silicon in the quartz crucible. Since the density of solid silicon is lower than that of molten silicon, the volume of molten silicon expands after natural cooling, and the quartz crucible, graphite crucible, graphite heater and other adjacent thermal field components are broken outward. In more serious cases, the molten silicon overflows into the heat field, causing damage to the heat field chassis, heaters, insulation materials and other heat field components or the furnace body, which brings great economic losses and safety hazards to normal production. At the same time, after being completely solidified, the silicon adheres to the quartz crucible or other graphite debris, which makes it extremely difficult to recycle the silicon material. It is often treated as solid waste, causing economic losses and environmental pollution.
[0004] Therefore, it is necessary to propose a device to solve the problems in the prior art. Summary of the invention
[0005] A series of simplified concepts are introduced in the Summary of the Invention section, which will be further described in detail in the Detailed Description of the Invention section. The Summary of the Invention section of this application does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.
[0006] In view of the existing problems, the present application provides a seed crystal clamping device, including:
[0007] A seed crystal clamping claw bearing plate, wherein a through hole is provided at the center of the seed crystal clamping claw bearing plate;
[0008] A plurality of seed crystal clamps, wherein the plurality of seed crystal clamps are spaced apart along the circumference of the seed crystal clamp bearing plate, each of the seed crystal clamps has a connecting end and a grabbing end, each of the connecting ends is movably connected to the seed crystal clamp bearing plate, and the grabbing end is used to grab the seed crystal;
[0009] A seed crystal plug, the seed crystal plug is inserted into the through hole;
[0010] A seed crystal support plate, the center of which is connected to one end of the seed crystal pin; a plurality of limit members are arranged on the seed crystal support plate, each of which is used to make the grasping end of one of the seed crystal clamps converge toward the axis of the seed crystal support plate when the seed crystal pin is pulled upward.
[0011] In some embodiments, the seed crystal clamp carrier plate and the seed crystal support plate are also connected via an elastic connector.
[0012] In some embodiments, the limiting member is an opening that passes through the seed crystal support plate, and each of the clamps is inserted into one of the openings. The distance between the opening and the center of the seed crystal support plate is smaller than the distance between the connecting end of the seed crystal clamp that limits it and the center of the seed crystal clamp carrying plate.
[0013] In some embodiments, the plurality of seed crystal jaws are evenly spaced apart along the circumference of the seed crystal jaw carrier.
[0014] A second aspect of an embodiment of the present application provides a seed crystal for generating polycrystalline silicon by directional solidification growth through a seed crystal clamping device as described in any one of the first aspects above, wherein the seed crystal is truncated cone-shaped, and the diameter of the upper bottom surface of the seed crystal is greater than the diameter of the lower bottom surface of the seed crystal.
[0015] In some embodiments, the diameters of the upper bottom surface of the seed crystal and the lower bottom surface of the seed crystal range from 100 mm to 500 mm.
[0016] In some embodiments, the thickness of the seed crystal ranges from 20 mm to 100 mm.
[0017] In some embodiments, the angle between the side generatrix of the seed crystal and the perpendicular line to the upper bottom surface of the seed crystal ranges from 3 degrees to 30 degrees, and the perpendicular line to the upper bottom surface of the seed crystal passes through an end point of the side generatrix.
[0018] A third aspect of the present application provides a material extraction method for use in an emergency shutdown process of single crystal silicon growth, comprising:
[0019] Loading the seed crystal as described in any one of the second aspects onto the seed crystal clamping device as described in any one of the first aspects, and mounting the seed crystal clamping device on the seed crystal chuck of the stopped furnace;
[0020] Lowering the seed crystal so that the seed crystal contacts the surface of the molten silicon in the quartz crucible;
[0021] The seed crystal is rotated and pulled so that the molten silicon is directionally solidified along the direction in which the seed crystal diffuses into the molten silicon to generate solid polycrystalline silicon.
[0022] In some embodiments, it also includes:
[0023] When the liquid level of the molten silicon drops to a safe position, the seed crystal is pulled up so that the solid polycrystalline silicon is separated from the remaining molten silicon, and thermal field cooling begins;
[0024] After the thermal field is cooled, the seed crystal chuck is lowered so that the seed crystal clamping device unloads the solid polysilicon into the quartz crucible and performs thermal field cleaning.
