TW202438732A - Crystal growth device - Google Patents

Abstract

A crystal growth device includes an insulator, a heater, a crucible, and a temperature sensing element. The heater is disposed in the insulator. The heater has a first and a second heating sections. The thickness of the first heating section is smaller than that of the second heating section. The crucible is disposed in the heater, and includes a seed crystal placement area in which an indium phosphide crystal seed and a liquid placement area in which a molten indium phosphide liquid is placed. The temperature sensing element is arranged between the heater and the crucible. With such configuration, only one heater is needed by the present invention to fulfill the crystal growth conditions required by the vertical gradient freeze method, so as to reduce the cost of the method and simplify the temperature control process of crystal growth.

Description

Crystal growth device

The present invention relates to a crystal growth device, and more particularly to a crystal growth device for use in a vertical gradient solidification method.

Indium phosphate (InP) is a common semiconductor material that can be used in laser diodes, optoelectronic engineering components, electronic circuit coils, optical waveguide components, etc. Among them, large-area indium phosphate wafers are considered to be the most suitable material for 5G wireless network technology.

In recent years, vertical gradient freeze (VGF) has been often used to grow indium phosphide crystals due to its advantages such as better stability, lower defect rate, clear manufacturing temperature curve and high-quality crystals.

In order to better control crystal growth, the current vertical gradient solidification method includes at least six heaters, which are connected by thermocouples. Each heater is equipped with a temperature sensor and needs to be controlled individually. During the crystal growth period, the control system controls the power of each heater according to the temperature distribution returned by the temperature sensor. However, such a large and complex control system often requires high costs to achieve. The complex control process itself and the expensive control system are the most significant disadvantages of the vertical gradient solidification method.

To solve the above problems, the present invention provides a crystal growth device that only needs one heater to meet the crystal growth conditions required by the vertical gradient solidification method, thereby reducing the cost of using the vertical gradient solidification method and simplifying the temperature control process of crystal growth.

To achieve the above-mentioned purpose, the present invention provides a crystal growth device, which is applied to the vertical gradient solidification method. The crystal growth device includes an insulator, a heater, a crucible and a temperature sensor. The heater is arranged in the insulator, and the heater has a first heating section and a second heating section, the first heating section is located above the second heating section, and the thickness of the first heating section is less than the thickness of the second heating section; the crucible is arranged in the heater, and the crucible has a seed placement area and a liquid placement area, the seed placement area is located below the liquid placement area, the seed placement area is used to place an indium phosphide seed, and the liquid placement area is used to place a molten indium phosphide liquid; the temperature sensor is arranged between the heater and the crucible.

In one embodiment, the first heating section has three first heating walls, the second heating section has a second heating wall, a third heating wall and a fourth heating wall, and three first heating walls, a second heating wall, a third heating wall and a fourth heating wall are sequentially arranged from the top to the bottom of the heater.

In one embodiment, the thickness of the first heating wall is 10 mm, the thickness of the second heating wall is 10.1 to 10.3 mm, the thickness of the third heating wall is 10.4 to 10.7 mm, and the thickness of the fourth heating wall is 11 to 11.3 mm.

In one embodiment, the heights of the first heating wall, the second heating wall, the third heating wall and the fourth heating wall are all 12.5 cm, and the temperature gradient of the heater along the axial direction every 1 cm is less than 253 degrees Celsius.

In one embodiment, the present invention further includes a crucible support member, which is disposed between the temperature sensor and the crucible.

In one embodiment, the material of the heater is graphite.

In one embodiment, the material of the crucible is pyrolytically formed boron nitride.

In one embodiment, the material of the temperature sensor is quartz.

In one embodiment, the liquid placement area is a hollow cylinder, the seed placement area is a long and narrow circular tube, and the connection between the liquid placement area and the seed placement area is in a funnel shape.

In one embodiment, the interior of the crystal growth device is filled with argon.

As described above, the present invention makes it more difficult for heat energy to be transferred to the second heating section by making the thickness of the first heating section smaller than that of the second heating section, thereby causing the temperature gradient to increase axially from the bottom to the top of the crucible. Therefore, only one heater is needed to meet the crystal growth conditions required by the vertical gradient solidification method, thereby reducing the cost of using the vertical gradient solidification method, solving the high cost problem of at least six heaters required in the prior art, and improving the complicated temperature control process in the prior art.

In order to facilitate the description of the central idea of the present invention in the above invention content column, specific embodiments are used for illustration. Various objects in the embodiments are depicted according to the proportions, sizes, deformations or displacements suitable for the description, rather than being drawn according to the proportions of the actual elements.

