CN112725890A

CN112725890A - Crystal growth apparatus and crystal growth method

Info

Publication number: CN112725890A
Application number: CN202011566460.2A
Authority: CN
Inventors: 狄聚青; 朱刘; 赵青松; 牛晓东; 顾小英; 胡智向
Original assignee: First Rare Materials Co Ltd
Current assignee: First Rare Materials Co Ltd
Priority date: 2020-12-25
Filing date: 2020-12-25
Publication date: 2021-04-30

Abstract

The present disclosure provides a crystal growth apparatus and a crystal growth method. The crystal growth device comprises a graphite crucible, a sealing cover, a first crucible, a first sealing cover, a second crucible and a heating element. The sealing cover is provided with a first sealing space and a first through hole, the graphite crucible is accommodated in the first sealing space, and the sealing cover also encloses an accommodating groove with an upward opening; the first sealing cover is arranged at the upper end of the first crucible and forms a second sealing space with the first crucible, the first sealing cover is provided with a second through hole and a third through hole, and the second through hole is used for the seed crystal rod to pass through; the first crucible is suspended in the containing groove and can go in and out of the containing groove along the vertical direction; the second crucible is arranged in the second sealed space and is used for containing raw materials; the heating member is sleeved on the periphery of the sealing cover. The sealing cover and the first crucible are arranged independently, so that the design that the crucible is arranged in the melting furnace in the prior art is avoided, impurities in the furnace body are prevented from entering the second crucible for growing crystals, and the crystal purity is improved.

Description

Crystal growth apparatus and crystal growth method

Technical Field

The disclosure relates to the field of crystal preparation, and in particular relates to a crystal growth device and a crystal growth method.

Background

The ultrahigh-purity germanium is also called 13N germanium, and a high-purity germanium detector prepared from the ultrahigh-purity germanium has the advantages of good energy resolution, high detection efficiency, strong stability and the like in the aspects of detecting particles, particularly x and gamma rays and the like, and becomes the first choice for experimental research of nuclear physics, particle physics and celestial physics.

The preparation of the ultra-high purity germanium single crystal needs the procedures of raw material purification, zone melting, single crystal growth, processing and the like. Wherein the critical step is single crystal growth. At present, the crystal growth device for preparing the ultra-high pure germanium single crystal needs to use a furnace body. For example, patent CN105723019A published in 2016, 6, 29 describes a method for growing germanium crystals, which uses a stainless steel furnace body, a quartz barrier is placed in the stainless steel furnace body, a quartz crucible is placed inside the quartz barrier, hydrogen is introduced during crystal growth, and a graphite crucible and a heat insulating material are placed outside the quartz barrier. The existence of the furnace body easily causes impurities to enter a crucible for growing crystals, and the purity of the crystals is influenced; in addition, the furnace body equipment has higher manufacturing cost.

Disclosure of Invention

In view of the problems of the background art, it is an object of the present disclosure to provide a crystal growth apparatus and a crystal growth method, which can prevent impurities in a furnace body from entering a crucible for growing a crystal and improve the purity of the crystal without using the furnace body.

In order to achieve the above object, the present disclosure provides a crystal growth apparatus, which includes a graphite crucible, a sealing cap, a first crucible, a first sealing cap, a second crucible, and a heating element, wherein the sealing cap has a first sealing space and a first through hole for vacuumizing the first sealing space, the graphite crucible is accommodated in the first sealing space, and the sealing cap further encloses an accommodating groove with an upward opening; the first sealing cover is arranged at the upper end of the first crucible and forms a second sealing space with the first crucible, the first sealing cover is provided with a second through hole and a third through hole, and the second through hole is used for the seed crystal rod to pass through; the first crucible is suspended in the containing groove and can go in and out of the containing groove along the vertical direction; the second crucible is arranged in the second sealed space and is used for containing raw materials; the heating member is sleeved on the periphery of the sealing cover.

In one embodiment, the seal housing includes a housing body and a second seal cap disposed at a lower end of the housing body.

In an embodiment, the first sealing cover is further provided with a fourth through hole.

In one embodiment, the crystal growing apparatus further comprises a susceptor disposed on an upper surface of the second sealing lid, and the graphite crucible is supported at an upper end of the susceptor.

