CN113026094A - Silicon carbide single crystal growth control device and control method - Google Patents
Silicon carbide single crystal growth control device and control method Download PDFInfo
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- 239000013078 crystal Substances 0.000 title claims abstract description 115
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims abstract description 112
- 229910010271 silicon carbide Inorganic materials 0.000 title claims abstract description 111
- 238000000034 method Methods 0.000 title claims abstract description 20
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 96
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 95
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 93
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 91
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- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 6
- 229910052721 tungsten Inorganic materials 0.000 claims description 6
- 239000010937 tungsten Substances 0.000 claims description 6
- 230000002829 reductive effect Effects 0.000 claims description 2
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- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical group [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 1
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- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
- C30B23/002—Controlling or regulating
- C30B23/005—Controlling or regulating flux or flow of depositing species or vapour
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/36—Carbides
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Abstract
The invention provides a silicon carbide single crystal growth control device.A reaction chamber is formed in a shell, and a silicon carbide seed crystal placing position is arranged in the reaction chamber; the heating device is arranged in the shell and used for controlling the internal temperature of the reaction chamber; the solid silicon crucible is provided with a first opening to release silicon vapor into the reaction chamber, and the solid carbon crucible is provided with a second opening to introduce carbon vapor into the reaction chamber; the two pressure detectors are respectively positioned above the solid silicon crucible and the solid carbon crucible to respectively monitor the partial pressure of the silicon vapor and the partial pressure of the carbon vapor; the controller adjusts the opening degree of the first opening and the second opening according to the feedback of the two pressure detectors. The invention also provides a silicon carbide single crystal growth control method. The invention adjusts and controls the ratio of the partial pressure of the silicon vapor to the partial pressure of the carbon vapor, so that the ratio of carbon and silicon which is difficult to control in the growth process of the SiC single crystal becomes controllable, thereby improving the quality and the purity of the SiC single crystal.
Description
Technical Field
The invention relates to the technical field of silicon carbide preparation, in particular to a silicon carbide single crystal growth control device and a control method.
Background
Silicon carbide material (SiC) has many advantages: the material has the advantages of wide forbidden band, good heat-conducting property, high breakdown electric field, high electron saturation rate, good thermal stability and strong chemical stability. The SiC has large forbidden band width and is suitable for developing short-wave photoelectronic devices; the heat conducting property is good, and the SiC-based device can work at high temperature; the electron saturation rate is high, and the method is suitable for manufacturing high-frequency devices; the breakdown electric field is high, which is beneficial to manufacturing high-power devices; the chemical stability is strong, and the device can work in a corrosive environment. Therefore, high quality SiC crystals/wafers can be said to be the core foundation of the SiC semiconductor industry, and the links of the SiC semiconductor industry include "SiC single crystal substrate-epitaxial wafer-chip and package-application". Each industrial link has higher requirements on the impurity content of the SiC single crystal wafer. The low quality of the SiC single crystal wafer affects the quality and repeatability of the epitaxial thin film and also causes adverse effects such as excessive leakage current on the device, so high quality of the SiC single crystal is particularly important in the semiconductor industry.
The silicon carbide single crystal can be grown by High Temperature Physical Vapor Transport (HTPVT), specifically, the raw material is in a High Temperature region, the seed crystal is in a relatively low Temperature region, and then the raw material in a higher Temperature region is decomposed, and gas phase Si is directly generated without passing through a liquid phaseXCySubstance (mainly comprising Si, Si)2C、SiC2Etc.), the gas phase substances are transported to the seed crystal under the drive of the axial temperature gradient, nucleation and growth are carried out at the seed crystal, and SiC single crystal is formed by crystallization.
In the prior art, as shown in fig. 1, SiC raw material is used for growing SiC crystal by HTPVT method. At present, the impurity content of the SiC raw material on the market is near to hundred ppm, and such high impurity content is difficult to be used for growing high purity SiC crystals. Silicon carbide powder randomly forms constituent silicon carbide molecules (Si) at high temperaturesXCySubstance), the silicon carbide crystal structure can not be controlled, the carbon silicon atom composition can not be matched, and the generated silicon carbide crystal has many defects and can not be used as the material for manufacturing SiC-based devices.
Disclosure of Invention
The invention mainly aims to provide a silicon carbide single crystal growth control device, which aims to control the ratio of a carbon source and a silicon source so as to grow high-purity and high-quality SiC crystals.
