CN113957541B - Seed crystal high-temperature bonding equipment and method for aluminum nitride crystal growth - Google Patents
Seed crystal high-temperature bonding equipment and method for aluminum nitride crystal growth Download PDFInfo
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- CN113957541B CN113957541B CN202010701354.4A CN202010701354A CN113957541B CN 113957541 B CN113957541 B CN 113957541B CN 202010701354 A CN202010701354 A CN 202010701354A CN 113957541 B CN113957541 B CN 113957541B
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- C—CHEMISTRY; METALLURGY
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- 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
- C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
- C30B33/06—Joining of crystals
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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
- C30B29/38—Nitrides
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Abstract
The invention discloses seed crystal high-temperature bonding equipment and a seed crystal high-temperature bonding method for aluminum nitride crystal growth, wherein the seed crystal high-temperature bonding equipment comprises a seed crystal, a crucible, an aluminum nitride crystal growth furnace, mechanical polishing and chemical cleaning equipment and a special heating and pressurizing device; pretreating the surface of the crucible cover and the back of the seed crystal, and placing the seed crystal on the crucible cover; placing the crucible cover on a sample table of a heating and pressurizing device; a sacrificial wafer with an unpolished surface is placed on the front surface of the seed crystal in advance, and the crucible cover and the seed crystal are pressurized; heating and preserving heat; then slowly cooling and filling nitrogen into the heating chamber to normal pressure, and slowly unloading the pressure transmission device on the sacrificial wafer; covering the bonded seed crystal and crucible in an aluminum nitride crystal growth furnace for high-temperature shaping; thereby obtaining the bonded aluminum nitride seed crystal. The invention can improve the growth quality of the aluminum nitride single crystal, has simple working procedures and is beneficial to realizing the preparation of the aluminum nitride single crystal with low cost.
Description
Technical Field
The patent relates to a semiconductor manufacturing device and a process, in particular to a novel method and equipment for high-temperature bonding of seed crystals for growth of aluminum nitride crystals.
Background
Aluminum nitride materials have been widely used in high temperature, high frequency, high power and radiation resistant devices due to their excellent properties such as high thermal conductivity and high breakdown field strength, and the research on aluminum nitride single crystal materials has become a research hotspot in the semiconductor field. The aluminum nitride single crystal is mainly prepared by adopting a Physical Vapor Transport (PVT) method, the bottom of a crucible required for growth is generally set to be a high-temperature region by utilizing the difference between a heat-insulating layer and the position of the crucible, the top of the crucible is set to be a low-temperature region, and raw material gas evaporated in the high-temperature region is artificially transported to the low-temperature region under the action of a temperature gradient to grow into crystals. The following two methods are currently used for crystal growth: firstly, the AlN crystal with better millimeter-grade quality is obtained by adopting a spontaneous nucleation method. Then the small AlN crystals with spontaneous nucleation are taken as seed crystals, and are expanded to grow by adopting a specially designed crucible, and a large-size AlN crystal is obtained by multiple iterations; and secondly, siC and other substrates are used as seed crystals, and an AlN layer is deposited by heteroepitaxy, so that the obtained crystals are poor in quality. And after the SiC layer is removed, the AlN layer is used as seed crystal for multiple times of iteration homoepitaxy, and the AlN single crystal substrate with optimized quality is obtained. Both methods require the attachment of the cut seed to the crucible cover for subsequent homoepitaxial growth. Therefore, the seed crystal bonding technology is one of the key technologies for growing the AlN single crystal by the PVT method, and the seed crystal and the crucible cover can still be tightly attached and cannot be partially or completely separated in the growth process of the AlN single crystal at the high temperature of more than 2000 ℃.