[0025] In some embodiments, rotating and pulling the seed crystal includes:
[0026] Rotating the seed crystal at a rotation speed of less than 10 revolutions per minute and rotating the quartz crucible at a rotation speed of less than 3 revolutions per minute;
[0027] The seed crystal is pulled at a speed of 0.5 mm / min to 5 mm / min.
[0028] The clamping device provided in the present application can clamp the seed crystal and fuse it with the molten silicon when an abnormal situation occurs after the silicon material is melted and triggers an emergency shutdown, and grow the molten silicon in the quartz crucible into polycrystalline silicon by directional solidification growth, thereby effectively avoiding the thermal field destruction of graphite and the loss of silicon material caused by the volume expansion of the molten silicon after natural solidification in the quartz crucible, thereby reducing economic losses, safety hazards and environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The following drawings of the present application are used as a part of the present application for understanding the present application. The drawings show the embodiments of the present application and their descriptions, which are used to explain the principle of the present application.
[0030] In the attached figure:
[0031] Figure 1 A schematic structural diagram of a seed crystal clamping device according to an embodiment of the present application is shown;
[0032] Figure 1a A top view of a seed crystal clamping claw supporting plate according to an embodiment of the present application is shown;
[0033] Figure 1b A bottom view of a seed crystal support plate according to an embodiment of the present application is shown;
[0034] Figure 2 A schematic diagram showing the structure of a seed crystal according to an embodiment of the present application is shown;
[0035] Figure 2a A schematic diagram showing the principle of loading a seed crystal by a seed crystal clamping device according to an embodiment of the present application is shown;
[0036] Figure 2b A schematic diagram showing the principle of unloading a seed crystal by a seed crystal clamping device according to an embodiment of the present application is shown;
[0037] Figure 3 A schematic flow chart of a material extraction method according to an embodiment of the present application is shown;
[0038] Figure 4 A schematic structural diagram of a crystal growth furnace according to an embodiment of the present application is shown. DETAILED DESCRIPTION
[0039] Next, the present application will be described more completely in conjunction with the accompanying drawings, in which embodiments of the present application are shown. However, the present application can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present application to those skilled in the art. In the accompanying drawings, for clarity, the sizes and relative sizes of layers and regions may be exaggerated. The same reference numerals throughout represent the same elements.
[0040] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as a second element, component, region, layer or part.
[0041] Spatially relative terms such as "under," "below," "below," "under," "above," "above," etc., may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.
[0042] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "a", "an", and "said / the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.
[0043] Embodiments of the invention are described herein with reference to cross-sectional views that are schematic diagrams of ideal embodiments (and intermediate structures) of the present application. Thus, variations from the shapes shown due to, for example, manufacturing techniques and / or tolerances can be expected. Therefore, embodiments of the present application should not be limited to the specific shapes of the zones shown herein, but include shape deviations due to, for example, manufacturing. For example, an implanted region shown as a rectangle typically has rounded or curved features and / or an implant concentration gradient at its edges, rather than a binary change from an implanted region to a non-implanted region. Similarly, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation is performed. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to show the actual shape of the region of the device and are not intended to limit the scope of the present application.
[0044] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by ordinary technicians in the field of this application. It will also be understood that terms such as those defined in commonly used dictionaries should be understood to have a meaning consistent with their meaning in the context of the relevant art and / or this specification, and should not be interpreted in an ideal or overly formal sense unless expressly defined as such herein.
[0045] At present, the preparation method of single crystal silicon ingot is mainly the direct pulling method. During the crystal pulling process, sometimes equipment failure occurs, resulting in the inability to continue crystal pulling and emergency furnace shutdown, which will cause damage to the thermal field components or the furnace body, and at the same time cause great difficulties in the recovery of silicon materials. Based on this, the present application provides a seed crystal clamping device, a seed crystal and a material extraction method, which can prevent the molten silicon from naturally solidifying in the quartz crucible, expanding in volume, destroying the graphite thermal field and causing silicon material loss, which are described in detail below.
[0046] In order to thoroughly understand the present application, detailed structures and / or steps will be presented in the following description to illustrate the technical solution proposed by the present application. The preferred embodiments of the present application are described in detail below, but in addition to these detailed descriptions, the present application may also have other implementation methods.
[0047] First refer to Figure 1 , the seed crystal clamping device of some embodiments of the present application is described in detail.
