Liquid surface insulation device for crystal growth furnace and crystal growth furnace
By setting up a liquid level insulation device on the feeding port at the bottom of the water-cooled screen, the insulation body is used to slow down heat leakage, and the problem of uneven temperatures on the inner and outer sides of the silicon liquid in the crystal growth furnace is solved, and the crystal pulling speed and the consistency of the silicon core product is improved.
Patent Information
- Application Number
- CN202421541968.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-02
- Publication Date
- 2025-04-08
- Estimated Expiration
- 2034-07-02
AI Technical Summary
The temperatures of the inner and outer sides of the silicon liquid in the existing crystal growth furnaces are uneven, resulting in inconsistent crystal pulling speed and inconsistent diameter of the silicon core product, and the temperature in the center of the liquid surface is too low to crystallize.
A liquid level insulation device is designed, including a cover plate, a lifting joint, an insulating body and a ccd observation port. By setting the device on the feeding port at the bottom of the water-cooled screen, the insulating body is used to slow down heat leakage and ensure that the temperature difference between the inner and outer sides of the silicon liquid is small.
It effectively reduces the heat loss of silicon liquid, improves the crystal pulling speed, reduces the diameter difference of silicon core products, and avoids crystallization due to too low temperature in the center of the liquid level.
Smart Images
Figure CN222729951U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a furnace body insulation device, in particular to a liquid surface insulation device for a crystal growth furnace and the crystal growth furnace. Background Art
[0002] Monocrystalline silicon and polycrystalline silicon are important raw materials for industries such as semiconductors and photovoltaics. In the process of producing polycrystalline silicon / monocrystalline silicon, the amount of silicon cores used is very large. The most advanced silicon core preparation currently uses a multi-turn vertical pull crystal growth furnace to directly pull multiple silicon cores. The crystal growth furnace generally includes a furnace body, a crucible, a thermal field system, and a lifting mechanism. The principle is to heat the raw materials in the crucible through the thermal field system to melt it into a liquid state, and then use the lifting mechanism to send the seed crystal to the surface of the liquid silicon for seeding, so that the liquid raw material recrystallizes to form the required silicon core, and then the lifting mechanism rotates and slowly lifts it to gradually form a silicon crystal rod. In the process of recrystallization, in order to quickly cool the high-temperature liquid surface to the crystallization temperature, a water-cooled screen structure is required to control the temperature of the crystal growth position, thereby increasing the growth rate of the crystal.
[0003] At present, most of the common water-cooling screens in the industry adopt the mode of flat water-cooling screen, that is, a cooling plate is formed at the bottom of the water-cooling screen, a single crystal growth chamber is formed between the cooling plate and the crucible, a crystal rod retention chamber is formed on the upper side of the cooling plate, and an indefinite number of crystal pulling holes are distributed on the periphery of the cooling plate to facilitate the growth of the silicon core, and most of the central area is a feeding port that runs through from top to bottom. The crystal growth furnace insulates the silicon liquid in the entire crucible by setting an insulation layer on the periphery and bottom of the crucible. During the cooling and pulling process, the water-cooling screen is placed at a certain distance from the liquid surface in the center of the crucible, and the hollow area in the middle of the water-cooling screen is relatively large, resulting in a large amount of heat below the area being dissipated from the area to the crystal rod retention chamber. This heat is eventually taken away by the water-cooling screen, which easily causes the outer part of the silicon liquid to have a higher temperature and the central area to have a lower temperature, resulting in a large temperature difference between the inside and outside of the silicon liquid. At the same time, impurities may fall into the feeding port of the water-cooling screen, resulting in more oxides during the crystal pulling process, affecting the quality of the crystal rod.
[0004] Therefore, the existing crystal growth furnace has the problem of too fast heat loss above the silicon liquid, which will directly lead to a significant increase in energy consumption in the production process; and due to the uneven distribution of insulation, the temperature of the inner circle of the liquid surface will be lower than that of the outer circle during the crystal pulling process. The different temperatures of the silicon liquid will affect the crystal pulling speed. Therefore, the crystal pulling speed on the inside is inconsistent with the crystal pulling speed on the outside. At the same time, the inconsistent temperatures of the inner and outer circles will also cause the diameters of the silicon core products pulled by the inner and outer circles to be inconsistent. Since only the outer circle is insulated, it is easy to cause the temperature in the center of the liquid surface to be too low and crystallize during the temperature adjustment process. Summary of the invention
[0005] The utility model provides a liquid surface insulation device for a crystal growth furnace and a crystal growth furnace, which solve the problems of increased energy consumption and inconsistent silicon core products caused by excessively fast heat loss on the inner surface of silicon liquid in the crystal growth furnace in the prior art.
