Single crystal furnace thermal field with double-spiral heater

Abstract

The utility model provides a single crystal furnace thermal field with a double-helix heater, which comprises the double-helix heater arranged at the bottom of a crucible, and the double-helix structure is formed by circling two groups of heating pipes from bottom to top in a manner that the rotation radius is gradually reduced; the starting end of the lower part and the extension line of the upper circular platform intersect with the central axis of the heater to form a taper angle; the two groups of graphite electrodes are respectively connected to the starting end of the bottom of the double-helix structure; the main heater is attached to the inner wall of the cylindrical box body in a surrounding manner; the supporting rod is vertically mounted on the central axis of the cylindrical box body and penetrates through the crucible and the heater; the main heater and the heater at the bottom are used for heating together, so that the conditions of non-uniform temperature in the crucible and low heat efficiency are solved; the heating area of the heater of the three-dimensional double-helix structure is gradually reduced from bottom to top, a hierarchically differentiated heat radiation space is formed based on different distances between the heater and the crucible in the axial direction, and the problem that temperature gradient exists in the crucible is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of single crystal silicon, in particular to a single crystal furnace thermal field with a double spiral heater. Background Art

[0002] With the continuous development of single crystal furnace technology, the control and stabilization of the thermal field system is equivalent to stabilizing the single crystal yield and the quality of single crystal silicon rods. The bottom heater is an important part of the thermal field of the single crystal furnace. Its main function is to provide the heat required for crystal growth to promote crystal growth and optimize crystal quality. Traditional bottom heaters usually use resistance heating technology. The bottom heaters are all flat integrated or flat spliced. Thermal radiation is the main method to heat the quartz crucible melt and produce single crystal silicon rods.

[0003] The existing bottom heater technology is generally a flat bottom heater with a fixed shape. It lacks a side heating design, which will inevitably lead to a situation where the temperature of the upper part of the crucible is lower than that of the lower part. Secondly, the heat radiation source at the bottom is emitted in the same vertical direction to the bottom of the quartz crucible. Although the bottom of the quartz crucible is heated evenly temporarily, as the polysilicon melts and the single crystal is crystallized and pulled out, the solid-liquid surface and the axial temperature of the bottom begin to change. An example of the temperature gradient of the crucible caused by the existing flat bottom heater is shown in the attached figure. Figure 1 As shown in the figure, during the shoulder release stage, the heat of the crystal and the melt shows that the radial temperature of the bottom of the crucible gradually increases from the inside to the outside, and the axial temperature gradually decreases from the bottom to the top, indicating that the existing bottom heater will produce a change in temperature gradient, and excessive temperature gradient will eventually lead to crystal transformation, and the occurrence of crystal transformation is bound to lead to a change in product yield. In addition, the heat generation of the existing planar bottom heater is affected by space and structure, and providing long-term uniform heat radiation will cause high-temperature baking of the bottom graphite felt, entering the aging period early. Utility Model Content

[0004] The purpose of the utility model is to provide a single crystal furnace thermal field with a double spiral heater, so as to solve the problem in the prior art that the crucible has a large temperature gradient change due to the lack of side heating and the planar heater causes the crucible to have a large temperature gradient change, thereby causing crystal change, affecting the product yield, and also solves the problem that the existing planar heater cannot provide thermal radiation with a temperature gradient.

[0005] The technical solution of the utility model is as follows:

[0006] A single crystal furnace heat field with a double spiral heater, the single crystal furnace heat field is a cylindrical box with an internal cavity, accommodating the vertical placement and removal of the crucible, and also includes:

[0007] A double-helix heater is arranged at the bottom of the crucible, and the double-helix heater is a three-dimensional double-helix structure. The double-helix structure is composed of two groups of heating tubes spiraling from bottom to top in a decreasing rotation radius. The upper part of the double-helix structure is connected to a circular platform, and the lower starting end of the double-helix structure and the extension line of the upper circular platform intersect with the central axis of the heater to form a cone angle;

[0008] A graphite electrode, wherein the graphite electrode comprises two groups, each of which is connected to the bottom starting end of the double helix structure;

[0009] A main heater is attached to the inner wall of the cylindrical box in a surrounding manner, and the main heater is installed above the heater;

[0010] A supporting rod is vertically mounted on the central axis of the cylindrical box, and the supporting rod passes through the crucible and the heater.

[0011] Further preferably, it also includes bottom insulation, which is fixed on the inner bottom surface of the cylindrical box, and the graphite electrode is fixed on the upper part of the bottom insulation.

[0012] Further preferably, a hole reserved for an electrode bolt is respectively provided at the bottom starting end of the heater with a double helix structure, and the hole reserved for the electrode bolt is sleeved with the graphite electrode.

[0013] Further preferably, a circular supporting rod hole is provided in the middle of the circular platform on the upper part of the double helix structure, and the supporting rod is sleeved in the supporting rod hole.

[0014] Further preferably, the size of the cone angle depends on the lower radius of the double helix structure, the radius of the upper circular platform, and the height of the heater.

