CN105420813A - Doping-element-free high-purity semi-insulating silicon carbide crystal growing device - Google Patents
Doping-element-free high-purity semi-insulating silicon carbide crystal growing device Download PDFInfo
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- CN105420813A CN105420813A CN201510972097.7A CN201510972097A CN105420813A CN 105420813 A CN105420813 A CN 105420813A CN 201510972097 A CN201510972097 A CN 201510972097A CN 105420813 A CN105420813 A CN 105420813A
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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
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/36—Carbides
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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
- C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
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Abstract
The invention discloses a doping-element-free high-purity semi-insulating silicon carbide crystal growing device. The device solves the problem of production of low-purity high-purity silicon carbide crystals. The device comprises a high-purity graphite crucible (2), wherein a graphite felt insulating layer (7) is arranged on the outer side surface of the high-purity graphite crucible (2); a lower temperature measuring hole (8) and an upper temperature measuring hole (9) are formed in the graphite felt insulating layer (7) respectively; a graphite support (1) is arranged on the top of the inner cavity of the high-purity graphite crucible (2); a seed crystal (4) is arranged on the graphite support (1); a silicon carbide crystal (5) after growth is arranged on the seed crystal (4); SiC high-purity powder (3) is arranged at the lower part inside the cavity of the high-purity graphite crucible (2); and a small hole (6) is formed between the graphite support (1) and the inner side wall of the inner cavity of the high-purity graphite crucible (2). The invention aims to obtain the high-purity silicon carbide crystals by reducing the concentration of impurity elements in a background.
Description
Technical field
The present invention relates to a kind of carborundum crystals preparation facilities, in particular to a kind of method preparing high-purity semi-insulating 4H-SiC crystal, the method increases intrinsic point defects concentration method after mainly first reducing crystal growth front Background impurity concentration carrys out the difference of compensate shallow alms giver and shallow acceptor energy level, thus obtains the technique of the growth high-purity semi-insulating silicon carbide crystalloid of semi-insulating effect.
Background technology
Silicon carbide is continue first-generation semiconductor silicon, germanium, the third generation semiconductor material after s-generation Semiconductor GaAs, indium phosphide.Silicon carbide has high heat conductance, high breakdown field strength, high saturated electrons rate of migration and stable process based prediction model, be preparation insulation, high frequency, superpower and and anti-electromagnetic-radiation aspect there is broad mass market.Semi insulating silicon carbide silicon substrate material is the preferred material preparing high performance microwave power device, usually mixes vanadium and can obtain semi insulating silicon carbide silicon substrate material, but when high temperature, the precipitation of vanadium can cause a kind of back-gate effect and cause the reduction of semi-insulating effect.In order to prepare the microwave power device of high stable performance, need to prepare high-purity semi-insulating silicon carbide to do the communication device that substrate material prepares airborne radar, shipborne radar.
The common method of great diameter SiC crystal preparation is physical vapor transport (PhysicalVaporTransport).Sic powder is placed on the crucible bottom of airtight graphite composition, crucible top fixes a seed crystal, and the diameter of seed crystal will determine the diameter of crystal.Powder will reach sublimation temperature point under the effect of ruhmkorff coil, Si, C, Si2C and SiC2 molecule that distillation produces is transferred to seed crystal face from raw material surface under the effect of axial-temperature gradient, because seed crystal back is made up of louvre, so relatively cold at seed portion, under the effect of axial-temperature gradient, reach the object of growing crystal like this in the slow crystallization of seed crystal face.Traditional growth method owing to introducing the impurity elements such as nitrogen, boron, aluminium, vanadium and iron unavoidably in graphite material and powder, due to the state that crucible is airtight, the impurity of crucible inside is difficult to avoid entering crystals, causes being difficult to the very low high purity silicon carbide crystals of growth foreign matter content.
Summary of the invention
The invention provides a kind of high-purity semi-insulating silicon carbide crystalloid growing apparatus of non-impurity-doped element, the difficult problem that the high purity silicon carbide crystals solving low impurity is produced.
