CN114752999A - Equipment and method for preparing crystal - Google Patents

Equipment and method for preparing crystal Download PDF

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Publication number
CN114752999A
CN114752999A CN202210329910.9A CN202210329910A CN114752999A CN 114752999 A CN114752999 A CN 114752999A CN 202210329910 A CN202210329910 A CN 202210329910A CN 114752999 A CN114752999 A CN 114752999A
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temperature
growth chamber
heat
growth
length
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CN114752999B (en
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覃佐燕
武红磊
李文良
金雷
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Shenzhen University
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Shenzhen University
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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
    • 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
    • C30B23/002—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
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/40—AIIIBV compounds wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi
    • C30B29/403—AIII-nitrides
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Abstract

The invention provides equipment and a method for preparing crystals, which comprise the following steps: the equipment comprises an equipment main body, a heat source fixed on the equipment main body, a growth chamber fixed on the equipment main body and positioned in the heat source, and at least two layers of temperature regulating members fixed on the growth chamber and positioned between the heat source and the growth chamber, wherein the growth chamber is provided with a containing cavity for containing the source material, one end of the temperature regulating member of each temperature regulating member is fixed on the growth chamber, the other end of the temperature regulating member of each temperature regulating member is arranged at intervals of the heat source, the lengths of the temperature regulating members of the same layer of temperature regulating member are equal, the lengths of the temperature regulating members of the adjacent layers of temperature regulating members are unequal, and heat generated by the heat source is transmitted to the temperature regulating members and is transmitted to the growth chamber by the temperature regulating members. The lengths of the temperature adjusting parts of the same layer of temperature adjusting part group are equal, the lengths of the temperature adjusting parts of the adjacent layer of temperature adjusting part group are unequal, and the temperature distribution of the temperature field of the growth chamber can be changed by adjusting the lengths of the temperature adjusting parts, so that the growth chamber can provide a temperature gradient suitable for crystal growth.

Description

Equipment and method for preparing crystal
Technical Field
The invention belongs to the technical field of crystal growth equipment, and particularly relates to equipment and a method for preparing crystals.
Background
The aluminum nitride has ultra-wide band gap (6.2eV), high breakdown field strength (11.7 × 106V cm)-1) High heat, high heatConductivity (measured value 3.16W cm)-1·K-1) The material has excellent properties of radiation resistance, acid and alkali resistance, high stability and the like, and can be used for preparing devices such as deep ultraviolet LEDs, LDs, high-power electrons, nuclear reactor vibration detection and the like. In addition, aluminum nitride (AlN) has small lattice mismatch and thermal mismatch with gallium nitride (GaN) and aluminum gallium nitride (AlGaN), and is an ideal substrate material for GaN and AlGaN as functional layer devices. Therefore, the preparation of the AlN single crystal has great significance for the preparation of photoelectric and electronic devices. At present, a Physical Vapor Transport (PVT) method is the most ideal method for preparing the AlN single crystal substrate.
The current equipment for AlN crystal growth is mainly an induction heating graphite system furnace and a resistance heating metal furnace, both of which are set to a growth temperature of AlN crystal by giving a sufficiently high power. In order to achieve a temperature difference suitable for AlN crystal growth in the related art, an auxiliary heater is generally used to adjust the temperature gradient. The auxiliary heater increases the preparation difficulty of crystal growth equipment in the aspects of design, installation, maintenance and the like, and simultaneously increases the cost of the equipment; on the other hand, due to the space limitation in the cavity, the auxiliary heater can only be designed into a plane structure with a simpler structure, the heater with the structure has the characteristics of low resistance and low emissivity, and only the local heating at the top of the growth chamber can be realized, so that the temperature gradient suitable for crystal growth cannot be met.
Disclosure of Invention
The invention aims to provide equipment and a method for preparing crystals, and aims to solve the problem that the temperature gradient suitable for crystal growth of the equipment for preparing crystals in the related art cannot be met.
