Stepped main heater for single crystal furnace

Abstract

A stepped main heater for a single crystal furnace comprises a plurality of heating assemblies distributed in the circumferential direction of the single crystal furnace, gaps exist between the adjacent heating assemblies, a heating space is defined by all the heating assemblies, and each heating assembly comprises an upper heating plate and a lower heating plate which are distributed up and down. The upper heating plate and the lower heating plate are fixedly connected through at least one transition heating plate, all the transition heating plates surround to form a transition heating area, the space of the transition heating area is gradually reduced from top to bottom to form a stepped transition heating area, and the structure can be far away from a solid-liquid interface, so that the temperature gradient is more linear. Part of two adjacent lower heating plates are fixedly connected through a bottom heating plate, and the bottom heating plate extends towards the heating space. The temperature of the bottom of the molten silicon is improved, so that the temperature difference between the upper part and the lower part of the molten silicon can be improved, the temperature gradient in the whole molten silicon is remarkably improved, and the crystal defect caused by insufficient temperature gradient in the drawing process is reduced.

Description

Technical Field

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

[0002] In the semiconductor manufacturing field, the production of silicon single crystal rods is moving towards larger sizes and higher quality. In this process, precise control of the temperature gradient has become one of the key factors affecting the quality of silicon single crystal rods, especially during the heavily doped pulling process.

[0003] Common crystal defects include native particles (COPs), channeling defects, dislocations, impurities, and grain boundaries. Native particles (COPs) and channeling defects can lead to uneven electric field distribution within the device, increasing the risk of leakage current and affecting the device's breakdown voltage and long-term reliability. Dislocations and impurities can act as scattering centers for charge carriers, reducing the device's carrier mobility and thus affecting its conductivity and switching speed. Grain boundaries, as discontinuous interfaces in the crystal structure, can induce current concentration effects, leading to localized overheating and even failure. Therefore, effective control of crystal defects is crucial for ensuring the parameter stability, voltage control accuracy, and reduction of leakage current in subsequent semiconductor devices.

[0004] Temperature gradients play a crucial role in crystal growth, directly influencing growth rate, structural integrity, and the formation and distribution of defects. In the pulling process of silicon single crystal rods, optimizing the temperature gradient can control the thermodynamic conditions at the melt-solid interface, thereby affecting crystal growth kinetics and reducing crystal defects. A suitable temperature gradient promotes the formation of a uniform and ordered crystal structure, reduces defect density, and improves crystal quality.

[0005] Existing technologies primarily control the temperature gradient by adjusting the location of the crystallization interface and the thickness of the insulation layer. However, these methods still have limitations and do not solve the problem of crystal defects caused by insufficient temperature gradient. Utility Model Content

[0006] To address the problem of crystal defects caused by insufficient temperature gradient in existing technologies, this invention provides a stepped main heater for single crystal furnaces, which reduces crystal defects.

[0007] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: a stepped main heater for a single crystal furnace, comprising multiple heating components distributed along the circumference of the single crystal furnace, with gaps between adjacent heating components, and all heating components enclosing a heating space. The heating components include an upper heating plate and a lower heating plate distributed vertically, and the upper heating plate and the lower heating plate are fixedly connected by at least one transition heating plate. All transition heating plates surround to form a transition heating zone, and the space of the transition heating zone gradually decreases from top to bottom. Some adjacent lower heating plates are fixedly connected by a bottom heating plate, and the bottom heating plate extends toward the heating space.

[0008] As a further optimization of the stepped main heater for a single crystal furnace according to the utility model: the transition heating plate includes a first heating plate, a second heating plate and a third heating plate arranged and fixedly connected from top to bottom, the first heating plate in the uppermost transition heating plate is fixedly connected to the upper heating plate, and the third heating plate in the lowermost transition heating plate is fixedly connected to the lower heating plate.

[0009] As a further optimization of the stepped main heater for a single crystal furnace according to the utility model: an upper heat dissipation channel is provided on the upper heating plate, a transition heat dissipation channel is provided on the transition heating plate, and a lower heat dissipation channel is provided on the lower heating plate. The upper heat dissipation channel and the lower heat dissipation channel are connected through the transition heat dissipation channel.

[0010] As a further optimization of the stepped main heater for a single crystal furnace according to the utility model: the transition heat dissipation channel includes a first heat dissipation channel opened on the first heating plate, a second heat dissipation channel opened on the second heating plate, and a third heat dissipation channel opened on the third heating plate, wherein the first heat dissipation channel, the second heat dissipation channel and the third heat dissipation channel are connected.

[0011] As a further optimization of the stepped main heater for a single crystal furnace according to the utility model: the width of the first heat dissipation channel gradually decreases from top to bottom.

[0012] As a further optimization of the stepped main heater for a single crystal furnace, the bottom heating plate is provided with a bottom heat dissipation channel that communicates with the lower heat dissipation channel. The bottom heat dissipation channel extends toward the heating space. Two connecting parts are formed on both sides of the bottom heating plate, and the two connecting parts are fixedly connected to the adjacent lower heating plate.

