Heater for monocrystalline silicon thermal field

Abstract

The utility model provides a heater for a monocrystalline silicon thermal field, which relates to the technical field of monocrystalline silicon production equipment and comprises a heating ring used for conducting electricity, heating and providing heat for a quartz crucible; the first notches are formed in the heating ring from top to bottom, and the multiple first notches are evenly distributed in the circumferential direction of the heating ring; the second notches are formed in the heating ring from bottom to top, and the multiple second notches are evenly distributed in the circumferential direction of the heating ring; the supporting assembly is used for splicing the heating ring and transmitting current generated by the electrode of the single crystal furnace to the heating ring; wherein the depth of each first notch is smaller than that of each second notch, and one second notch is formed between every two adjacent first notches, so that the heating ring can provide a thermal field with a temperature gradient to heat the quartz crucible during heating.

Description

Technical Field

[0001] The utility model relates to the technical field of single crystal silicon production equipment, in particular to a heater for a single crystal silicon thermal field. Background Art

[0002] In the process of growing silicon single crystals by the Czochralski method, the quality of the single crystal silicon rod is related to the content of impurities such as carbon and oxygen. The oxygen mainly comes from the reaction between the silicon liquid and the bottom of the quartz crucible. That is, in the process of pulling the silicon liquid into a single crystal silicon rod, the oxygen element will enter the single crystal silicon rod to form impurities. The intensity of the reaction between the silicon liquid and the bottom of the quartz crucible is positively correlated with the amount of heat radiated by the heater to the quartz crucible.

[0003] During the process of pulling single crystal silicon, the crushed high-purity polysilicon material in the quartz crucible needs to be heated and melted first. This step is completed inside the single crystal furnace, and the heating of the quartz crucible requires the heat radiated by the heater outside the quartz crucible that is used to support the quartz crucible. The bottom of the heater is connected to the electrode in the single crystal furnace. The current conducts and generates heat on the heater, which can heat the quartz crucible and melt the high-purity polysilicon material, thereby completing the subsequent single crystal silicon pulling operation.

[0004] In the heating process of the above-mentioned quartz crucible, the heater used has the following defects:

[0005] 1. The heating area is uneven. For the current heaters, most of the heating coils are spliced, which will cause uneven distribution of the heating area on the cross section of the heating coil, which will also lead to unstable crystal pulling of single crystal silicon. In addition, the heating coil of some heater products will adopt an integrated molding structure, but the opening depth of the heating coil is not appropriate, which will also cause the problem of uneven heating area;

[0006] 2. There is no thermal field temperature gradient. Since the pulling of single crystal silicon needs to avoid the participation of oxygen elements, and the temperature on the legs of the current heater is not much different from the temperature of its heating ring, it causes a violent reaction at the bottom of the quartz crucible and produces oxygen elements, affecting the quality of single crystal silicon. Utility Model Content

[0007] In order to solve the problems of uneven heating area on the heater and lack of thermal field temperature gradient, the utility model provides a heater for a single crystal silicon thermal field, which enables the single crystal silicon thermal field to have a reasonable temperature gradient, reduces the oxygen content in the single crystal silicon product after molding, and improves the quality of the single crystal silicon product.

[0008] The technical solution adopted by the utility model is:

[0009] A heater for a single crystal silicon thermal field is provided, comprising: a heating coil for conducting heat and providing heat to a quartz crucible; a first notch, which is opened on the heating coil from top to bottom, and a plurality of the first notches are evenly distributed along the circumference of the heating coil; a second notch, which is opened on the heating coil from bottom to top, and a plurality of the second notches are evenly distributed along the circumference of the heating coil; a supporting assembly, which is used to splice the heating coils and transfer the current generated by the single crystal furnace electrode to the heating coil; wherein the depth of each first notch is less than the depth of each second notch, and a second notch is provided between every two adjacent first notches.

[0010] In some embodiments of the present invention, the spacing between each first notch and the second notches on two adjacent sides is equal.