In order to achieve the above object, the present invention provides a silicon carbide single crystal growth control apparatus comprising:
the device comprises a shell, a reaction cavity is formed in the shell, and a silicon carbide seed crystal placing position is arranged in the reaction cavity;
the solid silicon crucible and the solid carbon crucible are arranged in the reaction chamber, and the solid silicon crucible is provided with a first opening so as to release silicon vapor into the reaction chamber; the solid carbon crucible is provided with a second opening to release carbon vapor into the reaction chamber;
the heating device is arranged in the shell and used for controlling the internal temperature of the reaction chamber and heating the solid silicon crucible and the solid carbon crucible;
the first pressure detector and the second pressure detector are arranged in the reaction chamber, and the first pressure detector is positioned above the solid silicon crucible and used for monitoring the partial pressure of silicon vapor; the second pressure detector is positioned above the solid carbon crucible and is used for monitoring the partial pressure of the carbon vapor; and the number of the first and second groups,
the controller is electrically connected with the first pressure detector and the second pressure detector, and when the partial pressure of the silicon vapor fed back by the first pressure detector is higher, the opening degree of the first opening is reduced by the controller; when the second pressure detector feeds back that the partial pressure of the carbon vapor is lower, the controller reduces the opening degree of the second opening.
Optionally, the solid silicon crucible and the solid carbon crucible are both tungsten crucibles.
Optionally, the first opening is provided with a first cover body to adjust the opening degree of the first opening; the second opening is provided with a second cover body so as to adjust the opening degree of the second opening.
Optionally, the first opening and the second opening are both disposed upward, and the silicon carbide seed crystal placement position is disposed at the center of the top wall of the reaction chamber.
Optionally, the heating device is a heating coil, and the heating coil is wound on the peripheral side wall of the reaction chamber.
Optionally, the heating coil includes a plurality of sub-coils arranged side by side from bottom to top, and the heating temperatures of the plurality of sub-coils decrease from bottom to top.
The invention also provides a silicon carbide single crystal growth control method, which comprises the following steps:
placing the silicon carbide seed crystal in a silicon carbide seed crystal placing position in the reaction chamber;
controlling the internal temperature of the reaction chamber by a heating device to heat the solid silicon crucible and the solid carbon crucible, so that the solid silicon crucible releases silicon vapor into the reaction chamber through the first opening, and the solid carbon crucible introduces carbon vapor into the reaction chamber through the second opening; and the number of the first and second groups,
monitoring the partial pressure of the silicon vapor by a first pressure detector and the partial pressure of the carbon vapor by a second pressure detector;
when the partial pressure of the silicon vapor fed back by the first pressure detector is larger, the opening degree of the first opening is adjusted to be smaller by the controller; when the partial pressure of the carbon vapor fed back by the first pressure detector is larger, the opening degree of the second opening is adjusted to be smaller by the controller.
Further, the first opening and the second opening are both arranged upward, the heating device is a heating coil, the heating coil is wound on the peripheral side wall of the reaction chamber, and the step of controlling the internal temperature of the reaction chamber through the heating device specifically comprises the following steps:
and controlling the heating temperature of the heating coil to be decreased from bottom to top.
Further, the step of controlling the internal temperature of the reaction chamber by the heating device may further include the steps of:
controlling the heating temperature range of the solid silicon crucible and the solid carbon crucible to be 2500-2800 ℃;
controlling the temperature range of the silicon carbide seed crystal placement position to be 2000-2300 ℃.
Further, the control method further includes the steps of:
and controlling the vacuum degree range in the reaction chamber to be 0.2-0.7 Pa.
The invention provides a silicon carbide single crystal growth control device, which releases silicon vapor and carbon vapor into a reaction chamber by heating a solid silicon crucible and a solid carbon crucible, respectively monitors the partial pressure of the silicon vapor and the carbon vapor by a pressure detector, and feeds the partial pressure back to a controller to adjust the opening degree of the solid silicon crucible and the solid carbon crucible, so as to adjust and control the ratio of the partial pressure of the silicon vapor to the partial pressure of the carbon vapor to be 1:1, so that the ratio of carbon to silicon which are difficult to control in the growth process of SiC single crystals can be controlled, and the quality and the purity of the generated SiC single crystals can be improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic view showing a prior art silicon carbide crystal production apparatus;
FIG. 2 is a schematic structural view of an apparatus for controlling the growth of a silicon carbide single crystal according to an embodiment of the present invention.
