CN115595663A - Treatment method of silicon carbide seed crystal and growth method of silicon carbide crystal - Google Patents
Treatment method of silicon carbide seed crystal and growth method of silicon carbide crystal Download PDFInfo
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- CN115595663A CN115595663A CN202211523460.3A CN202211523460A CN115595663A CN 115595663 A CN115595663 A CN 115595663A CN 202211523460 A CN202211523460 A CN 202211523460A CN 115595663 A CN115595663 A CN 115595663A
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims abstract description 193
- 229910010271 silicon carbide Inorganic materials 0.000 title claims abstract description 193
- 239000013078 crystal Substances 0.000 title claims abstract description 96
- 238000000034 method Methods 0.000 title claims abstract description 35
- 239000003513 alkali Substances 0.000 claims abstract description 79
- 239000002585 base Substances 0.000 claims abstract description 68
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 51
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 51
- 230000007797 corrosion Effects 0.000 claims abstract description 50
- 238000005260 corrosion Methods 0.000 claims abstract description 50
- 239000007787 solid Substances 0.000 claims description 61
- 238000005530 etching Methods 0.000 claims description 26
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 22
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 15
- 229910052759 nickel Inorganic materials 0.000 claims description 11
- 238000001035 drying Methods 0.000 claims description 8
- 239000008367 deionised water Substances 0.000 claims description 7
- 229910021641 deionized water Inorganic materials 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 238000007664 blowing Methods 0.000 claims description 6
- 238000012545 processing Methods 0.000 claims description 5
- 230000008569 process Effects 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 238000000861 blow drying Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 4
- 239000004065 semiconductor Substances 0.000 abstract description 4
- 238000003672 processing method Methods 0.000 abstract description 3
- 230000009471 action Effects 0.000 abstract description 2
- 238000004321 preservation Methods 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000004927 fusion Effects 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000000635 electron micrograph Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005240 physical vapour deposition Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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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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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
- C30B33/08—Etching
- C30B33/10—Etching in solutions or melts
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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
- C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
- C30B33/08—Etching
- C30B33/12—Etching in gas atmosphere or plasma
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention relates to the field of semiconductor materials, in particular to a processing method of silicon carbide seed crystals and a growth method of silicon carbide crystals. The method comprises the steps of sequentially carrying out alkali steam corrosion and molten alkali corrosion on a silicon carbide wafer, converting dislocation of a base plane of a carbon surface of the silicon carbide wafer into corrosion pits, simultaneously obtaining silicon carbide seed crystals with relatively flat surfaces, and carrying out silicon carbide crystal growth by utilizing the finally obtained silicon carbide seed crystals. The method aims at the problem that the silicon carbide wafer obtained after alkali steam corrosion is continuously subjected to molten alkali corrosion, the corrosion speed of the molten alkali corrosion on the carbon surface of the silicon carbide wafer is low, the silicon carbide seed crystal with a flat surface is finally formed by controlling the time of the molten alkali corrosion, the silicon carbide seed crystal is used for growing the silicon carbide crystal, exposed corrosion pits are forced to be combined under the action of enhanced mirror image force when the crystal grows, and the basal plane dislocation is converted into the through type edge dislocation, so that the crystal with low basal plane dislocation density is obtained.
Description
Technical Field
The invention relates to the field of semiconductor materials, in particular to a processing method of silicon carbide seed crystals and a growth method of silicon carbide crystals.
Background
Silicon carbide is a representative material of third-generation semiconductors, and has the advantages of rapid development and wide application. The predominant method for obtaining silicon carbide crystals is physical vapor deposition. The method uses a silicon carbide wafer as a seed crystal and the carbon face of the wafer as a growth face, and dislocations in the wafer may extend into the crystal during crystal growth. Wherein the basal plane dislocation has a great influence on the bipolar silicon carbide device, the density of the basal plane dislocation in the crystal needs to be reduced as much as possible.
