Bottom heater for single crystal furnace

Abstract

The utility model discloses a bottom heater for a single crystal furnace. The bottom heater comprises an annular heating body and a foot plate for supporting the heating body, a group of inclined seams are formed in the wall surface of the heating body along the longitudinal direction; the angle between the inclined seam and the tangent line of the heating body on the annular wall surface at the inclined seam is 30-49 degrees, and a special seam design is adopted, so that airflow blockage driven by crucible rotation is avoided, and the temperature stability is improved. The special slot design increases the area of the heating area, improves the heating efficiency, ensures that the heating body is completely blocked at any slot in the direction perpendicular to the outer circle of the main heater, and the heating area forms an annular strip-shaped heating body, so that the area of the heating area is increased, and the uniformity of the heating temperature is improved.

Description

Technical Field

[0001] The utility model belongs to the field of single crystal silicon preparation, and particularly relates to a bottom heater for a single crystal furnace. Background Art

[0002] The heater of the single crystal furnace is an important component of the single crystal thermal field, and its main functions are twofold: one is to provide heat for melting silicon materials, and the other is to continuously and stably supply heat to the molten silicon liquid surface during the single crystal pulling process to ensure that the temperature of the crystallization interface is stable and meets the growth of single crystal silicon.

[0003] There are many design problems in the existing bottom heaters: (1) The adjusting resistors adopt a uniformly distributed slotted design. The width of the slotted is usually between 12 - 20 mm. Since there is no heating element at the slotted, the existing main heating ring-shaped heating elements are distributed at intervals with the slotted, resulting in poor temperature uniformity in the circumferential direction; (2) The slotted is vertically directed towards the center of the heater. There are crucible skirts and quartz crucibles arranged at the center of the heater, and the three are installed concentrically. During the actual crystal pulling process, after the crucible rotation is started, the crucible skirts and quartz crucibles rotate, driving the air flow. The slotted of the heater is perpendicular to the air flow direction, resulting in air flow obstruction, affecting the stability of the furnace table temperature, and further affecting the growth of single crystal silicon. Summary of the Invention

[0004] Purpose of the utility model: The technical problem to be solved by the utility model is to provide a bottom heater with a special slotted design to avoid air flow obstruction and improve temperature stability in view of the deficiencies of the existing technology.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0006] A bottom heater for a single crystal furnace includes an annular heating element and a foot plate for supporting the heating element; a group of inclined slots are arranged longitudinally on the wall surface of the heating element; the angle between the inclined slot and the tangent of the annular wall surface of the heating element at the inclined slot is 30 - 49 degrees.

[0007] Preferably, the angle between the inclined slot and the tangent of the annular wall surface of the heating element at the inclined slot is 45 degrees.

[0008] Further, the inclined slot includes a front wall surface and a rear wall surface, and the front and rear wall surfaces are parallel to each other; in the cross section, the front wall surface intersects the outer wall of the heating element at point a, and the rear wall surface intersects the inner wall of the heating element at point b. The connecting line between point a and the center of the heating element passes through the rear wall surface, and the connecting line between point b and the center of the heating element passes through the front wall surface.

[0009] More preferably, in the cross section, the front wall surface intersects the outer wall of the heating element at point a, and the rear wall surface intersects the inner wall of the heating element at point b. The connecting line between point a and point b passes through the center of the heating element.

[0010] Specifically, the inclined seams include a lower inclined seam and an upper inclined seam that are grooved upward and downward respectively, and the lower inclined seam and the upper inclined seam are arranged at intervals in sequence.

[0011] Further, the distance between the top notch of the lower inclined seam and the extension of the upper arm of the heating element is 220 - 240 mm; the distance between the bottom notch of the upper inclined seam and the extension of the lower arm of the heating element is 220 - 240 mm.

[0012] Further, the slot widths of the lower inclined seam and the upper inclined seam are 14 - 24 mm respectively.

[0013] Further, the inner diameter of the heating element is 1036 - 1048 mm, and the wall thickness of the heating element is 20 - 28 mm.

[0014] Further, there is a group of foot plates symmetrically arranged at the bottom of the heating element for supporting the heating element.