[0048] Figure 1 FIG. 1 shows a schematic structural diagram of a seed crystal clamping device according to an embodiment of the present application. Figure 1 As shown, the seed crystal clamping device 100 comprises: a seed crystal clamping claw bearing plate 110, a plurality of seed crystal clamping claws 120, a seed crystal pin 130 and a seed crystal supporting plate 140. The seed crystal clamping claw bearing plate 110 is arranged on the upper part of the seed crystal supporting plate 140. The seed crystal clamping claw bearing plate 110, the plurality of seed crystal clamping claws 120, the seed crystal pin 130 and the seed crystal supporting plate 140 can be made of high temperature resistant and corrosion resistant metal materials such as molybdenum. The seed crystal clamping device 100 is used to quickly clamp or unload the seed crystal.
[0049] A plurality of seed crystal jaws 120 are distributed at intervals along the circumference of the seed crystal jaw carrier plate 110 , and each seed crystal jaw 120 has a connecting end and a grabbing end, each connecting end is movably connected to the seed crystal jaw carrier plate 110 , and the grabbing end is used to grab the seed crystal.
[0050] Exemplarily, each connection end and the seed crystal clamp carrier plate 110 may be connected via a hinge. Of course, each connection end and the seed crystal clamp carrier plate 110 may also be movably connected via other means, and the present application does not specifically limit the manner of the movably connected means.
[0051] The center of the seed crystal support plate 140 is connected to one end of the seed crystal pin 130; a plurality of limit members (not shown in the figure) are arranged on the seed crystal support plate 140, and each limit member is used to make the grasping end of a seed crystal clamp 120 converge toward the axis of the seed crystal support plate 140 when the seed crystal pin 130 is pulled upward, thereby achieving the grasping of the seed crystal.
[0052] In the present application, the limiter on the seed crystal support plate 140 is arranged correspondingly to the seed crystal clamping claws, and the number is the same. The seed crystal plug 130 is used to connect with the seed crystal clamping head in the crystal growth furnace.
[0053] Preferably, the seed crystal pin 130 may be integrated with the seed crystal supporting plate 140 , thereby simplifying the structure of the seed crystal clamping device 100 .
[0054] Figure 1a FIG. 4 shows a top view of a seed crystal clamping claw supporting plate according to an embodiment of the present application. Figure 1a As shown, a through hole 111 is provided at the center of the seed crystal clamping claw supporting plate 110 , and the seed crystal plug 130 can be inserted into the through hole 111 .
[0055] The clamping device provided in the present application can clamp the seed crystal and fuse it with the molten silicon when an abnormal situation occurs after the silicon material is melted and triggers an emergency shutdown, and grow the molten silicon in the quartz crucible into polycrystalline silicon by directional solidification growth, thereby effectively avoiding the thermal field destruction of graphite and the loss of silicon material caused by the volume expansion of the molten silicon after natural solidification in the quartz crucible, thereby reducing economic losses, safety hazards and environmental pollution.
[0056] Please continue reading Figure 1 In some embodiments, the seed crystal clamp carrier plate 110 and the seed crystal support plate 140 are further connected via an elastic connector 150 .
[0057] Specifically, the elastic connecting member 150 may be a spring.
[0058] By providing the elastic connector 150, after the crystal pulling is completed and the polysilicon is lowered into the crucible, the force of the crystal acting on the elastic connector 150 is reduced, driving the seed crystal clamp carrier plate 110 to move upward, and the grabbing end of the seed crystal clamp 120 opens, so that the polysilicon can be separated from the clamping device.
[0059] In some embodiments, the number of seed crystal clamps ranges from 3 to 6. Specifically, the plurality of seed crystal clamps are evenly spaced and distributed along the circumference of the seed crystal clamp carrier plate.
[0060] Please continue reading Figure 1 , Figure 1 The number of the seed crystal clamps 120 is 4, and the plurality of seed crystal clamps 120 are evenly spaced along the circumference of the seed crystal clamp carrier plate 110 , and the distance between two adjacent seed crystal clamps 120 is one quarter of the circumference.
[0061] In some embodiments, the limiting member is an opening passing through the seed crystal support plate, each clamp is inserted into an opening, and the distance between the opening and the center of the seed crystal support plate is smaller than the distance between the connecting end of the seed crystal clamp that limits it and the center of the seed crystal clamp supporting plate.
[0062] Figure 1b FIG. 4 shows a bottom view of a seed crystal support plate according to an embodiment of the present application. Figure 1bAs shown, the seed crystal supporting plate 140 has four openings, namely a first opening 141 , a second opening 142 , a third opening 143 and a fourth opening 144 . The four openings are evenly distributed along the circumference of the seed crystal supporting plate 140 .