Disclosure of Invention
In order to reduce the density of basal plane dislocations in the crystal, the invention provides a method for processing a silicon carbide seed crystal, which comprises the following steps:
putting a certain amount of strong base solid into the bottom of the crucible;
placing a silicon carbide wafer above a strong base solid in a crucible;
heating the crucible to enable the strong base solid to form alkali steam, and carrying out alkali steam corrosion on the silicon carbide wafer to form corrosion pits on the carbon surface of the silicon carbide wafer;
then putting a certain amount of strong base solid into the crucible, and heating to a set temperature to enable the strong base solid to form molten base;
immersing the silicon carbide wafer subjected to alkali vapor corrosion into the molten alkali, and keeping the temperature for a certain time to flatten the carbon surface of the silicon carbide wafer;
and taking out the silicon carbide wafer, repeatedly rinsing the silicon carbide wafer by using deionized water, and blow-drying the silicon carbide wafer to form the silicon carbide seed crystal.
Optionally, the strong base solid is a sodium hydroxide solid or a potassium hydroxide solid.
Optionally, the crucible is a nickel crucible, a nickel mesh is placed in the crucible, and the silicon carbide wafer is placed on the surface of the nickel mesh.
Optionally, the temperature range of the alkali steam corrosion is 900-1100 ℃, and the time range of the alkali steam corrosion is 5-20 minutes.
Optionally, the set temperature for forming the molten alkali is 450-600 ℃, and the heat preservation time of the molten corrosion is 5-90 minutes.
Optionally, the thickness of the molten alkali etching to the carbon surface of the silicon carbide wafer ranges from 20 micrometers to 50 micrometers.
Optionally, the silicon carbide wafer is dried by using a nitrogen gun in the drying process.
The invention also provides a method for growing silicon carbide crystals, which comprises the following steps:
putting a certain amount of strong base solid into the bottom of a crucible;
placing a silicon carbide wafer above a strong base solid in a crucible;
heating the crucible to enable the strong base solid to form alkali steam, and carrying out alkali steam corrosion on the silicon carbide wafer to form corrosion pits on the carbon surface of the silicon carbide wafer;
putting a certain amount of strong base solid into a crucible, and heating to a set temperature to enable the strong base solid to form molten base;
immersing the silicon carbide wafer subjected to alkali vapor corrosion into the molten alkali, and preserving heat for a certain time to enable the carbon surface of the silicon carbide wafer to be flat;
taking out the silicon carbide wafer, repeatedly rinsing the silicon carbide wafer by using deionized water, and drying the silicon carbide wafer by blowing to form silicon carbide seed crystals;
and growing a silicon carbide crystal on the surface of the carbon surface of the silicon carbide seed crystal.
Optionally, the temperature range of the alkali vapor etching of the silicon carbide wafer is 900-1100 ℃, and the time range of the alkali vapor etching is 5-20 minutes.
Optionally, the set temperature for forming the molten alkali is 450-600 ℃, the heat preservation time of the molten corrosion is 5-90 minutes, and the thickness of the carbon surface of the silicon carbide wafer corroded by the molten alkali corrosion is 20-50 micrometers.
In summary, the advantages and beneficial effects of the invention are as follows:
the invention provides a processing method of a silicon carbide seed crystal and a growing method of the silicon carbide crystal, which are characterized in that alkali steam corrosion and fused alkali corrosion are sequentially carried out on the silicon carbide crystal, so that the dislocation of a base plane of a carbon surface of the silicon carbide crystal is converted into a corrosion pit, the silicon carbide seed crystal with a smoother surface is obtained at the same time, and the finally obtained silicon carbide seed crystal is used for growing the silicon carbide crystal.
If the carbon surface of the silicon carbide wafer is subjected to only alkali vapor etching, although etching pits can be formed at the dislocation positions of the basal plane of the carbon surface, the carbon surface of the silicon carbide seed crystal is uneven and is difficult to be used as a seed crystal for growing the silicon carbide crystal; the silicon carbide wafer obtained after the alkali vapor etching is subjected to the molten alkali etching continuously, and the silicon carbide wafer is subjected to the isotropic etching due to the molten alkali etching, so that the carbon surface of the silicon carbide wafer is finally etched by controlling the time of the molten alkali etching, and the condition required by the growth of the silicon carbide crystal is met. The growth of the silicon carbide crystal is carried out by utilizing the silicon carbide seed crystal, because the exposed etch pits are acted by enhanced mirror image force during the crystal growth, the exposed etch pits can be forcibly combined, and simultaneously the basal plane dislocation is converted into the threading edge dislocation, thereby obtaining the crystal with low basal plane dislocation density.
