CN117286568A - Epitaxial growth apparatus and method of silicon carbide substrate, and silicon carbide epitaxial wafer - Google Patents
Epitaxial growth apparatus and method of silicon carbide substrate, and silicon carbide epitaxial wafer Download PDFInfo
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- CN117286568A CN117286568A CN202311563653.6A CN202311563653A CN117286568A CN 117286568 A CN117286568 A CN 117286568A CN 202311563653 A CN202311563653 A CN 202311563653A CN 117286568 A CN117286568 A CN 117286568A
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- 229910010271 silicon carbide Inorganic materials 0.000 title claims abstract description 129
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims abstract description 120
- 239000000758 substrate Substances 0.000 title claims abstract description 83
- 238000000034 method Methods 0.000 title claims abstract description 42
- 238000006243 chemical reaction Methods 0.000 claims abstract description 34
- 239000013077 target material Substances 0.000 claims abstract description 12
- 238000000407 epitaxy Methods 0.000 claims abstract description 7
- 230000003287 optical effect Effects 0.000 claims abstract description 7
- 230000001678 irradiating effect Effects 0.000 claims abstract description 3
- 238000010438 heat treatment Methods 0.000 claims description 11
- NJPPVKZQTLUDBO-UHFFFAOYSA-N novaluron Chemical compound C1=C(Cl)C(OC(F)(F)C(OC(F)(F)F)F)=CC=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F NJPPVKZQTLUDBO-UHFFFAOYSA-N 0.000 claims description 9
- 230000033001 locomotion Effects 0.000 claims description 7
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- -1 silicon carbide ion Chemical class 0.000 description 9
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- 239000012535 impurity Substances 0.000 description 3
- 238000001451 molecular beam epitaxy Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910002601 GaN Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- AJNVQOSZGJRYEI-UHFFFAOYSA-N digallium;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Ga+3].[Ga+3] AJNVQOSZGJRYEI-UHFFFAOYSA-N 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 229910001195 gallium oxide Inorganic materials 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
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- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
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- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
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- 238000001534 heteroepitaxy Methods 0.000 description 1
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
- C30B23/02—Epitaxial-layer growth
- C30B23/06—Heating of the deposition chamber, the substrate or the materials to be evaporated
- C30B23/066—Heating of the material to be evaporated
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/36—Carbides
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- 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 application discloses epitaxial growth equipment and an epitaxial growth method of a silicon carbide substrate and a silicon carbide epitaxial wafer obtained based on the epitaxial growth equipment and/or the epitaxial growth method. The epitaxial growth apparatus may include: a cavity, wherein a reaction space is formed in the cavity; the target base comprises a plurality of first bearing tables for bearing the same or different targets; the substrate base comprises a second bearing table and is used for bearing the silicon carbide substrate; the laser pulse enters the reaction space from the outside through the optical channel; the first bearing tables and the second bearing tables are oppositely arranged in the reaction space; the target mount is configured to move in a controlled manner to move any of the first load tables to a bombarded position; and irradiating the target material on the first bearing table at the bombarded position by the laser pulse to form vapor for epitaxy so as to grow an epitaxial layer on the surface of the silicon carbide substrate on the second bearing table.
Description
Technical Field
The present invention relates to the field of semiconductor device processing, and in particular, to an epitaxial growth apparatus and method for growing a high quality epitaxial layer on a silicon carbide substrate using laser pulses, and a silicon carbide epitaxial wafer obtained based on the apparatus or method.
Background
Silicon carbide epitaxy is a commonly used material growth technique, and various electronic devices and photoelectric devices can be prepared by growing a new monocrystalline layer (i.e., epitaxial layer) on a silicon carbide substrate along the original crystal axis direction. In the existing silicon carbide epitaxial growth method, common techniques include Chemical Vapor Deposition (CVD), molecular Beam Epitaxy (MBE) and the like. However, these methods often have problems in the growth process of epitaxial layers and the like, such as crystal defects, high surface roughness, single epitaxial type, and the like. This limits the performance and application of silicon carbide epitaxial wafers.
In order to improve the quality of silicon carbide epitaxial wafers, there are already some solutions. For example, epitaxial layer growth is performed using optimized CVD and MBE methods to reduce crystal defects and surface roughness. For example, CVD epitaxy is performed a plurality of times to grow a plurality of layers of different doping epitaxy.