In order to solve the above technical problems, a first aspect of the present invention provides an apparatus for producing a crystal, comprising: the equipment main part, be fixed in the heat source of equipment main part, be fixed in the equipment main part just is located growth chamber in the heat source and be fixed in the growth chamber just is located the heat source with at least two-layer temperature regulating member group between the growth chamber, the growth chamber has the chamber that holds that is used for holding the source material, the one end of the temperature regulating member of temperature regulating member group is fixed in the growth chamber, the other end interval the heat source sets up, and same layer the length of the temperature regulating member of temperature regulating member group equals, and the adjacent layer the length of the temperature regulating member of temperature regulating member group is unequal, the heat conduction that the heat source produced extremely the temperature regulating member and quilt adjust the temperature the piece and conduct extremely the growth chamber.
Preferably, the lengths of the temperature adjusting parts are distributed in a gradient manner along the length extending direction of the accommodating cavity.
Preferably, the growth chamber has a bottom and a top opposite to the bottom, the length of the temperature adjusting member closer to the bottom of the growth chamber in the adjacent temperature adjusting member layer is greater than that of the temperature adjusting member farther from the bottom of the growth chamber, and each layer of the temperature adjusting member group has at least four temperature adjusting members arranged at intervals.
Preferably, the temperature adjusting member includes a heat conduction arm fixed to a side of the growth chamber away from the accommodating cavity and a heat receiving unit fixed to an end of the heat conduction arm away from the growth chamber, a length of each of the heat conduction arms decreases in sequence along a length extending direction of the accommodating cavity, a gap is provided between the heat receiving unit and the heat source, a heat receiving area is provided on a side of the heat receiving unit close to the heat source, and a gap is provided between adjacent heat receiving units on the same layer.
Preferably, the joint of the heat conduction arm and the heated portion is arranged between two ends of the heated portion, the cross section of the heat conduction arm is of a rectangular structure or a trapezoid-like structure, and one side of the heated portion, which is close to the heat source, is an arc surface.
Preferably, the arc curvature of the cambered surface is 0cm-1-0.05cm-1And the roughness R of the cambered surfaceaGreater than 25.
Preferably, the length of the heat conducting arm ranges from 2mm to 35mm, and the thickness ranges from 0.1mm to 2.5 mm; the length of the heated part ranges from 2mm to 35mm, and the thickness ranges from 0.3mm to 2.5 mm.
Preferably, the material of the piece that adjusts the temperature includes tungsten, the surface of the piece that adjusts the temperature is equipped with the coating, the absorptivity of coating is greater than the absorptivity of tungsten, the thickness value range of coating is 500nm-200 um.
Preferably, at least two fixing rings are fixedly sleeved on the outer side of the growth chamber, each fixing ring is distributed along the length extending direction of the containing cavity, and each temperature adjusting piece is fixed to the fixing ring.
The second invention of the present invention provides a method for preparing a crystal, applied to the apparatus for preparing an aluminum nitride crystal as described above, comprising:
arranging at least two layers of temperature regulating element groups on the growth chamber according to the corresponding relation between the length of the temperature regulating element and the temperature of the growth chamber; the lengths of the temperature adjusting parts of the temperature adjusting part groups on the same layer are equal, the lengths of the temperature adjusting parts of the temperature adjusting part groups on the adjacent layers are unequal, and the longer the length of the temperature adjusting part group is, the stronger the heat absorbing capacity of the corresponding position of the growth chamber is;
placing source materials into the accommodating cavity of the growth chamber;
after the heat source generates heat and the heat is conducted to the growth chamber through the temperature adjusting piece, the actual temperature gradient of the growth chamber is the same as the target temperature gradient of crystal growth, and the source material absorbs the heat to sublimate and deposits at a low temperature to obtain the crystal.
Compared with the prior art, the equipment and the method for preparing the crystal have the advantages that: the heat generated by the heat source is conducted to the growth chamber through the temperature adjusting piece, and the longer the temperature adjusting piece is, the more heat is obtained at the position corresponding to the growth chamber, so that the higher the temperature at the position corresponding to the growth chamber is, and the temperature of the growth chamber is controlled by using the length of the temperature adjusting piece; the lengths of the temperature adjusting parts of the temperature adjusting part groups on the same layer are equal, the lengths of the temperature adjusting parts of the temperature adjusting part groups on the adjacent layers are unequal, and the temperature distribution of a temperature field of the growth chamber can be changed by adjusting the lengths of the temperature adjusting parts, so that the lengths of the temperature adjusting parts arranged along the length extension direction of the accommodating cavity are sequentially increased or decreased, and the growth chamber can be ensured to provide a temperature gradient suitable for crystal growth; simultaneously, compare in prior art the direct mode through radiation conduction of heat source with heat conduction to growing chamber, this application sets up the temperature regulating part on growing chamber and can promote the growing chamber and be applicable to the regional height of temperature field of crystal growth to increase the effective space that is suitable for crystal growth.
