CN111254486A

CN111254486A - Crystal preparation device

Info

Publication number: CN111254486A
Application number: CN202010373329.8A
Authority: CN
Inventors: 王宇; 杨田; 梁振兴
Original assignee: Meishan Boya New Materials Co Ltd
Current assignee: Meishan Boya New Materials Co Ltd
Priority date: 2020-05-06
Filing date: 2020-05-06
Publication date: 2020-06-09
Also published as: CN113106541B; CN113089084A; CN113089084B; CN113089083B; CN113089083A; CN113089085A; CN113089085B; CN113106541A

Abstract

The application provides a crystal preparation device. The crystal preparation apparatus includes: a growth chamber for placing seed crystals and source material; the heating assembly is used for heating the growth cavity; the temperature compensation assembly is used for providing temperature compensation in the crystal growth process, wherein the temperature compensation assembly is positioned on the upper surface or the lower surface of the growth cavity body, and the temperature compensation assembly comprises at least one heating unit.

Description

Crystal preparation device

Technical Field

The application relates to the technical field of semiconductor equipment, in particular to a crystal preparation device.

Background

Semiconductor crystals (e.g., silicon carbide single crystals) have excellent physicochemical properties and are therefore important materials for the manufacture of high frequency and high power devices. Physical Vapor Transport (PVT) is a commonly used method for preparing semiconductor crystals, specifically, a seed crystal is bonded to the top of a growth chamber, a material is placed at the bottom of the growth chamber, and a heating element (e.g., an induction coil) is wound outside the growth chamber to heat the growth chamber. The material is decomposed and sublimated into gas-phase components under the high-temperature condition, the gas-phase components are transmitted to the seed crystal in the low-temperature region under the drive of the axial temperature gradient, and crystals are generated on the surface of the seed crystal through deposition. However, during the growth of the crystal, there is not only an axial temperature gradient, but also a radial temperature gradient. When large-size crystals grow, the larger radial temperature gradient can cause crystal growth defects, and the quality and yield of the crystals are reduced; in addition, the radial temperature gradient of the material coverage area is large, so that the mol ratio of each sublimed gas-phase component is not uniformly distributed along the radial direction, and the stable growth of crystals is not facilitated. Therefore, there is a need for an improved crystal production apparatus for producing large-size, high-quality crystals.

Disclosure of Invention

One aspect of the present application provides a crystal preparation apparatus. The device comprises: a growth chamber for placing seed crystals and source material; the heating assembly is used for heating the growth cavity; and the temperature compensation assembly is used for providing temperature compensation in the crystal growth process, wherein the temperature compensation assembly is positioned on the upper surface and/or the lower surface of the growth cavity body, and comprises at least one heating unit.

In some embodiments, the at least one heating unit comprises at least one high resistance graphite unit.

In some embodiments, the temperature compensation assembly further comprises a fixing frame comprising at least one fixing unit for placing the at least one heating unit.

In some embodiments, the fixed frame is a zirconia ceramic plate.

In some embodiments, the temperature compensation assembly further comprises at least one first electrode, at least one second electrode, and an electrode fixing plate, wherein: the electrode fixing plate comprises at least one first hole and at least one second hole; the at least one first electrode penetrates through the at least one first hole and is fixed on the at least one heating unit; and the at least one second electrode penetrates through the at least one second hole and is fixed on the upper surface or the lower surface of the growth cavity.

In some embodiments, the electrode fixing plate further comprises at least two temperature measuring holes, and the at least two temperature measuring holes are located between the radially adjacent first holes or within a preset range of the at least one second hole.

In some embodiments, the crystal growth apparatus further comprises a control assembly for adjusting a parameter of the at least one heating unit based on at least one reference parameter such that a radial temperature gradient of an upper or lower surface of the growth chamber is less than a preset threshold.

In some embodiments, the at least one reference parameter comprises crystal type, seed size, or temperature information associated with the growth chamber during crystal growth.

In some embodiments, the temperature information associated with the growth chamber comprises a first temperature at the at least one heating unit and a second temperature at a periphery of an upper or lower surface of the growth chamber.

In some embodiments, the control assembly comprises at least one temperature measuring unit for measuring the first temperature and the second temperature.

In some embodiments, the at least one temperature measurement unit measures the first temperature and the second temperature through at least two temperature measurement holes on the temperature compensation assembly.

Drawings

The present application will be further explained by way of exemplary embodiments, which will be described in detail by way of the accompanying drawings. These embodiments are not intended to be limiting, and in these embodiments like numerals are used to indicate like structures, wherein:

FIG. 1 is a schematic view of an exemplary crystal production apparatus according to some embodiments of the present application;

FIG. 2A is a top view of an exemplary heating unit arrangement according to some embodiments of the present application;

FIG. 2B is a top view of an exemplary heating unit arrangement according to some embodiments of the present application;

FIG. 3 is a schematic illustration of an exemplary first electrode and an exemplary second electrode shown in accordance with some embodiments of the present application;

fig. 4 is a top view of an exemplary electrode mounting plate according to some embodiments of the present application.

