CN116732608A - Czochralski silicon production device and production method suitable for continuous feeding - Google Patents
Czochralski silicon production device and production method suitable for continuous feeding Download PDFInfo
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 50
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 50
- 239000010703 silicon Substances 0.000 title claims abstract description 50
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 31
- 239000013078 crystal Substances 0.000 claims abstract description 98
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 44
- 239000007788 liquid Substances 0.000 claims abstract description 43
- 239000010453 quartz Substances 0.000 claims abstract description 43
- 239000004065 semiconductor Substances 0.000 claims abstract description 21
- 229910021421 monocrystalline silicon Inorganic materials 0.000 claims abstract description 17
- 239000012774 insulation material Substances 0.000 claims abstract description 7
- 238000000034 method Methods 0.000 claims description 36
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 20
- 239000000155 melt Substances 0.000 claims description 18
- 230000008569 process Effects 0.000 claims description 17
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 14
- 239000002210 silicon-based material Substances 0.000 claims description 13
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 11
- 238000010899 nucleation Methods 0.000 claims description 11
- 229910052721 tungsten Inorganic materials 0.000 claims description 10
- 239000010937 tungsten Substances 0.000 claims description 10
- 229910052799 carbon Inorganic materials 0.000 claims description 9
- 230000008859 change Effects 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 8
- 239000011248 coating agent Substances 0.000 claims description 8
- 238000000576 coating method Methods 0.000 claims description 8
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 4
- 238000001514 detection method Methods 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 4
- 238000001354 calcination Methods 0.000 claims description 3
- 238000011049 filling Methods 0.000 claims description 3
- 238000001947 vapour-phase growth Methods 0.000 claims description 3
- 239000002131 composite material Substances 0.000 claims description 2
- 239000011810 insulating material Substances 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 abstract description 5
- 238000009826 distribution Methods 0.000 description 11
- 230000007547 defect Effects 0.000 description 10
- 238000010438 heat treatment Methods 0.000 description 10
- 238000004321 preservation Methods 0.000 description 10
- 229920005591 polysilicon Polymers 0.000 description 9
- 239000012535 impurity Substances 0.000 description 6
- 230000006698 induction Effects 0.000 description 6
- 238000009413 insulation Methods 0.000 description 5
- 230000001276 controlling effect Effects 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 235000012431 wafers Nutrition 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 239000006004 Quartz sand Substances 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000005247 gettering Methods 0.000 description 1
- 229910021385 hard carbon Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
- 238000004857 zone melting Methods 0.000 description 1
Classifications
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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
- C30B27/00—Single-crystal growth under a protective fluid
- C30B27/02—Single-crystal growth under a protective fluid by pulling from a melt
-
- 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
- C30B15/10—Crucibles or containers for supporting the melt
- C30B15/12—Double crucible methods
-
- 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
- C30B15/14—Heating of the melt or the crystallised materials
-
- 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
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/02—Elements
- C30B29/06—Silicon
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Liquid Deposition Of Substances Of Which Semiconductor Devices Are Composed (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
The invention discloses a Czochralski silicon production device and a production method suitable for continuous feeding, wherein the production device comprises a quartz crucible, a supporting crucible, a heater, a heat shield, a heat insulation material, a main chamber and an auxiliary chamber, the quartz crucible is a double crucible, and the center of the bottom of the crucible is of a concave structure; the heater includes a side heater and a center heater located within a concave configuration at the center of the bottom of the crucible. According to the Yu Zhila monocrystalline silicon production device, the central heater is adopted, so that the temperature gradient near the solid-liquid interface can be directly regulated, the uniformity of the temperature gradient of the solid-liquid interface is greatly improved, good V/G is obtained, and the perfect crystal yield of a semiconductor is greatly improved.
Description
Technical Field
The invention relates to the technical field of semiconductor monocrystalline silicon materials, in particular to a Czochralski monocrystalline silicon production device and a production method suitable for continuous feeding.
Background
Monocrystalline silicon is a basic material of the modern semiconductor industry and plays an important role in national economy. The silicon single crystal growth takes quartz sand as a raw material, the crust contains abundant silicon elements, the natural abundance of silicon is inferior to that of oxygen, the purity of silicon is improved to 8 '9' after decimal point by coke carbon reduction and other chemical purification methods, then a czochralski method or a zone-melting method is used for drawing a czochralski silicon rod to produce semiconductor grade silicon single crystal, and then the semiconductor silicon single crystal is obtained through the procedures of slicing, flooding, polishing, cleaning and the like.
