CN113061985B - Method for improving crystal quality by adjusting carbon-silicon ratio distribution - Google Patents
Method for improving crystal quality by adjusting carbon-silicon ratio distribution Download PDFInfo
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- CN113061985B CN113061985B CN202110302502.XA CN202110302502A CN113061985B CN 113061985 B CN113061985 B CN 113061985B CN 202110302502 A CN202110302502 A CN 202110302502A CN 113061985 B CN113061985 B CN 113061985B
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- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 title claims abstract description 26
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 151
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 78
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims abstract description 71
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 68
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- 239000000843 powder Substances 0.000 claims description 25
- 229910052786 argon Inorganic materials 0.000 claims description 17
- 239000002245 particle Substances 0.000 claims description 15
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- 239000011159 matrix material Substances 0.000 claims description 2
- 238000005087 graphitization Methods 0.000 abstract description 4
- 238000002360 preparation method Methods 0.000 abstract description 2
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 7
- 229910052710 silicon Inorganic materials 0.000 description 7
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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
- C30B23/002—Controlling or regulating
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B28/00—Production of homogeneous polycrystalline material with defined structure
- C30B28/12—Production of homogeneous polycrystalline material with defined structure directly from the gas state
-
- 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
Abstract
The invention relates to a method for improving the crystal quality by adjusting the carbon-silicon ratio distribution, belonging to the technical field of silicon carbide crystal preparation. In order to solve the problem of uneven distribution of carbon-silicon ratio when a PVT method is used for preparing the silicon carbide crystal, the invention provides a method for improving the crystal quality by adjusting the distribution of the carbon-silicon ratio, silicon carbide powder is added into a graphite crucible, an auxiliary carbon source is inserted into the center of the silicon carbide powder, a seed crystal is bonded on a graphite crucible cover, and the graphite crucible body and the graphite crucible cover are combined to carry out the growth of the silicon carbide crystal so as to obtain the silicon carbide crystal; the auxiliary carbon source comprises a long-strip-shaped central base body and a plurality of fins arranged on the outer surface of the central base body, the length directions of the fins are parallel to the length direction of the central base body, and a conical insertion portion is arranged at the bottom of the central base body. The invention balances the carbon supply of the whole seed crystal growth surface, realizes the balanced and rapid growth of the crystal and inhibits the graphitization caused by the balanced reverse movement of the crystal growth.
Description
Technical Field
The invention belongs to the technical field of silicon carbide crystal preparation, and particularly relates to a method for improving the crystal quality by adjusting the carbon-silicon ratio distribution.
Background
The silicon carbide serving as a third-generation semiconductor material has the characteristics of wide forbidden band, high breakdown field strength, high thermal conductivity and the like, and can be applied to the fields of new energy automobiles, photovoltaic inverters, charging piles and the like to achieve the aims of reducing power consumption, improving switching frequency, reducing overall cost and the like.
Since silicon carbide decomposes at normal pressure before being heated to the melting point, a method similar to the growth of silicon crystals cannot be used directly. At present, the growth methods of the large-size silicon carbide crystal mainly comprise two methods: one is to add a flux to form a melt containing silicon carbide and grow crystals using the melt. The other method is a PVT method, which is to put silicon carbide powder into the bottom of a crucible, stick silicon carbide seed crystals on the top of the crucible, then vacuumize a reaction container, heat the reaction container to about 1000 ℃ and keep the vacuum degree during the process. Then filling a proper amount of argon, further heating to about 2000 ℃, decomposing the raw materials under the conditions of high temperature and inert atmosphere, and depositing the gas phase generated after decomposition on the seed crystal under the control of temperature gradient to grow the crystal.
Since the first method is accompanied by a large number of crystal defects due to the introduction of a cosolvent into the crystals to be produced, the second method, which is currently used in mass production, is the PVT method.
During the growth process of the silicon carbide crystal, carbon and silicon are not decomposed into gas phase in an equimolar ratio, the content of silicon in gas phase components is higher, and the powder is gradually graphitized due to the deposition of carbon. Silicon in the gas phase reacts with the graphite crucible at high temperature to generate SiC2And (3) in the carbon-rich gas phase, the process provides certain carbon atoms for the growth of the seed crystal, so that the crucible becomes an important carbon source in the crystal growth process. Also, since this process is consumable, the graphite crucible needs to be replaced after a certain number of experiments.
