CN102644105B - A kind of method of PVT method grow silicon carbide crystals and device thereof - Google Patents
A kind of method of PVT method grow silicon carbide crystals and device thereof Download PDFInfo
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Abstract
The present invention relates to a kind of method and device thereof of PVT method grow silicon carbide crystals, removable adiabatic regulatory element is set above crucible, during grow silicon carbide crystals, along with the crystal on crucible cover is long thick, progressively increase the distance D between removable adiabatic regulatory element and crucible cover; Wherein, increase with crystal thickness, crystal is to the thermal resistance R of hot-fluid Q
cto increase; Removable adiabatic regulatory element is to the equivalent thermal resistance R of hot-fluid Q
bincrease with distance D is reduced, by keeping R
cincrease and R
bthe mutual running balance of decrease, ensure that crystallization interface temperature remains unchanged.Thermal insulation element above crucible cover is modified to and can moves according to processing requirement in crystal growing process by the present invention, by change and plumbago crucible lid between distance, thus change heat-insulation system geometry, change plumbago crucible energy output and reach the object regulating the warm field in plumbago crucible in the process of crystal growth.
Description
Technical field
The present invention relates to a kind of method and device thereof of PVT method grow silicon carbide crystals.
Background technology
Silicon carbide (SiC) monocrystalline has that high thermal conductivity, high-breakdown-voltage, carrier mobility are high, the very high excellent semiconductor physics of chemical stability; The high frequency, high power electronic device and the opto-electronic device that work under high temperature, intense radiation conditions can be made into, there is huge using value in national defence, high-tech, industrial production, power supply, field of power transformation, be counted as the third generation semiconductor material with wide forbidden band having development prospect.But, grow silicon carbide crystals is very difficult, through making great efforts for many years, the laboratory being representative with Gree company of the U.S. now is successfully used physical gas phase deposition technology (PVT) to grow large diameter high quality single-crystal silicon carbide and make epitaxial substrate and is sold in the international market, succeeded in developing electron device and the opto-electronic device of multiple excellent property with single-crystal silicon carbide epitaxial substrate.
At present, physical gas phase deposition technology is the normally used method of grow silicon carbide crystals, as shown in Figure 1.In the airtight plumbago crucible 1 of a particular design, bottom is equipped with a certain amount of silicon carbide polycrystal powder (particle) and is expected 2, be spaced a distance above it, single-crystal silicon carbide sheet as seed crystal 3 be pasted onto crucible on cover, the periphery of plumbago crucible 1 and bottom enclose the heat-insulation system 4 that certain thickness carbon (graphite) felt or foamy carbon (polity's carbon felt) are made.The top of crucible also has the suitable upper thermal insulation element 5 of the thickness of thermometer hole 6 by processing requirement center of settling, and makes to form the warm field being applicable to growing silicon carbice crystals in crucible.Plumbago crucible 1, be all placed on one with the vacuum chamber 7 of isolated from atmosphere together with the heat-insulation system 4 etc. of surrounding, during growing crystal, vacuum chamber 7 is filled with the high-purity Ar gas of proper air pressure again and makes air pressure remain on the numerical value of technique needs by burner hearth air pressure automatic control system after being extracted into the vacuum tightness of needs.Plumbago crucible 1 is made to reach the high temperature of needs and make temperature remain on the temperature (usually, at 2000 DEG C-2500 DEG C) of technique needs by automatic temperature control system by the induction heating of induction coil 8.Under high temperature, the sic powder in plumbago crucible 1 starts to flash to saturated vapo(u)r, be transported to regelation in the lower seed crystal face of temperature by diffusion and gaseous exchange effect, seed crystal is grown up gradually and forms a large single crystal.