Drawings
FIG. 1 is a sectional view in the front view showing the longitudinal connection of a temperature-adjusting member in an apparatus for producing a crystal in example 1 of the present invention;
FIG. 2 is a sectional view in the top view of the longitudinal connection of a temperature-adjusting member in the apparatus for producing crystals in example 1 of the present invention;
FIG. 3 is a front sectional view showing a cross-sectional view of a temperature-adjusting member in an apparatus for producing a crystal in example 1 of the present invention;
FIG. 4 is a sectional view in the top view showing the lateral connection of a temperature-adjusting member in the apparatus for producing crystals in example 1 of the present invention;
FIG. 5 is a schematic view showing a coating layer of a temperature-adjusting member in an apparatus for producing a crystal according to example 1 of the present invention;
FIG. 6 is a schematic flow chart of a method for producing a crystal in example 2 of the present invention.
In the drawings, each reference numeral indicates: 1. a growth chamber; 11. an accommodating chamber; 2. a temperature adjusting member set; 21. a temperature adjustment member; 211. a heat conducting arm; 212. a heat receiving unit; 3. and (4) coating.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The basic growth principle of preparing AlN crystal by PVT method is that AlN source is sublimated at high temperature (more than 2200 ℃) in high temperature nitrogen environment, and is deposited at lower temperature to obtain AlN crystal, the influence of temperature and temperature difference on crystal in the process is very important, and various research groups at home and abroad make intensive research on the influence of temperature field on crystal growth, which is as follows:
the published PVT method seed crystal induced aluminum nitride crystal growth method (applied to seed PVT growth of AIN crystals) of crystal growth journal mentions that the appearance of aluminum nitride crystals at different temperatures will present different characteristics, and the temperature for growing the bulk single crystal needs to reach 2100-2250 ℃.
In the PVT method nano-scale to centimeter-scale AlN single crystal growth (PVT growth of AlN single crystals with the diameter from nano-to concentric-meter level) published in the proceedings set of Physics (Journal of Physics: Conference Series), it is pointed out that the anisotropy of crystal during the crystal growth has large difference due to the difference of growth temperature; with the continuous rise of temperature, AlN crystals from nano-scale to centimeter-scale can be obtained; besides the temperature, the control of the temperature difference is also indispensable in the crystal growth; the change of the temperature difference can directly regulate and control the supersaturation degree of the aluminum vapor in the growth process, and influences the growth rate, nucleation state and growth mode of the crystal.
Research on growth behavior of AlN single crystals is published in artificial crystal science reports that the temperature gradient has an important influence on the growth mode of AlN crystal at the nucleation stage, thereby influencing the quality of AlN crystal.
At present, in order to obtain high-quality AlN crystals, resistance heating metal furnaces are the mainstream equipment for AlN crystal growth in the future. The temperature of the growth zone of the resistance heating metal furnace can reach 2500 ℃. Reaching such high temperatures consumes a large amount of electric power, and the higher the temperature is, the larger the increase in power consumption is. The thermodynamics and kinetics of crystal growth show that the temperature gradient is the driving force for crystal growth, so that a completely positive temperature field is needed when the seed crystal induces and grows the AlN crystal. However, the heat source has the characteristics of high temperature in the middle and low temperature in the upper and lower parts, and the height of the temperature field area suitable for the growth of the AlN crystal only occupies 2/3 of the height of the accommodating cavity. Therefore, on the one hand, the effective crystal growth space of the crystal growth apparatus is shortened, and on the other hand, a temperature gradient suitable for crystal growth cannot be satisfied.