The seed crystal bonding technology commonly used at present can be roughly divided into two types, wherein the first type adopts various high-temperature adhesives, including carbon-based adhesives, ceramic adhesives and the like for bonding; the second main category is to design various clamps to clamp the seed crystal to the crucible cover. The first major technology has the main problems that (1) the AlN single crystal growth needs high temperature of more than 2000 ℃, the common commercial high-temperature binder basically does not have the capacity of resisting the high temperature, and a small number of binders meeting the requirement are extremely expensive and are limited to import; (2) Carbon-based or ceramic high-temperature adhesives contain impurity elements, and often enter crystals in a defect mode to influence the quality and optical performance of single crystals; (3) The existence of air holes is difficult to avoid in the bonding and curing process, so that small temperature gradients in the radial direction and the axial direction occur, and the quality of subsequently grown crystals is poor. However, the second major technique firstly loses part of the seed crystal surface, and more seriously, the seed crystal and the crucible cover are difficult to be in close contact at high temperature due to the tolerance fit of the fixture and the difference of the thermal expansion coefficients, so that the temperature gradient is easily formed in the radial direction and the axial direction, the quality of the crystal is deteriorated, and the single crystallinity is reduced.
Therefore, the aluminum nitride crystal growth has a plurality of problems when being bonded with the seed crystal, so that a new method for bonding the seed crystal used for the aluminum nitride crystal growth is urgently needed.
Disclosure of Invention
In order to overcome the defects of the existing seed crystal bonding technology, the invention provides a novel method for bonding seed crystals used for aluminum nitride crystal growth at high temperature and seed crystal high-temperature bonding equipment, which can improve the growth quality of aluminum nitride single crystals, have simple working procedures and are beneficial to realizing the preparation of the aluminum nitride single crystals at low cost.
The crucible cover and the clean and flat polished surface of the seed crystal which are subjected to flat polishing are mutually closely contacted under certain vacuum and pressure conditions, are kept for a long time at proper temperature, and the seed crystal and the crucible cover are bonded together by utilizing the mutual diffusion of molecules among closely contacted substances. The invention has simple working procedure, does not need to use high-temperature adhesive and fixture, has tight interface connection between the seed crystal and the crucible cover, has no clearance, holes and impurities at high temperature, and is beneficial to stabilizing the stability of the thermal field at the seed crystal, thereby improving the growth quality of the single crystal. The method is simple, is beneficial to realizing the preparation of the aluminum nitride single crystal with low cost, and is a novel device and a method for bonding seed crystals used for the growth of the aluminum nitride crystal.
The technical scheme provided by the invention is as follows:
a seed crystal high-temperature bonding device for aluminum nitride crystal growth comprises: the seed crystal for aluminum nitride growth, the crucible for crystal growth, the aluminum nitride crystal growth furnace, mechanical polishing and chemical cleaning equipment and a special heating and pressurizing device (shown in figure 1). The seed crystal and the crucible cover are used for bonding to grow the aluminum nitride crystal; the mechanical polishing equipment and the chemical cleaning equipment are used for polishing and cleaning the seed crystal and the crucible cover; the special heating and pressurizing device is used for bonding the seed crystal and the crucible cover for low-temperature shaping; the aluminum nitride crystal growth furnace is used for bonding the seed crystal and the crucible cover for high-temperature shaping. The special heating and pressurizing device comprises an air cylinder, a vacuum device, a heating resistance wire, a heat-preservation asbestos layer, a stainless steel shell, a sample table, a pressure hammer and a pressure transmission device. The heating resistance wire and the heat-insulating layer are used for heating and heat-insulating to meet the temperature requirement; the air cylinder, the pressure transmission device and the pressure hammer are used for providing pressure; the sample platform is used for loading the sample. The outer side of the special heating and pressurizing device is provided with a stainless steel shell; the side surface is provided with a vacuum device; the inside of the stainless steel shell is provided with a heating resistance wire and a heat preservation asbestos layer; the air cylinder is arranged above the special heating and pressurizing device and connected with the pressure transmission device and the pressure hammer, and the sample table is arranged right below the special heating and pressurizing device.