SiC mentioned in the above-mentioned Process2The partial pressure of the carbon-rich gas phase is an important control condition in the crystal growth process, when the partial pressure is lower, the crystal growth speed is slowed down, and when the partial pressure is lower than the lowest equilibrium partial pressure, the crystal stops growing, and even the crystal is decomposed to cause the graphitization of the crystal. The crystal grown under certain experimental conditions exhibited dishing due to SiC near the crucible wall2Equi-carbon enrichment causes the edges of the crystal to grow faster than the middle. Since the wafers currently processed from the crystal are all round, the concave-in-the-middle crystal processing process is wasteful to a large extent.
There are patents or articles which propose increasing the SiC in the gas phase by adding activated carbon powder to the powder2To promote crystal growth, but this method does not address SiC caused by the reaction of Si gas with the crucible wall2The problem of uneven distribution is solved, and because the activated carbon powder is fine, sometimes, the grown crystal has carbon inclusion due to the transportation and entrainment of gas, and the quality of the silicon carbide crystal is influenced.
Disclosure of Invention
In order to solve the problem of uneven carbon-silicon ratio distribution when the silicon carbide crystal is prepared by a PVT method, the invention provides a method for improving the crystal quality by adjusting the carbon-silicon ratio distribution.
The technical scheme of the invention is as follows:
adding silicon carbide powder into a graphite crucible, inserting an auxiliary carbon source into the center of the silicon carbide powder, adhering seed crystals to a graphite crucible cover, combining the graphite crucible body and the graphite crucible cover, and growing silicon carbide crystals to obtain silicon carbide crystals; the auxiliary carbon source comprises a strip-shaped central base body and a plurality of fins arranged on the outer surface of the central base body, the length directions of the fins are parallel to the length direction of the central base body, and a conical insertion part is arranged at the bottom of the central base body.
Furthermore, the auxiliary carbon source is made of graphite or amorphous carbon, the impurity content is less than 100ppm, the porosity is 10-40%, and the average sintered particle diameter is 10-200 μm.
Furthermore, the number of the fins is 0, 3, 4, 5 or 6, and included angles among the fins are equal.
Furthermore, when the number of the fins is 0, the central base body is a hollow cylinder with a circular cross section.
Further, when the number of the fins is 3, 4, 5 or 6, the ratio of the diameter of a circumscribed circle of the cross section of each fin to the inner diameter of the crucible is 1: 1.5-1: 4.
Furthermore, the length of the central base body is equal to that of the fins, and the length of the central base body is 0.1-0.8 time of the distance between the upper surface of the powder and the cavity between the crucible cover and the central base body.
Furthermore, the length of the conical insertion part is 0.1-0.5 times of the thickness of the powder.
Further, the particle size of the silicon carbide powder is 100 microns.
Further, the specific conditions for the growth of the silicon carbide crystal are that the interior of a graphite crucible is vacuumized to 4-10 Torr, the temperature is raised to 700 ℃ at 300 ℃/h, the heat preservation and pressure maintenance are carried out for 5h, argon is filled to 0.1atm, the temperature is raised to 2200 ℃ at 300 ℃/h continuously, the heat preservation and pressure maintenance are carried out for 40h, the growth of the silicon carbide crystal is completed, the silicon carbide crystal is naturally cooled to 500 ℃, and the argon is filled to cool to the room temperature.
The invention has the beneficial effects that:
the method for improving the crystal quality by adjusting the carbon-silicon ratio distribution improves the SiC of the central area of the corresponding seed crystal by inserting a carbon-containing component in the middle of the powder area2The content of the carbon-rich components is equal to balance the supply of carbon on the whole growth surface of the seed crystal, so that each part of the growth surface can obtain enough carbon source as far as possible, and further, the balanced and rapid growth of the crystal is realized. Meanwhile, the addition of the carbon-containing part can also improve the total carbon content of the gas phase in the cavity at the upper part of the powder, and inhibit graphitization caused by the reverse movement of crystal growth balance.
The invention inserts carbon-containing components at specific positions, which can solve the problem of poor crystal growth shape caused by uneven distribution of carbon-containing components which cannot be solved by directly mixing activated carbon powder or graphite powder into powder. In addition, because the structure of the carbon-containing part is compact, the generation of carbon inclusion caused by powder dispersion after the carbon-containing powder is added can not occur. In addition, graphite pieces with different shapes can be used according to the requirements of the user.