Example 1:
referring to fig. 1 and 2, in this embodiment, an apparatus for manufacturing a crystal includes: the equipment comprises an equipment main body, a heat source fixed on the equipment main body, a growth chamber 1 fixed on the equipment main body and located in the heat source, and at least two layers of temperature regulating members 2 fixed on the growth chamber 1 and located between the heat source and the growth chamber 1, wherein the growth chamber 1 is provided with a containing cavity 11 used for containing source materials, one end of each temperature regulating member 21 of each temperature regulating member 2 is fixed on the growth chamber 1, the other end of each temperature regulating member 21 is arranged at intervals of the heat source, the lengths of the temperature regulating members 21 of the same layer of temperature regulating member 2 are equal, the lengths of the temperature regulating members 21 are distributed in a gradient mode in the length extending direction of the containing cavity 11, and heat generated by the heat source is conducted to the temperature regulating members 21 and is conducted to the growth chamber 1 by the temperature regulating members 21. Because the heat generated by the heat source is conducted to the growth chamber 1 through the temperature adjusting part 21, the longer the temperature adjusting part 21 is, the more heat is obtained at the position corresponding to the growth chamber 1, so that the higher the temperature at the position corresponding to the growth chamber 1 is, and the temperature of the growth chamber 1 can be controlled by adjusting the length of the temperature adjusting part 21; the lengths of the temperature adjusting parts 21 of the temperature adjusting part group 2 on the same layer are equal, the lengths of the temperature adjusting parts 21 of the temperature adjusting part groups 2 on the adjacent layers are unequal, and the temperature distribution of the temperature field of the growth chamber 1 can be changed by adjusting the lengths of the temperature adjusting parts 21, so that the growth chamber 1 can provide a temperature gradient suitable for crystal growth; simultaneously, compare in prior art the direct mode through radiation conduction of heat source with heat conduction to growth chamber 1, this application sets up on growth chamber 1 and adjusts the temperature piece 21 and can promote growth chamber 1 and be applicable to the regional height of temperature field of crystal growth to increase the effective space that is suitable for crystal growth. It can be understood that the heat source conducts heat to the growth chamber 1 by means of conduction of radiation heat transfer, the radiation heat transfer is the main heat transfer mode in the crystal growth temperature field distribution, and the relationship between the radiation intensity and the distance is researched based on a differential method, so that the radiation intensity and the distance have the following relationship:
I∝d-0.893T4；
Wherein I is the radiation intensity, d is the distance, and T is the absolute temperature.
As can be seen from the above formula, the radiation intensity decreases with the increase of the distance, and the longer the temperature adjusting member 21 is, the shorter the distance between the heat source and the temperature adjusting member 21 is, the stronger the radiation intensity is, that is, the longer the temperature adjusting member 21 is, the more the heat source conducts to the growth chamber 1, and the higher the temperature of the corresponding position of the growth chamber 1.
Referring to fig. 1 and 2, in the present embodiment, the lengths of the temperature adjusting members 21 are distributed in a gradient manner along the length extending direction of the accommodating chamber 11. Specifically, the crystal is the aluminium nitride crystal, and the length of each piece 21 that adjusts the temperature on the length extending direction that holds chamber 11 is positive gradient distribution for the length of each piece 21 that adjusts the temperature that sets up along the length extending direction that holds chamber 11 reduces in proper order, guarantees that growth chamber 1 can provide the temperature for the growth of aluminium nitride crystal and be the temperature field that positive gradient distributes, is favorable to promoting the quality of the aluminium nitride crystal that the growth obtained. In other embodiments, the crystal may be a silicon carbide crystal or the like, as the actual need arises; the lengths of the temperature control elements 21 may be inversely graded or irregularly distributed along the longitudinal extension of the accommodating chamber 11.
