CN114574950A - Method for pulling low-dislocation ultra-high-purity germanium single crystal - Google Patents
Method for pulling low-dislocation ultra-high-purity germanium single crystal Download PDFInfo
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- CN114574950A CN114574950A CN202210277220.3A CN202210277220A CN114574950A CN 114574950 A CN114574950 A CN 114574950A CN 202210277220 A CN202210277220 A CN 202210277220A CN 114574950 A CN114574950 A CN 114574950A
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- 239000013078 crystal Substances 0.000 title claims abstract description 226
- 238000000034 method Methods 0.000 title claims abstract description 68
- 229910052732 germanium Inorganic materials 0.000 title claims abstract description 61
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 title claims abstract description 61
- 238000001816 cooling Methods 0.000 claims abstract description 57
- 238000010899 nucleation Methods 0.000 claims abstract description 21
- 239000002994 raw material Substances 0.000 claims description 30
- 239000000463 material Substances 0.000 claims description 29
- 230000009467 reduction Effects 0.000 claims description 20
- 238000010438 heat treatment Methods 0.000 claims description 19
- 239000000155 melt Substances 0.000 claims description 18
- 238000002844 melting Methods 0.000 claims description 13
- 230000008018 melting Effects 0.000 claims description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- 239000001257 hydrogen Substances 0.000 claims description 11
- 229910052739 hydrogen Inorganic materials 0.000 claims description 11
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 10
- 238000004140 cleaning Methods 0.000 claims description 6
- 230000007797 corrosion Effects 0.000 claims description 6
- 238000005260 corrosion Methods 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 238000005498 polishing Methods 0.000 claims description 6
- 238000007789 sealing Methods 0.000 claims description 6
- 238000007664 blowing Methods 0.000 claims description 5
- 238000000227 grinding Methods 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 4
- 238000011068 loading method Methods 0.000 claims description 3
- 239000000289 melt material Substances 0.000 claims 2
- 230000008569 process Effects 0.000 abstract description 29
- 230000007547 defect Effects 0.000 abstract description 8
- 230000001788 irregular Effects 0.000 abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 238000005406 washing Methods 0.000 description 9
- 239000007788 liquid Substances 0.000 description 7
- 239000010453 quartz Substances 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- 238000010926 purge Methods 0.000 description 3
- 238000009991 scouring Methods 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 238000004781 supercooling Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012768 molten material Substances 0.000 description 1
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- 230000003071 parasitic effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000005433 particle physics related processes and functions Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
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- 238000000746 purification Methods 0.000 description 1
- 238000010408 sweeping Methods 0.000 description 1
- 238000004857 zone melting Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
- C30B15/20—Controlling or regulating
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
- C30B15/20—Controlling or regulating
- C30B15/22—Stabilisation or shape controlling of the molten zone near the pulled crystal; Controlling the section of the crystal
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/02—Elements
- C30B29/08—Germanium
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
The invention discloses a pulling method of a low dislocation ultrahigh pure germanium single crystal, which comprises the following steps: melt, seeding, necking down, shouldering, constant diameter, ending and cooling, shouldering with still include the following step between the constant diameter: and (2) shouldering: reducing the crystal rotation speed and the crucible rotation speed, uniformly increasing the pulling speed, controlling uniform cooling according to the low cooling frequency and keeping for a certain time, so that the crystal diameter gradually grows to the crystal size required by the equal diameter. In the scheme, the pulling speed is uniformly increased by uniformly reducing the crystal rotating speed and the crucible rotating speed; and then reducing the frequency and uniformly cooling to ensure that the diameter of the crystal gradually grows to the size of the crystal required by the equal diameter, namely the crystal is convenient to link the shouldering process and the equal diameter process, so that the crystal can inhibit the inversion process of an interface under the condition, the crystal diameter is prevented from becoming thin after shouldering, the crystal becomes irregular, and the crystal is prevented from generating defects.
Description
Technical Field
The invention relates to the technical field of cz method single crystal growth, in particular to a method for pulling a low-dislocation ultra-high-purity germanium single crystal.
Background
The basic principle of single crystal growth by the Claus-based method (hereinafter referred to as cz method) is that a raw material for crystal growth is placed in a crucible and heated to melt, and a certain degree of supercooling is generated in the melt, so that a nucleation driving force is generated. And (2) immersing seed crystals fixed at the lower end of the seed crystal rod into the upper surface of the melt, after one end of the seed crystals immersed into the melt is partially melted, lifting the seed crystal rod upwards at a certain speed, and transmitting heat generated at a solid-liquid interface in the crystallization process through the seed crystal rod. The melt in contact with the seed crystal first acquires a certain degree of supercooling and begins the crystallization process. With the slow pulling of the seed rod, the continuous crystal growth can be realized by controlling factors such as temperature, pulling speed and the like. The growth dynamics of the crystal can be observed at any time by pulling the single crystal by the CZ method, the growth condition of the crystal is convenient to master, and the growth condition is easy to control; in the process of crystal growth, the crystal is not contacted with the crucible wall, so that the parasitic nucleation generated by the crystal and the crucible wall can be obviously reduced. In addition, the crystal grown by the pulling method has high integrity, high growth rate and large crystal size, and can grow a crystal with a specific crystal orientation according to the crystal orientation of the seed crystal, so the crystal is widely applied to the field of single crystal growth.
