Seed crystal driving mechanism with center temperature measuring and weighing functions

Abstract

The invention discloses a seed crystal driving mechanism with center temperature measuring and weighing functions. The seed crystal driving mechanism comprises a cavity, a first corrugated pipe fixedly connected with the cavity, a seed crystal driving shaft, an infrared thermometer and a weighing sensor, the seed crystal driving shaft is fixed below the weighing sensor and comprises an inner shaft and an outer shaft located on the outer side of the inner shaft, the motor drives the inner shaft to rotate through a gear pair, the infrared thermometer is located at the top of a center hole of the inner shaft, the outer shaft comprises a cooling water channel, a water inlet and a water outlet, and the water outlet and the water inlet are coaxially arranged. And the axis of the water outlet and the water inlet is axially parallel to the inner shaft. The invention provides a seed crystal driving mechanism with center temperature measurement and weighing functions, and solves the problem of compatibility of center temperature measurement and crystal growth weighing of seed crystals in a silicon carbide liquid-phase furnace.

Description

Technical Field

[0001] This invention relates to the field of seed crystal monitoring technology, specifically to a seed crystal driving mechanism with center temperature measurement and weighing functions. Background Technology

[0002] In liquid-phase methods for silicon carbide (SiC) crystal growth, such as liquid-phase epitaxy or solution growth, precise temperature measurement of the seed crystal center is not a simple monitoring step, but a core technical aspect directly related to crystal quality, growth stability, and process repeatability. Its necessity is mainly reflected in the following aspects: 1. Precise control of the temperature field at the growth interface, the driving force for crystal growth: SiC crystals grow from solution, and their growth rate and morphology are highly dependent on the supercooling at the growth interface (the difference between the actual solution temperature and the equilibrium solidification point). The temperature at the seed crystal center directly reflects the supercooling state of the core region of the growth interface. Thermal field uniformity: Liquid-phase methods typically have radial and axial temperature gradients. The temperature at the seed crystal center is the "reference point" for the thermal field distribution. Precisely measuring the temperature at this point is crucial for evaluating and optimizing the entire thermal field design (such as heater layout and insulation structure), aiming to obtain a flat and stable growth interface. Uneven interfaces can lead to crystal stress, defects, and even cracking. 2. Stable growth rate and stability of solution convection growth rate: The growth rate is directly related to the interface supercooling. Monitoring the seed crystal center temperature provides real-time feedback on the stability of the growth rate and serves as a basis for process adjustments (such as power compensation). Controlling solution convection: Temperature distribution in the liquid phase process strongly influences natural and potentially forced convection (e.g., using a rotating seed crystal). The convection state affects the uniformity of solute (carbon, silicon, etc.) transport to the interface. The center temperature is a crucial parameter for understanding and controlling the convection pattern, ensuring uniform solute supply, and avoiding component overcooling (which can lead to inclusions or honeycomb structures). 3. Process repeatability and scale-up production, the process "fingerprint": The seed crystal center temperature is one of the core parameters of the process formulation. Accurately recording and reproducing this temperature profile is fundamental to achieving batch-to-batch repeatability.

[0003] In practical operation of liquid-phase methods (especially at high temperatures, typically >1800°C), insufficient monitoring methods for crystal growth and low detection accuracy during crystal growth lead to crystal growth failure or high defect rates in produced crystals. Trial and error time and material costs are high during crystal production. Existing technologies include: 1) Temperature measurement at the eccentric point of the seed crystal disk, not at the center; 2) Temperature measurement only at the center of the seed crystal, without crystal weighing function; 3) Only seed crystal weighing function without seed crystal center temperature measurement. Some existing technologies also place the weighing sensor on the atmospheric side. When stationary, the weighing accuracy is affected by atmospheric pressure and pressure differences within the chamber. When the device moves up and down, the weighing accuracy is also affected by the elasticity of the bellows, resulting in interference ranging from hundreds of grams to kilograms in the weighing value. Summary of the Invention

[0004] Purpose of the invention: This invention proposes a seed crystal driving mechanism with center temperature measurement and weighing functions, which solves the problem of compatibility between center temperature measurement of seed crystals and weighing during crystal growth in silicon carbide liquid phase furnace.

