CN-121992483-A - Liquid phase method silicon carbide single crystal growth system and growth method

CN121992483ACN 121992483 ACN121992483 ACN 121992483ACN-121992483-A

Abstract

The invention discloses a liquid phase method silicon carbide single crystal growth system and a growth method, comprising a furnace body, a heat preservation barrel, a crucible, a heating element, a liftable seed rod, a radar level gauge and a radar level gauge, wherein the heat preservation barrel is positioned in the furnace body, the crucible is positioned in the heat preservation barrel, the heating element is positioned in the furnace body and surrounds the heat preservation barrel, the liftable seed rod penetrates out of the furnace body, the lower end of the liftable seed rod is connected with a seed plate and can extend into the crucible, and a microwave signal sent by the radar level gauge can reach the liquid level of a melt in the crucible. The growth system can stably work for a long time under the protection of high temperature, vacuum or inert gas, and can realize high-precision and real-time monitoring of the liquid level height in the growth period of the liquid phase method silicon carbide single crystal with the length of 60-80 hours. By providing reliable liquid level height data for the growth control system, the position stability of a solid-liquid interface can be effectively maintained, and adverse effects of temperature gradient fluctuation on the growth rate and morphology of crystals are avoided, so that the growth controllability, the crystal quality and the yield of the liquid phase method silicon carbide single crystals are improved.

Inventors

LI CHEN
LU YUANHAO
LI HAOCHAO
DONG LEI
KE SHANMING
TANG SHUXIAN

Assignees

粤港澳大湾区(广东)量子科学中心

Dates

Publication Date: 20260508
Application Date: 20260225

Claims (10)