In the figure: 100 is a crystal preparation device; 110 is a growth chamber; 120 is a heating component; 130 is a temperature compensation component; 111 is a growth chamber cover; 112 is a growth chamber body; 113 is seed crystal; 114 is a source material; 131 is a fixed frame; 132 is a heating unit; numeral 133 denotes a first electrode; 134 is a second electrode; 135 is copper wire; 136 is an electrode fixing plate; 136-1 is a first hole; 136-2 is a second hole; 136-3 is a temperature measuring hole.

Detailed Description

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the description of the embodiments will be briefly introduced below. It is obvious that the drawings in the following description are only examples or embodiments of the application, from which the application can also be applied to other similar scenarios without inventive effort for a person skilled in the art. Unless otherwise apparent from the context, or otherwise indicated, like reference numbers in the figures refer to the same structure or operation. It is to be understood that the drawings are for purposes of illustration and description only and are not intended as a definition of the limits of the application. It should be understood that the drawings are not to scale.

It should be understood that for the convenience of description of the present application, the terms "center", "upper surface", "lower surface", "upper", "lower", "top", "bottom", "inner", "outer", "axial", "radial", "peripheral", "outer", etc. indicate positional relationships based on those shown in the drawings, and do not indicate that the device, component, or unit being referred to must have a particular positional relationship, and should not be construed as limiting the present application.

As used in this application and the appended claims, the terms "a," "an," "the," and/or "the" are not intended to be inclusive in the singular, but rather are intended to be inclusive in the plural unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" merely indicate that steps and elements are included which are explicitly identified, that the steps and elements do not form an exclusive list, and that a method or apparatus may include other steps or elements.

In the present application, the terms "crystal preparation" and "crystal growth" are used synonymously and are used interchangeably.

FIG. 1 is a schematic view of an exemplary crystal production apparatus according to some embodiments of the present application. In some embodiments, the crystal preparation apparatus 100 can prepare semiconductor crystals (e.g., silicon carbide crystals, aluminum nitride crystals, zinc oxide crystals, zinc antimonide crystals) based on a physical vapor transport method. As shown in fig. 1, crystal preparation apparatus 100 may include a growth chamber 110, a heating assembly 120, and a temperature compensation assembly 130.

Growth chamber 110 may be used to place seed 113 and source material 114. In some embodiments, growth chamber 110 may include a growth chamber cover 111 and a growth chamber body 112, wherein the growth chamber cover 111 is located on top of the growth chamber body for closing the top end opening of the growth chamber body 112. By way of example only, the growth chamber 110 may be a crucible, which may include a crucible lid and a crucible body. In some embodiments, the growth chamber body 112 may be cylindrical, cuboid, cubic, or the like in shape. For example, growth chamber body 112 may be in the shape of a cylindrical bucket body that includes a bucket bottom and bucket sidewalls. In some embodiments, growth chamber cover 111 may be shaped as a circular disk, a rectangular disk, a square disk, or the like, corresponding to the shape of growth chamber body 112. In some embodiments, the material of the growth chamber 110 may include graphite. For example, the growth chamber 110 may be made of graphite, in whole or in part.

In some embodiments, the seed crystal 113 may be fixedly attached to an inner side (also referred to as a "lower surface") of the growth chamber cover 111 (e.g., at a center of the inner side), and the source material 114 may be disposed within the growth chamber body 112 (e.g., at a lower portion of the chamber). In some embodiments, the seed crystal 113 may be secured to the growth chamber cover 111 by an adhesive. The adhesive may include, but is not limited to, epoxy glue, AB glue, phenolic glue, sugar glue, and the like. In some casesIn embodiments, the source material may be in powder, granular, block, or the like. During crystal growth, an axial temperature gradient may be formed between the source material 114 and the seed crystal 113 by controlling the heating environment of the growth chamber. The source material 114 may decompose and sublimate into a vapor phase component upon heating (e.g., vapor phase component including Si, as exemplified by the production of silicon carbide crystals)₂C、SiC₂Si), the gas phase component is transported from the surface of the source material 114 to the surface of the seed crystal 113 under the driving action of the axial temperature gradient, and the gas phase component is crystallized on the surface of the seed crystal 113 to generate crystals due to the relatively low temperature at the seed crystal 113.

The heating assembly 120 may be used to heat the growth chamber 110. In some embodiments, the heating assembly 120 may include an electrical heating device, an electromagnetic induction heating device, or the like. For example, the heating assembly 120 may be an induction coil. In some embodiments, the heating assembly 120 is located outside of the growth chamber 110 for providing at least some of the heat required for crystal growth. Taking the inductive coil as an example, the inductive coil can generate eddy current on the surface of the growth cavity 110 under the action of the medium-frequency alternating current, and under the action of the eddy current, the electric energy generated on the surface of the growth cavity 110 is converted into heat energy to heat the surface layer of the growth cavity 110 and conduct heat to the inside of the growth cavity 110. In combination with the above, under the action of the temperature field within the growth chamber 110, the source material 114 sublimes and decomposes into gas phase components, which are transported to the surface of the seed crystal 113 for crystallization under the driving action of the axial temperature gradient to produce a crystal.