During PVT method grow silicon carbide crystals, the several factors such as the shape of plumbago crucible and structure, load coil, intermediate frequency power supply frequency, heating power, heat-insulation system, burner hearth air pressure all can affect growing silicon carbice crystals process.Wherein, the temperature distribution in the crucible formed by many factors is most important to being formed of crystal growing process and lattice defect, and excessive quantity research is done in lot of domestic and international laboratory on this question, delivers the article of a lot of regarding assay and Computer Numerical Simulation.As document 1:Self-CongruentProcessofSiCGrowthbyPhysicalVaporTranspo rtD.I.Cherednichenko, R.V.Drachev, T.S.Sudarshan, JournalofCrystalGrowth262 (2004) 175-181.It is one of them example.In the process of PVT method grow silicon carbide crystals, the saturated vapor pressure P of vapor phase in crucible
vdepend on the temperature T of evaporation source
v, the condensing vapour pressure P on crystallization interface
mdepend on the temperature T of crystal plane
m, vapour pressure P
vp is pressed with condensing vapour
mthe existence of pressure reduction is the phase transformation impellent that crystal interface is occurred crystallisation process, and its size is conclusive important parameter to crystallisation process.Particularly point out analyze mass transfer in growing silicon carbice crystals process and heat transfer process in detail in article after: along with crystal is grown up, the crystal formation thermal resistance grown up to can cause the temperature in crystal structure face long thick and change with crystal, and variable quantity is quite large and be non-linear.Fig. 2 is the Fig.1 in document 1, the mathematical model used when giving the hot-fluid and temperature distribution problems that are formed in plumbago crucible when grow silicon carbide crystals is discussed.Fig. 3 is the Fig.2 in document 1, the change that the temperature giving crystal growth plane during grow silicon carbide crystals under the processing parameter condition selected author occurs with crystal thickness, Fig. 4 a is the Fig.3a in document 1, Fig. 4 b is the Fig.3b in document 1, and it provides the change that crystalline growth velocity occurs with crystal thickness.Can find out, variable quantity is quite large, greatly to crystal thickness reach a certain amount of after cause process of growth almost to stop.The more important thing is, in whole process of growth, the temperature of crystallization interface, crystallization impellent and crystalline growth velocity are changing always, and the instability of process of growth must cause occurring multiple lattice defect in crystal, is difficult to grow up to high-quality crystal.
Summary of the invention
For prior art Problems existing, the object of the present invention is to provide a kind of method of PVT method grow silicon carbide crystals, the method achieve crystal growth plane in whole process of growth and remain substantially invariable temperature and substantially invariable saturation steam pressure reduction, improve crystal mass significantly.Another object of the present invention is to provide a kind of device implementing aforesaid method.
For achieving the above object, the method of a kind of PVT method of the present invention grow silicon carbide crystals, be specially: removable adiabatic regulatory element is set above crucible, during grow silicon carbide crystals, along with the crystal on crucible cover is long thick, progressively increase the distance D between removable adiabatic regulatory element and crucible cover; Wherein, increase with crystal thickness, crystal is to the thermal resistance R of hot-fluid Q
cto increase; Removable adiabatic regulatory element is to the equivalent thermal resistance R of hot-fluid Q
bincrease with distance D is reduced, by keeping R
cincrease and R
bthe mutual running balance of decrease, ensure that crystallization interface temperature remains unchanged.
A kind of device implementing aforesaid method, comprise vacuum chamber, crucible, heat-insulation system and thermal insulation element, heat-insulation system is enclosed in circumferential part and the bottom of crucible, thermal insulation element is arranged on the top of crucible, crucible, heat-insulation system and thermal insulation element are all arranged in vacuum chamber, the periphery of vacuum chamber is provided with induction coil, wherein, thermal insulation element comprises thermal insulation element and removable adiabatic regulatory element, upper thermal insulation element is fixedly mounted on the top of crucible cover, removable adiabatic regulatory element is movably arranged on the top of thermal insulation element, removable adiabatic regulatory element can be moved up and down by automatic controls movement Systematical control, removable adiabatic regulatory element moves the distance increasing or reduce between crucible cover, produce and constantly become hot-fluid that is large or that diminish, the hot-fluid total amount adjusted in crucible remains unchanged.
Further, the top of described vacuum chamber is provided with tongued and grooved flanges, and its central part is provided with the infrared pyrometer for measuring temperature in described crucible.
Further, the middle part of described upper thermal insulation element and removable adiabatic regulatory element is provided with the thermometer hole suitable with described infrared pyrometer.
Further, described automatic controls movement system comprises vacuum dynamic seal knot, straight-line motion mechanism and automatic control part, automatic control part controls straight-line motion mechanism action according to the temperature variation curve that described infrared pyrometer is measured, and straight-line motion mechanism is tied by vacuum dynamic seal and driven described removable adiabatic regulatory element to carry out upper and lower translational motion.