[0006] The above technical problems of the utility model are mainly solved by the following technical solutions: a liquid surface insulation device for a crystal growth furnace, the crystal growth furnace is a multi-turn vertical pull type crystal growth furnace, characterized in that it includes a cover plate, a hanging joint arranged on the upper surface of the cover plate, and a heat preservation body arranged on the lower surface of the cover plate, and the cover plate is also provided with a CCD observation port that simultaneously penetrates the heat preservation body. The cover plate in the utility model is used to fix and support the heat preservation body, and its material can be a high temperature resistant material such as metal and ceramic. The hanging joint is used to fix and dock with the lifting mechanism in the crystal growth furnace, so that the utility model can be sent to the feeding port at the bottom of the water cooling screen by controlling the lifting mechanism, and the entire feeding port is covered. The heat preservation body can isolate the heat at its bottom, slow down the rate of heat leakage, and ensure that the temperature difference between the inside and outside of the single crystal growth chamber is extremely small, thereby solving the directional problem caused by the uneven temperature inside and outside of the silicon liquid. The CCD observation port is for the camera to take visual photos facing the through hole, and the direction of the CCD observation port is facing the crystal pulling area.
[0007] Furthermore, the structure of the lifting joint matches the connection mode at the hanging point of the lifting mechanism in the existing crystal growth furnace, so that the entire insulation device can be lifted or placed by the lifting mechanism in the crystal growth furnace.
[0008] Furthermore, an annular supporting portion extending outwardly relative to the insulation body is provided at the edge of the cover plate. When the utility model is delivered to the bottom of the water-cooled screen, the outer diameter of the insulation body is generally slightly smaller than the size of the feeding port at the bottom of the water-cooled screen, so that the insulation body can be partially or completely embedded in the feeding port, and the annular supporting portion can abut against the bottom of the water-cooled screen to form upper and lower fixed limits. The utility model can be connected or separated with the water-cooled screen by direct plug-in and direct pull-out, and this action matches the action of the lifting mechanism, which is convenient for delivering the utility model to the bottom of the water-cooled screen or taking it out through the lifting mechanism.
[0009] Furthermore, the insulation body is a composite structure composed of a single layer or multiple layers of insulation materials of different thicknesses and materials. The ambient temperature at the bottom of the water-cooled screen is between 1400-1600°C, so the heat-resistant temperature of the insulation material is required to be at least 1600°C. Insulation materials that meet this condition include carbon-carbon composite materials, graphite, cured felt, soft felt, etc. Therefore, the insulation body can be composed of one or more of the above insulation materials and with different thicknesses.
[0010] The utility model also provides a crystal growth furnace, comprising a furnace body, a crucible arranged in the furnace body, a thermal field system arranged around the crucible, a water-cooling screen arranged above the crucible, and a lifting mechanism arranged on the upper side of the water-cooling screen, a cooling plate is formed at the bottom of the water-cooling screen, a single crystal growth chamber is formed between the cooling plate and the crucible, a crystal rod retention chamber is formed on the upper side of the cooling plate, a feeding port is formed in the middle of the cooling plate, and crystal pulling holes distributed around the feeding port are also provided on the cooling plate, characterized in that: a liquid surface insulation device can be hung and connected to the lifting mechanism, the liquid surface insulation device is the above-mentioned liquid surface insulation device, and the lifting mechanism can drive the liquid surface insulation device to descend until it abuts against the cooling plate and completely covers the feeding port.