Drawings
FIG. 1 is a schematic illustration of the carbon side of a fused alkali etched silicon carbide wafer of a conventional silicon carbide wafer;
FIG. 2 is a schematic illustration of the carbon side of an alkali vapor etched silicon carbide wafer of a conventional silicon carbide wafer;
FIG. 3 is a flow chart illustrating a method of processing a silicon carbide wafer in accordance with an embodiment of the present invention;
FIG. 4 is a schematic representation of a carbon surface after treatment by a method of treating a silicon carbide wafer in accordance with an embodiment of the present invention;
FIG. 5 is a flow chart of a method for growing a silicon carbide crystal according to an embodiment of the invention;
FIG. 6 shows an electron micrograph of a cross-section of a silicon carbide crystal after a method of growing the silicon carbide crystal according to an embodiment of the invention.
Detailed Description
The inventors have discovered that by alkaline etching, etch pits are formed and revealed at the sites of basal plane dislocations of a silicon carbide wafer, which during growth of the silicon carbide crystal are forced to merge into threading edge dislocations, subject to enhanced mirror image forces, thereby providing a silicon carbide crystal with a low basal plane dislocation density.
However, the above method requires that the basal plane dislocation of the carbon surface of the silicon carbide wafer is etched to form an etch pit, and other positions of the carbon surface of the silicon carbide wafer are kept flat, so that the subsequent crystal growth can be carried out. In the conventional etching process, please refer to fig. 1, the molten alkali etching cannot obtain an etch pit of basal plane dislocation on the carbon surface of the silicon carbide wafer; referring to fig. 2, the carbon side of the alkali vapor etched silicon carbide wafer can be etched pits, but the carbon side of the silicon carbide wafer becomes too rough to be used for crystal growth.
The invention solves the problems that the carbon surface of the silicon carbide seed crystal can be simultaneously etched and leveled, so that the carbon surface of the silicon carbide seed crystal can be used as the growth surface of the silicon carbide crystal.
The present invention will be described in further detail below with reference to specific examples for facilitating understanding by those skilled in the art.
An embodiment of the present invention provides a method for processing a silicon carbide seed crystal, please refer to fig. 3, including:
step S10, putting a certain amount of strong base solid into the bottom of a crucible;
s20, placing the silicon carbide wafer above the strong base solid in the crucible;
s30, heating the crucible to enable the strong base solid to form alkali steam, and carrying out alkali steam corrosion on the silicon carbide wafer to form a corrosion pit on the carbon surface of the silicon carbide wafer;
s40, putting a certain amount of strong base solid into a crucible, and heating to a set temperature to enable the strong base solid to form molten base;
step S50, immersing the silicon carbide wafer corroded by the alkali steam into the molten alkali, and keeping the temperature for a certain time to enable the carbon surface of the silicon carbide wafer to be flat;
and S60, taking out the silicon carbide wafer, repeatedly rinsing the silicon carbide wafer by using deionized water, and drying the silicon carbide wafer by blowing to form the silicon carbide seed crystal.
Specifically, step S10 is performed, and a certain amount of strong base solid is placed at the bottom of the crucible.
In the embodiment of the invention, the strong base solid is sodium hydroxide solid, and in other embodiments, the strong base solid is potassium hydroxide solid.
In the present example, the amount of strong base solids was 5 grams of sodium hydroxide solids.
In the embodiment of the invention, the crucible is a nickel crucible, and a nickel net is placed in the crucible.
Step S20 is performed by placing the silicon carbide wafer above the strong base solid in the crucible.
In the embodiment of the invention, the silicon carbide wafer is a 4H silicon carbide wafer. In other embodiments, the silicon carbide wafer may also be a 6H silicon carbide wafer or other silicon carbide wafer.
