CN211497865U - Device for preparing high-purity single crystal germanium by pulling method - Google Patents

Abstract

The utility model discloses a device for preparing single crystal germanium by pulling method. The device comprises a germanium single crystal growth furnace with a crucible in the cavity, a heating device is arranged around the crucible, and the cross-sectional shape of the heating device in the single crystal pulling direction It is a "<>" symmetrical structure, which surrounds the crucible in the middle. The heating device is divided into an upper heater and a lower heater. The angle between the upper heater and the lower heater is 110°~160°, and the upper heater and the lower heater are heated. Several high-frequency eddy current induction coils are arranged in the device from top to bottom to control the axial and radial gradients of the temperature field around the single crystal. The device of the utility model can regulate and control the process of preparing single crystal germanium according to production needs, and has extremely high operational flexibility and automation potential. The crystals prepared by the utility model have good crystallinity, no defects such as cracks, dislocations, bubbles, inclusions, scattering, etc., and the single crystal repetition rate is high, thereby achieving a good crystal growth effect.

Description

A device for preparing high-purity single crystal germanium by pulling method

technical field

The utility model relates to a germanium purification technology, in particular to a device for preparing high-purity single crystal germanium by a pulling method.

Background technique

Germanium is an important semiconductor material, and germanium and its compounds are widely used in electronic industry, infrared optics, optical fiber communication, chemical catalyst and other fields, and are one of the most important metals in modern information industry.

At present, there are three main growth methods of germanium single crystal: single crystal pulling method, horizontal Bridgman method and VGF method. The horizontal Bridgeman method has the advantages of fast crystal growth and low cost, but due to the D-type crystal and low utilization rate, it is difficult to grow a large-sized germanium single crystal. The crystal diameter of the VGF method is the same as that of the crucible, and a larger size germanium single crystal can theoretically be grown. However, this method is prone to parasitic nucleation at the junction of the crucible and the crystal. In addition, the crystals grown by the VGF method are mostly concave interfaces, so it is difficult to ensure the crystal yield.

The single crystal pulling method has the advantages of fast growth rate, less pollution, and good integrity of the cultivated single crystal. However, due to the low thermal conductivity of germanium single crystal material and the relatively small critical shear stress for dislocation generation, the heat in the crystal is difficult to dissipate during the growth of single crystal, and thermal stress is easily generated, which leads to the generation of dislocations and increases in value. In addition, when the pulling method crystal grows, the crystal should be pulled out of the heating zone, and the crystal is easy to crack during the cooling process, thus affecting the performance of single crystal germanium.

The traditional germanium single crystal furnace mainly includes heater, insulation material, crucible and its support. When working, the germanium raw material is heated and melted into a melt in a crucible, and the seed crystal is brought into contact with the liquid level of the melt at a suitable temperature, and then slowly pulled upward to form a germanium single crystal rod by controlling the pulling speed and temperature. Due to the limitation of objective factors such as the thermal field and the thermal conductivity of the germanium single crystal rod, excessive pulling speed will lead to defects such as dislocations and bubbles, and even lead to uncontrolled crystal pulling or pulling of the crystal rod from the liquid level.

Utility model content

The technical problem to be solved by the utility model is to overcome the deficiencies and defects mentioned in the above background technology, and provide a device for preparing high-purity single crystal germanium by pulling method, and the obtained crystal has good crystallinity and no defects such as cracking.

In order to solve the above-mentioned technical problems, the technical scheme proposed by the present utility model is:

A device for preparing high-purity single crystal germanium by pulling method, comprising a germanium single crystal growth furnace provided with a crucible in the cavity, a heating device is arranged around the crucible, and the cross-sectional shape of the heating device in the single crystal pulling direction is "< >”-shaped symmetrical structure, the crucible is surrounded in the middle, the heating device is divided into an upper heater and a lower heater, the angle between the upper heater and the lower heater is 110°～160°, and the upper heater and the lower heater are both Several high-frequency eddy current induction coils are arranged uniformly from top to bottom to control the axial and radial gradients of the temperature field around the single crystal.

