Single crystal pulling furnace

Abstract

The present application discloses a single crystal pulling furnace, wherein at least two through holes for accommodating lifting rods are provided on the furnace cover of the pulling furnace, the upper part of the lifting rods is connected to the lifting drive component, and the lower part is connected to the lifting device for carrying the heat preservation barrel, and the lifting drive component is used to drive the lifting rod to drive the lifting device to move upward so that the heat preservation barrel leaves the main chamber of the furnace body, so that the accessories in the main chamber of the furnace body can directly exchange heat with the furnace wall. The above-mentioned single crystal pulling furnace provided by the present application can separate the heat preservation barrel from the internal accessories of the heat field, so that the internal accessories can directly exchange heat with the inner wall of the furnace platform, thereby greatly improving the cooling capacity and shortening the cooling time of the pulling furnace.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor production equipment, and in particular relates to a single crystal pulling furnace. Background Art

[0002] The main procedures for pulling single crystals using a crystal pulling furnace include loading the furnace, vacuuming, leak detection, melting materials, welding, necking, seeding, shouldering, equal diameter, finishing, segmenting, adding materials, welding, etc. When the crucible runs for a certain period of time, the furnace stops pulling, the power drops to zero, and the furnace is cooled by argon. Although the power drops to zero during the cooling process, the heating system and the plate guard are both graphite parts with a relatively large specific heat capacity, that is, the internal heat storage capacity is relatively large. Under the same circumstances, the insulation barrel is made of carbon-carbon material and the crucible is made of silicon dioxide, both of which have relatively large specific heat capacities. In addition, there is some bottom material in the crucible, and the energy contained inside is also relatively large. Since the insulation barrel cannot exchange heat with the outside world, after the crystal pulling furnace is stopped, the heat in the above objects can only be transferred through the argon medium, which results in a relatively slow cooling rate and the furnace opening time is generally greater than 7 hours.

[0003] As the size of the furnace's thermal field increases, the heat storage capacity of each internal component becomes larger and larger, and the time for cooling with argon gas becomes longer and longer. At present, the shutdown time of a 36-inch thermal field reaches more than 10 hours. High-temperature furnace opening (400°C) also accelerates the oxidation rate of thermal field components and reduces the service life of thermal field accessories. At the same time, the impact of shutdown on single crystal production capacity is increasing. Summary of the invention

[0004] To solve the above problems, the present invention provides a single crystal pulling furnace, which can separate the insulation barrel from the internal accessories of the heat field, so that the internal accessories can directly exchange heat with the inner wall of the furnace, thereby greatly improving the cooling capacity and shortening the cooling time of the crystal pulling furnace.

[0005] The present invention provides a single crystal pulling furnace, wherein at least two through holes for accommodating lifting rods are provided on the furnace cover of the crystal pulling furnace, the upper portion of the lifting rods is connected to a lifting drive component, and the lower portion is connected to a lifting device for carrying an insulation barrel, and the lifting drive component is used to drive the lifting rods to drive the lifting device to move upward so that the insulation barrel leaves the main chamber of the furnace body, so that the accessories in the main chamber of the furnace body can directly exchange heat with the furnace wall.

[0006] Preferably, in the above-mentioned single crystal pulling furnace, a portion of the outside of the lifting rod that contacts the through hole is sleeved with a bellows.

[0007] Preferably, in the above-mentioned single crystal pulling furnace, the lifting drive component is placed on a supporting platform welded above the furnace cover.

[0008] Preferably, in the above-mentioned single crystal pulling furnace, the through holes are connected by flexible shafts.

[0009] Preferably, in the above-mentioned single crystal pulling furnace, the bellows is also provided with an upper limit switch and a lower limit switch.

[0010] Preferably, in the above-mentioned single crystal pulling furnace, the lower part of the lifting rod has an opening, and the lifting device has a connecting block, and the opening and the connecting block are connected by a rope to achieve the connection between the lifting rod and the lifting device.

[0011] Preferably, in the above-mentioned single crystal pulling furnace, the rope is a molybdenum wire rope.

[0012] Preferably, in the above-mentioned single crystal pulling furnace, the length of the rope is 150 mm greater than the effective lifting height of the insulation barrel.

[0013] Preferably, in the above-mentioned single crystal pulling furnace, the lifting drive component is a stepping motor.