In some embodiments, the temperature field within the growth chamber 110 may be varied by adjusting (e.g., adjusting up and down along the outer surface of the growth chamber 110) the position of the heating assembly 120 and/or the heating parameters (e.g., current parameters) applied to the heating assembly 120 to produce a suitable temperature gradient profile to promote crystal growth. Taking the induction coil as an example, the induction coil may be spirally wound outside the growth chamber 110, and the distance between adjacent coils is gradually increased from the lower portion to the upper portion of the growth chamber 110 to control the temperature field in the growth chamber 110, thereby generating a suitable temperature gradient distribution. For another example, the induction coil may include a plurality of connected sub-induction coils, and the heating parameters of each sub-induction coil may be separately controlled to control the temperature field within the growth chamber 110 to produce a suitable temperature gradient profile. The number and/or the position of the sub induction coils can be set by default of the system, and can be adjusted according to different conditions.

Temperature compensation assembly 130 may be used to provide temperature compensation during crystal growth. In some embodiments, the temperature compensation component 130 may be located on the upper and/or lower surface of the growth chamber 110. For example, the temperature compensation assembly 130 may be located near the center of the upper surface and/or near the center of the lower surface of the growth chamber 110. In conventional crystal preparation devices, an induction coil is typically placed outside the growth chamber for heating the growth chamber. Thus, heat is conducted from the peripheral region of the growth chamber to the central region of the growth chamber, resulting in a high temperature region in the peripheral region and a relatively low temperature region in the central region, with lower temperatures closer to the central region. As mentioned above, for the upper region of the growth cavity (for example, the inner side of the growth cavity cover where the seed crystal is placed), such radial temperature gradient may cause the growth surface of the seed crystal to generate a large thermal stress, even the growth surface of the seed crystal protrudes seriously towards the direction of the source material, and defects such as micropipes and inclusions are easily generated; for lower regions of the growth chamber (e.g., source material blanket regions), such radial temperature gradients can result in non-uniform radial distribution of the molar ratio of the sublimated gas phase component of the source material, affecting crystal quality. Therefore, there is a need to reduce this radial temperature gradient. Accordingly, the temperature compensation assembly 130 may provide temperature compensation to reduce the radial temperature gradient. When the temperature compensation assembly 130 is located on the upper surface of the growth chamber 110, the radial temperature gradient of the inner side surface (or called as "lower surface") of the growth chamber cover 111 can be reduced, so that defects caused by stress of the crystal growth surface can be reduced, and corrosion defects of the back surface of the crystal can be reduced or avoided; when the temperature compensation assembly 130 is located on the lower surface of the growth chamber 110, the radial temperature gradient of the source material coverage area can be reduced, and the uniformity of radial temperature distribution can be improved, so that the molar ratio of the sublimated gas phase component is more uniform in radial distribution, and the quality of the generated crystal can be improved. As an example, only the case where the temperature compensation assembly 130 is located on the upper surface of the growth chamber 110 is shown in fig. 1.

In some embodiments, the temperature compensation assembly 130 may include at least one heating unit 132. In some embodiments, the at least one heating unit 132 may comprise at least one high resistance graphite unit. In some embodiments, the at least one heating unit 132 may be uniformly or non-uniformly distributed in the radial direction on the upper surface or the lower surface of the growth chamber 110. In some embodiments, parameters of the at least one heating unit 132 ((e.g., number, shape, size, arrangement, current, heating power of the at least one heating unit 132)) may be adjusted according to the size of the upper or lower surface of the growth chamber 110, the type of crystal to be grown, the shape or size of the seed crystal 113, the temperature distribution of the upper or lower surface of the growth chamber 110, etc., in some embodiments, the parameters (e.g., heating power, current) of each of the at least one heating unit 132 may be individually controlled to adjust the radial temperature gradient distribution.

In some embodiments, the temperature compensation assembly 130 may further include a fixing frame 131, and the fixing frame 131 may include at least one fixing unit for placing at least one heating unit 132. In some embodiments, the fixed frame 131 may be coaxial with the growth cavity 110. In some embodiments, the fixing frame 131 may be made of a heat insulating material or a heat insulating material. For example, the fixed frame 131 may be a zirconia ceramic plate or a boron nitride ceramic plate. In some embodiments, at least one of the securing units may be removably connected. In some embodiments, the shape of the at least one fixing unit may include a regular pattern or an irregular pattern such as a hexagon, a square, a circle, a triangle, and the like. Accordingly, the shape of the at least one heating unit 132 may also include regular patterns or irregular patterns such as a hexagon, a square, a circle, a triangle, etc. Further description of the at least one securing unit and the at least one heating unit 132 may be found elsewhere in the present application (e.g., fig. 2A, 2B, and description).

