CN212451745U - Quick expanding growth system for silicon carbide single crystal - Google Patents
Quick expanding growth system for silicon carbide single crystal Download PDFInfo
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- CN212451745U CN212451745U CN202021415249.6U CN202021415249U CN212451745U CN 212451745 U CN212451745 U CN 212451745U CN 202021415249 U CN202021415249 U CN 202021415249U CN 212451745 U CN212451745 U CN 212451745U
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Abstract
The utility model discloses a quick hole enlargement growth system of carborundum single crystal relates to semiconductor crystal growth technical field for solve among the prior art under the prerequisite of guaranteeing the crystal quality, can't realize the problem of the quick hole enlargement of carborundum single crystal betterly. The utility model provides a quick hole enlargement growth system of carborundum single crystal, include: a crucible barrel having a metal or metal compound coating; the crucible cover is arranged at the top end of the crucible barrel, and the crucible barrel is provided with a metal or metal compound coating; a baffle disposed inside the crucible barrel, the baffle having a metal or metal compound coating; the guide plate is used for dividing the inside of the crucible barrel into two areas with different volumes, and the part of the guide plate, which is positioned in the growth cavity, is provided with a bend angle for adjusting the flow direction of the components.
Description
Technical Field
The utility model relates to a semiconductor crystal growth technical field especially relates to a quick hole enlargement growth system of carborundum single crystal.
Background
Silicon carbide (SiC) material is a wide bandgap semiconductor material with excellent physical and electrical properties. The forbidden band width is 3.5eV, and the silicon has the electric breakdown field intensity which is 10 times that of silicon and the thermal conductivity which is 3 times that of silicon. The outstanding performances enable the silicon carbide single crystal material to have wide application prospects in the fields of high-power, high-temperature and high-frequency devices. With the deep development of silicon materials, silicon-based devices are approaching the performance limit of silicon materials, and only silicon carbide semiconductor materials with stronger intrinsic characteristics are sought for further improving the device performance. Silicon carbide devices are orders of magnitude lower in power loss than silicon devices, both in the on-state condition and during switching, which will greatly improve the conversion efficiency of electrical energy. With the emergence of emerging industries, photovoltaic inversion, new energy vehicles, rapid charging piles, smart grid management, industrial automation and new generation high power communication are included, and higher requirements on energy conservation and electric energy management are provided. The silicon carbide semiconductor device can obviously save energy in the fields, reduce the emission of fossil fuel and reduce environmental pollution.
However, silicon carbide cannot be grown by necking and then expanding rapidly as single crystal silicon is limited by the growth method and preparation technology of the silicon carbide single crystal. The silicon material has a low melting point, can be grown by a pulling single crystal liquid phase method, and is relatively easy to realize rapid diameter expansion by controlling a temperature field. Silicon carbide materials can be melted only by being melted at 3200 ℃ and 10 ten thousand of atmospheric pressure, so that the ordinary industrial production under extreme conditions is difficult to realize. Therefore, silicon carbide single crystals can be produced only by the growth mode of solid-gas-solid conversion, which is a so-called sublimation recrystallization method. To date, the most mature method of growing silicon carbide is the Physical Vapor Transport (PVT) method or the so-called modified Lely method. The silicon carbide powder and the seed crystal are put into a crucible, the seed crystal is placed in an upper low-temperature area, the silicon carbide powder is placed in a bottom high-temperature area, and the silicon carbide single crystal block is grown through sublimation and recrystallization of the powder.
The existing diameter expansion method of the silicon carbide single crystal is that the diameter is expanded by 2-5mm each time by using seed crystals with certain diameter and good crystal quality under the condition of ensuring that the quality of the grown crystals is not deteriorated; and cutting, grinding and polishing the expanded silicon carbide single crystal to obtain a wafer serving as a seed crystal for next diameter expansion. The above process is repeated continuously, however, the good crystal quality of the grown silicon carbide single crystal cannot be ensured in each diameter expansion process, which also increases the difficulty of diameter expansion of the silicon carbide single crystal. In addition, a large radial temperature gradient needs to be maintained during the crystal growth process, so that the internal stress of the crystal is large and the crystal is easy to crack. Through the development of three decades, the diameter of silicon carbide reaches 8 inches, and the diameter is increased, so that the diameter expansion becomes more and more difficult. And the time is longer and longer, and 5-10 years is consumed for every 2 inches of enlargement.