In one embodiment, the ratio of the diameter of the heating element to the diameter of the graphite crucible is in the range of 1.2 to 2.

In one embodiment, the crystal growing apparatus further comprises a magnetic fluid sealing device, and the seed rod and the second through hole are sealed through the magnetic fluid sealing device.

In one embodiment, the heating member covers the graphite crucible in the up-down direction.

In order to achieve the above object, the present disclosure also provides a crystal growth method for growing a crystal by using the above crystal growth apparatus, including the steps of: (A1) the method comprises the following steps Crystal raw materials are filled into the second crucible, the seed crystal rod penetrates through the second through hole in a sealing mode, the seed crystal is arranged at the lower end of the seed crystal rod, and the first crucible is lowered into the containing groove of the sealing cover and is not in contact with the cover body; (A2) the method comprises the following steps Vacuumizing the first sealed space through the first through hole, vacuumizing the second sealed space through the third through hole, and introducing hydrogen into the second sealed space through the third through hole; (A3) the method comprises the following steps And starting the heating element to heat the graphite crucible, so that the raw material in the second crucible is melted, contacting the seed crystal with the melted raw material, and then growing the crystal.

In one embodiment, the heating member covers the graphite crucible in the up-down direction; in the step (a3), after the raw material is melted, the height of the first crucible is adjusted until the liquid level of the melted raw material is in the middle of the graphite crucible in the up-down direction.

In one embodiment, in the step (a2), the first sealed space is evacuated until the air pressure reaches 10 "3 Pa; and vacuumizing the second sealed space until the air pressure reaches 10-3Pa, and then introducing hydrogen and maintaining the air pressure at 10-3 Pa.

In one embodiment, in the step (A2), the purity of the introduced hydrogen is not less than 7N, and the hydrogen flow rate is 0.1L-5L/min.

The beneficial effect of this disclosure: in the crystal growth device according to the present disclosure, the sealing cover replaces the use of the melting furnace in the prior art, and the sealing cover and the first crucible are arranged independently from each other, so that the design of arranging the crucible in the melting furnace in the prior art is avoided, thereby avoiding impurities in the furnace body from entering the second crucible for growing the crystal, and improving the crystal purity; in addition, compared with the structure of a smelting furnace, the growth device disclosed by the invention is simple in structure, small in sealing area where crystals grow, convenient to clean and capable of saving the manufacturing cost.

Drawings

FIG. 1 is a schematic view of a crystal growing apparatus according to the present disclosure.

Wherein the reference numerals are as follows:

1 graphite crucible 41 second through-hole

2 sealing cover 42 third through hole

S1 fourth through hole of the first sealed space 43

21 holding tank 5 second crucible

22 heating element of hood 6

23 second sealing cover 7 base

231 first through hole 8 support rod

3 first crucible 9 magnetofluid sealing device

S2 second sealed space R seed rod

4 first sealing cover R1 seed crystal

Detailed Description

The accompanying drawings illustrate embodiments of the present disclosure and it is to be understood that the disclosed embodiments are merely examples of the disclosure, which can be embodied in various forms, and therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure.

Referring to fig. 1, a crystal growth apparatus according to the present disclosure includes a graphite crucible 1, a sealing cap 2, a first crucible 3, a first sealing cap 4, a second crucible 5, and a heating member 6.

The hermetic cover 2 forms a first hermetic space S1 and a first through hole 231 for evacuating the first hermetic space S1. Specifically, the seal cover 2 includes a cover body 22 and a second seal cover 23.

The second sealing cover 23 is provided at the lower end of the cover body 22, and the cross sections of the cover body 22 and the second sealing cover 23 are substantially in a shape of a Chinese character 'ao'. The cover 22 and the second sealing cover 23 enclose a first sealed space S1, and the shape of the first sealed space S1 is adapted to the shape of the graphite crucible 1, so that the graphite crucible 1 can be accommodated in the first sealed space S1 without the graphite crucible 1 contacting the cover 22. In one embodiment, the first through hole 231 penetrates the second sealing cover 23. First through-hole 231 is used for communicating with outside evacuating device to carry out the evacuation to first confined space S1, thereby take out the oxygen in first confined space S1, avoid graphite crucible 1 to be heated under the oxygen circumstances and oxidized, guaranteed graphite crucible 1' S life. In one embodiment, the vacuum pumping means pumps vacuum to the first sealed space S1 until the air pressure reaches 10-3Pa, and maintains the air pressure in the first sealed space S1 at 10-3 Pa. In one embodiment, the material of the mask 22 is quartz. The second sealing cover 23 is a flange cover.

