阅读说明：本技术 碳化硅单晶生长用坩埚结构和碳化硅单晶的生长方法 (Crucible structure for growing silicon carbide single crystal and method for growing silicon carbide single crystal ) 是由 雍庆 娄艳芳 刘春俊 王光明 姚静 张宁 彭同华 杨建� 于 2021-09-17 设计创作，主要内容包括：本发明公开一种碳化硅单晶生长用坩埚结构和碳化硅单晶的生长方法,坩埚结构包括坩埚主体,设有碳化硅原料腔体和顶部开口；封闭所述顶部开口的坩埚盖,所述坩埚盖底部设置有籽晶；至少布置在碳化硅原料腔体的目标原料位以下的石墨过滤结构,所述石墨过滤结构上开设有多层通气孔,且相邻的两层所述通气孔在竖直方向上错位布置。这样一来,在碳化硅单晶生长过程中,碳化硅原料升华形成的气流会经过石墨过滤结构向上进行输运,在气流向上输运的过程中,气流中的碳颗粒等杂质会因石墨过滤结构的阻挡而过滤掉,而气流可以穿过通气孔,传输不会受到影响,从而阻止碳颗粒等杂质进入碳化硅单晶生长界面而形成包裹物,能够有效减少碳化硅单晶中的包裹物。(The invention discloses a crucible structure for growing silicon carbide single crystals and a method for growing the silicon carbide single crystals, wherein the crucible structure comprises a crucible main body, a crucible bottom plate and a crucible bottom plate, wherein the crucible main body is provided with a silicon carbide raw material cavity and a top opening; the crucible cover is used for closing the top opening, and seed crystals are arranged at the bottom of the crucible cover; the graphite filtering structure is at least arranged below a target raw material level of the silicon carbide raw material cavity, multiple layers of vent holes are formed in the graphite filtering structure, and two adjacent layers of vent holes are arranged in a staggered mode in the vertical direction. So, at the silicon carbide single crystal growth in-process, the air current that the silicon carbide raw materials sublimation formed can upwards transport through graphite filtration, upwards transport the in-process at the air current, impurity such as carbon particle in the air current can filter because of graphite filtration's blockking, and the air current can pass the air vent, and the transmission can not receive the influence to prevent impurity such as carbon particle to get into silicon carbide single crystal growth interface and form the parcel, can effectively reduce the parcel in the silicon carbide single crystal.)

1. A crucible structure for growing a silicon carbide single crystal, comprising:

the crucible comprises a crucible main body (1) provided with a silicon carbide raw material cavity and a top opening;

the crucible cover (4) is used for closing the top opening, and seed crystals (3) are arranged at the bottom of the crucible cover (4);

the graphite filtering structure is at least arranged below a target raw material position (5) of the silicon carbide raw material cavity, multiple layers of vent holes are formed in the graphite filtering structure, and the adjacent two layers of vent holes are arranged in a staggered mode in the vertical direction.

2. The crucible structure of claim 1, wherein the filter structure comprises:

arrange many graphite filter tubes (2) below target raw material level (5), graphite filter tube (2) are for having the hollow tube of lumen and a plurality of buckling, graphite filter tube (2) have arranged a plurality of air vents along length direction, just the air vent is including the confession gas entering the inlet port and the air feed body discharge of lumen the venthole of lumen is adjacent in vertical direction the inlet port with the venthole staggered arrangement in vertical direction.

3. Crucible structure in accordance with claim 2, characterized in that the graphite filter tube (2) is a spiral tube bent in a spiral.

4. The crucible structure as recited in claim 3, wherein the axes of the spiral pipes are in a vertical direction, the spiral turns of two adjacent spiral pipes have a partial overlap in the vertical direction, and the number of the spiral pipes is 1-10.

5. The crucible structure of claim 4, wherein the number of turns of the spiral tube is 1-10, the inner diameter is 10-50mm, the thickness of the tube wall is 1-10mm, and the outer diameter of the spiral coil is 10-100 mm;

the top end of the spiral pipe is 0-5mm lower than the target raw material level (5);

the aperture of the vent hole is 5 mu m-5 mm;

the density of the vent holes along the length direction of the spiral pipe is 1-10/cm.

6. Crucible structure in accordance with claim 2, characterized in that the surface of the graphite filter tube (2) is provided with a carbide coating of a refractory metal, the thickness of which is 1-20 μm.