[0005] Technical Solution: This invention proposes a seed crystal driving mechanism with central temperature measurement and weighing functions, comprising a cavity, a first corrugated pipe located below the cavity, a furnace body connected to the first corrugated pipe, a seed crystal driving shaft, an infrared thermometer, and a weighing sensor; one end of the seed crystal driving shaft is located in the cavity, and the other end extends into the furnace body through the first corrugated pipe. The seed crystal driving shaft includes an inner shaft with a hollow temperature measurement channel inside and an outer shaft located outside the inner shaft. A pair of weighing sensors are provided at the top of the outer shaft, and a first gear is provided at the upper end of the inner shaft, the first gear meshing with a second gear. The second gear is fixed on the motor output shaft. The motor drives the inner shaft to rotate through the meshing of the first gear and the second gear. The infrared thermometer is provided above the hollow temperature measuring channel of the inner shaft. The outer shaft includes a water channel, an outlet pipe, and an inlet pipe located outside the inner shaft. One end of the outlet pipe is connected to the water channel, and the other end is bent upward and led out of the cavity from the top of the cavity. A second corrugated pipe is provided outside the outlet pipe located outside the cavity. One end of the inlet pipe is connected to the water channel, and the other end is bent downward and led out of the cavity from the bottom of the cavity. A second corrugated pipe is provided outside the inlet pipe located outside the cavity.

[0006] Preferably, the top end of the inner shaft is movably connected to the top end of the outer shaft via a first bearing, and the bottom end of the inner shaft is movably connected to the bottom end of the outer shaft via a second bearing.

[0007] Preferably, the outlet pipe and the inlet pipe are L-shaped, with the horizontal portions of the outlet pipe and the inlet pipe connected to and parallel to the waterway, and the vertical portions of the outlet pipe and the inlet pipe arranged coaxially.

[0008] Preferably, the water outlet pipe has an outlet at the top and the water inlet pipe has an inlet at the bottom. The outlet and the inlet are coaxially arranged, and the axis of the outlet and the inlet is parallel to the axis of the inner axis. The outlet and the inlet have the same diameter.

[0009] Preferably, the device also includes a bracket, one end of which is fixedly connected to the top of the motor, and the other end of which is fixedly connected to the top of the outer shaft.

[0010] Preferably, the load cell is axially symmetrical about the outer shaft and fixed on both sides of the top of the outer shaft. A support is provided below the load cell, and the load cell is fixed to the bottom surface inside the cavity by a bracket.

[0011] Preferably, the infrared thermometer is fixed to the top of the cavity, and a transparent glass is provided between the infrared thermometer and the top of the inner shaft, and the transparent glass is provided on the top cover of the cavity.

[0012] Preferably, the upper part of the second corrugated pipe on the outside of the water outlet pipe is sealed by a flange and a first sealing ring, and the lower part is sealed by a second sealing ring.

[0013] Preferably, the upper part of the second corrugated pipe on the outside of the water inlet pipe is sealed by a second sealing ring, and the lower part is sealed by a flange and a first sealing ring.

[0014] Preferably, one end of the first corrugated pipe is connected to the bottom of the cavity, and the other end is sealed to the top of the furnace body through a third sealing ring.

[0015] Beneficial effects: This invention forms a sealed system between the cavity and the furnace body via a first corrugated pipe. Multiple second corrugated pipes further seal the cavity. The weighing sensor and seed crystal drive shaft are positioned within this sealed system, ensuring the weighing sensor and crystal growth are in the same environment, reducing external interference and improving monitoring accuracy. Placing an infrared thermometer above the inner shaft temperature measurement channel allows direct measurement of the temperature on the back of the seed crystal disk's center. Simultaneously, symmetrically positioning the weighing sensors on both sides of the outer shaft of the seed crystal drive shaft ensures that the weight change measured by the weighing sensors is the weight of the crystal during growth, accurately capturing temperature and weight changes during crystal growth. With equal inlet and outlet diameters and identical second corrugated pipe specifications, pressure differences between the inside and outside of the cavity cancel each other out, ensuring weighing accuracy is unaffected by water inflow or outflow. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the seed crystal driving mechanism of the present invention;

[0017] Figure 2 This is an overall cross-sectional view of the seed crystal driving mechanism of the present invention;

[0018] Figure 3 This is a side sectional view of the seed crystal driving mechanism of the present invention;

[0019] Figure 4 This is a schematic diagram of the internal structure of the seed crystal driving mechanism cavity of the present invention;