The directional terms mentioned in the present invention, such as "upper", "lower", "front", "back", "left", "right", "inner", "outer", "side", etc., are merely directions of the drawings; therefore, the directional terms used are used to illustrate and understand the present invention, rather than to limit the present invention, and it is necessary to explain them in advance.

Referring to FIGS. 1 to 3 , the present invention provides a crystal growth device 100, which is applied to the vertical gradient solidification method and controls the heating power by a microprocessor system. The crystal growth device 100 includes an insulator 10, a heater 20, a crucible 30, a temperature sensor 40 and a crucible support 50. The heater 20 is disposed in the insulator 10, the crucible 30 is disposed in the heater 20, the temperature sensor 40 is disposed between the heater 20 and the crucible 30, and the crucible support 50 is disposed between the crucible 30 and the temperature sensor 40.

The insulator 10 is a hollow cylinder, and is used to isolate the crystal growth environment from external interference; in the embodiment of the present invention, the diameter of the insulator 10 is 30 cm, and the height of the insulator 10 is 130 cm.

The heater 20 is generally in the shape of a hollow cylinder and is axially disposed in the insulator 10. The heater 20 has a first heating section 21 and a second heating section 22. The first heating section 21 is located above the second heating section 22, and the thickness of the first heating section 21 is smaller than that of the second heating section 22.

In the embodiment of the present invention, the material of the heater 20 is graphite, the first heating section 21 has three first heating walls 211, the second heating section 22 has a second heating wall 221, a third heating wall 222 and a fourth heating wall 223, and the three first heating walls 211, the second heating wall 221, the third heating wall 222 and the fourth heating wall 223 are sequentially arranged from the top to the bottom of the heater 20. In the embodiment, the thickness of the first heating wall 211 is 1 cm, the thickness of the second heating wall 221 is 1.01 to 1.03 cm, the thickness of the third heating wall 222 is 1.04 to 1.07 cm, the thickness of the fourth heating wall 223 is 1.1 to 1.13 cm, and the heights of the first heating wall 211, the second heating wall 221, the third heating wall 222 and the fourth heating wall 223 are all 12.5 cm.

The crucible 30 is axially arranged in the heater 20. The crucible 30 is located between the first heating wall 211 and the third heating wall 222. The crucible 30 has a seed placement area 31 and a liquid placement area 32. The seed placement area 31 is located below the liquid placement area 32. The seed placement area 31 is a thin and long round tube, and the liquid placement area 32 is a hollow cylinder. The connection between the seed placement area 31 and the liquid placement area 32 is in a funnel shape. The seed placement area 31 is used to place an indium phosphide seed 1, and the liquid placement area 32 is used to place a molten indium phosphide liquid 2. In the embodiment of the present invention, the material of the crucible 30 is pyrolytic boron nitride (Pyrolytic boron nitride, PBN), pyrolytically formed boron nitride is a high-temperature ceramic material with high electrical resistance, not easy to deform, and excellent thermal conductivity.

The temperature sensor 40 is a hollow cylinder. The temperature sensor 40 is axially disposed between the heater 20 and the crucible 30. The height of the temperature sensor 40 is greater than that of the heater 20. The temperature sensor 40 is used to sense the temperature of each section of the heater 20 and transmit the temperature back to the microprocessor system so that the microprocessor system can control the axial temperature gradient according to the temperature distribution of the heater 20. In the embodiment of the present invention, the material of the temperature sensor 40 is quartz, which is a material that is insensitive to external interference such as vibration and acceleration and has good stability.

The crucible support member 50 is disposed between the crucible 30 and the temperature sensor 40, and is used to support and fix the crucible 30. In the embodiment of the present invention, the crucible support member 50 is made of stainless steel, which is a material with strong corrosion resistance, good mechanical properties, and suitable for various high-temperature and low-temperature environments.

In the embodiment of the present invention, the maximum diameter of the crystal that can be grown by the crystal growth device 100 is 10 cm, and the maximum length of the crystal that can be grown is 20 cm. In addition, the interior of the crystal growth device 100 is filled with argon to prevent gas impurities such as water and oxygen from affecting the crystal growth process.

The present invention provides a heat source in the first heating section 21 of the heater 20, and the thickness of the first heating section 21 is smaller than that of the second heating section 22, so that heat energy is less likely to be transferred to the second heating section 22, so that the temperature gradient can be increased axially from the bottom to the top of the heater 20, and the temperature gradient can also be increased axially from the bottom to the top of the crucible 30. Therefore, the present invention only needs one heater to meet the crystal growth conditions required by the vertical gradient solidification method, thereby reducing the cost of using the vertical gradient solidification method and simplifying the temperature control process of crystal growth.

