TWI754508B - Apparatus and growth process of monocrystal - Google Patents

Abstract

The present invention provides an apparatus and a growth process of monocrystal. The apparatus comprises a furnace, a crucible, a heater and a deflector assembly. The deflector assembly comprises a deflector tube and a lifting device. The crucible, the heater and the deflector tube are located within the furnace. The crucible carries the silicon melt. The heater surrounds the outside of the crucible to heat the crucible. The deflector tube connects to the lifting device, and extends from the outside of the crucible to above the silicon melt. The lifting device comprises a controller to control the movement of the deflector tube, so that the interval between the deflector tube and the surface of the silicon melt can be changed. By applying this invention, the lifting rate of the ingot and the crucible can be maintained without change, thus the relative location between the melt surface and the heat field cannot be changed. It facilitates to stabilize the monocrystal growth and produce the monocrystal with high quality. Further, the present invention provides easy operations and high precision accuracy.

Description

Single crystal growth equipment and growth method

The present invention relates to the field of silicon wafer preparation, in particular to a single crystal growth device and a growth method.

The Czochralski method is a commonly used single crystal growth method, also known as the Czochralski method, or the CZ method for short. The characteristic of CZ method is that in a straight-tube furnace body, graphite resistance heating is used to melt the polysilicon in a high-purity quartz crucible, and then the seed crystal is inserted into the surface of the melt for welding, and the seed crystal is rotated at the same time, and then reversed. In the crucible, the seed crystal is slowly lifted upwards, and finally grows into a crystal rod of the required diameter and length through the processes of seeding, shoulder placement, shoulder rotation, equal diameter growth, and finishing.

The liquid port distance has a great influence on the axial temperature gradient of the single crystal growth interface. The change of the liquid port distance causes the steady state of crystal pulling to change, and the axial temperature gradient also changes. The temperature gradient at the edge and the temperature gradient in the center vary with changes as the length of the equal diameter increases. This phenomenon has serious adverse effects on the growth of defect-free single crystals. Usually within a certain range, the larger the liquid port distance, the smoother the axial temperature gradient. Therefore, in the process of crystal pulling, the axial temperature gradient can be changed by changing the lifting speed of the crucible to control the distance between the liquid openings at different equal diameter lengths. During the growth of single crystal silicon, the silicon raw material is continuously melted and consumed, resulting in the continuous drop of the molten liquid level in the crucible. The distance between the liquid openings, that is, the distance from the molten silicon liquid level to the diversion cylinder, remains unchanged. In the prior art, the crucible is usually lifted at a certain speed during the single crystal growth process, that is, the crucible is changed by changing the crucible pulling speed. position to ensure that the distance between the ports remains unchanged. The lifting speed of the crucible is usually calculated by comprehensively calculating the parameters such as the growth rate of single crystal silicon, the diameter of single crystal silicon, the diameter of the quartz crucible, and the melt density. faster. However, in the prior art, when adjusting the position of the crucible to adjust the liquid port distance, the influence of the position of the crucible on the crystal pulling quality was not considered in the early stage of the equal diameter, and the relative position of the liquid level and the thermal field could not be guaranteed, and the position of the crucible was adjusted during the equal diameter process. It will destroy the steady state of crystal pulling, and the adjustment will be slow.

In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a single crystal growth device and a growth method, which are used to solve the problem that in the prior art, the crucible position is not considered in the early stage of the equal diameter when adjusting the position of the crucible to adjust the liquid port distance. The influence on the crystal pulling quality cannot guarantee the relative position of the liquid level and the thermal field. Adjusting the position of the crucible during the equal diameter process will destroy the steady state of the crystal pulling, and the adjustment will be slow.