Drawings
FIG. 1 is a schematic diagram of the method of using an auxiliary carbon source for silicon carbide crystal growth according to the present invention;
FIG. 2 is a side view of an auxiliary carbon source with 6 fins as provided in example 1;
FIG. 3 is a top view of the supplemental carbon source with 6 fins provided in example 1;
FIG. 4 is a top view of the supplemental carbon source with 4 fins provided in example 2;
FIG. 5 is a top view of the supplemental carbon source with 3 fins provided in example 3;
FIG. 6 is a carbon-silicon distribution diagram in a graphite crucible when an auxiliary carbon source without fins provided in example 4 is used for growing silicon carbide crystals;
FIG. 7 is a carbon-silicon distribution diagram in a graphite crucible when an auxiliary carbon source with 6 fins provided in example 1 is used for growing silicon carbide crystals;
FIG. 8 is a perspective view showing the distribution of silicon and carbon in a graphite crucible when an auxiliary carbon source with 6 fins provided in example 1 is used for silicon carbide crystal growth;
FIG. 9 is a carbon-silicon distribution diagram in a graphite crucible in comparative example 1 for silicon carbide crystal growth without using an auxiliary carbon source.
Detailed Description
The technical solutions of the present invention are further described below with reference to the embodiments, but the present invention is not limited thereto, and any modifications or equivalent substitutions made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention should be covered in the protection scope of the present invention. The process equipment or apparatus not specifically mentioned in the following examples are conventional in the art, and if not specifically mentioned, the raw materials and the like used in the examples of the present invention are commercially available; unless otherwise specified, all technical means used in the examples of the present invention are conventional means well known to those skilled in the art.
Example 1
The embodiment provides a method for improving the crystal quality by adjusting the carbon-silicon ratio distribution.
The embodiment provides an auxiliary carbon source 5, which is prepared from graphite, wherein the specific type of the graphite is SIGRAFINE R6340 manufactured by sgl carbon corporation, the impurity content is less than 100ppm, the porosity is 10-40%, and the average sintered particle diameter is 10-200 μm.
The auxiliary carbon source 5 comprises a strip-shaped central base 501 and 6 fins 502 arranged on the outer surface of the central base 501, included angles between the 6 fins 502 are equal, the length direction of each fin 502 is parallel to that of the central base 501, and the ratio of the diameter of a circumscribed circle of the cross section of each fin 502 to the inner diameter of the crucible is 1: 1.5. The length of the central base 501 is equal to that of the fins 502, and the lengths of the central base 501 and the fins are 0.5 times of the distance between the upper surface of the powder and the cavity between the crucible covers.
The bottom of the central substrate 501 of the auxiliary carbon source 5 is provided with a conical insertion part 503, and the length of the conical insertion part 503 is 0.5 times of the thickness of the powder.
The specific method for improving the crystal quality by adjusting the carbon-silicon ratio distribution in the embodiment is as follows:
adding 400g of silicon carbide powder 4 with the particle size of 100 mu m into a graphite crucible, inserting an auxiliary carbon source 5 into the center position of the silicon carbide powder 4, bonding a seed crystal 3 on a graphite crucible cover 1, combining a graphite crucible body 2 and the graphite crucible cover 1, vacuumizing the interior of the graphite crucible to 4-10 Torr, heating to 700 ℃ at 300 ℃/h, keeping the temperature and pressure for 5h, filling argon to 0.1atm, continuing heating to 2200 ℃ at 300 ℃/h, keeping the temperature and pressure for 40h to finish the growth of the silicon carbide crystal, naturally cooling to 500 ℃, filling argon and cooling to room temperature to obtain the silicon carbide crystal with the thickness of 3.51cm and no concave shape in the middle.