In the embodiment of the invention, the silicon carbide wafer is placed on the surface of the nickel mesh, and the carbon surface of the silicon carbide wafer is opposite to the strong base solid at the bottom of the crucible.
In other embodiments, the silicon carbide wafer is placed on a nickel mesh surface with the carbon side of the silicon carbide wafer facing the strong base solid at the bottom of the crucible.
The silicon carbide wafer is supported by a nickel mesh placed in the crucible so that the silicon carbide wafer is placed above the strong base solid and does not directly contact the strong base solid.
And S30, heating the crucible to enable the strong base solid to form alkali steam, and performing alkali steam corrosion on the silicon carbide wafer to form corrosion pits on the carbon surface of the silicon carbide wafer.
Heating the crucible in a high-temperature furnace, wherein the temperature range of the alkali steam corrosion is 900-1100 ℃.
In the embodiment of the invention, the temperature of the alkali steam corrosion in the high-temperature furnace is 950 ℃.
In another embodiment of the present invention, the temperature of the high temperature furnace is 1050 ℃.
The time range of the alkali steam corrosion in the high-temperature furnace is 5 minutes to 20 minutes.
In the present example, the time for the alkali vapor etching was 10 minutes.
The strong alkali solid forms alkali steam under the high-temperature condition, and the silicon carbide wafer is subjected to alkali steam corrosion.
Because the base plane dislocation of the silicon carbide wafer can cause stress concentration around the base plane dislocation, after the silicon carbide wafer is subjected to alkali vapor etching, an etching pit is formed at the base plane dislocation position of the carbon surface of the silicon carbide wafer, the etching pit is influenced by enhanced mirror image force during the growth of the silicon carbide crystal, the etching pits can be forcibly merged, and the base plane dislocation is converted into the through type edge dislocation, so that the crystal with low base plane dislocation density is obtained.
Step S40 is executed, a certain amount of strong base solid is taken and put into the crucible, and the crucible is heated to the set temperature, so that the strong base solid forms molten base.
In the embodiment of the invention, the strong alkali solid is potassium hydroxide solid, and in other embodiments, the strong alkali solid is sodium hydroxide solid.
Wherein, in this example, the mass of the appropriate amount of strong base solid is 30 grams of potassium hydroxide solid.
The set temperature range for heating the strong alkali solid is 450-600 ℃.
In the embodiment of the invention, the set temperature is 540 ℃.
The strong base solid is heated at a set temperature so that the strong base solid becomes molten base.
And S50, immersing the silicon carbide wafer subjected to alkali vapor corrosion into the molten alkali, and keeping the temperature for a certain time to enable the carbon surface of the silicon carbide wafer to be flat.
The heat preservation time of the fusion corrosion is 5-90 minutes.
In the embodiment of the invention, the heat preservation time of the fusion corrosion is 60 minutes.
In another embodiment of the present invention, the heat preservation time of the molten corrosion is 30 minutes.
In the embodiment of the invention, the thickness of the molten alkali corrosion on the carbon surface of the silicon carbide wafer ranges from 20 micrometers to 50 micrometers.
The silicon carbide wafer is subjected to alkali vapor etching, although an etching pit is formed at a dislocation position of a basal plane of a carbon surface of the silicon carbide wafer, the carbon surface of the silicon carbide wafer is also uneven and is difficult to be used as a wafer for growing the silicon carbide wafer.
And S60, taking out the silicon carbide wafer, repeatedly rinsing the silicon carbide wafer by using deionized water, and drying the silicon carbide wafer by blowing to form the silicon carbide seed crystal.
In the embodiment of the invention, the silicon carbide wafer is dried by using a nitrogen gun in the drying process.