In order to achieve the above object and other related objects, the present invention provides a single crystal growth device, the single crystal growth device includes a furnace body, a crucible, a heater and a flow guide assembly, and the flow guide assembly includes a flow guide tube and a flow guide tube A pulling device, the crucible is located in the furnace body to carry molten silicon, the heater is arranged in the furnace body and is located at the periphery of the crucible, and is used for heating the crucible; the guide The flow tube is arranged in the furnace body and is connected with the guide tube pulling device. The flow guide tube extends from the outer side of the crucible to the top of the molten silicon. The guide tube pulling device includes a control The guide tube moves up and down under the control of the controller to change the distance between the guide tube and the molten silicon liquid level.

In one embodiment, the guide tube pulling device further includes a connecting rod and a motor, one end of the connecting rod is connected with the guide tube, and the other end extends upward to the outside of the furnace, and the motor is connected to the The connecting rod is connected with the controller, and the motor drives the connecting rod to drive the guide tube to move up and down under the control of the controller.

In one embodiment, there are multiple connecting rods, and the multiple connecting rods are symmetrically arranged on the guide tube.

In one embodiment, the guide tube includes an ear portion and a conical cylindrical portion, one end of the ear portion is adjacent to the inner wall of the furnace body, and the other end extends toward the centerline of the furnace body, so the One end of the conical cylindrical portion is connected with one end of the ear portion away from the inner wall of the furnace, and the other end extends above the crucible, and the connecting rod is connected with the ear portion.

In one embodiment, the controller is a programmable logic controller (Programmable Logic Controller, PLC), and the PLC controller is also connected to the single crystal pulling device.

In one embodiment, when the equal diameter length of the single crystal changes by a millimeter (mm), the pulling speed of the seed crystal during the change in the length of the single crystal a is b millimeters/min (mm/min). , the guide tube moves upward at the speed of c*b/a mm/min.

In one embodiment, the single crystal growth apparatus further includes a crucible lifting system for driving the crucible to move upward at a preset constant speed during the single crystal growth process.

The present invention also provides a single crystal growth method. In the single crystal growth process, the guide cylinder is moved up and down to change the distance between the guide cylinder and the molten silicon in the crucible, thereby adjusting the growth of the single crystal. Axial temperature gradient in the process.

In one embodiment, the moving speed of the guide tube is 0-0.1 mm/min, and the moving interval is 0-20 mm.

In one embodiment, the crucible moves upward at a predetermined constant speed during single crystal growth.

As described above, the single crystal growth apparatus and the single crystal growth method of the present invention have the following beneficial effects: the single crystal growth apparatus of the present invention can be changed by adjusting the height of the guide tube by adding a guide tube linkage device when necessary. There is no adjustment of the crystal pulling speed and the crucible rising speed during the whole process, so as to achieve the purpose of changing the axial temperature gradient during the single crystal growth process, and ensure the relative position of the liquid level and the thermal field. The steady state of crystal pulling is maintained, and the adjustment operation is simple and the adjustment precision is high, which is beneficial to improve the growth quality of the single crystal.

11: Furnace body

12: Crucible

13: Heater

14: Guide tube

141: Ears

142: Conical barrel

151: connecting rod

152: Motor

153: Controller

16: Fused Silicon

17: Graphite layer

18: Graphite end cap

21: seed crystal

22: Single crystal pulling device

23: Crucible drive device

d: distance between liquid ports

FIG. 1 is a schematic diagram showing the structure of the single crystal growth apparatus of the present invention.

FIG. 2 is a schematic diagram showing the relationship between the adjustment of the liquid orifice distance and the speed of the guide tube using the single crystal growth apparatus of the present invention.

The embodiments of the present invention are described below through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

Please refer to FIG. 1 to FIG. 2 , it should be noted that the diagrams provided in this embodiment only illustrate the basic concept of the present invention in a schematic way, although the diagrams only show the components related to the present invention rather than according to the actual The number, shape and size of the components are drawn during the implementation, and the type, number and ratio of the components can be arbitrarily changed in the actual implementation, and the layout of the components may also be more complicated.

