Main heater for single crystal furnace

Abstract

A main heater for a single crystal furnace comprises a plurality of first heating components and a plurality of second heating components which are distributed along the circumferential direction of the single crystal furnace, the first heating components and the second heating components form a heating space for heating single crystal silicon, and a gap is reserved between every two adjacent first heating components, so that the radiation area of a quartz crucible is reduced, and the heating efficiency of the single crystal furnace is improved. Therefore, the dissolved quantity of the quartz crucible is reduced, and the oxygen content in the silicon single crystal rod is reduced; the second heating assembly is close to the bottom of the gap, silicon leakage can be prevented, due to the fact that the second heating assembly is additionally arranged close to the bottom of the gap, a temperature gradient is generated, the bottom temperature is high, the upper temperature is relatively low, the crystal pulling speed can be increased, crystal defects are reduced, and due to the fact that the contact area of the first heating assembly and the quartz crucible is greatly reduced, the oxygen content is reduced. And the plurality of first heating assemblies and the plurality of second heating assemblies are arranged, so that the height of the main heater cannot be reduced, and unstable temperature and difficult crystallization caused by strong longitudinal convection of the melt cannot be caused.

Description

Technical Field

[0001] This utility model relates to the field of Czochralski single crystal silicon production technology, specifically a main heater for a single crystal furnace. Background Technology

[0002] With the continuous development of semiconductor technology, the manufacturing of silicon single crystal rods is evolving towards larger sizes, higher quality, and lower costs. However, as the size of silicon single crystal rods continues to increase and the amount of raw materials fed in increases significantly, the problem of high oxygen content and impurities within them is increasingly becoming a key factor restricting product quality. Particularly noteworthy is that, because the segregation coefficient of oxygen is greater than 1, the oxygen content in silicon single crystal rods exhibits a gradually decreasing distribution trend from beginning to end, making it extremely easy for the oxygen content in the head region to exceed the standard range, thus leading to yield losses.

[0003] The primary source of oxygen impurities can be attributed to the dissolution reaction of the quartz crucible at high temperatures. During this process, the interaction between the heater and the quartz crucible is particularly crucial, as the heater is the sole heat source within the single-crystal furnace. Current mainstream hot zone heater designs mainly consist of a main heater and a bottom heater. The bottom heater is primarily activated during the melting stage and remains off during the pulling of the single-crystal silicon rod, thus having a relatively small impact on the rod quality. In contrast, the main heater bears the heavy responsibility of melting the polycrystalline silicon within the quartz crucible, ensuring that the silicon material remains molten during normal crystal pulling.

[0004] Existing main heater designs typically employ multiple heater plates arranged in a barrel-shaped structure to achieve uniform heating of the quartz crucible. However, as the amount of material fed into the hot zone increases, the melting time also lengthens. With the hot zone dimensions remaining constant, the contact area between the molten silicon and the quartz crucible significantly increases. This intensifies the chemical reaction between the molten silicon and the quartz crucible, leading to an increase in oxygen content and negatively impacting the quality of the single-crystal silicon rod. Current low-oxygen heaters consider reducing the heater height. While reducing the heater height does decrease the oxygen content in the molten silicon to some extent, it also intensifies longitudinal convection in the melt, resulting in temperature instability and making crystal formation extremely difficult. Utility Model Content

[0005] To address the problem that existing technologies, by reducing the heating height of the heater, cause strong longitudinal convection of the melt, leading to temperature instability and difficulties in crystal formation, this invention provides a main heater for a single crystal furnace that reduces oxygen content while ensuring crystal formation.

[0006] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: a main heater for a single crystal furnace, including a plurality of first heating components and a plurality of second heating components distributed along the circumference of the single crystal furnace, wherein the first heating components and the second heating components form a heating space for heating single crystal silicon, there is a gap between adjacent first heating components, the second heating components are close to the bottom of the gap, the second heating components include a plurality of Z-shaped second heating plates, a second heat dissipation channel is formed between the two sides of the second heating plates, adjacent second heating plates are fixedly connected by a second connecting plate, and the second heating plate located at the end of the second heating component is fixedly connected to the adjacent first heating component by a mounting plate.

[0007] As a further optimization of the main heater for a single crystal furnace according to the utility model: the connection between the mounting plate and the first heating component is provided with an arc portion.

[0008] As a further optimization of the main heater for a single crystal furnace according to the utility model: the first heating component includes a plurality of U-shaped first heating plates, a first heat dissipation channel is formed between the two sides of the first heating plates, and adjacent first heating plates are fixedly connected by a first connecting plate.

[0009] As a further optimization of the main heater for a single crystal furnace according to the utility model: the bottom of the first connecting plate is configured as an arc shape that bulges towards the bottom of the single crystal furnace.

[0010] As a further optimization of the main heater for a single crystal furnace according to the utility model: the first heating component has a plurality of first through slots along the axial direction of the single crystal furnace, and the plurality of first through slots are distributed around the circumference of the single crystal furnace.

