Heat reflecting screen and single crystal furnace applying same

Abstract

A heat reflecting screen comprises a first reflecting ring plate and a plurality of telescopic rods used for supporting the first reflecting ring plate, the telescopic rods are vertically arranged at the bottom of a single crystal furnace, the distance between the first reflecting ring plate and the bottom of the single crystal furnace can be changed in the telescopic process of the telescopic rods, and a plurality of first heat preservation felts are placed on the first reflecting ring plate. The first heat preservation felt is annular and is coaxial with the first reflection annular plate, and a second reflection annular plate coaxial with the first reflection annular plate is placed on the first heat preservation felt located on the uppermost portion. According to the utility model, the distance between the first reflecting ring plate and the bottom of the single crystal furnace can be adjusted according to actual requirements, and meanwhile, the number of the first heat preservation felts can be flexibly adjusted.

Description

Technical Field

[0001] This utility model relates to the field of single crystal furnace technology, specifically a heat reflector and a single crystal furnace using the heat reflector. Background Technology

[0002] The Czochralski method is a traditional method for producing single-crystal silicon. With continuous advancements in industry technology, higher demands are placed on the precision of silicon single-crystal product parameters and defect control. During single-crystal pulling, the temperature distribution of the melt is a critical factor affecting product quality. Besides fine-tuning process parameters, optimizing the thermal field is equally crucial. Typically, thermal field adjustment focuses on regulating the radial temperature gradient of the melt; while adjusting the longitudinal temperature gradient usually employs a bottom heater structure. However, some traditional, older crystal pulling equipment lacks the space to install a bottom heater. Currently, a common improvement for such equipment is adding a heat reflector to the furnace chassis. This heat reflector is typically composed of an insulation layer and highly reflective material. After fabrication, the entire heat reflector is placed at the bottom of the single-crystal furnace. If the height of the heat reflector needs adjustment, a new heat reflector must be fabricated and replaced entirely, thus existing heat reflectors lack sufficient flexibility for adjustment. Utility Model Content

[0003] To address the problem of insufficient adjustment flexibility in existing heat reflective screens, this invention provides a heat reflective screen and a single-crystal furnace using the heat reflective screen, thereby improving the adjustment flexibility of the heat reflective screen.

[0004] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: a heat reflective screen, including a first reflective ring plate and a plurality of telescopic rods for supporting the first reflective ring plate, wherein the telescopic rods are vertically arranged at the bottom of the single crystal furnace, and the distance between the first reflective ring plate and the bottom of the single crystal furnace can be changed during the extension and retraction of the telescopic rods. A plurality of first heat-insulating felts are placed on the first reflective ring plate, the first heat-insulating felts are annular and coaxial with the first reflective ring plate, and a second reflective ring plate coaxial with the first reflective ring plate is placed on the uppermost first heat-insulating felt.

[0005] As a further optimization of the aforementioned heat reflective screen: the bottom of the first reflective ring plate is provided with multiple grooves that correspond one-to-one with the telescopic rod.

[0006] As a further optimization of the aforementioned heat reflector: the telescopic rod includes an adjusting screw and adjusting nuts that cooperate with the adjusting screw. The adjusting screw is vertically set at the bottom of the single crystal furnace, and the adjusting nuts are correspondingly abutted against the bottom of the groove.

[0007] As a further optimization of the aforementioned heat reflector, an indicator groove is provided on the end face of the adjusting nut that contacts the bottom of the groove.

[0008] As a further optimization of the aforementioned heat reflective screen: the outer edges of the first reflective ring plate and the second reflective ring plate are provided with multiple channels, and the channels correspond one-to-one with the electrodes inside the single crystal furnace.

[0009] As a further optimization of the above-mentioned heat reflector: the inner hole of the second reflector ring plate is fixedly connected to a downwardly extending central cylinder, the first heat insulation felt and the first reflector ring plate are both sleeved on the central cylinder, and the first heat insulation felt is in contact with the outer wall of the central cylinder.

[0010] A single crystal furnace includes a furnace body, an insulation base set at the bottom of the furnace body, and the aforementioned heat reflector. The insulation base includes a chassis and a sleeve fixedly fitted around the periphery of the chassis, with the sleeve extending upward. The lower surface of the chassis has an installation ring groove coaxial with the first reflector ring plate, and a fixed graphite ring is set in the installation ring groove. The adjusting screw passes through the chassis and is screwed to the fixed graphite ring.

[0011] As a further optimization of the aforementioned single crystal furnace: two symmetrical exhaust holes are provided on the side wall of the sleeve, and several notches are provided at the end of the sleeve.