Currently, the preparation of monocrystalline silicon mainly adopts the Czochralski method. The Czochralski method is to put a polysilicon material into a quartz crucible, heat the polysilicon material to a temperature of more than 1412 ℃ by a high-temperature heating mode, and then complete the growth of a silicon single crystal through a series of procedures of seeding, necking, shouldering, constant diameter, ending and the like. The silicon single crystal grown by the Czochralski method has the advantages of uniform impurity distribution, high mechanical strength and high internal gettering capability, so that the silicon single crystal can be widely applied to electronic devices and integrated circuits.
The main device for producing the Czochralski silicon is a single crystal growth furnace, which mainly comprises six parts, namely a furnace body, a crystal and crucible lifting and rotating device, an atmosphere and furnace pressure control system, an electric system, a crystal growth automatic control system, a thermal field and the like, and mainly comprises a main furnace chamber, an auxiliary chamber, a quartz crucible, a graphite crucible, a heater, a heat insulation material and the like, wherein the thermal field parts have critical influence on the control temperature distribution in the furnace, so that the quality of the single crystal silicon is influenced the most.
The main production flow of the Czochralski silicon is as follows: (1) charging and melting: and filling the electronic grade polycrystalline silicon material into a quartz crucible, putting the quartz crucible filled with the silicon material into a heatable graphite crucible, and heating the silicon material to be more than 1412 ℃ by a heater under inert atmosphere to completely melt the polycrystalline silicon. (2) temperature stabilization: gradually lowering the position of a seed crystal with a specific crystal orientation, preheating the seed crystal, slowly immersing the head of the seed crystal into the liquid level of the melt for welding, controlling the power of a heater to ensure proper free liquid level temperature, and forming a stable solid-liquid interface (3) for seeding: the seed crystal is slowly lifted, the seed crystal and the melt are adhered, and the carried melt forms crystals along with the temperature reduction. (4) necking: the seed crystal is pulled up at a faster rate and the grown crystal diameter is reduced to form a section of crystal having a diameter of about 3mm to exclude dislocations. (5) shoulder placing: after necking, the pulling speed is reduced, so that the diameter of the crystal is rapidly increased to reach the required diameter. (6) shoulder turning: before the crystal reaches the preset diameter, the pulling rate is increased to reduce the rate of increase of the crystal diameter until the crystal diameter does not continue to increase. (7) isodiametric: after the crystal reaches the preset diameter, the stable diameter growth of the crystal is ensured by the cooperation of a heater, a pulling speed and the like. (8) ending: and when the crystal growth is finished, the crystal growth rate is accelerated, the diameter is gradually reduced, and the crystal is gradually tapered to leave the liquid level. (9) furnace shutdown: and closing the heater, and performing operations such as furnace shutdown detection.
In order to reduce natural convection in a melt and reduce oxygen content, a magnetic control crystal pulling technology is generally adopted in modern semiconductor crystal pulling, namely a magnetic field with a certain intensity is applied to the outer side of a single crystal furnace, and the movement of the melt is restrained by Lorentz force by utilizing the conductivity of the melt so as to achieve the aim of reducing the turbulence intensity in the melt. The main magnetic field forms currently include the CUSP type and transverse magnetic fields.
In addition to impurities, defects in single crystal silicon can greatly affect the electrical performance of semiconductor devices, and therefore defects are also important indicators for measuring the quality of single crystal silicon. Wo Longke et al establish a set of mature intra-crystal defect formation mechanisms that consider defects in the crystal to be mainly affected by the pull rate and the temperature gradient ratio (V/G) at the solid-liquid interface, and when V/G is too large, vacancy-related defects will occur in the crystal, and when V/G is too small, interstitial-related defects will occur in the crystal. During the pulling process, the pull rate of the solid-liquid interface can be approximately considered to be uniform, and therefore, the quality of the crystal is mainly dependent on the temperature gradient at the solid-liquid interface, which is mainly affected by the thermal environment within the crystal, i.e., the furnace, and therefore, the thermal environment is critical to defects.
However, the control of the thermal field in the current single crystal furnace on the temperature is not ideal, and the temperature gradient at the solid-liquid interface is difficult to accurately adjust, so that the uncontrollable defect area is caused, and the yield of the perfect crystal of the current semiconductor grade silicon single crystal is lower. Therefore, there is a need to develop an effective device and method for controlling impurities and defects in monocrystalline silicon, and to greatly improve the yield of perfect crystals of monocrystalline silicon.
Disclosure of Invention
In view of the above, the invention aims to provide a Czochralski silicon production device suitable for continuous feeding, which is used for producing and preparing high-purity and low-defect large-size silicon wafers, greatly improves the yield and the productivity of the silicon wafers, and meets the requirements of the semiconductor industry.