Disclosure of Invention
The technical problem to be solved by the method is how to prepare high-quality silicon carbide epitaxial wafers.
In order to solve the problems, the application discloses an epitaxial growth device and an epitaxial growth method of a silicon carbide substrate and a silicon carbide epitaxial wafer obtained based on the epitaxial growth device and/or the epitaxial growth method. The epitaxial growth method adopts laser pulse to realize deposition growth of an epitaxial layer, and can obtain a high-quality silicon carbide epitaxial wafer.
In one aspect, an apparatus for epitaxial growth of a silicon carbide substrate is provided. The epitaxial growth apparatus may include: a cavity, wherein a reaction space is formed in the cavity; the target base comprises a plurality of first bearing tables for bearing the same or different targets; the substrate base comprises a second bearing table and is used for bearing the silicon carbide substrate; the laser pulse enters the reaction space from the outside through the optical channel; the first bearing tables and the second bearing tables are oppositely arranged in the reaction space; the target mount is configured to move in a controlled manner to move any of the first load tables to a bombarded position; and irradiating the target material on the first bearing table at the bombarded position by the laser pulse to form vapor for epitaxy so as to grow an epitaxial layer on the surface of the silicon carbide substrate on the second bearing table.
In some possible embodiments, the target holder comprises a rotary table on which the plurality of first carriages are located, the rotary table being controllably rotationally movable to change the position of the first carriages.
In some possible embodiments, the substrate pedestal is configured for controlled movement, including at least rotation and/or translation.
In some possible embodiments, the horizontal distance between the second carrying stage and the first carrying stage is not more than 10cm.
In some possible embodiments, the laser pulses are generated by a femtosecond laser.
In some possible embodiments, the epitaxial growth apparatus further comprises an air flow channel, and an external air pressure adjusting device is communicated with the reaction space through the air flow channel so as to realize the adjustment of the air pressure in the reaction space.
In some possible embodiments, the substrate pedestal includes a heating assembly for heating the silicon carbide substrate placed on the second susceptor.
In another aspect, the present application provides a method of epitaxial growth of a silicon carbide substrate. The method includes growing at least one epitaxial layer on a silicon carbide substrate using an epitaxial growth apparatus as described above.
In some possible embodiments, the pressure in the reaction space does not exceed 10 during the growth of the epitaxial layer -6 Torr。
Another aspect of the present application provides a silicon carbide epitaxial wafer. The silicon carbide epitaxial wafer can be prepared based on the epitaxial growth equipment or the epitaxial growth method of the silicon carbide substrate.
By implementing the method, the growth of the high-quality silicon carbide epitaxial wafer can be realized, and the silicon carbide epitaxial wafer has the characteristics of high flatness, low roughness and low defect. While the growth of multiple epitaxial layers of different types of silicon carbide, for example, epitaxial layers of different doping types, or epitaxial layers with other crystals, may be achieved.
Drawings
The present application will be further illustrated by way of example embodiments, which will be described in detail with reference to the accompanying drawings. The embodiments are not limiting, in which like numerals represent like structures, wherein:
FIG. 1 is an exemplary block diagram of an epitaxial growth apparatus for silicon carbide substrates according to some embodiments of the present application;
fig. 2 is a schematic cross-sectional structure of an epitaxial growth apparatus according to some embodiments of the present application;
fig. 3 (a) shows the detection result of surface defects of a silicon carbide epitaxial wafer prepared in the prior art;
FIG. 3 (b) is a graph showing the detection of surface defects of a silicon carbide epitaxial wafer according to some embodiments of the present application;
fig. 4 (a) shows the detection result of roughness of a silicon carbide epitaxial wafer prepared in the prior art;
fig. 4 (b) is a measurement of roughness of a silicon carbide epitaxial wafer according to some embodiments of the present application.
Detailed Description
In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is, however, susceptible of embodiment in many other forms than those described herein and similar modifications can be made by those skilled in the art without departing from the spirit of the application, and therefore the application is not to be limited to the specific embodiments disclosed below.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only.
The terms "first," "second," and the like, as used herein, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless explicitly defined otherwise.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" and/or "as used herein includes any and all combinations of one or more of the associated listed items.