The heating member 6 is fitted around the outer periphery of the sealing cap 2. Preferably, the heating member 6 covers the graphite crucible 1 in the up-down direction, thereby ensuring that the graphite crucible 1 is heated uniformly as a whole and ensuring the crystal growth quality. In one embodiment, the heating member 6 is an induction coil for heating the graphite crucible 1 in the sealing cap 2. In one embodiment, the diameter ratio of the diameter of the induction coil to the diameter of the graphite crucible 1 is 1.2-2, and the ratio can provide a stable melting zone and temperature gradient for crystal growth, so that the forming quality of the crystal is improved.

The cover body 22 of the sealing cover 2 encloses a housing groove 21 that opens upward. The first crucible 3 is suspended in the storage tub 21 and can move in and out of the storage tub 21 in the vertical direction. The first crucible 3 is not in contact with the mantle 22, so that the risk of crushing the first crucible 3 made of quartz material and the mantle 22 due to thermal expansion deformation is avoided. The first crucible 3 is made of quartz.

The first sealing lid 4 is provided to seal the upper end of the first crucible 3 and forms a second sealed space S2 with the first crucible 3. The first sealing cover 4 is provided with a second through hole 41 and a third through hole 42, and the second through hole 41 is used for the seed rod R to pass through. The third through hole 42 is used for replacing the gas in the second sealed space S2, that is, the third through hole 42 is used for vacuumizing the second sealed space S2 and introducing hydrogen into the second sealed space S2. In one embodiment, the purity of the filled hydrogen is more than 7N, and the flow rate of the filled hydrogen is 0.1L-5L/min, so that the latent heat of crystallization can be effectively taken away, and a single crystal growth interface is stabilized. In an embodiment, the first sealing cover 4 is further provided with a fourth through hole 43, and the fourth through hole 43 is used for being opened when hydrogen is introduced into the second sealing space S2, so as to maintain the second sealing space S2 in a constant pressure state. In one embodiment, when the second sealed space S2 is filled with hydrogen gas into the second sealed space S2, the pressure in the second sealed space S2 is maintained at 10-3 Pa. In one embodiment, the first sealing cover 4 is a flange cover. The first sealing cover 4 is sealed with the seed rod R at the second through hole 41 via a magnetic fluid sealing device.

The second crucible 5 is disposed in the second sealed space S2, and the second crucible 5 is used for containing the raw material. The second crucible is made of quartz. In one embodiment, the feedstock is a feedstock for growing an ultra-high purity germanium single crystal. The grown crystal is an ultra-high purity germanium single crystal.

In the crystal growth apparatus according to the present disclosure, the sealed cover 2 replaces the use of the melting furnace of the prior art, and the sealed cover 2 and the first crucible 3 are arranged independently of each other, avoiding the design of arranging the crucible in the melting furnace of the prior art, thereby avoiding impurities in the furnace body from entering the second crucible 5 for growing the crystal, and improving the crystal purity; in addition, compared with the structure of a smelting furnace, the growth device disclosed by the invention is simple in structure, the sealing area where the crystal grows is small, the cleaning of a container is convenient, and the manufacturing cost is saved.

The crystal growing apparatus further includes a susceptor 7, the susceptor 7 being disposed on an upper surface of the second sealing cap 23, and the graphite crucible 1 being supported on an upper end of the susceptor 7. The base 7 is a quartz base, and the setting of the base 7 can prevent the direct contact between the graphite crucible 1 and the second sealing cover 23, so that the influence on the overall temperature of the graphite crucible 1 caused by the direct contact between the graphite crucible 1 and the second sealing cover 23 is avoided, and the temperature consistency of the graphite crucible 1 under the heating condition is improved.

