CN116219538A - Silicon carbide seed crystal bonding and fixing method and structure - Google Patents

Silicon carbide seed crystal bonding and fixing method and structure Download PDF

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Publication number
CN116219538A
CN116219538A CN202310202623.6A CN202310202623A CN116219538A CN 116219538 A CN116219538 A CN 116219538A CN 202310202623 A CN202310202623 A CN 202310202623A CN 116219538 A CN116219538 A CN 116219538A
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silicon carbide
bonding
carbide seed
seed crystal
fixing
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王明华
朱鑫煌
蒋林
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Qianjing Semiconductor Quzhou Co ltd
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Qianjing Semiconductor Quzhou Co ltd
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    • CCHEMISTRY; METALLURGY
    • C30CRYSTAL GROWTH
    • C30BSINGLE-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
    • C30B23/00Single-crystal growth by condensing evaporated or sublimed materials
    • CCHEMISTRY; METALLURGY
    • C30CRYSTAL GROWTH
    • C30BSINGLE-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
    • C30B29/00Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10Inorganic compounds or compositions
    • C30B29/36Carbides
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product

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  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
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  • Inorganic Chemistry (AREA)
  • Ceramic Products (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Abstract

The invention discloses a silicon carbide seed crystal bonding and fixing method and a silicon carbide seed crystal bonding and fixing structure. The invention improves the firmness and stability of bonding, and is particularly suitable for bonding large-size silicon carbide seed wafers; because the bonding and fixing method does not introduce an adhesive, the polycrystalline silicon carbide ceramic block is used, and the thermal expansion coefficient difference between the polycrystalline silicon carbide ceramic block and the silicon carbide seed crystal is almost avoided at high temperature; compared with the traditional adhesive bonding, the adhesive has higher bonding strength and less risk of increasing seed crystal stress caused by the difference of thermal expansion coefficients at high temperature.