There are still some problems with existing methods of epitaxial growth of silicon carbide. Firstly, the CVD method is carried out under the high temperature condition, crystal defects are easy to generate, meanwhile, some impurities are also generated in the growth process, and the uniformity of surface concentration doping is difficult to control. Second, the MBE method requires a high vacuum environment, is complicated in equipment, and has a slow growth rate. In addition, although the method for introducing external energy in the prior art can improve some problems, the problems of low energy utilization efficiency, low growth speed and the like still exist. The growth schemes for multilayer or multilayer heteroepitaxy are costly and not technically mature enough.
According to the technical scheme, the epitaxial layer with higher flatness, low roughness and low defects can be prepared by introducing pulse laser deposition into the epitaxial growth process of the silicon carbide substrate, and the quality and performance of the silicon carbide epitaxial wafer are improved.
Some embodiments of the present application are described below with reference to the accompanying drawings. It should be noted that the following description is for illustrative purposes and is not intended to limit the scope of the present application.
Referring to fig. 1 and 2, fig. 1 is an exemplary structural diagram of an epitaxial growth apparatus of a silicon carbide substrate according to some embodiments of the present application, and fig. 2 is an exemplary cross-sectional schematic diagram of the epitaxial growth apparatus according to some embodiments of the present application. As shown in fig. 1 and 2, the epitaxial growth apparatus 100 may include a chamber 110, a target mount 120, a substrate mount 130, and an optical channel 140.
The chamber 110 may be used to form a reaction space in which the silicon carbide substrate is epitaxially grown. For example, the interior of the chamber 110 is hollow, and this hollow region may be the reaction space. In some possible implementations, the shape of the cavity 110 may be regular or irregular. For example, the cavity 110 may have a regular shape such as a sphere, an ellipse, a cube, or an irregular shape formed by combining two or more regular shapes. The material of the material can be stainless steel, or outer-layer iron-inner-layer stainless steel, or outer-layer stainless steel-inner-layer silicon carbide, or the like, or other materials. The interior of the chamber 110 may also be provided with a thermal insulation layer, such as a carbon felt, graphite felt, carbon fiber solidified felt, etc., for maintaining the temperature inside the reaction space.
The target holder 120 may be used to carry a target. For example, the target base 120 may include a plurality of first stages 121, and one target may be placed on each of the first stages 121. Targets placed on different first carriers 121 may be the same or different. For example, the target base 120 may include two first bearing tables 121, where one of the first bearing tables is provided with a silicon carbide target, and the other one of the first bearing tables may be provided with a silicon carbide target, and may be provided with other targets such as gallium nitride, gallium oxide, P-type ion doped silicon carbide, N-type ion doped silicon carbide, and the like. It is known that the target acts to generate ion vapors (also known as plasma radicals) for epitaxial growth under bombardment by laser pulses. Thus, the target base 120 may be configured to controllably move to move any of the plurality of first carriers 121 to the bombarded position. In this bombarded position, the target placed on the first stage 121 may receive the irradiation of the laser pulse. As shown in fig. 2, the target base 120 may include a rotation stage 122. The plurality of first bearing tables 121 may be disposed on the rotation table 122. The rotary table 122 may be fixedly connected to the first moving shaft 123, for example, welded, bonded, riveted, or the rotary table 122 is integrally formed with the first moving shaft 123. The first moving shaft 123 is rotated by external power such as a motor, thereby rotating the first bearing table 121. The motor may be controlled to output power to enable the first stage 121 to reach a defined position, such as the bombarded position described above, to receive laser pulse radiation. Therefore, if the same target is placed on the plurality of first bearing tables 121, continuous epitaxial growth of the silicon carbide substrate can be realized, and the production efficiency is improved. If different targets are placed on the first bearing tables 121, different epitaxial layers can be grown on the same silicon carbide substrate, so that different production requirements can be met.