In the above apparatus for bonding seed crystals for aluminum nitride crystal growth, further:
when the crucible cover is pretreated by mechanical polishing, chemical cleaning and the like, the crucible cover can be made of tungsten W, tantalum Ta or tantalum carbide TaC and other various materials, and the requirements are that the surface roughness Ra is less than 1.6 mu m and the flatness tolerance grade is less than 4 grade. When the back of the seed crystal is pretreated by chemical polishing, chemical cleaning and the like, the seed crystal material can be selected from various materials such as aluminum nitride (AlN), silicon carbide (SiC), boron Nitride (BN) or a pairwise composite substrate thereof, and the surface roughness RMS of the seed crystal material on an atomic force microscope is required to be less than 10nm;
when the polished seed crystal is placed on the crucible cover, the type of the sacrificial wafer can be selected from various materials such as sapphire, aluminum carbide, boron nitride and the like, and the ultimate vacuum degree is required when the polished seed crystal is vacuumized to the ultimate vacuum degree<10 -1 Pa. After the ultimate vacuum is reached, the pressure transmission device is operated to pressurize to a certain pressure P, wherein P =1-20kg;
after the vacuum degree and the pressure reach set values, the temperature is increased to a proper temperature T and kept for a period of time T, wherein T =50-900 ℃ and T =4-100h.
The invention also provides a novel seed crystal bonding method for aluminum nitride crystal growth, which uses the device/equipment for bonding the seed crystal used for the aluminum nitride crystal growth, and the specific steps for bonding the aluminum nitride seed crystal are as follows:
1) And (3) performing pretreatment such as mechanical polishing, chemical cleaning and the like on the surface of the crucible cover, simultaneously performing pretreatment such as chemical polishing, chemical cleaning and the like on the back of the seed crystal, and placing the polished seed crystal on the crucible cover.
2) The crucible cover is placed on a sample table of the special heating and pressurizing device; a sacrificial wafer with an unpolished surface is placed on the front surface of a seed crystal in advance, a pressure transmission device is operated, the sacrificial wafer is slowly pressed down, and the vacuum pumping is started to the limit vacuum. And after the ultimate vacuum is reached, the pressure rod is operated to pressurize the crucible cover and the seed crystal.
3) After the vacuum degree and the pressure reach set values (the vacuum degree reaches below 0.1Pa and the pressure reaches above 1 kg), the temperature is raised to be above 50 ℃ and the temperature is kept for a period of time, so that a molecular-level or atomic-level mutual solid diffusion interface is obtained between the crucible cover and the seed crystal. And finally, slowly cooling to room temperature after the heat preservation time is up, filling nitrogen into the heating chamber to normal pressure, slowly unloading the pressure transmission device on the sacrificial wafer to 0, then lifting, opening the furnace door, and taking out the bonded seed crystal and the crucible cover.
4) And placing the bonded seed crystal and the crucible cover at the bottom of the crucible in the aluminum nitride crystal growth furnace, and regulating and controlling the temperature gradient by changing the position of the crucible to perform high-temperature shaping in the aluminum nitride crystal growth furnace. Thereby obtaining the bonded aluminum nitride seed crystal.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a novel method for bonding seed crystals used for aluminum nitride crystal growth, which changes a bonding method to bond the seed crystals. The method can avoid the reduction of the growth quality of the aluminum nitride crystal caused by the use problem of the adhesive glue in the traditional bonding method. Meanwhile, the invention can improve the quality of seed crystal bonding, reduce the cost and increase the usable area of the single crystal. And the method is simple and is beneficial to realizing the preparation of the aluminum nitride single crystal with low cost.
Drawings
FIG. 1 is a schematic structural view of a special heating and pressurizing device for seed crystal bonding in the invention,
the device comprises a cylinder 1, a heating resistance wire 2, an asbestos heat insulation layer 3, a stainless steel shell 4, a high vacuum pumping device 5, a seed crystal 6, a sample table 7, a pressure transmission rod 8, a pressure hammer 9, a sacrificial wafer 10 and a crucible cover 10.
FIG. 2 is a schematic structural view of an apparatus for performing seed crystal bonding high-temperature curing in accordance with the present invention,
wherein, the heating and heat preservation device of the 11-aluminum nitride crystal growth furnace comprises a 12-crucible, a 5-seed crystal and a 10-crucible cover.