Description

Silicon carbide seed crystal bonding and fixing method and structure
Technical Field
The invention belongs to the technical field of growth of silicon carbide seed crystals, relates to a bonding method, and particularly relates to a bonding fixing method and a fixing structure of a silicon carbide seed crystal without an adhesive.
Background
The SiC monocrystal as the third generation wide bandgap semiconductor material has wide bandgap, high heat conductivity, high electron saturation and migration rate, high breakdown electric field and other features, and is ideal semiconductor material for producing photoelectronic device, high frequency high power device and high temperature electronic device.
At present, a PVT (physical vapor phase) method is mainly adopted for growing the silicon carbide single crystal, a silicon carbide seed crystal is fixed at the upper end of a crucible, a silicon carbide powder table is placed at the lower end of the crucible, and the silicon carbide powder table sublimates at a high temperature and then grows at the seed crystal at the upper end. Therefore, the fixation of the silicon carbide seed crystal has high influence on the crystal growth quality.
The traditional seed crystal bonding process mainly adopts glucose, resin, AB glue, graphite glue and other glue to bond a silicon carbide seed crystal sheet on a graphite support, the seed crystal fixing method can have the thermal expansion coefficient between a graphite material and the silicon carbide seed crystal, the thermal conductivity difference, the bonding non-uniformity, the certain corrosion effect of an adhesive on the bonding surface of the seed crystal, the great number of microtubule defects generated in the subsequent crystal growth caused by sublimation of the back surface of the seed crystal and the like, the seed crystal damage is caused, the seed wafer is dropped due to the poor bonding force, the stability of the crystal growth is influenced by glue bubbles, and the yield and quality of the silicon carbide crystal are finally influenced.
It is extremely important to stabilize the high quality silicon carbide seed crystal fixing technique.
Disclosure of Invention
The invention aims to overcome the defect that the stability of silicon carbide crystal growth is affected by the increase of seed crystal stress caused by the difference of thermal expansion coefficients at high temperature by adopting an adhesive for bonding in the traditional seed crystal bonding process.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a silicon carbide seed crystal bonding and fixing method comprises the following steps:
1) Pretreating the bonding surface of the silicon carbide seed wafer;
2) Pretreating the bonding material;
3) Placing the bonding surface of the silicon carbide seed crystal sheet obtained in the step 1) on the bonding material pretreated in the step 2) to enable the bonding surface and the bonding material to be in close contact;
4) Placing the silicon carbide seed wafer and the bonding material in the step 3) into a reaction furnace, reducing the pressure in the reaction furnace, heating in a protective gas atmosphere, and preserving heat after reaching a preset temperature so as to enable partial silicon carbide sublimation and recrystallization to occur between the silicon carbide seed wafer and the bonding material;
5) And cooling to room temperature along with the furnace, and taking out to obtain the silicon carbide seed crystal which is uniformly bonded.
In a preferred embodiment of the present invention, in step 1), the pretreatment is polishing, and the bonding surface is a silicon surface.
In a preferred embodiment of the present invention, in step 2), the bonding material is a polycrystalline silicon carbide ceramic block, and the pretreatment is polishing.
As a preferable scheme of the invention, in the step 4), the pressure in the reaction furnace is reduced to be that the pressure in the reaction furnace is firstly vacuumized to be less than 10 -3 Pa, and then introducing protective gas to maintain the pressure in the reaction furnace at 50-500Pa.
As a preferable scheme of the invention, in the step 4), the preset temperature is 1700-2000 ℃, and the heat preservation time is 1-3h.
As a preferable mode of the invention, the area of the bonding material is larger than or equal to the area of the silicon carbide seed wafer.
In a preferred embodiment of the present invention, in step 4), the shielding gas is argon or helium.
In a preferred embodiment of the present invention, in step 3), the center of the silicon carbide seed wafer and the center of the adhesive material are aligned.
As a preferred scheme of the invention, the requirements of the bonding surface of the silicon carbide seed crystal sheet are as follows: the curvature is less than or equal to 30 mu m, the warping degree is less than or equal to 40 mu m, and the roughness is less than or equal to 0.2nm.
The invention also provides a silicon carbide seed crystal fixing structure prepared by the fixing method.
Compared with the prior art, the invention has the following beneficial effects:
1) According to the invention, by utilizing the characteristic of sublimation of silicon carbide in a high-temperature low-pressure environment, the contact surface of the silicon carbide seed wafer and the polycrystalline silicon carbide ceramic block is subjected to partial silicon carbide sublimation recrystallization reaction, so that the silicon carbide seed wafer and the polycrystalline silicon carbide ceramic block are firmly adhered;
2) The invention uses the bonding process without adhesive, and the risk of increasing the seed crystal stress caused by the difference of thermal expansion coefficients at high temperature is smaller;
3) The method is simple, has simple steps, is particularly suitable for bonding large-size silicon carbide seed wafers, and can be realized only by the silicon carbide seed wafers and the polycrystalline silicon carbide ceramic blocks.
Drawings
Fig. 1 is a schematic diagram of the present invention.
In the figure, 1. Silicon carbide seed wafer; 2. polycrystalline silicon carbide ceramic blocks.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, the invention provides a silicon carbide seed crystal bonding and fixing method, which comprises the following steps:
1) The polishing treatment of the bonding surface of the silicon carbide seed wafer 1 is required to be: the curvature is less than or equal to 30 mu m, the warping degree is less than or equal to 40 mu m, and the roughness is less than or equal to 0.2nm;
2) Polishing the adhesive material;
3) Placing the bonding surface of the silicon carbide seed wafer 1 obtained in the step 1) on the bonding material pretreated in the step 2), wherein the center of the silicon carbide seed wafer and the center of the bonding material are positioned on the same straight line, so that the silicon carbide seed wafer and the bonding material are in close contact;