Another object of the present invention is to provide a method for producing a semiconductor silicon single crystal using the above-mentioned Czochralski silicon production apparatus suitable for continuous charging.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
the Czochralski silicon production device suitable for continuous feeding comprises a quartz crucible, a supporting crucible, a heater, a heat shield, a heat insulation material, a main chamber and an auxiliary chamber, wherein the quartz crucible is a double crucible, and the center of the bottom of the crucible is of a concave structure; the heater includes a side heater and a center heater located within a concave configuration at the center of the bottom of the crucible.
In a specific embodiment, the double crucible is composed of an inner crucible and an outer crucible, wherein the inner crucible and the outer crucible are communicated at the bottom, the diameter of the outer crucible is 1.1-1.2 times that of the inner crucible, and the height of the communicating part from the bottom of the crucible is 1/4-1/2 of the total height of the inner crucible.
In a preferred embodiment, the inner quartz crucible has a diameter of 28-40 inches and a cylindrical concave configuration at the center of the bottom of the crucible; more preferably, the diameter of the cylinder is 200-500mm, and the height of the cylinder is 1/3-2/3 of the height of the quartz crucible; further preferably, the wall thickness of the concave structure is the same as the wall thickness of the quartz crucible.
In a specific embodiment, the supporting crucible is made of tungsten metal, and a concave structure is arranged at the center of the bottom of the supporting crucible and used for supporting the quartz crucible, and the supporting crucible is preferably formed by combining and splicing 2-3 petals.
In a specific embodiment, the side heater and/or the center heater is a tungsten metal.
In a preferred embodiment, the central heater is a single cylinder or a combination of cylinders; more preferably, the diameter of any cylinder is 50-450mm, the sum of the diameters of the cylinders is 300-450mm, and the height of the cylinder is 1/3-2/3 of the height of the quartz crucible.
In a specific embodiment, the thermal insulation material is attached with SiO 2 A coated carbon composite; preferably, siO 2 The coating is deposited by adopting a vapor phase growth method, the thickness of the coating is 1-5mm, and the surface emissivity is less than 0.1.
In another aspect, the aforementioned Czochralski silicon production apparatus adapted for continuous charging is used in a method for producing a Czochralski silicon single crystal, comprising the steps of:
1) Finishing the forefront preparation work of charging, calcining and leak detection, preferably, the bottom of the heat shield is 20-60mm away from the free liquid level of the silicon melt;
2) Maintaining the vacuum degree in the furnace, introducing high-purity argon, filling polycrystalline silicon materials, and opening a side heater and a central heater to melt the silicon materials;
3) Starting seed crystal and crucible rotation, preferably 10-20rpm for crystal rotation and 0.1-10rpm for crucible rotation, and then sequentially performing the procedures of seeding, shouldering, isodiametric, ending and rod taking.
In a specific embodiment, a continuous feed apparatus is used to continuously feed semiconductor grade polycrystalline silicon feedstock to a crucible during a crystal pulling process; preferably, a continuous feeder and a continuous feed port are used and feed is performed at a position away from the central liquid level on the side of the outer crucible wall surface.
In a specific embodiment, a superconducting magnetic field is used, the magnetic field strength is continuously adjustable, and the maximum magnetic field strength is 3000-4000GS.
In a specific embodiment, during the seeding to finishing stage, the continuous feeder is opened and the feed rate is adjusted according to the change in weight of the ingot so that the total amount of melt remains unchanged and the free level of the melt does not change by more than 0.1mm.
In a specific embodiment, the power of the central heater at the axis of the crucible and the power of the side heater at the side wall of the crucible are continuously adjustable, the power adjustment range is 0-400kW, and the control precision is 0.1-1kW; preferably, the central heater remains on during the entire crystal pulling process and is used in conjunction with the main heater.
In a specific embodiment, when a plurality of cylindrical heater groups are used to form a central heater, the heater groups are arranged in such a way that one small cylindrical heater is placed at the center, 4-8 small cylindrical heaters are uniformly distributed around in a circular shape, and the ratio of the power of the surrounding cylindrical heaters to the power of the central small cylindrical heater is 2-8:1.
compared with the prior art, the invention has the following beneficial effects:
1) The Czochralski silicon production device suitable for continuous feeding adopts the central heater to directly adjust the temperature gradient near the solid-liquid interface, so that the uniformity of the temperature gradient of the solid-liquid interface can be greatly improved, good V/G is obtained, and the perfect crystal yield of a semiconductor is greatly improved.