7. The crucible structure of claim 2, wherein the graphite filter structure further comprises:

the graphite filter sheet is arranged on at least one layer above the target raw material level (5), and a plurality of vent holes are formed in the graphite filter sheet.

8. A method for growing a silicon carbide single crystal, characterized in that the silicon carbide single crystal is grown by physical vapor transport using the crucible structure as defined in any one of claims 1 to 7.

9. The growth method according to claim 8, wherein the physical vapor transport method specifically comprises:

the temperature of the seed crystal (3) arranged at the bottom of the crucible cover (4) is set between 2100 and 2300 ℃, the temperature of the silicon carbide raw material in the silicon carbide raw material cavity is set between 2300 and 2500 ℃, and the silicon carbide single crystal is grown under the pressure of 1000-3000 Pa.

Technical Field

The invention relates to the technical field of silicon carbide single crystal growth, in particular to a crucible structure for silicon carbide single crystal growth and a silicon carbide single crystal growth method.

Background

Inclusions are a major defect in single crystals of silicon carbide, and their presence has a great influence on the performance of the device and the yield in mass production. In the process of growing the silicon carbide single crystal by a physical vapor transport method, on one hand, because various impurities exist in the silicon carbide raw material, the impurities can be sublimated into a vapor phase along with the raw material at high temperature, and are gathered on the growth surface of the seed crystal and in the crystal to form a wrapping object of impurity particles; on the other hand, due to the low melting point characteristic of the silicon component, the silicon component can be preferentially evaporated and sublimated, the preferential evaporation and sublimation characteristic of the silicon can cause the silicon carbide raw material to be gradually loosened and carbonized, and the air flow can bring the carbon particles into the growth surface of the seed crystal during the further growth process of the silicon carbide, so that a carbon inclusion is formed in the silicon carbide single crystal.

In summary, how to reduce the inclusions in the silicon carbide single crystal is a technical problem to be solved by those skilled in the art.

Disclosure of Invention

In view of the above, the present invention is directed to a crucible structure for growing a silicon carbide single crystal, which can reduce inclusions in the silicon carbide single crystal.

Another object of the present invention is to disclose a method for growing a silicon carbide single crystal to reduce inclusions in the silicon carbide single crystal.

In order to achieve the purpose, the invention discloses the following technical scheme:

a crucible structure for growing a silicon carbide single crystal, comprising:

the crucible comprises a crucible main body, a crucible cover and a crucible cover, wherein the crucible main body is provided with a silicon carbide raw material cavity and a top opening;

the crucible cover is used for closing the top opening, and seed crystals are arranged at the bottom of the crucible cover;

the graphite filtering structure is at least arranged below a target raw material level of the silicon carbide raw material cavity, multiple layers of vent holes are formed in the graphite filtering structure, and two adjacent layers of vent holes are arranged in a staggered mode in the vertical direction.

Preferably, in the crucible structure, the filter structure includes:

the graphite filter pipes are hollow pipes with pipe cavities and a plurality of bends, a plurality of vent holes are arranged in the graphite filter pipes along the length direction, each vent hole comprises an air inlet hole for allowing air to enter the pipe cavity and an air outlet hole for allowing the air to be discharged from the pipe cavity, and the air inlet holes and the air outlet holes which are adjacent in the vertical direction are arranged in a staggered manner in the vertical direction.

Preferably, in the crucible structure, the graphite filter tube is a spiral tube that is spirally bent.

Preferably, in the crucible structure, the axis of each spiral tube is in the vertical direction, the spiral turns of two adjacent spiral tubes are partially overlapped in the vertical direction, and the number of the spiral tubes is 1-10.

Preferably, in the crucible structure, the number of turns of the spiral pipe is 1-10, the inner diameter is 10-50mm, the thickness of the pipe wall is 1-10mm, and the outer diameter of the spiral ring is 10-100 mm;

the top end of the spiral pipe is 0-5mm lower than the target raw material level;

the aperture of the vent hole is 5 mu m-5 mm;

the density of the vent holes along the length direction of the spiral pipe is 1-10/cm.

Preferably, in the crucible structure, a carbide coating layer of refractory metal is disposed on the surface of the graphite filter tube, and the thickness of the carbide coating layer is 1-20 μm.

Preferably, in the crucible structure, the graphite filter structure further includes:

the graphite filter is arranged above the target raw material position, and a plurality of vent holes are formed in the graphite filter.