FIG. 7 is a graph showing the distribution of carbon and silicon in a graphite crucible during the growth of the silicon carbide crystal according to the embodiment; FIG. 8 is a perspective view showing the distribution of carbon and silicon in the graphite crucible during the growth of the silicon carbide crystal according to the embodiment; as can be seen from the figure, SiC in the central region of the seed crystal in the graphite crucible after insertion of the auxiliary carbon source2The content of the carbon-rich components is improved, so that the carbon supply of the whole seed crystal growth surface is balanced, each part of the growth surface obtains enough carbon source as far as possible, and further, the balanced and rapid growth of the crystal is realized. Meanwhile, the addition of the auxiliary carbon source also improves the total carbon content of the gas phase in the cavity at the upper part of the powder, thereby inhibiting the graphitization caused by the reverse movement of the crystal growth balance.
The invention solves the problem of poor crystal growth shape caused by uneven distribution of carbon-containing components which cannot be solved by directly mixing activated carbon powder or graphite powder into powder by inserting the carbon-containing component into a specific position. In addition, because the structure of the carbon-containing part is compact, the generation of carbon inclusion caused by powder dispersion after the carbon-containing powder is added can not occur. In addition, graphite pieces with different shapes can be used according to the requirements of the user.
Example 2
The embodiment provides a method for improving the crystal quality by adjusting the carbon-silicon ratio distribution.
The embodiment provides an auxiliary carbon source 5 which is prepared from graphite serving as a material, wherein the specific type of the graphite is SIGRAFINE R6340 produced by sgl carbon company, the impurity content is less than 100ppm, the porosity is 10-40%, and the average sintered particle diameter is 10-200 μm.
The auxiliary carbon source 5 comprises a strip-shaped central base 501 and 4 fins 502 arranged on the outer surface of the central base 501, included angles between the 4 fins 502 are equal, the length direction of each fin 502 is parallel to that of the central base 501, and the ratio of the diameter of a circumscribed circle of the cross section of each fin 502 to the inner diameter of the crucible is 1: 2. The length of the central base 501 is equal to that of the fins 502, and the lengths of the central base 501 and the fins are 0.1 time of the distance between the upper surface of the powder and the cavity of the crucible cover.
The bottom of the central base 501 of the auxiliary carbon source 5 is provided with a conical insertion part 503, and the length of the conical insertion part 503 is 0.1 time of the thickness of the powder.
The specific method for improving the crystal quality by adjusting the carbon-silicon ratio distribution in the embodiment is as follows:
adding 400g of silicon carbide powder 4 with the particle size of 100 mu m into a graphite crucible, inserting an auxiliary carbon source 5 into the center position of the silicon carbide powder 4, bonding a seed crystal 3 on a graphite crucible cover 1, combining a graphite crucible body 2 and the graphite crucible cover 1, vacuumizing the interior of the graphite crucible to 4-10 Torr, heating to 700 ℃ at 300 ℃/h, preserving heat and pressure for 5h, filling argon to 0.1atm, continuing heating to 2200 ℃ at 300 ℃/h, preserving heat and pressure for 40h to finish the growth of the silicon carbide crystal, naturally cooling to 500 ℃, filling argon and cooling to room temperature to obtain the silicon carbide crystal.
Example 3
The embodiment provides a method for improving the crystal quality by adjusting the carbon-silicon ratio distribution.
The embodiment provides an auxiliary carbon source 5, which is prepared from graphite, wherein the specific type of the graphite is SIGRAFINE R6340 manufactured by sgl carbon corporation, the impurity content is less than 100ppm, the porosity is 10-40%, and the average sintered particle diameter is 10-200 μm.
The auxiliary carbon source 5 comprises a strip-shaped central base 501 and 3 fins 502 arranged on the outer surface of the central base 501, included angles between the 3 fins 502 are equal, the length direction of each fin 502 is parallel to that of the central base 501, and the ratio of the diameter of a circumscribed circle of the cross section of each fin 502 to the inner diameter of the crucible is 1: 3. The central matrix 501 and the fins 502 are equal in length and are 0.3 times the distance between the upper surface of the powder and the cavity between the crucible covers.
The bottom of the central substrate 501 of the auxiliary carbon source 5 is provided with a conical insertion part 503, and the length of the conical insertion part 503 is 0.3 times of the thickness of the powder.
