Monocrystalline silicon growth furnace

Abstract

The monocrystalline silicon growth furnace comprises a furnace body, a heat preservation cylinder, a heater, a crucible and a flow guide cylinder, the heat preservation cylinder, the heater, the crucible and the flow guide cylinder are all arranged in the furnace body, the heater is cylindrical, the heat preservation cylinder is located on the radial outer side of the heater, the crucible is located on the inner side of the heater, and the flow guide cylinder comprises a supporting part and a flow guide part which are connected with each other; the flow guide part is located below the supporting part, the supporting part is transversely arranged above the heat preservation barrel and connected with the heat preservation barrel, the flow guide part is located on the inner side of the heat preservation barrel, an airflow channel is formed between the flow guide part and the heat preservation barrel, and the flow guide part comprises a first section connected with the supporting part; the guide inclined surface gradually inclines from top to bottom in the direction away from the heat-insulating cylinder. According to the application, the unsmooth air flow when the crucible moves upwards to the crucible wall between the heat preservation cylinder and the flow guide cylinder is greatly relieved.

Description

Technical Field

[0001] This application relates to the technical field of single-crystal silicon production equipment, and particularly to a single-crystal silicon growth furnace. Background Art

[0002] The single-crystal silicon growth furnace is the main equipment for single-crystal silicon production. The single-crystal silicon growth furnace realizes the stable growth of single-crystal silicon by controlling the temperature and gas flow of the heater, heat preservation cylinder, crucible and deflector cylinder. Single-crystal silicon is widely used in the semiconductor and solar photovoltaic industries, and its quality directly affects the performance and lifespan of end products. During the crystal pulling process, the gas flow is an important carrier for impurity discharge. Dust in the thermal field and oxygen volatilized from the silicon liquid will be discharged from the furnace body along with the gas flow.

[0003] However, in the middle and late stages of crystal pulling of the existing single-crystal silicon growth furnace, the crucible moves upward until the crucible wall is located between the heat preservation cylinder and the deflector cylinder. The crucible wall divides the gas flow channel between the heat preservation cylinder and the deflector cylinder, further exacerbating the problem of poor gas flow. As a result, the gas flow between the heat preservation cylinder and the deflector cylinder is easily accumulated above the crucible and difficult to discharge. Not only are impurities difficult to discharge with the gas flow, but also the silicon oxide volatilized from the silicon liquid cannot be discharged in time, resulting in high oxygen content and a decline in the quality of the crystal bar. At the same time, the graphite dust in the thermal field cannot be discharged with the gas flow, which is likely to cause ignition and serious solidification of silicon vapor, seriously damaging the thermal field. Moreover, poor gas flow will cause the crystal bar to shake or even fall, resulting in serious production safety accidents. In addition, poor gas flow will also increase the power consumption of the vacuum pump and shorten the service life of the pump body. Summary of the Invention

[0004] The purpose of this application is to provide a single-crystal silicon growth furnace to solve the problem of poor gas flow in the middle and late stages of crystal pulling of the existing single-crystal silicon growth furnace.

[0005] To achieve one of the above application purposes, an embodiment of this application provides a single-crystal silicon growth furnace, including a furnace body, a heat preservation cylinder, a heater, a crucible and a deflector cylinder. The heat preservation cylinder, the heater, the crucible and the deflector cylinder are all arranged in the furnace body. The heater is in a cylindrical shape. The heat preservation cylinder is located radially outside the heater. The crucible is located inside the heater. The deflector cylinder includes a support part and a deflector part connected to each other. The deflector part is located below the support part. The support part is horizontally placed above the heat preservation cylinder and connected to the heat preservation cylinder. The deflector part is located inside the heat preservation cylinder and forms a gas flow channel with the heat preservation cylinder. The deflector part includes a first section connected to the support part. The first section has a guiding inclined surface facing the heat preservation cylinder. The guiding inclined surface gradually inclines downward along the direction away from the heat preservation cylinder.

[0006] As a further improvement of an embodiment of the present application, the crucible has a side wall formed around its axis, the side wall is parallel to the axis of the crucible, and the extension plane of the side wall intersects the guiding inclined surface.

[0007] As a further improvement of an embodiment of the present application, the upper end of the guiding inclined surface is connected to the heat preservation cylinder, and the upper end of the guiding inclined surface is connected to the supporting part.

[0008] As a further improvement of an embodiment of the present application, the heat preservation cylinder includes an upper section and a lower section connected to each other, the lower section is located below the upper section, the heater is located below the upper section, and the inner surfaces of the upper section and the lower section are located on the same circumferential surface.

