Crystal pulling furnace and vacuum pump control system for same

Abstract

The invention provides a crystal pulling furnace and a vacuum pump control system for the crystal pulling furnace. The crystal pulling furnace comprises a main furnace chamber, an auxiliary furnace chamber, a crystal pulling head, a crucible and two vacuum devices, and the vacuum device is respectively communicated with the main furnace chamber and the auxiliary furnace chamber through a three-way electric control valve. When the control module receives a pre-working instruction sent by a controller of the crystal pulling furnace through the communication module, the control module controls the vacuum pump set to act to vacuumize the vacuum chamber until the vacuum detection module detects that the air pressure in the vacuum chamber meets a pre-configured first air pressure condition; and when a working instruction sent by the controller is received, the three-way electric control valve is controlled to be communicated, and the vacuum pump set is controlled to be started until the vacuum detection module detects that the air pressure in the vacuum chamber meets a pre-configured second air pressure condition. According to the invention, the two vacuum devices are configured to ensure the normal work of the crystal pulling furnace when any one of the devices is damaged, so that the vacuum environment in the crystal pulling furnace is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal pulling, and in particular to a crystal pulling furnace and a vacuum pump control system for the crystal pulling furnace. Background Art

[0002] The manufacturing of chips starts with single crystal silicon; an important process for the production of single crystal silicon is crystal pulling; crystal pulling generally uses a crystal pulling furnace. A crystal pulling furnace is a device that heats and melts polycrystalline silicon and other materials in an inert gas environment and then uses the direct pulling method to grow single crystals; its working process mainly includes: batching, melting, crystal pulling, and finishing steps; batching is in an air environment, and then the molten silicon liquid needs to be cooled in a high vacuum environment to reduce oxidation on the surface of the silicon liquid and the entry of impurities. How to effectively ensure the vacuum environment in the crystal pulling furnace is a prerequisite for improving the quality of single crystal silicon. Summary of the invention

[0003] One of the objectives of the present invention is to provide a crystal pulling furnace and a vacuum pump control system for the crystal pulling furnace to solve the above-mentioned technical problems.

[0004] A crystal pulling furnace provided in an embodiment of the present invention comprises: a main furnace chamber, an auxiliary furnace chamber, a crystal pulling head, a crucible and two vacuum devices; the vacuum devices are respectively connected to the main furnace chamber and the auxiliary furnace chamber through a three-way electric control valve;

[0005] One air inlet end of the three-way electric control valve is connected to the first air inlet arranged at the lower end of the main furnace chamber, the other air inlet end is connected to the second air inlet arranged at the upper end of the auxiliary furnace chamber, and the air outlet end is connected to the vacuum device.

[0006] Preferably, the vacuum device comprises: a vacuum chamber and a vacuum pump group; the vacuum pump group is connected to the vacuum chamber, and the vacuum chamber is connected to the air outlet end of the three-way electric control valve.

[0007] Preferably, the vacuum pump group includes: a combination of one or more of a high-speed drain pump, a Roots pump and a molecular pump.

[0008] Preferably, the first air inlet is arranged at the bottom end of the main furnace chamber, close to the inner wall.

[0009] Preferably, a support seat is arranged at the lower end of the main furnace chamber; a first support body is arranged in the middle of the support seat; a second support body and a third support body are respectively arranged on both sides of the first support body; both ends of the first support body are respectively hinged to the crucible support body and the support seat; both ends of the second support body and the third support body are respectively hinged to the lower end of the main furnace chamber and the support seat and the second support body and the third support body are configured as a telescopic structure; the first support body, the second support body, the third support body and the first air inlet are configured in the same plane and use the plane as the action plane; the second support body extends and the third support body contracts synchronously, or the second support body extends and the third support body contracts synchronously, and the main furnace body tilts in the action plane.

[0010] Preferably, a fourth support body and a fifth support body are also arranged between the lower end of the main furnace chamber and the support seat; the two ends of the fourth support body and the fifth support body are also hinged on the lower end of the main furnace chamber and the support seat respectively; the second support body, the third support body, the fourth support body and the fifth support body are evenly distributed on a circle with the first support body as the center; the hinge mechanism corresponding to the fourth support body and the fifth support body can move on a plane parallel to the action plane.

[0011] Preferably, a first fixing structure and a second fixing structure are respectively provided at the upper end of the support base and the lower end of the main furnace chamber to fix the first support body, the second support body, the third support body, the fourth support body and the fifth support body.