The high-purity germanium detector plays an increasingly important role in the high-tech field, and is widely applied to experimental research of nuclear physics, particle physics and celestial physics. The method has the advantages of good energy resolution, high detection efficiency, strong stability and the like in the aspect of detecting particles, particularly X and gamma rays, and is beyond the reach of other gamma detectors. The pure impurity concentration of the high-purity germanium single crystal material of the detector grade must be less than 2 x 1010cm-3The dislocation density must reach 500-2In order to obtain the high-purity low-dislocation high-purity germanium single crystal, electronic grade germanium (5N-6N) is used as a raw material, a special zone melting purification method is adopted to obtain a detector grade germanium polycrystalline material, and a special single crystal pulling method is adopted to obtain a large-volume low-dislocation high-purity germanium single crystal material.
Generally, the solid-liquid interface in the single crystal pulling process is mainly a slightly convex interface, but as the crystal diameter increases, or the rotation speed increases, the interface will become convex and flat due to interface inversion caused by interface meltback, which is often a sudden change process, which results in a sudden increase in melt temperature, rapid thinning of crystal diameter, and crystal irregularities, and which also tend to cause defects in the crystal.
Disclosure of Invention
In view of the above, the invention provides a method for pulling a low-dislocation ultra-high purity germanium single crystal, which uniformly reduces the crystal rotation speed and the crucible rotation speed and uniformly increases the pulling speed; and then reducing the frequency and uniformly cooling to ensure that the diameter of the crystal gradually grows to the size of the crystal required by the equal diameter, namely the crystal is convenient to link the shouldering process and the equal diameter process, so that the crystal can inhibit the inversion process of an interface under the condition, the crystal diameter is prevented from becoming thin after shouldering, the crystal becomes irregular, and the crystal is prevented from generating defects.
In order to achieve the purpose, the invention provides the following technical scheme:
a method for pulling a low-dislocation ultra-high purity germanium single crystal, comprising the steps of: melt, seeding, necking down, shouldering, constant diameter, ending and cooling, shouldering with still include the following step between the constant diameter:
and (2) shouldering: reducing the crystal rotation speed and the crucible rotation speed, uniformly increasing the pulling speed, controlling uniform cooling according to the low cooling frequency and keeping for a certain time, so that the crystal diameter gradually grows to the crystal size required by the equal diameter.
Preferably, the shouldering step two comprises:
reducing the crystal rotation speed to 3-5r/min, reducing the crucible rotation speed to 3-5r/min, uniformly increasing the pulling speed to 30-40mm/h, controlling uniform cooling according to the cooling frequency of 80-120w/h, keeping for a certain time, enabling the crystal diameter to gradually grow to the crystal size required by the equal diameter, and stopping cooling.
Preferably, the frit includes:
grinding raw materials: polishing and cleaning a germanium ingot raw material;
raw material corrosion: corroding and cleaning a germanium ingot raw material, and drying by adopting nitrogen;
charging: loading a germanium ingot raw material and high-purity seed crystals into a pulling furnace, sealing the pulling furnace and introducing hydrogen for blowing;
material melting: controlling the heating power to raise the temperature to 1000 ℃ and keeping the temperature constant, so that the germanium ingot raw material is completely melted.
Preferably, the melting material further comprises, between the charging furnace and the melting material:
preheating: starting the crystal rotation speed of 5-10r/min and the crucible rotation speed of 5-10r/min, controlling the heating power to raise the temperature to 400-;
the material melting comprises the following steps:
controlling the heating power to raise the temperature to 400-.
Preferably, the seeding comprises:
slowly inserting high-purity seed crystals into the melt, adjusting heating power according to the melt interface, waiting for 10-20min to start seeding after an aperture with a certain width appears, gradually increasing the pulling speed to 20-30mm/h, keeping the pulling speed for seeding for 10-30min, and controlling the diameter of the crystals to be 5-10mm stably.
Preferably, the necking comprises:
uniformly increasing the pulling speed by 10-20mm/h at intervals of 10min to increase the pulling speed to 90-150mm/h, and controlling the diameter of the crystal to be stabilized at 3-5 mm.