[0063] Since the distance from the opening to the center of the seed crystal support plate is smaller than the distance between the connecting end of the jaw and the center of the seed crystal jaw carrying plate, the closer the distance between the seed crystal jaw carrying plate and the seed crystal support plate is, the more the jaws are closed, and the farther the distance is, the more the jaws are open; thus, when the seed crystal support plate is driven upward by the seed crystal pin to pull the seed crystal, the seed crystal jaw carrying plate moves downward and approaches the seed crystal support plate due to the gravity of the seed crystal, and the jaws are closed to clamp the seed crystal.
[0064] The present application also provides a seed crystal for generating polycrystalline silicon in a directional solidification growth manner through the above-mentioned seed crystal clamping device.
[0065] Next, see Figure 2 A seed crystal according to an embodiment of the present application is described below.
[0066] like Figure 2 As shown, the seed crystal 200 is in a truncated cone shape, and the diameter of the upper bottom surface of the seed crystal is larger than the diameter of the lower bottom surface of the seed crystal. The seed crystal material is single crystal silicon, carbon-carbon composite material, etc.
[0067] The frustum-shaped seed crystal enables the seed crystal clamping device to be loaded and unloaded automatically, making the operation easier.
[0068] In some embodiments, the diameters of the upper bottom surface of the seed crystal and the lower bottom surface of the seed crystal range from 100 mm to 500 mm.
[0069] In some embodiments, the thickness of the seed crystal ranges from 20 mm to 100 mm.
[0070] The embodiment of the present application adopts large-sized seed crystals with diameters ranging from 100 mm to 500 mm, which can effectively reduce the time required for traditional small-sized seed crystals (such as seed crystals with diameters of 12.5 mm or 17.5 mm) to expand the size of crystalline silicon through the shoulder release process, thereby shortening the processing time and improving safety during the handling of emergency events.
[0071] Please continue reading Figure 2 In some embodiments, the angle between the side generatrix AB of the seed crystal and the perpendicular line BC of the upper bottom surface of the seed crystal ranges from 3 degrees to 30 degrees, and the perpendicular line BC of the upper bottom surface of the seed crystal passes through the end point B of the side generatrix AB. Since the seed crystal is truncated cone-shaped, the side generatrix of the seed crystal is the side generatrix of the truncated cone.
[0072] When the angle formed by the side generatrix of the seed crystal and the perpendicular line of the upper bottom surface of the seed crystal is in the range of 3 degrees to 30 degrees, the seed crystal clamping device can conveniently clamp and unload the seed crystal.
[0073] Next, see Figure 2a and Figure 2b The process of loading and unloading a seed crystal on a seed crystal holding device according to an embodiment of the present application is described.
[0074] like Figure 2a As shown, when multiple seed crystal clamps 120 clamp the seed crystal 200, the seed crystal pin 130 and the seed crystal support plate 140 are pulled upward together, and the seed crystal clamp bearing plate 110 is moved downward to approach the seed crystal support plate 140 under the action of external force, and at the same time, the elastic connector 150 contracts due to the downward pressure of the seed crystal clamp bearing plate 110, and the clamps 120 are closed to clamp the seed crystal 200. After the folding, the gravity of the seed crystal 200 is borne by the seed crystal support plate 140, and transmitted to the seed crystal clamp bearing plate 110, and the position of the seed crystal clamp 120 is locked. After the external force is released, the seed crystal 200 is stably locked in the seed crystal clamping device.
[0075] like Figure 2b As shown, after the crystal growth is completed, the seed crystal pin 130 and the seed crystal support plate 140 descend together to lower the polycrystalline silicon into the crucible. When the polycrystalline silicon is lowered into the crucible, the interaction force between the seed crystal 200 and the seed crystal clamp 120 disappears, and the elastic connecting member 150 pushes the seed crystal clamp supporting plate 110 to move upward, and the grabbing end of the seed crystal clamp 120 opens, so that the seed crystal 200 can be separated from the clamping device.
[0076] The present application also provides a material extraction method for use in an emergency shutdown process for single crystal silicon growth.
[0077] Next, see Figure 3 To illustrate a material extraction method according to an embodiment of the present application.
[0078] like Figure 3 As shown, the material extraction method includes the following steps S310-S330.