Further, both the upper heater and the lower heater are composed of at least three high-frequency eddy current induction coils connected in series.

Further, the crucible is made of metal iridium.

Further, the furnace wall of the germanium single crystal growth furnace is composed of a heat preservation cover, and the heating device is arranged in the heat preservation cover. The heat preservation cover includes a first heat preservation cover and a second heat preservation cover. Surrounding, the second heat preservation cover surrounds the crucible and the heating device from the bottom surface and the top surface, and surrounds the first heat preservation cover from the side.

Further, a crucible lowering mechanism is provided at the bottom of the crucible, and the crucible lowering mechanism includes a support column and a crucible lowering driving device. The upper end of the supporting column is connected to the bottom of the crucible, and the lower end is connected to the lowering pot driving device. It can lift and rotate up and down.

Further, the support column includes a cooling device axially arranged at the center of the support column, and the upper end of the cooling device is in contact with the center of the crucible.

Further, the support column also includes an auxiliary heating device arranged on the periphery of the cooling device, the upper end of the auxiliary heating device is in contact with the bottom of the crucible, and a first thermal insulation layer is arranged between the cooling device and the auxiliary heating device to separate the two, and the auxiliary heating device A second thermal insulation layer is arranged on the periphery of the heating device to constitute the outermost layer of the support column.

Thermal field configuration is the most critical link in pulling low-dislocation single crystals. During crystal growth, if the thermal stress in the crystal exceeds the critical shear stress for generating dislocations, the crystal will generate dislocations. Once dislocations are generated in the crystal, according to the dislocation nucleation theory, the dislocations will multiply in large quantities, and a low-dislocation single crystal cannot be obtained. The thermal stress in the crystal is directly related to the temperature gradient of the thermal field. After theoretical deduction, the conditions under which the axial temperature gradient and radial temperature gradient do not cause dislocations are:

where β is the thermal expansion coefficient, b is the Burgs vector value, G is the shear modulus, τ is the critical stress, R is the single crystal radius, and l is the single crystal length. It can be seen from the above formula that in order to prevent dislocations in the single crystal, both the axial temperature gradient and the radial temperature gradient in the single crystal are required to be relatively small.

In addition, when the crystal is grown by the pulling method, the crystal needs to be pulled out of the heating zone, and the temperature gradient is large, and the crystal is easy to crack during the cooling process. In order to reduce the crystal cracking, it is also necessary to adjust the temperature gradient of the crystal.

Through the improvement of the device and the method, the utility model can precisely control the temperature field and the temperature gradient in the single crystal, set the temperature gradient within a small range, and avoid the defects of cracking and dislocation.

Compared with the prior art, the beneficial effects of the present utility model are:

(1) The utility model installs a plurality of induction coils in the heating device on both sides of the crucible, adopts a unique "<>"-shaped heating structure, and has a fast heating rate. In the stage of melting the material, the heat can be rapidly concentrated to melt the material, and the material can be melted by Adjust the power of the coil to precisely control the temperature field, so that the crystal grows directionally along the seed crystal plane to avoid crystal cracking.

(2) By arranging an auxiliary heating device in the support column, the rate of materialization can be further accelerated, and the heating of the crucible can be made more uniform.

(3) By arranging a cooling device at the center of the bottom of the crucible, the crystallization speed can be accelerated, the ingot pulling speed can be increased, the production efficiency can be increased, the single crystal pulling speed can be increased by 1.5 to 3 times, and the process time can be shortened by 20% to 40%.

(4) The whole device of the utility model has good heat preservation and heat insulation effect, excellent air tightness and good technological effect.

(5) The device of the present invention can regulate and control the process of preparing single crystal germanium according to production needs, and has extremely high operational flexibility and automation potential.

(6) The crystals prepared by the utility model have good crystalline properties, the crystals have no defects such as cracking, dislocation, bubbles, inclusions, scattering, etc., the single crystal repetition rate is high, and a good crystal growth effect is achieved.

Description of drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative efforts.