[0015] Compared with the prior art, the utility model has the following beneficial effects:

[0016] (1) The present disclosure provides a single crystal furnace thermal field with a double spiral heater, which is carried out in a cylindrical box. The design of the box can achieve the situation where the main heater on the side and the heater on the bottom are heated together, thereby solving the problem of uneven temperature in the crucible and low thermal efficiency caused by heating only at the bottom.

[0017] (2) In order to overcome the problem of temperature gradient in the crucible, the present invention also provides a three-dimensional double-helix structure heater, with the heating area decreasing from bottom to top, and forming a hierarchically differentiated heat radiation space based on different distances from the crucible in the axial direction, thereby solving the problem of temperature gradient caused by the prior art, that is, the problem of "increasing temperature from the center to the edge" at the bottom of the crucible. In addition, the three-dimensional double-helix structure can bring a larger heating area due to the presence of the side, thereby achieving higher thermal efficiency.

[0018] (3) The heat generation of the existing planar bottom heater is affected by the space and structure. Providing continuous and uniform heat radiation will cause high-temperature baking of the bottom graphite felt. In the technical solution disclosed in the present invention, the bottom heater is at a certain distance from the bottom graphite felt, which can prevent the graphite felt from entering the aging period prematurely. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 An example of a crucible temperature gradient caused by an existing planar bottom heater;

[0020] Figure 2 It is a schematic diagram of the overall structure of the utility model;

[0021] Figure 3 It is a structural schematic diagram of the heater of the utility model;

[0022] Figure 4 It is a schematic diagram of the top view of the structure of the heater of the utility model;

[0023] In the figure, 1. double helix heater, 1.1. reserved hole for electrode bolt, 1.2. hole for support rod, 1.3. double helix structure, 1.4. platform, 2. main heater, 3. graphite electrode, 4. bottom insulation, 5. support rod, 6. crucible, 7. cylindrical box, 8. cone angle α. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0025] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, similar words such as "one", "one" or "the" do not indicate quantity restrictions, but indicate that there is at least one. Similar words such as "include" or "comprise" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Similar words such as "connect" or "connected" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0026] Example 1

[0027] The utility model provides a single crystal furnace thermal field with a double spiral heater, such as Figures 2 to 4 As shown. The single crystal furnace thermal field is a cylindrical box 7 with an internal cavity, which accommodates the crucible to be placed vertically and taken out, and also includes: a double helix heater 1 arranged at the bottom of the crucible 6, the double helix heater 1 is a three-dimensional double helix structure 1.3, the double helix structure 1.3 is composed of two groups of heating tubes that spiral from bottom to top in a decreasing rotation radius, and the upper part of the double helix structure 1.3 is connected to a circular platform 1.4, and the lower starting end of the double helix structure 1.3 and the extension line of the upper circular platform 1.4 intersect with the central axis of the double helix heater 1 to form a cone angle α; the size of the cone angle α depends on the lower radius of the double helix structure 1.3, the radius of the upper circular platform 1.4, and the height of the double helix heater 1.

[0028] The graphite electrode 3 includes two groups, which are respectively connected to the bottom starting end of the double helix structure 1.3; the bottom starting end of the double helix heater 1 of the double helix structure 1.3 is respectively provided with an electrode bolt reserved hole 1.1, and the electrode bolt reserved hole 1.1 is sleeved with the graphite electrode 3.

[0029] The main heater 2 is attached to the inner wall of the cylindrical box 7 in a surrounding manner, and the main heater 2 is installed above the double-helix heater 1 .

[0030] The support rod 5 is vertically mounted on the central axis of the cylindrical box 7, and passes through the crucible 6 and the double-helix heater 1. A circular support rod hole 1.2 is provided in the middle of the circular platform 1.4 on the upper part of the double-helix structure 1.3, and the support rod hole 1.2 is sleeved with the support rod 5.

[0031] The bottom insulation 4 is fixed on the inner bottom surface of the cylindrical box 7, and the graphite electrode 3 is fixed on the upper part of the bottom insulation 4.

[0032] Example 2

[0033] The utility model provides a single crystal furnace thermal field with a double spiral heater, such as Figures 2 to 4 As shown. The thermal field of the single crystal furnace is a cylindrical box 7 with an internal cavity, which accommodates the crucible to be placed vertically and taken out, and also includes: a double helix heater 1 arranged at the bottom of the crucible 6, the double helix heater 1 is a three-dimensional double helix structure 1.3, the double helix structure 1.3 is composed of two groups of heating tubes that spiral from bottom to top in a decreasing rotation radius, and the upper part of the double helix structure 1.3 is connected to a circular platform 1.4, and the lower starting end of the double helix structure 1.3 and the extension line of the upper circular platform 1.4 intersect with the central axis of the double helix heater 1 to form a cone angle α; the size of the cone angle α depends on the lower radius of the double helix structure 1.3, the radius of the upper circular platform 1.4, and the height of the double helix heater 1. In this embodiment, it is assumed that the cross-sectional section of the heating zone of the double helix heater 1 is: b; the pitch height is: h; arctan (b / 2h) < α < arctan (3b / 2h). Within this angle range, it can be ensured that the effective area of ​​the upper and lower heating areas of the top view will not shrink or expand excessively, thereby avoiding heat loss. Since the present invention is a three-dimensional space, it causes axial heating at each level under the same power, and both the rate of temperature increase and the thermal insulation performance are better than other plane types. Secondly, according to the thermal radiation equation P∝T^4 / d^2; where P is the thermal radiation power, T is the thermal radiation temperature, and d is the distance between the thermal radiator and the receiver, it can be seen from the relationship that when T is consistent, the smaller d is, the larger P is. The distance h1 between the circular platform 1.4 and the crucible 6 of the present invention just shortens the plane thermal radiation distance H1, increases the bottom thermal radiation power, ensures the stability of the bottom temperature, and eliminates the temperature gradient caused by the excessively high temperature at the edge of the crucible 6.

