Heater of single crystal furnace

Abstract

A heater of a single crystal furnace. The heater comprises a main heater, an auxiliary heater and a bottom heater, the auxiliary heater being located below the main heater. The main heater, the auxiliary heater and the bottom heater are respectively connected to electrodes of different power supplies. During a melting phase, the main heater, the auxiliary heater and the bottom heater heat a crucible at set powers; and during a crystal growth phase, the main heater allocates a power to the auxiliary heater so as to heat the crucible. During the melting phase, the main heater and the auxiliary heater heat the crucible from the side surface thereof, and the bottom heater heats the crucible from the bottom portion thereof. Thus, by means of increasing the power of the auxiliary heater, the upper limit of the power for melting is greatly improved, thereby effectively raising the melting temperature and improving the melting efficiency. After the auxiliary heater shares the power of the main heater, the temperature of the surface of the crucible is effectively reduced, so that the content of released oxygen is effectively reduced, and the content of oxygen entering a crystal rod is thus reduced, thereby greatly improving the quality of the crystal rod.

Description

Heater for single crystal furnace Technical Field

[0001] The invention belongs to the technical field of single crystal furnaces and relates to a heater of a single crystal furnace. Background Art

[0002] Currently, the photovoltaic industry uses a dual-heater solution for the growth of vertically pulled single crystals, namely the main heater and the bottom heater. When melting the material, the two heaters work simultaneously. During the crystal growth process, only the main heater works and the bottom heater does not participate. Normal crystal growth cannot be completed if the bottom heater is turned on.

[0003] The problem this brings is that when a single main heater is working, the local temperature of the crucible surface is high, and a large amount of oxygen is released, resulting in a large amount of oxygen entering the crystal rod, which cannot meet the requirements of silicon wafer products and has low battery conversion efficiency, especially for N-type silicon wafers.

[0004] When two heaters are used to melt the material and the power is given to the maximum, the melting efficiency is relatively low, which delays working time.

[0005] Summary of the Invention

[0006] In order to overcome at least one deficiency of the prior art, the present invention provides a heater for a single crystal furnace.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a heater of a single crystal furnace, comprising a main heater, a sub-heater and a bottom heater, the sub-heater being located below the main heater, the main heater, the sub-heater and the bottom heater being connected to different power supply electrodes respectively, in the melting stage, the main heater, the sub-heater and the bottom heater heating the crucible with set power, in the crystal growth stage, the sub-heater allocating the power of the main heater to heat the crucible.

[0008] Furthermore, before power distribution, the power of the main heater is set to A, and after power distribution, the power of the main heater is set to A1, and the power of the sub-heater is set to A2. A1 and A2 are less than A, and A1+A2=A.

[0009] Furthermore, during the melting stage, the sub-heater is located in the middle of the crucible; during the crystal growth stage, the distance between the sub-heater and the main heater is set to 20mm-40mm.

[0010] Furthermore, the main heater and the auxiliary heater are both cylindrical structures with openings at both ends, and the cylindrical structures are both composed of at least two heating units, and the crucible is located inside the cylindrical structure.

[0011] Furthermore, the main heater includes a main heating zone and a main heating footplate. There are two groups of main heating footplates. The main heating footplates are fixed in the main heating zone and connected to the main heating power supply electrodes.

[0012] Furthermore, the auxiliary heater includes an auxiliary heating zone and an auxiliary heating footplate. Two groups of auxiliary heating footplates are provided. The auxiliary heating footplates are fixed in the auxiliary heating zone and connected to the auxiliary heating power supply electrodes.

[0013] Furthermore, the auxiliary heating zone is also provided with a heating plate, and the heating plates are distributed around the main heating foot plate.

[0014] Furthermore, the two groups of main heating foot plates are respectively connected to the positive electrode and the negative electrode of the main heating power supply electrode.

[0015] Furthermore, the two groups of auxiliary heating foot plates are respectively connected to the positive pole and the negative pole of the auxiliary heating power supply electrode.

[0016] Furthermore, the bottom heater is provided with two groups of bottom electrode connecting posts, and the two groups of bottom electrode connecting posts are connected to the positive electrode and the negative electrode of the bottom heating power supply electrode.