1 is a schematic structural diagram of a device for preparing single crystal germanium by a pulling method according to an embodiment of the present utility model;

Among them: 1. Germanium single crystal growth furnace; 2. Base; 3. Top cover; 4. Support frame; 5. Crucible; 6. Melt; 7. Seed crystal; 8. Pull rod; 9. Support seat; 10. 1st thermal insulation cover; 11, second thermal insulation cover; 12, pulling driving device; 13, lowering pot driving device; 14, cooling device; 15, first thermal insulation layer; 16, auxiliary heating device; 17, second Thermal insulation layer; 18, heating device; 19, upper heater; 20, lower heater; 21, air inlet pipe; 22, air outlet pipe.

Detailed ways

In order to facilitate the understanding of the present utility model, the present utility model will be described more comprehensively and in detail below with reference to the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present utility model is not limited to the following specific embodiments.

Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.

As shown in FIG. 1 , a device for preparing high-purity single crystal germanium by pulling method according to a specific embodiment of the present invention includes a germanium single crystal growth furnace 1 , a base 2 , a top cover 3 , a support frame 4 , and a lifting mechanism , the pot lowering mechanism, the air inlet pipe 21 and the air outlet pipe 22.

The base 2 and the top cover 3 are respectively arranged at the bottom and the top of the single crystal growth furnace, and the two are fixed by the support frame 4 .

The germanium single crystal growth furnace 1 includes a crucible 5 arranged in the center of the furnace body, a heating device 18 arranged around the crucible 5 , and a heat preservation cover arranged around the heating device 18 . Preferably, the crucible 5 is made of metal iridium, which can effectively absorb heat radiation to achieve heat preservation, so as to achieve the purpose of reducing the crystal temperature gradient.

The heating device 18 has a "<>" symmetrical structure, and is divided into an upper heater 19 and a lower heater 20, and the included angle between the upper heater 19 and the lower heater 20 is 110°-160°. The upper heater 19 and the lower heater 20 are equipped with a plurality of high-frequency eddy current induction coils and are equipped with high-performance temperature detectors. Preferably, both the upper heater 19 and the lower heater 20 are composed of at least three heating coils connected in series, so that each coil is evenly distributed in the heater from top to bottom, and the power of a single heating coil is 10-30KW. Preferably, the high-frequency eddy current induction coil is a double-layer coil with a width of 1-5 cm. The heating device 18 has a fast heating rate, and can quickly concentrate heat to melt the material in the stage of melting the material. It can also precisely control the temperature field by adjusting the coil power, so that the crystal grows directionally along the seed crystal surface to avoid crystal cracking. The growth of the single crystal is substantially at the central region of the "<>" shaped structure, and the axial and radial temperature gradients within the single crystal can be controlled by controlling the power of the upper heater 19 and lower heater 20 coils, respectively.

The heat preservation cover includes a first heat preservation cover 10 and a second heat preservation cover 11 . The first heat preservation cover 10 wraps the heating device 18 from the surrounding sides, the second heat preservation cover 11 wraps the crucible 5 and the heating device 18 from the bottom surface and the top surface, and wraps the first heat preservation cover 10 from the surrounding sides. Preferably, the first heat preservation cover 10 is made of high-purity graphite material, and the second heat preservation cover 11 is made of high-purity quartz material, so as to ensure internal heat preservation and external heat insulation.

The garbage lifting mechanism includes a pulling rod 8 and a pulling driving device 12 . The upper end of the pulling rod 8 is connected to the pulling driving device 12 , and the lower end is connected to the seed crystal 7 . Preferably, the pulling rod 8 is a quartz rod. The pulling driving device 12 is fixedly arranged on the top cover 3, and the pulling driving device 12 includes a driving motor. The pulling rod 8 is rotated and pulled under the drive of the driving motor. The control end of the driving motor is electrically connected with an electric control box. The electric control box is installed on the top cover 3. The electric control box can display the pulling speed, the rotation speed and the lifting speed. Pull length.