In some embodiments, the temperature compensation assembly 130 may further include at least one first electrode 133, at least one second electrode 134, and an electrode holding plate 136, wherein the electrode holding plate 136 is used to hold the first electrode 133 and the second electrode 134. In some embodiments, the materials of the first electrode 133 and the second electrode 134 may be the same or different. For example, the first electrode 133 and the second electrode 134 may both be low-resistance graphite electrodes. In some embodiments, the shape of the first electrode 133 and the second electrode may be the same or different. For example, the first electrode 133 and the second electrode 134 may both be cylindrical electrodes, and the diameter of the first electrode 133 is smaller than the diameter of the second electrode 134. In some embodiments, the first electrode 133 and the second electrode 134 may be connected to a power source (e.g., a direct current power source) through a wire (e.g., a copper wire 135). In some embodiments, the electrode fixing plate 136 may be made of a heat insulating material or a heat insulating material. For example, the electrode fixing plate 136 may be a zirconia ceramic plate. In some embodiments, the electrode fixing plate 136 may include at least one first hole 136-1 and at least one second hole 136-2 (as shown in fig. 4), the at least one first electrode 133 is fixed to the at least one heating unit 132 through the at least one first hole 136-1, and the at least one second electrode 134 is fixed to the upper surface or the lower surface of the growth chamber 110 through the at least one second hole 136-2. Accordingly, the first electrode 133, the at least one heating unit 132, the upper surface or the lower surface of the growth chamber 110, and the power supply form a current path for heating the at least one heating unit 132. In some embodiments, the electrode fixing plate 136 may further include at least two temperature measuring holes 136-3 located between the radially adjacent first holes 136-1 or within a predetermined range of at least one second hole 136-2. In some embodiments, the temperature at the at least one heating unit 132 or the temperature at the periphery of the upper or lower surface of the growth chamber 110 may be measured through at least two temperature measuring holes 136-3. Further description of the at least two temperature sensing apertures 136-3 may be found elsewhere in this application (e.g., FIG. 4 and its description).

In some embodiments, crystal preparation apparatus 100 may further include a control assembly (not shown) for adjusting parameters of at least one heating unit 132 (e.g., number, shape, size, arrangement, current, heating power of at least one heating unit 132) based on at least one reference parameter such that a radial temperature gradient of an upper surface or a lower surface of growth chamber 110 is less than a preset threshold (e.g., 10K). In some embodiments, the preset threshold may be a default value of the system, or may be adjusted according to different situations. For example, when different crystals are prepared, the preset threshold may be different accordingly. In some embodiments, the at least one reference parameter may include a crystal type, a seed size or shape, temperature information associated with the growth chamber body 110 during crystal growth, and the like. Taking silicon carbide crystals as an example, the silicon carbide crystals have three crystal types of a close-packed hexagonal structure, a cubic structure and a rhombohedral structure. The silicon carbide crystal can include 3C-SiC, 4H-SiC, 6H-SiC, 15R-SiC, and the like, wherein 3C-SiC is a cubic structure, 4H-SiC is a hexagonal close packed structure, 6H-SiC is a hexagonal close packed structure, and 15R-SiC is a rhombohedral structure. The radial temperature gradient profile of the inner side region of growth chamber cover 111 can be tailored to the growth of a different silicon carbide crystal type by adjusting the parameters of at least one heating unit 132 for that type of silicon carbide crystal. As another example, the size or shape of the seed crystal may be varied accordingly for different crystal growth needs. Accordingly, for different sizes or shapes of seed crystals, the radial temperature gradient distribution of the inner side area of the growth chamber cover 111 can be adapted to the size or shape of seed crystal to grow into high-quality crystal by adjusting the parameters of the at least one heating unit 132.

In some embodiments, the temperature information associated with the growth chamber body 110 during crystal growth may include a first temperature at the at least one heating unit 132 and a second temperature at the periphery of the upper or lower surface of the growth chamber body 110. Taking the temperature compensation assembly 130 as an example of being located on the upper surface of the growth chamber 110, the at least one heating unit 132 may be radially arranged on the outer side surface of the growth chamber cover 111 (i.e., the upper surface of the growth chamber 110) with reference to the center of the growth chamber cover 111. Accordingly, the first temperature may include at least one temperature (may also be referred to as "at least one first temperature") distributed radially on the upper surface of the growth chamber 110. The control assembly may compare the difference between the at least one first temperature and the second temperature and adjust a parameter of the at least one heating unit 132 such that the radial temperature gradient across the growth chamber cover 111 is less than a preset threshold.

In some embodiments, the control assembly may include at least one temperature measurement unit (not shown) for measuring the first temperature and the second temperature. In some embodiments, the at least one temperature measurement unit may comprise a thermometer (e.g., an infrared thermometer). In some embodiments, at least one temperature measurement unit may measure the first temperature and the second temperature through at least two temperature measurement holes 136-3 on the temperature compensation assembly 130. As described above, at least two temperature measuring holes 136-3 are located between the radially adjacent first holes, and at least one first hole corresponds to at least one heating unit 132, so that the temperature measuring unit can measure a first temperature at the at least one heating unit 132 through the temperature measuring holes; similarly, the at least two temperature measuring holes are also located within a predetermined range (e.g., 2 cm) of the at least one second aperture, so that the temperature measuring unit can measure the second temperature at the periphery of the upper surface of the growth cavity through the temperature measuring holes.