The reference numbers illustrate:
| reference numerals | Name (R) | Reference numerals | Name (R) |
| 100 | |
200 | Silicon carbide seed crystal placing |
| 310 | |
320 | |
| 311 | |
321 | |
| 400 | Heating device | 510 | |
| 520 | Second pressure detector |
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.
In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and/or" appearing throughout is to include three juxtapositions, exemplified by "A and/or B," including either the A or B arrangement, or both A and B satisfied arrangement. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
The embodiment of the invention provides a silicon carbide single crystal growth control device, which aims to prepare a silicon carbide single crystal by adopting a high-temperature physical vapor transport process (HTPVT), and control the ratio of Si in silicon vapor to C in carbon vapor in a reaction chamber by controlling the vapor pressure ratio of solid silicon to solid carbon so as to prepare a high-purity and high-quality SiC crystal.
In an embodiment of the present invention, as shown in fig. 2, the silicon carbide single crystal growth control apparatus includes:
the device comprises a shell 100, wherein a reaction chamber is formed in the shell 100, and a silicon carbide seed crystal placing position 200 is arranged in the reaction chamber;
the solid silicon crucible 310 and the solid carbon crucible 320 are arranged in the reaction chamber, and the solid silicon crucible 310 is provided with a first opening to release silicon vapor into the reaction chamber; the solid carbon crucible 320 is provided with a second opening to release carbon vapor into the reaction chamber;
a heating device 400 disposed in the housing 100 for controlling the internal temperature of the reaction chamber and heating the solid silicon crucible 310 and the solid carbon crucible 320;
a first pressure detector 510 and a second pressure detector 520, both disposed in the reaction chamber, wherein the first pressure detector 510 is located above the solid silicon crucible 310 for monitoring the partial pressure of silicon vapor; the second pressure detector 520 is positioned above the solid carbon crucible 320 to monitor the partial pressure of carbon vapor; and the number of the first and second groups,
the first pressure detector 510 and the second pressure detector 520 are electrically connected with the controller, and when the partial pressure of the silicon vapor fed back by the first pressure detector 510 is higher, the controller reduces the opening degree of the first opening; when the first pressure detector 510 feeds back that the partial pressure of the carbon vapor is low, the controller decreases the opening degree of the second opening.
It is understood that the present embodiment uses High Temperature Physical Vapor Transport (HTPVT) to produce single crystals of silicon carbide by sublimating the material in a high temperature zone, transporting the material to a condensation zone to form a saturated vapor, and performing condensation nucleation to grow crystals. Specifically, solid silicon and solid carbon are respectively placed in two crucibles, the solid silicon and the solid carbon can be directly sublimated under the high-temperature condition and are directly converted into gaseous state from solid state, the sublimated carbon source or silicon source can be emitted in the form of vapor, the silicon vapor is contacted with the carbon vapor and then reacts to form silicon carbide crystals, the silicon carbide crystals nucleate at seed crystals and continuously grow, and finally SiC single crystals are formed. It will be appreciated that the silicon carbide seed placement site 200 is used to place a seed crystal that is used to define the growth region of the SiC single crystal, to promote the formation of the SiC single crystal, and to impart a good crystal orientation thereto.
In this embodiment, the solid silicon is high-purity silicon powder, and the carbon source is high-purity carbon powder. The silicon powder sublimates to generate silicon vapor, and the carbon powder sublimates to generate carbon vapor. The silicon vapor and the carbon vapor are contacted and then react to form the silicon carbide crystal, and the specific chemical equation is as follows:
Si+C＝SiC
it is understood that the ratio of Si to C in the reaction gas should be 1:1, and that if the amount of Si is too large or too small, many defects are formed in the SiC crystal, which affects the quality and purity of the finally produced SiC crystal. Therefore, the quality of the produced SiC crystal can be improved by controlling the ratio of Si to C in the reaction gas.
According to the technical scheme of the embodiment, the solid silicon crucible 310 and the solid carbon crucible 320 are heated to release silicon vapor and carbon vapor in the reaction chamber, the partial pressures of the silicon vapor and the carbon vapor are respectively monitored through the pressure detector, and then the partial pressures are fed back to the controller to adjust the opening degrees of the solid silicon crucible 310 and the solid carbon crucible 320, so that the ratio of the partial pressures of the silicon vapor to the partial pressure of the carbon vapor is adjusted to be 1:1, the ratio of Si to C in the reaction gas is adjusted to be 1:1, and the preparation of the high-purity high-quality SiC single crystal is facilitated.