[0079] In step S310, the seed crystal is loaded onto the seed crystal clamping device in any of the above embodiments, and the seed crystal clamping device is mounted on the seed crystal chuck of the stopped furnace. Specifically, the seed crystal in this embodiment is a large-size seed crystal with a diameter ranging from 100 mm to 500 mm.
[0080] Since single crystal silicon grows in a sealed, anaerobic environment at a temperature of over 1400 degrees Celsius, and the growth cycle is several days, during the crystal pulling process, although the frequency of occurrence is very low, it is inevitable that equipment failure will cause the inability to continue crystal pulling and emergency shutdown. For example, when the silicon material is completely melted, the heater fails and cannot provide sufficient power output to meet the needs of crystal growth. At this time, an emergency shutdown needs to be arranged.
[0081] When an emergency shutdown is triggered due to equipment failure, the seed crystal of the present application is quickly loaded onto the original seed crystal clamping device and mounted on the original seed crystal chuck through the seed crystal latch.
[0082] In step S320 , the seed crystal is lowered so as to contact the surface of the molten silicon in the quartz crucible.
[0083] In the process of slowly descending to the surface of molten silicon, the preheating of the large-sized seed crystal is completed. Usually, the thermal field has good thermal insulation performance. When the heater stops or works at low power, the heat capacity of the thermal field system can keep the molten silicon in a liquid state without solidifying for a certain period of time. When the large-sized seed crystal contacts the molten silicon, since the large-sized solid seed crystal has a larger radiation heat dissipation coefficient than the surface of the molten silicon, its heat dissipation capacity is stronger. Once in contact with the molten silicon, a temperature gradient structure can be quickly formed from the large-sized seed crystal as the cold end to the inside of the thermal field as the hot end, thereby directional solidification along the bottom section of the large-sized seed crystal toward the inside of the molten silicon.
[0084] In step S330, the seed crystal is rotated and pulled so that the molten silicon is directionally solidified along the direction in which the seed crystal diffuses into the molten silicon to generate solid polycrystalline silicon.
[0085] When an abnormal situation occurs, the molten silicon changes from a natural cooling solidification mode to a directional solidification mode in which the seed crystal diffuses into the melt along the seed crystal in the present application.
[0086] Due to the elevation of the seed crystal position, the solid silicon is orderly lifted upward in the quartz crucible, which can effectively avoid the damage of thermal field components such as the graphite crucible and heater caused by the free solidification and volume expansion of the molten silicon from the surface to the inside of the quartz crucible. At the same time, as the liquid level drops, the solid silicon directionally solidified on the large-sized seed crystal is not contaminated by quartz debris, which is convenient for the secondary recycling of silicon raw materials.
[0087] In some embodiments, the extraction method further comprises:
[0088] When the liquid level of the molten silicon drops to a safe position, the seed crystal is pulled up to separate the solid polysilicon from the remaining molten silicon, and thermal field cooling begins;
[0089] After the hot field is cooled, the seed crystal chuck is lowered so that the seed crystal clamping device unloads the solid polysilicon into the quartz crucible and performs hot field cleaning.
[0090] As the solidification process proceeds, the melt level drops. When the liquid level drops below a safe position, such as below the R angle of the quartz crucible, the solid silicon is quickly lifted out of contact with the liquid surface. After the solid silicon is separated from the bottom molten silicon, it stops moving and begins thermal field cooling.
[0091] After the heat field is cooled, the seed crystal chuck is lowered, and the solid silicon growing along the seed crystal falls on the surface of the free crystallized solid silicon in the quartz crucible. The seed crystal claw is relaxed by the spring and automatically breaks away from the contact with the seed crystal. After the seed crystal chuck of the single crystal furnace rises freely, the subsequent heat field cleaning work can be carried out. The solid silicon can be taken out together with the quartz crucible for separation and recovery.
[0092] In some embodiments, rotating and pulling the seed crystal includes:
[0093] The seed crystal is rotated at a rotation speed of less than 10 revolutions per minute while the quartz crucible is rotated at a rotation speed of less than 3 revolutions per minute; and the seed crystal is pulled at a speed of 0.5 mm / min to 5 mm / min.
[0094] In this embodiment, during the directional solidification process, the seed crystal rotates at a certain speed and is slowly lifted, and the pulling speed is lower than the conventional single crystal silicon pulling speed. The above rotation speed and pulling speed can make the size of the solidified part smaller than the inner diameter of the quartz crucible.