It should be noted that the above description of crystal preparation apparatus 100 is intended for purposes of illustration and description only and is not intended to limit the scope of applicability of the present application. Various modifications and alterations to crystal preparation apparatus 100 will be apparent to those skilled in the art in light of the present disclosure. However, such modifications and variations are intended to be within the scope of the present application.

FIG. 2A is a top view of an exemplary heating unit arrangement according to some embodiments of the present application; fig. 2B is a top view of an exemplary heating unit arrangement according to some embodiments of the present application.

As previously described, the fixing frame 131 includes at least one fixing unit for placing at least one heating unit 132. As shown in fig. 2A, the fixing frame 131 may be formed by connecting 7 hollowed-out regular hexagonal fixing units, and accordingly, the shape of the heating unit 132 is also regular hexagonal. As shown in fig. 2B, the fixing frame 131 may be formed by connecting 9 hollow square fixing units, and accordingly, the shape of the heating unit 132 is also square. In some embodiments, the number of the fixing units 132 arranged thereon may be increased or decreased according to the area of the upper surface or the lower surface of the growth chamber 110.

FIG. 3 is a schematic illustration of an exemplary first electrode and an exemplary second electrode shown in accordance with some embodiments of the present application; fig. 4 is a top view of an exemplary electrode mounting plate according to some embodiments of the present application.

As shown in fig. 3 and 4, at least one first electrode 133 is fixed to at least one heating unit 132 through at least one first hole 136-1, and at least one second electrode 134 is fixed to the upper surface or the lower surface of the growth chamber 110 through at least one second hole 136-2. In some embodiments, the shapes of the first electrode 133 and the second electrode 134 may be the same or different. For example, the first electrode 133 and the second electrode 134 may both be cylindrical electrodes, and the diameter of the first electrode 133 is smaller than the diameter of the second electrode 134. In some embodiments, the first electrode 133 and the second electrode 134 may be connected to a power source (e.g., a direct current power source) through a wire (e.g., a copper wire 135). When the copper wire 135 is connected to a power source, the first electrode 133, the at least one heating unit 132, the upper surface or the lower surface of the growth chamber 110, and the power source form a current path for heating the at least one heating unit 132.

As described above, the electrode fixing plate 136 may further include at least two temperature measuring holes 136-3, and the at least one temperature measuring unit may measure the first temperature at the at least one heating unit 132 and the second temperature at the outer circumference of the upper surface or the lower surface of the growth chamber 110 through the at least two temperature measuring holes 136-3. As shown in FIG. 4, at least two temperature measuring holes 136-3 may be located between radially adjacent first holes 136-1 or within a predetermined range of at least one second hole 136-3. The shape of the temperature measuring hole 136-3 can be a regular pattern or an irregular pattern such as a circle, a square, a polygon and the like. In some embodiments, at least one temperature measuring unit may measure a first temperature at the at least one heating unit 132 and a second temperature at the periphery of the upper surface or the lower surface of the growth chamber 110 through the at least two temperature measuring holes 136-3, thereby obtaining a temperature distribution of the upper surface or the lower surface of the growth chamber 110. Further, the control assembly may adjust parameters of the at least one heating unit 132 (e.g., number, shape, size, arrangement, current, heating power of the at least one heating unit 132) based at least on the first temperature and the second temperature such that a radial temperature gradient of the upper surface or the lower surface of the growth chamber 110 is less than a preset threshold.

For example, assuming that the number of the heating units 132 is 7 and the arrangement is as shown in fig. 2A, correspondingly, 7 first electrodes 133 are fixed at the heating units 132 through 7 first holes 136-1, further, 4 second electrodes 134 are placed at the periphery of the upper surface or the lower surface of the growth chamber 110 and 4 second electrodes 134 are fixed at the upper surface or the lower surface of the growth chamber 110 through 4 second holes 136-2. The 6 first temperatures T1, T2, T3, T4, T5 and T6 at the heating unit 132 are sequentially detected through the temperature measuring hole 136-3 by the infrared thermometer in a clockwise direction. In addition, 4 second temperatures P1, P2, P3, and P4 at the outer circumference of the upper surface or the lower surface of the growth chamber 110 are sequentially detected through the temperature measuring hole 136-3 by the infrared thermometer at the same time. If at least one of the 4 second temperatures is less than or greater than the preset temperature P, and/or if at least one of the 6 first temperatures is less than or greater than the preset temperature T, the parameters of the heating unit 132 are adjusted until the 4 second temperatures are equal to the preset temperature P and/or the 6 first temperatures are equal to the preset temperature T, wherein the preset temperature T is less than the preset temperature P, and the temperature difference between the preset temperature T and the preset temperature P is less than a preset threshold (e.g., 10K). As another example, an average temperature of the 4 second temperatures may be calculated

Then the average temperature is measured

Respectively comparing with 6 first temperatures, if at least one of the 6 first temperatures is greater than the average temperature

Or if at least one of the 6 first temperatures is less than the average temperature

And the temperature difference is greater than the preset threshold, based on the average temperature

Adjusting parameters of the heating unit 132 until the 6 first temperatures are less than the average temperature

And the temperature difference is less than a preset threshold (e.g., 10K).

