Heat shield of single crystal furnace

Abstract

The utility model relates to a heat shield of a single crystal furnace, the heat shield comprises a lower heat shield and an upper heat shield arranged on the lower heat shield, the lower heat shield comprises a lower outer cylinder and a lower inner cylinder arranged in the lower outer cylinder, and a first thermal insulation layer is arranged between the lower outer cylinder and the lower inner cylinder; an annular supporting part is arranged at the upper end of the lower outer cylinder, a plurality of hoisting plates are evenly distributed at the upper end of the annular supporting part, and hoisting holes are formed in the hoisting plates; the upper heat shield comprises an upper outer cylinder and an upper inner cylinder arranged in the upper outer cylinder, a second heat preservation layer is arranged between the upper outer cylinder and the upper inner cylinder, an annular bottom is arranged at the lower end of the upper outer cylinder, the upper inner cylinder is located at the upper end of the annular bottom, and the annular supporting part extends into the upper inner cylinder and abuts against the inner wall of the upper inner cylinder. The annular bottom abuts against the outer wall of the lower outer cylinder. The split type structure is adopted, the upper heat shield is located at the upper end of the lower heat shield, and the hoisting plate is arranged on the lower heat shield, so that the lifting space is increased during hoisting, and the feeding amount is increased.

Description

Technical Field

[0001] The utility model relates to the technical field of Czochralski single crystal technology, and particularly relates to a thermal shield of a single crystal furnace. Background Technique

[0002] The single crystal pulling thermal shield has multiple functions in the single crystal growth process, such as stabilizing the temperature of the melting zone, controlling the crystal growth rate, improving the crystal quality, optimizing the gas flow field, increasing the crystal pulling rate, and reducing stress. These functions jointly promote the smooth progress of the single crystal growth process and the improvement of crystal quality.

[0003] However, with the further reduction of production costs and the high oxygen content requirements of some customers' products, there is a further requirement for increasing the initial charge amount from the source. This requires avoiding the interference between the polycrystalline material and the thermal shield during loading. In the limited space of the single crystal furnace, enough space needs to be reserved for loading. Most of the existing thermal shields are integral, and the lifting part is located at the upper end of the thermal shield. The reserved space for lifting the integral thermal shield depends on the distance between the upper edge of the thermal shield and the inner wall of the furnace cover. The existing integral thermal shield has the lifting part located at the upper edge of the thermal shield, resulting in limited lifting space, so the charge amount is small. As the charge amount increases, in order to avoid the risk of silicon leakage during the melting process, high crucible position melting is required. It is reported that the lifting space of the integral lifting thermal shield is limited, resulting in limited rise of the crucible position during melting, and the melting crucible position is still relatively low, and there are still phenomena such as hanging on the edge, bridging, and even silicon leakage during the melting process; moreover, all the graphite parts of the integral thermal shield are obtained by isostatic pressing purification and then machining. The larger the size, the higher the procurement cost, and at the same time, the larger the size, the greater the internal stress. Content of the Utility Model

[0004] In view of the problems existing in the prior art, the utility model provides a thermal shield of a single crystal furnace.

[0005] The technical solution adopted by the utility model to solve the above technical problems is: a thermal shield of a single crystal furnace, including a lower thermal shield and an upper thermal shield arranged on the lower thermal shield. The lower thermal shield includes a lower outer cylinder and a lower inner cylinder arranged inside the lower outer cylinder. A first heat insulation layer is arranged between the lower outer cylinder and the lower inner cylinder; an annular support part extending outward is arranged at the upper end of the lower outer cylinder. A plurality of lifting plates are evenly distributed along the circumferential direction at the upper end of the annular support part, and lifting holes for lifting are arranged on the lifting plates;

[0006] The upper thermal shield includes an upper outer cylinder and an upper inner cylinder arranged inside the upper outer cylinder. A second heat insulation layer is arranged between the upper outer cylinder and the upper inner cylinder. An annular bottom extending outward is arranged at the lower end of the upper outer cylinder. The upper inner cylinder is located at the upper end of the annular bottom. The annular support part passes through the annular bottom and extends into the upper inner cylinder and abuts against the inner wall of the upper inner cylinder, and the annular bottom abuts against the outer wall of the lower outer cylinder.

[0007] As a preferred solution, the upper end of the outer upper cylinder is provided with a first annular portion extending outward, and the upper end of the inner upper cylinder is provided with a second annular portion extending outward. The second annular portion is located above the first annular portion.