Further, the solid silicon crucible 310 and the solid carbon crucible 320 are both tungsten crucibles. In the prior art, the crucible material and the heat insulating material for crystal growth are graphite, but the graphite material sold in the market contains a certain amount of impurities, and the impurities in the crystal growth affect the purity and quality of SiC. The melting point of tungsten is 3422 ℃, which is the highest of all metal elements, and is not volatile at high temperature, so that the technical scheme of the embodiment holds solid silicon and solid carbon by adopting the tungsten crucible, which is beneficial to reducing the introduction of impurities and improving the quality and purity of the generated silicon carbide single crystal.
Further, as shown in fig. 2, the first opening is provided with a first cover 311 to adjust the opening degree of the first opening; the second opening is provided with a second cover 321 to adjust the opening degree of the second opening. In this embodiment, it can be understood that, the openings of the two tungsten crucibles are both provided with the covers, and after the covers are opened, the sublimated carbon source or silicon source will emerge in the form of vapor, and the carbon source and the silicon source react to generate SiC crystal after contacting in the reaction chamber. Specifically, when the first pressure detector 510 feeds back that the partial pressure of the silicon vapor is higher, the controller may control the first cover 311 to decrease the opening degree of the first opening, so as to reduce the partial pressure of the silicon vapor; when the partial pressure of the carbon vapor fed back by the second pressure detector 520 is relatively low, the controller controls the second cover 321 to reduce the opening degree of the second opening to reduce the partial pressure of the carbon vapor, and finally adjusts and controls the ratio of the partial pressures of the silicon vapor and the carbon vapor, so that the ratio of carbon to silicon which is difficult to control in the growth process of the SiC single crystal becomes controllable, and the quality and the purity of the generated SiC single crystal are improved.
In this embodiment, the first opening and the second opening are both disposed upward, and the silicon carbide seed crystal placement site 200 is disposed at the top of the reaction chamber. It should be noted that the temperature gradient between the SiC reaction feedstock and the seed crystal is the driving force for SiC crystal growth. Therefore, the first opening and the second opening are both arranged upwards, so that silicon vapor and carbon vapor enter the reaction chamber from bottom to top, and the heating device 400 controls the reaction chamber to form a descending temperature gradient from bottom to top, even if the temperature of the reaction gas initially entering the reaction chamber is higher than that of the growth of the seed crystal, and the generation of the SiC crystal is facilitated.
Further, the silicon carbide seed crystal placement position 200 is disposed at the center of the top wall of the reaction chamber, so that the distances between the solid silicon crucible 310 and the silicon carbide seed crystal and between the solid carbon crucible 320 and the silicon carbide seed crystal are the same, that is, the distances between the silicon vapor and the carbon vapor reaching the silicon carbide seed crystal are the same, thereby facilitating the uniform growth of the silicon carbide single crystal.
In this embodiment, as shown in fig. 2, the heating device 400 is a heating coil, and the heating coil is wound around the peripheral side wall of the reaction chamber. It can be understood that the circumferential sidewall of the reaction chamber is heated by the heating coil to provide high temperature reaction conditions for the reaction gas in the reaction chamber. The heating coil has the characteristics of softness and slender shape, is easy to wind on the peripheral side wall of the reaction chamber, and occupies small space, thereby being beneficial to reducing the whole volume of the silicon carbide single crystal growth control device; in addition, the heating temperature of the heating coil is easy to control, so that the temperature in the reaction chamber is convenient to control.
Further, the heating coil comprises a plurality of sub-coils which are arranged side by side from bottom to top, and the heating temperature of the plurality of sub-coils is decreased progressively from bottom to top. Specifically, the heating temperatures of different sub-coils can be made different by setting the wires of the sub-coils to different thicknesses. From the above analysis, it can be known that the temperature gradient between the SiC reaction raw material and the seed crystal is the driving force for SiC crystal growth, and in this embodiment, the heating coil controls the decreasing temperature gradient formed from bottom to top in the reaction chamber, so that even if the temperature of the reaction gas when initially entering the reaction chamber is higher than the temperature at the growth position of the seed crystal, the SiC crystal is favorably generated. Specifically, the temperature range of silicon vapor and carbon vapor entering the reaction chamber is controlled to be 2500-2800 ℃, and the temperature range of the silicon carbide seed crystal placement position 200 is controlled to be 2000-2300 ℃. In addition, preferably, the temperature gradient is set to be between 5 and 20K/cm, and the higher the temperature gradient is, the higher the supersaturation degree of the gaseous phase substance reaching the surface of the seed crystal is, and the faster the growth rate of the SiC crystal is. However, if the temperature gradient is too high, the crystal growth speed is too high (for example, the speed in the crystal growth direction reaches more than 0.5 mm/h), and the SiC crystal is very easy to generate a heterogeneous crystal form, so that the SiC crystal growth process fails.