[0012] Preferably, the first fixed structure includes: a first orifice plate and a plurality of first telescopic mechanisms; the first orifice plate is provided with through holes allowing the first support body, the second support body, the third support body, the fourth support body and the fifth support body to pass through; the first telescopic mechanism is arranged between the first orifice plate and the support seat and connects the first orifice plate and the support seat.

[0013] Preferably, the second fixed structure includes: a second orifice plate and a plurality of second telescopic mechanisms; the second orifice plate is provided with through holes allowing the first support body, the second support body, the third support body, the fourth support body and the fifth support body to pass through; the second telescopic mechanism is arranged between the second orifice plate and the lower end of the main furnace chamber and connects the second orifice plate and the lower end of the main furnace chamber.

[0014] The present invention also provides a vacuum pump control system for a crystal pulling furnace, which is applied to any of the above-mentioned crystal pulling furnaces, and comprises: a vacuum detection module, a pressure detection module, a control module and a communication module;

[0015] When the control module receives a pre-operation instruction sent from the controller of the crystal pulling furnace through the communication module, the control module controls the vacuum pump group to operate to evacuate the vacuum chamber, and when the vacuum detection module detects that the air pressure in the vacuum chamber meets the pre-configured first air pressure condition, the control module controls the vacuum pump group to stop operating;

[0016] When a working instruction sent by the controller is received, the three-way electric control valve is controlled to be connected and the vacuum pump group is controlled to start. When the vacuum detection module detects that the air pressure in the vacuum chamber meets the pre-configured second air pressure condition, the vacuum pump group is controlled to stop.

[0017] The present invention has the following advantages:

[0018] 1. Two vacuum devices are configured to ensure the normal operation of the crystal pulling furnace when any device is damaged, so as to ensure the vacuum environment in the crystal pulling furnace. In a vacuum environment, the surface tension of the molten silicon liquid is reduced, which makes it easier for the silicon liquid to be peeled off from the seed crystal, thereby speeding up the crystal pulling speed. The high-speed dry pump can provide a stable vacuum degree, which helps to continuously and quickly pull single crystal silicon. Improve the purity of single crystals: In a high vacuum environment, the oxidation rate of the silicon liquid surface is slowed down, reducing the formation of the oxide layer, which helps to improve the purity of single crystal silicon.

[0019] 2. Compared with traditional wet pumps, dry pumps do not involve liquid, so they are safer during operation and maintenance, while also reducing the impact on the environment.

[0020] 3. The high-speed dry pump has high efficiency and can reach the required vacuum level in a shorter time, which helps to reduce energy consumption during the drawing process.

[0021] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 Schematic diagram of a crystal pulling furnace according to an embodiment of the present invention;

[0025] Figure 2 Schematic diagram of a vacuum pump control system of a crystal pulling furnace in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0027] Example 1

[0028] The embodiment of the present invention provides a crystal pulling furnace, such as Figure 1 As shown, it comprises: a main furnace chamber 1, an auxiliary furnace chamber 2, a crystal pulling head 3, a crucible 4 and two vacuum devices 5; the vacuum device 5 is connected to the main furnace chamber 1 and the auxiliary furnace chamber 2 through a three-way electric control valve 6 respectively;

[0029] One air inlet end of the three-way electric control valve 6 is connected to the first air inlet 11 arranged at the lower end of the main furnace chamber 1, the other air inlet end is connected to the second air inlet 21 arranged at the upper end of the auxiliary furnace chamber 2, and the air outlet end is connected to the vacuum device 5.

[0030] The vacuum device 5 includes: a vacuum chamber 51 and a vacuum pump group 52 ; the vacuum pump group 52 is connected to the vacuum chamber 51 , and the vacuum chamber 51 is connected to the gas outlet end of the three-way electric control valve 6 .

[0031] The vacuum pump group 52 includes: a combination of one or more of a high-speed drain pump, a Roots pump and a molecular pump.

[0032] The present invention also provides a vacuum pump control system for a crystal pulling furnace, which is applied to the above-mentioned crystal pulling furnace, such as Figure 2 As shown, it includes: a vacuum detection module 31, a pressure detection module 32, a control module 33 and a communication module 34; the vacuum detection module 31 and the pressure detection module 32 both include a vacuum pressure gauge;

[0033] When the control module 33 receives the pre-operation instruction sent from the controller of the crystal pulling furnace through the communication module 34, the vacuum pump group is controlled to operate to evacuate the vacuum chamber, and when the vacuum detection module 31 detects that the air pressure in the vacuum chamber meets the pre-configured first air pressure condition, the vacuum pump group is controlled to stop operating;

[0034] When receiving the working instruction sent by the controller, the three-way electric control valve 6 is controlled to be connected and the vacuum pump group is controlled to start. When the vacuum detection module 31 detects that the air pressure in the vacuum chamber meets the pre-configured second air pressure condition, the vacuum pump group is controlled to stop.