Referring to fig. 1 and 2, in the present embodiment, the growth chamber 1 has a bottom and a top opposite to the bottom, the length of the temperature adjusting member 21 closer to the bottom of the growth chamber 1 in the adjacent temperature adjusting member 21 layers is greater than the length of the temperature adjusting member 21 farther from the bottom of the growth chamber 1, and each temperature adjusting member group 2 has at least four temperature adjusting members 21 arranged at intervals. Specifically, the growth chamber 1 can be a cylindrical crucible, the crucible is provided with an accommodating cavity 11 for placing the aluminum nitride crystal source, and the growth chamber 1 is of a cylindrical structure, so that the aluminum nitride crystal source can uniformly grow in the accommodating cavity 11; the heat source can be a cylindrical heater, a tungsten-molybdenum shielding layer is adopted for heat preservation, the temperature of a growth area in the heater can reach 2500 ℃, the growth chamber 1 is positioned in the cylindrical heater, and the temperature of the growth chamber 1 can reach 2500 ℃. The length of the temperature regulating piece 21 closer to the bottom of the growth chamber 1 in the adjacent temperature regulating piece 21 layers is larger than that of the temperature regulating piece 21 farther from the bottom of the growth chamber 1, so that the length of each temperature regulating piece 21 is reduced in sequence from the bottom to the top of the growth chamber 1; it can be understood that, after the temperature regulating members 21 are arranged outside the growth chamber 1, the average distance between the growth chamber 1 and the heat source is reduced, the radiant heat exchange energy is improved, the overall temperature of the growth chamber 1 is improved, and the temperature gradient of the accommodating cavity 11 can be directly regulated because the temperature regulating members 21 are gradually reduced in the direction from the bottom to the top of the growth chamber 1. Preferably, in some embodiments, there are a total of four temperature adjustment members 2 arranged in the direction from the bottom to the top of the growth chamber 1, and each temperature adjustment member 2 has a total of eight temperature adjustment members 21, so that the temperature field formed by the growth chamber 1 after absorbing heat has a temperature gradient corresponding to the growth of AlN crystal.
Referring to fig. 1 and fig. 2, in the present embodiment, the temperature adjusting member 21 includes a heat conducting arm 211 fixed on a side of the growth chamber 1 far from the accommodating cavity 11 and a heat receiving unit 212 fixed on an end of the heat conducting arm 211 far from the growth chamber 1, lengths of the heat conducting arms 211 are sequentially reduced along a length extending direction of the accommodating cavity 11, a gap is provided between the heat receiving unit 212 and the heat source, a heat receiving area is provided on a side of the heat receiving unit 212 close to the heat source, and a gap is provided between adjacent heat receiving units 212 on the same layer. Specifically, the heat conducting arm 211 may be a trapezoid, the length extending direction of the heat conducting arm 211 is perpendicular to the length extending direction of the accommodating cavity 11, the heat receiving unit 212 may be a heat receiving sheet, and the heat conducting arm 211 is perpendicularly connected to the heat receiving unit 212; preferably, the heat receiving plate is a rectangle with an arc, which is beneficial to realize the vertical connection between the heat conducting arm 211 and the heat receiving unit 212, and is also beneficial to increase the heat receiving area of the heat receiving unit 212, and improve the heat conduction capability of the temperature adjusting member 21. The lengths of the heat conduction arms 211 are sequentially reduced along the length extension direction of the accommodating cavity 11, so that the temperature adjusting pieces 21 are sequentially reduced along the length extension direction of the accommodating cavity 11, the growth chamber 1 has a temperature gradient with the temperature gradually reduced from the bottom to the top of the growth chamber 1, and the growth of AlN crystals is facilitated; the adjacent heat receiving parts 212 on the same layer are spaced, and the temperature adjusting parts 21 of the temperature adjusting group 2 on the same layer have the same length, which is beneficial to keeping the temperature gradient of the growth chamber 1 stable.
As shown in the figure, in the present embodiment, the connection point of the heat conduction arm 211 and the heat receiving unit 212 is disposed between two ends of the heat receiving unit 212, the cross section of the heat conduction arm 211 has a rectangular structure or a trapezoid-like structure, and one side of the heat receiving unit 212 close to the heat source has an arc surface. Specifically, the heat conduction arm 211 is fixed at the center of the heat receiving unit 212, so that the heat receiving unit 212 can more rapidly conduct heat to the heat conduction arm 211 and conduct the heat to the heat conduction arm 211 through the heat conduction arm 211, thereby improving the preparation efficiency of the AlN crystal. The side of the heated part 212 close to the heat source is a cambered surface, which is beneficial to increasing the heated area of the heated part 212; preferably, the arc curvature of the arc surface is 0cm-1-0.05cm-1E.g. 0.01cm-1And 0.03cm-1And roughness R of the arc surfaceaGreater than 25, e.g. Ra30; as will be appreciated, in the heat transferIn the process, the process is carried out according to the law of conservation of energy, namely Q is Qr + Qa + Qd, wherein r is the reflectivity, a is the absorptivity, and d is the transmissivity, so that the reflectivity and absorptivity of the surface of the object need to be changed when the temperature of the object is increased; obviously, by performing roughness treatment on the side of the heated part 212 close to the heat source, the mirror reflection of the surface to the light is reduced while the heated area is increased, and the heat absorption rate of the heated sheet is improved. In this embodiment, there is also thermal convection heat transfer between the heat source and the growth chamber 1, and the thermal convection heat transfer can reduce the temperature of the growth chamber 1, please refer to fig. 3 and 4, in an embodiment, the heat conduction arm 211 is longitudinally connected to the growth chamber 1, at this time, the cross section of the heat conduction arm 211 along the length extension direction of the accommodation cavity 11 is a rectangular structure, and the side of the heat conduction arm 211 opposite to the heat source can weaken the convection effect in the device body, and increase the temperature of the growth chamber 1. Referring to fig. 1 and 2, in another embodiment, the heat conduction arm 211 is transversely connected to the growth chamber 1, and the cross section of the heat conduction arm 211 along the length extension direction of the accommodating cavity 11 is a trapezoid-like structure, so as to reduce the deformation degree of the heat conduction arm 211.