As shown in FIG. 1 , the present invention provides a single crystal growth equipment, including a furnace body 11, a crucible 12, a heater 13 and a flow guide assembly, and the flow guide assembly includes a guide tube 14 and a guide tube pulling device; The furnace body 11 is the main body for single crystal growth, and the crucible 12 , the heater 13 and the guide tube 14 are all located in the furnace body 11 ; the crucible 12 is used to carry the molten silicon 16 , and the material of the crucible 12 Including but not limited to one of quartz and graphite. For example, in an example, the crucible 12 includes a graphite crucible and a quartz crucible located in the graphite crucible; and the inner surface of the crucible 12 may be made of other materials when necessary. coating, such as silicon carbide coating; the heater 13 is located on the periphery of the crucible 12 and preferably in the circumferential direction of the entire crucible, so as to uniformly heat the crucible; the heater 13 heats the crucible 12, In order to melt the solid silicon material in the crucible 12 into the liquid molten silicon 16 , the guide tube 14 is connected with the guide tube pulling device, and the guide tube 14 is removed from the crucible 12 . The outer side extends to the top of the molten silicon 16, and usually the guide tube 14 and the molten silicon 16 have a distance; the guide tube pulling device includes a controller 153, the guide tube 14 is in the The controller 153 moves up and down under the control of the controller 153 to change the distance between the guide tube 14 and the liquid surface of the molten silicon 16 , thereby adjusting the axial temperature gradient during the growth of the single crystal. The single crystal growth equipment of the present invention can keep the position of the crucible relatively fixed by adding a guide tube pulling device to change the liquid port distance d by adjusting the height of the guide tube when necessary without changing the lifting speed of the crucible. In each furnace, the relative positions of the heater, the crucible and the lower thermal field below the crucible are kept unchanged, so as to ensure the constant and consistent growth conditions of silicon single crystal in each furnace, which is beneficial to ensure the stable and consistent production quality. Compared with the traditional method of adjusting the liquid port distance d by adjusting the position of the crucible, the method can adjust the liquid port distance more quickly.

It should be noted that the initial state of the silicon material in the crucible 12 is usually solid, and it becomes the molten silicon 16 after being thermally melted. 16 The distance between the liquid levels, which is commonly known as the liquid port distance d in the industry. The guide tube 14 is a part of the graphite thermal field. During the single crystal growth process, an inert gas, such as argon gas, is introduced into the molten silicon 16 from top to bottom through the guide tube 14, which can take away the molten silicon 16. Silicon oxide (SiO) above, and for single The crystalline silicon rod is cooled to increase its axial temperature gradient (ie, the temperature in the longitudinal growth direction of the single crystal), so that the single crystal grows rapidly. The pitch d is a very important parameter in the process of growing silicon single crystal with equal diameter. Too large or too small pitch d is not conducive to the growth of single crystal, and there are different pitches corresponding to different lengths of single crystals with equal diameters. d value. In the single crystal growth process, in order to ensure the quality of the single crystal growth, it is necessary to keep the liquid orifice distance d constant during the growth of equal diameters. In the prior art, in the single crystal growth process, the crucible is lifted to compensate for the increase in the distance d between the liquid openings due to the consumption of molten silicon. However, by changing the crucible pulling speed and adjusting the position of the crucible to adjust the liquid opening distance d, the melt will change. The relative position of the heater makes the convection in the melt unstable, that is, the stable growth conditions of the single crystal are destroyed, which will cause the unstable growth rate of the silicon single crystal and reduce the quality of the silicon single crystal. In the present invention, by adjusting the position of the guide tube to maintain the steady state during the growth of the single crystal, the adverse effects on the growth of the single crystal can be minimized, which is beneficial to improve the growth quality of the single crystal.

As an example, the guide tube pulling device further includes a connecting rod 151 and a motor 152. One end of the connecting rod 151 is connected to the guide tube 14, and the other end extends upward to the outside of the furnace body 11, and can be To move up and down, the motor 152 is connected to the connecting rod 151 and the controller 153 , and the motor 152 drives the connecting rod 151 under the control of the controller 153 to drive the guide tube 14 to move up and down .