4) Placing the silicon carbide seed crystal sheet 1 and the bonding material in the step 3) into a reaction furnace, and vacuumizing the pressure in the reaction furnace to be less than 10 -3 Pa, then introducing protective gas argon or helium, maintaining the pressure in the reaction furnace at 50-500Pa, heating to 1700-2000 ℃, and preserving heat for 1-3h to enable partial silicon carbide sublimation and recrystallization to occur between the silicon carbide seed wafer and the bonding material;
5) And cooling to room temperature along with the furnace, and taking out to obtain the silicon carbide seed crystal which is uniformly bonded.
The bonding material is preferably a material having a thermal expansion coefficient similar to that of the silicon carbide seed crystal, such as the polycrystalline silicon carbide ceramic block 2; in order to facilitate the subsequent operation, the area of the polycrystalline silicon carbide ceramic block 2 is larger than or equal to the area of the silicon carbide seed wafer 1.
The polycrystalline silicon carbide ceramic block 2 has high thermal conductivity and high compactness, the high thermal conductivity can ensure the uniformity of axial temperature gradient and radial temperature, and the silicon carbide seed crystal sheet 1 and the polycrystalline silicon carbide ceramic block 2 are subjected to partial silicon carbide sublimation recrystallization reaction by the characteristic of silicon carbide sublimation under the environment of high temperature and low pressure, so that the silicon carbide seed crystal sheet 1 and the polycrystalline silicon carbide ceramic block 2 are firmly bonded.
Example 1
The embodiment provides a silicon carbide seed crystal bonding and fixing method, which comprises the following steps:
step 1: polishing the bonding surface (silicon surface) of the silicon carbide seed crystal sheet, wherein the bending degree Bow is less than or equal to 30um, the Warp degree Warp is less than or equal to 40um, and the roughness Ra is less than or equal to 0.2nm;
step 2: the polished surface of the polycrystalline silicon carbide ceramic block faces upwards;
step 3: placing the silicon carbide seed crystal piece in the step 1 on the polished surface of the polycrystalline silicon carbide ceramic block in the step 2 with the bonding surface (silicon surface) downwards, and tightly placing the bonding surface and the silicon surface;
step 4: placing the silicon carbide seed wafer and ceramic block assembly in the step 3 in a vacuum high-temperature furnace;
step 5: the pressure in the furnace is pumped to a higher vacuum state (generally less than 10 -3 Pa), inert gas protection is performed by using Ar gas, and the pressure is maintained at 100Pa;
step 6: starting a temperature raising program, raising the temperature to 1800 ℃ within 4 hours, and maintaining the temperature for 2 hours;
step 7: and taking out the seed crystal after the temperature is reduced to the room temperature, and obtaining a seed crystal finished product which is uniformly bonded.
Example 2
The embodiment provides a silicon carbide seed crystal bonding and fixing method, which comprises the following steps:
step 1: polishing the bonding surface (silicon surface) of the silicon carbide seed crystal sheet, wherein the bending degree Bow is less than or equal to 30um, the Warp degree Warp is less than or equal to 40um, and the roughness Ra is less than or equal to 0.2nm;
step 2: the polished surface of the polycrystalline silicon carbide ceramic block faces upwards;
step 3: placing the silicon carbide seed crystal piece in the step 1 on the polished surface of the polycrystalline silicon carbide ceramic block in the step 2 with the bonding surface (silicon surface) downwards, and tightly placing the bonding surface and the silicon surface;
step 4: placing the silicon carbide seed wafer and ceramic block assembly in the step 3 in a vacuum high-temperature furnace;
step 5: the pressure in the furnace is pumped to a higher vacuum state (generally less than 10 -3 Pa), inert gas protection is performed by using He gas, and the pressure is maintained at 50Pa;
step 6: starting a temperature raising program, raising the temperature to 1700 ℃ within 3 hours, and maintaining the temperature for 3 hours;
step 7: and taking out the seed crystal after the temperature is reduced to the room temperature, and obtaining a seed crystal finished product which is uniformly bonded.
Example 3
The embodiment provides a silicon carbide seed crystal bonding and fixing method, which comprises the following steps:
step 1: polishing the bonding surface (silicon surface) of the silicon carbide seed crystal sheet, wherein the bending degree Bow is less than or equal to 30um, the Warp degree Warp is less than or equal to 40um, and the roughness Ra is less than or equal to 0.2nm;
step 2: the polished surface of the polycrystalline silicon carbide ceramic block faces upwards;
step 3: placing the silicon carbide seed crystal piece in the step 1 on the polished surface of the polycrystalline silicon carbide ceramic block in the step 2 with the bonding surface (silicon surface) downwards, and tightly placing the bonding surface and the silicon surface;
step 4: placing the silicon carbide seed wafer and ceramic block assembly in the step 3 in a vacuum high-temperature furnace;
step 5: the pressure in the furnace is pumped to a higher vacuum state (generally less than 10 -3 Pa), inert gas protection is performed by using Ar gas, and the pressure is maintained at 500Pa;
step 6: starting a temperature raising program, raising the temperature to 2000 ℃ within 5 hours, and maintaining the temperature for 1 hour;
step 7: and taking out the seed crystal after the temperature is reduced to the room temperature, and obtaining a seed crystal finished product which is uniformly bonded.
The bonding and fixing method does not introduce an adhesive, uses a polycrystalline silicon carbide ceramic block, and has almost no difference of thermal expansion coefficients with silicon carbide seed crystals at high temperature; compared with the traditional adhesive bonding, the adhesive has higher bonding strength and less risk of increasing seed crystal stress caused by the difference of thermal expansion coefficients at high temperature.
While the invention has been described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and additions may be made without departing from the scope of the invention. Equivalent embodiments of the present invention will be apparent to those skilled in the art having the benefit of the teachings disclosed herein, when considered in the light of the foregoing disclosure, and without departing from the spirit and scope of the invention; meanwhile, any equivalent changes, modifications and evolution of the above embodiments according to the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims (10)