FIG. 3 is a flow chart of a method for bonding seeds for aluminum nitride crystal growth provided by the present invention.
Detailed Description
The invention will be further described by way of examples, without in any way limiting the scope of the invention, with reference to the accompanying drawings.
The invention provides a novel method for bonding seed crystals used for growing aluminum nitride crystals.
FIG. 1 is a schematic structural view of a heating and pressurizing apparatus dedicated for seed crystal bonding; the device comprises a cylinder 1, a heating resistance wire and an asbestos heat-insulating layer 2, a stainless steel shell 3, a high-vacuum pumping device 4, seed crystals 5, a sample table 6, a pressure transmission rod 7, a pressure hammer 8, a sacrificial wafer 9 and a crucible cover 10. Wherein:
(1) When the seed crystal is placed on the crucible cover, the type of the sacrificial wafer can be selected from various materials such as sapphire, aluminum carbide, boron nitride and the like, and the sacrificial wafer is placed in a special heating device, and the ultimate vacuum degree is required when the sacrificial wafer is vacuumized to the ultimate vacuum degree<10 -1 Pa. After the ultimate vacuum is reached, operating the pressure rod to pressurize to a certain pressure P, wherein P =1-20kg;
(2) After the vacuum degree and the pressure reach set values, the temperature is increased to a proper temperature T and kept for a period of time T, wherein T =50-900 ℃ and T =4-100h.
FIG. 2 is a structural view of an apparatus for high-temperature setting of seed crystal bonding according to the present invention; wherein 11 is a heating and heat-preserving device of the aluminum nitride crystal growth furnace, 12 is a large crucible, 5 is seed crystal, and 10 is a crucible cover. Wherein:
(1) The furnace body structure of the aluminum nitride crystal growth furnace is arranged on the outermost side, multiple sections of graphite heat-insulating layers or tungsten heat-insulating screens and other heat-insulating materials are placed in the furnace body structure, the heating temperature which can be achieved can be above 2000 ℃, the position of a crucible in the crystal growth furnace can be changed, and the temperature gradient can be conveniently regulated and controlled in the high-temperature bonding process.
(2) The crucible is placed in the heat insulation material, and the material of the crucible is the same as the material of the crucible cover and is matched with the material of the crucible cover in size.
In specific implementation, the step of bonding the seed crystal for the aluminum nitride crystal growth by using the device (shown in figures 1 and 2) comprises the following steps:
(1) And (3) carrying out pretreatment such as mechanical polishing, chemical cleaning and the like on the crucible cover, and simultaneously carrying out pretreatment such as chemical polishing, chemical cleaning and the like on the back of the seed crystal, and contacting the polished surface and the polished back of the seed crystal with each other after the requirements are met.
(2) The crucible cover is placed on a sample table of the special heating device; a sacrificial wafer with an unpolished surface is placed on the front surface of the seed crystal in advance, the pressure transmission device is operated to slowly drop the pressure on the sacrificial wafer, and the vacuum pumping is started to the limit vacuum. After reaching the limit vacuum, the pressure transmission device is operated to pressurize to a certain pressure.
(3) After the vacuum degree and the pressure reach set values, the temperature is raised to a proper temperature and kept for a period of time, so that a molecular (atomic) level mutual solid diffusion interface is obtained between the crucible cover and the seed crystal. And finally, slowly cooling to room temperature after the heat preservation time is up, filling nitrogen into the heating chamber to normal pressure, slowly unloading the pressure rod on the sacrificial sheet to 0, then lifting, opening the furnace door, and taking out the seed crystal/crucible cover.
(4) And (3) placing the bonded seed crystal and the crucible cover into the bottom of a crucible in the aluminum nitride crystal growth furnace, and regulating and controlling the temperature gradient by changing the position of the crucible to perform high-temperature shaping in the aluminum nitride crystal growth furnace. Thereby obtaining the bonded aluminum nitride seed crystal.
The following schemes are examples of the seed crystals used for the growth of aluminum nitride crystals obtained by the above method, and the specific conditions for the implementation are shown in the following tables.