The substrate pedestal 130 may include a second susceptor 131, and the second susceptor 131 may be used to carry a silicon carbide substrate that is desired to be epitaxially grown. It will be appreciated that it is necessary to ensure that the epitaxial layer is grown uniformly and that the thickness of each portion is uniform when the epitaxial growth is performed. Thus, the substrate pedestal 130 may also be configured to move in a controlled manner so as to uniformly contact the silicon carbide substrate with the ion vapor. As shown in fig. 2, the substrate pedestal 130 may include a second axis of motion 132. The second moving shaft 132 is fixedly connected with the second bearing table 131, for example, welded or integrally formed with the second bearing table 131, and can be driven by external power such as a motor to rotate, so as to drive the second bearing table 131 to rotate. In addition, the laser flux of the laser pulses impinging on the target may be varied, and thus the rate, size, and motion of the ion beam formed may be varied. To accommodate different application scenarios, the substrate pedestal 130 may also be translated to change the horizontal distance between the silicon carbide substrate on the second stage 131 and the target on the first stage 121 for better receiving ion vapors for epitaxial growth. In some achievable embodiments, the horizontal distance between the first bearing stage 121 and the second bearing stage 131 may not exceed 10cm. For example, the distance may be 5cm, 6cm, 7cm, 8cm, 9cm, 10cm, etc.
In order to achieve the bonding of the ion vapour to the silicon carbide substrate to grow an epitaxial layer on its growth surface, the growth surface of the silicon carbide substrate needs to be active. A heating assembly (not shown) disposed above the substrate pedestal 130 may be used to heat the silicon carbide substrate placed on the second susceptor 131 to activate its surface for bonding with the ion vapor.
The optical channel 140 may provide access for laser pulses to the reaction space inside the cavity 110. Laser pulses emitted by a laser generator located outside the epitaxial growth apparatus 100 may enter the reaction space through the optical channel 140 and impinge on the target material on the first susceptor 121 located at the bombarded position, thereby generating ion vapors. The generated ion vapor may be deposited on a growth surface of the silicon carbide substrate located on the second susceptor 131 to form an epitaxial layer. In some implementations, the laser generator for generating the laser pulses may be a femtosecond laser. The femtosecond laser can generate laser pulse with higher energy, so that the ionization degree of the generated ion steam is larger, and the subsequent epitaxial growth is more facilitated.
The epitaxial growth apparatus 100 may also include an air flow channel (not shown in the drawings). The air pressure adjusting means located outside the epitaxial growth apparatus 100 may be communicated with the reaction space through an air flow passage for adjusting the air pressure inside the reaction space. In some embodiments, the reaction space may be evacuated by the air pressure regulating device (e.g., an air pump, etc.) through an air flow channel to achieve a high vacuum environment of the reaction space. The high vacuum environment will facilitate the formation of ion vapors from the etched away material from the target after bombardment by the laser pulses.
In some implementations, the above target mount 120 (including the motor coupled thereto), the substrate mount 130 (including the motor coupled thereto), the laser generator, and the air pressure adjustment device may be electrically coupled to the control device. The control device can control the movement and operation of the various components. For example, the control device may control the heating assembly of the substrate holder 130 to heat the silicon carbide substrate placed on the second susceptor 131 to a heating temperature. For another example, the control device may control the rotation of the target base 120 so that the first bearing table 121 reaches the position to be bombarded. Also for example, the control means may control the power of the laser generator and the pulse frequency to emit laser pulses. For another example, the control device may rotate and translate the substrate pedestal 130 to receive ion vapors to grow an epitaxial layer on the growth surface of the silicon carbide substrate. For another example, the control device may control the air pressure adjusting device to adjust the pressure of the reaction space to the target pressure. The above control may be performed synchronously or sequentially.
The application also discloses a method for growing the silicon carbide epitaxial wafer by using the epitaxial growth equipment 100. The method is illustrated in the following by way of specific examples. It should be noted that this example is for illustrative purposes only and is not intended to limit the present application.
A silicon carbide substrate (e.g., a 4H or 6H silicon carbide substrate) may be used as a base material placed on the second susceptor 131. Different targets (e.g., different silicon carbide targets) may be placed on the plurality of first carrier tables 121, respectively. The reaction space may then be depressurized, for example by evacuating the reaction space using a gas pressure regulator, to a pressure of 10 -6 Not more than 10 Torr -6 Torr。
The laser generator is then activated to generate a high energy laser pulse. For example, a 248nm wavelength Kr-F femtosecond laser is used to generate high energy laser pulses. The pulse frequency may be, for example, between 4 and 10Hz. Such as 4Hz, 5Hz, 6Hz, 7Hz, 8Hz, 9Hz, 10Hz, etc. The laser fluence may be at 150W/cm2. The generated laser pulses enter the reaction space through the optical channel 140 and impinge on the silicon carbide target on the first stage 121 in the bombarded position. After the high-energy laser pulse bombards the silicon carbide target, the silicon carbide substances on the surface of the silicon carbide target can be stripped, and silicon carbide ion vapor is formed in the high-vacuum cavity.