According to the technical scheme, in the crucible structure for growing the silicon carbide single crystal, the graphite filter structure at least arranged below the target raw material level of the silicon carbide raw material cavity is arranged in the silicon carbide raw material cavity of the crucible main body, the graphite filter structure is provided with a plurality of layers of vent holes, and two adjacent layers of vent holes are arranged in a staggered mode in the vertical direction; so, at the silicon carbide single crystal growth in-process, the air current that the silicon carbide raw materials sublimation formed can upwards transport through graphite filtration, upwards transport the in-process at the air current, impurity such as carbon particle in the air current can filter because of graphite filtration's blockking, and the air current can pass the air vent, and the transmission can not receive the influence to prevent impurity such as carbon particle to get into silicon carbide single crystal growth interface and form the parcel, can effectively reduce the parcel in the silicon carbide single crystal.

The invention also discloses a growth method of the silicon carbide single crystal, which adopts any one of the crucible structures to grow the silicon carbide single crystal by a physical vapor transport method.

Preferably, in the above growth method, the physical vapor transport method specifically includes:

and setting the temperature of the seed crystal arranged on the inner side of the crucible cover between 2100 and 2300 ℃, setting the temperature of the silicon carbide raw material in the silicon carbide raw material cavity between 2300 and 2500 ℃, and growing under the pressure of 1000-3000 Pa to obtain the silicon carbide single crystal.

According to the technical scheme, the silicon carbide single crystal is grown by adopting the crucible structure through a physical vapor transport method, the graphite filter structure at least arranged below the target raw material level of the silicon carbide raw material cavity is arranged in the silicon carbide raw material cavity of the crucible main body, the graphite filter structure is provided with a plurality of layers of vent holes, and two adjacent layers of vent holes are arranged in a staggered manner in the vertical direction; in the growth process of the silicon carbide single crystal, the airflow formed by sublimation of the silicon carbide raw material can be upwards transported through the graphite filtering structure, impurities such as carbon particles in the airflow can be filtered out due to blocking of the graphite filtering structure in the process of upwards transporting the airflow, the airflow can penetrate through the air vent, and transmission cannot be affected, so that the impurities such as the carbon particles are prevented from entering a growth interface of the silicon carbide single crystal to form a wrapping object, and the wrapping object in the silicon carbide single crystal can be effectively reduced.

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 introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic structural view of a crucible structure for growing a silicon carbide single crystal according to an embodiment of the present invention;

FIG. 2 is a micrograph image of a SiC single crystal grown using a crucible structure without a graphite filter tube as disclosed in an embodiment of the present invention;

FIG. 3 is a microscopic morphology image of a SiC single crystal grown using a crucible structure equipped with a graphite filter tube without a coating according to an embodiment of the present invention;

FIG. 4 is a micrograph image of a SiC single crystal grown using a crucible structure equipped with a graphite filter tube having a refractory metal carbide coating as disclosed in an embodiment of the invention.

Detailed Description

The embodiment of the invention discloses a crucible structure for growing silicon carbide single crystals, which reduces inclusions in the silicon carbide single crystals.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, embodiments of the present invention. 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.

Referring to fig. 1, the crucible structure for silicon carbide single crystal growth disclosed in the embodiment of the present invention includes a crucible main body 1, which is provided with a silicon carbide raw material cavity and a top opening; a crucible cover 4 for sealing the top opening, wherein the bottom of the crucible cover 4 is provided with a seed crystal 3; the graphite filtering structure is at least arranged below a target raw material position 5 of the silicon carbide raw material cavity, multiple layers of vent holes are formed in the graphite filtering structure, and two adjacent layers of vent holes are arranged in a staggered mode in the vertical direction.

Specifically, the crucible cover 4 is screwed to the crucible main body 1 by a screw connection.

In the crucible structure for growing silicon carbide single crystals disclosed in this embodiment, a graphite filter structure arranged at least below a target raw material level 5 of a silicon carbide raw material cavity is arranged in a silicon carbide raw material cavity of a crucible main body 1, a plurality of layers of vent holes are formed in the graphite filter structure, and two adjacent layers of vent holes are arranged in a staggered manner in the vertical direction; so, at the silicon carbide single crystal growth in-process, the air current that the silicon carbide raw materials sublimation formed can upwards transport through graphite filtration, upwards transport the in-process at the air current, impurity such as carbon particle in the air current can filter because of graphite filtration's blockking, and the air current can pass the air vent, and the transmission can not receive the influence to prevent impurity such as carbon particle to get into silicon carbide single crystal growth interface and form the parcel, can effectively reduce the parcel in the silicon carbide single crystal.