Preferably, the method further comprises the following steps between the necking and the shouldering:
thin neck: keeping the drawing speed at 90-150mm/h, and drawing a thin neck with the length of 90-150 mm.
Preferably, the shouldering comprises:
opening the crucible to raise the speed by 0.8-1mm/h, and uniformly reducing the pulling speed to 20-30 mm/h;
controlling uniform temperature reduction and keeping for a certain time to ensure that the crystal diameter gradually grows to the required crystal size.
Preferably, the ending comprises:
and (4) reducing the crucible raising speed to 0.3-0.8mm/h, controlling uniform cooling and keeping for a certain time till the melt is completely pulled.
Preferably, the cooling comprises:
closing crystal lifting and crucible lifting, and cooling in three stages until the temperature is reduced to room temperature; wherein, the temperature reduction frequency of the three stages is higher backwards;
and closing the crystal rotation and the crucible rotation to finish crystal pulling.
According to the technical scheme, the pulling speed is uniformly increased by uniformly reducing the crystal rotating speed and the crucible rotating speed; and then reducing the frequency and uniformly cooling to ensure that the diameter of the crystal gradually grows to the size of the crystal required by the equal diameter, namely the crystal is convenient to link the shouldering process and the equal diameter process, so that the crystal can inhibit the inversion process of an interface under the condition, the crystal diameter is prevented from becoming thin after shouldering, the crystal becomes irregular, and the crystal is prevented from generating defects.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow chart of a method for pulling a low dislocation ultra-high purity germanium single crystal according to an embodiment of the present invention;
FIG. 2 is a dislocation diagram of an embodiment of the present invention;
FIG. 3 is a dislocation diagram of a comparative example provided by an embodiment of the present invention;
fig. 4 is a diagram of a third dislocation of a comparative example provided by an example of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The method for pulling the low-dislocation ultra-high purity germanium single crystal provided by the embodiment of the invention, as shown in fig. 1, comprises the following steps: melt, seeding, necking down, shouldering, constant diameter, ending and cooling put the shoulder with still include following step between the constant diameter:
and (2) shouldering: reducing the crystal rotation speed and the crucible rotation speed, uniformly increasing the pulling speed, controlling uniform cooling according to the low cooling frequency and keeping for a certain time, so that the crystal diameter gradually grows to the crystal size required by the equal diameter.
It should be noted that, the scheme uniformly reduces the crystal rotation speed and the crucible rotation speed, and uniformly increases the pulling speed; and then uniformly cooling the crystal according to the low cooling frequency and keeping the crystal for a certain time to ensure that the diameter of the crystal gradually grows to the size of the crystal required by the equal diameter, namely the process of putting the crystal on shoulder is linked with the process of the equal diameter. Wherein, the temperature reduction frequency of the shouldering stage is lower than that of the shouldering stage, and the details can be seen in the following description.
According to the technical scheme, in the pulling method of the low-dislocation ultrahigh-purity germanium single crystal, the pulling speed is uniformly increased by uniformly reducing the crystal rotating speed and the crucible rotating speed; and then reducing the frequency and uniformly cooling to ensure that the diameter of the crystal gradually grows to the size of the crystal required by the equal diameter, namely the crystal is convenient to link the shouldering process and the equal diameter process, so that the crystal can inhibit the inversion process of an interface under the condition, the crystal diameter is prevented from becoming thin after shouldering, the crystal becomes irregular, and the crystal is prevented from generating defects.
Specifically, the shouldering step two includes:
reducing the crystal rotation speed to 3-5r/min, reducing the crucible rotation speed to 3-5r/min, uniformly increasing the pulling speed to 30-40mm/h, controlling uniform cooling according to the cooling frequency of 80-120w/h, keeping for a certain time, enabling the crystal diameter to gradually grow to the crystal size required by the equal diameter, and stopping cooling. The second design of the scheme is designed so that the crystal can better inhibit the inversion process of the interface under the condition, and the defects caused by pulling the crystal are further avoided. Of course, when pulling a three inch single crystal, the temperature can be stopped by stepping down for 1-2 hours at this stage so that the crystal diameter is stably maintained at 70-80 mm.