[0011] In some embodiments of the present invention, the number of the first notches and the number of the second notches are both 16-26.

[0012] In some embodiments of the utility model, the support assembly includes a pair of vertical plates arranged corresponding to the single crystal furnace electrodes, and the vertical plates are fixedly connected to the heating coil to support the heating coil.

[0013] In some embodiments of the utility model, a foot plate extending horizontally toward the center of the heating coil is provided on the free end of each vertical plate, which is used to connect the single crystal furnace electrode and transmit current to the heating coil.

[0014] In some embodiments of the present invention, the width of the upright plate and the foot plate are both 130 mm-170 mm.

[0015] In some embodiments of the present invention, the thickness of the foot plate is 50 mm-70 mm.

[0016] In some embodiments of the utility model, the connection between the vertical plate and the foot plate facing the heating coil is rounded, and the radius of the rounded corner is 25mm-70mm.

[0017] The beneficial effects of the utility model are:

[0018] 1. The heating coil is provided with a first notch and a second notch at equal intervals at the top and bottom of the heating coil along its circumferential direction. Since the depth of the first notch is less than that of the second notch, the conductive areas of the upper and lower sides of the heating coil sidewall in contact with the quartz crucible are different. According to the resistance calculation formula, when the conductive material is constant, the smaller the conductive area, the greater the resistance, and vice versa. This makes the resistance at the top of the heating coil smaller and the resistance at the bottom larger. The generated heat is concentrated on the top of the heating coil. Combined with the support assembly spliced ​​on the heating coil, the heating coil generates heat to form a temperature gradient, which is convenient for the stability of single crystal silicon pulling.

[0019] 2. The adjacent first notches and the adjacent second notches are opened at equal intervals, and the first notches and the second notches are staggered in sequence, so that there will be no uneven heating in the cross section of the heating ring in the circumferential direction, thereby avoiding uneven heating in all directions during single crystal silicon pulling and causing unstable single crystal silicon pulling, which affects the quality of the single crystal silicon pulled. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a schematic diagram of the three-dimensional structure of a heater for a single crystal silicon thermal field;

[0022] Figure 2 It is a front view of a heater for a single crystal silicon thermal field;

[0023] Figure 3 for Figure 1 A local enlarged schematic diagram of the middle A;

[0024] Figure 4 Visualization of a common heater simulated by Comsol software;

[0025] Figure 5 This is a visualization diagram of the heater of the utility model simulated by Comsol software.

[0026] Reference numerals:

[0027] 1-heating ring, 10-first notch, 11-second notch, 12 fixing hole, 13 first through hole, 14-first bolt;

[0028] 2-vertical plate, 20-foot plate, 21-second through hole, 22-second bolt, 23-rounded corner structure. DETAILED DESCRIPTION

[0029] 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", "axial", "radial", "circumferential" 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.

[0030] The disclosure below provides many different embodiments or examples to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention.

[0031] The embodiments of the utility model are described in detail below with reference to the accompanying drawings.

[0032] Example

[0033] like Figure 1 As shown, this embodiment provides a heater for a single crystal silicon thermal field, comprising:

[0034] The heating coil 1 is used for conducting heat and providing heat to the quartz crucible;

[0035] The first notch 10 is formed on the heating coil 1 from top to bottom, and a plurality of notches are evenly distributed along the circumference of the heating coil 1;

[0036] The second notches 11 are formed on the heating coil 1 from bottom to top, and a plurality of the notches are evenly distributed along the circumference of the heating coil 1;

[0037] A support assembly, used for splicing the heating coil 1 and transmitting the current generated by the single crystal furnace electrode to the heating coil 1;

[0038] The depth of each first notch 10 is smaller than the depth of each second notch 11 , and one second notch 11 is disposed between every two adjacent first notches 10 .