Another method of producing large crystals of silicon carbide is by rapid diameter enlargement by splicing of multiple small seed crystals. For example, patent CN105671638A discloses a method for preparing large diameter SiC seed crystal, which comprises: trimming and cutting the small-diameter SiC seed crystal; and adhering and fixing the seed crystals on the seed crystal support in a close-packed splicing mode to form a first layer of seed crystals, adhering and fixing a second layer of seed crystals above gaps among the small-diameter SiC seed crystals of the first layer of seed crystals, covering the gaps formed by the first layer of seed crystals with the second layer of seed crystals to form double-layer spliced seed crystals, polishing, annealing, promoting lateral growth and preparing the complete large-diameter SiC seed crystals.
Patent CN106435732A discloses a method for rapidly preparing a large-size SiC single crystal ingot, comprising a first stage of processing the shape of a small-size SiC wafer into a required shape, combining, splicing and arranging the processed wafers and fixing the wafers on a graphite seed crystal support; the second stage, the seed crystal support fixed with the small wafer combination is placed in a seed crystal sublimation system, growth conditions suitable for transverse growth of single crystals are selected, and gaps among the small wafers are filled with the transversely grown single crystals to form complete large-size SiC seed crystals; and in the third stage, the large-size seed crystals obtained in the second stage are used for carrying out the growth by a seed crystal sublimation method, and finally large-size silicon carbide monocrystalline ingots are obtained, and the monocrystalline ingots are subjected to shape processing to finally obtain large-size SiC crystal bars.
Patent CN110541199A discloses a method for preparing high quality SiC seed crystal with diameter of 8 inches and above, comprising: cutting, splicing, grinding and polishing a small-size SiC wafer or SiC crystal, and then carrying out homoepitaxial growth; the homoepitaxial growth is carried out in two stages: (1) And (3) lateral extension: carrying out lateral epitaxial growth at the splicing gap of the circular spliced SiC seed crystals to fill the splicing gap, (2) carrying out surface epitaxy: after the filling of the splicing gap is finished, the growth conditions are changed, the growth rate of the (0001) surface of the seed crystal is promoted, the defect density of the growth surface of the seed crystal is greatly reduced, the crystallization quality of the growth surface of the seed crystal is improved, and the high-quality SiC seed crystal with the size of 8 inches or more, which has small surface total thickness change, no crack and less defect density, is obtained.
It can be seen that the methods disclosed above all use a plurality of single crystal seeds to increase the diameter of the crystal by splicing, but no matter the method uses longitudinal filling or transverse growth to fill the splicing gaps between the wafers, the method cannot completely achieve complete butt joint on the crystal lattice, and therefore grain boundaries are formed in the splicing regions. Moreover, the strict definition of crystallography on single crystals is not satisfied when the single crystals are grown by using polycrystalline seed crystals; therefore, the bulk material grown by splicing multiple seed crystals can only be called polycrystal, but can not be called monocrystal.
Therefore, how to rapidly increase the diameter of the silicon carbide single crystal on the premise of ensuring the crystallization quality is still a technical problem that needs to be solved by those skilled in the art.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a quick hole enlargement growth system of carborundum single crystal and method for solve among the prior art under the prerequisite of guaranteeing the crystal quality, can't realize the technical problem of the quick hole enlargement of carborundum single crystal betterly.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
a system for rapid diameter expansion growth of a silicon carbide single crystal, comprising: a crucible barrel having a metal or metal compound coating; the crucible cover is arranged at the top end of the crucible barrel, and the crucible barrel is provided with a metal or metal compound coating; a baffle disposed inside the crucible barrel, the baffle having a metal or metal compound coating; the guide plate is used for dividing the inside of the crucible barrel into two areas with different volumes, and the part of the guide plate, which is positioned in the growth cavity, is provided with a bend angle for adjusting the flow direction of the components.
One surface of the crucible cover, which is adhered with the seed crystal, is covered by a high-temperature refractory metal or metal compound coating, and the coating is made of tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide.
The inner side of the crucible barrel is covered by a high-temperature refractory metal or metal compound coating, and the coating is made of tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide.
The guide plate is covered by a high-temperature refractory metal or metal compound coating, and the coating is made of tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide.
Specifically, one side of the crucible cover, which is adhered to the seed crystal, is provided with a groove.
Furthermore, the roughness of the inner surface of the groove is 1-10 mu m.
Specifically, a clamping groove is formed in the crucible barrel and used for fixing the guide plate.
Specifically, the flow guide plate divides the interior of the crucible barrel into two areas with different volumes, and the charge amount of the outer side of the flow guide plate accounts for 1/3-2/5 of the total amount.
In practical application, the system for rapidly expanding the diameter of the silicon carbide single crystal further comprises: a high temperature furnace chamber; the crucible consisting of the crucible barrel and the crucible cover is arranged in the high-temperature furnace chamber.