The embodiment of the application also discloses a crystal preparation method, which prepares a semiconductor crystal through the crystal preparation device 100. For convenience, the following will be described taking the preparation of a silicon carbide single crystal as an example. The method may comprise the steps of:

step 1: the seed crystal is bonded to the inner side of the growth chamber cover 111, and the source material is placed into the growth chamber body 112, and the growth chamber cover 111 bonded with the seed crystal is fitted on the top of the growth chamber body 112.

Firstly, the adhesive can be uniformly coated on the inner side surface of the growth cavity cover 111, then the growth cavity cover 111 coated with the adhesive is placed in a heating furnace, heat preservation is carried out for 5 hours at the temperature of 150-180 ℃, heat preservation is carried out for 7-10 hours at the temperature of 200 ℃, and the growth cavity cover is taken out after being cooled to the room temperature. Then, a seed crystal was placed at the very center of the inner side surface of the growth chamber cover 111, a silicon carbide single crystal piece was placed on the seed crystal, and a stainless steel piece was placed on the silicon carbide single crystal piece. And then placing the mixture into a heating furnace, preserving the heat for 5 hours at the temperature of 380-430 ℃, and taking out the mixture after cooling to room temperature.

The direction of the growth surface of the seed crystal is a [11 ] direction deflected by 4-6 degrees from 0001 ]. The adhesive may include, but is not limited to, epoxy glue, AB glue, phenolic glue, sugar glue, or the like. Preferably, the binder may be sucrose having a purity of 99.9%. The stainless steel block is used for applying certain pressure to the silicon carbide single crystal wafer, the seed crystal and the growth cavity cover 111 to promote the seed crystal to be bonded to the inner side surface of the growth cavity cover 111. In the process of adhering and fixing the seed crystal, due to the reasons of uneven coating of the adhesive, poor processing precision of the inner side surface of the growth cavity cover and the like, bubbles or gaps are possibly generated between the back surface of the seed crystal and the inner side surface of the growth cavity cover 111, and further the generated crystal contains defects, so that the generation of the bubbles or the gaps is avoided when the seed crystal is placed in the center of the inner side surface of the growth cavity cover 111. In some embodiments, the seed crystal may also be cleaned to remove contaminants from the surface of the seed crystal prior to bonding the seed crystal to the inside surface of the growth chamber cover. For example, the seed crystal may be washed with deionized water, an organic solvent, or the like.

Next, a source material (e.g., silicon carbide powder) may be placed into the growth chamber body 112 such that the distance between the source material upper surface and the seed crystal growth face is 30-50 mm. The particle size of the source material may be 30 to 50 μm. The surface of the source material placed into growth chamber body 112 needs to remain flat.

After the source material is placed in the growth chamber main body 112, the growth chamber cover 111 bonded with the seed crystal is covered on the top of the growth chamber main body 112 to form a closed space, so as to be beneficial to the growth of the crystal.

Step 2: a heating element 120 is placed outside the growth chamber body 110.

As shown in fig. 1, the heating element 120 may be an induction coil located at the periphery of the growth chamber 110 for providing at least part of the heat required for crystal growth. When the induction coil is energized with current, the growth chamber 110 is heated, and the source material (e.g., silicon carbide powder) is thermally decomposed and sublimated to a gas phase component (e.g., Si) under high temperature conditions₂C、SiC₂Si), the gas phase component is transported to the surface of the seed crystal at a relatively low temperature under the driving action of the axial temperature gradient, and the crystal (e.g., silicon carbide crystal) is crystallized. In some embodiments, control of the axial temperature gradient may be achieved by controlling the heating power of the induction coil at different positions in the axial direction.

As described in other positions of the present application, if the growth chamber 110 is heated only by the induction coil disposed at the periphery of the growth chamber 110, the region near the inner wall of the growth chamber 110 is a high temperature region, and the region near the center of the source material is a low temperature region, at this time, the radial temperature gradient of the source material coverage region is large, which is not beneficial to the sublimation of the source material and the stable growth of the crystal. For example, since the radial temperature gradient of the source material coverage area is large, the mole ratio of Si/C in the gas phase component generated by sublimation of the source material is large in the high temperature region near the inner wall of the growth chamber 110, and the mole ratio of Si/C in the gas phase component generated by sublimation of the source material is small in the low temperature region near the center of the source material, so that the radial distribution of the mole ratio of Si/C in the gas phase component is not uniform, which is not favorable for stable growth of the crystal. In addition, for the growth chamber cover 111, the area near the periphery of the growth chamber cover 111 is a high temperature area, and the area near the center of the growth chamber cover 111 is a low temperature area, at this time, a large radial temperature gradient exists on the growth chamber cover 111, which causes a large thermal stress to be generated on the growth surface of the seed crystal, the growth surface of the seed crystal protrudes seriously towards the source material direction, and a defect is formed on the fixing surface of the seed crystal. The radial temperature gradient of the growth chamber cover 111 and the radial temperature gradient of the source material coverage area can thus be reduced by providing the temperature compensation device 130 on the upper and/or lower surface of the growth chamber body 110.