[0011] As a further optimization of the main heater for a single crystal furnace according to the utility model: a fixing plate is fixedly connected to the bottom of the first heating component, and the fixing plate is fixedly connected to the connector in the single crystal furnace.

[0012] As a further optimization of the main heater for a single crystal furnace according to the utility model: the bottom of the second connecting plate is configured as an arc shape that bulges towards the bottom of the single crystal furnace.

[0013] As a further optimization of the main heater for a single crystal furnace according to the utility model: the width of the second heating element is 9-11mm, and the distance from the top of the second heating element to the bottom of the second connecting plate is 30-50mm.

[0014] As a further optimization of the main heater for a single crystal furnace according to the utility model: the height of the first heating component is 499-501mm.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0016] This invention employs multiple first heating components and multiple second heating components distributed along the circumference of a single crystal furnace, forming a heating space for heating single-crystal silicon. Gaps exist between adjacent first heating components. Furthermore, the fewer heating elements in the first heating components compared to traditional methods reduce the radiation area of ​​the quartz crucible, thereby decreasing the amount of silicon dissolved and lowering the oxygen content in the silicon single crystal rod. The second heating components are located near the bottom of the gaps, preventing silicon leakage. The addition of second heating components near the bottom of the gaps creates a temperature gradient—higher at the bottom and relatively lower at the top—which increases the crystal pulling speed and reduces crystal defects. Moreover, by using multiple first and second heating components, the height of the main heater is not reduced, preventing strong longitudinal convection of the melt that could lead to temperature instability and crystal formation difficulties. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model;

[0018] Figure 2 This is the front view of this utility model;

[0019] Figure 3 This is the left view of this utility model;

[0020] The markings in the diagram are: 1. First heating component, 101. First heating element, 102. First heat dissipation channel, 103. First through groove, 2. Second heating component, 201. Second heating element, 202. Second heat dissipation channel, 3. First connecting plate, 4. Fixing plate, 5. Screw hole, 6. Second through groove, 7. Arc portion, 8. Heating space, 9. Second connecting plate, 10. Mounting plate. Detailed Implementation

[0021] The technical solution of this utility model will be further described in detail below with reference to specific embodiments. Parts not described or disclosed in detail in the following embodiments of this utility model should be understood as prior art known or should be known by those skilled in the art, such as the structure of the single crystal furnace, how silicon single crystal rods are made, etc.

[0022] Example 1

[0023] A main heater for a single crystal furnace, such as Figures 1-3As shown, the invention includes multiple first heating components 1 and multiple second heating components 2 distributed along the circumference of the single crystal furnace. The first heating components 1 and the second heating components 2 form a heating space 8 for heating single crystal silicon. There is a gap between adjacent first heating components 1. The height of the first heating components 1 is 499-501 mm, with an optimal height of 500 mm. Two first heating components 1 can be set, and correspondingly, two second heating components 2 can also be set. Without reducing the height of the main heater, the overall height of the main heater of this invention remains unchanged. The main heater of this invention has only two main heating areas, which reduces the radiation area of ​​the quartz crucible, thereby reducing the amount of dissolution in the quartz crucible and reducing the oxygen content in the silicon single crystal rod. The second heating element 2 is located near the bottom of the gap. Placing the second heating element 2 at this position prevents silicon leakage. Because the second heating element 2 is added near the bottom of the gap, the temperature of the quartz crucible's radius (R-angle) is relatively increased, creating a temperature gradient. The bottom temperature is higher, and the upper temperature is relatively lower, which can increase the crystal pulling speed and reduce crystal defects such as COP (Crystal Originated Particulates). Furthermore, by setting multiple first heating elements 1 and multiple second heating elements 2, the height of the main heater is not reduced, thus avoiding strong longitudinal convection of the melt that could lead to temperature instability and crystal formation difficulties. Additionally, the radius (R-angle) of the quartz crucible is a conventional prior art in this field and will not be elaborated upon further here.

[0024] To prevent the bottom temperature of the quartz crucible from becoming too low during crystal pulling, the second heating assembly 2 includes multiple U-shaped second heating elements 201. The width of each second heating element 201 is 9-11 mm, preferably 10 mm. The distance from the top of the second heating element 201 to the bottom of the second connecting plate 9 is 30-50 mm, preferably 40 mm. A second heat dissipation channel 202 is formed between the two sides of each second heating element 201, increasing heat generation while ensuring heat dissipation. Adjacent second heating elements 201 are fixedly connected by the second connecting plate 9, and a second through groove 6 is formed between adjacent second heating elements 201 through the connecting plate, further enhancing heat dissipation. The second heating elements 201 located at the ends of the second heating assembly 2 are fixedly connected to the adjacent first heating assembly 1 by a mounting plate 10.

[0025] The mounting plate 10, the first heating element 101, the first connecting plate 3, the second heating element 201, and the second connecting plate 9 are all made of graphite. Graphite itself acts as a resistive heating element. When a certain current is passed through it, it heats up rapidly and thus achieves the heating effect.