Wherein, the outside of crucible is equipped with induction heating coil.
A method for rapidly expanding and growing a silicon carbide single crystal comprises the following steps: cutting a 2-8 inch positive direction silicon carbide single crystal block, and then grinding and chemically and mechanically polishing the upper surface, the lower surface and the circumferential surface of the wafer to form a positive direction silicon carbide wafer with a certain thickness; then cleaning and packaging the processed wafer for later use;
sticking the positive silicon carbide wafer prepared in the above step as a seed crystal into a recess of a crucible cover having a metal or metal compound coating layer so that the circumferential surface portion of the silicon carbide wafer is exposed to the outside;
fixing the flow guide plate with the coating in a graphite crucible barrel with the coating on the inner surface; a clamping groove is formed in the crucible barrel, a guide plate is arranged in the clamping groove for fixing, the guide plate divides the powder into two areas with different volumes, and a bending angle for adjusting the flow direction of the components is arranged on the part of the guide plate, which is positioned in the growth cavity; the guide plate not only plays a role in separating silicon carbide powder, but also plays a role in adjusting the direction of component flow;
high-purity silicon carbide powder is filled into a crucible barrel with a coating, wherein the crucible barrel is clamped with the guide plate, and the height of the silicon carbide powder is flush with the lower edge of the lower bent angle part of the guide plate; covering the crucible cover fixed with the seed crystal on a crucible barrel filled with high-purity silicon carbide powder to assemble a silicon carbide single crystal growth system;
putting the assembled crucible into a high-temperature furnace chamber, sealing the heating furnace chamber, vacuumizing the heating furnace chamber, and preheating the heating furnace chamber;
carrying out etching pretreatment on the seed crystal; introducing an etching chemical gas into the chamber of the heating furnace, continuously heating and raising the temperature, and preserving the temperature for a period of time to finish the etching pretreatment process of the exposed surface of the seed crystal;
stopping introducing the etching gas, and introducing inert gas instead; and continuously raising the heating temperature, keeping the temperature for a period of time to finish the expanding growth of the silicon carbide single crystal, stopping introducing the inert gas after the growth is finished, stopping heating, cooling to room temperature, and taking out the grown silicon carbide single crystal.
Wherein the orientation of the forward silicon carbide wafer is a forward [0001], and the error allowance range is +/-0.25 degrees; the thickness of the forward silicon carbide wafer is more than 3 mm.
One surface of the crucible cover, which is adhered with the seed crystal, is covered by a high-temperature refractory metal or metal compound coating, and the coating is made of tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide.
Specifically, the roughness of the inner surface of a groove for sticking the seed crystal to the crucible cover is 1-10 mu m, and the depth of the groove is smaller than the thickness of the seed crystal; the seed crystal is tightly adhered to the crucible cover, and no gap cavity is left in the middle.
Wherein the baffles are covered by a high temperature refractory metal or metal compound coating; the crucible barrel is covered by a high-temperature refractory metal or metal compound coating.
Specifically, the charging amount of the outer side of the guide plate accounts for 1/3-2/5 of the total amount.
Wherein the vacuum degree of the chamber of the heating furnace is 1.0 multiplied by 10-4～5.0×10-4Pa; the preheating temperature of the heating furnace cavity is 1300-1550 ℃, and the preheating time is 24-48 h; the purpose of preheating is to discharge moisture and impurity gases adsorbed on the furnace and crucible walls.
Wherein the etching chemical gas is hydrogen, hydrogen chloride, silicon tetrachloride or silicon tetrafluoride.
Specifically, the etching temperature is 1700-1800 ℃, and the heat preservation time is 5-50 min; the etching effect cannot be achieved when the temperature is too low, and the seed crystal is damaged when the temperature is too high.
Wherein the flow rate of the inert gas is 5-600 sccm, and the growth pressure is 2000-8000 Pa; the temperature is increased to 2150-2550 ℃ as the growth temperature, and the heat preservation growth time is 80-240H.