[0095] Next, see Figure 4 To illustrate the material extraction method according to another embodiment of the present application.
[0096] Figure 4 A schematic diagram of a crystal growth furnace used in the material extraction method provided in an embodiment of the present application is shown. The crystal growth furnace is used to grow silicon single crystals using the Czochralski method and to implement the material extraction method of this embodiment during emergency shutdown.
[0097] like Figure 4 As shown, the furnace body of the crystal growth furnace includes: a furnace shell 401, in which a heating device and a pulling device are arranged. The heating device includes a quartz crucible 402, a graphite crucible 403, and a heater 404. Among them, the quartz crucible 402 is used to hold silicon materials, such as polycrystalline silicon. The silicon materials are heated into molten silicon 405 therein. The graphite crucible 403 is wrapped around the outside of the quartz crucible 402, and is used to provide support for the quartz crucible 402 during the heating process. The heater 404 is arranged on the outside of the graphite crucible 403. A heat shield is arranged above the quartz crucible 402, and the heat shield includes a guide tube 406, which is connected to the furnace shell 401 through a guide tube support rod 407. The guide tube 406 has an inverted cone-shaped screen-shaped object extending downward and surrounding the silicon single crystal growth area, which can block the direct heat radiation of the heater 404 and the high-temperature molten silicon 405 to the growing single crystal silicon ingot, thereby reducing the temperature of the single crystal silicon ingot. At the same time, the heat shield can also concentrate the downwardly blown protective gas and spray it directly near the growth interface, further enhancing the heat dissipation of the single crystal silicon ingot. A graphite cover plate 408 is arranged around the guide tube 406. A graphite support tube 409 is also arranged on the side wall of the furnace shell 401.
[0098] The seed crystal lifting device includes a seed crystal rope 411 and a seed crystal chuck 412 which are vertically arranged in the sub-chamber 410 of the single crystal furnace. The seed crystal rope 411 and the seed crystal chuck 412 are arranged above the quartz crucible 402. The seed crystal chuck 412 is installed with a seed crystal and a seed crystal clamping device 100. The top of the seed crystal rope is connected to a seed crystal rope driving device 413 so that it can be slowly pulled upward while rotating.
[0099] In one specific implementation, the quartz crucible 402 is 32 inches.
[0100] When growing a single crystal, firstly, 500 kg of silicon material is put into the quartz crucible 402 , and then the heater 404 is turned on to heat and melt the silicon material into molten silicon 405 .
[0101] When the melting is completed, the power module of the heater 404 fails, and the power of the heater 404 cannot be controlled to change according to the process setting curve. Subsequent processes such as seeding, shoulder release, equal diameter growth, and finishing cannot be completed.
[0102] If the cooling process is started, the molten silicon 405 in the crucible will cool naturally and expand in volume, which will inevitably break the graphite crucible 402, heater 404, insulation barrel and other major thermal field components. To avoid the above additional losses, the method of this embodiment is used for processing.
[0103] A 300mm frustum-shaped monocrystalline silicon is used as a large-size seed crystal. The seed crystal thickness is 50mm, and the angle between the side busbar and the vertical line of the seed crystal upper bottom surface is 15 degrees. Figure 4The seed crystal clamping device 100 is shown, and is mounted on the seed crystal chuck 412 in the single crystal furnace through the seed crystal pin. The single crystal furnace sub-chamber 410 is closed, and the pressure of the single crystal furnace sub-chamber 410 and the main furnace chamber is balanced. The seed crystal chuck 412 drives the large-sized seed crystal and the seed crystal clamping device 100 to descend at a speed of 20mm / min to a distance of about 300mm from the lower surface of the large-sized seed crystal to the liquid surface of the molten silicon 405; then the speed is changed to 10mm / min, and the lower surface of the large-sized seed crystal is lowered to a distance of about 100mm from the liquid surface of the molten silicon 405; then the speed is changed to 5mm / min, and the lower surface of the large-sized seed crystal is lowered to a position of about 30mm from the liquid surface of the molten silicon 405; then the speed is changed to 1mm / min, and the large-sized seed crystal is slowly lowered and penetrates about 10mm below the liquid surface of the molten silicon 405. The seed crystal rotates at 5RPM, the power of the heater 404 is reduced, and the molten silicon 405 begins to grow around the large-sized seed crystal (directional solidification), and the seed crystal pulling speed is set to 1mm / min. As the growth process proceeds, the size of the solid silicon 201 gradually grows, and the liquid level of the molten silicon 405 drops rapidly. When the liquid level of the molten silicon 405 drops below the R angle of the quartz crucible 402, the heater 404 is completely turned off, and the seed crystal pulling speed is increased to 3mm / min until it is completely out of contact with the molten silicon 405, and the seed crystal pulling speed is set to 0. After the machine is completely cooled, the seed crystal rope 411 is lowered, and after the solid silicon 201 grown along the large-sized seed crystal falls into the quartz crucible 402, the large-sized seed crystal clamp loses its support force on the truncated cone seed crystal, and the two are naturally separated. The seed crystal chuck 412 is raised to the single crystal furnace sub-chamber 410, and the single crystal furnace is opened for hot field cleaning and equipment maintenance.