[0017] In summary, the present invention is beneficial in that:

[0018] 1) In the melting stage of the present invention, the main heater and the auxiliary heater heat the side of the crucible, and the bottom heater heats the bottom of the crucible. By increasing the power of the auxiliary heater, the upper limit of the melting power is greatly improved, the melt temperature is effectively increased, and the melting efficiency is improved. At the same time, the main heater, auxiliary heater and bottom heater are respectively connected to different power electrodes to realize independent control, so that their power can be flexibly adjusted according to actual needs, so as to achieve the purpose of rapid melting. In the crystal growth stage, the auxiliary heater distributes the power of the main heater to reduce the power of the main heater, reduce the loss, and extend the service life of the heater. At the same time, the local temperature of the crucible is reduced, the reaction speed of the silicon liquid and the crucible is reduced, and the released oxygen content is effectively reduced, so that the oxygen content entering the crystal rod is reduced, which greatly improves the quality of the crystal rod. At the same time, the power value can be flexibly allocated according to actual needs to achieve the purpose of maximizing the reduction of oxygen content.

[0019] 2) The present invention controls the lifting and lowering of the sub-heater through a lifting structure to adjust the distance between the main heater and the sub-heater. During the melting stage, the lifting structure controls the movement of the sub-heater so that the sub-heater is located in the middle of the crucible, so that the heat generated by the sub-heater can be absorbed by the silicon liquid, thereby greatly improving the melting efficiency. During the crystal growth stage, the lifting structure controls the movement of the sub-heater so that the distance between the sub-heater and the main heater is controlled at a set distance. At this time, the sub-heater is closest to the upper part of the crucible. After the sub-heater shares the power of the main heater, the temperature of the crucible surface is effectively reduced, and the released oxygen content is effectively reduced, thereby reducing the oxygen content entering the crystal rod, greatly improving the quality of the crystal rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a schematic diagram of a heater according to the present invention.

[0021] FIG2 is a schematic diagram of a heater according to the present invention.

[0022] FIG3 is a bottom view of the heater of the present invention.

[0023] Markings in the figure: main heater 1, auxiliary heater 2, bottom heater 3, main heating zone 11, main heating foot plate 12, main electrode connecting column 13, auxiliary heating zone 21, auxiliary heating foot plate 22, auxiliary electrode connecting column 23, heating plate 24, bottom electrode connecting column 33. DETAILED DESCRIPTION

[0024] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0025] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0026] All directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, horizontal, vertical...) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0027] Due to installation errors and other reasons, the parallel relationship referred to in the embodiments of the present invention may actually be an approximately parallel relationship, and the perpendicular relationship may actually be an approximately perpendicular relationship.

[0028] Example 1:

[0029] As shown in Figures 1-3, a heater for a single crystal furnace includes a main heater 1, a sub-heater 2 and a bottom heater 3. The sub-heater 2 is located below the main heater 1. The main heater 1, the sub-heater 2 and the bottom heater 3 are respectively connected to different power supply electrodes. In the melting stage, the main heater 1, the sub-heater 2 and the bottom heater 3 heat the crucible with set power. In the crystal growth stage, the sub-heater 2 distributes the power of the main heater 1 to heat the crucible.

[0030] In this embodiment, the different power supply electrodes include a main heating power supply electrode, a secondary heating power supply electrode, and a bottom heating power supply electrode.

[0031] The main heater 1 and the auxiliary heater 2 are both cylindrical structures with openings at both ends. The cylindrical structures are composed of at least two heating units. The crucible is located inside the cylindrical structure. The main heater 1 and the auxiliary heater 2 are located in the circumferential direction of the crucible to heat its sides, and the bottom heater 3 is located at the bottom of the crucible to heat its bottom.

[0032] The main heater 1 includes a main heating zone 11 and a main heating foot plate 12. The main heating foot plate 12 is fixed to the main heating zone 11. There are two groups of main heating foot plates 12. The main heating foot plates 12 are symmetrically distributed with respect to the central axis of the main heating zone 11.

[0033] The main heating footplates 12 are connected to the main heating power supply electrodes, and the two groups of main heating footplates 12 are respectively connected to the positive electrode and the negative electrode of the main heating power supply electrodes.

[0034] The main heating foot plate 12 is connected to the main heating power supply electrode. Specifically:

[0035] The main heating foot plate 12 is set to an L-shaped structure. The main heating foot plate 12 includes a vertical forming plate and a horizontal forming plate. The vertical forming plate is connected to the main heating zone 11, and the horizontal forming plate is connected to the main electrode connecting column 13. The main electrode connecting column 13 is connected to the main heating power supply electrode.

[0036] The auxiliary heater 2 includes an auxiliary heating zone 21 and auxiliary heating foot plates 22. The auxiliary heating foot plates 22 are fixed to the auxiliary heating zone 21. There are two groups of auxiliary heating foot plates 22. The auxiliary heating foot plates 22 are symmetrically distributed with respect to the central axis of the auxiliary heating zone 21.