[0009] As a further improvement of an embodiment of the present application, the heat preservation cylinder includes an upper section and a lower section connected to each other, the lower section is located below the upper section, the heater is located below the upper section, and the upper section is located axially outside the lower section.

[0010] As a further improvement of an embodiment of the present application, the heat preservation cylinder includes an upper section and a lower section connected to each other, the lower section is located below the upper section, the heater is located below the upper section, the guiding part further includes a second section located below the first section, the second section has a guiding surface facing the heat preservation cylinder, the guiding surface extends from top to bottom, and the distance R0 along the radial direction of the heat preservation cylinder between the guiding surface and the inner surface of the upper section is ≤ 600 mm.

[0011] As a further improvement of an embodiment of the present application, the distance R1 from the upper section to the axis of the crucible is ≤ 1200 mm.

[0012] As a further improvement of an embodiment of the present application, the distance R2 from the guiding surface to the axis of the crucible is ≤ 800 mm.

[0013] As a further improvement of an embodiment of the present application, the guiding part further includes a second section and a third section connected in sequence from top to bottom, the second section is connected to the lower end of the first section, and one side surface of the third section facing the heat preservation cylinder gradually inclines downward along the direction away from the heat preservation cylinder.

[0014] As a further improvement of an embodiment of the present application, one side surface of the guiding part facing away from the heat preservation cylinder includes an inclined surface, the lower end of the inclined surface is connected to the lower end of one side surface of the third section facing the heat preservation cylinder, and the inclined surface gradually inclines downward along the direction away from the heat preservation cylinder.

[0015] Compared with the prior art, for the single-crystal silicon growth furnace of the present application, by optimizing the structural design of the heat preservation cylinder and the flow guide cylinder, on the one hand, the heat preservation cylinder is located radially outside the heater, so that the air flow between the heater and the heat preservation cylinder can avoid being blocked by the heat preservation cylinder during the upward flow process, thus avoiding poor air flow. On the other hand, the width of the air flow channel can be increased, so that there is enough space between the heat preservation cylinder and the flow guide cylinder for the air flow to flow. Further, through the setting of the guiding inclined surface of the guiding part in the flow guide cylinder, the air flow in the air flow channel can flow more smoothly, enabling the air flow to be discharged as soon as possible and avoiding accumulation above the crucible, greatly alleviating the poor air flow when the crucible moves upward to the crucible wall between the heat preservation cylinder and the flow guide cylinder in the middle and late stages of crystal pulling, ensuring the smooth air flow above the silicon liquid surface in the crucible, eliminating the eddy current, avoiding the crystal bar shaking caused by poor air flow, facilitating the timely discharge of silicon oxide, graphite dust, etc. in the thermal field, greatly reducing the risk of arc ignition in the thermal field, improving the cleanliness of the crystal growth environment, reducing the power consumption of the vacuum pump, and prolonging the service life of the pump body. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic cross-sectional structure diagram of a single-crystal silicon growth furnace according to an embodiment of the present application;

[0017] Figure 2 is this Figure 1 magnified schematic diagram of part A therein;

[0018] Figure 3 is a schematic cross-sectional structure diagram of a single-crystal silicon growth furnace according to another embodiment of the present application;

[0019] Figure 4 is this Figure 3 magnified schematic diagram of part B therein;

[0020] Figure 5 is Figure 3 simulation effect diagram of the air flow distribution of the single-crystal silicon growth furnace shown.

[0021] DESCRIPTION OF THE REFERENCE NUMERALS:

[0022] 100, single-crystal silicon growth furnace; 1, furnace body; 2, heat preservation cylinder; 21, upper section; 22, lower section; 3, heater; 4, crucible; 41, axis; 42, side wall; 5, flow guide cylinder; 51, support part; 52, guiding part; 521, first section; 5211, guiding inclined surface; 522, second section; 5221, guiding surface; 523, third section; 524, inclined surface; 525, vertical surface; 6, air flow channel. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The present application will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings.

[0024] In the various diagrams of the present application, for the convenience of illustration, the dimensions of certain structures or parts are enlarged relative to other structures or parts. Therefore, it is only used to illustrate the basic structure of the subject matter of the present application.

[0025] It should be understood that although the terms "first", "second", "third", etc. may be used in this document to describe various elements, structures or parameters, the objects described should not be limited by these terms. These terms are only used to distinguish these described objects from each other.

[0026] Refer Figures 1 to 4 As shown, an embodiment of the present application provides a single crystal silicon growth furnace 100, including a furnace body 1, a heat preservation cylinder 2, a heater 3, a crucible 4 and a flow guiding cylinder 5.