The embodiment of the invention also provides a silicon carbide single crystal growth control method, which comprises the following steps:
placing the silicon carbide seed crystal in a silicon carbide seed crystal placing position in the reaction chamber;
controlling the internal temperature of the reaction chamber by a heating device to heat the solid silicon crucible and the solid carbon crucible, so that the solid silicon crucible releases silicon vapor into the reaction chamber through the first opening, and the solid carbon crucible introduces carbon vapor into the reaction chamber through the second opening; and the number of the first and second groups,
monitoring the partial pressure of the silicon vapor by a first pressure detector and the partial pressure of the carbon vapor by a second pressure detector;
when the partial pressure of the silicon vapor fed back by the first pressure detector is larger, the opening degree of the first opening is adjusted to be smaller by the controller; when the partial pressure of the carbon vapor fed back by the first pressure detector is larger, the opening degree of the second opening is adjusted to be smaller by the controller.
It can be understood that, in the technical solution of the present embodiment, the solid silicon crucible and the solid carbon crucible are heated to release silicon vapor and carbon vapor into the reaction chamber, partial pressures of the silicon vapor and the carbon vapor are respectively monitored by the pressure detector, and then fed back to the controller to adjust the opening degrees of the solid silicon crucible and the solid carbon crucible, so as to adjust and control the ratio of the partial pressures of the silicon vapor and the carbon vapor, so that the ratio of carbon and silicon which is difficult to control in the growth process of the SiC single crystal becomes controllable, thereby improving the quality and purity of the generated SiC single crystal.
Further, the first opening and the second opening are both arranged upward, the heating device is a heating coil, the heating coil is wound on the peripheral side wall of the reaction chamber, and the step of controlling the internal temperature of the reaction chamber through the heating device specifically comprises the following steps:
controlling the heating temperature of the heating coil to be decreased from bottom to top;
controlling the temperature range of the silicon vapor and the carbon vapor to be 2500-2800 ℃ when the silicon vapor and the carbon vapor enter the reaction chamber; and the number of the first and second groups,
and controlling the temperature range of the silicon carbide seed crystal placement position to be 2000-2300 ℃.
In the embodiment, the heating coil controls the descending temperature gradient formed in the reaction chamber from bottom to top so as to drive the SiC crystal to grow. It should be noted that, besides the temperature at the seed crystal needs to be controlled to be lower than the temperature when the gas enters the reaction chamber initially, the reaction chamber needs to be controlled to be in a low-pressure state, specifically, the pressure in the reaction chamber is 0.2 to 0.7Pa, and the high temperature and the low pressure are matched to ensure that the reaction gas is in a gaseous state, and the solid matter formed by the chemical reaction starts to deposit through the seed crystal.
Further, the first opening and the second opening are both arranged upward, the heating device is a heating coil, the heating coil is wound on the peripheral side wall of the reaction chamber, and the step of controlling the internal temperature of the reaction chamber through the heating device specifically comprises the following steps:
and controlling the heating temperature of the heating coil to be decreased from bottom to top.
It can be understood that the temperature gradient between the SiC reaction raw material and the seed crystal is the driving force for SiC crystal growth, and in this embodiment, the heating coil controls the decreasing temperature gradient formed in the reaction chamber from bottom to top, even if the temperature of the reaction gas when entering the reaction chamber initially is higher than the temperature at the seed crystal growth, which is beneficial to the generation of SiC crystal.
Further, the step of controlling the internal temperature of the reaction chamber by the heating device may further include the steps of:
controlling the heating temperature range of the solid silicon crucible and the solid carbon crucible to be 2500-2800 ℃;
controlling the temperature range of the silicon carbide seed crystal placement position to be 2000-2300 ℃.
Further, the control method further includes the steps of:
and controlling the vacuum degree range in the reaction chamber to be 0.2-0.7 Pa.