[0020] Figure 5 This is a cross-sectional view of the seed crystal driving shaft of the present invention. Detailed Implementation

[0021] Reference Figures 1-5This invention proposes a seed crystal driving mechanism with central temperature measurement and weighing functions, including a cavity 1, a first bellows 2, a seed crystal driving shaft 3, an infrared thermometer 4, a flange 5, a first sealing ring 6, a second bellows 8, a second sealing ring 9, a transparent glass 10, a first gear 11, a second gear 12, a bracket 13, a motor 15, a weighing sensor 18, and a support 19; one end of the seed crystal driving shaft 3 is located inside the cavity 1 and its top end does not contact the top surface inside the cavity 1, and the other end is located inside the first bellows 2 and its bottom end is connected to the furnace body. A symmetrical weighing sensor 18 is symmetrically arranged on the upper end of the seed crystal driving shaft 3 about the axial direction. The seed crystal drive shaft 3 includes an inner shaft 16 and an outer shaft 7. The inner shaft 16 has a hollow temperature measuring channel at its center. The outer shaft 7 is located outside the inner shaft 16. The outer shaft 7 and the inner shaft 16 are fixed at both ends by a first bearing 14 and a second bearing 17, respectively. A first gear 11 is positioned above the inner shaft 16, meshing with a second gear 12. The second gear 12 is connected to the output shaft of a motor 15. The motor 15 drives the inner shaft 16 to rotate via the first gear 11 and the second gear 12. The upper end of the motor 15 is fixed to a bracket 13, and the other side of the bracket 13 is fixed to the top of the outer shaft 7. Weighing sensors 18 are symmetrically arranged on both sides of the top of the outer shaft 7. An infrared thermometer 4 is fixed to the cavity 1 by a mounting bracket. The infrared thermometer 4 is located above the inner shaft 16. A transparent glass 10 is provided between the infrared thermometer 4 and the inner shaft 16. The transparent glass 10 is located on the top cover of the cavity 1 and sealed with a sealing material. The infrared thermometer measures the temperature at the back of the seed crystal disk's center through the transparent glass 10 and the central temperature measuring channel of the inner shaft 16. The lower part of cavity 1, together with the first bellows 2 and the furnace body below, forms a sealed system, placing the weighing sensor 18, the seed crystal drive shaft 3 and the crystal growth in the same environment, eliminating external interference and improving monitoring accuracy.

[0022] The outer shaft 7 includes a water channel 22, an outlet pipe 23, an inlet pipe 24, an outlet 20, and an inlet 21. The water channel 22 is located outside the inner shaft 16. One end of the outlet pipe 23 is connected to the water channel 22, and the other end extends out of the cavity 1 from the top of the cavity 1. It is covered by a second corrugated pipe 8. The upper end of the second corrugated pipe 8 is sealed by a flange 5 and a first sealing ring 6. The lower end of the second corrugated pipe 8 is sealed to the cavity 1 by a second sealing ring 9. The outlet pipe 23 has an outlet 20 at its top. Atmospheric pressure exerts a vertically downward atmospheric pressure on the outlet 20. One end of the inlet pipe 24 is connected to the water channel 22, and the other end extends out of the cavity 1 from the bottom of the cavity 1. It is covered by a second corrugated pipe 8. The upper end of the pipe 8 is sealed to the cavity 1 by the second sealing ring 9, and the lower end of the second bellows pipe 8 is sealed to the flange 5 and the first sealing ring 6. The top of the water inlet pipe 24 is provided with a water inlet 21. After the vacuum inside the second bellows pipe 8 is evacuated, the atmospheric pressure exerts a vertical upward atmospheric pressure on the water inlet 21. Due to the presence of the second bellows pipe 8, the lower part of the cavity 1 does not exert an axial force on the water inlet 21. The water inlet 21 and the water outlet 20 have the same diameter and are coaxially arranged. The axis of the two is parallel to the axis of the inner shaft 16. The forces on the water inlet 21 and the water outlet 20 are equal in magnitude and opposite in direction, and the two cancel each other out. When the cooling water is introduced into the inner shaft of 16, the weighing accuracy of the load cell 18 is not affected.