Further, described vacuum dynamic seal knot comprises union lever and high vacuum corrugated tube, the lower end of union lever is fixedly connected on described removable adiabatic regulatory element, the lower end of high vacuum corrugated tube is sealedly connected on the upper surface of described upper tongued and grooved flanges, and the upper end of high vacuum corrugated tube is sealedly connected on the top of union lever.
Further, described straight-line motion mechanism comprises precise ball line slideway and ball-screw, and the top of described union lever is connected with ball-screw.
Further, described automatic control part comprises driving mechanism and control unit, and control unit accepts the detection signal of described infrared pyrometer, and control and drive system work, driving mechanism is connected with described ball-screw by driving syndeton.
Further, described driving mechanism comprises stepper-motor or AC servo motor, and the output terminal of motor is provided with reduction box.
Further, described automatic controls movement system is arranged on described upper tongued and grooved flanges by erecting frame.
In the present invention, the thermal insulation element above crucible cover is modified to and can moves according to processing requirement in crystal growing process, by change and plumbago crucible lid between distance, thus change heat-insulation system geometry, change plumbago crucible energy output and reach the object regulating the warm field in plumbago crucible in the process of crystal growth.Use this regulation technology, can eliminate well with the change causing warm field in plumbago crucible because crystal length is thick occurred during PVT method grow silicon carbide crystals, the temperature field reached in the plumbago crucible of process of growth remains stablizes constant object.Grow into high quality crystal.
Accompanying drawing explanation
Fig. 1 is SiC Crystal Growth Equipment structural representation in prior art;
Fig. 2 is the accompanying drawing 1 in document 1;
Fig. 3 is the accompanying drawing 2 in document 1;
Fig. 4 a is the accompanying drawing 3a in document 1;
Fig. 4 b is the accompanying drawing 3b in document 1;
Fig. 5 is structural representation of the present invention;
Fig. 6 is principle of the invention structured flowchart.
Embodiment
Below, with reference to accompanying drawing, the present invention is more fully illustrated, shown in the drawings of exemplary embodiment of the present invention.But the present invention can be presented as multiple multi-form, and should not be construed as the exemplary embodiment being confined to describe here.But, these embodiments are provided, thus make the present invention comprehensively with complete, and scope of the present invention is fully conveyed to those of ordinary skill in the art.
For ease of illustrating, here can use such as " on ", the space relative terms such as D score " left side " " right side ", for illustration of the element of shown in figure or the feature relation relative to another element or feature.It should be understood that except the orientation shown in figure, spatial terminology is intended to comprise device different azimuth in use or operation.Such as, if the device in figure is squeezed, be stated as the element being positioned at other elements or feature D score will be positioned at other elements or feature " on ".Therefore, exemplary term D score can comprise upper and lower both orientation.Device can otherwise be located (90-degree rotation or be positioned at other orientation), and space used here illustrates relatively can correspondingly explain.
By the hot-fluid Q=Q of crystal plane when Fig. 2 describes PVT method grow silicon carbide crystals
v+ Q
w+ L, at aufwuchsplate and the back side formation temperature difference T of crystal
c=T
s-T
c.Thermal conduction study provides, Δ T
c=Q*R
c, wherein, R
cit is the thermal resistance of crystal.In addition, hot-fluid also by by the plumbago crucible lid (crystal is bonded on plumbago crucible) after crystal and the upper thermal insulation element that rests on above crucible cover, forms temperature difference T between crucible cover top and bottom
s=Q*R
s, between upper thermal insulation element top and bottom, form temperature difference T
b=Q*R
b; Wherein, R
sthe thermal resistance of crucible cover, R
bit is the thermal resistance of upper thermal insulation element.During growing crystal, the temperature T of aufwuchsplate
m=T
b+ Δ T
s+ Δ T
cin formula, T
bthe temperature at the crucible cover back side, namely as the temperature that the pyrometer of temperature automatic control signal detects, if keep constant in process of growth, the temperature T of aufwuchsplate
m=T
b+ Δ T
s+ Δ T
cby with the Δ T in crystal constantly thickening, formula
cstrengthen and constantly raise.If (reduce heating power, the temperature T of aufwuchsplate