[0012] As a further optimization of the aforementioned single crystal furnace: the heat preservation base is provided with a receiving groove for accommodating multiple second heat preservation felts. Multiple reserved blocks are left at the edge of the receiving groove. The reserved blocks are provided with electrode holes that correspond one-to-one with the electrodes inside the single crystal furnace, and the electrode holes penetrate the heat preservation base.

[0013] As a further optimization of the aforementioned single crystal furnace, a graphite cover plate for sealing the receiving tank is provided in the receiving tank.

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0015] This invention features a first reflective ring plate and several telescopic rods supporting it. The telescopic rods are vertically positioned at the bottom of the single crystal furnace, and their extension and retraction alter the distance between the first reflective ring plate and the bottom of the furnace. Several first insulating felts are placed on the first reflective ring plate, each felt being annular and coaxial with the first reflective ring plate. A second reflective ring plate, coaxial with the first reflective ring plate, is placed on the uppermost insulating felt. This invention allows for adjustment of the distance between the first reflective ring plate and the bottom of the single crystal furnace according to actual needs, and the number of first insulating felts can also be flexibly adjusted. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model;

[0017] Figure 2 This is a schematic diagram of the first reflective ring plate;

[0018] Figure 3 This is a schematic diagram of the adjusting nut;

[0019] Figure 4 This is a schematic diagram of a fixed graphite ring;

[0020] Figure 5 This is a schematic diagram of the heat preservation base;

[0021] Figure 6 This is a schematic diagram of the chassis and sleeve;

[0022] The markings in the diagram are: 1. First reflective ring plate, 2. First insulation felt, 3. Adjusting screw, 4. Adjusting nut, 5. Second reflective ring plate, 6. Channel, 7. Furnace body, 8. Indicator groove, 9. Groove, 10. Central cylinder, 11. Insulation base, 12. Electrode hole, 13. Fixed graphite ring, 14. Graphite cover plate, 15. Second insulation felt, 16. Receiving groove, 17. Exhaust hole, 18. Notch, 19. Chassis, 20. Sleeve, 21. Reserved block. Detailed Implementation

[0023] 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.

[0024] A type of heat-reflective screen, such as Figure 1 and Figure 2 As shown, it includes a first reflective ring plate 1 and several telescopic rods for supporting the first reflective ring plate 1. The telescopic rods are vertically arranged at the bottom of the single crystal furnace. During the extension and retraction of the telescopic rods, the distance between the first reflective ring plate 1 and the bottom of the single crystal furnace can be changed. Several first heat-insulating felts 2 are placed on the first reflective ring plate 1. The first heat-insulating felts 2 are annular and coaxial with the first reflective ring plate 1. A second reflective ring plate 5, coaxial with the first reflective ring plate 1, is placed on the uppermost first heat-insulating felt 2.

[0025] By extending and retracting all the telescopic rods to the same height, the stability of the first reflective ring plate 1 is ensured even when the distance between it and the bottom of the single crystal furnace changes. Since the telescopic rods support the first reflective ring plate 1, when the overall thickness of the first insulation felt 2 needs to be changed, the number of first insulation felts 2 can be increased or decreased accordingly, and then the second reflective ring plate 5 is placed on top of the first insulation felt 2. The inner holes of the first reflective ring plate 1, the second reflective ring plate 5, and the first insulation felt 2 form a channel 6 for the graphite shaft of the single crystal furnace to pass through. The graphite shaft is a conventional technology in this field and will not be described in detail here. Both the first reflective ring plate 1 and the second reflective ring plate 5 are made of graphite. The first insulation felt 2 is preferably a soft felt, which is also a conventional technology in this field and will not be described in detail here.

[0026] The bottom of the first reflective ring plate 1 has multiple grooves 9 corresponding to the telescopic rods, with four grooves 9 in total. The top of the telescopic rod enters the groove 9, which allows the telescopic rod to support the first reflective ring plate 1 while preventing the first reflective ring plate 1 from shifting its position. At the same time, it also ensures that the first reflective ring plate 1 is placed on the telescopic rod in the predetermined position without interfering with the installation of other components in the single crystal furnace.