[0026] The above are the basic embodiments of this utility model. Further improvements, optimizations, and limitations can be made based on the above to obtain the following embodiments:

[0027] Example 2

[0028] This embodiment is an improvement on embodiment 1. Its main structure is the same as embodiment 1, but the improvement lies in the fact that an arc-shaped portion 7 is provided at the connection between the mounting plate 10 and the first heating component 1. The arc-shaped portion 7 can prevent the mounting plate 10 from breaking and avoid stress concentration.

[0029] Example 3

[0030] This embodiment is an improvement on Embodiment 1. Its main structure is the same as Embodiment 1, but the improvement lies in the following: the first heating assembly 1 includes several U-shaped first heating elements 101. There are four first heating elements 101, each with the same height. The four first heating elements 101 reduce the radiation area with the quartz crucible, thereby reducing the amount of quartz dissolved and lowering the oxygen content in the silicon crystal rod. A first heat dissipation channel 102 is formed between the two sides of the first heating elements 101, improving the heat dissipation effect. Adjacent first heating elements 101 are fixedly connected by a first connecting plate 3. The bottom of the first connecting plate 3 is designed to bulge towards the bottom of the single crystal furnace in an arc shape to prevent breakage and avoid stress concentration.

[0031] Example 4

[0032] This embodiment is an improvement on embodiment 1. Its main structure is the same as that of embodiment 1. The improvement is that the first heating component 1 has multiple first through slots 103 along the axial direction of the single crystal furnace, and the multiple first through slots 103 are distributed around the circumference of the single crystal furnace. The first through slots 103 can also form heat dissipation channels to improve the heat dissipation effect.

[0033] Example 5

[0034] This embodiment is an improvement on Embodiment 1. Its main structure is the same as Embodiment 1, but the improvement lies in the following: a fixing plate 4 is fixedly connected to the bottom of the first heating component 1. The fixing plate 4 is fixedly connected to the connector in the single crystal furnace, and screw holes 5 are provided on the fixing plate 4. How the fixing plate 4 connects to the connector is conventional prior art in this field and will not be described in detail here.

[0035] Example 6

[0036] This embodiment is an improvement on embodiment 1. Its main structure is the same as that of embodiment 1. The improvement is that the bottom of the second connecting plate 9 is set to be an arc shape that bulges towards the bottom of the single crystal furnace, so as to avoid stress concentration in the second connecting plate 9 and prevent the second connecting plate 9 from breaking.

[0037] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A main heater for a single crystal furnace, characterized in that: The furnace includes multiple first heating components (1) and multiple second heating components (2) distributed along the circumference of the single crystal furnace. The first heating components (1) and the second heating components (2) form a heating space (8) for heating single crystal silicon. There is a gap between adjacent first heating components (1). The second heating components (2) are close to the bottom of the gap. The second heating components (2) include multiple zigzag second heating plates (201). A second heat dissipation channel (202) is formed between the two sides of the second heating plates (201). Adjacent second heating plates (201) are fixedly connected by a second connecting plate (9). The second heating plate (201) located at the end of the second heating component (2) is fixedly connected to the adjacent first heating component (1) by a mounting plate (10).

2. The main heater for a single crystal furnace as described in claim 1, characterized in that: An arc-shaped portion (7) is provided at the connection between the mounting plate (10) and the first heating component (1).

3. The main heater for a single crystal furnace as described in claim 1, characterized in that: The first heating component (1) includes a plurality of U-shaped first heating elements (101), a first heat dissipation channel (102) is formed between the two sides of the first heating elements (101), and adjacent first heating elements (101) are fixedly connected by a first connecting plate (3).

4. The main heater for a single crystal furnace as described in claim 3, characterized in that: The bottom of the first connecting plate (3) is configured to be an arc shape that bulges toward the bottom of the single crystal furnace.

5. The main heater for a single crystal furnace as described in claim 1, characterized in that: The first heating component (1) has a plurality of first through slots (103) along the axial direction of the single crystal furnace, and the plurality of first through slots (103) are distributed around the circumference of the single crystal furnace.

6. The main heater for a single crystal furnace as described in claim 1, characterized in that: The bottom of the first heating component (1) is fixedly connected to a fixing plate (4), and the fixing plate (4) is fixedly connected to the connector in the single crystal furnace.

7. The main heater for a single crystal furnace as described in claim 1, characterized in that: The bottom of the second connecting plate (9) is configured to be an arc shape that bulges toward the bottom of the single crystal furnace.

8. The main heater for a single crystal furnace as described in claim 1, characterized in that: The width of the second heating element (201) is 9-11mm, and the distance from the top of the second heating element (201) to the bottom of the second connecting plate (9) is 30-50mm.

9. The main heater for a single crystal furnace as described in claim 1, characterized in that: The height of the first heating component (1) is 499-501mm.

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