[0037] The auxiliary heating footplates 22 are connected to the auxiliary heating power supply electrodes, and the two groups of auxiliary heating footplates 22 are respectively connected to the positive pole and the negative pole of the auxiliary heating power supply electrodes.

[0038] The structure of the auxiliary heating footplate 22 is the same as that of the main heating footplate 12. The auxiliary heating footplate 22 is provided with an auxiliary electrode connecting column 23, and the auxiliary electrode connecting column 23 is connected to the auxiliary heating power supply electrode.

[0039] The auxiliary heating zone 21 is further provided with a heating plate 24 . The heating plate 24 is configured as a rectangular structure with one end open. The heating plates 24 are distributed around the main heating foot plate 12 .

[0040] The heating plate 24 is an integrated structure consisting of a horizontal plate and vertical plates symmetrically fixed at both ends of the horizontal plate. An inner cavity is formed between the horizontal plate and the two groups of vertical plates. The vertical plate is fixedly connected to the auxiliary heating zone 21, and the main heating foot plate 12 extends into the inner cavity, so that the horizontal plate and the two groups of vertical plates are distributed around the periphery of the main heating foot plate 12. The present application distributes the heating plates 24 around the main heating foot plate 12. Under the condition that the main heater 1 and the auxiliary heater 2 have the same outer diameter, the main heater 1 and the auxiliary heater 2 can be distributed up and down and the auxiliary heater 2 can move up and down. Compared with the existing technical solution of avoiding the main heater 1 by reducing the outer diameter of the auxiliary heater 2, the present application distributes the heating plates 24 around the main heating foot plate 12 to ensure that the main heater 1 and the auxiliary heater 2 are distributed under the same outer diameter, so that the auxiliary heater 2 has a larger heating area, and the distance between the main heater 1 and the auxiliary heater 2 and the crucible is consistent, effectively ensuring the heating effect of the crucible, while saving costs and achieving the purpose of separately controlling the main heater 1 and the auxiliary heater 2.

[0041] The bottom heater 3 is provided with two groups of bottom electrode connection posts 33 , which are connected to the positive and negative electrodes of the bottom heating power supply electrodes.

[0042] In this embodiment, the main heater 1, the auxiliary heater 2 and the bottom heater 3 are respectively connected to the main heating power electrode, the auxiliary heating power electrode and the bottom heating power electrode, so that the main heater 1, the auxiliary heater 2 and the bottom heater 3 can be used independently. In the melting stage, the main heater 1, the auxiliary heater 2 and the bottom heater 3 can heat the crucible according to the set power. In the crystal growth stage, the auxiliary heater 2 allocates the power of the main heater 1 to heat the crucible.

[0043] In the prior art, when the crucible is heated by the main heater and the bottom heater in the melting stage, for example, the power of the main heater is set to 100kw and the power of the bottom heater is set to 90kw, even when the power of the two heaters is given to the maximum, that is, 100kw+90kw, the maximum power is low, the melting efficiency is relatively low, and the working time is delayed. In the crystal growth stage, only the main heater heats the crucible, and the power of the main heater is set to A. The main heater heats the upper part of the crucible, causing the local temperature of the silicon liquid in the crucible to be high, and the oxygen content released is relatively high, resulting in a high oxygen content entering the crystal rod, which cannot meet the requirements of the silicon wafer product and the problem of low battery conversion efficiency, especially for N-type silicon wafers. In this embodiment, in the melting stage, the main heater 1 and the auxiliary heater 2 heat the side of the crucible, and the bottom heater 3 heats the bottom of the crucible. Even if the power of the main heater 1 and the bottom heater 3 is set to the same as the prior art, the increase in the power of the auxiliary heater 2 greatly improves the melting power. upper limit, effectively increases the melt temperature, improves the melting efficiency, and at the same time, the power of the main heater 1, the auxiliary heater 2 and the bottom heater 3 can be controlled independently. The power values ​​of the main heater 1, the auxiliary heater 2 and the bottom heater 3 can be flexibly adjusted according to actual needs to achieve the purpose of rapid melting. In the crystal growth stage, the auxiliary heater 2 allocates the power of the main heater 1 to reduce the power of the main heater 1. After the power distribution, the power of the main heater 1 is set to A1, and the power of the auxiliary heater 2 is set to A2. A1 and A2 are less than A, and A1+A2=A. The values ​​of A1 and A2 can be flexibly allocated according to actual needs to achieve the purpose of maximizing the reduction of oxygen content. Compared with the existing technology, the power of A1 and A2 is lower than the power of A, the loss is reduced, the service life of the heater can be extended, and at the same time the local temperature of the crucible is reduced, the reaction speed of the silicon liquid and the crucible is reduced, and the released oxygen content is effectively reduced, thereby reducing the oxygen content entering the crystal rod, greatly improving the quality of the crystal rod.