[0027] like Figure 1 and Figure 3 As shown, the telescopic rod includes an adjusting screw 3 and adjusting nuts 4 that cooperate with the adjusting screw 3. The adjusting screw 3 is vertically set at the bottom of the single crystal furnace, and the adjusting nuts 4 are correspondingly abutted against the bottom of the groove 9. There are four adjusting screws 3. To adjust the distance between the first reflective ring plate 1 and the bottom of the single crystal furnace, the adjusting nuts 4 can be turned to move along the length of the adjusting screw 3, thus changing the distance between the first reflective ring plate 1 and the bottom of the single crystal furnace. Similarly, to adjust the number of first insulation felts 2, the adjusting nuts 4 can be turned to move along the length of the adjusting screw 3, thus changing the distance between the first reflective ring plate 1 and the bottom of the single crystal furnace. Furthermore, increasing the number of first insulation felts 2 increases the distance between the first reflective ring plate 1 and the second reflective ring plate 5; decreasing the number of first insulation felts 2 decreases the distance between the first reflective ring plate 1 and the second reflective ring plate 5.

[0028] An indicator groove 8 is provided on the end face of the adjusting nut 4 that contacts the bottom of the groove 9. The indicator groove 8 is V-shaped, and during machining, the starting point of the thread is required to be at the center of the V-shaped indicator groove 8 to ensure the consistency of thread machining and to lay the foundation for subsequent height adjustment. When the angle of all V-shaped indicator grooves 8 is consistent, it indicates that the height of all adjusting nuts 4 is consistent. Multiple channels 6 are provided on the outer edges of the first reflective ring plate 1 and the second reflective ring plate 5, and the channels 6 correspond one-to-one with the electrodes inside the single crystal furnace, without interfering with the installation of the electrodes. The electrodes are conventional existing technology in this field and will not be described in detail here. A downwardly extending central cylinder 10 is fixedly connected to the inner hole of the second reflective ring plate 5. The first insulation felt 2 and the first reflective ring plate 1 are both sleeved on the central cylinder 10, and the first insulation felt 2 is in contact with the outer wall of the central cylinder 10. The central cylinder 10 is designed to prevent the first insulation felt 2 and the first reflective ring plate 1 from shifting.

[0029] like Figure 1 , Figure 4 , Figure 5 and Figure 6 As shown, the single crystal furnace includes a furnace body 7, a heat-insulating base 11 located at the bottom of the furnace body 7, and the aforementioned heat reflector. The heat-insulating base 11 includes a chassis 19 and a sleeve 20 fixedly fitted around the periphery of the chassis 19, with the sleeve 20 extending upwards. A mounting ring groove coaxial with the first reflector ring 1 is formed on the lower surface of the chassis 19. A fixed graphite ring 13 is placed within the mounting ring groove. An adjusting screw 3 passes through the chassis 19 and is screwed into the fixed graphite ring 13. To ensure the adjusting screw 3 is vertically aligned, it is a double-ended screw. A screw hole matching the adjusting screw 3 is pre-drilled on the fixed graphite ring 13, and the lower end of the adjusting screw 3 is screwed into the fixed graphite ring 13. The depth of the mounting ring groove is slightly greater than the thickness of the fixed graphite ring 13. By adjusting the screw 3 and locking the fixed graphite ring 13 with their threads, the fixed graphite ring 13 is prevented from contacting the bottom of the furnace body 7. This avoids the weight of components located above the fixed graphite ring 13, such as the heat reflector, insulation base 11, and adjusting screw 3, pressing down on the fixed graphite ring 13 and causing it to break. Simultaneously, the fixed graphite ring 13's absence from contact with the bottom of the furnace body 7 prevents heat dissipation, reduces heat conduction, and is beneficial for heat preservation. The fixed graphite ring 13 is made of isostatic graphite, ensuring its structural strength and the precision of the threaded hole machining. The upper thread of the adjusting screw 3 is specially designed, with the pitch P set to P = 1, 1.5, 2, or 2.5, ensuring that the height can be calculated by the number of rotations.

[0030] Before placing the first reflective ring plate 1, the adjusting nut 4 can be moved along the length of the adjusting screw 3 by rotating the adjusting nut 4. The adjusting screw 3 is vertically set at the bottom of the single crystal furnace, so the adjusting nut 4 can rise or fall during the movement along the length of the adjusting screw 3. After all the adjusting nuts 4 are adjusted, the first reflective ring plate 1 is placed on it, and then the subsequent components can be installed. By adjusting the position of the adjusting nut 4, the distance between the first reflective ring plate 1 and the bottom of the single crystal furnace can be changed to meet the requirements of the actual production process. Furthermore, the number of rotations and the current angle of the adjusting nut 4 can be determined by the indicator groove 8, thereby determining the current height of the adjusting nut 4. When the height of all the adjusting nuts 4 is consistent, the first reflective ring plate 1 can be parallel to the bottom of the single crystal furnace, thus fully ensuring the stability of the first reflective ring plate 1.