The silicon carbide ion vapor will form feathered clusters moving toward the silicon carbide substrate due to coulomb forces and recoil. After the silicon carbide substrate is subjected to heating treatment (for example, to 1400-1550 ℃) by the heating component of the substrate base 130, the surface of the silicon carbide substrate has activity, and can be recombined with silicon carbide ion steam to gradually grow a silicon carbide epitaxial layer.
The second susceptor 131 carrying the silicon carbide substrate may be 5-10 cm from the first susceptor 121 carrying the target, and the silicon carbide substrate for epitaxial growth may be pretreated. For example, the growth surface may be polished, such as by mechanical polishing, CMP, etc., and particle cleaning, as required for epitaxial growth. After the silicon carbide ion steam contacts the growth surface of the silicon carbide substrate, the silicon carbide ion steam is condensed and nucleated on the growth surface, reaches thermal equilibrium and is deposited on the growth surface.
In order to achieve uniform growth of the epitaxial layer, the second susceptor 131 may be rotated synchronously while the silicon carbide substrate is contacted with silicon carbide ion vapor. The epitaxial layer growth process may be a stepwise growth. For example, when the silicon carbide substrate is a 2 ° -8 ° cut silicon carbide substrate, atoms fall on the surface and diffuse to the step edges, each step can act as a nucleation and diffusion boundary, and the deposition rate can also be increased.
During the whole epitaxial layer growth process, the epitaxial layer growth can be regulated by controlling laser parameters (including laser flux, power, pulse time and the like), the heating temperature of the silicon carbide substrate, the quality control of the growth surface, the pressure of the reaction space and the like. For example, increasing the laser fluence may increase the ionization degree of the ion vapor, thereby increasing the nucleation density at the growth surface of the silicon carbide substrate, thereby increasing the deposition rate. As another example, an increase in the temperature of the silicon carbide substrate will result in a decrease in nucleation density. While lower temperatures can increase condensation and nucleation densities, thereby increasing deposition rates. As another example, high quality (e.g., high flatness, no or few defects, etc.) of the growth surface of the silicon carbide substrate may improve deposition rates and crystal quality of the epitaxial layer. Also for example, the pressure within the reaction space will affect the mass shape and rate of movement of the ion vapour, while low pressure will facilitate high rate deposition on the growth surface. Therefore, the growth thickness control of the epitaxial layer of the silicon carbide substrate can be realized by adjusting the parameters, and the high-quality growth of the epitaxial layer can be realized at the same time.
As one example, the following parameter settings are used: the silicon carbide substrate is heated to 1400 ℃, the laser wavelength is 248nm of KrF, the pulse frequency is 10HZ, the laser energy is 200W/cm < 2 >, the rotation speed of the second bearing table is 10rpm, and the growth of the buffer layer with the growth speed of 10-15 micrometers/H and the growth thickness of 1 mu m can be realized. The concentration of the ion vapor obtained by the laser bombardment of the target is 1E18/cm < 3 >, and the growth time is 400 seconds. The target was then switched and growth of a second layer (i.e., an epitaxial layer) was performed, wherein the concentration of the ion vapor was 6E15, the growth thickness of the epitaxial layer was 10 microns, and the growth time was 3000 seconds.
As another example, the following parameter settings are used: the silicon carbide substrate is heated to 1450 ℃, the laser wavelength is 248nm of KrF, the pulse frequency is 5HZ, the laser energy is 185W/cm < 2 >, the rotation speed of the second bearing table is 10rpm, and the growth of the buffer layer with the growth speed of 10-15 micrometers/H and the growth thickness of 1.5 mu m can be realized. Wherein the concentration of the ion vapor obtained by the laser bombardment of the target material is 1E18/cm < 3 >, and the growth time is 450 seconds. The target was then switched and a second layer (i.e., an epitaxial layer) was grown with ion vapor concentration 8.5E15 and epitaxial layer growth thickness 5 microns for 1800 seconds.
