A crystal growth apparatus

Abstract

The utility model discloses a crystal growth device belongs to crystal growth technical field. A kind of crystal growth device, including furnace body, furnace body bottom is connected and is installed with rotary table, and rotary table is connected and is installed with the crucible of being able to continuously add raw material, and the crucible outside is equipped with first heater, and furnace body upper side is equipped with material adding channel and CCD camera, and furnace body upper side is connected and is installed with furnace cylinder, and furnace cylinder upper portion is connected and is installed with first lifting mechanism, and first lifting mechanism lower side is connected and is installed with seed crystal rod, and furnace body upper side is connected and is installed with the adjustable inclination molybdenum screen device. The device is through the inner and outer cylinder of crucible, and filter screen, so that continuous feeding can be carried out without stopping, reduce growth cycle, reduce the energy waste caused by stopping, simultaneously, molybdenum screen device generates temperature gradient in furnace body by adjusting angle, so that it meets crystal growth, and steep gradient of solid-liquid interface maintains crystal stable growth.

Description

Technical Field

[0001] This invention belongs to the field of crystal growth technology, specifically a crystal growth device. Background Technology

[0002] With the rapid development of the integrated circuit (IC) industry, device manufacturers have placed more stringent requirements on IC-grade silicon single crystal materials, and large-diameter single crystal silicon is an essential substrate material for device fabrication. The Czochralski (CZ) method is currently the most important method for growing single crystals from melt. Specifically, the raw materials constituting the crystal are placed in a crucible and heated to melt. A seed crystal is then attached to the surface of the melt, and the melt is pulled up. Under controlled conditions, the atoms or molecules at the interface between the seed crystal and the melt continuously rearrange, gradually solidifying as the temperature decreases to grow a single crystal.

[0003] In the existing crystal growth equipment using the Czochralski method, since the Czochralski method relies on axial temperature gradient control, a single crystal is formed by pulling after the seed crystal comes into contact with the melt. However, there are contradictions: the bottom needs a high temperature to maintain the molten state, the solid-liquid interface needs a steep gradient to maintain stable crystal growth, and the top needs a low temperature to reduce volatilization. Furthermore, due to the limited amount of material that can be loaded at one time, the machine needs to be stopped midway to add more material, which disrupts the thermal balance, consumes a lot of energy and time, and induces stress cracks in the crystal. Utility Model Content

[0004] To address the problems of difficulty in controlling the crystal growth temperature stratification in existing crystal growth devices, the disruption of thermal balance caused by mid-process shutdowns for material feeding, the consumption of large amounts of energy, and the reduction of production efficiency, this utility model provides a crystal growth device.

[0005] This utility model is achieved through the following technical solution: A crystal growth apparatus includes a furnace body, a rotating table connected to the bottom of the furnace body, a crucible capable of continuously adding raw materials connected to the rotating table, a first heater provided on the outside of the crucible, a feeding channel and a CCD camera provided on the upper side of the furnace body, a furnace cylinder connected to the upper side of the furnace body, a first lifting mechanism connected to the upper part of the furnace cylinder, a seed crystal rod connected to the lower side of the first lifting mechanism, and an adjustable tilting molybdenum screen device connected to the top of the furnace body. The crucible includes an inner cylinder, an outer cylinder is fitted around the inner cylinder, a flow channel is provided on the inner cylinder to connect the inside and outside of the inner cylinder, and a filter screen higher than the flow channel is provided between the side walls of the inner cylinder and the outer cylinder. The molybdenum screen device includes a fixed ring connected to the top of the furnace body, a connecting rod rotatably connected to the lower side of the fixed ring, a second lifting mechanism connected to the upper side of the furnace body, a bracket connected to the lower side of the second lifting mechanism, and an arc-shaped molybdenum screen body rotatably connected to the outer side of the bracket. The convex surface of the molybdenum screen body is provided with a sliding groove, and a slider rotatably connected to the bottom of the connecting rod is slidably connected in the sliding groove.

[0006] A further improvement of this utility model is that an air inlet is provided above the furnace cylinder, and a vacuum pump is provided at the bottom of the furnace body.

[0007] A further improvement of this utility model is that a baffle is provided at the corresponding position of the air inlet.