And step 3: the temperature compensation device 130 is mounted to the upper surface and/or the lower surface of the growth chamber 110.

In some embodiments, a fixing frame 131 including at least one fixing unit may be fixed to an upper surface or a lower surface of the growth chamber 110, and at least one heating unit 132 is infill-fixed into the at least one fixing unit. The electrode fixing plate 136 is then covered and the at least one first electrode 133 is fixed to the at least one heating unit 132 through the at least one first hole 136-1 of the electrode fixing plate 136, while the at least one second electrode 134 is fixed to the upper surface and/or the lower surface of the growth chamber 110 through the at least one second hole 136-2 of the electrode fixing plate 136. Further, the upper ends of the at least one first electrode 133 and the at least one second electrode 134 are connected to copper wires 135, respectively, and the copper wires 135 are connected to a power source.

As described elsewhere herein, the number, size, shape, arrangement, etc. of the at least one heating unit 132 may be determined based on the size of the upper or lower surface of the growth chamber 110, the type of crystal to be grown, the size or shape of the seed crystal, the temperature (axial and/or radial temperature gradient) distribution within the growth chamber 110, etc. For example, the thickness of the heating unit 132 may be 5 to 10mm, and the side length may be 10 to 30 mm.

And 4, step 4: at least one temperature measuring unit is connected to the heating unit 132 and the outer circumference of the upper or lower surface of the growth chamber 110 through at least two temperature measuring holes 136-3. At least two temperature measuring holes 136-3 are positioned between the first holes 136-1 which are adjacent in the radial direction or at least one second hole 136-3 within a preset range.

In some embodiments, at least one temperature measuring unit may measure a first temperature at the at least one heating unit 132 and a second temperature at the outer circumference of the upper or lower surface of the growth chamber 110 through at least two temperature measuring holes 136-3 of the electrode fixing plate 136, thereby obtaining a temperature distribution of the upper or lower surface of the growth chamber 110.

And 5: introducing an inert gas (e.g., argon) into the growth chamber 110, controlling the pressure to be 5-30 Torr, and heating the growth chamber 110 by the heating assembly 120 and the temperature compensation device 130.

Step 6: the first temperature at the heating unit 132 and the second temperature at the periphery of the upper surface or the lower surface of the growth chamber 110 are measured by at least one temperature measuring unit, and parameters of at least one heating unit 132 (e.g., the number, shape, size, arrangement, current, heating power of at least one heating unit 132) are adjusted based on at least the first temperature and the second temperature, so that the radial temperature gradient of the upper surface or the lower surface of the growth chamber 110 is less than a preset threshold value, and uniform crystal growth is promoted. Further description regarding adjusting parameters of the at least one heating unit 132 based on the first temperature and the second temperature may be found elsewhere in this application (e.g., fig. 3, 4, and descriptions thereof).

In some embodiments, the temperature of the growth chamber 110 is maintained within a range of 2200 to 2400 ℃ during sublimation of the source material during the crystal growth process, and the duration of the sublimation process of the source material may be 40 to 60 hours. In some embodiments, the temperature of the growth chamber cover 111 is maintained within a range of 2100-2350 ℃ during the crystal growth process, and the first temperature of the heating unit 132 at the upper surface of the growth chamber 110 is lower than the second temperature at the periphery of the growth chamber cover 111, and the temperature difference is maintained within 10K.

The above preparation processes are only examples, and the process parameters involved in the preparation processes may be different in different embodiments, and the sequence of the above steps is not unique, and the sequence between the steps may be adjusted in different embodiments, even if one or more steps are omitted. The above examples should not be construed as limiting the scope of the present application.

The beneficial effects that may be brought by the embodiments of the present application include, but are not limited to: (1) the temperature compensation assembly is arranged on the upper surface of the growth cavity, so that the radial temperature gradient of the inner side surface of the growth cavity cover caused by heating of the induction coil can be reduced, the defect caused by the stress of the crystal growth surface is reduced, the corrosion defect of the back surface of the crystal is reduced or avoided, and the quality and the yield of the crystal are improved; (2) the temperature compensation assembly is arranged on the lower surface of the growth cavity, so that the radial temperature gradient of a source material coverage area caused by heating of the induction coil can be reduced, the uniformity of radial temperature distribution is improved, the radial distribution uniformity of the mole ratio of sublimation gas-phase components is improved, and the stable growth of crystals is promoted; (3) according to the size of the upper surface or the lower surface of the growth cavity, the type of the crystal to be grown, the size or the shape of the seed crystal, the temperature distribution in the growth cavity and the like, the parameters of the heating units in the temperature compensation assembly can be flexibly adjusted, and the parameters of each heating unit can be independently controlled; (4) the temperature distribution of the upper surface or the lower surface of the growth cavity in the crystal growth process is monitored, and the parameters of the temperature compensation assembly are adjusted to ensure the stable and high-quality growth of the crystal. It is to be noted that different embodiments may produce different advantages, and in different embodiments, any one or combination of the above advantages may be produced, or any other advantages may be obtained.