Compared with the prior art, the system and the method for rapidly expanding and growing the silicon carbide single crystal have the following advantages:
the utility model provides a quick expanding growth system of carborundum single crystal and method, adopt the physical vapor phase transmission method, combine the crystallography, thermodynamics, the dynamics principle and the crystallization nucleation control principle that carborundum single crystal grows, through adopting the carborundum single crystal material that has certain thickness as the seed crystal, and polish the processing through curved surface chemical mechanical polishing technique with its periphery and be used for the side direction expanding growth, put into (growth component) guide plate in crystal growth chamber and carborundum powder material, be used for controlling carborundum single crystal and preferentially carry out the expanding growth, carry out axial growth again; the surface layer and the internal structure material of the growth cavity are coated by adopting a metal or alloy compound material with high temperature resistance, corrosion resistance and low radiation coefficient, and the most important key point is that the coating material can inhibit the nucleation growth of silicon carbide on the surface thereof and effectively inhibit the formation of polycrystal; by the coating method, the phenomenon that the diameter expansion of the silicon carbide single crystal is stopped due to parasitic polycrystal generated in the diameter expansion process can be effectively avoided. Through the utility model provides a quick diameter-expanding growth method of silicon carbide single crystal, can realize the quick diameter-expanding of silicon carbide single crystal, only can realize through single diameter-expanding growth that the diameter of silicon carbide single crystal increases 10-20mm to can guarantee that the whole crystallization quality of silicon carbide single crystal keeps good after the diameter-expanding; in addition, the silicon carbide single crystal material after rapid diameter expansion can greatly increase the effective utilization area of the silicon carbide substrate, and has obvious gain effect on the cost control of the silicon carbide-based electronic device.
Drawings
FIG. 1 is a schematic flow chart of a method for rapid diameter-expanding growth of a silicon carbide single crystal according to an embodiment of the present invention;
FIG. 2 is a schematic structural view of an apparatus for diameter-expanding growth of a silicon carbide single crystal according to a first comparative example;
FIG. 3 is a schematic structural diagram of a first system for rapid diameter expansion growth of a silicon carbide single crystal according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a second system for rapid diameter expansion growth of a silicon carbide single crystal according to an embodiment of the present invention.
Reference numerals:
1-crucible cover; 2-crucible barrel; 3-high purity silicon carbide powder; 4-induction heating coil; 51 a-forward silicon carbide seed crystal; 51 b-an axially grown silicon carbide single crystal; 52 a-a forward silicon carbide seed crystal having a thickness and a circumferential surface which has been polished; 52 b-a portion of the single crystal of silicon carbide grown radially expanded, 52 c-a portion of the single crystal of silicon carbide grown axially expanded; 62-a baffle.
Detailed Description
For the convenience of understanding, the system and the method for rapid diameter expansion growth of silicon carbide single crystal provided by the embodiments of the present invention are described in detail below with reference to the accompanying drawings.
A system for rapid diameter expansion growth of a silicon carbide single crystal, as shown in fig. 3 and 4, comprising: a crucible barrel 2, the crucible barrel 2 having a metal or metal compound coating; the crucible cover 1 is arranged at the top end of the crucible barrel 2, and the crucible barrel 2 is provided with a metal or metal compound coating; a baffle plate 62, wherein the baffle plate 62 is arranged inside the crucible barrel 2, and the baffle plate 62 is coated with metal or metal compound; the baffle plate 62 is used to divide the inside of the crucible barrel 2 into two regions of different volumes, and the portion of the baffle plate 62 located in the growth chamber has a bend angle for adjusting the flow direction of the components.
Wherein, one surface of the crucible cover 1, which is adhered with the seed crystal, is covered by a high-temperature refractory metal or metal compound coating, and the coating material can be tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide.
The inner side of the crucible barrel 2 is covered by a high-temperature refractory metal or metal compound coating, and the coating material can be tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide.
The above-mentioned baffle plate 62 is covered by a high-temperature refractory metal or metal compound coating, and the coating material may be tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide.
Specifically, the side of the crucible cover 1 to which the seed crystal is attached may have a groove having a depth smaller than the thickness of the seed crystal so that the circumferential surface portion of the silicon carbide wafer is exposed to the outside.
Further, the roughness of the inner surface of the groove can be 1-10 μm.
Specifically, the crucible barrel 2 may be provided with a locking groove therein, and the locking groove may be used to fix the guide plate 62.
Specifically, the flow guide plate 62 can divide the interior of the crucible barrel 2 into two areas with different volumes, and the charge amount outside the flow guide plate 62 can account for 1/3-2/5 of the total amount.
In practical application, the system for rapidly expanding the diameter of the silicon carbide single crystal according to the embodiment of the present invention may further include: a high temperature furnace chamber so that the crucible consisting of the crucible barrel 2 and the crucible cover 1 can be placed therein.
Wherein, an induction heating coil 4 may be provided on the outer side of the crucible composed of the crucible barrel 2 and the crucible cover 1, as shown in fig. 3 and 4.