[0027] Among them, the heat preservation cylinder 2, the heater 3, the crucible 4 and the flow guiding cylinder 5 are all arranged in the furnace body 1. The heater 3 is in a cylindrical shape. The heat preservation cylinder 2 is located radially outside the heater 3, and the crucible 4 is located inside the heater 3.

[0028] The flow guiding cylinder 5 includes a supporting part 51 and a flow guiding part 52 connected to each other. The flow guiding part 52 is located below the supporting part 51. The supporting part 51 is horizontally placed above the heat preservation cylinder 2 and connected to the heat preservation cylinder 2. The flow guiding part 52 is located inside the heat preservation cylinder 2 and forms an air flow channel 6 with the heat preservation cylinder 2. The flow guiding part 52 includes a first section 521 connected to the supporting part 51. The first section 521 has a guiding inclined surface 5211 facing the heat preservation cylinder 2, and the guiding inclined surface 5211 gradually inclines downward along the direction away from the heat preservation cylinder 2.

[0029] By optimizing the structural design of the draft tube 5 and the heat preservation cylinder 2, on the one hand, the heat preservation cylinder 2 is located radially outside the heater 3, so that the air flow between the heater 3 and the heat preservation cylinder 2 can avoid being blocked by the heat preservation cylinder 2 during the upward flow, thus avoiding poor air flow. On the other hand, the width of the air flow channel 6 can be increased, so that there is enough space between the heat preservation cylinder 2 and the draft tube 5 for air flow. Further, through the setting of the guiding inclined surface 5211 of the guiding part 52 in the draft tube 5, the air flow in the air flow channel 6 can flow more smoothly, so that the air flow can be discharged as soon as possible and avoid accumulating above the crucible 4, greatly alleviating the poor air flow when the crucible 4 moves upward in the middle and late stages of crystal pulling until the wall of the crucible 4 is located between the heat preservation cylinder 2 and the draft tube 5, ensuring the smooth air flow above the silicon liquid level in the crucible 4, eliminating the eddy current, avoiding the crystal rod shaking caused by poor air flow, being conducive to timely discharging silicon oxide, graphite dust, etc. in the thermal field, greatly reducing the risk of arc ignition in the thermal field, improving the cleanliness of the crystal growth environment, reducing the power consumption of the vacuum pump, and prolonging the service life of the pump body.

[0030] The crucible 4 has a side wall 42 formed around its axis 41, the side wall 42 is parallel to the axis 41 of the crucible 4, and the extension surface of the side wall 42 intersects with the guiding inclined surface 5211. In this way, the air flow outside the crucible 4 will always encounter the guiding inclined surface 5211 when moving upward, so that it can flow downward along the guiding inclined surface 5211 into the space above the silicon liquid level in the crucible 4 under the guiding action of the guiding inclined surface 5211, and then be discharged from the furnace body 1.

[0031] Wherein, the distance d between the upper end of the guiding inclined surface 5211 and the heat preservation cylinder 2 is d≥0.

[0032] See Figures 1 to 2 , in an embodiment, the upper end of the guiding inclined surface 5211 is connected to the heat preservation cylinder 2, that is, the distance d between the upper end of the guiding inclined surface 5211 and the heat preservation cylinder 2 is d = 0. In this way, when the air flow flows in the air flow channel 6, when the air flow reaches the top of the air flow channel 6, it is directly guided by the guiding inclined surface 5211 and flows along the guiding inclined surface 5211 towards the silicon liquid level in the crucible 4, improving the smoothness of the air flow and avoiding the accumulation of air flow at the top of the air flow channel 6.

[0033] More preferably, the upper end of the guiding inclined surface 5211 is simultaneously connected to both the heat preservation cylinder 2 and the supporting portion 51, that is, the upper end of the guiding inclined surface 5211 is connected to both the supporting portion 51 and the heat preservation cylinder 2. This can ensure that the air flow channel 6 has sufficient height, and avoid the situation that the gap between the side wall 42 of the crucible 4 and the guiding inclined surface 5211 is too small when the crucible 4 moves between the heat preservation cylinder 2 and the flow guiding cylinder 5, resulting in poor air flow.

[0034] See Figures 3 to 4 , in another embodiment, a certain distance can also be set between the upper end of the guiding inclined surface 5211 and the heat preservation cylinder 2, that is, the distance d between the upper end of the guiding inclined surface 5211 and the heat preservation cylinder 2 is greater than 0.