[0008] A further improvement of this utility model is that a guide tube sleeved on the outside of the seed crystal rod is connected and installed at the top of the furnace body.

[0009] A further improvement of this invention is that a second heater is provided at the bottom of the crucible.

[0010] A further improvement of this utility model is that the inner arc surface of the molybdenum screen body is a parabolic surface.

[0011] As can be seen from the above technical solutions, the beneficial effects of this utility model are: In operation, the raw material is added to the crucible through the feeding channel. The rotary table rotates the crucible, and the heater is activated to heat it. Once the raw material is molten, the first lifting mechanism is activated to drive the seed crystal rod downwards until it contacts the molten material, thus initiating seed crystal growth. As the first lifting mechanism drives the seed crystal rod upwards, the molten material continuously crystallizes. The second lifting mechanism is controlled to extend and retract to adjust the angle of the molybdenum screen device. At different stages of crystal growth, heat is reflected back to the crucible, maintaining a lower temperature at the top of the crucible. As the crystal rod is formed, the molten material decreases and is replenished through the feeding channel. The raw material is evenly distributed onto the filter screen as the crucible rotates, and after melting, it enters the inner cylinder of the crucible through the flow channel. This device, through the inner and outer cylinders of the crucible and the filter screen, allows for continuous feeding without stopping the machine, reducing the growth cycle and minimizing energy waste caused by downtime. Simultaneously, the molybdenum screen device, by adjusting its angle, creates a temperature gradient within the furnace that is conducive to crystal growth, resulting in a steep solid-liquid interface gradient that maintains stable crystal growth. Attached Figure Description

[0012] To more clearly illustrate the technical solution of this utility model, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1This is a schematic diagram of the overall structure of this utility model.

[0014] Figure 2 This is a schematic diagram of the molybdenum screen device of this utility model.

[0015] Figure 3 This is a schematic diagram of the cross-sectional structure of the crucible of this utility model.

[0016] In the attached diagram: 1. Furnace body, 2. Rotary table, 3. Crucible, 31. Inner cylinder of crucible, 32. Outer cylinder of crucible, 33. Flow channel, 34. Filter screen, 4. First heater, 5. Feeding channel, 6. CCD camera, 7. Furnace cylinder, 71. Air inlet, 8. First lifting mechanism, 9. Seed crystal rod, 10. Molybdenum screen device, 101. Fixing ring, 102. Connecting rod, 103. Second lifting mechanism, 104. Support, 105. Molybdenum screen body, 106. Slide groove, 107. Slider, 11. Vacuum pump, 12. Baffle, 13. Guide tube, 14. Second heater. Detailed Implementation

[0017] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0018] like Figure 1-3 As shown, a crystal growth apparatus includes a furnace body 1 capable of heat preservation. A high-temperature resistant ceramic rotary table 2 driven by a servo motor is connected and installed at the bottom of the furnace body 1. A crucible 3 capable of continuously adding raw materials during normal crystal production is connected and installed on the rotary table 2. A first heater 4 is provided on the outside of the crucible 3. A feeding channel 5 and a CCD camera 6 are provided on the upper side of the furnace body 1. The end of the feeding channel 5 is smoothly transitioned to prevent impact on the crucible and has a heat preservation switch door with good heat preservation effect. A furnace cylinder 7 is connected and installed on the upper side of the furnace body 1. A first lifting mechanism 8 is connected and installed on the upper part of the furnace cylinder 7. The first lifting mechanism 8 adopts a hydraulic ceramic composite drive system. A seed crystal rod 9 is connected and installed on the lower side of the first lifting mechanism 8. An adjustable tilting molybdenum screen device 10 is connected and installed on the top of the furnace body 1. The crucible 3 includes an inner cylinder 31, an outer cylinder 32 is sleeved on the outside of the inner cylinder 31, a flow channel 33 is provided on the inner cylinder 31 to connect the inside and outside of the inner cylinder 31, and a filter screen 34 higher than the flow channel 33 is provided between the side walls of the inner cylinder 31 and the outer cylinder 32, so that the molten liquid level is lower than the height of the filter screen, and the filter screen 34 can support the polycrystalline raw material from falling into the molten pool; The molybdenum screen device 10 includes a fixing ring 101 connected and installed on the top inner side of the furnace body 1. A connecting rod 102 is rotatably connected and installed on the lower side of the fixing ring 101. A second lifting mechanism 103 is connected and installed on the upper side of the furnace body 1. The second lifting mechanism 103 adopts a water-cooled screw mechanism driven by a servo motor, which can achieve precise extension and retraction of the corresponding length. A bracket 104 is connected and installed on the lower side of the second lifting mechanism 103. A curved molybdenum screen body 105 is rotatably connected and installed on the outer side of the bracket 104. The convex surface of the molybdenum screen body 105 is provided with a sliding groove 106. A slider 107 that is rotatably connected to the bottom of the connecting rod 102 is slidably connected and installed in the sliding groove 106. There is a gap between the molybdenum screen body 105 to ensure the normal operation of the CCD camera 6 and the feeding channel 5.