TABLE 1 examples of different methods employed for bonding seed crystals for aluminum nitride crystal growth
The method comprises the following specific steps:
the first embodiment is as follows: and bonding the silicon carbide seed crystals in an induction heating furnace.
The preparation method comprises the following specific steps:
(1) Selecting a tantalum carbide crucible cover and a silicon carbide seed crystal with proper sizes, and carrying out pretreatment such as mechanical polishing, chemical cleaning and the like on the crucible cover, wherein the Ra value of the surface roughness is required to be 1.5 mu m, and the planeness tolerance grade is 3 grade. Meanwhile, the back of the seed crystal is pretreated by chemical polishing, chemical cleaning and the like, and the RMS value of the surface roughness of the atomic microscope is required to be 9nm.
(2) Placing seed crystal on a crucible cover, placing the crucible cover on a sample platform of a special heating and pressurizing device, placing a sapphire wafer with unpolished surface on the front surface of the seed crystal in advance, operating a pressure transmission device to slowly drop and press the sapphire wafer, starting vacuumizing to a limit vacuum degree<10 -1 Pa. After reaching the limit vacuum, the pressure transmission is operated to pressurize to a certain pressure P, P =5kg.
(3) After the vacuum degree and the pressure reach set values, the temperature is raised to 200 ℃ and kept for 90 hours, so that a molecular (atomic) level mutual solid diffusion interface is obtained between the crucible cover and the seed crystal. And finally, slowly cooling to room temperature after the heat preservation time is up, filling nitrogen into the heating chamber to normal pressure, slowly unloading the pressure rod on the sacrificial sheet to 0, then lifting, opening the furnace door, and taking out the seed crystal/crucible cover. It is put into an aluminum nitride crystal growth furnace.
(5) Raising the temperature of the induction heating type aluminum nitride crystal growth furnace to 2000 ℃, filling nitrogen into the furnace, ensuring the pressure to be 500Torr, and adjusting the position of the crucible to ensure that the temperature difference between the seed crystal and the crucible cover is 20 ℃. Heating at high temperature for 50h, and taking out to obtain the bonded silicon carbide seed crystal.
Example two: and adhering the aluminum nitride seed crystal in an induction heating furnace.
The specific preparation process is as follows:
(1) Selecting a tantalum carbide crucible cover and a silicon carbide seed crystal with proper sizes, and carrying out pretreatment such as mechanical polishing, chemical cleaning and the like on the crucible cover, wherein the Ra value of the surface roughness is required to be 1.3 mu m, and the flatness tolerance grade is 3 grade. Meanwhile, the back of the seed crystal is pretreated by chemical polishing, chemical cleaning and the like, and the RMS value of the surface roughness of the atomic microscope is required to be 7nm.
(2) Placing seed crystal on a crucible cover, placing the crucible cover on a sample platform of a special heating and pressurizing device, placing a boron nitride wafer with unpolished surface on the front surface of the seed crystal in advance, operating a pressure transmission device to slowly drop and press the boron nitride wafer, starting vacuumizing to a limit vacuum degree<10 -1 Pa. After reaching the limit vacuum, the pressure transmission is operated to pressurize to a certain pressure P, P =1kg.
(3) After the vacuum degree and the pressure reach set values, the temperature is raised to 600 ℃ and kept for 50h, so that a molecular (atomic) level mutual solid diffusion interface is obtained between the crucible cover and the seed crystal. And finally, slowly cooling to room temperature after the heat preservation time is up, filling nitrogen into the heating chamber to normal pressure, slowly unloading the pressure of the pressure transmission device on the sacrificial sheet to 0, then lifting, opening the furnace door and taking out the seed crystal/crucible cover. It is put into an aluminum nitride crystal growth furnace.
(4) Raising the temperature of an induction heating type aluminum nitride crystal growth furnace to 2000 ℃, filling argon into the furnace, ensuring the pressure to be 600Torr, and adjusting the position of a crucible to ensure that the temperature difference between seed crystals and a crucible cover is 20 ℃. And heating at high temperature for 75h, and taking out to obtain the bonded aluminum nitride seed crystal.