[0035] The crystal pulling furnace provided in this embodiment is a vacuum crystal pulling furnace, that is, after the ingredients are prepared and the hatch is closed, the enclosed space of the main furnace chamber 1 and the auxiliary furnace chamber 2 is evacuated; the vacuum treatment process is performed by the vacuum device 5; when the staff opens the hatch to prepare the ingredients, the controller of the crystal pulling furnace sends a pre-working instruction to the vacuum pump control system, and the pre-working instruction is received by the communication module 34 and transferred to the control module 33; the communication module 34 includes: one or more combinations of RS232 communication module, RS485 communication module, USB communication module, and RS422 communication module. When the control module 33 receives the pre-work instruction, it closes the three-way electric control valve 6 to evacuate the vacuum chamber. At this time, the vacuum operation is only performed by a high-speed drain pump, and the standard to be achieved is to meet the pre-configured first air pressure condition (i.e., less than or equal to the preset first air pressure value); after the hatch is closed, when the staff presses the next step button, the controller sends a work instruction, and at this time the three-way electric control valve 6 is opened to dilute the air in the main furnace chamber 1 and the auxiliary furnace chamber 2 through the vacuum in the vacuum chamber, and then further vacuum treatment is performed by the vacuum pump group; at this time, the vacuum is first reduced to the first limit by a high-speed drain pump, and then the vacuum is further reduced by a Roots pump or a molecular pump to reach a high vacuum environment, that is, when the vacuum detection module 31 detects that the air pressure in the vacuum chamber meets the pre-configured second air pressure condition (i.e., less than or equal to the preset second air pressure value, and the second air pressure value is less than the first air pressure value), the vacuum pump group is controlled to stop. In addition, impurities will be generated during the crystal pulling process, and it is necessary to keep the vacuum pump group working in a pre-configured working mode to ensure the vacuuming action, to ensure that any bubbles that may be formed can be removed in time, and to further reduce the presence of impurities.

[0036] Example 2

[0037] Based on Example 1, the first air inlet 11 is arranged at the bottom end of the main furnace chamber 1 near the inner wall.

[0038] A support seat 74 is arranged at the lower end of the main furnace chamber 1; a first support body 71 is arranged in the middle of the support seat 74; a second support body 72 and a third support body 73 are respectively arranged on both sides of the first support body 71; both ends of the first support body 71 are respectively hinged to the crucible 4 support body and the support seat 74; both ends of the second support body 72 and the third support body 73 are respectively hinged to the lower end of the main furnace chamber 1 and the support seat 74 and the second support body 72 and the third support body 73 are configured as a telescopic structure; the first support body 71, the second support body 72, the third support body 73 and the first air inlet 11 are arranged in the same plane and the plane is used as the action plane; the second support body 72 is extended and the third support body 73 is contracted synchronously, or the second support body 72 is extended and the third support body 73 is contracted synchronously, and the main furnace body is tilted in the action plane.

[0039] A fourth support body and a fifth support body are also arranged between the lower end of the main furnace chamber 1 and the support seat 74; both ends of the fourth support body and the fifth support body are also hinged on the lower end of the main furnace chamber 1 and the support seat 74 respectively; the second support body 72, the third support body 73, the fourth support body and the fifth support body are evenly distributed on a circle with the first support body 71 as the center; the hinge mechanisms corresponding to the fourth support body and the fifth support body can move on a plane parallel to the action plane.

[0040] A first fixing structure and a second fixing structure are respectively provided at the upper end of the support base 74 and the lower end of the main furnace chamber 1 to fix the first support body 71, the second support body 72, the third support body 73, the fourth support body and the fifth support body.

[0041] The first fixed structure includes: a first orifice plate 76 and a plurality of first telescopic mechanisms 75; the first orifice plate 76 is provided with through holes that allow the first support body 71, the second support body 72, the third support body 73, the fourth support body and the fifth support body to pass through; the first telescopic mechanism 75 is arranged between the first orifice plate 76 and the support seat 74 and connects the first orifice plate 76 and the support seat 74.

[0042] The second fixed structure includes: a second orifice plate 77 and a plurality of second telescopic mechanisms 78; the second orifice plate 77 is provided with through holes allowing the first support body 71, the second support body 72, the third support body 73, the fourth support body and the fifth support body to pass through; the second telescopic mechanism 78 is arranged between the second orifice plate 77 and the lower end of the main furnace chamber 1 and connects the second orifice plate 77 and the lower end of the main furnace chamber 1.