The specific method for improving the crystal quality by adjusting the carbon-silicon ratio distribution in the embodiment is as follows:
adding 400g of silicon carbide powder 4 with the particle size of 100 mu m into a graphite crucible, inserting an auxiliary carbon source 5 into the center position of the silicon carbide powder 4, bonding a seed crystal 3 on a graphite crucible cover 1, combining a graphite crucible body 2 and the graphite crucible cover 1, vacuumizing the interior of the graphite crucible to 4-10 Torr, heating to 700 ℃ at 300 ℃/h, keeping the temperature and pressure for 5h, filling argon to 0.1atm, continuing heating to 2200 ℃ at 300 ℃/h, keeping the temperature and pressure for 40h to finish the growth of the silicon carbide crystal, naturally cooling to 500 ℃, filling argon and cooling to room temperature to obtain the silicon carbide crystal.
Example 4
The embodiment provides a method for improving the crystal quality by adjusting the carbon-silicon ratio distribution.
The embodiment provides an auxiliary carbon source 5, which is prepared from graphite, wherein the specific type of the graphite is SIGRAFINE R6340 manufactured by sgl carbon corporation, the impurity content is less than 100ppm, the porosity is 10-40%, and the average sintered particle diameter is 10-200 μm.
The auxiliary carbon source provided by the embodiment is only a strip-shaped central base 501 without fins, the central base 501 is a hollow cylinder with a circular cross section, and the length of the central base 501 is 0.8 times of the distance between the upper surface of the powder and the cavity between the crucible covers.
The bottom of the central substrate 501 of the auxiliary carbon source 5 is provided with a conical insertion part 503, and the length of the conical insertion part 503 is 0.4 times of the thickness of the powder.
The specific method for improving the crystal quality by adjusting the carbon-silicon ratio distribution in the embodiment is as follows:
adding 400g of silicon carbide powder 4 with the particle size of 100 mu m into a graphite crucible, inserting an auxiliary carbon source 5 into the center position of the silicon carbide powder 4, bonding a seed crystal 3 on a graphite crucible cover 1, combining a graphite crucible body 2 and the graphite crucible cover 1, vacuumizing the interior of the graphite crucible to 4-10 Torr, heating to 700 ℃ at 300 ℃/h, keeping the temperature and pressure for 5h, filling argon to 0.1atm, continuing heating to 2200 ℃ at 300 ℃/h, keeping the temperature and pressure for 40h to finish the growth of the silicon carbide crystal, naturally cooling to 500 ℃, filling argon and cooling to room temperature to obtain the silicon carbide crystal.
Example 5
The embodiment provides a method for improving the crystal quality by adjusting the carbon-silicon ratio distribution.
The embodiment provides an auxiliary carbon source 5 which is prepared from graphite serving as a material, wherein the specific type of the graphite is SIGRAFINE R6340 produced by sgl carbon company, the impurity content is less than 100ppm, the porosity is 10-40%, and the average sintered particle diameter is 10-200 μm.
The auxiliary carbon source 5 comprises a strip-shaped central base 501 and 5 fins 502 arranged on the outer surface of the central base 501, included angles between the 5 fins 502 are equal, the length direction of each fin 502 is parallel to that of the central base 501, and the ratio of the diameter of a circumscribed circle of the cross section of each fin 502 to the inner diameter of the crucible is 1: 4. The length of the central base 501 is equal to that of the fins 502, and the lengths of the central base 501 and the fins are 0.6 times of the distance between the upper surface of the powder and the cavity between the crucible covers.
The bottom of the central base 501 of the auxiliary carbon source 5 is provided with a conical insertion part 503, and the length of the conical insertion part 503 is 0.2 times of the thickness of the powder.
The specific method for improving the crystal quality by adjusting the carbon-silicon ratio distribution in the embodiment is as follows:
adding 400g of silicon carbide powder 4 with the particle size of 100 mu m into a graphite crucible, inserting an auxiliary carbon source 5 into the center position of the silicon carbide powder 4, bonding a seed crystal 3 on a graphite crucible cover 1, combining a graphite crucible body 2 and the graphite crucible cover 1, vacuumizing the interior of the graphite crucible to 4-10 Torr, heating to 700 ℃ at 300 ℃/h, preserving heat and pressure for 5h, filling argon to 0.1atm, continuing heating to 2200 ℃ at 300 ℃/h, preserving heat and pressure for 40h to finish the growth of the silicon carbide crystal, naturally cooling to 500 ℃, filling argon and cooling to room temperature to obtain the silicon carbide crystal.