The embodiment of the utility model provides a quick hole enlargement growth method of carborundum single crystal, including following step:
step S1, cutting the 2-8 inch positive direction silicon carbide single crystal block, and then grinding and chemically and mechanically polishing the upper and lower surfaces and the circumferential surface of the wafer to process the positive direction silicon carbide wafer with a certain thickness; then cleaning and packaging the processed wafer for later use;
step S2, sticking the positive silicon carbide wafer prepared in the above step as a seed crystal into the groove of the crucible cover with a metal or metal compound coating, so that the circumferential surface part of the silicon carbide wafer is exposed to the outside;
step S3, fixing the guide plate with the coating into a graphite crucible barrel with the coating on the inner surface; a clamping groove is formed in the crucible barrel, a guide plate is arranged in the clamping groove for fixing, the guide plate divides the powder into two areas with different volumes, and a bending angle for adjusting the flow direction of the components is arranged on the part of the guide plate, which is positioned in the growth cavity; the guide plate not only plays a role in separating silicon carbide powder, but also plays a role in adjusting the direction of component flow;
step S4, high-purity silicon carbide powder is filled into a crucible barrel with a coating, and a guide plate is clamped well, so that the height of the silicon carbide powder is flush with the lower edge of the lower corner part of the guide plate; covering the crucible cover fixed with the seed crystal on a crucible barrel filled with high-purity silicon carbide powder to assemble a silicon carbide single crystal growth system;
step S5, placing the assembled crucible into a high-temperature furnace chamber, sealing the heating furnace chamber, vacuumizing the heating furnace chamber, and preheating the heating furnace chamber;
step S6, carrying out etching pretreatment on the seed crystal; introducing an etching chemical gas into the chamber of the heating furnace, continuously heating and raising the temperature, and preserving the temperature for a period of time to finish the etching pretreatment process of the exposed surface of the seed crystal;
step S7, stopping introducing the etching gas, and introducing inert gas instead; and continuously raising the heating temperature, keeping the temperature for a period of time to finish the expanding growth of the silicon carbide single crystal, stopping introducing the inert gas after the growth is finished, stopping heating, cooling to room temperature, and taking out the grown silicon carbide single crystal.
Compared with the prior art, the system and the method for rapidly expanding and growing the silicon carbide single crystal have the following advantages:
the embodiment of the utility model provides an among silicon carbide single crystal growth system and method that expands diameter fast, adopt the physical vapor phase transmission method, combine the crystallography, thermodynamics, the dynamics principle and the crystallization nucleation control principle that silicon carbide single crystal grows, through adopting the silicon carbide single crystal material that has certain thickness as the seed crystal, and polish the processing through curved surface chemical mechanical polishing technique with its periphery and be used for the growth of expanding diameter of side direction, imbed (growth component) guide plate in crystal growth chamber and silicon carbide powder material, be used for controlling silicon carbide single crystal and preferentially carry out the growth of expanding diameter, axial growth again; the surface layer and the internal structure material of the growth cavity are coated by adopting a metal or alloy compound material with high temperature resistance, corrosion resistance and low radiation coefficient, and the most important key point is that the coating material can inhibit the nucleation growth of silicon carbide on the surface thereof and effectively inhibit the formation of polycrystal; by the coating method, the phenomenon that the diameter expansion of the silicon carbide single crystal is stopped due to parasitic polycrystal generated in the diameter expansion process can be effectively avoided. Through the utility model provides a quick diameter-expanding growth method of silicon carbide single crystal, can realize the quick diameter-expanding of silicon carbide single crystal, only can realize through single diameter-expanding growth that the diameter of silicon carbide single crystal increases 10-20mm to can guarantee that the whole crystallization quality of silicon carbide single crystal keeps good after the diameter-expanding; in addition, the silicon carbide single crystal material after rapid diameter expansion can greatly increase the effective utilization area of the silicon carbide substrate, and has obvious gain effect on the cost control of the silicon carbide-based electronic device.
It should be added here that the rapid diameter expansion growth according to the present invention means that the diameter of the single crystal is increased by 10mm or more, even by 15mm or more, and even by 20mm or more after the single diameter expansion growth of the silicon carbide single crystal while ensuring that the crystal quality of the silicon carbide single crystal is not deteriorated.
Wherein, the orientation of the positive silicon carbide wafer is positive [0001], that is, the positive silicon carbide single crystal is the silicon carbide single crystal of which the normal line of the surface is crystallographically [0001], and the error allowable range can be +/-0.25 degrees; also, the thickness of the forward silicon carbide wafer may be greater than 3 mm.
One surface of the crucible cover, which is adhered with the seed crystal, is covered by a high-temperature refractory metal or metal compound coating, and the coating material can be tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide.