[0104] Using the large-size seed crystal device and process of this embodiment, about 300 kg of solid silicon grown on the large-size seed crystal was taken out with the quartz crucible 402. The thermal field components such as the graphite crucible 403 and the heater 404 were intact and not damaged due to equipment failure.
[0105] In another embodiment, after the melting is completed, the power module of the heater 404 fails, and the power is sharply reduced to 10% of the set power, making it impossible to continue to complete the subsequent processes such as seeding, shoulder release, equal diameter growth, and finishing.
[0106] If the cooling process is started, the molten silicon in the quartz crucible 402 cools naturally and expands in volume, which will inevitably break the graphite crucible 403, heater 404, insulation barrel and other major thermal field components. To avoid the above additional losses, the material extraction method of this embodiment is used for emergency treatment.
[0107] Considering that the power of heater 404 is very low and the temperature of the thermal field is dropping rapidly, it is necessary to complete the welding of the seed crystal and the molten silicon 405 as quickly as possible. Therefore, a 300mm truncated cone carbon-carbon material is used as a large-sized seed crystal to avoid cracking and breaking of the seed crystal due to the rapid rise in temperature during the descent of the seed crystal. Similarly, the thickness of the large-sized seed crystal is 40mm, and the angle between the side busbar and the vertical line of the upper bottom surface of the seed crystal is 15 degrees. Load the seed crystal into Figure 4 The seed crystal clamping device 100 is shown, and is mounted on the seed crystal chuck 412 in the single crystal furnace through the seed crystal pin. The single crystal furnace sub-chamber 410 is closed, and the pressure of the main furnace chamber of the single crystal furnace sub-chamber 410 is balanced. The seed crystal chuck 412 drives the large-sized seed crystal and the seed crystal clamping device 100 to quickly descend at a speed of 200mm / min to the lower surface of the large-sized seed crystal to the liquid surface of the molten silicon 405, which is about 10mm away; then the speed is changed to 3mm / min, and the large-sized seed crystal is slowly lowered and intruded about 10mm below the liquid surface of the molten silicon 405. The seed crystal rotates at a speed of 5RPM, and the graphite crucible 402 rotates at 0RPM.
[0108] Due to the drop in the temperature of the thermal field, the temperature of the molten silicon 405 drops, and crystal flakes have floated out of the surface. As soon as the large-sized seed crystal contacts the melt, it begins to grow rapidly around the large-sized seed crystal (directional solidification). The seed crystal pulling speed is set to 2mm / min, and the seed crystal rotation is turned off. As the growth process proceeds, the size of the solid silicon 201 gradually grows, and the liquid level of the molten silicon 405 drops rapidly. Since a large amount of latent heat of crystallization is released during solidification, the free solidification process of the molten silicon 405 is delayed.
[0109] When the liquid level of molten silicon 405 drops below the R angle of quartz crucible 402, completely turn off heater 404, and increase the seed crystal pulling speed to 5mm / min. After quickly breaking away from molten silicon 405, set the seed crystal pulling speed to 0. After the machine is completely cooled, lower the seed crystal rope 411. After the solid silicon 201 grown along the large-sized seed crystal falls into the quartz crucible 402, the large-sized seed crystal clamp loses its support force on the truncated cone seed crystal, and the two naturally separate. Raise the seed crystal chuck 412 to the single crystal furnace sub-chamber 410, open the single crystal furnace for hot field cleaning and equipment maintenance.
[0110] By applying the seed crystal clamping device of this embodiment and the material extraction process based on the large-sized seed crystal, about 200 kg of solid silicon grown on the large-sized seed crystal was taken out with the quartz crucible. The thermal field components such as the graphite crucible 403 and the heater 404 were intact and were not damaged due to equipment failure.