The pot lowering mechanism includes a support base 9 , a support column and a pot lowering driving device 13 . The support base 9 is arranged at the bottom of the crucible 5 , the upper end of the support column is connected to the bottom of the crucible 5 through the support base 9 , and the lower end is connected to the crucible lowering driving device 13 .

The lowering pot driving device 13 is provided on the base 2 . In a specific embodiment, the pot lowering driving device 13 includes a driving motor, the control end of the driving motor is electrically connected with an electric control box, the electric control box is installed on the base 2, and the electric control box can display the lowering speed, rotation speed and rotation speed of the pot. Speed and descent length. The support column can lift up and down and rotate under the drive of the crucible lowering driving device 13 , so as to provide support and rotational drive for the crucible 5 . The rotation direction of the crucible 5 is opposite to the rotation direction of the pull rod 8 .

In a specific embodiment, the support column is a multi-layer structure, distributed along a plurality of concentric rings of radial cross-section, and includes an auxiliary heating device 16, a cooling device 14 and a thermal insulation layer.

The cooling device 14 is arranged at the center of the support column, at the center of the bottom of the crucible 5, and its upper end is in contact with the bottom of the crucible 5, and conducts heat exchange with the reverse convection at the center of the germanium melt to cool the solid-liquid interface, thereby accelerating the crystallization rate. , to increase the pulling speed. Preferably, the cooling device 14 adopts a cooling sleeve, into which a heat exchange medium is passed, and the heat exchange medium is cooling water or cold air, and the cooling sleeve can rise and fall synchronously with the support column.

The upper end of the auxiliary heating device 16 is in contact with the bottom of the crucible 5 . The rate of materialization can be further accelerated, and the crucible heating can be made more uniform. Preferably, the auxiliary heating device 16 is a resistance wire or a copper heating tube. The auxiliary heating device 16 can rise and fall synchronously with the support column.

The thermal insulation layers are symmetrically distributed on both sides of the cooling device 14 to separate the cooling device 14 from the auxiliary heating device 16 . The thermal insulation layer includes a first thermal insulation layer 15 and a second thermal insulation layer 17 . The first thermal insulation layer 15 is arranged on the periphery of the cooling device 14 . The auxiliary heating device 16 is arranged on the periphery of the first thermal insulation layer 15, and the second thermal insulation layer 17 is arranged on the periphery of the auxiliary heating device 16 to form the outermost layer of the support column. Preferably, the material of the first thermal insulation layer 15 is graphite soft felt, and the material of the second thermal insulation layer 17 is Al ₂ O ₃ ceramics.

A method for preparing high-purity single-crystal germanium according to a specific embodiment of the present invention uses 7N high-purity germanium as a seed crystal, and uses 5N germanium obtained by regional smelting as a raw material, comprising the following steps:

S1: vacuumize, first place the 5N germanium raw material in the crucible 5, vacuum the crucible 5 for 1-2 times, and fill with nitrogen at 1-6L/min from the air inlet pipe 21. The purity of the nitrogen introduced is greater than 5N, and the exhaust gas The collection process is performed in the air outlet pipe 22;

S2: In the chemical material stage, the power of the high-frequency eddy current induction coil of the heating device 18 is gradually increased in the early stage, and the auxiliary heating device 16 is turned on at the same time to heat the raw material to the first temperature. The chemical power is reduced by 5-20%, so that the raw materials in the crucible are melted, given a fixed crucible rotation, the crucible rotation is between 1-4r/min, and the growth is maintained for 2-6h;

S3: In the crystal growth stage, the auxiliary heating device 16 is turned off, and the cooling device 14 is turned on at the same time. The power of the induction coil is reduced by 10%-30% compared with the power of the chemical material in the later stage of the material chemical stage, and the temperature is lowered to the second temperature at the first rate. The crystal rotation, pot rotation and thermal field temperature are adjusted, the crystal rotation is 5-15r/min, the pot rotation is 2-6r/min, the rotation directions of the crystal rotation and the pot rotation are opposite, and the crystal growth is carried out;