Claims

1. A seed crystal driving mechanism with center temperature measurement and weighing functions, characterized in that, The system includes a cavity (1), a first corrugated pipe (2) located below the cavity (1), a furnace body (24) connected to the first corrugated pipe (2), a seed crystal drive shaft (3), an infrared thermometer (4), and a weighing sensor (18). One end of the seed crystal drive shaft (3) is located inside the cavity (1), and the other end extends through the first corrugated pipe (2) into the furnace body (24). The seed crystal drive shaft (3) includes an inner shaft (16) with a hollow temperature measuring channel inside and an outer shaft (7) located outside the inner shaft (16). A pair of weighing sensors (18) are provided at the top of the outer shaft (7). A first gear (11) is provided at the upper end of the inner shaft (16). The first gear (11) meshes with a second gear (12). The second gear (12) is fixed on the output shaft of a motor (15). The machine (15) drives the inner shaft (16) to rotate through the meshing of the first gear (11) and the second gear (12). The infrared thermometer (4) is provided above the hollow temperature measuring channel of the inner shaft (16). The outer shaft (7) includes a water channel (22), an outlet pipe (23) and an inlet pipe (24) located outside the inner shaft (16). One end of the outlet pipe (23) is connected to the water channel (22), and the other end is bent upward and led out of the cavity (1) from the top. A second corrugated pipe (8) is provided outside the outlet pipe (23) located outside the cavity (1). One end of the inlet pipe (24) is connected to the water channel (22), and the other end is bent downward and led out of the cavity (1) from the bottom. A second corrugated pipe (8) is provided outside the inlet pipe (24) located outside the cavity (1).

2. The seed crystal driving mechanism with center temperature measurement and weighing functions according to claim 1, characterized in that, The top end of the inner shaft (16) is movably connected to the top end of the outer shaft (7) through a first bearing (14), and the bottom end of the inner shaft (16) is movably connected to the bottom end of the outer shaft (7) through a second bearing (17).

3. The seed crystal driving mechanism with center temperature measurement and weighing functions according to claim 1, characterized in that, The outlet pipe (23) and inlet pipe (24) are L-shaped. The horizontal part of the outlet pipe (23) and inlet pipe (24) is connected to the waterway (22) and is arranged in parallel. The vertical part of the outlet pipe (23) and inlet pipe (24) is arranged coaxially.

4. The seed crystal driving mechanism with center temperature measurement and weighing functions according to claim 1, characterized in that, The water outlet pipe (23) has an outlet (20) at the top and an inlet (21) at the bottom of the water inlet pipe (24). The outlet (20) and the inlet (21) are coaxially arranged, and the axis of the outlet (20) and the inlet (21) is parallel to the axis of the inner shaft (16). The outlet (20) and the inlet (21) have the same diameter.

5. The seed crystal driving mechanism with center temperature measurement and weighing functions according to claim 1, characterized in that, It also includes a bracket (13), one end of which is fixedly connected to the top of the motor (15), and the other end is fixedly connected to the top of the outer shaft (7).

6. The seed crystal driving mechanism with center temperature measurement and weighing functions according to claim 1, characterized in that, The weighing sensor (18) is axially symmetrical about the outer shaft (7) and fixed on both sides of the top of the outer shaft (7). A support (19) is provided below the weighing sensor (18), and the weighing sensor (18) is fixed on the bottom surface inside the cavity (1) by the support (19).

7. The seed crystal driving mechanism with center temperature measurement and weighing functions according to claim 1, characterized in that, The infrared thermometer (4) is fixed on the top of the cavity (1), and a transparent glass (11) is provided between the infrared thermometer (4) and the top of the inner shaft (16). The transparent glass (11) is provided on the top cover of the cavity (1).

8. The seed crystal driving mechanism with center temperature measurement and weighing functions according to claim 1, characterized in that, The upper part of the second corrugated pipe (8) outside the outlet pipe (23) is sealed by a flange (5) and a first sealing ring (6), and the lower part is sealed by a second sealing ring (9).

9. The seed crystal driving mechanism with center temperature measurement and weighing functions according to claim 1, characterized in that, The upper part of the second corrugated pipe (8) outside the water inlet pipe is sealed by the second sealing ring (9), and the lower part is sealed by the flange (5) and the first sealing ring (6).

10. The seed crystal driving mechanism with center temperature measurement and weighing functions according to claim 3, characterized in that, One end of the first corrugated pipe (2) is connected to the bottom of the cavity (1), and the other end is sealed to the top of the furnace body (1) through the third sealing ring (23).

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