Further, the frit includes:
grinding raw materials: polishing and cleaning a germanium ingot raw material; preparing 6-8kg of germanium ingot raw material with the carrier concentration less than or equal to 8e10, polishing the germanium ingot raw material by using scouring pad, removing concave-convex burrs on the surface of the raw material until the surface is smooth, and washing the raw material by pure water;
raw material corrosion: corroding and cleaning a germanium ingot raw material, and drying by adopting nitrogen; wherein, germanium material is placed in HNO3: HF ═ 2-3): 1, taking out the material after the surface is bright after corrosion in the corrosive liquid, washing the material for more than 20min by pure water, and blowing the germanium material by using high-purity nitrogen when the conductivity of the washing liquid is measured to be close to 0.1-0.15;
charging: loading a germanium ingot raw material and high-purity seed crystals into a pulling furnace, sealing the pulling furnace and introducing hydrogen for blowing and sweeping; preparing high-purity seed crystals, fixing the seed crystals on a seed crystal chuck below a seed crystal rod, knocking a germanium material into small blocks, putting the small blocks into a quartz crucible, sealing a pulling furnace, vacuumizing to below 1pa, and then introducing high-purity hydrogen to purge for more than 3 hours;
material melting: controlling the heating power to raise the temperature to 1000 ℃ and keeping the temperature constant, so that the germanium ingot raw material is completely melted.
Still further, the molten material still includes between the charging furnace and the melting material:
preheating: starting the crystal rotation speed of 5-10r/min and the crucible rotation speed of 5-10r/min, controlling the heating power to raise the temperature to 400-; wherein, the hydrogen flow is set to be 2-5L/min, the heating power is controlled to be 40-60min, the temperature is raised to 400-450 ℃, and the preheating is carried out for 2-5 h; that is to say, the scheme adds a preheating stage before melting the material so as to eliminate the influence of adverse factors such as water, oxygen and the like on the pulling of the single crystal;
the material melting comprises the following steps:
controlling the heating power to raise the temperature to 400-. Wherein the heating power is controlled to raise the temperature of 400-.
In this aspect, the seeding includes:
slowly inserting high-purity seed crystals into the melt, adjusting heating power according to the melt interface, waiting for 10-20min to start seeding after an aperture with a certain width appears, gradually increasing the pulling speed to 20-30mm/h, keeping the pulling speed for seeding for 10-30min, and controlling the diameter of the crystals to be 5-10mm stably.
Specifically, the necking comprises:
uniformly increasing the pulling speed by 10-20mm/h at an interval of 10min to increase the pulling speed to 90-150mm/h, and controlling the diameter of the crystal to be stabilized at 3-5 mm. Wherein the pull rate can be increased manually. The scheme is designed so as to facilitate the quick necking of the crystal.
Further, as shown in fig. 1, the method further includes the following steps between the necking and the shouldering:
thin neck: keeping the drawing speed at 90-150mm/h, and drawing a thin neck with the length of 90-150 mm. That is, the scheme keeps a high pulling speed of 90-150mm/h to continuously pull a section of 90-150mm thin neck on the basis that the diameter of the neck is 3-5mm, so that most of dislocation is discharged under the condition, but the dislocation is controlled not to be completely discharged, thereby being beneficial to realizing low dislocation of the single crystal.
Still further, the shouldering comprises:
opening the crucible to raise the speed by 0.8-1mm/h, and uniformly reducing the pulling speed to 20-30 mm/h; wherein, the frequency of reducing the pulling speed in the stage is as follows: uniformly reducing the pulling speed by 20-40mm/h at intervals of 10 min;
controlling uniform temperature reduction and keeping for a certain time to ensure that the crystal diameter gradually grows to the required crystal size. Wherein, in the shoulder-setting stage, the uniform temperature reduction is controlled according to the high temperature reduction frequency of 120-180 w/h. That is to say, the shouldering stage is controlled in two stages, namely, the pulling speed is uniformly reduced, and the temperature is uniformly reduced, namely, the kinetic energy is controlled firstly and then the heat energy is controlled, so that the uniform shouldering can not generate new dislocation under the condition, and the low dislocation of the single crystal can be further realized. Of course, when pulling a three inch single crystal, the shoulder may be set for 1-2 hours at this stage, allowing the crystal diameter to grow gradually to 50-65 mm.
In order to further optimize the above technical solution, the ending includes:
and (4) reducing the crucible raising speed to 0.3-0.8mm/h, controlling uniform cooling and keeping for a certain time till the melt is completely pulled. Wherein the temperature reduction frequency of the ending stage is 100-200 w/h.
Specifically, the cooling includes:
closing crystal lifting and crucible lifting, and cooling in three stages until the temperature is reduced to room temperature; wherein, the temperature reduction frequency of the three stages is higher; wherein, this scheme will cool down and divide into three stages and go on: in the first stage, the temperature is uniformly reduced for 1h according to the temperature reduction frequency of 300-400 w/h; in the second stage, the temperature is uniformly reduced for 2 hours according to the temperature reduction frequency of 500-600 w/h; in the third stage, the temperature is uniformly reduced at the temperature reduction frequency of 800-; that is to say, in the scheme, the cooling frequency is lower at the stage of higher temperature, so that a uniform cooling mode that the cooling is slow firstly and then fast is realized, the phenomenon that the crystal generates dislocation due to too fast temperature change is prevented, and the low dislocation of the single crystal is further realized;
and closing the crystal rotation and the crucible rotation to finish crystal pulling.