mcan decline, but raw materials evaporate temperature also can be made simultaneously to decline, simultaneously result reduces another growth parameter(s) played a decisive role--the saturation steam pressure reduction between evaporation source and crystal plane.）
In patent of the present invention, the thermal insulation element above crucible cover is divided into two parts, as shown in Figure 5: wherein a part still rests on above crucible; The removable thermal insulation element of the removable adiabatic regulatory element 9(of another part) be then connected with the running gear outside burner hearth by a joining of graphite bar, keep certain distance with crucible cover, be suspended on above crucible cover.At this moment, removable thermal insulation element is to the equivalent thermal resistance R of hot-fluid Q
bexcept depending on geometric shape, size and the thermal properties of itself, also by relevant to the distance D of removable thermal insulation element and plumbago crucible upper surface: equivalent thermal resistance R
bto increase with distance D and reduce (dull but non-linear).Like this, during growing crystal, with crystal thickness increase, thermal resistance R
cwhile strengthening, by running gear strengthening the distance between removable thermal insulation element and plumbago crucible, the equivalent thermal resistance R of upper thermal insulation element will be made
breduce.With the equivalent thermal resistance R of thermal insulation element
breduce, the temperature T at the crucible cover back side
bcorresponding reduction.By automatically controlling the temperature T making crystal plane
m=T
b+ Δ T
s+ Δ T
ct in formula
bdecrement and Δ T
cincrement equal, just can reach the requirement keeping crystal plane temperature-resistant under the condition not changing heating power.By the method for computer simulation, T can be obtained
bdue initial value makes crystal plane temperature T with meeting in process of growth
mremain unchanged required T
bthe accurate theoretical value of due change.Also suitable T can be summed up by simulated experiment
mthe empirical curve of change.During growing crystal, move by program automatic control system the temperature T that removable adiabatic regulatory element 9 makes pyrometer detect
brule on request changes, and just can reach the temperature T of crystal plane
mthe requirement remained unchanged in process of growth.The general-purpose simulation method of calculation of use and software is needed commercially to have bought.
As shown in Figure 5, Figure 6, the method of a kind of PVT method of the present invention grow silicon carbide crystals, be specially: removable adiabatic regulatory element 9 is set above crucible, during grow silicon carbide crystals, along with the crystal on crucible cover is long thick, progressively increase the distance D between removable adiabatic regulatory element 9 and crucible cover; Wherein, increase with crystal thickness, crystal is to the thermal resistance R of hot-fluid Q
cto increase; Removable adiabatic regulatory element is to the equivalent thermal resistance R of hot-fluid Q
bincrease with distance D is reduced, by keeping R
cincrease and R
bthe mutual running balance of decrease, ensure that crystallization interface temperature remains unchanged.
During grow silicon carbide crystals, along with the crystal on crucible cover is long thick, the crystal grown up to can make hot-fluid Q to the heat insulating function that aufwuchsplate produces
0constantly diminish; Increase the distance between removable adiabatic regulatory element 9 and plumbago crucible lid, the heat insulating function of removable adiabatic regulatory element to crucible can be made constantly to reduce, make hot-fluid Q
0' constantly increase.
In process of growth, keep the heating power of input constant, by experiment or numerical simulation calculation, can find and make two to hot-fluid Q
0with Q
0' act on the impact that contrary factor produces cancel out each other, make total hot-fluid Q remain unchanged in whole process of growth (thus, crystallization impellent P
v-P
mand crystallization interface temperature T
mremain unchanged) the temperature variation curve of crucible point for measuring temperature.Use thermal insulation-automatic temperature control system to make the temperature of plumbago crucible thermometric by the curvilinear motion provided, thus make crystal all the time at crystallization impellent P
v-P
mand crystallization interface temperature T
mremain unchanged and (note that crystallization interface temperature T
mnot identical with plumbago crucible point for measuring temperature temperature) ideal conditions under grow, be achieved the great variety causing warm field in plumbago crucible because crystal length is thick occurred when eliminating grow silicon carbide crystals, reach the object improving the overall homogeneity of crystal, reduce lattice defect, grow up to high quality crystal.