[0019] In use, polycrystalline raw materials are added into crucible 3 through feeding channel 5. Rotary table 2 drives crucible 3 to rotate. First heater 4 is started to heat crucible 3. When the raw material is heated to a molten state, first lifting mechanism 8 is started to drive seed crystal rod 9 to move downward until it contacts the molten raw material. Then seed crystal introduction is performed. As the first lifting mechanism 8 drives seed crystal rod 9 to rise, the molten raw material is continuously crystallized. The second lifting mechanism 103 is controlled to extend and retract to adjust the angle of molybdenum screen device 10. At different crystal growth stages, heat is reflected back to crucible 3, thereby maintaining a lower temperature at the top of crucible 3. As the crystal rod is generated, the molten polycrystalline raw material decreases. The robotic arm is used to replenish it through feeding channel 5, so that the raw material falls evenly onto filter screen 34 as crucible 3 rotates. After melting, it enters the inner cylinder of crucible 3 through flow channel 33. This device, through the inner and outer cylinders of the crucible 3 and the filter screen 34, enables continuous feeding without stopping the machine, reducing the growth cycle and minimizing energy waste caused by downtime. At the same time, the molybdenum screen device 10 adjusts the angle to generate a temperature gradient in the furnace body 1 that conforms to crystal growth, so that the steep gradient at the solid-liquid interface maintains stable crystal growth and reduces the defect rate of regeneration after downtime.

[0020] The furnace cylinder 7 has an air inlet 71 at the top and a vacuum pump 11 at the bottom of the furnace body 1. Argon gas is introduced into the furnace through the air inlet 71 as a protective gas to protect the crystals. Since the density of argon gas is lower than that of air, as the vacuum pump 11 pumps the gas, the argon gas gradually fills the entire furnace body 1, which can better protect the entire reaction.

[0021] A baffle 12 is provided at the corresponding position of the air inlet 71. The baffle 12 can buffer the argon gas introduced from the air inlet 71, preventing the argon gas flow from causing the seed crystal rod 9 to oscillate, which would result in defects in the crystal atomic crystallization and affect the crystallization quality.

[0022] The furnace body 1 is equipped with a guide tube 13 that is fitted around the outside of the seed crystal rod 9. The guide tube 13 can guide the continuously rising and falling airflow impact, allowing the impacting airflow to enter the surrounding area, reducing the impact on the seed crystal rod 9, preventing the seed crystal rod 9 from swaying, causing growth stripes in the crystal and affecting the crystal quality.

[0023] The crucible 3 has a ring-shaped second heater 14 at its bottom. The second heater 14 is located at the bottom of the crucible 3 to provide auxiliary heating, thereby heating the area between the inner and outer cylinders of the crucible 3, increasing the heating temperature at the center of the crucible 3, sharing the heating power of the first heater 4, improving heating efficiency, and reducing the formation of impurities in the center.

[0024] The inner arc surface of the molybdenum screen body 105 is parabolic. The parabolic surface can focus and reflect heat to the center, making the temperature at the center more controllable, precisely ensuring a steep gradient at the solid-liquid interface, and maintaining stable crystal growth.

[0025] The controller can be a common PLC controller, such as Schneider Electric M258. The feeding, heating and crystal pulling processes can be controlled by setting a program. The liquid level and temperature of the molten crystal are detected by a CCD camera throughout the process, and the output power of the heater is controlled. The angle is adjusted in real time with the molybdenum screen device 10 so that the temperature above the crucible 3 is significantly lower than the temperature of the crucible, so that the crystal can grow stably.