[0035] See Figure 1 and Figure 3 , in one embodiment, the heat preservation cylinder 2 includes an upper section 21 and a lower section 22 which are connected to each other. The lower section 22 is located below the upper section 21. The heater 3 is located below the upper section 21, and the inner surfaces of the upper section 21 and the lower section 22 are located on the same circumferential surface. Here, both the upper section 21 and the lower section 22 are in a cylindrical shape, and the inner surfaces of the upper section 21 and the lower section 22 are located on the same circumferential surface. That is to say, the inner diameter of the upper section 21 is the same as that of the lower section 22, and the central axes of the upper section 21 and the lower section 22 are collinear.

[0036] In this way, it can be avoided that the air flow outside the heater 3 is blocked by the upper section 21 when flowing upward, resulting in poor air flow.

[0037] In another embodiment, the upper section 21 can also be arranged on the circumferential outer side of the lower section 22, which can further increase the space between the upper section 21 and the flow guiding cylinder 5, thereby improving the air flow smoothness.

[0038] See Figure 2 and Figure 4 , the flow guiding portion 52 further includes a second section 522 located below the first section 521. The second section 522 has a flow guiding surface 5221 facing the heat preservation cylinder 2. The flow guiding surface 5221 extends from top to bottom, and the distance R0 along the radial direction of the heat preservation cylinder 2 between the flow guiding surface 5221 and the inner surface of the upper section 21 is less than or equal to 600 mm. Through the setting of this distance range, it can be ensured that the air flow channel 6 has sufficient space, thereby improving the air flow smoothness.

[0039] Among them, the distance R1 from the upper section 21 to the axis 41 of the crucible 4 satisfies R1 ≤ 1200 mm. By controlling the distance from the upper section 21 to the axis 41 of the crucible 4, not only can interference between the moving crucible 4 and the heat preservation cylinder 2 be avoided, but also sufficient space can be ensured between the side wall 42 of the crucible 4 and the heat preservation cylinder 2, so as not to affect the smoothness of the air flow.

[0040] Among them, the distance R2 from the flow guiding surface 5221 to the axis 41 of the crucible 4 satisfies R2 ≤ 800 mm. By controlling the distance from the flow guiding surface 5221 to the axis 41 of the crucible 4, not only can interference between the moving crucible 4 and the flow guiding cylinder 5 be avoided, but also sufficient space can be ensured between the side wall 42 of the crucible 4 and the flow guiding cylinder 5, so as not to affect the smoothness of the air flow.

[0041] Among them, R0 = R1 - R2.

[0042] Furthermore, the flow guiding part 52 further includes a third section 523. The first section 521, the second section 522 and the third section 523 are sequentially connected from top to bottom. That is, the second section 522 is connected to the lower end of the first section 521, the third section 523 is connected to the lower end of the second section 522, and the surface of the third section 523 facing the heat preservation cylinder 2 gradually inclines away from the heat preservation cylinder 2 from top to bottom. In this way, when the air flow is discharged from the air flow channel 6 to above the liquid surface of the silicon liquid in the crucible 4, it can gradually flow towards the central area of the crucible 4 along the surface of the third section 523, thereby improving the smoothness of the air flow and reducing the formation of air flow disorder and eddy current.

[0043] The surface of the flow guiding part 52 facing away from the heat preservation cylinder 2 includes an inclined surface 524. The lower end of the inclined surface 524 is connected to the lower end of the surface of the third section 523 facing the heat preservation cylinder 2, and the inclined surface 524 gradually inclines away from the heat preservation cylinder 2 from top to bottom, so as to optimize the air flow path, prevent air flow disorder and eddy current formation, and improve the smoothness of the air flow.

[0044] The surface of the flow guiding part 52 facing away from the heat preservation cylinder 2 further includes a vertical surface 525. The vertical surface 525 is connected to the inclined surface 524 and the vertical surface 525 is located above the inclined surface 524.

[0045] Pair Figure 3 The air flow distribution of the single crystal silicon growth furnace 100 shown is simulated and analyzed, and the simulation effect diagram is as Figure 5 shown. It can be seen from Figure 5 that there is no air flow dead angle between the flow guiding cylinder 5 and the heat preservation cylinder 2, and the air flow can flow smoothly in the air flow channel 6.