1. A liquid phase method silicon carbide single crystal growth system, characterized in that the liquid phase method silicon carbide single crystal growth system comprises: A furnace body; The heat preservation barrel is positioned in the furnace body; The crucible is positioned in the heat-preserving barrel; The heating body is positioned in the furnace body and surrounds the heat-preserving barrel; the upper end of the liftable seed rod penetrates out of the furnace body, and the lower end of the liftable seed rod is connected with the seed crystal disc and can extend into the crucible; The radar liquid level gauge is positioned at the top of the furnace body, and a microwave signal sent by the radar liquid level gauge can reach the liquid level of the molten liquid in the crucible.
2. The liquid phase method silicon carbide single crystal growth system according to claim 1, further comprising an insulating layer, wherein the insulating layer is positioned in the furnace body and sleeved outside the heating body and the insulating barrel; The radar liquid level gauge is aligned with the liquid level of the melt in the crucible through transparent windows positioned on the furnace body, the heat preservation layer and the heat preservation barrel, the transparent windows are made of sapphire or quartz, and the thickness of the transparent windows is 5-10 mm.
3. The liquid phase method silicon carbide single crystal growth system according to claim 2, wherein the crucible is a graphite crucible, the heating element is a graphite heating element, and the heat-insulating layer is a graphite heat-insulating felt; the radar liquid level gauge is arranged at the top of the furnace body through a wave guide cylinder or a wave guide; The liquid phase method silicon carbide single crystal growth system further comprises: the CCD camera is used for monitoring an image of the contact of the seed crystal and the melt; and the infrared temperature sensor is used for monitoring the temperature distribution near the crucible in real time.
4. A liquid phase method silicon carbide single crystal growth system according to any of claims 1-3 and wherein said liquid phase method silicon carbide single crystal growth system further comprises: The seed rod lifting mechanism is connected with the upper end of the seed rod and used for driving the seed rod to ascend or descend; The seed rod weight sensor and the seed rod position sensor are positioned on the seed rod and are respectively used for measuring the total mass of the seed rod, the seed plate and the seed crystal and the end face position of the seed crystal in real time; the crucible weight sensor is positioned at the lower part of the crucible and is used for measuring the total mass of the crucible and the molten liquid in the crucible in real time; the upper computer is connected with the radar liquid level meter, the seed rod weight sensor and the crucible weight sensor, and is used for judging whether seed crystals are in contact with the liquid level of the melt or not according to measurement data of the radar liquid level meter, the seed rod weight sensor and the crucible weight sensor, calculating the lifting speed of the seed rods and sending instructions to the PLC execution unit; The PLC execution unit is connected with the upper computer and the seed rod lifting mechanism respectively and is used for controlling the lifting and descending of the seed rod or changing the lifting speed of the seed rod according to instructions issued by the upper computer.
5. The liquid phase method silicon carbide single crystal growth system according to claim 4, wherein the host computer is embedded with the following calculation formulas (1) to (3); the upper computer is obtained by a calculation formula (1) And send out the descending seed rod to the PLC execution unit Instructions of (2); The upper computer is obtained through a calculation formula (2) and a calculation formula (3) And And according to And (3) with All are equal to a preset positive value, the contact of the seed crystal and the liquid level of the melt is judged, and an instruction for lifting the seed rod to carry out the growth of the silicon carbide single crystal is sent to the PLC execution unit, and according to the following conditions And (3) with All are equal to 0, judging that the seed crystal is not contacted with the liquid level of the melt, and sending an instruction for descending the seed crystal rod to the PLC execution unit; (1) (2) (3) Wherein, the The initial height of the seed crystal end face is set; the initial height of the liquid level of the melt; the initial height difference between the end face of the seed crystal and the liquid level of the melt; Is the initial total mass of the crucible and the melt; The initial total mass of the seed rod, the seed crystal disc and the seed crystal; is the seed rod descends Afterwards, the total mass of the crucible and the melt; is the seed rod descends Then, the total mass of the seed rod, the seed crystal disc and the seed crystal; The seed rod is lowered compared with the initial total mass of the crucible and the melt A reduction in total mass of the rear crucible and the melt; To decrease the seed rod compared to the initial total mass of the seed rod, seed plate and seed And adding the total weight of the rear seed rod, the seed crystal plate and the seed crystal.
6. The liquid phase method silicon carbide single crystal growth system according to claim 5, wherein the upper computer calculates a growth thickness of the silicon carbide single crystal based on measurement data of a radar level gauge, a seed rod weight sensor, and a crucible weight sensor, calculates a growth rate of the silicon carbide single crystal based on the growth thickness of the silicon carbide single crystal, and calculates a seed rod pulling rate based on the growth rate of the silicon carbide single crystal.
7. The liquid phase method silicon carbide single crystal growth system according to claim 6, wherein the upper computer is embedded with a calculation formula (4) and a calculation formula (5) as follows, the growth thickness of the silicon carbide single crystal is obtained by the calculation formula (4), and the growth rate of the silicon carbide single crystal is obtained by the calculation formula (5); (4) (5) Wherein, the To be at intervals of time A growth thickness of the inner silicon carbide single crystal; To be at intervals of time Apparent weight gain of the internal seed crystal, namely weight gain measured by a seed rod weight sensor; is the cross section area of the end face of the seed crystal; Is the density of the melt; Is silicon carbide single crystal density; To be at intervals of time The liquid level of the inner melt drops; is the growth rate of the silicon carbide single crystal.
8. The liquid phase method silicon carbide single crystal growth system according to claim 7, wherein the upper computer is embedded with the following calculation formula (6) and calculation formula (7), and the seed rod pulling speed is obtained through the calculation formula (6) and the calculation formula (7); (7) Wherein, the Actual deviation of the interface; the height of the end face of the seed crystal at the moment t; the liquid level of the melt at the moment t; the pulling speed of the seed rod is set; Is the growth rate of the silicon carbide single crystal; Is a proportionality coefficient; Is an integral coefficient; Is a differential coefficient; for a preset desired distance between the seed crystal end face and the melt level, the values of Δ 0 at the different growth stages are as follows: During the meniscus control phase 0< Delta 0 <2mm, during the steady state growth phase, -2mm < Delta 0 <0.
9. A method for growing a liquid-phase process silicon carbide single crystal based on the liquid-phase process silicon carbide single crystal growth system according to any one of claims 1 to 3, comprising the steps of: Melting silicon and a metal cosolvent in the crucible by utilizing a heating element to form a melt; And lowering the seed rod to make the seed crystal contact with the liquid level of the melt, then pulling the seed rod to grow the silicon carbide single crystal, and monitoring the height of the liquid level of the melt in the crucible in real time through a radar level gauge in the process of growing the silicon carbide single crystal.
10. A method for growing a liquid-phase silicon carbide single crystal based on the liquid-phase silicon carbide single crystal growing system according to any one of claims 4 to 8, comprising the steps of: Melting silicon and a metal cosolvent in the crucible by utilizing a heating element to form a melt; starting a radar liquid level meter, a crucible weight sensor and a seed rod weight sensor, and judging whether the seed crystal is in contact with the liquid level of the melt or not by an upper computer according to measurement data of the radar liquid level meter, the seed rod weight sensor and the crucible weight sensor before silicon carbide single crystal grows; When the seed crystal is contacted with the liquid level of the melt, the seed rod is pulled to grow the silicon carbide single crystal, and in the growth process of the silicon carbide single crystal, the upper computer obtains the growth rate of the silicon carbide single crystal according to the measurement data of the radar liquid level meter, the seed rod weight sensor and the crucible weight sensor, and the growth rate of the silicon carbide single crystal is the seed rod pulling rate, and sends a command to the PLC execution unit; and the PLC execution unit controls the rising and falling of the seed rod or changes the lifting speed of the seed rod according to the instruction issued by the upper computer, so that the growth of the silicon carbide single crystal is realized.