S4: In the seeding stage, after the crystal growth is completed, the power of the induction coil is reduced by 30%-50% compared with the power of the late chemical material, and the temperature is lowered to the seeding temperature at the second rate, and the cooling device is turned off after reaching the seeding temperature. 14. Further by controlling the power of the high-frequency eddy current induction coils of the upper heater 19 and the lower heater 20, the axial and radial temperature field gradients are adjusted, and the temperature field gradient is 1-5 °C/cm; the seed crystal is adjusted to Contact with the upper surface of the melt 6, adjust the crucible to 1-5 r/min and the crystal to 5-20 r/min, start the single crystal pulling, control the crystal pulling speed at 0.4-1 mm/min, and the crucible lowering speed at 0.01-0.1 mm/min, the crystal growth rate is 50-80g/h, and the crystal diameter is 20-40mm;

S5: put the shoulder, adjust the coil power of the upper heater 19 to be 2-10% higher than the coil power of the lower heater 20, so that the shoulder part of the crystal can obtain heat compensation, ensure the uniformity of the temperature at the head and tail of the crystal, and prevent the crystal from cracking; Maintain the pulling speed at 0.6-1.6mm/min, and control the crystal growth speed to gradually increase from 50-80g/h to 500g/h;

S6: Equal diameter growth, maintain the pulling speed at 0.6-1.6mm/min, and control the crystal growth speed at 500-2000g/h;

S7: cooling stage, after reaching the set single crystal length, enter the cooling stage, turn on the cooling device 14, the power of the induction coil is gradually reduced to 0KW, the pulling speed, crystal rotation, and crucible rotation are all reduced to 0, and the temperature is lowered at the third rate;

S8: Finishing stage, after dropping to the third temperature, turn off the cooling device 14, then remove the crucible 5, take out the material as a whole, cut off 20-30mm of the head and tail, melt the remaining material, ingot to obtain 7N germanium; The head and tail materials are returned to the zone melting stage as production raw materials to form a closed-loop cycle of germanium, and there is no waste in the entire purification process.

Preferably, the first temperature is 60-120°C above the melting point of the grown crystal; the second temperature is 0-50°C above the melting point of the grown crystal, the third temperature is 20-50°C, and the first rate is 1-10°C /h; the second rate is 20-50°C/h, and the third rate is 50-100°C/h.

Example 1

With the device of FIG. 1 , the angle between the upper heater 19 and the lower heater 20 is 120°. Both the upper heater 19 and the lower heater 20 are composed of three heating coils connected in series, and the power of a single heating coil is 10-30KW.

The raw material used is 5N germanium after regional smelting, and its product impurity content, ppm, is as follows:

impurities Mg Al Ca Fe Co Ni Cu Zn In Pb content <0.05 <0.05 <0.1 <0.05 <0.02 <0.02 <0.01 <0.05 <0.01 <0.02

(1) 5kg 5N zone melting germanium raw material is placed in the crucible 5, and placed in the single crystal pulling furnace 1; The crucible 5 is evacuated 2 times by using a vacuum equipment, and then filled with nitrogen with 4L/min, keeping a low pressure condition;

(2) Chemical material stage: in the early stage, gradually increase the power of the high-frequency eddy current induction coil for heating until it reaches the maximum power of 30KW. At the same time, turn on the auxiliary heating device 16 to heat the raw material to about 1030°C, and then keep the power of 30KW unchanged. Heating for 30min, then reduce the coil power to about 27KW, melt the raw material in crucible 5, adjust the crucible to 1.5r/min, and keep growing for 2h;

(3) Crystal growth stage: turn off the auxiliary heating device 16 and turn on the cooling device 14 at the same time, the power of the induction coil is reduced to 24KW, and the power of the induction coil is reduced to about 980°C at 8°C/h. /min, the rotation directions of the crystal rotation and the pot rotation are opposite, and the crystal growth is carried out;