An embodiment of the present invention further provides a method for growing a silicon carbide crystal, please refer to fig. 5, which includes:
step S100, putting a certain amount of strong base solid into the bottom of a crucible;
s200, placing a silicon carbide wafer above a strong base solid in a crucible;
step S300, heating the crucible in a high-temperature furnace to enable the strong base solid to form alkali steam, and carrying out alkali steam corrosion on the silicon carbide wafer to form a corrosion pit on the carbon surface of the silicon carbide wafer;
step S400, putting a certain amount of strong base solid into a crucible, and heating to a set temperature to enable the strong base solid to form molten base;
step S500, immersing the silicon carbide wafer corroded by the alkali steam into the molten alkali, and preserving heat for a certain time to enable the carbon surface of the silicon carbide wafer to be flat;
s600, taking out the silicon carbide wafer, repeatedly rinsing the silicon carbide wafer by using deionized water, and drying the silicon carbide wafer by blowing to form a silicon carbide seed crystal;
and S700, growing a silicon carbide crystal on the surface of the carbon surface of the silicon carbide seed crystal.
In the embodiment of the invention, the temperature range of the alkali steam corrosion of the silicon carbide wafer is 900-1100 ℃, and the time range of the alkali steam corrosion is 5-20 minutes.
In the embodiment of the invention, the set temperature for forming the molten alkali is 450-600 ℃, the heat preservation time of the molten corrosion is 5-90 minutes, and the thickness of the carbon surface of the silicon carbide wafer corroded by the molten alkali corrosion is 20-50 micrometers.
When a silicon carbide crystal grows on the surface of the carbon surface of the silicon carbide seed crystal, the density of the base plane dislocation on the surface of the carbon surface of the silicon carbide seed crystal is reduced, the quality of the silicon carbide crystal is improved, and the yield of the semiconductor device is improved.
The basal plane dislocation is approximately parallel to the surface of the silicon carbide seed crystal, the threading edge dislocation is vertical to the surface of the silicon carbide seed crystal, the basal plane dislocation and the threading edge dislocation have the same Bernoulli vector and are expression forms of the same structure on different crystal planes, so the basal plane dislocation can be converted to the threading edge dislocation.
In the conventional crystal growth process, basal plane dislocations in the silicon carbide seed crystal continue to grow along the original dislocation line direction, the elastic energy is greatly increased, and the energy can be reduced through the transformation from the basal plane dislocations to the threading edge dislocations, namely, the basal plane dislocations can be transformed to the threading edge dislocations, but the transformation from the basal plane dislocations to the threading edge dislocations randomly occurs at any period of growth and cannot be controlled.
The basal plane dislocations in a silicon carbide crystal are broken down into two incomplete dislocations connected by a stacking fault. Not all dislocations can not be converted into a longitudinal growth direction, and the influence of basal plane dislocations on the silicon carbide crystal in the growth process of the silicon carbide crystal cannot be avoided. To achieve the conversion of the basal plane dislocations into threading edge dislocations, it is necessary to have less than all the dislocations recombine. However, on the surface of the carbon face of the flat silicon carbide seed crystal, the silicon carbide crystal grows in a layered manner, and the incorporation of all dislocations does not occur randomly at any time during the growth of the silicon carbide, and thus the control cannot be carried out.
In the embodiment of the invention, referring to fig. 6, a silicon carbide seed crystal for converting base plane dislocation into an etch pit is obtained by etching a carbon surface of a silicon carbide wafer with alkali vapor, the etch pit has a three-dimensional structure, a crystal plane in the etch pit is a high-index crystal plane, when a silicon carbide crystal grows on the carbon surface of the silicon carbide seed crystal, the high-index crystal plane in the etch pit grows towards the inner side of the etch pit along the side surface of the etch pit, the etch pit is finally filled, and when the etch pit is gradually filled, a merged dislocation line is finally obtained at a boundary of the crystal planes, so that the original base plane dislocation growing transversely is converted into the edge dislocation growing longitudinally by using the action of mirror image, thereby promoting the conversion from the base plane dislocation to the threading edge dislocation, improving the conversion probability from the base plane dislocation to the threading edge dislocation, and effectively reducing the base plane dislocation density of the silicon carbide crystal.
Finally, it is to be noted that any modifications or equivalent substitutions of some or all of the features of the method according to the invention and of the technical solutions of the examples described above may be made without departing substantially from the corresponding technical solutions of the invention, and the resulting material falls within the framework of the device according to the invention and the scope of the claims of the embodiments described above.