[0031] Two symmetrical vent holes 17 are provided on the side wall of the sleeve 20. Several notches 18 are provided at the end of the sleeve 20, with four notches 18 in total, to provide space for the internal support claws of the furnace body 7. The support claws mainly support the inner liner of the furnace cylinder and the inner liner insulation components, etc. The support claws are conventional prior art in this field and will not be described in detail here.

[0032] The insulation base 11 has a receiving groove 16 for accommodating multiple second insulation felts 15. Multiple pre-reserved blocks 21 are provided along the edge of the receiving groove 16, and the receiving groove 16 is integrally connected to the pre-reserved blocks 21. Each pre-reserved block 21 has an electrode hole 12 corresponding to one of the electrodes inside the single crystal furnace, and the electrode holes 12 penetrate the insulation base 11. The receiving groove 16 has an extension section, thereby increasing its area and consequently increasing the area of ​​the second insulation felts 15, thus improving the insulation performance of the insulation base 11. The depth of the receiving groove 16 can accommodate 2-3 layers of second insulation felts 15, which are also made of soft felt to further enhance the insulation effect. A graphite cover plate 14 is provided in the receiving groove 16 to seal it. The graphite cover plate 14 covers the topmost second insulation felt 15, increasing the reflection of high temperatures from the upper part and shielding the low-temperature reflection from the bottom of the furnace body 7.

[0033] 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 heat reflective screen, characterized in that: It includes a first reflective ring plate (1) and several telescopic rods for supporting the first reflective ring plate (1). The telescopic rods are vertically set at the bottom of the single crystal furnace. During the extension and retraction of the telescopic rods, the distance between the first reflective ring plate (1) and the bottom of the single crystal furnace can be changed. Several first heat-insulating felts (2) are placed on the first reflective ring plate (1). The first heat-insulating felts (2) are annular and coaxial with the first reflective ring plate (1). A second reflective ring plate (5) coaxial with the first reflective ring plate (1) is placed on the first heat-insulating felt (2) at the top.

2. The heat reflective screen as described in claim 1, characterized in that: The bottom of the first reflective ring plate (1) is provided with a plurality of grooves (9) that correspond one-to-one with the telescopic rod.

3. The heat reflective screen as described in claim 2, characterized in that: The telescopic rod includes an adjusting screw (3) and an adjusting nut (4) that cooperates with the adjusting screw (3). The adjusting screw (3) is vertically set at the bottom of the single crystal furnace, and the adjusting nut (4) is correspondingly abutted against the bottom of the groove (9).

4. The heat reflective screen as described in claim 3, characterized in that: An indicator groove (8) is provided on the end face of the adjusting nut (4) that contacts the bottom of the groove (9).

5. The heat reflective screen as described in claim 1, characterized in that: The outer edges of the first reflective ring plate (1) and the second reflective ring plate (5) are provided with multiple channels (6), and the channels (6) correspond one-to-one with the electrodes inside the single crystal furnace.

6. The heat reflective screen as described in claim 1, characterized in that: The inner hole of the second reflective ring plate (5) is fixedly connected to a downwardly extending central cylinder (10). The first heat-insulating felt (2) and the first reflective ring plate (1) are both sleeved on the central cylinder (10), and the first heat-insulating felt (2) is in contact with the outer wall of the central cylinder (10).

7. A single crystal furnace, characterized in that: The furnace body (7), the heat insulation base (11) set at the bottom of the furnace body (7), and the heat reflector as described in claim 3 or 4, the heat insulation base (11) includes a chassis (19) and a sleeve (20) fixedly sleeved on the periphery of the chassis (19), and the sleeve (20) extends upward. The lower surface of the chassis (19) is provided with an installation ring groove coaxial with the first reflector ring plate (1), and a fixed graphite ring (13) is provided in the installation ring groove. The adjusting screw (3) passes through the chassis (19) and is screwed to the fixed graphite ring (13).

8. The single crystal furnace as described in claim 7, characterized in that: The sleeve (20) has two symmetrical vent holes (17) on its side wall and several notches (18) at its end.

9. The single crystal furnace as described in claim 7, characterized in that: The heat-insulating base (11) is provided with a receiving groove (16) for accommodating multiple second heat-insulating felts (15). Multiple reserved blocks (21) are left on the edge of the receiving groove (16). Electrode holes (12) corresponding to the electrodes inside the single crystal furnace are opened on the reserved blocks (21), and the electrode holes (12) penetrate the heat-insulating base (11).

10. The single crystal furnace as described in claim 9, characterized in that: The receiving groove (16) is provided with a graphite cover plate (14) for sealing the receiving groove (16).

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