In addition, since the plurality of first loading tables 121 included on the target base 120 can place different targets. Thus, different epitaxial layers can be grown on silicon carbide substrates by laser pulse bombardment of different targets. Alternatively, the growth of stacked multiple different epitaxial layers may be achieved sequentially on a silicon carbide substrate.
According to the epitaxial growth equipment and the epitaxial growth method of the silicon carbide substrate, high-energy laser pulses are adopted to bombard a target material (including a silicon carbide target material or other target materials) in a high-vacuum reaction space, and substances on the surface of the target material can be eroded, stripped and ionized through the high energy of the laser pulses to form a plasma air mass. The diffusion motion of the plasma clusters may form feathered plasma clusters. The shape and the diffusion size of the plasma cluster can be adjusted by controlling the pressure inside the reaction space. And simultaneously, placing a silicon carbide substrate which needs epitaxial layer growth at a proper position away from the target material, and heating the silicon carbide substrate. After the plasma clusters are contacted with the silicon carbide substrate after temperature rise and collide, the thermal balance is achieved. The species used to grow the epitaxial layer (e.g., silicon carbide ion vapor, silicon dioxide ion vapor, gallium oxide ion vapor, gallium nitride ion vapor, etc., X) will nucleate and grow on the growth surface of the silicon carbide substrate. In the whole growth process of the epitaxial wafer, the ionization degree of the target material and the deposition efficiency/time of the plasma air mass on the silicon carbide substrate can be controlled through parameter control, so that the thickness of the epitaxial layer is controlled. Through the technical scheme of this application, can produce high-quality carborundum epitaxial wafer, including the demand of multilayer carborundum epitaxial layer.
The epitaxial wafer is grown by using the laser pulse, and compared with the traditional physical vapor deposition or chemical vapor deposition, the epitaxial wafer has high growth speed and better growth uniformity. The epitaxial growth based on laser pulse can also be carried out at a lower temperature, avoiding impurity doping and crystal defect formation at high temperature. Meanwhile, the epitaxial wafer growth process can be carried out in a high vacuum environment (such as a high vacuum reaction space in a cavity in the application), so that the pollution and the oxidation influence of impurities can be effectively reduced, and the purity and the crystal quality of the grown silicon carbide epitaxial wafer are ensured. And the high vacuum environment can provide better reaction conditions, so that the growth process of the epitaxial wafer is more stable and controllable. In addition, based on the epitaxial growth equipment disclosed by the application, the target can be freely switched in the epitaxial layer growth process, and the epitaxial wafer with special requirements can be grown simply and rapidly. The method has great cost and technical advantages for the high-quality deposited epitaxial wafer of ultra-multilayer, mixed doping type and epitaxy of a plurality of different materials.
The application also discloses a silicon carbide epitaxial wafer. The silicon carbide epitaxial wafer can be based on the epitaxial growth method equipment or the epitaxial growth method of the silicon carbide substrate, has the characteristics of high flatness, low roughness, low defects and the like, and improves the quality and performance. Referring to fig. 3 (a) to 4 (b), fig. 3 (a) shows the result of detecting the surface defect of the silicon carbide epitaxial wafer prepared by the prior art, fig. 3 (b) shows the result of detecting the surface defect of the silicon carbide epitaxial wafer shown in some embodiments according to the present application, fig. 4 (a) shows the result of detecting the roughness of the silicon carbide epitaxial wafer prepared by the prior art, and fig. 4 (b) shows the result of detecting the roughness of the silicon carbide epitaxial wafer shown in some embodiments according to the present application. In fig. 3, (a) shows the surface defect condition of a silicon carbide epitaxial wafer prepared by a CVD method, and (b) shows the surface defect condition of a silicon carbide epitaxial wafer prepared by the technical scheme of the present application. Wherein the dots in the figures represent defects. The comparison between the two silicon carbide epitaxial wafers can be obviously known, and compared with the prior art, the silicon carbide epitaxial wafer prepared by the technical scheme has the advantage that the defects are greatly reduced. Fig. 4 (a) shows the roughness of a silicon carbide epitaxial wafer prepared by a CVD method, and (b) shows the roughness of a silicon carbide epitaxial wafer prepared by the technical scheme of the present application. Wherein the scale below the figure indicates the picture size, e.g. 20.0 μm x 20 μm. The color bands of different gray scale composition on the right side of the figure and the numerical values represent the height of the test area compared to the base plane (or can be considered to be higher or lower than the base plane). Compared with the prior art, the silicon carbide epitaxial wafer prepared by the technical scheme has better flatness and smoother surface. The silicon carbide epitaxial wafer disclosed by the application is obtained after deposition of the plasma air mass obtained after bombardment of the target material in a high vacuum environment by laser pulse on the growth surface of the silicon carbide substrate, and has higher growth speed and better uniformity of an epitaxial layer. Meanwhile, the epitaxial layer grows in a high vacuum environment, so that the purity and the crystal quality of the silicon carbide epitaxial wafer can be ensured. At the same time, parameter control during growth enables thickness adjustment of the epitaxial layers (e.g., between hundreds of nanometers and several hours of microns) and enables growth of multiple epitaxial layers (including differently doped epitaxial layers). The silicon carbide epitaxial wafer disclosed by the application has the characteristics of high flatness, low roughness and low defect.