2) The Czochralski silicon production device suitable for continuous feeding adopts continuous feeding devices such as the inner crucible, the outer crucible, the continuous feeder and the like, can continuously produce a large amount of high-quality semiconductor monocrystalline silicon, obtains larger productivity, can maintain the height of a solid-liquid interface under the condition of unchanged crucible position, does not change parameters such as radiation heat exchange angle coefficient and the like in the furnace body, and maintains the stability of the internal thermal environment of the furnace.
3) The heater is prepared from the metal tungsten, so that the volatilization of carbon is reduced, and the surface of the heat-insulating material is completely covered with SiO 2 The coating reduces the emissivity and improves the heat preservation effect, simultaneously reduces the volatilization of carbon in the furnace, and can reduce the carbon and oxygen content in the crystal bar by matching with a superconducting magnetic fieldTo ultra-low levels.
Drawings
Fig. 1 is a schematic structural view of a Czochralski silicon production apparatus suitable for continuous charging in accordance with the present invention.
FIG. 2 is a graph showing the comparison of the simulation results of the temperature gradient distribution at the solid-liquid interface of the examples and the comparative examples.
Wherein, 1, auxiliary chamber; 2. a tungsten wire lifting rope; 3. seed crystal; 4. a crystal bar; 5. a heat shield; 6. an inner crucible; 7. an outer crucible; 8. a feed inlet; 9. a furnace cover; 10. an upper heat preservation layer; 11. a superconducting magnetic field; 12. supporting the crucible; 13. a central heater; 14. a middle heat preservation layer; 15. a side heater; 16. a bottom insulation layer; 17. silicon melt
Detailed Description
For a better understanding of the technical solution of the invention, the method provided by the invention is further described below, but the invention is not limited to the examples listed but also includes any other known modifications within the scope of the claims of the invention.
The invention relates to a Czochralski silicon production device suitable for continuous feeding, which comprises a quartz crucible, a supporting crucible, a side heater, a central heater, a heat shield, a heat insulation material, a main chamber, an auxiliary chamber and the like, and has the main functions of preparing a semiconductor grade ultrapure monocrystalline silicon rod with the diameter of more than 200 mm. The production device provided by the invention is matched with a continuous feeding device, and the semiconductor grade polycrystalline silicon raw material is continuously fed into the crucible in the crystal pulling process, so that continuous crystal pulling can be realized, and the production efficiency is improved.
The invention relates to a Czochralski silicon production device suitable for continuous feeding, namely a crystal growth furnace or a single crystal furnace which is commonly known in the field, and the key of the invention is the arrangement of a central heater and the improvement of a matched crucible, and other parts and connection modes thereof are not particularly described, so that reference is made to the prior art. Meanwhile, the double crucible and the continuous crystal pulling technology can refer to the prior art, the structure of the double crucible is improved only on the basis of the prior art, and the double crucible is matched with a central heater for use, so that the temperature gradient near a solid-liquid interface can be directly regulated, the uniformity of the temperature gradient of the solid-liquid interface can be greatly improved, good V/G is obtained, and the perfect crystal yield of a semiconductor is greatly improved.
As shown in figure 1, a Czochralski silicon production device suitable for continuous feeding comprises a furnace cover 9 and an auxiliary chamber 1, wherein the heat insulation material in the main furnace chamber comprises a bottom heat insulation layer 16, a middle heat insulation layer 14 and an upper heat insulation layer 10, is used for heat insulation and heat preservation of a furnace body, and is for example formed by wrapping SiO on the surface of a hard carbon felt completely 2 Coating, reducing the introduction of carbon impurities, siO 2 The coating is for example prepared using a vapor phase growth method, preferably the thickness of the coating is 1-5mm, including for example but not limited to 1mm, 2mm, 3mm, 4mm, 5mm, etc., with a surface emissivity of less than 0.1. The inner side of the middle heat preservation layer is provided with a side heater 15, the inside of the side heater 15 is provided with a quartz crucible and a supporting crucible, the quartz crucible is composed of an outer crucible 7 and an inner crucible 6, the inner crucible and the outer crucible are communicated at the bottom, the diameter of the outer crucible 7 can be 28-40 inches, the middle heat preservation layer is provided with a special-shaped structure, specifically, a cylindrical concave structure is arranged at the center of the bottom of the crucible, namely, a cylindrical structure is recessed inwards from the bottom, the diameter of the cylindrical structure is 300-500mm, such as 300mm, 350mm, 400mm, 450mm, 500mm and the like, the height of the cylindrical concave structure is 1/3-2/3 of the height of the quartz crucible, namely, 1/3-2/3 of the height of the quartz crucible is recessed inwards, and the wall thickness of the concave structure is consistent with the wall thickness of the quartz crucible. The outer crucible 7 is used for continuously receiving the polysilicon charge, the diameter of the outer crucible is about 1.1-1.2 times of the diameter of the inner crucible, the height of the communicating hole from the bottom of the inner crucible is 1/4-1/2, such as 1/4, 1/3, 1/2, and the like, and the maximum height is not more than 1/2, so as to ensure the stability of the liquid level. The height of the inner crucible is the distance from the top point of the end part of the open end of the inner crucible to the joint of the inner crucible and the bottom of the crucible. The number, size and shape of the communication holes are not particularly limited, and reference may be made to the prior art such as at least one circular communication hole, or square, triangular, etc., but not limited thereto.