Having thus described the basic concept, it will be apparent to those skilled in the art that the foregoing detailed disclosure is to be considered merely illustrative and not restrictive of the broad application. Various modifications, improvements and adaptations to the present application may occur to those skilled in the art, although not explicitly described herein. Such modifications, improvements and adaptations are proposed in the present application and thus fall within the spirit and scope of the exemplary embodiments of the present application.

Also, this application uses specific language to describe embodiments of the application. Reference throughout this specification to "one embodiment," "an embodiment," and/or "some embodiments" means that a particular feature, structure, or characteristic described in connection with at least one embodiment of the present application is included in at least one embodiment of the present application. Therefore, it is emphasized and should be appreciated that two or more references to "an embodiment" or "one embodiment" or "an alternative embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, some features, structures, or characteristics of one or more embodiments of the present application may be combined as appropriate.

Similarly, it should be noted that in the preceding description of embodiments of the application, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the embodiments. This method of disclosure, however, is not intended to require more features than are expressly recited in the claims. Indeed, the embodiments may be characterized as having less than all of the features of a single embodiment disclosed above.

Numerals describing the number of components, attributes, etc. are used in some embodiments, it being understood that such numerals used in the description of the embodiments are modified in some instances by the use of the modifier "about", "approximately" or "substantially". Unless otherwise indicated, "about", "approximately" or "substantially" indicates that the number allows a variation of ± 20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximations that may vary depending upon the desired properties of the individual embodiments. In some embodiments, the numerical parameter should take into account the specified significant digits and employ a general digit preserving approach. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the range are approximations, in the specific examples, such numerical values are set forth as precisely as possible within the scope of the application.

The entire contents of each patent, patent application publication, and other material cited in this application, such as articles, books, specifications, publications, documents, and the like, are hereby incorporated by reference into this application. Except where the application is filed in a manner inconsistent or contrary to the present disclosure, and except where the claim is filed in its broadest scope (whether present or later appended to the application) as well. It is noted that the descriptions, definitions and/or use of terms in this application shall control if they are inconsistent or contrary to the statements and/or uses of the present application in the material attached to this application.

Finally, it should be understood that the embodiments described herein are merely illustrative of the principles of the embodiments of the present application. Other variations are also possible within the scope of the present application. Thus, by way of example, and not limitation, alternative configurations of the embodiments of the present application can be viewed as being consistent with the teachings of the present application. Accordingly, the embodiments of the present application are not limited to only those embodiments explicitly described and depicted herein.

Claims

1. A crystal manufacturing apparatus, comprising:

a growth chamber for placing seed crystals and source material;

the heating assembly is used for heating the growth cavity; and

a temperature compensation assembly for providing temperature compensation during crystal growth, wherein,

the temperature compensation component is positioned on the upper surface and/or the lower surface of the growth cavity, an

The temperature compensation assembly includes at least one heating unit.

2. The crystal preparation apparatus of claim 1, wherein the at least one heating unit comprises at least one high resistance graphite unit.

3. The crystal preparation apparatus of claim 1, wherein the temperature compensation assembly further comprises a fixed frame comprising at least one fixed unit for placement of the at least one heating unit.

4. The crystal preparation apparatus of claim 3, wherein the fixed frame is a zirconia ceramic plate.

5. The crystal preparation apparatus of claim 1, wherein the temperature compensation assembly further comprises at least one first electrode, at least one second electrode, and an electrode holding plate, wherein:

the electrode fixing plate comprises at least one first hole and at least one second hole;

the at least one first electrode penetrates through the at least one first hole and is fixed on the at least one heating unit; and

and the at least one second electrode penetrates through the at least one second hole and is fixed on the upper surface or the lower surface of the growth cavity.

6. The crystal preparation apparatus of claim 5, wherein the electrode fixing plate further comprises at least two temperature measuring holes, and the at least two temperature measuring holes are located between the first holes which are radially adjacent or within a preset range of the at least one second hole.

7. The crystal preparation apparatus of claim 1, further comprising a control assembly configured to adjust a parameter of the at least one heating unit based on at least one reference parameter such that a radial temperature gradient of an upper or lower surface of the growth chamber is less than a preset threshold.

8. The crystal preparation apparatus of claim 7, wherein the at least one reference parameter comprises a crystal type, a seed size, or temperature information associated with the growth chamber during crystal growth.

9. The crystal preparation apparatus of claim 8, wherein the temperature information related to the growth chamber comprises a first temperature at the at least one heating unit and a second temperature at a periphery of an upper or lower surface of the growth chamber.

10. The crystal preparation apparatus of claim 9, wherein the control assembly comprises:

at least one temperature measuring unit for measuring the first temperature and the second temperature.

11. The crystal preparation apparatus of claim 10, wherein the at least one temperature measurement unit measures the first temperature and the second temperature through at least two temperature measurement holes on the temperature compensation assembly.