It can be understood that, in this embodiment, in order to complete sublimation of solid silicon and solid carbon, the vacuum degree in the reaction chamber is set to be a low pressure, and the high-temperature and low-pressure condition is favorable for sublimation of silicon powder and carbon powder. Optionally, the vacuum degree in the reaction chamber ranges from 0.2Pa, 0.5Pa and 0.7Pa,
further, the step of controlling the internal temperature of the reaction chamber by the heating means further comprises the steps of:
silicon powder is placed in a solid silicon crucible, and carbon powder is placed in a solid carbon crucible.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. An apparatus for controlling the growth of a silicon carbide single crystal, comprising:
the device comprises a shell, a reaction cavity is formed in the shell, and a silicon carbide seed crystal placing position is arranged in the reaction cavity;
the solid silicon crucible and the solid carbon crucible are arranged in the reaction chamber, and the solid silicon crucible is provided with a first opening so as to release silicon vapor into the reaction chamber; the solid carbon crucible is provided with a second opening to release carbon vapor into the reaction chamber;
the heating device is arranged in the shell and used for controlling the internal temperature of the reaction chamber and heating the solid silicon crucible and the solid carbon crucible;
the first pressure detector and the second pressure detector are arranged in the reaction chamber, and the first pressure detector is positioned above the solid silicon crucible and used for monitoring the partial pressure of silicon vapor; the second pressure detector is positioned above the solid carbon crucible and is used for monitoring the partial pressure of the carbon vapor; and the number of the first and second groups,
the controller is electrically connected with the first pressure detector and the second pressure detector, and when the partial pressure of the silicon vapor fed back by the first pressure detector is higher, the opening degree of the first opening is reduced by the controller; when the second pressure detector feeds back that the partial pressure of the carbon vapor is lower, the controller reduces the opening degree of the second opening.
2. A silicon carbide single crystal growth control apparatus as set forth in claim 1 wherein said solid silicon crucible and said solid carbon crucible are both tungsten crucibles.
3. A silicon carbide single crystal growth control apparatus according to claim 2, wherein the first opening is provided with a first lid body to adjust an opening degree of the first opening; the second opening is provided with a second cover body so as to adjust the opening degree of the second opening.
4. A silicon carbide single crystal growth control apparatus as set forth in claim 1 wherein said first opening and said second opening are both upwardly disposed, and said silicon carbide seed crystal placement site is disposed at the center of the top wall of said reaction chamber.
5. A silicon carbide single crystal growth control apparatus according to claim 4, wherein said heating means is a heating coil disposed so as to be wound around a peripheral side wall of said reaction chamber.
6. A silicon carbide single crystal growth control apparatus as set forth in claim 5, wherein said heating coil comprises a plurality of sub-coils arranged side by side from bottom to top, the heat generation temperature of said plurality of sub-coils being decreased from bottom to top.
7. A silicon carbide single crystal growth control method, characterized by comprising the steps of:
placing the silicon carbide seed crystal in a silicon carbide seed crystal placing position in the reaction chamber;
controlling the internal temperature of the reaction chamber by a heating device to heat the solid silicon crucible and the solid carbon crucible, so that the solid silicon crucible releases silicon vapor into the reaction chamber through the first opening, and the solid carbon crucible introduces carbon vapor into the reaction chamber through the second opening; and the number of the first and second groups,
monitoring the partial pressure of the silicon vapor by a first pressure detector and the partial pressure of the carbon vapor by a second pressure detector;
when the partial pressure of the silicon vapor fed back by the first pressure detector is larger, the opening degree of the first opening is adjusted to be smaller by the controller; when the partial pressure of the carbon vapor fed back by the first pressure detector is larger, the opening degree of the second opening is adjusted to be smaller by the controller.
8. A silicon carbide single crystal growth control method according to claim 7, wherein the first opening and the second opening are both provided facing upward, the heating means is a heating coil which is wound around a peripheral side wall of the reaction chamber, and the step of controlling the internal temperature of the reaction chamber by the heating means specifically comprises the steps of:
and controlling the heating temperature of the heating coil to be decreased from bottom to top.
9. A silicon carbide single crystal growth control method according to claim 8, wherein the step of controlling the internal temperature of the reaction chamber by the heating means further comprises the steps of:
controlling the heating temperature range of the solid silicon crucible and the solid carbon crucible to be 2500-2800 ℃;
controlling the temperature range of the silicon carbide seed crystal placement position to be 2000-2300 ℃.
10. A silicon carbide single crystal growth control method according to claim 8, further comprising the steps of:
and controlling the vacuum degree range in the reaction chamber to be 0.2-0.7 Pa.
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