As an example, the guide tube 14 includes an ear portion 141 and a conical cylindrical portion 142. One end of the ear portion 141 is adjacent to the inner wall of the furnace body 11 (the end communicates with the gas source), and the other end faces the inner wall of the furnace body 11. The furnace body 11 extends in the direction of the center line, one end of the conical cylindrical portion 142 is connected to one end of the ear portion 141 away from the inner wall of the furnace body 11 , and the other end extends above the molten silicon 16 . The connecting rod 151 is connected with the ear portion 141 . The ear portion 141 is in a horizontal state, and the connecting rod 151 is vertically connected with the ear portion 141 to ensure that the guide tube 14 is moved up and down in a straight line, so as to precisely control the pulling speed. The conical cylindrical portion 142 is inclined, and the included angle with the horizontal plane can be 30-75°, so as to uniformly transport the inert gas to the surface of the molten silicon and avoid liquid level fluctuations. In addition, the size of the conical cylindrical portion 142 can be gradually increased in the direction toward the crucible 12, that is, in a horn shape, so that the inert gas can be supplied to the surface of the molten silicon more uniformly, and the temperature uniformity on the same plane can be improved. In order to ensure the temperature balance in the process of single crystal isometric growth.

As an example, there are multiple connecting rods 151 , and the multiple connecting rods 151 are symmetrically arranged on the guide tube 14 . For example, there are two connecting rods 151 , and the two connecting rods 151 are connected to the furnace body. The midline of 11 is centrosymmetrically distributed. Through the symmetrical distribution of a plurality of connecting rods, it is ensured that the guide tube remains stable during the up and down movement.

As an example, the controller 153 is preferably a PLC controller, so as to facilitate the expansion of the system, the PLC controller calculates and feeds back to the high-precision motor 152 that controls the up and down movement of the guide tube 14 to precisely adjust the liquid port distance d. The PLC controller is preferably also connected with the single crystal pulling device 22, or the single crystal pulling device 22 and the guiding tube pulling device can be driven by the same PLC controller, and the crystal can be adjusted in time according to the growth of the single crystal. Rod pull speed and/or deflector pull speed. It should be noted that the single crystal pulling device 22 usually includes a pulling rope and a motor part connected to the pulling rope. The PLC controller is connected to the motor part, and the other end of the pulling rope is connected to the seed crystal 21. The crystal 21 is in contact with the molten silicon 16 in the crucible 12. After the surface of the seed crystal 21 is slightly melted, the pulling rope is pulled and rotated, so that the melt is in a supercooled state and crystallized on the seed crystal 21, and is continuously pulled and rotated. During the process, cylindrical crystals are grown. With the continuous growth of the single crystal, the molten silicon level in the crucible is constantly decreasing. In order to maintain constant single crystal growth conditions, as an example, the single crystal growth apparatus further includes a crucible lifting system (not shown) for During the single crystal growth process, the crucible 12 is driven to move upward at a preset constant speed. After the single crystal growth of a desired length is completed, the crucible 12 can also be driven to descend to make the crystal rod separate from the silicon melt level. As an example, the pot-lifting system can also be controlled by the PLC controller to ensure the linkage between the various components.

In order to precisely control the pulling speed of the guide tube 14 , the motor 152 needs to have better control precision. In this embodiment, as an example, the pulling precision of the motor 152, that is, the minimum moving speed, is 0.001 mm/min. In the present invention, the connecting rod 151 moves up and down in a straight line, and the moving speed of the motor 152 is the moving speed of the guide tube 14, that is, the change in the distance d of the upper liquid port per unit length.

As an example, the single crystal growth apparatus further includes a graphite layer 17 located between the furnace body 11 and the heater 13, and the graphite layer 17 can achieve thermal insulation. in further example , the single crystal growth apparatus further includes a graphite end cap 18, the graphite end cap 18 is located on the top of the graphite layer 17, and is located at the lower part of the ear portion 141 of the guide tube 14, through the graphite layer 17 and graphite end caps 18 work together to reduce heat loss.