(4) Seeding stage: After the crystal growth is completed, the power of the induction coil is reduced to 16KW, and the temperature is lowered to 935°C at 30°C/h, and then the cooling device 14 is closed, and the high frequency of the upper heater 19 and the lower heater 20 is further controlled by controlling the high frequency of the upper heater 19 and the lower heater 20. The power of the eddy current induction coil is 15KW, the axial and radial temperature field gradients are adjusted, the temperature field gradient is 4°C/cm, the seed crystal is adjusted to be in contact with the upper surface of the melt 6, and the adjustment pot is turned to 2.9r/min , crystal rotation 9.4r/min, start single crystal pulling, control crystal pulling speed at 0.8mm/min, crucible lowering speed at 0.08mm/min, crystal growth speed at 65g/h, crystal diameter at 25mm;

(5) Shoulder placement: adjust the coil power of the upper heater to 16.5KW and the coil power of the lower heater to 15KW, maintain the pulling speed at 1.1mm/min, and control the crystal growth rate to gradually increase from 65g/h to 500g/h;

(6) Equal diameter growth: maintain the pulling speed at 1.2mm/min and control the crystal growth speed at 1200g/h;

(7) Cooling stage: After reaching the set single crystal length, enter the cooling stage, turn on the cooling device 14, the power of the induction coil is gradually reduced to 0KW, the pulling speed, crystal rotation and crucible rotation are all reduced to 0, and the temperature is lowered at 70°C/h ;

(8) Finishing stage: when the temperature drops to about 50°C, close the cooling device 14, then remove the crucible 5, take out the material as a whole, cut off 20-30mm of the head and the tail, melt the remaining material, ingot, and obtain 7N germanium; The cut-off head and tail material are returned to the zone melting stage as production raw materials.

The prepared crystal has good crystallinity, and the crystal has no defects such as cracking, dislocation, bubble, inclusion and scattering. The analysis and test results of 7N germanium products are as follows.

7N germanium product analysis and test results (ppb)

Example 2

With the device of FIG. 1 , the angle between the upper heater 19 and the lower heater 20 is 120°. Both the upper heater 19 and the lower heater 20 are composed of three heating coils connected in series, and the power of a single heating coil is 10-30KW.

The raw material used is 5N germanium after regional smelting, and its product impurity content, ppm, is as follows:

impurities Mg Al Ca Fe Co Ni Cu Zn In Pb content <0.03 <0.05 <0.1 <0.03 <0.02 <0.02 <0.02 <0.05 <0.01 <0.02

(1) 5kg 5N zone melting germanium raw material is placed in the crucible 5, and placed in the single crystal pulling furnace 1; The crucible 5 is evacuated 2 times by using a vacuum device, and then filled with nitrogen with 5L/min, keeping a low pressure condition;

(2) Material chemical stage: in the early stage, gradually increase the power of the high-frequency eddy current induction coil for heating until the maximum power is 30KW, and at the same time turn on the auxiliary heating device 16 to heat the raw material to about 1050°C, and then keep the power of 30KW unchanged. Heating for 30min, then reduce the coil power to about 27KW, melt the raw material in crucible 5, adjust the crucible to 1.8r/min, and keep the growth for 2h;

(3) Crystal growth stage: turn off the auxiliary heating device 16 and turn on the cooling device 14 at the same time, the power of the induction coil is reduced to 24KW, and is reduced to about 970°C at 8°C/h, the crystal rotation is adjusted to 8.5r/min, and the pot is turned to 2.2r/min, the rotation direction of crystal rotation and pot rotation are opposite, and the crystal growth is carried out;

(4) Seeding stage: After the crystal growth is completed, the power of the induction coil is reduced to 17KW, and the temperature is lowered to 930°C at 35°C/h, and then the cooling device 14 is closed, and the high frequency of the upper heater 19 and the lower heater 20 is further controlled by controlling the high frequency of the upper heater 19 and the lower heater 20. The power of the eddy current induction coil is 15KW, the axial and radial temperature field gradients are adjusted, the temperature field gradient is 4°C/cm, the seed crystal is adjusted to be in contact with the upper surface of the melt 6, and the adjustment pot is turned to 2.9r/min , Crystal rotation 9.4r/min, start single crystal pulling, control crystal pulling speed at 0.85mm/min, crucible lowering speed at 0.084mm/min, crystal growth speed at 70g/h, crystal diameter at 25mm;