The present invention solves above technical problem by the following technical programs:
A kind of high-purity semi-insulating silicon carbide crystalloid growing apparatus of non-impurity-doped element, comprise high purity graphite crucible, the outer side of high purity graphite crucible is provided with graphite felt thermal insulation layer, graphite felt thermal insulation layer is respectively arranged with lower thermometer hole and upper thermometer hole, the inner cavity top of high purity graphite crucible is provided with graphite support, graphite support is provided with seed crystal, seed crystal is provided with the carborundum crystals after growth, in the chamber of high purity graphite crucible, bottom is provided with SiC highly pure powder, in graphite support and high purity graphite crucible, be provided with aperture between chamber inner sidewall.
Distance between the end face of SiC highly pure powder and the bottom surface of seed crystal is 50-60 millimeter, and the diameter of lower thermometer hole and the diameter of upper thermometer hole are 10-20 millimeter.
Reduce carborundum crystals impurity and obtain the method for high-purity semi-insulating silicon carbide crystalloid, comprising the following steps:
The first step, seed crystal is bundled in graphite support, seed crystal is placed on crucible top, SiC highly pure powder is placed on the bottom of growth chamber, powder apart from seed crystal apart from about 50-60 millimeter;
Carry out isothermal holding by graphite felt around crucible when second step, growth, respectively there is the louvre of a 10-20 millimeter crucible top and bottom to obtain suitable axial-temperature gradient, are measured the temperature in growth chamber by this hole high-temperature infrared instrument simultaneously.
For existing growth technique technology, the object of the invention obtains high purity silicon carbide crystals by the impurity element concentration reduced in background, carry out high temperature to the wafer after cutting cool fast thus increase point defect concentration, the point defect of increase is enough to the mode of the difference of compensate shallow alms giver and shallow acceptor to reach semi-insulated object.The method of major diameter high-purity semi-insulating 4H-SiC crystal is prepared in final acquisition.For realizing above object, the present invention is a kind of method preparing high-purity semi-insulating 4H-SiC, mainly realizes the growth technique method of semi-insulating effect deliberately not mixing deep energy level compensating elements.The method equally still uses conventional physical vapor transport grow silicon carbide crystals.When growing crystal, to the top edge portion of plumbago crucible, main purpose be allow impurity element nitrogen, boron, aluminium, vanadium and iron in plumbago crucible material itself and sic powder early growth period temperature reach spend about 1950-2050 greatly time, growth pressure controls at 600-800mbar, just in time reach the sublimation point of the impurity such as background impurities elemental nitrogen, boron, aluminium, vanadium, allow the nitrogen in background, boron, aluminium, vanadium first distil, thus the impurity concentration reduced in background obtain high purity silicon carbide crystals.Standard wafer is cut into the crystal grown, then the quick cooling process of high temperature is carried out to the wafer after cutting, main purpose increases the point defect concentration in crystal, increase in carborundum crystals and form primary point defect, this point defect is enough to the concentration difference of compensate shallow alms giver and shallow acceptor, thus reach semi-insulating effect, the wherein difference of concentration of the shallow donor that formed higher than the involuntary doping in carborundum crystals of the primary point defect concentration of semi-insulating silicon carbide crystalloid and shallow acceptor.The size control of the edge aperture of the graphite top cover that this invention is mainly concerned with is at six apertures of 0.5-2 millimeter, aperture main purpose allows the impurity element in growth chamber discharge in the early stage of growth, particularly produce shallow donor impurity elemental nitrogen element can be unlikely to when beginning growing crystal in early growth period spilling and carry out in crystal, just be difficult to obtain semi-insulating effect once carry out crystal, the crystal obtained according to this kind of method is high-purity crystal.Wafer controls about 1800-1900 degree in the temperature that high temperature cools fast, and the primary point defect of generation is carbon room, silicon room or silicon-carbon divacancy/antiposition.The carborundum crystals that the present invention relates to comprises 4H-SiC and 6H-SiC crystal.Temperature was reduced to less than 1500 degree from 1800-1900 degree fast by wafer time used in quick process of cooling in 20-100 minute.