Specifically, the roughness of the inner surface of the groove for sticking the seed crystal on the crucible cover can be 1-10 μm, and the depth of the groove is less than the thickness of the seed crystal; and the seed crystal is tightly adhered to the crucible cover, and no gap cavity is left between the seed crystal and the crucible cover.
Wherein, the guide plate is covered by a high-temperature refractory metal or metal compound coating, and the coating material can be tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide; accordingly, the crucible barrel is covered by a high-temperature refractory metal or metal compound coating, and the coating material can be tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide.
Specifically, the charging amount of the outer side of the guide plate can be 1/3-2/5 in total. The high-purity silicon carbide powder is a silicon carbide powder having a purity of 99.99% or more.
Wherein the heating furnace chamberThe vacuum degree of the chamber may be 1.0X 10-4～5.0×10-4Pa; the preheating temperature of the heating furnace cavity can be 1300-1550 ℃, and the preheating time can be 24-48 h; specifically, the purpose of preheating is to discharge moisture and impurity gases adsorbed on the furnace wall and crucible wall.
The etching chemical gas may be hydrogen, hydrogen chloride, silicon tetrachloride or silicon tetrafluoride. For example: the etching chemical gas can be hydrogen, and the hydrogen is high-purity hydrogen, and the high-purity hydrogen refers to hydrogen with the purity of more than 99.999%. The inert gas may be argon gas, and the argon gas may be high-purity argon gas having a purity of 99.999% or more.
Specifically, the etching temperature can be 1700-1800 ℃, and the heat preservation time can be 5-50 min; further, the etching effect cannot be achieved due to too low temperature, and the seed crystal is damaged due to too high temperature.
Wherein, the flow rate of the inert gas can be 5-600 sccm, and the growth pressure can be 2000-8000 Pa; the rising temperature can be 2150-2550 ℃, and the rising temperature is used as the growth temperature, and the heat preservation growth time can be 80-240H.
The embodiment of the utility model provides a quick hole enlargement growth method of carborundum single crystal mainly has following several advantages:
the diameter of the silicon carbide single crystal can be rapidly increased, and the expansion of 6 inches to 8 inches and the expansion of 8 inches to 10 inches can be rapidly realized; by arranging the guide plate in the growth cavity, the transport direction of the growth components can be effectively adjusted, and the silicon carbide single crystal preferentially grows along the radial direction; the high-temperature coating is added on the inner surface of the crucible, so that the generation of polycrystal at the edge of the seed crystal can be effectively inhibited, and the growth crystallization quality of the crystal is ensured while the diameter expansion growth is ensured; the transverse growth of the crystal can block the generation of threading dislocation, so that the integral crystal quality is improved;
secondly, the internal stress of the silicon carbide single crystal in the growth process can be effectively reduced, cracking caused by overlarge internal stress in subsequent processing is avoided, and the yield of products is improved; in the process of crystal growth, the diameter expansion of the crystal is controlled by controlling the flow direction of component flow and inhibiting the generation of polycrystal through a high-temperature resistant coating; the method of the utility model is obviously superior to the existing method, the diameter expansion of the crystal is realized by controlling the large radial temperature gradient, and the large radial temperature gradient can cause the generation of serious internal stress and defects;
the service lives of the crucible and the internal guide plate can be effectively prolonged; after the inner wall surface of the crucible and the surface of the guide plate are subjected to coating treatment, the coating has high-temperature corrosion resistance, so that the crucible and internal components can be repeatedly used for many times, the use times of the crucible are greatly increased, the service life of the crucible is prolonged, and the comprehensive use cost is greatly reduced;
fourthly, the prepared expanded diameter silicon carbide single crystal has obvious gain effect on the cost control of the silicon carbide-based electronic device; with the increase of the diameter of the silicon carbide single crystal, the effective utilization area of the silicon carbide substrate for preparing the device is increased in a quadratic relation, so that the unit cost of the silicon carbide-based electronic device can be quickly reduced, and the popularization and application process of the silicon carbide semiconductor device is accelerated.