[0015] Further, the foot plate is L-shaped and is fixed to the outer wall surface of the heating element through a group of bolts at the top. Beneficial effects

[0016] The bottom heater of the present utility model adopts a special slotting design, which avoids the obstruction of the air flow driven by the crucible rotation and improves the temperature stability. The special slotting design increases the heating area and improves the heating efficiency, ensuring that the heating element is completely blocked in the vertical direction of the outer circle of the main heating at any slotted position, and the heating area forms an annular strip-shaped heating element, increasing the heating area and improving the uniformity of the heating temperature. Description of the drawings

[0017] The following further specifically describes the present utility model in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present utility model will become clearer.

[0018] Figure 1 is a three-dimensional structural schematic diagram of the bottom heater.

[0019] Figure 2 is a front view of the bottom heater.

[0020] Figure 3 is a side view of the bottom heater.

[0021] Figure 4 is a structural schematic diagram of the heating element.

[0022] Figure 5 is a top view of the inclined seams of the heating element and its wall.

[0023] Figure 6 is a state diagram when the line connecting point a and point b passes through the center of the heating element.

[0024] Among them, each reference numeral represents respectively:

[0025] 1 - heating element; 2 - foot plate; 3 - inclined slit; 301 - front wall surface; 302 - rear wall surface; 303 - lower inclined slit; 304 - upper inclined slit; 4 - bolt. Detailed implementation manners

[0026] The present utility model can be better understood according to the following embodiments.

[0027] The structures, ratios, sizes, etc. shown in the accompanying drawings of the specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the implementation conditions of the present utility model. Therefore, they do not have technical essential meanings. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the present utility model can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present utility model. At the same time, the terms such as "upper", "lower", "front", "rear", "middle" and the like cited in this specification are only for the convenience of clear narration, and are not used to limit the implementation scope of the present utility model. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the implementable scope of the present utility model.

[0028] Combined with Figures 1 to 3 As shown, the bottom heater for a single crystal furnace of the present utility model includes an annular heating element 1 and a foot plate 2 for supporting the heating element 1; a group of inclined slits 3 are arranged longitudinally on the wall surface of the heating element 1; the angle between the inclined slit 3 and the tangent of the annular wall surface of the heating element 1 at the inclined slit 3 is 30 - 49 degrees.

[0029] In a preferred case, the angle between the inclined slit 3 and the tangent of the annular wall surface of the heating element 1 at the inclined slit 3 is 45 degrees.

[0030] Combined with Figures 4 to 6 As shown, in this embodiment, the inclined slit 3 includes a front wall surface 301 and a rear wall surface 302, and the front and rear wall surfaces are parallel to each other; in the cross section, the front wall surface 301 intersects the outer wall 101 of the heating element 1 at point a, and the rear wall surface 302 intersects the inner wall 102 of the heating element 1 at point b. The connection line between point a and the center of the heating element 1 passes through the rear wall surface 302, and the connection line between point b and the center of the heating element 1 passes through the front wall surface 301.

[0031] In a preferred embodiment, the connection line between point a and point b passes through the center of the heating element 1.

[0032] In this embodiment, the inclined slit 3 includes a lower inclined slit 303 and an upper inclined slit 304 which are respectively grooved upward and downward, and the lower inclined slit 303 and the upper inclined slit 304 are arranged at intervals in sequence.

[0033] In this embodiment, the distance between the top notch of the lower inclined slot 303 and the extension of the upper arm of the heating element 1 is 228 mm; the distance between the bottom notch of the upper inclined slot 304 and the extension of the lower arm of the heating element 1 is 228 mm.

[0034] In this embodiment, the slot widths of the lower inclined slot 303 and the upper inclined slot 304 are 16 mm respectively.

[0035] In this embodiment, the inner diameter of the heating element 1 is 1039 mm, and the wall thickness of the heating element 1 is 26 mm.

[0036] In this embodiment, there is a set of foot plates 2, which are symmetrically arranged at the bottom of the heating element 1 respectively for supporting the heating element 1.

[0037] In this embodiment, the foot plate 2 is L-shaped, and the top is fixed to the outer wall surface of the heating element 1 through a set of bolts 4.