Accompanying drawing explanation
Fig. 1 is the growth chamber structural representation of physical vapor transport of the present invention growth SiC crystal.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in detail:
A kind of high-purity semi-insulating silicon carbide crystalloid growing apparatus of non-impurity-doped element, comprise high purity graphite crucible 2, the outer side of high purity graphite crucible 2 is provided with graphite felt thermal insulation layer 7, graphite felt thermal insulation layer 7 is respectively arranged with lower thermometer hole 8 and upper thermometer hole 9, the inner cavity top of high purity graphite crucible 2 is provided with graphite support 1, graphite support 1 is provided with seed crystal 4, carborundum crystals 5 after seed crystal 4 is provided with growth, in the chamber of high purity graphite crucible 2, bottom is provided with SiC highly pure powder 3, aperture 6 is provided with between chamber inner sidewall in graphite support 1 and high purity graphite crucible 2.
Distance between the end face of SiC highly pure powder 3 and the bottom surface of seed crystal 4 is 50-60 millimeter, and the diameter of lower thermometer hole 8 and the diameter of upper thermometer hole 9 are 10-20 millimeter.
Reduce carborundum crystals impurity and obtain the method for high-purity semi-insulating silicon carbide crystalloid, comprising the following steps:
The first step, seed crystal is bundled in graphite support 1, seed crystal 3 is placed on crucible top, SiC highly pure powder 3 is placed on the bottom of growth chamber, powder apart from seed crystal apart from about 50-60 millimeter;
Carry out isothermal holding by graphite felt around crucible when second step, growth, respectively there is the louvre of a 10-20 millimeter crucible top and bottom to obtain suitable axial-temperature gradient, are measured the temperature in growth chamber by this hole high-temperature infrared instrument simultaneously.
The present invention is a kind of high-purity semi-insulating silicon carbide crystalloid growth method of non-impurity-doped element, and heated the high vacuum plumbago crucible in silica tube by the method for induction heating, graphite material all adopts high purity graphite.Carry out isothermal holding by graphite felt around crucible during growth, respectively there is the louvre of a 10-20 millimeter crucible top and bottom to obtain suitable axial-temperature gradient, measure growth cavity temperature by this hole high-temperature infrared instrument simultaneously.
Preparing in the method for high-purity semi-insulating silicon carbide crystalloid above, the v element that deliberately do not adulterate carrys out the energy level difference of compensate shallow alms giver and shallow acceptor, by using conventional physical vapor transport grow silicon carbide crystals, in process of growth, the top of plumbago crucible is opened 6 apertures symmetrically, the diameter scope control of wherein said aperture is at 0.5-2 millimeter.The main purpose of aperture is the nitrogen allowed in the background of growth front, boron, aluminium, vanadium and iron contamination element overflow from aperture, thus the impurity element in minimizing background enters crystal to reduce the impurity acquisition high purity silicon carbide crystals in crystal, when growth temperature controls when spending about 1950-2050 greatly, growth pressure controls at 600-800mbar, just in time reach background impurities elemental nitrogen, boron, aluminium, the spilling temperature spot of the impurity such as vanadium, allow nitrogen in background, boron, aluminium, vanadium carries out elder generation and overflows from aperture, thus the impurity concentration in reduction background obtains high purity silicon carbide crystals, continue again afterwards to increase the growth pressure in growth temperature and step-down growth chamber, when growth temperature reaches the sublimation temperature 2050-2250 of sic powder, growth chamber internal pressure controls when 5-100mabr, sic powder starts distillation, edge aperture progressively seals up by the sic powder of distillation, thus the quasi-balanced state ensureing to be quasi-balanced state in growth chamber and meet growing silicon carbice crystals requires to carry out crystal growth.
Next step is undertaken cutting into silicon carbide wafer by growing the carborundum crystals after terminating, the quick cooling process of high temperature is carried out to silicon carbide wafer, the major equipment used is box high-temperature annealing furnace, this stove can arrange different warm areas, can protect by applying argon gas in case simultaneously, first wafer is placed on high-temperature zone temperature to be controlled about 1700-1900 degree, treat that chip temperature is in about this district time about 20-60 minute, then wafer is moved to rapidly the relatively low region of temperature, about this warm area temperature is set in 1400-1500 degree, at the about 30-60 minute of this warm area Time constant, then wafer is moved more cold zone, control temperature greatly about less than 1500 until temperature reduce room temperature, by the intrinsic point defects concentration that can increase in carborundum crystals of lowering the temperature rapidly, thus obtain semi-insulating effect, wherein the intrinsic point defects concentration of semi-insulating crystal will be enough to the involuntary shallow donor of doping formation and the concentration difference of shallow acceptor in compensated silicon carbide crystal, thus guarantee the semi of wafer, for the manufacture of the substrate material of microwave high-power component.