[0046] In summary, for the single-crystal silicon growth furnace 100 of the present application, by optimizing the structural design of the flow guide cylinder 5 and the heat preservation cylinder 2, on the one hand, the heat preservation cylinder 2 is located radially outside the heater 3, so that the air flow between the heater 3 and the heat preservation cylinder 2 can avoid being blocked by the heat preservation cylinder 2 during the upward flow process, thus avoiding poor air flow. On the other hand, the width of the air flow channel 6 can be increased, so that there is enough space between the heat preservation cylinder 2 and the flow guide cylinder 5 for air flow. Further, through the setting of the guiding inclined surface 5211 of the flow guiding portion 52 in the flow guide cylinder 5, the air flow in the air flow channel 6 can flow more smoothly, so that the air flow can be discharged as soon as possible and avoid accumulation above the crucible 4, greatly alleviating the poor air flow when the crucible 4 moves upward in the middle and late stages of crystal pulling until the crucible wall is located between the heat preservation cylinder 2 and the flow guide cylinder 5, ensuring the smooth air flow above the silicon liquid level in the crucible 4, eliminating the eddy current, avoiding the crystal bar shaking caused by poor air flow, being beneficial to timely discharging silicon oxide, graphite dust, etc. in the thermal field, greatly reducing the risk of arc ignition in the thermal field, improving the cleanliness of the crystal growth environment, reducing the power consumption of the vacuum pump, and prolonging the service life of the pump body.

[0047] The structure, characteristics and function effects of the present application have been described in detail based on the embodiments shown in the drawings. The above is only the preferred embodiment of the present application, but the present application is not limited to the implementation scope shown in the drawings. Any changes made according to the concept of the present application, or equivalent embodiments modified into equivalent changes, still within the spirit covered by the specification and the drawings, shall be within the protection scope of the present application.

Claims

1. A single crystal silicon growth furnace, comprising a furnace body, a heat preservation tube, a heater, a crucible and a guide tube, wherein the heat preservation tube, the heater, the crucible and the guide tube are all arranged in the furnace body, characterized in that: The heater is cylindrical, the insulation tube is located on the radially outer side of the heater, the crucible is located on the inner side of the heater, the guide tube includes a support portion and a guide portion connected to each other, the guide portion is located below the support portion, the support portion is horizontally placed above the insulation tube and connected to the insulation tube, the guide portion is located on the inner side of the insulation tube and forms an air flow channel with the insulation tube, the guide portion includes a first section connected to the support portion, the first section has a guiding inclined surface toward the insulation tube, and the guiding inclined surface gradually inclines from top to bottom in a direction away from the insulation tube.

2. The single crystal silicon growth furnace according to claim 1, characterized in that: The crucible has a side wall formed around the axis of the crucible, the side wall is parallel to the axis of the crucible, and an extended surface of the side wall intersects with the guide inclined surface.

3. The single crystal silicon growth furnace according to claim 1, characterized in that: The upper end of the guide slope is connected to the heat preservation tube, and the upper end of the guide slope is connected to the support part.

4. The single crystal silicon growth furnace according to claim 1, characterized in that: The heat preservation cylinder comprises an upper section and a lower section connected to each other, the lower section is located below the upper section, the heater is located below the upper section, and the inner surfaces of the upper section and the lower section are located on the same circumferential surface.

5. The single crystal silicon growth furnace according to claim 1, characterized in that: The heat preservation cylinder comprises an upper section and a lower section connected to each other, the lower section is located below the upper section, the heater is located below the upper section, and the upper section is located axially outside the lower section.

6. The single crystal silicon growth furnace according to claim 1, characterized in that: The insulation tube includes an upper section and a lower section connected to each other, the lower section is located below the upper section, the heater is located below the upper section, the guide portion also includes a second section located below the first section, the second section has a guide surface facing the insulation tube, the guide surface extends from top to bottom, and the radial distance R0 between the guide surface and the inner surface of the upper section along the insulation tube is ≤600mm.

7. The single crystal silicon growth furnace according to claim 6, characterized in that: The distance R1 from the upper section to the axis of the crucible is ≤1200 mm.

8. The single crystal silicon growth furnace according to claim 6, characterized in that: The distance R2 from the guide surface to the axis of the crucible is ≤800 mm.

9. The single crystal silicon growth furnace according to claim 6, characterized in that: The guide portion also includes a second section and a third section connected in sequence from top to bottom, the second section is connected to the lower end of the first section, and the third section gradually inclines from top to bottom in a direction away from the insulation tube on one side surface facing the insulation tube.

10. The single crystal silicon growth furnace according to claim 9, characterized in that: The side surface of the guide portion facing away from the insulation tube includes an inclined surface, the lower end of the inclined surface is connected to the lower end of the side surface of the third section facing the insulation tube, and the inclined surface gradually inclines from top to bottom in a direction away from the insulation tube.

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