Referring to fig. 1 and fig. 2, in the present embodiment, the length of the heat conduction arm 211 ranges from 2mm to 35mm, and the thickness ranges from 0.1mm to 2.5 mm; the length of the heated portion 212 ranges from 2mm to 35mm, and the thickness ranges from 0.3mm to 2.5 mm. Preferably, the length of the heat conduction arm 211 ranges from 5mm to 30mm, which can ensure that the heat conduction arm 211 has enough length adjustment, so that the temperature gradient of the temperature field in the growth chamber 1 can be adjusted to be the same as the target temperature gradient of the AlN crystal growth; the thickness range of the heat conduction arm 211 is 0.2mm-2mm, so that the heat conduction arm 211 not only has certain thermal deformation resistance, but also can reduce the loss of heat when the heat conduction arm 211 is transferred; the length of the heated portion 212 ranges from 5mm to 30mm, and the thickness ranges from 0.5mm to 2 mm. It can be understood that, as seen from the heat calculation formula Q ═ cm Δ t (c is the specific heat capacity, m is the mass, Q is the heat, and Δ t is the change temperature of the object), any object consumes heat during the temperature change, and in order to make the temperature adjusting member 21 itself reach a high temperature, the heat loss is small, the mass of the heat conduction arm 211 is controlled by the thickness of the heat conduction arm 211, and the mass of the heat receiving portion 212 is controlled by the thickness of the heat receiving portion 212.
Referring to fig. 5, in the present embodiment, the temperature adjusting member 21 is made of tungsten; the surface of the temperature adjusting part 21 is provided with a coating 3, the absorptivity of the coating 3 is greater than that of tungsten, and the thickness value range of the coating 3 is 500nm-200 um. Specifically, the temperature adjusting part 21 is made of metal tungsten with the purity of more than 99.9%, the coating 3 can be made of graphite and the like, the absorption rate of the coating 3 is greater than that of tungsten, the heat absorption rate of the surface of the temperature adjusting part 21 can be directly changed, the heat absorption capacity of the heated part 212 is improved, the heat loss between a heat source and the temperature adjusting part 21 is further reduced, the temperature of the growth chamber 1 is improved, and the thickness of the coating 3 can be 800nm, 100um and the like; the outer surface of the temperature adjusting piece 21 is coated with high-roughness coating, so that the temperature in the growth chamber 1 can be further increased under the same power, and the electric energy is saved.
As shown in the drawings, in the present embodiment, at least two fixing rings are fixed to the outer side of the growth chamber 1, each fixing ring is distributed along the length extension direction of the accommodating cavity 11, and each temperature adjusting member 21 is fixed to the fixing ring. Specifically, the temperature adjusting piece 21 and the growth chamber 1 can be connected through a fixing ring or can be welded through argon arc welding; when the fixing rings are adopted for connection, the temperature adjusting parts 21 of the temperature adjusting group 2 on the same layer are all fixed on the same fixing ring, and as can be understood, the heat conducting arm 211 is firstly welded on the fixing ring with the same diameter as the outer diameter of the growth chamber 1 during connection, and then the fixing ring is sleeved and fixed on the outer side of the growth chamber 1, so that the connection mode is simplified.