The present solution is further described below with reference to specific embodiments:
the method for pulling the low-dislocation ultra-high purity germanium single crystal provided by the embodiment of the invention (taking pulling of a germanium single crystal with a diameter of three inches as an example for explanation), comprises the following steps:
first, prepare (i.e. the above melt step, the same below)
a. Grinding raw materials: preparing 6-8kg of germanium ingot raw material with the carrier concentration less than or equal to 8e10, polishing by using scouring pad, removing concave-convex burrs on the surface of the raw material until the surface is smooth, and washing by pure water;
b. and (3) corrosion: placing germanium material in HNO3: HF ═ 2-3): 1, taking out the water after the water is corroded to be bright on the surface, washing the water for more than 20min by pure water, and measuring that the conductivity of the washing liquid is close to 01-0.15, blowing the germanium material by using high-purity nitrogen;
c. charging: preparing high-purity seed crystals, fixing the seed crystals on a seed crystal chuck below a seed crystal rod, knocking a germanium material into small blocks, putting the small blocks into a quartz crucible, sealing a pulling furnace, vacuumizing to below 1pa, and introducing high-purity hydrogen to purge for more than 3 hours;
d. preheating: setting hydrogen flow at 2-5L/min, starting crystal rotation at 5-10r/min, starting crucible rotation at 5-10r/min, controlling power, heating to 400-450 ℃ in 40-60min, and preheating for 2-5 h;
e. material melting: controlling the power within 2-4h, heating to 1000 ℃, keeping the temperature constant, cooling to 940-;
secondly, seeding
Slowly inserting a seed crystal into the melt, adjusting power according to the melt interface, waiting for 10-20min after an aperture with a certain width appears, and starting seeding: gradually increasing the pulling speed to 20-30mm/h, maintaining the pulling speed for seeding for 10-30min, and controlling the diameter of the crystal to be stabilized at 5-10mm as a standard;
third, necking down
Manually increasing the pulling speed, uniformly increasing the pulling speed by 10-20mm/h at an interval of 10min until the pulling speed is increased to 90-150mm/h, and controlling the diameter of the crystal to be stabilized at 3-5mm as a standard;
four, thin neck
Keeping the drawing speed at 90-150mm/h, and drawing the thin neck at the high drawing speed, wherein the drawing length at this stage is 90-150 mm;
fifthly, shoulder-putting one (namely the shoulder-putting step above, the same below)
Opening the crucible to lift: 0.8-1 mm/h; uniformly reducing the pulling rate to 20-30mm/h, wherein the frequency of reducing the pulling rate is as follows: uniformly reducing the pulling speed by 20-40mm/h at intervals of 10 min;
controlling the power to uniformly cool, wherein the cooling frequency is 180w/h and the shouldering time is 1-2h, and the diameter of the crystal gradually grows to 50-65 mm;
sixthly, put on shoulder two
Controlling power to uniformly cool, reducing crystal rotation to 3-5r/min, reducing crucible rotation to 3-5r/min, and uniformly raising pulling speed to 30-40 mm/h; the temperature reduction frequency is 80-120w/h, the shouldering is continued for 1-2h, and the diameter of the crystal is kept stable; stopping cooling when the thickness is 70-80 mm;
seven, equal diameter
Uniformly recovering the pulling speed to 20-30mm/h, observing the diameter of the crystal, and manually controlling the power to keep the diameter of the crystal at 70-80mm, wherein the diameter process is equal for 4-6 h;
eighth, ending
Lowering the crucible to 0.3-0.8mm/h, controlling the power to uniformly cool, wherein the cooling frequency is 100-200w/h, and the end is 2-3h until the melt in the quartz crucible is completely drawn;
ninth, cooling
Closing crystal liter and crucible liter, controlling power to cool to room temperature, and cooling in three stages: the first stage is 300-400w/h, and the temperature is reduced for 1 h; the second stage is 500-600w/h, and the temperature is reduced for 2 h; the third stage is 800-;
and closing the crystal rotation and crucible rotation to finish crystal pulling.