1. The silicon carbide seed crystal bonding and fixing method is characterized by comprising the following steps of:
1) Pretreating the bonding surface of the silicon carbide seed wafer;
2) Pretreating the bonding material;
3) Placing the bonding surface of the silicon carbide seed crystal sheet obtained in the step 1) on the bonding material pretreated in the step 2) to enable the bonding surface and the bonding material to be in close contact;
4) Placing the silicon carbide seed wafer and the bonding material in the step 3) into a reaction furnace, reducing the pressure in the reaction furnace, heating in a protective gas atmosphere, and preserving heat after reaching a preset temperature so as to enable partial silicon carbide sublimation and recrystallization to occur between the silicon carbide seed wafer and the bonding material;
5) And cooling to room temperature along with the furnace, and taking out to obtain the silicon carbide seed crystal which is uniformly bonded.
2. The method for bonding and fixing silicon carbide seed crystals according to claim 1, wherein in the step 1), the pretreatment is polishing, and the bonding surface is a silicon surface.
3. The method for bonding and fixing silicon carbide seed crystals according to claim 1, wherein in the step 2), the bonding material is a polycrystalline silicon carbide ceramic block, and the pretreatment is polishing.
4. The method for bonding and fixing silicon carbide seed crystals as set forth in claim 1, wherein in the step 4), the pressure in the reaction furnace is reduced by first evacuating the pressure in the reaction furnace to less than 10 -3 Pa, and then introducing protective gas to maintain the pressure in the reaction furnace at 50-500Pa.
5. The method for bonding and fixing silicon carbide seed crystals according to claim 1, wherein in the step 4), the preset temperature is 1700-2000 ℃, and the heat preservation time is 1-3h.
6. The method for bonding and fixing silicon carbide seed crystals according to claim 1, wherein the area of the bonding material is larger than or equal to the area of the silicon carbide seed wafer.
7. The method for bonding and fixing silicon carbide seed crystals according to claim 1, wherein in the step 4), the shielding gas is argon or helium.
8. The method of claim 1, wherein in step 3), the center of the silicon carbide seed wafer and the center of the bonding material are aligned.
9. A silicon carbide seed crystal bonding and fixing method according to claim 1 or 2, wherein the requirements of the bonding surface of the silicon carbide seed crystal sheet are as follows: the curvature is less than or equal to 30 mu m, the warping degree is less than or equal to 40 mu m, and the roughness is less than or equal to 0.2nm.
10. A silicon carbide seed crystal fixing structure, characterized in that the silicon carbide fixing structure is produced according to the fixing method according to any one of claims 1 to 9.
CN202310202623.6A 2023-03-06 2023-03-06 Silicon carbide seed crystal bonding and fixing method and structure Pending CN116219538A (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20090078516A (en) * 2008-01-15 2009-07-20 (주)크리스밴드 Seed attachment methed for large diameter high quality sic singlecrystal growth
CN104233458A (en) * 2014-09-30 2014-12-24 中国科学院上海硅酸盐研究所 Graphite seed crystal support for silicon carbide crystal growth
CN110306239A (en) * 2019-07-16 2019-10-08 中国科学院上海硅酸盐研究所 A kind of silicon carbide material seed crystal support
KR20200051373A (en) * 2018-11-05 2020-05-13 주식회사 엘지화학 SiC SEED CRYSTAL SUPPORT MEMBER AND MANUFACTURING METHOD THEREOF
CN113550002A (en) * 2021-09-18 2021-10-26 浙江大学杭州国际科创中心 Method and structure for fixing silicon carbide seed crystal
CN215668287U (en) * 2021-09-18 2022-01-28 浙江大学杭州国际科创中心 Fixed knot of carborundum seed crystal constructs

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20090078516A (en) * 2008-01-15 2009-07-20 (주)크리스밴드 Seed attachment methed for large diameter high quality sic singlecrystal growth
CN104233458A (en) * 2014-09-30 2014-12-24 中国科学院上海硅酸盐研究所 Graphite seed crystal support for silicon carbide crystal growth
KR20200051373A (en) * 2018-11-05 2020-05-13 주식회사 엘지화학 SiC SEED CRYSTAL SUPPORT MEMBER AND MANUFACTURING METHOD THEREOF
CN110306239A (en) * 2019-07-16 2019-10-08 中国科学院上海硅酸盐研究所 A kind of silicon carbide material seed crystal support
CN113550002A (en) * 2021-09-18 2021-10-26 浙江大学杭州国际科创中心 Method and structure for fixing silicon carbide seed crystal
CN215668287U (en) * 2021-09-18 2022-01-28 浙江大学杭州国际科创中心 Fixed knot of carborundum seed crystal constructs

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