[0043] The present invention also provides a vacuum pump control system for a crystal pulling furnace, which is applied to the above-mentioned crystal pulling furnace and includes: a vacuum detection module 31, a pressure detection module 32, a control module 33 and a communication module 34;

[0044] When the control module 33 receives the pre-operation instruction sent from the controller of the crystal pulling furnace through the communication module 34, the vacuum pump group is controlled to operate to evacuate the vacuum chamber, and when the vacuum detection module 31 detects that the air pressure in the vacuum chamber meets the pre-configured first air pressure condition, the vacuum pump group is controlled to stop operating;

[0045] When receiving the working instruction sent by the controller, the three-way electric control valve 6 is controlled to be connected and the vacuum pump group is controlled to start. When the vacuum detection module 31 detects that the air pressure in the vacuum chamber meets the pre-configured second air pressure condition, the vacuum pump group is controlled to stop.

[0046] In this embodiment, when the vacuum pump group evacuates the main furnace chamber 1 and the auxiliary furnace chamber 2, the first telescopic mechanism 75 of the first fixed structure and the second telescopic mechanism 78 of the second fixed structure are retracted to expose the hinged position, the second support body 72 gradually extends, and the third support body 73 shrinks synchronously, so that the main furnace body tilts to the other side in the action plane, and then the second support body 72 gradually shrinks, and the third support body 73 extends synchronously, and the main furnace body tilts in the opposite direction in the action plane, so that the attached trace bubbles can be discharged smoothly, and in the process of tilting, the first air inlet 11 and the second air inlet 21 on one side are always located at the top and the bottom of the space, which is more conducive to the formation of a high vacuum environment; in the crystal pulling process after the high vacuum environment is formed, the furnace body needs to be in a stable state, and at this time, the second support body 72 and the third support body 73 need to return to the initial state, and the first telescopic mechanism 75 and the second telescopic mechanism 78 extend to push the first orifice plate 76 and the second orifice plate 77 to the top of the hinged position for fixing.

[0047] Example 3

[0048] Based on Example 2, since the tilting is performed after batching, the tilting angle should not be too large, but the attached tiny bubbles should be removed as quickly as possible. Therefore, the vacuum pump control system for a crystal pulling furnace provided in this embodiment further includes: a batching parameter acquisition module, which is used to acquire parameter data of batching;

[0049] The control module 33 performs the following operations:

[0050] The parameter data of the ingredients are standardized and quantified, and the corresponding inclination angle is retrieved from the pre-configured inclination angle library based on the characteristic parameters after standard quantification as indexes, and the elongation of the second support 72 and the third support 73 is controlled based on the inclination angle and the pre-configured angle and elongation scale; wherein the characteristic parameters include: parameters representing the material type, parameters representing the specific gravity of the material, parameters representing the average particle size of the material, etc.; the inclination angle library is constructed in advance by professional personnel through analysis, and the characteristic parameters and the inclination angle are associated one-to-one in the library; the inclination angle and the elongation in the angle and elongation scale are associated one-to-one.

[0051] Example 4

[0052] On the basis of Example 2, due to the use of a method of pre-evacuating the vacuum chamber in advance, when the three-way electric control valve 6 is connected, due to the large pressure difference between the main furnace chamber 1 and the auxiliary furnace chamber 2 and the vacuum chamber, the reaction is more violent. In order to avoid bringing the material out of the crucible 4, it is necessary to control the degree, that is, the pressure difference. The first air pressure value is dynamically adjusted through the following steps to ensure that it can be applied to any batching situation, specifically, the parameter data of the batching is obtained through the batching parameter acquisition module; the control module 33 performs standard quantization on the parameter data of the batching, and retrieves the corresponding first air pressure value from the pre-configured first air pressure value determination library based on the characteristic parameters after standard quantization as indexes; wherein the characteristic parameters include: parameters representing the material type, parameters representing the specific gravity of the material, parameters representing the average particle size of the material, etc.; the first air pressure value determination library is constructed by analysis in advance by professionals, and the characteristic parameters are associated with the first air pressure value in the library in a one-to-one correspondence.