Example (b):
pulling a three inch diameter germanium single crystal comprising:
first, prepare (i.e. the above melt step, the same below)
a. Grinding raw materials: preparing 7kg of germanium ingot raw material with the carrier concentration less than or equal to 8e10, polishing by using scouring pad, removing concave-convex burrs on the surface of the raw material until the surface is smooth, and washing by pure water;
b. and (3) corrosion: placing germanium material in HNO3: HF ═ 2.5: 1, taking out the silicon wafer after the silicon wafer is corroded to be bright in surface, washing the silicon wafer for more than 20min by pure water, and drying the germanium material by using high-purity nitrogen when the conductivity of the washing liquid is measured to be close to 0.12;
c. charging: preparing high-purity seed crystals, fixing the seed crystals on a seed crystal chuck below a seed crystal rod, knocking a germanium material into small blocks, putting the small blocks into a quartz crucible, sealing a pulling furnace, vacuumizing to below 1pa, and introducing high-purity hydrogen to purge for 3 hours;
d. preheating: setting the hydrogen flow at 4L/min, starting crystal rotation at 7r/min, starting crucible rotation at 7r/min, controlling power, heating to 400-430 ℃ within 50min, and preheating for 4 h;
e. material melting: controlling the power within 3h, heating to 1000 ℃, keeping the temperature constant, cooling to 950 ℃ after the germanium material is completely melted, and keeping the temperature constant for 45 min;
secondly, seeding
Slowly inserting a seed crystal into the melt, adjusting power according to the melt interface, waiting for 15min after an aperture with a certain width appears, and starting seeding: gradually increasing the pulling speed to 24mm/h, keeping the pulling speed for seeding for 15min, and controlling the diameter of the crystal to be stabilized at 6mm as a standard;
third, necking down
Manually increasing the pulling speed, uniformly increasing the pulling speed by 15mm/h at intervals of 10min until the pulling speed is increased to 100mm/h, and controlling the diameter of the crystal to be stabilized at 4mm as a standard;
four, thin neck
Keeping the drawing speed at 100mm/h, and drawing the thin neck at the high drawing speed, wherein the drawing length is 120mm at the stage;
fifthly, shouldering one (namely the shouldering step, the same below)
Opening the crucible to lift: 0.9 mm/h; uniformly reducing the pulling speed to 24mm/h, wherein the frequency of reducing the pulling speed is as follows: uniformly reducing the pulling speed by 30mm/h at intervals of 10 min;
controlling the power to uniformly cool, wherein the cooling frequency is 150w/h, the shouldering time is 1.5h, and the diameter of the crystal gradually grows to 60 mm;
sixthly, put on shoulder two
Controlling power to uniformly cool, reducing crystal rotation to 4r/min, reducing crucible rotation to 4r/min, and uniformly raising pulling speed to 32 mm/h; the temperature reduction frequency is 100w/h, the shouldering is continued for 1.5h, and the temperature reduction is stopped when the diameter of the crystal is stably kept at 78 mm;
seven, equal diameter
Uniformly recovering the pulling speed to 24mm/h, observing the diameter of the crystal, manually controlling the power to keep the diameter of the crystal at 78mm, and performing an isodiametric process for 5 h;
eighth, ending
Lowering the crucible to 0.5mm/h, controlling the power to uniformly cool, wherein the cooling frequency is 110w/h, and the end is 2.5h until the molten liquid in the quartz crucible is completely drawn;
ninth, cooling
Closing crystal liter and crucible liter, controlling power to cool to room temperature, and cooling in three stages: in the first stage, 350w/h and 1h of cooling are carried out; the second stage is 550w/h, and the temperature is reduced for 2 h; in the third stage, 900w/h is carried out, and the temperature is reduced for 5-7h to room temperature;
and closing the crystal rotation and crucible rotation to finish crystal pulling.
Comparative example one:
3-inch germanium single crystal is pulled up completely according to the method and parameters of the embodiment, but a thin neck procedure is not arranged, namely, the thin neck is directly shouldered after being reduced;
comparative example two:
a 3 inch germanium single crystal was pulled up exactly according to the example methods and parameters, but with a neck length of 60 mm;
comparative example three:
a 3 inch germanium single crystal was pulled up exactly according to the example methods and parameters, but with a neck length of 180 mm;
comparative example four:
3 inches of germanium single crystal is pulled up completely according to the method and parameters of the embodiment, and the length of the thin neck is still set to be 120 mm; but the drawing speed of the thin neck is 24mm/h, namely the thin neck process is carried out at a low drawing speed;
comparative example five:
pulling a 3-inch germanium single crystal completely according to the method and parameters of the embodiment, but not setting a shouldering step II, namely, carrying out the whole shouldering process according to the shouldering step I method and parameters;
the high-purity germanium single crystals finally obtained in the examples and the comparative examples are respectively sampled at the equal diameter position and the position 6cm below the equal diameter position, sliced, the dislocation density of the two sample points is respectively detected, the crystal diameters of the positions 6cm below the equal diameter position are respectively counted, and the results are shown in the following table:
further, an example dislocation pattern can be seen in fig. 2, a comparative example first dislocation pattern (dislocation density 18000) can be seen in fig. 3, and a comparative example third dislocation pattern (dislocation density 0) can be seen in fig. 4.