In the present embodiment, in order to verify that the growth chamber 1 can be controlled to provide a temperature gradient suitable for crystal growth by controlling the length of the temperature-adjusting member 21, the following experiment was performed:
test 1:
the growth chamber 1 is provided with four layers of temperature regulating component groups 2 which are distributed in a gradient manner along the length extending direction of the accommodating cavity 11, the same layer of temperature regulating component group 2 is provided with eight temperature regulating components 21, and the lengths of the temperature regulating components 21 of the same layer of temperature regulating component group 2 are equal; wherein the length of the heated part 212 in the temperature adjusting piece 21 is 25mm, the thickness is 0.5mm, the lengths of the heat conducting arms 211 from the bottom of the growth chamber 1 to the top of the growth chamber 1 are respectively 15mm, 12mm, 9mm and 6mm, and the thicknesses are all 0.5 mm; the growth temperature of the crystal is set to be 2150 ℃, the growth atmosphere is 99.999% nitrogen, the growth pressure is 600mbar, and the cooling rate is 200 ℃/h after the crystal growth is finished.
Compared with the growth chamber 1 with a common structure in the prior art, the temperature gradient at the constant temperature stage is 2.2 mm/DEG C, in the experiment, the temperature gradient in the constant temperature process is about 2.5 ℃/mm, and no polycrystal deposits at the bottom of the growth chamber 1.
Test 2: the present test differs from test 1 in that the lengths of the heat-conducting arms 211 from the bottom of the growth chamber 1 to the top of the growth chamber 1 are 9mm, 12mm, 15mm, and 6mm, respectively.
In this test, the temperature gradient during the growth thermostatting process was about 2 ℃/mm, and there was polycrystalline deposition at the bottom of the crucible.
Test 3: the difference between this test and test 1 is the connection mode of the temperature adjusting piece 21, and the growth air pressure is 1500 mbar.
In the test, the temperature gradient in the growth constant temperature process is about 2.5 ℃/mm, and no polycrystal deposition exists at the bottom of the crucible.
As can be known from experiments 1, 2 and 3, the heat transfer principle is applied, the temperature adjusting piece 21 is designed to change an axial temperature field, a constant temperature area in the accommodating cavity 11 can be increased, and the improvement of the effective distance in the accommodating cavity 11 is facilitated.
Example 2:
referring to fig. 6, a method for preparing a crystal, applied to the apparatus for preparing a crystal as described above, includes:
and S100, arranging at least two temperature regulating groups which are distributed in a gradient manner along the length extension direction of the accommodating cavity on the growth chamber according to the corresponding relation between the length of the temperature regulating part and the temperature of the growth chamber.
Specifically, the lengths of the temperature adjusting parts of the same layer of temperature adjusting part group are equal, the lengths of the temperature adjusting parts of the adjacent layer of temperature adjusting part group are unequal, the longer the length of the temperature adjusting part group is, the stronger the heat absorbing capacity of the corresponding position of the growth chamber is, and the higher the temperature of the corresponding position of the growth chamber is; as can be understood, by arranging the temperature adjusting part, the average distance between the heat source and the growth chamber is reduced, the radiation heat exchange energy is improved, and the overall temperature of the growth chamber is improved; simultaneously, the temperature regulating part also has certain compensation effect to growth chamber the latter half low temperature, has improved the space utilization who holds the chamber. In one embodiment, four temperature adjusting parts groups distributed in a positive gradient manner along the length extension direction of the accommodating cavity can be arranged on the growth chamber, eight temperature adjusting parts are arranged on the same temperature adjusting part group, the lengths of the temperature adjusting parts of the same temperature adjusting part group are equal, and the lengths of the temperature adjusting parts from the bottom of the growth chamber to the top of the growth chamber are reduced in sequence.
And S200, placing a crystal source into the accommodating cavity of the growth chamber.
And step S300, after the heat source generates heat and the heat is conducted to the growth chamber through the temperature adjusting piece, the actual temperature gradient of the growth chamber is the same as the target temperature gradient of the crystal, the source material absorbs the heat to sublimate, and the crystal is obtained through deposition at a low temperature.
Specifically, the heat source is the cylinder structure, and the growth room can be cylindric crucible, and the growth room is located the heat source, and the piece that adjusts the temperature is located between heat source and the growth room for the heat that the heat source produced conducts to the growth room through the piece that adjusts the temperature, and the length of the piece that adjusts the temperature can influence the temperature gradient of the growth constant temperature in-process growth room of aluminium nitride crystal, makes the actual temperature gradient of growth room the same with the target temperature gradient of aluminium nitride crystal growth, obtains the aluminium nitride crystal.