Example three: and adhering the aluminum nitride seed crystal in a resistance heating furnace.
The specific preparation process is as follows:
(1) Selecting a tantalum carbide crucible cover and a silicon carbide seed crystal with proper sizes, and carrying out pretreatment such as mechanical polishing, chemical cleaning and the like on the crucible cover, wherein the Ra value of the surface roughness is required to be 1.2 mu m, and the flatness tolerance grade is 3 grade. Meanwhile, the back of the seed crystal is pretreated by chemical polishing, chemical cleaning and the like, and the RMS value of the surface roughness of the atomic microscope is required to be 5nm.
(2) Placing seed crystal on a crucible cover, placing the crucible cover on a sample platform of a special heating and pressurizing device, placing a sapphire wafer with unpolished surface on the front surface of the seed crystal in advance, operating a pressure transmission device to slowly drop and press the sapphire wafer, starting vacuumizing to a limit vacuum degree<10 -1 Pa. After reaching the limit vacuum, the pressure transmission is operated to pressurize to a certain pressure P, P =20kg.
(3) After the vacuum degree and the pressure reach set values, the temperature is raised to 900 ℃ and kept for 10 hours, so that a molecular (atomic) level mutual solid diffusion interface is obtained between the crucible cover and the seed crystal. And finally, slowly cooling to room temperature after the heat preservation time is up, filling nitrogen into the heating chamber to normal pressure, slowly unloading the pressure of the pressure transmission device on the sacrificial sheet to 0, then lifting, opening the furnace door and taking out the seed crystal/crucible cover. It is put into an aluminum nitride crystal growth furnace.
(4) The temperature of the resistance heating type aluminum nitride crystal growth furnace is raised to 2000 ℃, nitrogen and argon mixed gas is filled into the resistance heating type aluminum nitride crystal growth furnace, the pressure is ensured to be 700Torr, and the position of the crucible is adjusted, so that the temperature difference between the seed crystal and the crucible cover is 30 ℃. Heating at high temperature for 100h, and taking out to obtain the bonded aluminum nitride seed crystal.
It is noted that the disclosed embodiments are intended to aid in further understanding of the invention, but those skilled in the art will appreciate that: various substitutions and modifications are possible without departing from the spirit and scope of the invention and appended claims. Therefore, the invention should not be limited to the embodiments disclosed, but the scope of the invention is defined by the appended claims.
Claims (9)
1. A high-temperature bonding method of seed crystal for aluminum nitride crystal growth is characterized in that a high-temperature adhesive is not needed, the seed crystal is tightly connected with an interface of a crucible cover, and the interface has no clearance, holes and impurities at high temperature; the method comprises the following steps:
1) Performing mechanical polishing and chemical cleaning pretreatment on the surface of the crucible cover, and simultaneously performing chemical polishing and chemical cleaning pretreatment on the back of the seed crystal; placing the treated seed crystal on a crucible cover;
wherein the crucible cover material is tungsten W, tantalum Ta or tantalum carbide TaC; surface roughness Ra <1.6 μm, flatness tolerance class < 4; the seed crystal material is aluminum nitride (AlN), silicon carbide (SiC), boron Nitride (BN) or a pairwise composite substrate material, and the surface roughness RMS of the seed crystal material on an atomic force microscope is less than 10nm;
2) Placing the crucible cover on a sample table of a heating and pressurizing device; a sacrificial wafer with an unpolished surface is placed on the front surface of the seed crystal in advance, a pressure transmission device of a heating and pressurizing device is operated to slowly descend and press the sacrificial wafer, and the sacrificial wafer is vacuumized to the limit vacuum; after reaching the limit vacuum, operating a pressure transmission device to pressurize the crucible cover and the seed crystal;
3) After the vacuum degree and the pressure reach set values, heating and preserving heat for a period of time to obtain a molecular-level or atomic-level mutual solid diffusion interface between the crucible cover and the seed crystal; after the vacuum degree reaches below 0.1Pa and the pressure reaches above 1kg, heating to a temperature above 50 ℃ and preserving the heat for 4 to 100h; then slowly cooling to room temperature, filling nitrogen into the heating chamber to normal pressure, slowly unloading the pressure transmission device on the sacrificial wafer to 0, then lifting, and taking out the bonded seed crystal and crucible cover;
4) Placing the bonded seed crystal and the crucible cover at the bottom of a crucible in an aluminum nitride crystal growth furnace, and regulating and controlling the temperature gradient by changing the position of the crucible to carry out high-temperature shaping in the aluminum nitride crystal growth furnace;
thereby obtaining the bonded aluminum nitride seed crystal.