[0008] As a preferred solution, the inner upper cylinder includes a first tapered cylinder and a second tapered cylinder arranged in sequence from bottom to top along its axis.

[0009] As a preferred solution, the large end of the first tapered cylinder faces upward and is connected to the small end of the second tapered cylinder.

[0010] As a preferred solution, the taper of the first tapered cylinder is smaller than that of the second tapered cylinder.

[0011] As a preferred solution, both the first thermal insulation layer and the second thermal insulation layer are soft felts.

[0012] The beneficial effects of the present application are as follows: 1. The present application adopts a split structure. The upper thermal shield is located above the lower thermal shield, and the lifting plate is arranged on the lower thermal shield, which increases the lifting space during hoisting. Compared with the existing integrated thermal shield, the feeding amount is greatly increased. At the same time, due to the increased lifting space during hoisting,

[0013] it is possible to carry out high-pot crucible melting during the melting process, thereby avoiding problems such as hanging on the edge and bridging during the melting process.

[0014] 2. The present application adopts a split structure, which can reduce the procurement cost and at the same time reduce the stress of the graphite material, and the production cost is lower.

[0015] 3. By setting the first thermal insulation layer and the second thermal insulation layer, the thermal insulation effect is increased. The materials of the first thermal insulation layer and the second thermal insulation layer are both soft felts, which have a small thermal conductivity and good heat insulation performance, so that the temperature of the inner layer is not easily transmitted to the outer layer, thereby improving the thermal insulation performance of the thermal shield and ensuring the normal production of single crystal silicon. Description of the Drawings

[0016] Figure 1 is a schematic structural diagram of the present invention;

[0017] Figure 2 is a front view of the present invention;

[0018] Figure 3 is a sectional view of the present invention.

[0019] Markings in the figure: 1. Lower thermal shield, 11. Outer lower cylinder, 111. Annular support portion, 12. Inner lower cylinder, 13. First thermal insulation layer, 2. Upper thermal shield, 21. Outer upper cylinder, 211. Annular bottom, 212. First annular portion, 22. Inner upper cylinder, 221. Second annular portion, 222. First tapered cylinder, 223. Second tapered cylinder, 23. Second thermal insulation layer, 3. Lifting plate. Detailed implementation mode

[0020] In order to make the purpose, technical solution and advantages of the present utility model clearer, the present utility model will be further described in detail below with reference to the drawings and embodiments. It should be understood that in the description of the present utility model, unless otherwise specified, the meaning of "a plurality" is two or more; the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present utility model. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0021] Please refer to Figure 1 , an embodiment of the present utility model provides a thermal shield for a single crystal furnace, which includes a lower thermal shield 1 and an upper thermal shield 2 arranged on the lower thermal shield 1. The lower thermal shield 1 includes a lower outer cylinder 11 and a lower inner cylinder 12 arranged inside the lower outer cylinder 11. A first heat insulation layer 13 is provided between the lower outer cylinder 11 and the lower inner cylinder 12; an annular support portion 111 extending outward is provided at the upper end of the lower outer cylinder 11; the upper thermal shield 2 includes an upper outer cylinder 21 and an upper inner cylinder 22 arranged inside the upper outer cylinder 21. A second heat insulation layer 23 is provided between the upper outer cylinder 21 and the upper inner cylinder 22. An annular bottom portion 211 extending outward is provided at the lower end of the upper outer cylinder 21. The upper inner cylinder 22 is located above the annular bottom portion 211. The annular support portion 111 passes through the annular bottom portion 211 and extends into the upper inner cylinder 22 and abuts against the inner wall of the upper inner cylinder 22, and the annular bottom portion 211 abuts against the outer wall of the lower outer cylinder 11.

[0022] Wherein, the annular bottom portion 211 is conical with the large end facing up and the small end facing down. When the lower thermal shield 1 descends, it can slide down to the lower edge of the upper thermal shield 2 under the action of its own gravity while maintaining the vertical concentricity. The lower edge of the upper thermal shield is the annular bottom portion 211.

[0023] Both the upper and lower ends of the lower outer cylinder 11 and the lower inner cylinder 12 are open. The lower inner cylinder 12 has a first crystal pulling channel arranged along the axial direction of the lower inner cylinder 12. Both the upper and lower ends of the upper outer cylinder 21 and the upper inner cylinder 22 are open. The upper inner cylinder 22 has a second crystal pulling channel arranged along the axial direction of the upper inner cylinder 22.