[0044] The heater also includes a lifting structure, which is arranged in the single crystal furnace and connected to the auxiliary heater 2. The lifting structure controls the lifting and lowering of the auxiliary heater 2 to adjust the distance between the main heater 1 and the auxiliary heater 2.

[0045] The lifting structure adopts a conventional structure. In this embodiment, the lifting structure adopts a liftable electrode, which controls the up and down movement of the auxiliary heater 2 .

[0046] During the melting stage, the lifting structure controls the movement of the sub-heater 2 so that the sub-heater 2 is located in the middle of the crucible, so that the heat generated by the sub-heater 2 can be absorbed by the silicon liquid, thereby greatly improving the melting efficiency.

[0047] During the crystal growth stage, the lifting structure controls the movement of the auxiliary heater 2 so that the distance between the auxiliary heater 2 and the main heater 1 is set to a set distance. The set distance can be 20mm-40mm. This distance is the minimum safety distance. At this distance, no spark will occur between the main heater 1 and the auxiliary heater 2, and the auxiliary heater 2 at this position is closest to the upper part of the crucible. After the auxiliary heater 2 shares the power of the main heater 1, the temperature of the crucible surface will decrease under the heating conditions of powers A1 and A2 compared to power A.

[0048] The distance between the sub-heater 2 and the main heater 1 refers to the distance between the upper end surface of the sub-heater 2 and the lower end surface of the main heater 1 .

[0049] Preferably, the height of the main heating zone 11 is set to H1, and the secondary heating zone 21 is set to H2. The values ​​of H1 and H2 can be flexibly adjusted according to actual needs, such as H1=150mm, H2=170mm, or H1=200mm, H2=220mm, or H1=180mm, H2=200mm, or H1=150mm, H2=200mm, etc.

[0050] As shown in Figure 3, the figure only shows one distribution method of the main electrode connecting column 13, the secondary electrode connecting column 23, and the bottom electrode connecting column 33, but in actual operation, the positions of the main electrode connecting column 13, the secondary electrode connecting column 23, and the bottom electrode connecting column 33 can be flexibly adjusted as needed.

[0051] Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

Claims

1. A heater for a single crystal furnace, characterized in that: It includes a main heater, a sub-heater and a bottom heater. The sub-heater is located below the main heater. The main heater, sub-heater and bottom heater are respectively connected to different power electrodes. In the melting stage, the main heater, sub-heater and bottom heater heat the crucible with set power. In the crystal growth stage, the sub-heater distributes the power of the main heater to heat the crucible.

2. The heater of a single crystal furnace according to claim 1, characterized in that: Before power distribution, the power of the main heater is set to A. After power distribution, the power of the main heater is set to A1, and the power of the auxiliary heater is set to A2. A1 and A2 are less than A, and A1+A2=A.

3. The heater of a single crystal furnace according to claim 1, characterized in that: During the melting stage, the auxiliary heater is located in the middle of the crucible; during the crystal growth stage, the distance between the auxiliary heater and the main heater is set to 20mm-40mm.

4. The heater of a single crystal furnace according to claim 1, characterized in that: The main heater and the auxiliary heater are both cylindrical structures with openings at both ends. The cylindrical structures are both composed of at least two heating units, and the crucible is located inside the cylindrical structures.

5. The heater of a single crystal furnace according to claim 1, characterized in that: The main heater includes a main heating zone and a main heating footplate. The main heating footplate is provided with two groups. The main heating footplate is fixed in the main heating zone and connected to the main heating power supply electrode.

6. The heater of a single crystal furnace according to claim 1, characterized in that: The auxiliary heater includes an auxiliary heating zone and an auxiliary heating footplate. Two groups of auxiliary heating footplates are provided. The auxiliary heating footplates are fixed in the auxiliary heating zone and connected to the auxiliary heating power supply electrodes.

7. The heater of a single crystal furnace according to claim 6, characterized in that: The auxiliary heating zone is further provided with a heating plate, which is distributed around the main heating foot plate.

8. The heater of a single crystal furnace according to claim 5, characterized in that: The two groups of main heating foot plates are respectively connected to the positive electrode and the negative electrode of the main heating power supply electrode.

9. The heater of a single crystal furnace according to claim 6, characterized in that: The two groups of auxiliary heating foot plates are respectively connected to the positive pole and the negative pole of the auxiliary heating power supply electrode.

10. The heater of a single crystal furnace according to claim 1, characterized in that: The bottom heater is provided with two groups of bottom electrode connecting posts, which are connected to the positive electrode and the negative electrode of the bottom heating power supply electrode.

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