The above description is intended to be illustrative of the preferred embodiment of the present invention and should not be taken as limiting the invention, but rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Claims (10)

1. An apparatus for producing a crystal, comprising: the equipment main part, be fixed in the heat source of equipment main part, be fixed in the equipment main part just is located growth chamber in the heat source and be fixed in the growth chamber just is located the heat source with at least two-layer temperature regulating member group between the growth chamber, the growth chamber has the chamber that holds that is used for holding the source material, the one end of the temperature regulating member of temperature regulating member group is fixed in the growth chamber, the other end interval the heat source sets up, and same layer the length of the temperature regulating member of temperature regulating member group equals, and the adjacent layer the length of the temperature regulating member of temperature regulating member group is unequal, the heat conduction that the heat source produced extremely the temperature regulating member and quilt adjust the temperature the piece and conduct extremely the growth chamber.
2. The apparatus of claim 1, wherein the temperature control members are arranged in a gradient along the length of the chamber.
3. The apparatus of claim 2, wherein the growth chamber has a bottom and a top disposed opposite the bottom, a length of a temperature conditioning member of adjacent temperature conditioning member layers closer to the bottom of the growth chamber being greater than a length of a temperature conditioning member further from the bottom of the growth chamber, each layer of the temperature conditioning member group having at least four of the temperature conditioning members disposed at intervals.
4. The apparatus of claim 3, wherein the temperature adjustment member comprises a heat conduction arm fixed to a side of the growth chamber away from the containing cavity, and a heat receiving portion fixed to an end of the heat conduction arm away from the growth chamber, wherein the length of each heat conduction arm decreases in sequence along a length extending direction of the containing cavity, the heat receiving portion is spaced from the heat source, a side of the heat receiving portion close to the heat source has a heat receiving area, and a space is formed between adjacent heat receiving portions on the same layer.
5. The apparatus of claim 4, wherein the connection between the heat conducting arm and the heat receiving unit is located between two ends of the heat receiving unit, the heat conducting arm has a rectangular or trapezoid-like cross section, and the heat receiving unit has an arc surface on a side close to the heat source.
6. The apparatus for producing crystals as claimed in claim 5, wherein the arc curvature of the arc surface is 0cm-1-0.05cm-1And roughness R of the arc surfaceaGreater than 25.
7. The apparatus of claim 4, wherein the thermally conductive arm has a length in the range of 2mm to 35mm and a thickness in the range of 0.1mm to 2.5 mm; the length of the heated part ranges from 2mm to 35mm, and the thickness ranges from 0.3mm to 2.5 mm.
8. The apparatus according to any one of claims 1 to 7, wherein the temperature adjusting member is made of tungsten, a coating is disposed on the surface of the temperature adjusting member, the absorptivity of the coating is greater than that of the tungsten, and the thickness of the coating ranges from 500nm to 200 μm.
9. The apparatus according to claim 1, wherein at least two fixing rings are fixed on the outer side of the growth chamber in a sleeved manner, each fixing ring is distributed along the length extension direction of the containing cavity, and each temperature adjusting member is fixed on the fixing ring.
10. A method for producing a crystal, which is applied to the apparatus for producing a crystal according to any one of claims 1 to 9, comprising:
Arranging at least two layers of temperature regulating element groups on the growth chamber according to the corresponding relation between the length of the temperature regulating element and the temperature of the growth chamber; the lengths of the temperature adjusting parts of the temperature adjusting part groups on the same layer are equal, the lengths of the temperature adjusting parts of the temperature adjusting part groups on the adjacent layers are unequal, and the longer the length of the temperature adjusting part group is, the stronger the heat absorbing capacity of the corresponding position of the growth chamber is;
placing source materials into the accommodating cavity of the growth chamber;
after the heat source generates heat and the heat is conducted to the growth chamber through the temperature adjusting piece, the actual temperature gradient of the growth chamber is the same as the target temperature gradient of crystal growth, and the source material absorbs the heat to sublimate and deposits at a low temperature to obtain the crystal.
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CN104630889A (en) * 2014-12-18 2015-05-20 福建鑫晶精密刚玉科技有限公司 Sapphire single growth furnace heat preservation device capable of conveniently regulating temperature gradient
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