The quartz crucible is supported by the support crucible 12, and is made of tungsten metal, and the tungsten crucible has high heat conductivity, high melting point and is not easy to introduce carbon impurities. In general, the support crucible may be an integrated crucible or a split type, for example, a combined crucible formed by splicing two, three or four or more pieces, and is used for supporting the quartz crucible inside. Correspondingly, the bottom of the supporting crucible is provided with a concave structure matched with the adapting crucible so as to support the quartz crucible and arrange a central heater. The support crucible recess is provided with a central heater 13 of a metallic tungsten material for preventing introduction of carbon impurities, and the central heater is a single cylinder or a combination of multiple cylinders. For example, a large single cylinder central heater, or a plurality of small cylinders as the central heater, and when a combination of multiple cylinders is used, the cylinders are uniformly distributed, preferably one cylinder is located at the center and the other cylinders are uniformly distributed in the circumferential direction. The diameter of the individual heaters is in the range of 50-450mm according to the number of cylindrical heaters, and the total diameter of the heaters is 300-450mm, i.e. 300-450mm in the case of a single cylinder; in the case of multiple cylinders, the sum of the diameters of all small cylinders is 300-450mm. This diameter corresponds to the diameter of the single crystal silicon rod, and the height of the cylinder is 1/3-2/3 of the height of the quartz crucible, which should be slightly smaller than the height of the concave structure, for example, it is generally ensured that the heater is about 10mm from the crucible wall. Likewise, the diameter of the central heater is slightly smaller than the inner diameter of the cavity of the concave structure, so that the central heater can be accommodated in the cavity, and the central heater can be prevented from directly touching the surface of the crucible; the top surface and the side surface of the central heater are heating surfaces, and a sufficient amount of heat source is provided for the quartz crucible. The invention uses the heat shield 5, the bottom of the heat shield is 20-60mm away from the free liquid level of the silicon melt, a reasonable argon flow passage is provided, and SiO gas of the silicon melt is taken away in time. The superconducting magnetic field is used outside the furnace body, the magnetic field intensity is continuously adjustable, and the maximum magnetic field intensity can reach 3000-4000GS.
On the other hand, the production device is used for the production method of the ultrapure czochralski silicon device, after the preliminary preparation work such as calcination leak detection is finished, the vacuum degree in the furnace is kept, high-purity argon is introduced, the polycrystalline silicon material is filled, the side heater and the central heater are opened, the silicon material is melted, the seed crystal and the crucible are started to rotate, wherein the crystal is turned to 10-20rpm, the crucible is turned to 0.1-10rpm, and then the stages such as seeding, shouldering, isodiametric, ending and rod taking are sequentially carried out. In the stage from seeding to ending, starting a continuous feeder according to the weight change of the crystal bar and adjusting the feeding rate to ensure that the total amount of the melt is kept unchanged, the free liquid level of the melt is not changed by more than 0.1mm, the power of a central heater at the axis of the crucible and the power of a side heater at the side wall of the crucible are continuously adjustable, the power adjusting range is 0-100kW, and the control precision is 0.1-1kW.
In the whole crystal pulling process, the central heater is kept on and is matched with the side heaters to jointly control the temperature distribution in the melt and the pulling rate of crystals, when a plurality of cylindrical heater groups are used for forming the central heater, the arrangement mode of the heater groups is that one small cylindrical heater is placed at the center, 4-8 small cylindrical heaters are uniformly distributed around in a circular shape, and the ratio of the power of the surrounding cylindrical heaters to the power of the central small cylindrical heater is preferably 2-8:1, for example 2: 1. 3: 1. 4: 1. 5: 1. 6: 1. 7: 1. 8:1, etc. In the crystal pulling process, the temperature gradient near the solid-liquid interface is regulated and controlled, and the crystal rotation/crucible rotation of the crystal growth process is matched, wherein the crystal rotation range is 10-20rpm, the crucible rotation range is 0.1-10rpm, and an adjustable magnetic field of 0-4000GS is added, so that a proper growth rate is obtained, an accurate and proper V/G ratio is further obtained, and the aim of high perfect crystal yield is fulfilled.