Comparative example 1
The method for growing the silicon carbide crystal by using the auxiliary carbon source is as follows: adding 400g of silicon carbide powder 4 with the particle size of 100 mu m into a graphite crucible, adhering a seed crystal 3 on a graphite crucible cover 1, combining a graphite crucible body 2 and the graphite crucible cover 1, vacuumizing the interior of the graphite crucible to 4-10 Torr, heating to 700 ℃ at 300 ℃/h, keeping the temperature and pressure for 5h, filling argon to 0.1atm, continuing heating to 2200 ℃ at 300 ℃/h, keeping the temperature and pressure for 40h to finish the growth of the silicon carbide crystal, naturally cooling to 500 ℃, filling argon and cooling to room temperature to obtain the silicon carbide crystal with the thickness of 3.29 cm.
FIG. 9 is a carbon-silicon distribution diagram in a graphite crucible during the growth of the silicon carbide crystal of the comparative example, wherein the carbon-silicon distribution in the crucible of the comparative example is not uniform because an auxiliary carbon source is not used, so that the crystal of the comparative example grows slowly compared with the method of example 1, and a concave shape exists in the middle of the generated crystal.
Claims (3)
1. A method for improving the crystal quality by adjusting the carbon-silicon ratio distribution is characterized in that silicon carbide powder (4) is added into a graphite crucible, an auxiliary carbon source (5) is inserted into the center of the silicon carbide powder (4), a seed crystal (3) is bonded on a graphite crucible cover (1), a graphite crucible body (2) and the graphite crucible cover (1) are combined, and the silicon carbide crystal is grown to obtain the silicon carbide crystal; the auxiliary carbon source (5) comprises a strip-shaped central base body (501) and a plurality of fins (502) arranged on the outer surface of the central base body (501), the length directions of the fins (502) are parallel to the length direction of the central base body (501), and a conical insertion part (503) is arranged at the bottom of the central base body (501);
Wherein the auxiliary carbon source is made of graphite or amorphous carbon, the impurity content is less than 100ppm, the porosity is 10-40%, and the average sintered particle diameter is 10-200 μm;
the number of the fins (502) in the auxiliary carbon source structure is 3, 4, 5 or 6, the ratio of the diameter of a circumscribed circle of the cross section of each fin (502) to the inner diameter of the crucible is 1: 1.5-1: 4, the lengths of the central matrix (501) and the fins (502) are equal and are 0.1-0.8 time of the distance between the upper surface of the powder and the cavity between the crucible covers, and the length of the insertion part (503) is 0.1-0.5 time of the thickness of the powder.
2. The method of claim 1, wherein the silicon carbide powder has a particle size of 100 μm.
3. The method for improving the crystal quality by adjusting the carbon-silicon ratio distribution according to claim 1, wherein the specific conditions for the growth of the silicon carbide crystal are that the inside of a graphite crucible is vacuumized to 4-10 Torr, the temperature is raised to 700 ℃ at 300 ℃/h, the temperature and pressure are kept for 5h, argon is filled to 0.1atm, the temperature is raised to 2200 ℃ at 300 ℃/h, the temperature and pressure are kept for 40h, the growth of the silicon carbide crystal is completed, the silicon carbide crystal is naturally cooled to 500 ℃, and the argon is filled to cool to the room temperature.
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| CN202110302502.XA CN113061985B (en) | 2021-03-22 | 2021-03-22 | Method for improving crystal quality by adjusting carbon-silicon ratio distribution |
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| CN202110302502.XA CN113061985B (en) | 2021-03-22 | 2021-03-22 | Method for improving crystal quality by adjusting carbon-silicon ratio distribution |
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| CN113061985A CN113061985A (en) | 2021-07-02 |
| CN113061985B true CN113061985B (en) | 2022-06-28 |
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Effective date of registration: 20231127 Address after: Building 3 and Building 4, No. 3088 Zhigu Fifth Street, Songbei District, Harbin City, Heilongjiang Province, 150000 Patentee after: Harbin Keyou Semiconductor Industry Equipment and Technology Research Institute Co.,Ltd. Address before: Room 302-2, building 16 (No. 1616, Chuangxin Road), Harbin Institute of technology coastal creative technology port and Internet of things technology R & D center, high tech Industrial Development Zone, Harbin, Heilongjiang Province Patentee before: Harbin Huaxing Soft Control Technology Co.,Ltd. |