[0038] The bottom heater of the present utility model adopts a split design of the circular ring heating element 1 and the foot plate 2. Two positions for installing the heater foot plates 2 are symmetrically reserved on the heating element 1. Four screw holes are evenly distributed at the foot plate 2, which match the heater foot plate. Each single foot plate is fixed to the heating element 1 with four carbon-carbon bolts 4. The heating element 1 adopts a special slot-opening design. The slot-opening angle and the tangent are preferably at an included angle of 45 degrees (the general range is 30 - 49 degrees). When the heating element 1 is actually used, the heat radiated is circumferentially directed towards the center of the heater. When the 45-degree slot-opening design is adopted, it can ensure that points a and b completely coincide, and it can ensure that the heating element 1 is completely blocked in the horizontal direction of the outer circle at any slot-opening position. On the one hand, it increases the area of the heating zone and improves the heating efficiency. On the other hand, it realizes the annular strip heating of the entire heating element 1 and improves the uniformity of the heating temperature. In addition, the 45-degree slot-opening design enables the crucible to rotate during the crystal pulling process, and the crucible wall and the quartz crucible rotate after the crucible rotation is started, driving the air flow. The slot of the heater forms a 45-degree angle with the air flow direction, and the air flow is smoothly discharged from the 45-degree slot, avoiding the air flow being blocked by the main heating slot due to the air flow impact caused by the crucible rotation, and thus achieving the purpose of improving the temperature stability of the furnace platform.

[0039] The present utility model provides an idea and method for a bottom heater of a single crystal furnace. There are many methods and ways to specifically implement this technical solution. The above description is only the preferred embodiment of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present utility model, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present utility model. Each component not clearly defined in this embodiment can be implemented by the existing technology.

Claims

1. A bottom heater for a single crystal furnace, characterized in that: The heating device comprises an annular heating body (1) and a foot plate (2) for supporting the heating body (1); a group of oblique slits (3) are provided on the wall surface of the heating body (1) along the longitudinal direction; an angle between the oblique slits (3) and a tangent line of the annular wall surface of the heating body (1) at the oblique slits (3) is 30-49 degrees.

2. The bottom heater for a single crystal furnace according to claim 1, characterized in that: The angle between the inclined slit (3) and the tangent line of the annular wall surface of the heating body (1) at the inclined slit (3) is 45 degrees.

3. The bottom heater for a single crystal furnace according to claim 1, characterized in that: The oblique slit (3) comprises a front wall surface (301) and a rear wall surface (302), the front and rear wall surfaces being parallel to each other; in cross section, the front wall surface (301) intersects with the outer wall (101) of the heating body (1) at point a, the rear wall surface (302) intersects with the inner wall (102) of the heating body (1) at point b, a line connecting point a and the center of the heating body (1) passes through the rear wall surface (302), and a line connecting point b and the center of the heating body (1) passes through the front wall surface (301).

4. The bottom heater for a single crystal furnace according to claim 1, characterized in that: The oblique slit (3) comprises a front wall surface (301) and a rear wall surface (302), the front and rear wall surfaces being parallel to each other; in a cross section, the front wall surface (301) intersects with an outer wall (101) of the heating body (1) at point a, the rear wall surface (302) intersects with an inner wall (102) of the heating body (1) at point b, and a line connecting point a and point b passes through the center of a circle of the heating body (1).

5. The bottom heater for a single crystal furnace according to claim 1, characterized in that: The oblique slit (3) comprises a lower oblique slit (303) and an upper oblique slit (304) which are respectively grooved upward and downward, and the lower oblique slit (303) and the upper oblique slit (304) are arranged in sequence and at intervals.

6. The bottom heater for a single crystal furnace according to claim 5, characterized in that: The distance between the top notch of the lower oblique slit (303) and the upper arm extension of the heating body (1) is 220-240 mm; the distance between the bottom notch of the upper oblique slit (304) and the lower arm extension of the heating body (1) is 220-240 mm.

7. The bottom heater for a single crystal furnace according to claim 5, characterized in that: The opening widths of the lower oblique seam (303) and the upper oblique seam (304) are respectively 14-24 mm.

8. The bottom heater for a single crystal furnace according to claim 5, characterized in that: The inner diameter of the heating body (1) is 1036-1048 mm, and the wall thickness of the heating body (1) is 20-28 mm.

9. The bottom heater for a single crystal furnace according to claim 1, characterized in that: The foot plates (2) are a group and are symmetrically arranged at the bottom of the heating body (1) and are used to support the heating body (1).

10. The bottom heater for a single crystal furnace according to claim 9, characterized in that: The foot plate (2) is L-shaped, and the top is fixed to the outer wall surface of the heating body (1) by a group of bolts (4).

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