Specifically, referring to fig. 1, a method of using a continuously charged center heating ultrapure straight pulling apparatus, a bottom heat insulating layer 16 and a middle heat insulating layer 14 are installed after furnace cleaning, side heaters 15 and a center heater 13 are installed, and a support crucible 12 is installed above a crucible support. The quartz crucible is installed, the quartz crucible is kept tightly attached to the supporting crucible 12, and the central heater 13 is ensured to smoothly enter the inner cavity of the concave structure of the outer crucible 7 of the quartz crucible, and then the electronic grade polycrystalline silicon material is filled. An insulating layer 10 and a heat shield 5 are arranged. And (3) performing the steps of evacuating and detecting leakage, and after the steps are finished, turning on the central heater 13 and the side heaters 15 to completely melt the polysilicon material to form a silicon melt 17, and turning on the superconducting magnetic field 11. The seed crystal 3 is contacted with the free liquid surface of the silicon melt 17 by using a tungsten wire lifting rope 2, so that the seed crystal is welded. Under certain technological parameters such as crystal/crucible rotation, pulling speed and the like, the crystal rod 4 is pulled after a plurality of technological processes such as crystal seeding, shouldering, isodiametric, ending and the like. During the drawing, the continuous feeder continuously feeds semiconductor grade polysilicon material between the inner crucible 6 and the outer crucible 7 through the feed port 8 according to the change of the residual quantity of the melt in the crucible, so that the liquid level of the melt is maintained at the same height, and the stability and the continuity of the drawing are ensured. In the whole crystal pulling process, the heating power of the side heater 15 and the heating power of the central heater 13 are continuously adjustable, the rated power of the side heater 15 and the rated power of the central heater 13 are 0-200kW, the control precision is 0.1-1kW, the temperature gradient near a solid-liquid interface is regulated and controlled by continuously adjusting the heating power of the central heater 13, the crystal/crucible rotation of a crystal growth process is matched, the crystal rotation range is 10-20rpm, the crucible rotation range is 0.1-10rpm, an adjustable magnetic field of 0-4000GS is added, the proper growth rate is obtained, the precise and proper V/G ratio is further obtained, and the aim of high yield is achieved.
The invention is further illustrated by the following examples, which are given by way of illustration only and are not to be construed as limiting the invention in any way.
Examples
The inner diameter of the single crystal furnace of the embodiment is 1600mm, and the single crystal furnace is used for growing 300mm single crystal silicon rods. The diameter of the inner quartz crucible used was 32 inches, and the diameter of the outer crucible was 1.1 times the diameter of the inner crucible. A single tungsten columnar heater is adopted, the diameter of the heater is 300mm, and the height of the heater is 1/3 of the height of the quartz crucible. The rated heating power of the side heater is 200kW, and the rated heating power of the central heater is 200kW. The inner diameter of the superconducting magnetic field is 1800mm, and the magnetic induction intensity is 0-4000GS and is continuously adjustable. And a heat shield is adopted, and the bottom of the heat shield is 60mm away from the free liquid level of the silicon melt.