The point defect concentration meeting the semi insulating silicon carbide silicon materials of the substrate needs of microwave power device does not have strict quantity limitation, most importantly require that point defect concentration exceedes the absolute value of the difference of shallow donor and shallow acceptor concentration, semi-insulated like this characteristic just possesses.What the mode (mixing vanadium) usually by deliberately adulterating also can obtain a kind of semi-insulating effect is mix vanadium semi-insulating silicon carbide crystalloid.
Growth system of the present invention is under ultrahigh vacuum(HHV), and vacuum is approximately to 1.5 × 10-6mabr.The graphite material used and powder are all high-purity materials, there is a small amount of impurity unavoidably, such as, N in environment in growth system, B in graphite material, these impurity can enter into crystal, but background impurity concn is the smaller the better, concentration all at 8.5 × 1017cm-3, preferably 2.5 × 1017cm-3.
Claims (2)
1. the high-purity semi-insulating silicon carbide crystalloid growing apparatus of a non-impurity-doped element, comprise high purity graphite crucible (2), the outer side of high purity graphite crucible (2) is provided with graphite felt thermal insulation layer (7), graphite felt thermal insulation layer (7) is respectively arranged with lower thermometer hole (8) and upper thermometer hole (9), it is characterized in that, the inner cavity top of high purity graphite crucible (2) is provided with graphite support (1), graphite support (1) is provided with seed crystal (4), carborundum crystals (5) after seed crystal (4) is provided with growth, in the chamber of high purity graphite crucible (2), bottom is provided with SiC highly pure powder (3), aperture (6) is provided with between graphite support (1) and the interior chamber inner sidewall of high purity graphite crucible (2).
2. the high-purity semi-insulating silicon carbide crystalloid growing apparatus of a kind of non-impurity-doped element according to claim 1, it is characterized in that, distance between the end face of SiC highly pure powder (3) and the bottom surface of seed crystal (4) is 50-60 millimeter, and the diameter of lower thermometer hole (8) and the diameter of upper thermometer hole (9) are 10-20 millimeter.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111647945A (en) * | 2018-05-18 | 2020-09-11 | 北京华进创威电子有限公司 | Preparation method of aluminum nitride crystal |
| CN113136622A (en) * | 2021-04-22 | 2021-07-20 | 中国电子科技集团公司第四十六研究所 | PVT method airflow-oriented silicon carbide single crystal growth device and using method |
| CN114657632A (en) * | 2022-02-24 | 2022-06-24 | 国宏中宇科技发展有限公司 | Tantalum structure, temperature measuring hole structure, crucible assembly and temperature measuring hole anti-blocking method |
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| JPH0412096A (en) * | 1990-04-26 | 1992-01-16 | Nippon Steel Corp | Method for growing 6h-type and 4h-type silicon carbide single crystal |
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- 2015-12-22 CN CN201510972097.7A patent/CN105420813A/en active Pending
Patent Citations (5)
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| JPH0412096A (en) * | 1990-04-26 | 1992-01-16 | Nippon Steel Corp | Method for growing 6h-type and 4h-type silicon carbide single crystal |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111647945A (en) * | 2018-05-18 | 2020-09-11 | 北京华进创威电子有限公司 | Preparation method of aluminum nitride crystal |
| CN113136622A (en) * | 2021-04-22 | 2021-07-20 | 中国电子科技集团公司第四十六研究所 | PVT method airflow-oriented silicon carbide single crystal growth device and using method |
| CN114657632A (en) * | 2022-02-24 | 2022-06-24 | 国宏中宇科技发展有限公司 | Tantalum structure, temperature measuring hole structure, crucible assembly and temperature measuring hole anti-blocking method |
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