[0039] The heating coil 1 is mainly used to support and place the quartz crucible, and when the current is transmitted, the heating coil 1 itself generates heat to form a single crystal silicon thermal field, thereby achieving a heating effect on the quartz crucible on the heating coil 1. Figure 4 and Figure 5As shown, the red areas in the two figures are all high-temperature areas, and the blue areas are all relatively low-temperature areas. It can be concluded that the main heating area of ​​the heater of the utility model is concentrated on the upper part of the heating coil, and an obvious temperature gradient is formed from top to bottom as a whole, which is better than the thermal field distribution formed when ordinary heaters are heated. The heating coil 1 and the support component are both made of materials such as graphite or carbon-carbon composite materials. The support component is spliced ​​with the heating coil 1 to fix and support the heating coil 1 and transfer the current generated by the single crystal furnace electrode to the heating coil 1 for heating.

[0040] When in use, the quartz crucible is placed on the heating coil 1, and the electrode at the bottom of the single crystal furnace generates current, which flows through the support assembly to the inside of the heating coil 1, so that the heating coil 1 generates heat and heats the quartz crucible. When the heating coil 1 is heated, since the depth of the first notch 10 is less than the depth of the second notch 11, the conductive area of ​​the upper part of the heating coil 1 is less than the conductive area of ​​the lower part. According to the calculation formula of the resistance law R=ρL⁄S, under the condition of the same conductor material, the smaller the conductive area, the greater the resistance. According to the resistance heating calculation formula Q=I^2 Rt, it can be obtained that the heat generated by the upper part of the heating coil 1 is greater than the heat generated by the lower part. Combined with the temperature after the support assembly is heated, a temperature gradient is formed to prevent the bottom of the quartz crucible from being subjected to a high temperature and reacting violently, reduce the generation of oxygen content in the silicon solution, and improve the quality of single crystal silicon molding; in addition, the first notch 10 and the second notch 11 staggered in the circumferential direction of the heating coil 1 make the top high heat zone and the bottom low heat zone of the heating coil 1 evenly distributed, avoiding the uneven distribution of heat provided by the cross section of the heating coil 1 in the circumferential direction.

[0041] Further, such as Figure 1 and Figure 2 As shown, the distance between each first notch 10 and the second notches 11 on both sides thereof is equal.

[0042] The first notch 10 on the heating coil 1 is located between two adjacent second notches 11, and the spacing between the first notch 10 and the second notches 11 on both sides is equal, that is, based on the projection of the front view of the heating coil 1, it can be concluded that the first notch 10 is located on the perpendicular bisector of the shortest connecting line between two adjacent second notches 11.

[0043] During use, when the current passes through the supporting component and enters the heating coil 1, heat will be generated according to the different conductive areas. If the position of the first recess 10 is not in the middle of the distance between two adjacent second recesses 11, the distance between the first recess 10 and the adjacent second recesses 11 on both sides will be different, resulting in uneven heat distribution on the cross section of the heating coil 1 along its circumferential direction, which will affect the instability of the single crystal silicon formed by subsequent crystal pulling.

[0044] Furthermore, the number of the first notches 10 and the number of the second notches 11 are both 16-26.

[0045] In this embodiment, the heating coil 1 is a circular ring, and the first recess 10 opened on the top and the second recess 11 opened on the bottom divide the heating coil 1 into a plurality of U-shaped connecting blocks, and the adjacent U-shaped connecting blocks are connected end to end in sequence to form an integral structure. It is worth noting that since the depth of the first recess 10 is less than the depth of the second recess 11, the conductive area of ​​the U-shaped connecting block near the upper part of the heating coil 1 is smaller than the conductive area of ​​the U-shaped connecting block near the lower part of the heating coil 1. The purpose is to concentrate the heating area of ​​the heating coil 1 on the upper part of the heating coil 1 and form a temperature gradient along the axial direction of the heating coil 1. The number of U-shaped connecting blocks located on the upper part of the heating coil 1 is consistent with the number of the first recess 10 and the second recess 11, which is between 16 and 26, and is determined according to different sizes of quartz crucibles.

[0046] When in use, the first recess 10 and the second recess 11 can be formulated into heaters with different aperture sizes according to different quartz crucible sizes, thereby improving the application range of the product.