A kind of device implementing aforesaid method, comprise vacuum chamber 7, crucible 1, heat-insulation system 4 and thermal insulation element, heat-insulation system 4 is enclosed in circumferential part and the bottom of crucible 1, thermal insulation element is arranged on the top of crucible 1, crucible 1, heat-insulation system 4 and thermal insulation element are all arranged in vacuum chamber 7, and the periphery of vacuum chamber 7 is provided with induction coil 8.The top of vacuum chamber 7 is provided with tongued and grooved flanges 10, and its central part is provided with the infrared pyrometer 11 for measuring temperature in described crucible.Thermal insulation element comprises thermal insulation element 5 and removable adiabatic regulatory element 9, upper thermal insulation element 5 is fixedly mounted on the top of crucible cover, removable adiabatic regulatory element 9 is movably arranged on the top of thermal insulation element 5, and the middle part of upper thermal insulation element 5 and removable adiabatic regulatory element 9 is provided with the thermometer hole 6 suitable with infrared pyrometer 11.Removable adiabatic regulatory element 9 can be moved up and down by automatic controls movement Systematical control, removable adiabatic regulatory element 9 moves the distance between accurate controlling and adjustment itself and crucible cover, produce and constantly become hot-fluid that is large or that diminish, the hot-fluid total amount adjusted in crucible 1 remains unchanged.
Automatic controls movement system comprises vacuum dynamic seal knot, straight-line motion mechanism and automatic control part, and automatic controls movement system is arranged on upper tongued and grooved flanges 10 by erecting frame.The temperature variation curve that automatic control part is measured according to infrared pyrometer 11 controls straight-line motion mechanism action, straight-line motion mechanism is tied by vacuum dynamic seal and is driven removable adiabatic regulatory element 9 in crystal growing process, need to carry out precision, movement at a slow speed by technique, vacuum dynamic seal junction structure guarantees that the Mechanical Moving of union lever can not bring vacuum hearth leakage problem.
Vacuum dynamic seal knot comprises union lever 12 and high vacuum corrugated tube 13, the lower end of union lever 12 is fixedly connected on removable adiabatic regulatory element 9, the lower end of high vacuum corrugated tube 13 is sealedly connected on the upper surface of tongued and grooved flanges 10, and the upper end of high vacuum corrugated tube 13 is sealedly connected on the top of union lever 12.Straight-line motion mechanism comprises precise ball line slideway 15 and ball-screw 14, and the top of union lever 12 is connected with ball-screw 14, is provided with straight-line guide rail slide block plate 20 between ball-screw 14 and precise ball line slideway 15.Automatic control part comprises driving mechanism and control unit (not shown), and control unit accepts the detection signal of infrared pyrometer 11, and control and drive system work, driving mechanism is connected with described ball-screw 14 by driving syndeton.Driving mechanism comprises stepper-motor or AC servo motor 16, and the output terminal of motor is connected with the input shaft of reduction box 17, and the output shaft of reduction box 17 is connected with ball-screw 14 by synchronizing wheel 19, Timing Belt 18.。
In the present invention, automatic controls movement system cocoa is selected according to actual needs, as long as its can meet at work accurate, drive removable adiabatic regulatory element 9 to carry out moving at a slow speed, its type of drive can be replaced thread screw drives structure, belt pulley drives structure, gear drive structure etc., and those skilled in the art can choose various structures form as required.That is: the concrete structure of vacuum dynamic seal knot, straight-line motion mechanism and automatic control part can be selected, according to actual needs as high vacuum corrugated tube 13 can be replaced high vacuum seal bag structure etc., as long as it meets seal request; As precise ball line slideway 15 and ball-screw 14 can be replaced the structures such as stay cord, belt, rack-and-pinion.
It also can use existing equipment, use an accurate PID setter, such as Erotherm3504, motor driven systems infrared heat being taken into account linear motion system according to the method shown in Fig. 5 removable adiabatic regulatory element formed on a plumbago crucible being moved in burner hearth by the linear motion system outside burner hearth regulates the closed loop automatic control system of plumbago crucible temperature, in patent of the present invention, be called thermal insulation-automatic temperature control system.
Fig. 6 is the structured flowchart of device automatic control electric device part.The temperature T that infrared pyrometer 11 is measured
bas the feedback signal of PID setter, PID setter export to motor driver, the instruction that motor sends according to motor driver is rotated, and regulates the distance controlling temperature T in burner hearth between thermal insulation element and plumbago crucible lid by linear motion device
b, make temperature T
bremain the numerical value that program selector provides.
In the present invention, the electronic machine of the mechanical part and the use of configuration program automatic control system that form linear motion system can be selected according to actual needs, but necessarily reaches the accuracy requirement of SiC Crystal Growth Equipment.Such as, the positioning precision of linear motion system will reach 10 micron dimensions, and mobile accuracy will reach can not have creeping phenomenon (monitoring with dial indicator) when moving with the pole low speed of 0.1mm/h.Electronic instrument precision will reach significant figure 5.