[0053] Since the first air pressure value determination library is a pre-built standard library, in actual use, the batching conditions are slightly different from the batching conditions in the data used to build the first air pressure value determination library; therefore, a correction library is proposed to be built based on the image when the first air pressure value determination library is built;

[0054] By obtaining images taken when other identical crystal pulling furnaces in the system or the current furnace are connected during historical operation, for example, obtaining the most recent N images, the similarity between the images is calculated, and the image with the largest total similarity value is used as the analysis reference image. The analysis reference image is matched with each standard image in the correction library, and the correction value associated with the matched standard image is retrieved, and the first gas pressure value is corrected according to the correction value.

[0055] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A crystal pulling furnace, comprising: The main furnace chamber, the auxiliary furnace chamber, the crystal pulling head, and the crucible are characterized in that they also include: two vacuum devices; the vacuum devices are respectively connected to the main furnace chamber and the auxiliary furnace chamber through a three-way electric control valve; One air inlet end of the three-way electric control valve is connected to the first air inlet arranged at the lower end of the main furnace chamber, the other air inlet end is connected to the second air inlet arranged at the upper end of the auxiliary furnace chamber, and the air outlet end is connected to the vacuum device.

2. The crystal pulling furnace according to claim 1, characterized in that: The vacuum device comprises: a vacuum chamber and a vacuum pump group; the vacuum pump group is connected with the vacuum chamber, and the vacuum chamber is connected with the gas outlet end of the three-way electric control valve.

3. The crystal pulling furnace according to claim 1, characterized in that: The vacuum pump group includes: a high-speed dry pump, a Roots pump and a molecular pump, or a combination of one or more thereof.

4. The crystal pulling furnace according to claim 1, characterized in that: The first air inlet is arranged at the bottom end of the main furnace chamber near the inner wall.

5. The crystal pulling furnace according to claim 4, characterized in that: A support seat is arranged at the lower end of the main furnace chamber; a first support body is arranged in the middle of the support seat; a second support body and a third support body are arranged on both sides of the first support body; two ends of the first support body are respectively hinged to the crucible support body and the support seat; two ends of the second support body and the third support body are respectively hinged to the lower end of the main furnace chamber and the support seat, and the second support body and the third support body are configured as a telescopic structure; the first support body, the second support body, the third support body and the first air inlet are arranged in the same plane and the plane is used as the action plane; The second support body extends and the third support body contracts synchronously, or the second support body extends and the third support body contracts synchronously, and the main furnace body tilts in the action plane.

6. The crystal pulling furnace according to claim 5, characterized in that: A fourth support body and a fifth support body are also arranged between the lower end of the main furnace chamber and the support seat; both ends of the fourth support body and the fifth support body are also hinged on the lower end of the main furnace chamber and the support seat respectively; the second support body, the third support body, the fourth support body and the fifth support body are evenly distributed on a circle with the first support body as the center; the hinge mechanisms corresponding to the fourth support body and the fifth support body can move on a plane parallel to the action plane.

7. The crystal pulling furnace according to claim 6, characterized in that: A first fixing structure and a second fixing structure are respectively arranged at the upper end of the support base and the lower end of the main furnace chamber to fix the first support body, the second support body, the third support body, the fourth support body and the fifth support body.

8. The crystal pulling furnace according to claim 7, characterized in that: The first fixed structure includes: a first orifice plate and a plurality of first telescopic mechanisms; the first orifice plate is provided with through holes allowing the first support body, the second support body, the third support body, the fourth support body and the fifth support body to pass through; the first telescopic mechanism is arranged between the first orifice plate and the support seat and connects the first orifice plate and the support seat.

9. The crystal pulling furnace according to claim 7, characterized in that: The second fixed structure includes: a second orifice plate and a plurality of second telescopic mechanisms; the second orifice plate is provided with through holes allowing the first support body, the second support body, the third support body, the fourth support body and the fifth support body to pass through; the second telescopic mechanism is arranged between the second orifice plate and the lower end of the main furnace chamber and connects the second orifice plate and the lower end of the main furnace chamber.

10. A vacuum pump control system for a crystal pulling furnace, applied to the crystal pulling furnace as claimed in any one of claims 1 to 9, characterized in that: include: Vacuum detection module, pressure detection module, control module and communication module; When the control module receives a pre-operation instruction sent from the controller of the crystal pulling furnace through the communication module, the control module controls the vacuum pump group to operate to evacuate the vacuum chamber, and when the vacuum detection module detects that the air pressure in the vacuum chamber meets the pre-configured first air pressure condition, the control module controls the vacuum pump group to stop operating; When a working instruction sent by the controller is received, the three-way electric control valve is controlled to be connected and the vacuum pump group is controlled to start. When the vacuum detection module detects that the air pressure in the vacuum chamber meets the pre-configured second air pressure condition, the vacuum pump group is controlled to stop.

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