And (3) after the furnace is cleaned, a bottom heat preservation layer and a middle heat preservation layer are arranged, a side heater and a center heater are arranged, and the support crucible is arranged above the crucible support. And installing the quartz crucible, keeping the quartz crucible tightly attached to the supporting crucible, and ensuring that the central heater smoothly enters the reserved empty chamber of the quartz crucible. Then 400kg of electronic grade polysilicon charge was charged. And installing a top heat preservation layer and a heat shield. And (3) operating the steps of evacuating and detecting leakage, and after the steps are finished, opening a central heater and a side heater, setting the crucible to be 2rpm, and completely melting the polycrystalline silicon material to form a silicon melt. Turning on superconducting magnetic field to induce strong magnetic inductionThe degree is set to 4000GS. Setting the crystal rotation to 10rpm, the crucible rotation to 9rpm, and controlling the temperature of the free liquid level through a central heater, and using a tungsten wire lifting rope to contact the seed crystal with the free liquid level of the silicon melt so as to weld the seed crystal. And carrying out seeding and shouldering operation under the condition that the crystal is turned to 10rpm and the crucible is turned to 9 rpm. As the ingot grows, the magnetic induction is reduced from 4000GS to 1000GS at a rate of 55 GS/hour from the beginning to the end of the isodiametric. During drawing, the continuous feeder continuously adds semiconductor grade polysilicon material between the inner crucible and the outer crucible through the feeding port according to the change of the residual amount of the melt in the crucible, so that the liquid level of the melt is maintained at the same height, and the stability and the continuity of the drawing are ensured. In the whole crystal pulling process, the heating power of the central heater is continuously changed, the temperature gradient near the solid-liquid interface is regulated and controlled to obtain the growth rate of 0.55+/-0.05 mm/min, and the V/G is maintained at the critical value of 0.12-0.2mm 2 In the range of/K/min, high perfect crystal yield of the semiconductor is realized. And continuously drawing a plurality of single crystal silicon rods with proper lengths within the service life of the crucible, stopping feeding, maintaining the free liquid level height unchanged through crucible lifting, and drawing the last crystal rod. Gradually reducing the magnetic induction intensity to 1000GS at the speed of 55 GS/hour from the beginning to the end of the equal diameter, then carrying out the ending process, and finally executing the processes of furnace shutdown and the like.
Comparative example
In comparison to the examples, the single crystal furnace and magnetic field and associated thermal field components used in the comparative example were kept unchanged, the central heater was simply eliminated, and crystal growth was performed using a conventional round bottom quartz crucible and a round bottom tungsten support crucible.
Similarly, the bottom and middle heat-insulating layers are installed after furnace cleaning, the bottom and side heaters are installed, and the support crucible is installed above the crucible support. And installing the quartz crucible, keeping the quartz crucible tightly attached to the supporting crucible, and ensuring that the central heater smoothly enters the reserved empty chamber of the quartz crucible. Then 400kg of electronic grade polysilicon charge was charged. And installing a top heat preservation layer and a heat shield. And (3) operating the steps of evacuating and detecting leakage, and after the steps are finished, opening a bottom heater and a side heater, setting the crucible to be 2rpm, and completely melting the polycrystalline silicon material to form a silicon melt. The superconducting magnetic field was turned on and the magnetic induction was set at 4000GS. Setting the crystal rotation to 10rpm, the crucible rotation to 9rpm, and controlling the temperature of the free liquid level through a central heater, and using a tungsten wire lifting rope to contact the seed crystal with the free liquid level of the silicon melt so as to weld the seed crystal. And carrying out seeding and shouldering operation under the condition that the crystal is turned to 10rpm and the crucible is turned to 9 rpm. As the ingot grows, the magnetic induction is reduced from 4000GS to 1000GS at a rate of 55 GS/hour from the beginning to the end of the isodiametric. During drawing, the continuous feeder continuously adds semiconductor grade polysilicon material between the inner crucible and the outer crucible through the feeding port according to the change of the residual amount of the melt in the crucible, so that the liquid level of the melt is maintained at the same height, and the stability and the continuity of the drawing are ensured. And continuously drawing a plurality of single crystal silicon rods with proper lengths within the service life of the crucible, stopping feeding, maintaining the free liquid level height unchanged through crucible lifting, and drawing the last crystal rod. The magnetic induction intensity of 55 GS/hour is gradually reduced to 1000GS from the beginning to the end of the equal diameter, and then the ending process is carried out. And finally, executing the processes of furnace shutdown and the like.
FIG. 2 shows a comparison of normalized solid-liquid interface temperature gradients for a center-on-center heater and a non-center-on-center heater, as calculated by simulation, showing a large variation in the temperature gradient at the solid-liquid interface with a wide distribution range for the non-center-on-center heater; after the central heater is installed, the temperature gradient distribution at the solid-liquid interface is obviously narrowed, the span of the temperature gradient distribution is only 8% of that of the temperature gradient distribution without the central heater, and the temperature gradient distribution has good temperature gradient flatness. According to the V/G theory of Wo Longke f, the defect can be reduced to the minimum value when the V/G reaches the critical value, and under the condition that the pulling speed on the solid-liquid interface is basically kept unchanged, the temperature gradient directly determines the distribution range of the V/G of the solid-liquid interface, therefore, the central heater is used for helping to greatly reduce the distribution range of the V/G, and the V/G value on the whole silicon wafer is enabled to fall near the critical value, so that perfect single crystals are pulled out, and the high product yield is obtained.