The first embodiment is as follows:
a method for rapid diameter-expanding growth of silicon carbide single crystals comprises the following steps:
step S1, cutting the 6-inch positive direction silicon carbide single crystal block, then grinding and chemically and mechanically polishing the upper surface, the lower surface and the circumferential surface of the wafer to enable the roughness of the surface to be less than 1nm, processing the wafer into silicon carbide seed crystals with the thickness of 4mm, and then cleaning and packaging the surface of the wafer for later use;
step S2, sticking the positive silicon carbide wafer prepared in the step S1 as a seed crystal into a groove of a crucible cover with a tantalum carbide coating, wherein the depth of the groove is 1mm, and the surface roughness of the seed crystal stuck to the groove is 5 mu m, so that a part of the circumferential surface of the silicon carbide seed crystal is exposed outside to ensure that no gap or bubble exists between the seed crystal and the crucible cover;
step S3, fixing the guide plate with the tantalum carbide coating into the graphite crucible barrel with the inner surface coated; a clamping groove is formed in the crucible barrel, a guide plate is arranged in the clamping groove and fixed, the guide plate divides the powder into two areas with different volumes, and the part of the guide plate, which is positioned in the growth cavity, is used for adjusting the direction bend angle of the component flow; the guide plate not only plays a role in separating the silicon carbide powder, but also plays a role in adjusting the direction of component flow;
step S4, high-purity silicon carbide powder is filled into a crucible barrel with a tantalum carbide coating and clamped with a guide plate, so that the height of the silicon carbide powder is flush with the lower edge of the lower corner part of the guide plate; the charge between the deflector and the crucible wall accounted for 40% of the total charge; and the crucible cover with the seed crystal fixed in the step S2 is buckled on the crucible barrel filled with the high-purity silicon carbide powder to assemble the silicon carbide single crystal growth system as shown in the figure 3;
step S5, putting the assembled graphite crucible into a vertical heating furnace, sealing the furnace chamber, vacuumizing the chamber of the heating furnace to make the vacuum degree reach 2.0 multiplied by 10-4Pa, heating to 1500-1550 ℃ in a heating way, controlling the heating rate at 20 ℃/min, and discharging water and impurity gas adsorbed on the inner wall of the crucible;
step S6, introducing high-purity hydrogen of an etching gas, controlling the flow rate at 150sscm and the pressure at 50000Pa, continuously heating to 1750 ℃, and preserving the temperature for 20min to finish the etching pretreatment process of the surface of the silicon carbide seed crystal;
s7, stopping introducing high-purity hydrogen, introducing high-purity argon instead, controlling the flow at 100sscm and the pressure at 2000Pa, continuously heating to 2300 ℃, controlling the heating rate at 5 ℃/min, and preserving the heat for 150 hours to finish the diameter expansion growth of the silicon carbide single crystal; and after the growth is finished, stopping introducing the argon, stopping heating, cooling to room temperature, controlling the cooling rate at 15 ℃/min, and taking out the silicon carbide single crystal obtained by expanding growth.
The silicon carbide single crystal prepared by the first embodiment has no obvious defect proliferation, the diameter of the single crystal area is increased from the original 150mm to 164mm, and the increase of 14mm is realized by single diameter expansion.
Example two:
a method for rapid diameter-expanding growth of silicon carbide single crystals comprises the following steps:
step S1, cutting the 6-inch positive direction silicon carbide single crystal block, then grinding and chemically and mechanically polishing the upper surface, the lower surface and the circumferential surface of the wafer to enable the roughness of the surface to be less than 1nm, processing the wafer into silicon carbide seed crystals with the thickness of 4mm, and then cleaning and packaging the surface of the wafer for later use;
step S2, sticking the positive silicon carbide wafer prepared in the step S1 as a seed crystal into a groove of a crucible cover with a tantalum carbide coating, wherein the depth of the groove is 1mm, and the surface roughness of the seed crystal stuck to the groove is 5 mu m, so that a part of the circumferential surface of the silicon carbide seed crystal is exposed outside to ensure that no gap or bubble exists between the seed crystal and the crucible cover;
step S3, fixing the guide plate with the tantalum carbide coating into the graphite crucible barrel with the inner surface coated; a clamping groove is formed in the crucible barrel, a guide plate is arranged in the clamping groove and fixed, the guide plate divides the powder into two areas with different volumes, and the part of the guide plate, which is positioned in the growth cavity, is used for adjusting the direction bend angle of the component flow; the guide plate not only plays a role in separating the silicon carbide powder, but also plays a role in adjusting the direction of component flow;
step S4, high-purity silicon carbide powder is filled into a crucible barrel with a tantalum carbide coating and clamped with a guide plate, so that the height of the silicon carbide powder is flush with the lower edge of the lower corner part of the guide plate; the charge between the deflector and the crucible wall accounted for 40% of the total charge; and the crucible cover with the seed crystal fixed in the step S2 is buckled on the crucible barrel filled with the high-purity silicon carbide powder to assemble the silicon carbide single crystal growth system as shown in the figure 4;
step S5, putting the assembled graphite crucible into a vertical heating furnace, sealing the furnace chamber, vacuumizing the chamber of the heating furnace to make the vacuum degree reach 2.0 multiplied by 10-4Pa, heating to 1500-1550 ℃ in a heating way, controlling the heating rate at 20 ℃/min, and discharging water and impurity gas adsorbed on the inner wall of the crucible;
step S6, introducing high-purity hydrogen of an etching gas, controlling the flow rate at 150sscm and the pressure at 50000Pa, continuously heating to 1750 ℃, and preserving the temperature for 20min to finish the etching pretreatment process of the surface of the silicon carbide seed crystal;
s7, stopping introducing high-purity hydrogen, introducing high-purity argon instead, controlling the flow at 100sscm and the pressure at 2000Pa, continuously heating to 2300 ℃, controlling the heating rate at 5 ℃/min, and preserving the heat for 150 hours to finish the diameter expansion growth of the silicon carbide single crystal; and after the growth is finished, stopping introducing the argon, stopping heating, cooling to room temperature, controlling the cooling rate at 15 ℃/min, and taking out the silicon carbide single crystal obtained by expanding growth.