As can be seen from the results of the above table and FIGS. 2, 3 and 4, in the pulling method of the low dislocation ultra-high purity germanium single crystal provided by the invention, the pulling speed is uniformly increased by uniformly reducing the crystal rotating speed and the crucible rotating speed; then reducing the frequency and uniformly cooling to ensure that the crystal diameter is gradually reducedThe crystal size required by the constant diameter is gradually increased, namely the crystal is convenient to connect the shoulder-off process and the constant diameter process, the crystal can inhibit the reverse process of the interface under the condition, the crystal diameter is prevented from being thinned after shoulder-off, the crystal becomes irregular, the crystal is prevented from generating defects, and meanwhile, the dislocation density of the crystal is controlled by controlling the neck diameter, the neck pulling speed, the neck length and other factors, so that most of dislocations are discharged under the condition, but the dislocations are not completely discharged, and the dislocation density of the crystal reaches 500 plus materials 5000/cm2Thereby contributing to low dislocation of the single crystal.
Key points and protection points of the invention:
preparation of
Preheating: setting hydrogen flow at 2-5L/min, starting crystal rotation at 5-10r/min, starting crucible rotation at 5-10r/min, controlling power, heating to 400-450 ℃ within 40-60min, and preheating for 2-5 h;
necking down
Manually increasing the pulling speed, uniformly increasing the pulling speed by 10-20mm/h at intervals of 10min until the pulling speed is increased to 90-150mm/h, and controlling the diameter of the crystal to be stabilized at 3-5mm as a standard;
thin neck
Keeping the drawing speed at 90-150mm/h, and drawing the thin neck at the high drawing speed, wherein the drawing length at the stage is 90-150 mm;
put on shoulder one
Opening the crucible to lift: 0.8-1 mm/h; uniformly reducing the pulling speed to 20-30mm/h, wherein the frequency of reducing the pulling speed is as follows: uniformly reducing the pulling speed by 20-40mm/h at intervals of 10 min;
controlling the power to uniformly cool, wherein the cooling frequency is 180w/h and the shouldering time is 1-2h, and the diameter of the crystal gradually grows to 50-65 mm;
put on shoulder two
Controlling power to uniformly cool, reducing crystal rotation to 3-5r/min, reducing crucible rotation to 3-5r/min, and uniformly raising pulling speed to 30-40 mm/h; the temperature reduction frequency is 80-120w/h, the shouldering is continued for 1-2h, and the diameter of the crystal is kept stable; stopping cooling when the thickness is 70-80 mm;
temperature reduction
The temperature reduction is divided into three stages: the first stage is 300-400w/h, and the temperature is reduced for 1 h; the second stage is 500-600w/h, and the temperature is reduced for 2 h; the first stage 800-.
The invention has the beneficial effects that:
1. adding a preheating stage before material melting: under the atmosphere of high-purity flowing hydrogen, the temperature is raised to 400-450 ℃, and the single crystal is preheated for 2-5h, so that the influence of adverse factors such as water, oxygen and the like on the single crystal pulling is eliminated;
2. the diameter of the neck is 3-5mm, a section of 90-150mm thin neck is pulled out at a high pulling speed of 90-150mm/h, most of dislocations are discharged under the condition, but the dislocations are controlled not to be completely discharged, so that the single crystal dislocations reach 500-5000/cm-2；
3. Shouldering is carried out in two steps, wherein the first step is divided into two stages, namely, the pulling speed is uniformly reduced, the temperature is uniformly reduced, kinetic energy is controlled first, then heat energy is controlled, and new dislocation cannot be generated when shouldering is uniformly carried out under the condition; secondly, uniformly reducing crystal rotation and crucible rotation, and uniformly increasing the pulling speed; then reducing the frequency and uniformly cooling to ensure that the processes of shouldering the crystal and equalizing the diameter are linked; the crystal can inhibit the inversion process of the interface under the condition, prevent the crystal diameter from being thinned after shouldering, prevent the crystal from becoming irregular and prevent the crystal from generating defects;
4. the temperature reduction is divided into three stages: the first stage is 300-400w/h, and the temperature is reduced for 1 h; the second stage is 500-600w/h, and the temperature is reduced for 2 h; the third stage is 800-1000w/h, and the temperature is reduced for 5-7h until the room temperature is reached; the higher the temperature is, the slower the cooling rate is, the slower the cooling is, the faster the cooling is, and the uniform change is realized, so that the dislocation of the crystal caused by the too fast temperature change is prevented.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A method for pulling a low-dislocation ultra-high purity germanium single crystal, comprising the steps of: melt, seeding, necking down, shouldering, constant diameter, ending and cooling, its characterized in that put the shoulder with still include the following step between the constant diameter:
and (2) shouldering: reducing the crystal rotation speed and the crucible rotation speed, uniformly increasing the pulling speed, controlling uniform cooling according to the low cooling frequency and keeping for a certain time, so that the crystal diameter gradually grows to the crystal size required by the equal diameter.