[0014] Preferably, in the above-mentioned single crystal pulling furnace, the lifting device includes an annular base matching the bottom of the insulation barrel, the annular base having a plurality of insulation barrel bearing portions extending radially inward, and the annular base having a plurality of connecting blocks extending upward for connecting to the lifting rod.

[0015] From the above description, it can be known that the above-mentioned single crystal pulling furnace provided by the present invention has at least two through holes for accommodating lifting rods on the furnace cover of the crystal pulling furnace, the upper part of the lifting rod is connected to the lifting drive component, and the lower part is connected to the lifting device for carrying the insulation barrel, and the lifting drive component is used to drive the lifting rod to drive the lifting device to move upward to make the insulation barrel leave the main chamber of the furnace body, so that the accessories in the main chamber of the furnace body can directly exchange heat with the furnace wall, thereby separating the insulation barrel from the internal accessories of the hot field, and making the internal accessories directly exchange heat with the inner wall of the furnace table, thereby greatly improving the cooling capacity and shortening the cooling time of the crystal pulling furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0017] Figure 1 A schematic diagram of a furnace cover in an embodiment of a single crystal pulling furnace provided by the present invention;

[0018] Figure 2A schematic diagram of a lifting device in an embodiment of a single crystal pulling furnace provided by the present invention. DETAILED DESCRIPTION

[0019] The core of the present invention is to provide a single crystal pulling furnace, which can separate the insulation barrel from the internal accessories of the heat field, so that the internal accessories can directly exchange heat with the inner wall of the furnace table, thereby greatly improving the cooling capacity and shortening the cooling time of the crystal pulling furnace.

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] An embodiment of a single crystal pulling furnace provided by the present invention is as follows: Figure 1 and Figure 2 As shown, Figure 1 A schematic diagram of a furnace cover in an embodiment of a single crystal pulling furnace provided by the present invention, Figure 2 The schematic diagram of the lifting device in the embodiment of a single crystal pulling furnace provided by the present invention is that at least two through holes 101 for accommodating lifting rods (not shown) are provided on the furnace cover 1 of the crystal pulling furnace. The opening position needs to be isolated from the water ring inside the furnace cover. The distance between the two through holes 101 can be preferably 1380 mm, so that the rope can be kept vertical during the lifting process to avoid the rope and the furnace body from scratching during the lifting process, resulting in the crystal quality being contaminated. The aperture can be preferably 30 mm. It should be noted that Figure 1 In addition to the through hole 101, there are two water cooling screen lifting holes 102, a camera observation hole 103, a throat connection position 104 and an artificial viewing window 105, which are the same as the prior art, and the upper part of the lifting rod is connected to the lifting drive component, and the lower part is connected to the lifting device 2 for carrying the insulation bucket. It should be noted that Figure 2 It is only a schematic diagram of a usable lifting device, but is not limited to this structure. It can also be any other type of lifting device that can carry an insulation barrel. The lifting drive component is used to drive the lifting rod to drive the lifting device 2 to move upward to make the insulation barrel leave the main chamber of the furnace body. In this way, the accessories in the main chamber of the furnace body can directly exchange heat with the furnace wall. The insulation barrels mentioned here include the upper, middle and lower insulation barrels inside the furnace table.

[0022] It should be noted that when the furnace is shut down, the lifting drive component is controlled to drive the lifting device upward, and the insulation barrel is pulled to a certain height. After leaving the main chamber of the furnace, the heater, plate guard, crucible, crucible and crucible bottom material in the furnace directly exchange heat with the furnace wall. There is water circulation inside the furnace wall, and the temperature will drop very quickly. The shutdown time can be reduced to within 3 hours, and it can be cooled to 250°C. At the same time, the oxidation rate of the thermal field is significantly reduced, and the service life of the thermal field is significantly improved.

[0023] It can be known from the above description that in the embodiment of the above-mentioned single crystal pulling furnace provided by the present invention, since at least two through holes for accommodating lifting rods are provided on the furnace cover of the crystal pulling furnace, the upper part of the lifting rod is connected to the lifting drive component, and the lower part is connected to the lifting device for carrying the insulation barrel. The lifting drive component is used to drive the lifting rod to drive the lifting device to move upward so that the insulation barrel leaves the main chamber of the furnace body, so that the accessories in the main chamber of the furnace body can directly exchange heat with the furnace wall. Therefore, the insulation barrel can be separated from the internal accessories of the hot field, so that the internal accessories can directly exchange heat with the inner wall of the furnace table, thereby greatly improving the cooling capacity and shortening the cooling time of the crystal pulling furnace.