Description

Liquid phase method silicon carbide single crystal growth system and growth method Technical Field The invention relates to the technical field of crystal growth, in particular to a liquid phase method silicon carbide single crystal growth system and a liquid phase method silicon carbide single crystal growth method. Background Silicon carbide (SiC) is used as a third-generation semiconductor material, and has wide application prospect in the fields of new energy automobiles, smart grids, high-speed railways, advanced radars and the like due to high thermal conductivity, high breakdown field strength and excellent high-temperature high-power performance. The dislocation density of the silicon carbide single crystal grown by the liquid phase method can be remarkably reduced, high-quality silicon carbide can be obtained, and the defect of high dislocation density in the traditional gas phase method is overcome, so that the liquid phase method growth technology becomes a research hot spot in recent years. In the process of growing a silicon carbide single crystal by a liquid phase method, silicon and a flux element are put into a high purity graphite crucible and heated to a molten state, and a temperature gradient is formed in the axial direction of the high Wen Rongye by controlling a temperature field. When the temperature field is stable and the concentration of carbon in the high-temperature melt reaches balance, pushing down the seed crystal and contacting with the high-temperature melt, and epitaxially separating out silicon carbide monocrystal on the surface of the seed crystal. The growth cycle of liquid phase process silicon carbide single crystals is typically as long as about 60-80 hours, and during such long growth, as silicon and carbon are continuously consumed, a large amount of carbon dissolution occurs at the wall of the graphite crucible, and the melt level in the graphite crucible continuously drops, resulting in a change in the growth solid-liquid interface conditions. For example, a decrease in liquid level may change the temperature gradient at the solid-liquid interface, affecting supersaturation precipitation of carbon, thereby significantly reducing the driving force for crystal growth. If the temperature gradient of the solid-liquid interface is abnormally fluctuated, the crystal growth rate can lose stability, and when the temperature gradient is overlarge, the quality problems of rough crystal surface, inclusion formation, polycrystallization, grain boundary defects and the like are easily caused. In addition, if the seed crystal accidentally breaks away from the liquid level of the melt due to the falling of the liquid level in the growth process, the crystal growth is interrupted, and even an unstable crystal structure is formed on the surface of the seed crystal, so that the problems of crystal polytype transformation and the like are caused. Therefore, if the liquid level cannot be monitored timely and accurately, the solid-liquid interface frequently fluctuates, the crystal growth stability is remarkably reduced, and even single crystals cannot grow stably for a long time. The high quality growth of liquid phase silicon carbide single crystals depends on stable control of the solid-liquid interface position over a long period of time, so the liquid level is a key factor affecting the interface stability. Accordingly, the prior art is still in need of improvement and development. Disclosure of Invention Based on the defects in the prior art, the invention aims to provide a liquid phase method silicon carbide single crystal growth system and a liquid phase method silicon carbide single crystal growth method, and aims to realize timely and accurate detection of the liquid level. The technical scheme of the invention is as follows: in a first aspect of the present invention, there is provided a liquid phase method silicon carbide single crystal growth system, wherein the liquid phase method silicon carbide single crystal growth system comprises: A furnace body; The heat preservation barrel is positioned in the furnace body; The crucible is positioned in the heat-preserving barrel; The heating body is positioned in the furnace body and surrounds the heat-preserving barrel; the upper end of the liftable seed rod penetrates out of the furnace body, and the lower end of the liftable seed rod is connected with the seed crystal disc and can extend into the crucible; The radar liquid level gauge is positioned at the top of the furnace body, and a microwave signal sent by the radar liquid level gauge can reach the liquid level of the molten liquid in the crucible. Optionally, the liquid phase method silicon carbide single crystal growth system further comprises an insulation layer, wherein the insulation layer is positioned in the furnace body and sleeved outside the heating body and the insulation barrel; The radar liquid level gauge is aligned with the liquid level of the melt in the cr