[0047] Further, such as Figure 1 and Figure 2 As shown, the support assembly includes a pair of vertical plates 2 arranged corresponding to the single crystal furnace electrodes, and the vertical plates 2 are fixedly connected to the heating coil 1 to support the heating coil 1.

[0048] At least four first through holes are provided on the side where the vertical plate 2 is connected to the heating coil 1, and fixing holes corresponding to the first through holes are provided on the side wall of the heating coil 1. The first bolts 14 are rotatably connected to the fixing holes and the vertical plate 2 is fixed to the heating coil 1 through the first through holes. The first bolts 14 are made of materials such as graphite or carbon-carbon materials. It is worth noting that at the joint position of the vertical plate 2 and the heating coil 1, the side of the vertical plate 2 opposite to its own joint surface is not flush with the outer wall of the heating coil 1, that is, at the joint position, the sum of the thickness of the vertical plate 2 plus the adjusted thickness of the heating coil 1 is greater than the original thickness of the heating coil 1, generally greater than 28 mm, in order to reduce the current impact and avoid sparking.

[0049] When in use, the vertical plate 2 supports the heating coil 1 in the single crystal furnace and transmits the current generated by the single crystal furnace electrode to the heating coil 1. In this embodiment, the width of the vertical plate 2 is adjusted compared with the existing product and becomes wider, that is, the conductive area is increased, the heat generation is reduced, and the high temperature area on the vertical plate 2 is avoided, which causes the bottom of the quartz crucible to violently produce a large amount of oxygen elements to affect the quality of the single crystal silicon.

[0050] Further, such as Figure 1 and Figure 2As shown, a foot plate 20 extending horizontally toward the center of the heating coil 1 is provided on the free end of each vertical plate 2 for connecting to the single crystal furnace electrode and transmitting current to the heating coil 1 .

[0051] A foot plate 20 is vertically arranged on the inner side wall of the vertical plate 2 facing the heating coil 1. The foot plate 20 is used to improve the support stability of the heating coil 1 in the single crystal furnace, and the foot plate 20 is also used to connect the electrode at the bottom of the single crystal furnace. A second through hole 21 is opened on the foot plate 20, and the axis of the second through hole 21 is parallel to the axis of the heating coil 1. The second bolt 22 is used to connect the foot plate 20 to the electrode of the single crystal furnace inside the second through hole 21, so that the current generated by the single crystal furnace can enter the heating coil 1 through the foot plate 20 and the vertical plate 2 in turn.

[0052] When in use, the foot plate 20 is connected to the single crystal furnace electrode through the second bolt 22, which plays a role in supporting the heating coil 1 and also transmits current to the heating coil 1. It is worth noting that in this embodiment, the thickness of the foot plate 20 is adjusted. Compared with the supporting components of the existing heating coil 1, the increase in thickness can improve the support stability while increasing the conductive area, making the resistance smaller and reducing the heat generation. Its purpose is also to avoid a violent reaction at the bottom of the quartz crucible to produce a large amount of oxygen elements and affect the stability of the single crystal silicon.

[0053] Furthermore, the widths of the upright plate 2 and the foot plate 20 are both 130 mm to 170 mm.

[0054] The width of the vertical plate 2 and the foot plate 20 in the ordinary heater is relatively small, about 100 mm. In the utility model, the width of the vertical plate 2 and the foot plate 20 is increased to 130 mm-170 mm, that is, Figure 1 In a, the widened upright plate 2 and the foot plate 20 increase the conductive area, reduce the resistance, and reduce the heat generation, thereby preventing the bottom of the quartz crucible from being overheated and producing a large amount of oxygen, which affects the quality of single crystal silicon molding.