As an example, the single crystal growth apparatus further includes a crucible driving device 23 located at the bottom of the crucible 12 to drive the crucible 12 to rotate when necessary. Of course, the crucible driving device 23 can also be used as the aforementioned crucible lifting system for driving the crucible to move upward at a preset constant speed during the single crystal growth process.

The lifting and pulling speed of the guide tube is closely related to parameters such as the distance between the liquid ports and the length of the single crystal equal diameter. In a preferred example, when the diameter of the single crystal varies in the range of a mm, the pulling speed of the seed crystal during the change in the length of the single crystal a is b mm/min. Move upward at the speed of c*b/a (mm/min), where a, b, and c are all fixed values set according to the needs of single crystal growth. For example, when the equal diameter length of the single crystal is 1000~1050mm (that is, the change in the equal diameter length of the single crystal a is 50mm), the seed crystal pulling speed b during the change of the single crystal length is 1mm/min. , the guide tube moves upward at a speed of 1*1/50=0.02mm/min.

In an example, the liquid port distance is set according to the crystal length, and the corresponding relationship between the two is shown in Table 1:

Of course, it should be noted that the above-mentioned information is not restrictive but only exemplary. In fact, parameters such as crystal length, liquid port distance, and seed crystal pulling speed can be set as required, and these parameters have a great relationship with the size of the crystal pulling furnace, thermal field size, process parameters, etc., so the present invention is not Restrictions on specific parameters. What is important is that in the single crystal growth process of the present invention, the liquid opening distance can be changed by adjusting the height of the guide tube according to the needs, without changing the crucible rising speed, the position of the crucible can be kept relatively fixed, so that in each furnace The relative positions of the heater, the crucible and the lower thermal field below the crucible remain unchanged to ensure the constant and consistent growth conditions of silicon single crystals in each furnace, so as to ensure the stable and consistent production quality.

為設定液口距，曲線

為導流筒速度。 If the parameters are set as shown in the above table, during the crystal growth process, along with the parameters of the liquid port distance, the PLC controller drives the motor to pull the guide tube at a certain speed, thereby changing the height of the guide tube. The corresponding relationship between the liquid port distance and the speed of the guide tube is shown in Figure 2 (the premise of the corresponding relationship is that the seed crystal pulling speed is 1mm/min), where the curve

To set the port distance, the curve

is the velocity of the guide tube.

The single crystal growth equipment of the present invention is used for single crystal growth. During the entire single crystal growth process, only the lifting and stretching of the guide tube needs to be adjusted, and the crystal pulling speed and the crucible lifting speed do not need any adjustment, so the liquid level will not be changed. and the relative position of the thermal field, so that stable crystal growth can be achieved, which is beneficial to improve the quality of single crystal growth.

The present invention also provides a single crystal growth method. The single crystal growth method can be performed according to any one of the single crystal growth equipment described above. Therefore, for the introduction of the single crystal growth equipment, please refer to the foregoing content. For brevity The purpose is not repeated. In the single crystal growth method, in the single crystal growth process, the guide tube is moved up and down to change the distance between the guide tube and the molten silicon (ie, the liquid port distance), thereby adjusting the axial temperature gradient during the single crystal growth process. . The invention does not need to adjust the crystal pulling speed and the crucible rising speed, so the relative position of the liquid level and the thermal field will not be changed, which is beneficial to stabilize the single crystal growth conditions and to grow high-quality single crystals.

As an example, the moving speed of the guide tube is 0-0.1 mm/min, and the moving interval is 0-20 mm. Of course, it should be noted that, according to different growth needs, the guide tube can move up or down, so the above values are absolute values rather than relative values, that is, the upward and downward movement ranges of the guide tube are both 0 ~20mm. And as an example, during the growth of a single crystal, the crucible moves upward at a predetermined constant speed.