Furthermore, in the embodiment of the present invention, the axial temperature gradient of every 1 cm in the crucible 30 is less than 253 degrees Celsius. The temperature gradient in this range can form a vortex in the molten indium phosphide liquid 2 in the crucible 30. The vortex can help remove the latent heat generated during the crystal growth process, so that the surface of the front edge of the growing crystal can remain flat, thereby increasing the homogeneity and uniformity of the generated crystal.

In addition, the temperature gradient within the above range can also make the thermal stress generated during the growth process less than 20 MPa, avoiding the dislocation problem caused by excessive thermal stress, which causes defects such as local irregular arrangement of the crystal.

As described above, the present invention makes it more difficult for heat energy to be transferred to the second heating section 22 by making the thickness of the first heating section 21 smaller than the thickness of the second heating section 22, thereby realizing an axial temperature gradient increase from the bottom to the top of the crucible 30, thereby achieving the crystal growth conditions required by the vertical gradient solidification method with only one heater, thereby reducing the cost of using the vertical gradient solidification method, solving the high cost problem of at least six heaters required in the prior art, and improving the complicated temperature control process in the prior art.

The above embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Any modifications or changes that do not violate the spirit of the present invention are within the scope of protection of the present invention.

1: Indium phosphide seed crystal 2: Molten indium phosphide liquid 100: Crystal growth device 10: Insulator 20: Heater 21: First heating section 211: First heating wall 22: Second heating section 221: Second heating wall 222: Third heating wall 223: Fourth heating wall 30: Crucible 31: Seed placement area 32: Liquid placement area 40: Temperature sensor 50: Crucible support

Figure 1 is a three-dimensional cross-sectional schematic diagram of the present invention. Figure 2 is a three-dimensional schematic diagram of the heater of the present invention. Figure 3 is a schematic diagram of the temperature gradient along the axial direction of the present invention.

1: Indium phosphide seed crystal

2: Molten indium phosphide liquid

100: Crystal growth device

10: Insulator

20: Heater

21: First heating section

211: First heating wall

22: Second heating section

221: Second heating wall

222: Third heating wall

223: Fourth heating wall

30: Crucible

31: Seed placement area

32: Liquid placement area

40: Temperature sensor

50: Crucible support

Claims (10)

A crystal growth device is applied to a vertical gradient solidification method, and the crystal growth device comprises: an insulator; a heater, which is arranged in the insulator, the heater has a first heating section and a second heating section, the first heating section is located above the second heating section, and the thickness of the first heating section is less than the thickness of the second heating section; a crucible, which is arranged in the heater, the crucible has a seed placement area and a liquid placement area, the seed placement area is located below the liquid placement area, the seed placement area is used to place an indium phosphide seed, and the liquid placement area is used to place a molten indium phosphide liquid; and a temperature sensor, which is arranged between the heater and the crucible. A crystal growth device as described in claim 1, wherein the first heating section has three first heating walls, the second heating section has a second heating wall, a third heating wall and a fourth heating wall, and the three first heating walls, the second heating wall, the third heating wall and the fourth heating wall are sequentially arranged from the top to the bottom of the heater. A crystal growth device as described in claim 2, wherein the thickness of the first heating wall is 10 mm, the thickness of the second heating wall is 10.1 to 10.3 mm, the thickness of the third heating wall is 10.4 to 10.7 mm, and the thickness of the fourth heating wall is 11 to 11.3 mm. A crystal growth device as described in claim 2, wherein the heights of the first heating wall, the second heating wall, the third heating wall and the fourth heating wall are all 12.5 cm, and the temperature gradient every 1 cm along the axial direction in the heater is less than 253 degrees Celsius. The crystal growth device as described in claim 1 further comprises a crucible support member, which is arranged between the temperature sensor and the crucible. A crystal growth device as described in claim 1, wherein the material of the heater is graphite. A crystal growth device as described in claim 1, wherein the material of the crucible is pyrolytically formed boron nitride. A crystal growth device as described in claim 1, wherein the material of the temperature sensor is quartz. The crystal growth device as described in claim 1, wherein the liquid placement area is a hollow cylinder, the seed placement area is a thin and long circular tube, and the connection between the liquid placement area and the seed placement area is in the shape of a funnel. The crystal growth device as described in claim 1, wherein the interior of the crystal growth device is filled with argon.

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