[0111] Although multiple embodiments are described herein, it should be understood that a variety of other modifications and embodiments may be conceived by those skilled in the art, all of which will fall within the spirit and scope of the concepts disclosed herein. More particularly, various modifications and changes may be made to the arrangements and / or components of the combined arrangements of the subject matter within the scope of the disclosure, drawings, and appended claims of the present application. In addition to modifications and changes to the components and / or arrangements, the use of alternatives is also an obvious option for those skilled in the art.
Claims
1. A seed crystal clamping device, characterized in that: include: A seed crystal clamping claw bearing plate, wherein a through hole is provided at the center of the seed crystal clamping claw bearing plate; A plurality of seed crystal clamps, wherein the plurality of seed crystal clamps are spaced apart along the circumference of the seed crystal clamp bearing plate, each of the seed crystal clamps has a connecting end and a grabbing end, each of the connecting ends is movably connected to the seed crystal clamp bearing plate, and the grabbing end is used to grab the seed crystal; A seed crystal plug, the seed crystal plug is inserted into the through hole; A seed crystal support plate, the center of which is connected to one end of the seed crystal pin; a plurality of limit members are arranged on the seed crystal support plate, each of which is used to make the grasping end of one of the seed crystal clamps converge toward the axis of the seed crystal support plate when the seed crystal pin is pulled upward.
2. The seed crystal clamping device according to claim 1, characterized in that: The seed crystal clamping claw bearing plate and the seed crystal supporting plate are also connected via an elastic connecting piece.
3. The seed crystal clamping device according to any one of claims 1 to 2, characterized in that: The limiting member is an opening that passes through the seed crystal support plate, and each of the clamps is inserted into one of the openings. The distance between the opening and the center of the seed crystal support plate is smaller than the distance between the connecting end of the seed crystal clamp that limits it and the center of the seed crystal clamp bearing plate.
4. The seed crystal clamping device according to any one of claims 1 to 2, characterized in that: The plurality of seed crystal clamps are evenly spaced and distributed along the circumference of the seed crystal clamp bearing plate.
5. A seed crystal, characterized in that: Used to generate polycrystalline silicon by directional solidification growth using a seed crystal clamping device according to any one of claims 1 to 4, characterized in that the seed crystal is truncated cone-shaped, and the diameter of the upper bottom surface of the seed crystal is greater than the diameter of the lower bottom surface of the seed crystal.
6. The seed crystal according to claim 5, characterized in that: The diameters of the upper bottom surface of the seed crystal and the lower bottom surface of the seed crystal range from 100 mm to 500 mm.
7. The seed crystal according to claim 5, characterized in that: The thickness of the seed crystal ranges from 20 mm to 100 mm.
8. The seed crystal according to claim 5, characterized in that: The angle formed by the side generatrix of the seed crystal and the perpendicular line to the upper bottom surface of the seed crystal ranges from 3 degrees to 30 degrees, and the perpendicular line to the upper bottom surface of the seed crystal passes through an end point of the side generatrix.
9. A material extraction method, characterized in that: Used in the emergency shutdown process of single crystal silicon growth, including: Loading the seed crystal according to any one of claims 5 to 8 onto the seed crystal holding device according to any one of claims 1 to 4, and mounting the seed crystal holding device on the seed crystal chuck of the stopped furnace; Lowering the seed crystal so that the seed crystal contacts the surface of the molten silicon in the quartz crucible; The seed crystal is rotated and pulled so that the molten silicon is directionally solidified along the direction in which the seed crystal diffuses into the molten silicon to generate solid polycrystalline silicon.
10. The material extraction method according to claim 9, characterized in that: Also includes: When the liquid level of the molten silicon drops to a safe position, the seed crystal is pulled up so that the solid polycrystalline silicon is separated from the remaining molten silicon, and thermal field cooling begins; After the thermal field is cooled, the seed crystal chuck is lowered so that the seed crystal clamping device unloads the solid polysilicon into the quartz crucible and performs thermal field cleaning.
11. The material extraction method according to claim 9, characterized in that: The rotating and pulling the seed crystal comprises: Rotating the seed crystal at a rotation speed of less than 10 revolutions per minute and rotating the quartz crucible at a rotation speed of less than 3 revolutions per minute; The seed crystal is pulled at a speed of 0.5 mm / min to 5 mm / min.