[0013] As a further optimization of the stepped main heater for a single crystal furnace according to the utility model: part of the lower heating plate is fixedly connected to the connector in the single crystal furnace through a connecting plate.

[0014] As a further optimization of the stepped main heater for a single crystal furnace according to the utility model: the width of the bottom heating plate gradually decreases along the direction toward the heating space.

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

[0016] 1) This utility model sets up an upper heating plate and a lower heating plate distributed vertically. The upper heating plate and the lower heating plate are fixedly connected by at least one transition heating plate. All the transition heating plates surround to form a transition heating zone. The space of the transition heating zone gradually decreases from top to bottom to form a stepped transition heating zone. This structure can move away from the solid-liquid interface, making the temperature gradient more linear. At the same time, because the upper heating plate is farther away from the center of the molten silicon interface than the lower heating plate, the longitudinal temperature gradient of the solid-liquid interface can be significantly improved.

[0017] 2) By setting a bottom heating plate, the two adjacent bottom heating plates are fixedly connected by the bottom heating plate. The bottom heating plate extends toward the heating space, which increases the temperature at the bottom of the molten silicon. This increases the temperature difference between the top and bottom of the molten silicon, thereby significantly increasing the temperature gradient in the overall molten silicon and reducing crystal defects caused by insufficient temperature gradient during the pulling process. Attached Figure Description

[0018] Figure 1 This is the front view of this utility model;

[0019] Figure 2 This is a partial enlarged view of section A of this utility model;

[0020] Figure 3 This is a perspective view of the present invention;

[0021] Figure 4 This is a schematic diagram showing the connection between the bottom heating plate and the lower heating plate of this utility model;

[0022] Figure 5 This is a top view of the present invention;

[0023] The diagram shows the following markings: 1. Upper heating plate; 101. Upper heat dissipation channel; 102. Upper heating zone; 2. Transition heating plate; 201. First heating plate; 2011. First heat dissipation channel; 2012. First heating zone; 202. Second heating plate; 2021. Second heat dissipation channel; 2022. Second heating zone; 203. Third heating plate; 2031. Third heat dissipation channel; 2032. Third heating zone; 3. Lower heating plate; 301. Lower heat dissipation channel; 302. Lower heating zone; 4. Bottom heating plate; 401. Bottom heat dissipation channel; 402. Connecting part; 5. Connecting plate; 6. Heating space. Detailed Implementation

[0024] 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 materials of the upper heating plate 1, the lower heating plate 3, the transition heating plate 2 and the bottom heating plate 4.

[0025] A stepped main heater for a single crystal furnace, such as Figures 1-5 As shown, the invention includes multiple heating components distributed along the circumference of the single crystal furnace. There are gaps between adjacent heating components to facilitate heat dissipation, and all heating components enclose a heating space 6. The heating components include an upper heating plate 1 and a lower heating plate 3 distributed vertically. The overall height of the main heater of this invention remains constant relative to the height of the thermal field. The upper heating plate 1 and the lower heating plate 3 are fixedly connected by at least one transition heating plate 2. All transition heating plates 2 surround to form a transition heating zone, and the transition heating zone gradually shrinks from top to bottom to form a stepped transition heating zone. This structure can move away from the solid-liquid interface, making the temperature gradient more linear.

[0026] The transition heating plate 2 includes a first heating plate 201, a second heating plate 202, and a third heating plate 203, which are arranged sequentially from top to bottom and fixedly connected. The first heating plate 201, the second heating plate 202, and the third heating plate 203 have different thicknesses, resulting in different resistivities, thus altering the heat generation and further adjusting the temperature gradient. The first heating plate 201 in the uppermost transition heating plate 2 is fixedly connected to the upper heating plate 1, and the third heating plate 203 in the lowermost transition heating plate 2 is fixedly connected to the lower heating plate 3. Figure 2 As shown, all the upper heating plates 1 of this utility model surround to form an upper heating area 102, which is annular; all the first heating plates 201 surround to form a first heating area 2012, which is a conical shape with a gradually decreasing radius from top to bottom; all the second heating plates 202 surround to form a second heating area 2022, which is annular; all the third heating plates 203 surround to form a third heating area 2032, which is a conical shape with a gradually decreasing radius from top to bottom; the first heating area 2012, the second heating area 2022, and the third heating area 2032 together form the transition heating area, and all the lower heating plates 3 form a lower heating area 302.

[0027] The transition heating zone, upper heating zone 102, and lower heating zone 302 together form the heating space 6. Conventional heaters are vertically oriented, but in this invention, each heating zone from top to bottom is smaller than the previous one, altering the amount of heat radiated to the molten silicon interface. The further away, the less heat is radiated. This adjustment provides a wider range of adjustment for the heat preservation gradient compared to previous methods, and also increases the distance between the upper heating plate 1 and the transition heating plate 2 and the grain boundary interface. The upper heating plate 1 and the transition heating plate 2 are both slightly thinner than the lower heating plate 3, allowing for precise control of the radiated heat ratio and improving the temperature gradient.