[0055] It is worth noting that Figure 1 and Figure 3 As shown, in this embodiment, the width of the upper part of the vertical plate 2 at the joint position with the heating coil 1 is smaller than the width of the middle and lower part of the vertical plate 2, and the width of the joint position at the top of the vertical plate 2 is equal to the width of the U-shaped connecting block mentioned above, as shown in FIG. Figure 1 d and Figure 3c in the figure corresponds to the width of the upper joint of the vertical plate 2, and d corresponds to the width of the U-shaped connection block, that is, there is a fault in the vertical plate 2 from the top to the middle, and this fault makes the upper width of the vertical plate 2 smaller than the width of the remaining parts, from which we can derive a formula, a>c=d. Compared with the width of the vertical plate and the foot plate in the ordinary heater, which are the same as the width of the U-shaped connection block, the optimized vertical plate 2 with a fault can make the vertical plate have a temperature gradient when conducting heat, so that the heating area is more concentrated in the upper part of the overall heater.

[0056] Furthermore, the thickness of the foot plate 20 is 50 mm-70 mm.

[0057] The thickness of the foot plate in the ordinary heater is 40mm-45mm, and the thickness of the foot plate 20 in the heater of the utility model is thickened to between 50mm-70mm, that is, Figure 1 b in the figure, and according to the resistance law and the resistance heating calculation formula, it can be concluded that the conductive area increases, the resistance decreases, the heat generation decreases, the bottom of the quartz crucible is heated lower, less oxides are produced, and the oxygen concentration is reduced, which reduces the oxygen content in the single crystal silicon and improves the quality of the formed single crystal silicon. For details, refer to Figure 5 shown.

[0058] Further, such as Figure 1 and Figure 2 As shown, the connection between the vertical plate 2 and the foot plate 20 facing the heating coil 1 is rounded, and the radius of the rounded corner is 25mm-70mm.

[0059] The connection between the vertical plate 2 and the foot plate 20 has a fillet with a larger radius. Compared with the fillet with a radius of 10mm at the foot plate 20 in ordinary heaters, the foot plate 20 in the utility model has a fillet with a radius between 20mm-70mm, which can reduce the current impact at the chamfered position and effectively avoid the occurrence of ignition of the foot plate 20 due to overheating.

[0060] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. In the absence of conflicts, the embodiments of the present application and the features in the embodiments may be arbitrarily combined with each other. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A heater for a single crystal silicon thermal field, characterized in that: include: The heating ring is used for conducting heat and providing heat to the quartz crucible; A first notch is formed on the heating ring from top to bottom, and a plurality of first notches are evenly distributed along the circumference of the heating ring; The second notch is opened on the heating ring from bottom to top, and a plurality of the second notches are evenly distributed along the circumference of the heating ring; A support assembly, used for splicing the heating coil and transferring the current generated by the single crystal furnace electrode to the heating coil; The depth of each of the first notches is smaller than the depth of each of the second notches, and a second notch is arranged between every two adjacent first notches.

2. The single crystal silicon thermal field heater according to claim 1, characterized in that: The distance between each of the first notches and the second notches on two adjacent sides is equal.

3. The single crystal silicon thermal field heater according to claim 2, characterized in that: The number of the first notches and the number of the second notches are both 16-26.

4. The single crystal silicon thermal field heater according to claim 3, characterized in that: The support assembly includes a pair of vertical plates arranged corresponding to the single crystal furnace electrodes, and the vertical plates are fixedly connected to the heating coil to support the heating coil.

5. The single crystal silicon thermal field heater according to claim 4, characterized in that: A foot plate extending horizontally toward the center of the heating coil is arranged on the free end of each of the vertical plates, and is used for connecting the single crystal furnace electrode and transmitting current to the heating coil.

6. The single crystal silicon thermal field heater according to claim 5, characterized in that: The widths of the upright plate and the foot plate are both 130mm-170mm.

7. The single crystal silicon thermal field heater according to claim 6, characterized in that: The thickness of the foot plate is 50mm-70mm.

8. The single crystal silicon thermal field heater according to claim 5, characterized in that: A connection between the vertical plate and the foot plate on the side facing the heating coil is rounded, and the radius of the rounded corner is 25mm-70mm.

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