[0024] In a specific embodiment of the above-mentioned single crystal pulling furnace, the part of the outside of the lifting rod that contacts the through hole 101 can be sleeved with a bellows. The bellows can better prevent the furnace from leaking. Of course, other similar tubes can also be selected, which is not limited here. Further, the bellows can also be provided with an upper limit switch and a lower limit switch, and the stroke of the lifting drive component is controlled by the upper and lower limits. The upper and lower limit switches can be controlled by an external switch or the furnace human-machine interface.

[0025] In another specific embodiment of the above-mentioned single crystal pulling furnace, the lifting drive component can be placed on a support platform welded above the furnace cover. The provision of such a support platform can better arrange various components on the furnace cover. Of course, other structures can be used to support the lifting drive component according to actual needs, which is not limited here. In another embodiment, the through holes are also connected by a flexible shaft, which can ensure the synchronization of lifting and ensure that the insulation barrel will not be greatly skewed during the lifting process.

[0026] In a preferred embodiment of the above-mentioned single crystal pulling furnace, the lower part of the lifting rod may have an opening, and the lifting device has a connecting block, and the opening and the connecting block are connected by a rope to achieve the connection between the lifting rod and the lifting device. This rope needs to be made of high-temperature resistant flexible metal, and the rope can be a molybdenum wire rope. Furthermore, the length of the rope can be 150mm greater than the effective lifting height of the insulation barrel. The reason for this is that the furnace cover and the main chamber are separated and unscrewed after the furnace is opened, and the excess length allows the operator to disassemble the lifting drive components and the lifting device.

[0027] Those skilled in the art will appreciate that the above-mentioned lifting drive component may preferably be a stepper motor, which is not only low-cost but also easy to obtain. Of course, other types of drive components may also be used, which is not limited here.

[0028] In another preferred embodiment of the above-mentioned single crystal pulling furnace, continue to refer to Figure 2 The lifting device may include an annular base 201 matching the bottom of the heat preservation barrel, the annular base 201 having a plurality of heat preservation barrel bearing portions 202 extending radially inward, and the annular base 201 having a plurality of connection blocks 203 extending upward for connecting with the lifting rod.

[0029] In this case, after the furnace is dismantled, the furnace cover is lifted up together with the lifting device and separated from the main chamber. When it is separated by 150mm, the lifting device is connected to the main chamber of the furnace body, and the lifting motor is controlled to move downward. After the molybdenum wire rope is no longer under stress, the connection between the molybdenum wire rope and the lifting rod is removed, and the furnace cover is separated from the lifting device.

[0030] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one 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 will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A single crystal pulling furnace, characterized in that: The furnace cover of the crystal pulling furnace is provided with at least two through holes for accommodating lifting rods, and the through holes are connected by flexible shafts. The upper part of the lifting rod is connected to the lifting drive component, and the lower part is connected to the lifting device for carrying the heat preservation barrel. The lifting drive component is used to drive the lifting rod to drive the lifting device to move upward to make the heat preservation barrel leave the main chamber of the furnace body, so that the heater, the plate guard, the crucible, the crucible and the bottom material of the crucible in the main chamber of the furnace body can directly exchange heat with the furnace wall; The insulation barrel comprises upper, middle and lower insulation barrels inside the furnace; The part of the lifting rod in contact with the through hole is sleeved with a bellows, and the bellows is also provided with an upper limit switch and a lower limit switch; The lifting drive component is placed on a supporting platform welded above the furnace cover; The lifting device comprises an annular base matching the bottom of the heat preservation barrel, the annular base having a plurality of heat preservation barrel bearing parts extending radially inward, and the annular base having a plurality of connection blocks extending upward for connecting with the lifting rod.

2. The single crystal pulling furnace according to claim 1, characterized in that: The lower part of the lifting rod is provided with an opening, and the lifting device is provided with a connecting block, and the opening and the connecting block are connected by a rope to realize the connection between the lifting rod and the lifting device.

3. The single crystal pulling furnace according to claim 2, characterized in that: The rope is a molybdenum wire rope.

4. The single crystal pulling furnace according to claim 3, characterized in that: The length of the rope is 150 mm greater than the effective lifting height of the heat preservation bucket.

5. The single crystal pulling furnace according to claim 1, characterized in that: The lifting drive component is a stepping motor.

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