(5) Shoulder release: adjust the coil power of the upper heater to 16.5KW and the coil power of the lower heater to 15KW, maintain the pulling speed at 1.2mm/min, and control the crystal growth rate to gradually increase from 70g/h to 500g/h;

(6) Equal diameter growth: maintain the pulling speed at 1.25mm/min and control the crystal growth speed at 1200g/h;

(7) Cooling stage: After reaching the set single crystal length, enter the cooling stage, turn on the cooling device 14, the power of the induction coil is gradually reduced to 0KW, the pulling speed, crystal rotation and crucible rotation are all reduced to 0, and the temperature is lowered at 65°C/h ;

(8) Finishing stage: when the temperature drops to about 50°C, close the cooling device 14, then remove the crucible 5, take out the material as a whole, cut off 20-30mm of the head and the tail, melt the remaining material, ingot, and obtain 7N germanium; The cut-off head and tail material are returned to the zone melting stage as production raw materials.

The prepared crystal has good crystallinity, and the crystal has no defects such as cracking, dislocation, bubble, inclusion and scattering. The analysis and test results of 7N germanium products are as follows.

7N germanium product analysis and test results (ppb)

The above are only preferred embodiments of the present invention, and do not limit the present invention in any form. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention should fall within the protection scope of the technical solutions of the present invention.

Claims (7)

1. A device for preparing high-purity single crystal germanium by a pulling method comprises a germanium single crystal growth furnace with a crucible arranged in a cavity, and is characterized in that a heating device is arranged around the crucible, the cross section of the heating device in the single crystal pulling direction is of a symmetrical structure in a shape of' and surrounds the crucible in the middle, the heating device is divided into an upper heater and a lower heater, the included angle between the upper heater and the lower heater is 110-160 degrees, and a plurality of high-frequency eddy current induction coils which are uniformly distributed from top to bottom are arranged in the upper heater and the lower heater so as to control the axial gradient and the radial gradient of a temperature field around the single crystal.

2. The apparatus of claim 1, wherein the upper and lower heaters are each comprised of at least three high frequency eddy current induction coils connected in series.

3. The apparatus for preparing single crystal germanium by the pulling method according to claim 1 or 2, wherein the crucible is made of iridium metal.

4. The apparatus for producing single crystal germanium according to claim 1 or 2, wherein the furnace wall of the germanium single crystal growth furnace is composed of a heat-retaining cover, the heating means is disposed in the heat-retaining cover, the heat-retaining cover comprises a first heat-retaining cover and a second heat-retaining cover, the first heat-retaining cover laterally surrounds the heating means, the second heat-retaining cover laterally surrounds the crucible and the heating means from the bottom and the top, and laterally surrounds the first heat-retaining cover.

5. The device for preparing high-purity single crystal germanium according to the pulling method of claim 1 or 2, wherein the crucible lowering mechanism is arranged at the bottom of the crucible and comprises a support column and a crucible lowering driving device, the upper end of the support column is connected to the bottom of the crucible, the lower end of the support column is connected to the crucible lowering driving device, and the support column can be lifted up and down and rotated under the driving of the crucible lowering driving device.

6. The apparatus of claim 5, wherein the support column comprises a cooling device disposed at the center of the support column along the axial direction, and the upper end of the cooling device is in contact with the center of the crucible.

7. The apparatus of claim 6, wherein the support column further comprises an auxiliary heating unit disposed at the periphery of the cooling unit, the upper end of the auxiliary heating unit contacts the bottom of the crucible, a first thermal insulation layer is disposed between the cooling unit and the auxiliary heating unit to separate the cooling unit and the auxiliary heating unit, and a second thermal insulation layer is disposed at the periphery of the auxiliary heating unit to form the outermost layer of the support column.

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