[0011] Therefore, compared with the prior art, the utility model has the following characteristics: 1. By arranging a liquid surface insulation device on the feeding port at the bottom of the water-cooled screen, the heat dissipation in the central area of the silicon liquid in the crucible can be avoided from being too fast, thereby increasing the crystal pulling speed and reducing the diameter difference of the multi-turn silicon core products, while avoiding the temperature of the central area of the liquid surface being too low to cause crystallization, and by arranging a CCD observation port, the camera shooting angle required for normal process control is not affected; 2. The liquid surface insulation device is connected or separated from the cooling plate at the bottom of the water-cooled screen by direct plug-in and direct pull-out, and this action matches the action of the lifting mechanism in the existing crystal growth furnace, so that the utility model can be sent to the bottom of the water-cooled screen or taken out from it by the lifting mechanism; 3. The lifting joint on the liquid surface insulation device matches the connection method of the lifting mechanism in the existing crystal growth furnace, so that the hanging point of the lifting mechanism can realize automatic docking or automatic unloading with the lifting joint through its own forward and reverse rotation. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Attached Figure 1 It is a structural schematic diagram of a liquid surface insulation device;
[0013] Attached Figure 2 It is a partial structural schematic diagram of a crystal growth furnace, and the liquid surface insulation device is in a state of covering the feeding port;
[0014] Attached Figure 3 It is a partial structural schematic diagram of a crystal growth furnace, and the liquid surface insulation device is in a state of being lifted by a lifting mechanism. DETAILED DESCRIPTION
[0015] The technical solution of the utility model is further specifically described below through embodiments and in conjunction with the accompanying drawings.
[0016] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.
[0017] Example 1: See Figure 1 , a liquid surface insulation device for a crystal growth furnace, which is applicable to a multi-turn vertical pull crystal growth furnace, the insulation device comprises a cover plate 10, a hanging joint 20 arranged on the upper surface of the cover plate, and an insulation body 30 arranged on the lower surface of the cover plate, and a CCD observation port 40 which penetrates the insulation body at the same time is also provided on the cover plate; an annular supporting portion 50 extending outward relative to the insulation body is provided at the edge of the cover plate. The cover plate in this embodiment is used to fix and support the insulation body, and its material is a carbon-carbon composite material. The hanging joint is connected to the lifting mechanism through a detachable thread, and the material of the insulation body is a cured felt. The aperture of the CCD observation port is about 20-50mm.
[0018] See Figure 2 and Figure 3 This embodiment also discloses a crystal growth furnace, including a furnace body, a crucible 100 arranged in the furnace body, a thermal field system and a heat preservation component 200 arranged around the crucible, a water-cooled screen 300 arranged above the crucible, and a lifting mechanism arranged on the upper side of the water-cooled screen. A cooling plate 310 is formed at the bottom of the water-cooled screen, a single crystal growth chamber 400 is formed between the cooling plate and the crucible, a crystal rod retention chamber 500 is formed on the upper side of the cooling plate, a feeding port 311 is formed in the middle of the cooling plate, and a crystal pulling hole 312 distributed around the feeding port is also provided on the cooling plate. The lifting mechanism can be suspended and connected to the liquid surface heat preservation device 1, and the liquid surface heat preservation device is the above-mentioned liquid surface heat preservation device. The lifting mechanism can drive the liquid surface heat preservation device to descend to abut against the cooling plate and completely cover the feeding port. Since the furnace body, crucible, thermal field system, water-cooled screen, and lifting mechanism in this embodiment are all existing technologies, their corresponding specific structures and installation methods are not repeated here.
[0019] It is obvious to those skilled in the art that the utility model can be changed in many ways, and such changes are not considered to be out of the scope of the utility model. All such modifications obvious to those skilled in the art will be included in the scope of the claims.
Claims
1. A liquid surface insulation device for a crystal growth furnace, wherein the crystal growth furnace is a multi-turn vertical pull crystal growth furnace, characterized in that: It includes a cover plate, a hanging joint arranged on the upper surface of the cover plate, and a heat preservation body arranged on the lower surface of the cover plate. A CCD observation port which penetrates through the heat preservation body is also opened on the cover plate.
2. The liquid surface insulation device for a crystal growth furnace according to claim 1, characterized in that: An annular supporting portion extending outwardly relative to the heat-insulating body is provided at the edge of the cover plate.
3. The liquid surface insulation device for a crystal growth furnace according to claim 1 or 2, characterized in that: The heat-insulating body is a single-layer or multi-layer composite structure, and the heat-insulating body is made of heat-insulating material.
4. A crystal growth furnace, comprising a furnace body, a crucible arranged in the furnace body, a thermal field system arranged around the crucible, a water cooling screen arranged above the crucible, and a lifting mechanism arranged on the upper side of the water cooling screen, wherein a cooling plate is formed at the bottom of the water cooling screen, a feeding port is formed in the middle of the cooling plate, and crystal pulling holes distributed around the feeding port are also provided on the cooling plate, characterized in that: A liquid surface insulation device can be hung on the lifting mechanism, and the liquid surface insulation device is the liquid surface insulation device according to any one of claims 1 to 3. The lifting mechanism can drive the liquid surface insulation device to descend until it abuts against the cooling plate and completely covers the feeding port.