As shown in fig. 1, the crystal growth apparatus further includes a support rod 8, a lower end of the support rod 8 is connected to the first sealing cover 4, and the support rod 8 is used for driving the first crucible 3 to move up and down, so that the first crucible 3 can enter and exit the accommodating groove 21.

The method of growing a crystal using the crystal growing apparatus of the present disclosure is explained below. The crystal growth method of the present disclosure includes the steps of: (A1) the method comprises the following steps The second crucible 5 is charged with the crystal raw material, the seed rod R is sealed through the second through hole 41 and the seed crystal R1 is mounted on the lower end of the seed rod R, the first crucible 3 is sealed, and then the first crucible 3 is lowered into the housing groove 21 of the seal cap 2 without contacting the seal cap 2. (A2) The method comprises the following steps The first sealed space S1 is evacuated through the first through hole 231, the second sealed space S2 is evacuated through the third through hole 42, and then hydrogen gas is introduced into the second sealed space S2 through the third through hole 42. (A3) The method comprises the following steps The heating element 6 is turned on to heat the graphite crucible 1 so that the raw material in the second crucible 5 is melted, the seed crystal R1 is brought into contact with the melted raw material, and then the crystal is grown.

When the crystal growth device disclosed by the invention is used for growing crystals, the crystals grow in the second sealed space S2, impurities in a smelting furnace in the prior art are prevented from entering the second sealed space S2, and the grown crystals are high in purity and few in dislocation.

In the step (A2), the first sealed space S1 was evacuated until the air pressure reached 10-3 Pa. The second sealed space S2 was evacuated until the gas pressure reached 10-3Pa, and then hydrogen gas was introduced while maintaining the gas pressure at 10-3 Pa. In order to maintain the pressure in the second sealed space S2, the fourth through hole 43 is opened to ensure that the constant pressure state of the second sealed space S2 is not affected when hydrogen gas is filled.

In the step (a3), after the raw material is melted, the height of the first crucible 3 is adjusted until the liquid level of the melted raw material is located at the middle of the graphite crucible 1 in the vertical direction, and it should be noted that the induction coil is fitted around the outer periphery of the sealing cap 2, and further, the induction coil covers the graphite crucible 1 in the vertical direction. The liquid level of the melted raw materials is positioned in the middle of the graphite crucible 1, so that a stable temperature gradient can be provided for the growth of crystals, and the quality of the grown crystals is improved. In one embodiment, the length ratio of seeding, necking, shouldering, constant diameter and ending is 1:100:40:100:20 in the crystal growth process, and the dislocation density of the formed crystal is reduced to 300-10000cm^-2. It should be noted that the molten raw material in the second crucible 5 needs to be pulled up completely, so as to prevent the second crucible 5 from cracking due to the solidification of the molten raw material or prevent the solidified solution from flowing out of the second crucible 5 onto the cover 22 to crack the cover 22, and the raw material is pulled up completely, so that the use frequency of the crystal growth device can be increased, and the safety performance of the crystal growth device can be improved.

The crystal growth apparatus and the crystal growth method according to the present disclosure grow an ultra-high purity germanium single crystal in the following embodiments.

In example 1, the diameter of the water-cooled copper induction coil was 220mm, the diameter of the graphite crucible 1 was 110mm, the hydrogen purity was 8N, and the gas flow rate was 0.1L/min. Heating to melt the high-purity germanium raw material in the second crucible 5, and then performing the processes of seeding, necking, shouldering, diameter equalization, ending and the like to finish crystal growth. The prepared crystal has a perfect appearance, the diameter of the equal-diameter part is 50mm, and the detection shows that the net carrier concentration (0.2-1.5) multiplied by 10 of the equal-diameter part of the crystal¹⁰cm^-3Dislocation of 450cm^-2-2000cm^-2。

In example 2, the diameter of the water-cooled copper induction coil was 240mm, and the diameter of the graphite crucible 1 was 200 mm. The purity of hydrogen is 7N, and the gas flow is 0.5L/min. Heating to the second crucible5, melting the high-purity germanium raw material, and completing crystal growth through the working procedures of seeding, necking, shouldering, diameter equalization, ending and the like. The prepared crystal has good appearance, the diameter of the equal-diameter part is 100mm, and the net carrier concentration of the equal-diameter part of the crystal is 0.2-1.5 multiplied by 10 through detection¹⁰cm^-3Dislocation 450-^-2. Therefore, the germanium single crystal grown by the crystal growing device and the growing method disclosed by the invention is high in purity, less in dislocation and improved in purity.