[0028] Two adjacent lower heating plates 3 are fixedly connected by a bottom heating plate 4, which extends toward the heating space 6. The bottom heating plate 4 and the lower heating plate 3 can be designed as a single structure, which increases the temperature at the bottom of the molten silicon, thereby increasing the temperature difference between the top and bottom of the molten silicon and significantly improving the temperature gradient in the overall molten silicon. This reduces crystal defects caused by insufficient temperature gradient during the pulling process, reduces defect productivity at the source, and improves the quality of silicon single crystal rods. The bottom heating plate 4 has a bottom heat dissipation channel 401 that communicates with the lower heat dissipation channel 301. The bottom heat dissipation channel 401 extends toward the heating space 6, and two connecting parts 402 are formed on both sides of the bottom heating plate 4. The two connecting parts 402 are fixedly connected to the adjacent lower heating plates 3. In order not to affect the mutual interference between adjacent bottom heating plates 4, the width of the bottom heating plate 4 gradually decreases along the direction toward the heating space 6. In order to fix the main heater to the single crystal furnace, part of the lower heating plate 3 is fixedly connected to the connector in the single crystal furnace through a connecting plate 5.

[0029] To further reduce the radiation area, an upper heat dissipation channel 101 is provided on the upper heating plate 1, a transition heat dissipation channel is provided on the transition heating plate 2, and a lower heat dissipation channel 301 is provided on the lower heating plate 3. The upper heat dissipation channel 101 and the lower heat dissipation channel 301 are connected through the transition heat dissipation channel. The transition heat dissipation channel includes a first heat dissipation channel 2011 on the first heating plate 201, a second heat dissipation channel 2021 on the second heating plate 202, and a third heat dissipation channel 2031 on the third heating plate 203. The first heat dissipation channel 2011, the second heat dissipation channel 2021, and the third heat dissipation channel 2031 are connected. The first heat dissipation channel 2011 on the uppermost first heating plate 201 is connected to the upper heat dissipation channel 101, and the third heat dissipation channel 2031 on the lowermost third heating plate 203 is connected to the lower heat dissipation channel 301. The width of the first heat dissipation channel 2011 gradually decreases from top to bottom to prevent cracking of the first heat dissipation channel 2011 and extend the service life of the first heating plate 201.

[0030] 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 stepped main heater for a single crystal furnace, comprising a plurality of heating components distributed along the circumference of the single crystal furnace, with gaps between adjacent heating components, and all heating components enclosing a heating space (6), characterized in that: The heating assembly includes an upper heating plate (1) and a lower heating plate (3) distributed vertically. The upper heating plate (1) and the lower heating plate (3) are fixedly connected by at least one transition heating plate (2). All the transition heating plates (2) surround each other to form a transition heating zone, and the space of the transition heating zone gradually decreases from top to bottom. Two adjacent lower heating plates (3) are fixedly connected by a bottom heating plate (4), which extends toward the heating space (6).

2. The stepped main heater for a single crystal furnace as described in claim 1, characterized in that: The transition heating plate (2) includes a first heating plate (201), a second heating plate (202) and a third heating plate (203) arranged and fixedly connected from top to bottom. The first heating plate (201) in the uppermost transition heating plate (2) is fixedly connected to the upper heating plate (1), and the third heating plate (203) in the lowermost transition heating plate (2) is fixedly connected to the lower heating plate (3).

3. The stepped main heater for a single crystal furnace as described in claim 2, characterized in that: The upper heating plate (1) has an upper heat dissipation channel (101), the transition heating plate (2) has a transition heat dissipation channel, and the lower heating plate (3) has a lower heat dissipation channel (301). The upper heat dissipation channel (101) and the lower heat dissipation channel (301) are connected through the transition heat dissipation channel.

4. The stepped main heater for a single crystal furnace as described in claim 3, characterized in that: The transition heat dissipation channel includes a first heat dissipation channel (2011) on the first heating plate (201), a second heat dissipation channel (2021) on the second heating plate (202), and a third heat dissipation channel (2031) on the third heating plate (203), and the first heat dissipation channel (2011), the second heat dissipation channel (2021) and the third heat dissipation channel (2031) are connected.

5. The stepped main heater for a single crystal furnace as described in claim 4, characterized in that: The width of the first heat dissipation channel (2011) gradually decreases from top to bottom.

6. The stepped main heater for a single crystal furnace as described in claim 3, characterized in that: The bottom heating plate (4) is provided with a bottom heat dissipation channel (401) that communicates with the bottom heat dissipation channel (301). The bottom heat dissipation channel (401) extends toward the heating space (6). Two connecting parts (402) are formed on both sides of the bottom heating plate (4). The two connecting parts (402) are fixedly connected to the adjacent bottom heating plate (3).

7. The stepped main heater for a single crystal furnace as described in claim 1, characterized in that: The lower heating plate (3) is fixedly connected to the connector in the single crystal furnace via a connecting plate (5).

8. The stepped main heater for a single crystal furnace as described in claim 1, characterized in that: The width of the bottom heating plate (4) gradually decreases along the direction toward the heating space (6).

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