Having described the basic concepts herein, it will be apparent to those skilled in the art that the foregoing detailed disclosure is by way of example only and is not intended to be limiting. Although not explicitly described herein, various modifications, improvements, and adaptations to the present disclosure may occur to one skilled in the art. Such modifications, improvements, and modifications are intended to be suggested within this specification, and therefore, such modifications, improvements, and modifications are intended to be included within the spirit and scope of the exemplary embodiments of the present invention.
It should be noted that in order to simplify the presentation disclosed in this specification and thereby aid in understanding one or more embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of the preceding description of the embodiments of the present specification. This method of disclosure, however, is not intended to imply that more features than are presented in the claims are required for the present description. Indeed, less than all of the features of a single embodiment disclosed above.
Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments of this specification. Other variations are possible within the scope of this description. Thus, by way of example, and not limitation, alternative configurations of embodiments of the present specification may be considered as consistent with the teachings of the present specification. Accordingly, the embodiments of the present specification are not limited to only the embodiments explicitly described and depicted in the present specification.
Claims (10)
1. An epitaxial growth apparatus of a silicon carbide substrate, characterized in that the epitaxial growth apparatus comprises:
a cavity, wherein a reaction space is formed in the cavity;
the target base comprises a plurality of first bearing tables for bearing the same or different targets;
the substrate base comprises a second bearing table and is used for bearing the silicon carbide substrate;
the laser pulse enters the reaction space from the outside through the optical channel; wherein,
the first bearing tables and the second bearing tables are oppositely arranged in the reaction space;
the target mount is configured to move in a controlled manner to move any of the first load tables to a bombarded position; and irradiating the target material on the first bearing table at the bombarded position by the laser pulse to form vapor for epitaxy so as to grow an epitaxial layer on the surface of the silicon carbide substrate on the second bearing table.
2. The epitaxial growth apparatus of claim 1, wherein the target mount comprises a turntable on which the plurality of first susceptors are located, the turntable being controllably rotated to change the position of the first susceptors.
3. The epitaxial growth apparatus of claim 1, wherein the substrate base is configured for controlled movement, including at least rotation and/or translation.
4. The epitaxial growth apparatus of claim 1, wherein a horizontal distance between the second susceptor and the first susceptor is no more than 10cm.
5. The epitaxial growth apparatus of claim 1, wherein the laser pulses are generated by a femtosecond laser.
6. The epitaxial growth apparatus of claim 1, further comprising an air flow channel through which an external air pressure regulating device communicates with the reaction space to effect regulation of air pressure within the reaction space.
7. The epitaxial growth apparatus of claim 1, wherein the substrate pedestal comprises a heating assembly for heating the silicon carbide substrate placed on the second susceptor.
8. A method of epitaxial growth of a silicon carbide substrate, the method comprising:
growing at least one epitaxial layer on the silicon carbide substrate using the epitaxial growth apparatus of any of claims 1-7.
9. The epitaxial growth method according to claim 8, wherein the pressure in the reaction space does not exceed 10 during the growth of the epitaxial layer -6 Torr。
10. A silicon carbide epitaxial wafer, characterized in that the silicon carbide epitaxial wafer is produced using the epitaxial growth apparatus of a silicon carbide substrate according to any one of claims 1 to 7 or the epitaxial growth method of a silicon carbide substrate according to claim 8 or 9.
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