2. A seed crystal high temperature bonding method for aluminum nitride crystal growth according to claim 1, wherein the sacrificial wafer is a plurality of materials of sapphire, aluminum carbide and boron nitride.
3. A seed crystal high-temperature bonding method for aluminum nitride crystal growth according to claim 1, wherein a limit vacuum degree is required when a vacuum is pumped to the limit vacuum degree<10 -1 Pa。
4. A seed crystal high-temperature bonding method for aluminum nitride crystal growth according to claim 3, wherein the pressure transmission means is operated to pressurize to a pressure P of 1 to 20kg after reaching the ultimate vacuum.
5. A seed crystal high-temperature bonding method for aluminum nitride crystal growth according to claim 4, wherein the temperature is raised to a temperature T =50-900 after the vacuum degree and the pressure are reached o C。
6. A seed crystal high-temperature bonding method for aluminum nitride crystal growth according to claim 1, wherein said method uses a seed crystal high-temperature bonding apparatus for aluminum nitride crystal growth, comprising: seed crystal for growing aluminum nitride, crucible for growing crystal, aluminum nitride crystal growing furnace, mechanical polishing and chemical cleaning equipment and special heating and pressurizing device;
the seed crystal and the crucible cover are used for bonding to grow the aluminum nitride crystal; the mechanical polishing equipment and the chemical cleaning equipment are used for polishing and cleaning the seed crystal and the crucible cover; the special heating and pressurizing device is used for bonding the seed crystal and the crucible cover for low-temperature shaping; the aluminum nitride crystal growth furnace is used for bonding the seed crystal and the crucible cover for high-temperature shaping.
7. A seed crystal high-temperature bonding method for aluminum nitride crystal growth according to claim 6,
the special heating and pressurizing device comprises an air cylinder, a vacuum device, a heating resistance wire, a heat-preservation asbestos layer, a stainless steel shell, a sample table, a pressure hammer and a pressure transmission device; the heating resistance wire and the heat-insulating layer are used for heating and heat-insulating; the air cylinder, the pressure transmission device and the pressure hammer are used for providing pressure; the sample stage is used for loading the sample.
8. A seed crystal high-temperature bonding method for aluminum nitride crystal growth according to claim 7, wherein a vacuum device is provided on the side of the stainless steel housing of the special heating and pressurizing device; the inside of the stainless steel shell is provided with a heating resistance wire and a heat preservation asbestos layer.
9. A seed crystal high-temperature bonding method for aluminum nitride crystal growth according to claim 7, wherein a cylinder is positioned above the special heating and pressurizing device, and the cylinder is connected with a pressure transmission device and a pressure hammer; the sample stage is positioned under the special heating and pressurizing device.
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| CN202157144U (en) * | 2011-06-21 | 2012-03-07 | 中国电子科技集团公司第二研究所 | Automatic control device for splicing of silicon carbide seed crystals |
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| CN107829134A (en) * | 2017-11-22 | 2018-03-23 | 北京大学 | A kind of aluminum-nitride single crystal grower and method without seed crystal adhesive technology |
| CN108624954A (en) * | 2018-03-29 | 2018-10-09 | 苏州奥趋光电技术有限公司 | A kind of method of isoepitaxial growth aluminum-nitride single crystal |
| CN108468089A (en) * | 2018-05-16 | 2018-08-31 | 福建北电新材料科技有限公司 | A kind of technique of Efficient high-temperature solidification silicon carbide seed |
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