[0034] The graphite electrode 3 includes two groups, which are respectively connected to the bottom starting end of the double helix structure 1.3; the bottom starting end of the double helix heater 1 of the double helix structure 1.3 is respectively provided with an electrode bolt reserved hole 1.1, and the electrode bolt reserved hole 1.1 is sleeved with the graphite electrode 3.

[0035] The main heater 2 is attached to the inner wall of the cylindrical box 7 in a surrounding manner, and the main heater 2 is installed above the double-helix heater 1 .

[0036] The support rod 5 is vertically mounted on the central axis of the cylindrical box 7, and passes through the crucible 6 and the double-helix heater 1. A circular support rod hole 1.2 is provided in the middle of the circular platform 1.4 on the upper part of the double-helix structure 1.3, and the support rod hole 1.2 is sleeved with the support rod 5.

[0037] The bottom insulation 4 is fixed on the inner bottom surface of the cylindrical box 7, and the graphite electrode 3 is fixed on the upper part of the bottom insulation 4.

[0038] A cylindrical box 7, a single crystal furnace thermal field with a double spiral heater provided in the present disclosure is carried out in a cylindrical box 7. The design of the box can realize the situation where the main heater 2 on the side and the double spiral heater 1 at the bottom are heated together, thereby solving the problem of uneven temperature and low thermal efficiency in the crucible 6 caused by bottom heating only.

[0039] In order to overcome the problem of temperature gradient in the crucible 6, the present disclosure also provides a double-helix heater 1 with a three-dimensional double-helix structure 1.3, with the heating area decreasing from bottom to top, and forming a hierarchically differentiated heat radiation space based on different distances from the crucible 6 in the axial direction, thereby solving the problem of temperature gradient caused by the prior art, that is, the problem of "temperature increasing from the center to the edge" at the bottom of the crucible 6. In addition, the three-dimensional double-helix structure 1.3, due to the presence of the side, can bring a larger heating area and achieve higher thermal efficiency.

[0040] The heat generation of the existing planar bottom heater is affected by the space and structure. Providing continuous and uniform heat radiation will cause high-temperature baking of the bottom graphite felt. In the technical solution disclosed in the present invention, the bottom double-helix heater 1 is at a distance of (H1-h1) relative to the bottom graphite felt, which can prevent the graphite felt from entering the aging period prematurely.

[0041] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A single crystal furnace thermal field with a double spiral heater, characterized in that: The single crystal furnace thermal field is a cylindrical box with an internal cavity, which accommodates the vertical placement and removal of the crucible, and also includes: A double-helix heater is arranged at the bottom of the crucible, and the double-helix heater is a three-dimensional double-helix structure. The double-helix structure is composed of two groups of heating tubes spiraling from bottom to top in a decreasing rotation radius. The upper part of the double-helix structure is connected to a circular platform, and the lower starting end of the double-helix structure and the extension line of the upper circular platform intersect with the central axis of the heater to form a cone angle; A graphite electrode, wherein the graphite electrode comprises two groups, each of which is connected to the bottom starting end of the double helix structure; A main heater is attached to the inner wall of the cylindrical box in a surrounding manner, and the main heater is installed above the heater; A supporting rod is vertically mounted on the central axis of the cylindrical box, and the supporting rod passes through the crucible and the heater.

2. A single crystal furnace thermal field with a double spiral heater according to claim 1, characterized in that: It also includes bottom insulation, which is fixed on the inner bottom surface of the cylindrical box, and the graphite electrode is fixed on the upper part of the bottom insulation.

3. The single crystal furnace thermal field with a double spiral heater according to claim 1, characterized in that: An electrode bolt reserved hole is respectively provided at the bottom starting end of the double-helix structure heater, and the electrode bolt reserved hole is sleeved with the graphite electrode.

4. The single crystal furnace thermal field with a double spiral heater according to claim 1, characterized in that: A circular supporting rod hole is provided in the middle of the circular platform on the upper part of the double helix structure, and the supporting rod is sleeved in the supporting rod hole.

5. The single crystal furnace thermal field with a double spiral heater according to claim 1, characterized in that: The size of the cone angle depends on the lower radius of the double helix structure, the radius of the upper circular platform, and the height of the heater.

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