2. The method of pulling a low dislocation ultra-high purity germanium single crystal as claimed in claim 1, wherein said shouldering two comprises:
reducing the crystal rotation speed to 3-5r/min, reducing the crucible rotation speed to 3-5r/min, uniformly raising the pulling speed to 30-40mm/h, controlling uniform cooling according to the cooling frequency of 80-120w/h and keeping for a certain time, so that the crystal diameter gradually grows to the crystal size required by the equal diameter, and stopping cooling.
3. The method of pulling a low dislocation ultra high purity germanium single crystal as claimed in claim 1, wherein said frit comprises:
grinding raw materials: polishing and cleaning a germanium ingot raw material;
raw material corrosion: corroding and cleaning a germanium ingot raw material, and drying by adopting nitrogen;
charging: loading a germanium ingot raw material and high-purity seed crystals into a pulling furnace, sealing the pulling furnace and introducing hydrogen for blowing;
material melting: controlling the heating power to raise the temperature to 1000 ℃ and keeping the temperature constant, so that the germanium ingot raw material is completely melted.
4. The method of pulling a low dislocation ultra high purity germanium single crystal as claimed in claim 3, wherein said melt material further comprises, between said furnace and said melt material:
preheating: starting the crystal rotation speed of 5-10r/min and the crucible rotation speed of 5-10r/min, controlling the heating power to raise the temperature to 400-450 ℃, and preheating for 2-5 h;
the material melting method comprises the following steps:
controlling the heating power to raise the temperature to 400-.
5. The method of pulling a low dislocation ultra-high purity germanium single crystal as claimed in claim 1, wherein said seeding comprises:
slowly inserting high-purity seed crystals into the melt, adjusting heating power according to the melt interface, waiting for 10-20min to start seeding after an aperture with a certain width appears, gradually increasing the pulling speed to 20-30mm/h, keeping the pulling speed for seeding for 10-30min, and controlling the diameter of the crystals to be 5-10mm stably.
6. The method of pulling a low dislocation ultra high purity germanium single crystal as claimed in claim 5, wherein said necking comprises:
uniformly increasing the pulling speed by 10-20mm/h at intervals of 10min to increase the pulling speed to 90-150mm/h, and controlling the diameter of the crystal to be stabilized at 3-5 mm.
7. The method of pulling a low dislocation ultra high purity germanium single crystal as claimed in claim 6, further comprising the steps of, between said neck and said shoulder:
thin neck: keeping the drawing speed at 90-150mm/h, and drawing a thin neck with the length of 90-150 mm.
8. The method of pulling a low dislocation ultra high purity germanium single crystal as claimed in claim 6, wherein said shouldering comprises:
opening the crucible to raise the speed by 0.8-1mm/h, and uniformly reducing the pulling speed to 20-30 mm/h;
controlling uniform temperature reduction and keeping for a certain time to ensure that the crystal diameter gradually grows to the required crystal size.
9. The method of pulling a low dislocation ultra high purity germanium single crystal as claimed in claim 8, wherein said ending comprises:
and (4) reducing the crucible raising speed to 0.3-0.8mm/h, controlling uniform cooling and keeping for a certain time till the melt is completely pulled.
10. The method of pulling a low dislocation ultra-high purity germanium single crystal as claimed in claim 1, wherein said reducing the temperature comprises:
closing the crystal lifting and the crucible lifting, and cooling in three stages until the temperature is reduced to room temperature; wherein, the temperature reduction frequency of the three stages is higher;
and closing the crystal rotation and the crucible rotation to finish crystal pulling.
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| CN113293430A (en) * | 2021-04-25 | 2021-08-24 | 弘元新材料(包头)有限公司 | Method for secondary shouldering in large-diameter single crystal drawing process |
| CN114045557A (en) * | 2021-10-25 | 2022-02-15 | 安徽光智科技有限公司 | Method and equipment for preparing ultra-high purity germanium single crystal |
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| CN103938270A (en) * | 2014-04-09 | 2014-07-23 | 云南北方驰宏光电有限公司 | Growth method of gallium heavily doped low-dislocation germanium single crystal |
| CN109112625A (en) * | 2018-09-28 | 2019-01-01 | 宁晋晶兴电子材料有限公司 | A kind of monocrystalline silicon speed change shouldering technique |
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Denomination of invention: A pulling method for low dislocation ultra-high purity germanium single crystals Granted publication date: 20230623 Pledgee: Huishang Bank Co.,Ltd. Chuzhou Fenghuang road sub branch Pledgor: Anhui Guangzhi Technology Co.,Ltd. Registration number: Y2024980011102 |
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