[0026] During use, argon gas is introduced to expel the air inside the furnace body 1, preventing air from reacting with the crystals to generate impurities. Polycrystalline raw materials are added into the crucible 3 through the feeding channel 5. The rotary table 2 drives the crucible 3 to rotate, and the first heater 4 is started to heat the crucible 3. When the raw materials are heated to a molten state, the first lifting mechanism 8 is started to drive the seed crystal rod 9 to move downwards until it contacts the molten raw materials, and then seed crystal introduction is performed. As the first lifting mechanism 8 drives the seed crystal rod 9 to rise, the molten raw materials are continuously crystallized. The second lifting mechanism 103 is controlled to extend and retract to adjust the reflection angle of the molybdenum screen device 10. At different stages of crystal growth, heat is reflected back to the crucible 3, thereby maintaining a lower temperature at the top of the crucible 3. As the crystal rod is generated, the amount of molten polycrystalline raw materials decreases, and they are replenished through the feeding channel 5, so that the raw materials fall evenly onto the filter screen 34 as the crucible 3 rotates. After the crystal melts, it enters the inner cylinder 31 of the crucible through the flow channel 33. This device, by setting up a feeding channel 5, inner and outer cylinders of the crucible 3, and a filter screen 34, allows for continuous feeding without stopping the machine, reducing the growth cycle and minimizing energy waste caused by downtime. At the same time, the molybdenum screen device 10 adjusts the angle to create a temperature gradient within the furnace body 1 that is suitable for crystal growth. This steep gradient at the solid-liquid interface maintains stable crystal growth, reducing the defect rate of regeneration after downtime. The guide tube 13 and baffle 12 effectively stabilize the seed crystal rod 9, reducing swaying caused by airflow, making the crystal forming and growth process more stable and ensuring crystal quality.

[0027] 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 crystal growth apparatus, comprising a furnace body (1), characterized in that, A rotating table (2) is connected to the bottom of the furnace body (1). A crucible (3) capable of continuously adding raw materials is connected to the rotating table (2). A first heater (4) is provided on the outside of the crucible (3). A feeding channel (5) and a CCD camera (6) are provided on the upper side of the furnace body (1). A furnace cylinder (7) is connected to the upper side of the furnace body (1). A first lifting mechanism (8) is connected to the upper part of the furnace cylinder (7). A seed crystal rod (9) is connected to the lower side of the first lifting mechanism (8). An adjustable tilting molybdenum screen device (10) is connected to the top of the furnace body (1). The crucible (3) includes an inner cylinder (31), an outer cylinder (32) is sleeved on the outside of the inner cylinder (31), a flow channel (33) is provided on the inner cylinder (31) to connect the inside and outside of the inner cylinder (31), and a filter screen (34) higher than the flow channel (33) is provided between the side walls of the inner cylinder (31) and the outer cylinder (32). The molybdenum screen device (10) includes a fixed ring (101) connected to the top of the furnace body (1), a connecting rod (102) rotatably connected to the lower side of the fixed ring (101), a second lifting mechanism (103) connected to the upper side of the furnace body (1), a bracket (104) connected to the lower side of the second lifting mechanism (103), a curved molybdenum screen body (105) rotatably connected to the outer side of the bracket (104), a groove (106) is provided on the convex surface of the molybdenum screen body (105), and a slider (107) rotatably connected to the bottom of the connecting rod (102) is slidably connected in the groove (106).

2. The crystal growth apparatus according to claim 1, characterized in that, An air inlet (71) is provided above the furnace cylinder (7), and a vacuum pump (11) is provided at the bottom of the furnace body (1).

3. The crystal growth apparatus according to claim 2, characterized in that, A baffle (12) is provided at the corresponding position of the air inlet (71).

4. The crystal growth apparatus according to claim 3, characterized in that, The top of the furnace body (1) is connected to a guide tube (13) that is sleeved on the outside of the seed crystal rod (9).

5. The crystal growth apparatus according to claim 3 or 4, characterized in that, A second heater (14) is provided at the bottom of the crucible (3).

6. The crystal growth apparatus according to claim 5, characterized in that, The inner arc surface of the molybdenum screen body (105) is a parabolic surface.

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