Preferably, the filtering structure comprises a plurality of graphite filtering pipes 2 arranged below the target raw material level 5, the graphite filtering pipes 2 are hollow pipes with pipe cavities and a plurality of bends, a plurality of vent holes are arranged in the graphite filtering pipes 2 along the length direction, each vent hole comprises an air inlet hole for allowing air to enter the pipe cavity and an air outlet hole for allowing the air to be discharged from the pipe cavity, and the adjacent air inlet holes and the adjacent air outlet holes in the vertical direction are arranged in a staggered manner in the vertical direction.

In the embodiment, a plurality of bent graphite filter pipes 2 are utilized to form a bent blocking part, so that part of impurities such as carbon particles can be blocked in the process of upward conveying of airflow; and the air vent of dislocation arrangement on the graphite filter tube 2 blocks impurity such as carbon particle through the air vent on the one hand, and on the other hand, blocks impurity such as carbon particle through the mode of dislocation to the filter effect has been improved. And an airflow channel for airflow to pass through can be formed between the graphite filter pipes 2, so that the filtered airflow is convenient to transport.

Alternatively, the graphite filter tube 2 may be replaced with other structures capable of filtering impurities and ensuring normal flow of air flow, such as multiple filter plates arranged at intervals up and down, and vent holes between two adjacent filter plates are arranged along a vertical direction in a staggered manner, and the invention is not described herein any more.

Further, graphite filter tube 2 is the spiral pipe that is the heliciform bending, and the area that the pipeline of spiral pipe runs through is great this moment, can reach better filter effect. It will be appreciated that the graphite filter tube 2 may also have other shapes, such as a serpentine shape, etc.

For convenience of layout, the axes of the spiral pipes are in the vertical direction, as shown in fig. 1, the spiral pipes are arranged on the bottom surface of the crucible main body 1 in the vertical direction, and the spiral coils of two adjacent spiral pipes are partially overlapped in the vertical direction, so that a better filtering effect can be achieved. It will be appreciated that the axis of the spiral pipe may be arranged in other directions, such as horizontally, and the arrangement of the spiral pipe may be layered up and down, so that the spiral pipe is fitted over the entire cross section of the crucible body 1.

Specifically, the number of coils is 1-10, preferably 3-9, and more preferably 5-7.

The number of turns of the spiral tube is 1-10, the number of turns is 1-10, the preferable number of turns is 3-8, and the more preferable number of turns is 4-7;

the inner diameter of the spiral pipe is 10-50mm, preferably 12-45mm, more preferably 15-35 mm; the thickness of the pipe wall is 1-10mm, preferably the thickness is 2-8mm, and more preferably the thickness is 3-6 mm.

The coil has an outer diameter of 10mm to 100mm, preferably a diameter of 20 mm to 80mm, and more preferably a diameter of 30 mm to 60 mm.

The top end of the spiral pipe is 0-5mm lower than the target raw material level 5, the extension length is smaller, the growth cavity space is larger, and the filtering effect can be ensured. Of course, the top end of the spiral pipe can be 0-10mm or 0-8mm lower than the target raw material level 5.

The aperture of the vent hole is 5 μm-5mm, preferably 10 μm-2mm, more preferably 15 μm-1 mm;

the density of the holes of the vent holes along the length direction of the spiral pipe is 1-10/cm, preferably 2-8/cm, and more preferably 4-6/cm.

Of course, other values of the above parameters can be adopted according to the specification and production requirements of the crucible body 1, and the invention is not limited thereto.

In order to further optimize the technical scheme, a carbide coating of refractory metal is arranged on the surface of the graphite filter pipe 2, and the refractory metal is a rare metal. Generally referred to as tungsten, molybdenum, niobium, tantalum, vanadium, zirconium, and may also include rhenium and hafnium. The metal has the characteristics of high melting point, high hardness and strong corrosion resistance, and most of the metal can generate compounds with high melting point, high hardness and good chemical stability with carbon, nitrogen, silicon, boron and the like.

The graphite filter tube 2 is coated with a refractory metal carbide coating which has stable chemical properties and cannot be corroded by air flow, so that new impurities cannot be introduced in the growth process of the silicon carbide single crystal.

Specifically, the thickness of the carbide coating is 1 to 20 μm. Preferably between 3 and 15 μm thick, more preferably between 5 and 10 μm thick.