Claims

1. A crystal growth device is characterized by comprising a graphite crucible (1), a sealing cover (2), a first crucible (3), a first sealing cover (4), a second crucible (5) and a heating element (6),

the sealing cover (2) is provided with a first sealing space (S1) and a first through hole (231) for vacuumizing the first sealing space (S1), the graphite crucible (1) is accommodated in the first sealing space (S1), and the sealing cover (2) also encloses an accommodating groove (21) which is opened upwards;

the first sealing cover (4) is arranged at the upper end of the first crucible (3) in a sealing manner and forms a second sealing space (S2) with the first crucible (3), the first sealing cover (4) is provided with a second through hole (41) and a third through hole (42), and the second through hole (41) is used for a seed rod (R) to pass through;

the first crucible (3) is suspended in the containing groove (21) and can move in and out of the containing groove (21) along the vertical direction;

the second crucible (5) is arranged in the second sealed space (S2), and the second crucible (5) is used for containing raw materials;

the periphery of the sealing cover (2) is sleeved with the heating element (6).

2. Crystal growth apparatus according to claim 1, characterized in that the sealing enclosure (2) comprises an enclosure body (22) and a second sealing cover (23), the second sealing cover (23) being provided at the lower end of the enclosure body (22).

3. Crystal growth apparatus according to claim 1, characterized in that the first sealing cover (4) is further provided with a fourth through hole (43).

4. The crystal growing apparatus according to claim 1, further comprising a susceptor (7), the susceptor (7) being provided on an upper surface of the second sealing cover (23), the graphite crucible (1) being supported at an upper end of the susceptor (7).

5. A crystal growth apparatus as claimed in claim 1, characterized in that the ratio of the diameter of the heating element (6) to the diameter of the graphite crucible (1) is in the range 1.2-2.

6. The crystal growth apparatus according to claim 1, further comprising a magnetic fluid seal (9), wherein the seed rod (R) and the second through hole (41) are sealed therebetween by the magnetic fluid seal (9).

7. A crystal growth apparatus according to claim 1, characterized in that the heating member (6) covers the graphite crucible (1) in the up-down direction.

8. A crystal growth method for growing a crystal by using the crystal growth apparatus according to any one of claims 1 to 6, comprising the steps of:

(A1) the method comprises the following steps A crystal raw material is filled in the second crucible (5), a seed rod (R) is hermetically penetrated through the second through hole (41), a seed crystal (R1) is arranged at the lower end of the seed rod (R), and the first crucible (3) is descended into the containing groove (21) of the sealed cover (2) and is not contacted with the cover body (22);

(A2) the method comprises the following steps Evacuating the first sealed space (S1) through the first through hole (231), evacuating the second sealed space (S2) through the third through hole (42), and then introducing hydrogen gas into the second sealed space (S2) through the third through hole (42);

(A3) the method comprises the following steps The heating element (6) is turned on to heat the graphite crucible (1) so that the raw material in the second crucible (5) is melted, the seed crystal (R1) is brought into contact with the melted raw material, and then the crystal is grown.

9. The crystal growth method according to claim 8,

the heating element (6) covers the graphite crucible (1) along the vertical direction;

in the step (A3), after the raw material is melted, the height of the first crucible (3) is adjusted until the liquid level of the melted raw material is in the middle of the graphite crucible (1) in the up-down direction.

10. The crystal growth method according to claim 8, wherein in the step (a2), the first sealed space (S1) is evacuated until a gas pressure reaches 10 "3 Pa; the second sealed space (S2) is evacuated until the gas pressure reaches 10-3Pa, and then hydrogen gas is introduced and the gas pressure is maintained at 10-3 Pa.

11. The crystal growth method according to claim 8, wherein in the step (A2), the purity of the introduced hydrogen gas is not less than 7N, and the hydrogen gas flow rate is 0.1L-5L/min.