In summary, the present invention provides a single crystal growth apparatus and a single crystal growth method. The equipment includes a furnace body, a crucible, a heater and a guide assembly, the guide assembly includes a guide tube and a guide tube pulling device; the crucible, the heater and the guide tube are all located in the furnace body; the The crucible is used to carry molten silicon, the heater is located at the periphery of the crucible, and is used to heat the crucible, the guide tube is connected with the guide tube pulling device, and is from the outside of the crucible extending above the molten silicon, and the guide tube is spaced from the molten silicon; the guide tube pulling device includes a controller, and the guide tube moves up and down under the control of the controller , so as to change the distance between the guide tube and the molten silicon liquid level. The single crystal growth equipment of the present invention adds a guide tube linkage device to change the liquid port distance by adjusting the height of the guide tube when necessary, and the crystal pulling speed and the crucible rising speed are not adjusted in the whole process, so as to achieve The purpose of changing the axial temperature gradient during the single crystal growth process, ensuring the relative position of the liquid level and the thermal field, maintaining the steady state of crystal pulling in the process of equal diameter, and the adjustment operation is simple and the adjustment precision is high, which is conducive to improving the single crystal growth quality.

The above-mentioned embodiments merely illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present invention should still be covered by the scope of the patent application of the present invention.

11: Furnace body

12: Crucible

13: Heater

14: Guide tube

141: Ears

142: Conical barrel

151: connecting rod

152: Motor

153: Controller

16: Fused Silicon

17: Graphite layer

18: Graphite end cap

21: seed crystal

22: Single crystal pulling device

23: Crucible drive device

d: distance between liquid ports

Claims (9)

A single crystal growth equipment, comprising: a furnace body; a crucible, which is arranged in the furnace body and used to carry molten silicon; heating; and a guide assembly, including a guide tube and a guide tube pulling device; wherein, the guide tube is arranged in the furnace body and is connected with the guide tube pulling device, and the guide tube is Extending from the outside of the crucible to above the molten silicon; the guide tube pulling device includes a controller, and the guide tube moves up and down under the control of the controller to change the guide tube The distance from the molten silicon liquid level; wherein, when the length of the single crystal is changed by a millimeter (mm), the pulling speed of the seed crystal during the change of the length of the single crystal a is b mm/min (mm/min); When the mouth distance increases by c mm, the guide tube moves upward at the speed of c*b/a mm/min. The single crystal growth equipment according to claim 1, wherein the guide tube pulling device further comprises a connecting rod and a motor, one end of the connecting rod is connected with the guide tube, and the other end extends upward Outside the furnace, the motor is connected to the connecting rod and the controller, and the motor drives the connecting rod to drive the guide cylinder to move up and down under the control of the controller. The single crystal growth apparatus according to claim 2, wherein there are a plurality of the connecting rods, and the plurality of connecting rods are symmetrically arranged on the guide tube. The single crystal growth apparatus according to claim 1, wherein the guide tube includes an ear portion and a conical tube portion, one end of the ear portion is adjacent to the inner wall of the furnace body, and the other end faces toward the inner wall of the furnace body. The centerline of the furnace body extends in the direction of the center line, one end of the conical cylindrical portion is connected with one end of the ear portion away from the inner wall of the furnace body, and the other end extends above the crucible, and the connecting rod is connected to the connected to the ears. The single crystal growth apparatus according to claim 1, wherein the controller is a programmable logic controller (PLC), and the PLC controller is further connected to the single crystal pulling device. The single crystal growing apparatus according to claim 1, further comprising a crucible lifting system for driving the crucible to move upward at a preset constant speed during the single crystal growth process. A single crystal growth method, comprising: in the single crystal growth process, by moving a guide tube up and down, the distance between the guide tube and the molten silicon in the crucible is changed, thereby adjusting the single crystal growth process. The axial temperature gradient of ; among them, when the equal diameter length of the single crystal changes by a millimeter (mm), the pulling speed of the seed crystal during the change of the length of the single crystal a is b mm/min (mm/min). When c mm, the guide tube moves up at the speed of c*b/a mm/min. The single crystal growth method according to claim 7, wherein the moving speed of the guide tube is greater than 0 to 0.1 mm/min, and the moving interval is greater than 0 to 20 mm. The single crystal growth method according to claim 7, wherein the crucible moves upward at a predetermined constant speed.

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