In a further technical scheme, the graphite filter structure further comprises: at least one layer of graphite filter sheet arranged above the target raw material level 5, wherein a plurality of vent holes are formed in the graphite filter sheet. According to the invention, on the basis that the plurality of graphite filter pipes 2 are arranged below the target raw material level 5, at least one layer of graphite filter sheet above the target raw material level 5 is combined, so that double filtration of airflow formed by sublimation of the silicon carbide raw material is realized, impurities in the raw material can be filtered to a greater extent, the Si/C ratio in the growth process of the silicon carbide crystal is adjusted, and carbon inclusions in the silicon carbide crystal are further reduced.

It can be understood that, in order to save cost and facilitate operation, the present invention may not provide a filtering structure above the target raw material level 5 on the premise that the plurality of graphite filtering tubes 2 provided below the target raw material level 5 achieve the filtering effect.

The embodiment of the invention also discloses a growth method of the silicon carbide single crystal, which adopts the crucible structure provided by any one of the embodiments to grow the silicon carbide single crystal by a physical vapor transport method.

According to the growth method of the silicon carbide single crystal disclosed by the embodiment of the invention, the crucible structure disclosed by the embodiment of the invention is adopted to grow the silicon carbide single crystal by a physical vapor transport method, a graphite filtering structure at least arranged below a target raw material position 5 of a silicon carbide raw material cavity is arranged in a silicon carbide raw material cavity of a crucible main body 1, a plurality of layers of vent holes are formed in the graphite filtering structure, and two adjacent layers of vent holes are arranged in a staggered manner in the vertical direction; in the growth process of the silicon carbide single crystal, the airflow formed by sublimation of the silicon carbide raw material can be upwards transported through the graphite filtering structure, impurities such as carbon particles in the airflow can be filtered out due to blocking of the graphite filtering structure in the process of upwards transporting the airflow, the airflow can penetrate through the air vent, and transmission cannot be affected, so that the impurities such as the carbon particles are prevented from entering a growth interface of the silicon carbide single crystal to form a wrapping object, and the wrapping object in the silicon carbide single crystal can be effectively reduced.

Preferably, the physical vapor transport method specifically includes: the temperature of the seed crystal 3 arranged on the inner side of the crucible cover 4 is set between 2100 and 2300 ℃, the temperature of the silicon carbide raw material in the silicon carbide raw material cavity is set between 2300 and 2500 ℃, and the silicon carbide single crystal is grown under the pressure of 1000-3000 Pa.

The invention adopts a growth method of the silicon carbide single crystal, the temperature of the seed crystal 3 is set between 2100 and 2300 ℃, the temperature of the silicon carbide raw material is set between 2300 and 2500 ℃, and the comparative test of growing the silicon carbide single crystal under the pressure of 1000Pa-3000Pa is as follows:

example 1

When the crucible cover is used, the lower surface of the crucible cover 4 is used for adhering the seed crystal 3, enough SiC powder raw material is filled at the bottom of the crucible structure, then the crucible cover 4 adhered with the seed crystal 3 is arranged at the upper part of the crucible main body 1, and the crucible cover is put into a single crystal growth furnace after being assembled. The grown crystal was processed, and the wafer was observed under a microscope, and as a result, it was found that the single crystal contained a large amount of inclusions, as shown in FIG. 2.

Example 2

When the crucible cover is used, the lower surface of the crucible cover 4 is used for adhering the seed crystal 3, enough SiC powder raw material and 5 graphite accessories of spiral tubes without coatings are arranged at the bottom of the crucible structure, then the crucible cover 4 adhered with the seed crystal 3 is arranged at the upper part of the crucible main body 1, and the crucible cover is put into a single crystal growth furnace after being assembled. The grown crystal was processed and the wafer was observed under a microscope, and as a result, it was found that the single crystal contained less inclusions, as shown in FIG. 3.

Example 3

When the crucible cover is used, the lower surface of the crucible cover 4 is used for adhering the seed crystal 3, enough SiC powder raw material and 5 graphite accessories of spiral pipes with refractory metal carbide coatings are arranged at the bottom of the crucible structure, then the crucible cover 4 adhered with the seed crystal 3 is placed on the upper part of the crucible main body 1, and the crucible cover is placed in a single crystal growth furnace after being assembled. The grown crystal was processed and the wafer was observed under a microscope, and as a result, it was seen that the single crystal was substantially free of inclusions, as shown in fig. 4.

It can be seen from the comparison of the data that the spiral tube provided by the embodiment has the graphite accessory with the refractory metal carbide coating, and the carbon inclusion in the SiC single crystal can be effectively reduced.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.