[0024] Specifically, a plurality of lifting plates 3 are evenly distributed along the circumferential direction at the upper end of the annular support portion 111. Lifting holes for lifting are provided on the lifting plates 3. In this embodiment, the number of the lifting plates 3 is three and they are evenly distributed along the circumferential direction of the annular support portion 111, which increases the stability during lifting. The number of the lifting holes on each lifting plate 3 is two. Both the first heat insulation layer 13 and the second heat insulation layer 23 are soft felts. A receiving space for accommodating the first heat insulation layer 13 is provided between the lower outer cylinder 11 and the lower inner cylinder 12. The cross-section of the receiving space is similar to a right triangle. After filling the receiving space with soft felt, the temperature gradient can be increased and the drawing speed can be improved. It should be noted that the parts not detailed in this application are all prior arts.

[0025] More specifically, a first annular portion 212 extending outward is provided at the upper end of the upper outer cylinder 21, and a second annular portion 221 extending outward is provided at the upper end of the upper inner cylinder 22. The second annular portion 221 is located above the first annular portion 212.

[0026] In addition, the upper inner cylinder 22 includes a first tapered cylinder 222 and a second tapered cylinder 223 which are arranged in sequence from bottom to top along its axis. The large end of the first tapered cylinder 222 faces upward and is connected to the small end of the second tapered cylinder 223. The taper of the first tapered cylinder 222 is smaller than the taper of the second tapered cylinder 223.

[0027] Certainly, the present utility model is not limited to the above-described embodiments. Several other embodiments based on the design concept of the present utility model are provided below.

[0028] For example, in other embodiments, different from the above-described embodiments, as Figure 1 and Figure 2 shown, both the lower outer cylinder 11 and the lower inner cylinder 12 are tapered. The large ends of the lower outer cylinder 11 and the lower inner cylinder 12 face upward. The taper of the lower outer cylinder 11 is smaller than the taper of the lower inner cylinder 12.

[0029] It should be noted that the above embodiments are only used to illustrate the present utility model, but the present utility model is not limited to the above embodiments. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present utility model all fall within the protection scope of the present utility model.

Claims

1. A heat shield for a single crystal furnace, characterized in that: The heat shield comprises a lower heat shield (1) and an upper heat shield (2) arranged on the lower heat shield (1), wherein the lower heat shield (1) comprises a lower outer cylinder (11) and a lower inner cylinder (12) arranged inside the lower outer cylinder (11), and a first heat-insulating layer (13) is arranged between the lower outer cylinder (11) and the lower inner cylinder (12); an annular support portion (111) extending outward is arranged at the upper end of the lower outer cylinder (11), a plurality of hoisting plates (3) are evenly distributed along the circumferential direction at the upper end of the annular support portion (111), and hoisting holes for hoisting are arranged on the hoisting plates (3); The upper heat shield (2) comprises an upper outer cylinder (21) and an upper inner cylinder (22) arranged inside the upper outer cylinder (21); a second heat-insulating layer (23) is arranged between the upper outer cylinder (21) and the upper inner cylinder (22); an annular bottom (211) extending outward is arranged at the lower end of the upper outer cylinder (21); the upper inner cylinder (22) is located at the upper end of the annular bottom (211); the annular support portion (111) passes through the annular bottom (211) and extends into the upper inner cylinder (22) and contacts the inner wall of the upper inner cylinder (22); and the annular bottom (211) contacts the outer wall of the lower outer cylinder (11).

2. The heat shield of a single crystal furnace according to claim 1, characterized in that: The upper end of the upper outer cylinder (21) is provided with a first annular portion (212) extending outwards, and the upper end of the upper inner cylinder (22) is provided with a second annular portion (221) extending outwards, wherein the second annular portion (221) is located at the upper end of the first annular portion (212).

3. The heat shield of a single crystal furnace according to claim 1, characterized in that: The upper inner cylinder (22) comprises a first tapered cylinder (222) and a second tapered cylinder (223) which are arranged in sequence from bottom to top along the axial direction thereof.

4. The heat shield of a single crystal furnace according to claim 1, characterized in that: The large end of the first conical cylinder (222) faces upward and is connected to the small end of the second conical cylinder (223).

5. The heat shield of a single crystal furnace according to claim 1, characterized in that: The taper of the first tapered cylinder (222) is smaller than the taper of the second tapered cylinder (223).

6. The heat shield of a single crystal furnace according to claim 1, characterized in that: The first thermal insulation layer (13) and the second thermal insulation layer (23) are both soft felt.

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