Claims (10)
1. A method of processing a silicon carbide seed crystal, comprising:
putting a certain amount of strong base solid into the bottom of a crucible;
placing a silicon carbide wafer above a strong base solid in a crucible;
heating the crucible to enable the strong base solid to form alkali steam, and carrying out alkali steam corrosion on the silicon carbide wafer to form corrosion pits on the carbon surface of the silicon carbide wafer;
then putting a certain amount of strong base solid into the crucible, and heating to a set temperature to enable the strong base solid to form molten base;
immersing the silicon carbide wafer subjected to alkali vapor corrosion into the molten alkali, and keeping the temperature for a certain time to flatten the carbon surface of the silicon carbide wafer;
and taking out the silicon carbide wafer, repeatedly rinsing the silicon carbide wafer by using deionized water, and drying the silicon carbide wafer by blowing to form the silicon carbide seed crystal.
2. A method for seed treatment of silicon carbide as set forth in claim 1 wherein the strong base solid is sodium hydroxide solid or potassium hydroxide solid.
3. A method for processing a silicon carbide seed crystal as claimed in claim 1, wherein the crucible is a nickel crucible having a nickel mesh placed therein and the silicon carbide wafer is placed on the surface of the nickel mesh.
4. A method of seed treatment of silicon carbide according to claim 1 wherein the temperature of the alkali vapor etching ranges from 900 ℃ to 1100 ℃ and the time of the alkali vapor etching ranges from 5 minutes to 20 minutes.
5. A method of seed treatment of silicon carbide according to claim 1 wherein the set temperature for forming the molten alkali is in the range of 450 ℃ to 600 ℃ and the holding time for the molten etching is in the range of 5 minutes to 90 minutes.
6. A method of handling a silicon carbide seed crystal according to claim 1 wherein the molten alkali etch etches the carbon face of the silicon carbide wafer to a thickness in the range of 20 microns to 50 microns.
7. A method for seed crystal treatment of silicon carbide as set forth in claim 1, wherein the blow drying process of the silicon carbide wafer is blow-dried using a nitrogen gun.
8. A method of growing a silicon carbide crystal, comprising:
putting a certain amount of strong base solid into the bottom of the crucible;
placing a silicon carbide wafer above a strong base solid in a crucible;
heating the crucible to enable the strong base solid to form alkali steam, and performing alkali steam corrosion on the silicon carbide wafer to form a corrosion pit on the carbon surface of the silicon carbide wafer;
putting a certain amount of strong base solid into a crucible, and heating to a set temperature to enable the strong base solid to form molten base;
immersing the silicon carbide wafer subjected to alkali vapor corrosion into the molten alkali, and preserving heat for a certain time to enable the carbon surface of the silicon carbide wafer to be flat;
taking out the silicon carbide wafer, repeatedly rinsing the silicon carbide wafer by using deionized water, and drying the silicon carbide wafer by blowing to form silicon carbide seed crystals;
and growing a silicon carbide crystal on the surface of the carbon surface of the silicon carbide seed crystal.
9. The method for growing silicon carbide crystals according to claim 8, wherein the temperature of the alkali vapor etching of the silicon carbide wafer ranges from 900 ℃ to 1100 ℃, and the time of the alkali vapor etching ranges from 5 minutes to 20 minutes.
10. The method for growing silicon carbide crystals according to claim 8, wherein the set temperature for forming the molten alkali is in the range of 450 ℃ to 600 ℃, the holding time for the molten corrosion is in the range of 5 minutes to 90 minutes, and the thickness of the molten alkali corrosion on the carbon surface of the silicon carbide crystal is in the range of 20 micrometers to 50 micrometers.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211523460.3A CN115595663B (en) | 2022-12-01 | 2022-12-01 | Treatment method of silicon carbide seed crystal and growth method of silicon carbide crystal |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211523460.3A CN115595663B (en) | 2022-12-01 | 2022-12-01 | Treatment method of silicon carbide seed crystal and growth method of silicon carbide crystal |
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| CN115595663A true CN115595663A (en) | 2023-01-13 |
| CN115595663B CN115595663B (en) | 2023-07-25 |
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