While the present invention has been described in detail by reference to the preferred embodiments described above, and while the validity of the present invention has been demonstrated by comparison, it should be recognized that the embodiments do not limit the present invention. It will be appreciated by persons skilled in the art that modifications and adaptations of the invention are possible and can be made within the scope of the invention as defined in the claims.
Claims (10)
1. The Czochralski silicon production device suitable for continuous feeding comprises a quartz crucible, a supporting crucible, a heater, a heat shield, a heat insulation material, a main chamber and an auxiliary chamber, and is characterized in that the quartz crucible is a double crucible, and the center of the bottom of the crucible is of a concave structure; the heater includes a side heater and a center heater located within a concave configuration at the center of the bottom of the crucible.
2. The apparatus for producing Czochralski silicon suitable for continuous feeding as claimed in claim 1, wherein the double crucible is composed of an inner crucible and an outer crucible, the inner crucible and the outer crucible are communicated at the bottom, the diameter of the outer crucible is 1.1-1.2 times of the diameter of the inner crucible, and the height of the communicating part from the bottom of the crucible is 1/4-1/2 of the total height of the inner crucible; preferably, the inner quartz crucible has a diameter of 28-40 inches, with a cylindrical concave configuration at the center of the bottom of the crucible; more preferably, the diameter of the cylinder is 200-500mm, and the height of the cylinder is 1/3-2/3 of the height of the quartz crucible; further preferably, the wall thickness of the concave structure is the same as the wall thickness of the quartz crucible.
3. The apparatus for producing Czochralski silicon suitable for continuous feeding as claimed in claim 1, wherein the supporting crucible is made of tungsten metal, and the center of the bottom of the supporting crucible is provided with a concave structure for supporting the quartz crucible, preferably formed by 2-3 pieces of the supporting crucible in a combined and spliced manner.
4. The apparatus for producing czochralski silicon suitable for continuous charging of claim 1, wherein the side heater and/or the central heater is of tungsten metal; preferably, the central heater is a single cylinder or a combination of cylinders; more preferably, the diameter of any cylinder is 50-450mm, the sum of the diameters of the cylinders is 300-450mm, and the height of the cylinder is 1/3-2/3 of the height of the quartz crucible.
5. The apparatus for producing Czochralski silicon suitable for continuous feed as claimed in claim 1, wherein the insulating material is SiO-attached 2 A coated carbon composite; preferably, siO 2 The coating is deposited by adopting a vapor phase growth method, the thickness of the coating is 1-5mm, and the surface emissivity is less than 0.1.
6. A method for producing Yu Zhila single crystal silicon for a Czochralski silicon production apparatus adapted for continuous feeding as claimed in any one of claims 1 to 5, comprising the steps of:
1) Finishing the forefront preparation work of charging, calcining and leak detection, preferably, the bottom of the heat shield is 20-60mm away from the free liquid level of the silicon melt;
2) Maintaining the vacuum degree in the furnace, introducing high-purity argon, filling polycrystalline silicon materials, and opening a side heater and a central heater to melt the silicon materials;
3) Starting seed crystal and crucible rotation, preferably 10-20rpm for crystal rotation and 0.1-10rpm for crucible rotation, and then sequentially performing the procedures of seeding, shouldering, isodiametric, ending and rod taking.
7. The method of claim 6, wherein the continuous feed device is used to continuously feed semiconductor grade polycrystalline silicon feedstock to the crucible during the crystal pulling process; preferably, a continuous feeder and a continuous feed port are used, and the material is fed at a position far from the central liquid level on the wall surface side of the outer crucible;
preferably, a superconducting magnetic field is used, the magnetic field strength is continuously adjustable, and the maximum magnetic field strength is 3000-4000GS.
8. The method according to claim 6, wherein the continuous feeder is opened and the feeding rate is adjusted according to the change in the weight of the ingot so that the total amount of the melt is kept constant and the free liquid level of the melt does not change by more than 0.1mm in the seeding to finishing stage.
9. The method of claim 6, wherein the central heater at the axis of the crucible and the side heaters at the side walls of the crucible are continuously adjustable in power, the power adjustment ranges from 0kW to 400kW, and the control accuracy is from 0.1 kW to 1kW; preferably, the central heater remains on during the entire crystal pulling process and is used in conjunction with the main heater.
10. The production method as claimed in claim 6 or 9, wherein when a plurality of cylindrical heater groups are used to construct the central heater, one small cylindrical heater is placed at the center of the heater group in an arrangement such that 4 to 8 small cylindrical heaters are uniformly distributed around in a circle, and a ratio of power of the surrounding cylindrical heater to power of the central small cylindrical heater is 2 to 8:1.
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