The silicon carbide single crystal prepared by the second embodiment has no obvious defect proliferation, the diameter of the single crystal area is increased to 170mm from the original 150mm, and the increase of 20mm is realized by single diameter expansion.
Comparative example one:
the preparation method is the same as the first embodiment, but the difference is that in step S3, no (growth component) guide plate loaded in the growth chamber and the powder is used, and the whole assembly is as shown in FIG. 2.
The diameter of the silicon carbide single crystal area prepared by the first comparative example is increased from 150mm to 153mm, and the diameter is increased by only 3 mm.
Comparative example two:
the preparation method is the same as the first embodiment except that the crucible cover and the crucible barrel are not subjected to high-temperature coating treatment in steps S2 and S3, and the growth chamber and the (growth component) guide plate in the powder are not loaded in step S3.
In the case of polycrystalline formation of a large area at the edge of the silicon carbide single crystal prepared in the second comparative example, the diameter of the silicon carbide single crystal region was reduced from 150mm to 145mm, whereas the diameter of the single crystal region was reduced by 5 mm.
The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. A system for rapidly expanding and growing a silicon carbide single crystal is characterized by comprising:
a crucible barrel having a metal or metal compound coating;
the crucible cover is arranged at the top end of the crucible barrel, and the crucible barrel is provided with a metal or metal compound coating;
a baffle disposed inside the crucible barrel, the baffle having a metal or metal compound coating; the guide plate is used for dividing the inside of the crucible barrel into two areas with different volumes, and the part of the guide plate, which is positioned in the growth cavity, is provided with a bend angle for adjusting the flow direction of the components.
2. The system for rapidly expanding and growing the silicon carbide single crystal according to claim 1, wherein one surface of the crucible cover, which is adhered with the seed crystal, is covered by a high-temperature refractory metal or metal compound coating, and the coating is made of tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide.
3. The system for rapid diameter expansion growth of silicon carbide single crystal according to claim 1, wherein the inside of the crucible barrel is covered by a high temperature refractory metal or metal compound coating, and the coating material is tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide.
4. The system for rapidly expanding and growing the silicon carbide single crystal according to claim 1, wherein the flow guide plate is covered by a high-temperature refractory metal or metal compound coating, and the coating is made of tantalum, tantalum carbide, hafnium carbide, niobium or niobium carbide.
5. The system for rapidly expanding the diameter of the silicon carbide single crystal according to claim 1 or 2, wherein the side of the crucible cover, to which the seed crystal is attached, is provided with a groove.
6. A system for rapid diameter expansion growth of a silicon carbide single crystal according to claim 5, wherein the roughness of the inner surface of the groove is 1 to 10 μm.
7. The system for rapidly expanding the diameter of the silicon carbide single crystal according to claim 1 or 3, wherein a clamping groove is formed in the crucible barrel, and the clamping groove is used for fixing the guide plate.
8. The system for rapid diameter expansion growth of a silicon carbide single crystal according to claim 1 or 4, wherein the baffle plate divides the inside of the crucible barrel into two regions of different volumes, and the amount of charge on the outside of the baffle plate accounts for 1/3 to 2/5 of the total amount.
9. A system for rapid diameter expansion growth of a silicon carbide single crystal according to claim 1, further comprising: a high temperature furnace chamber; the crucible consisting of the crucible barrel and the crucible cover is arranged in the high-temperature furnace chamber.
10. A system for rapid diameter expansion growth of a silicon carbide single crystal according to claim 9, wherein an induction heating coil is provided outside the crucible.
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