Embodiment 1
(1) as shown in Figure 5, on plumbago crucible lid, installed a mobile regulatory element 9 of thermal insulation playing hot-fluid regulating effect done by solid carbon (graphite) felt or soft (graphite) carbon felt additional, removable adiabatic regulatory element 9 is suspended on joining of graphite bar lower end.Union lever is connected with the Precision Linear Moving system be contained in outside vacuum hearth that following (2) describe by vacuum dynamic seal knot.Can by processing requirement by mobile removable adiabatic regulatory element 9 when growing crystal, the insulation effect above change crucible is to offset because crystal thickness increases the impact brought aufwuchsplate temperature.
(2) equipment of embodiment use as shown in Figure 5, it is upper that it comprises that a high-purity recrystallize alumina tube and stainless steel manufacture, the vacuum chamber that lower seal flange arrangement becomes, by oil-sealed rotary pump, the vacuum system that molecular pump and vacuum degree measurement instrument are formed, by gas pressure sensor, mass flowmeter, electric control valve, the furnace pressure automatic control system that PID setter etc. are formed, by ruhmkorff coil, intermediate frequency power supply, infrared pyrometer, the heating system had that PID setter is formed and high precision output rating automatic control system, induction coil position is moved and corresponding accurate automatic control system, and miscellaneous part is formed.
(3) embodiment uses the thermal insulation element mechanically moving device pressing the forecast scheme configuration shown in Fig. 5 and the program automatic control system formed by the block diagram that Fig. 6 describes with electronic instrument.The micron order product that the major parts ball screw used in mechanism, ball line slideway and motor Dou Shi special manufacturer produce, reduction box is the special product that particular design makes.The PID setter model of tape program setter is Eurotherm3504.
(4) above-mentioned design can use in the SiC Crystal Growth Equipment of other structure types completely.Such as, the SiC Crystal Growth Equipment using the parts such as the Double water-cooled vacuum hearth that made by stainless steel and attached vacuum system, burner hearth pneumatic control system, intermediate frequency power supply and corresponding temperature controlling system to form does basis, installs the program automatic control system that thermal insulation element that this patent provides regulates mechanism and electronic instrument to form additional.
(5) the plumbago crucible diameter of bore that growing crystal uses is 54mm, endoporus height is 100mm, and external diameter is 140mm, makes by high-purity, high-density, high strength graphite.
Load 600 grams of granularities in crucible at 0.1 to 2mm, purity is the silicon carbide polycrystalline powder of 4 more than 9.
The seed crystal used is a slice diameter is 51.2mm, and thickness is about the single-crystal silicon carbide sheet of 0.3-0.5mm, is pasted onto on the internal surface of plumbago crucible upper cover.
Plumbago crucible heat preservation component that is peripheral and bottom is done by high-purity solid carbon felt or soft carbon felt, and diameter is 240mm, is highly 360mm.Have the hole of a placing graphite crucible: upper opening, diameter of bore is 140, is highly 160mm, closed bottom intermediate coaxial.
Upper fixing thermal insulation element above plumbago crucible is made up of the right cylinder of two central aperture: the external diameter of is 240mm below, thickness is 80mm, the cylindrical hole having a diameter 40mm central coaxial; An external diameter is above 240mm, thickness is 60mm, the cylindrical hole having a diameter 90mm central coaxial.Do by graphite felt or solid carbon felt.
The profile of removable adiabatic regulatory element 9 as shown in Figure 5, the forge piece of step type structure be made up of the right cylinder of the concentric connection of three center drillings.Topmost cylindrical diameter is 240mm, highly is 60mm, and middle cylindrical external diameter is 88mm, highly is 60mm, below cylindrical external diameter be 38mm, be highly 40mm.Do by high-purity solid carbon felt or soft carbon felt, have the cylindrical hole of the diameter 15mm leading to light for infrared pyrometer three cylindrical central coaxial.Be suspended on the union lever of graphite making.
The operating frequency of intermediate frequency power supply is 1.5KHz-15KHz, nominal output power 0-50KW.Possesses output rating Program for precision automatic regulation function.
Use the temperature of plumbago crucible during accurate infrared pyrometer monitoring growth crystal.
When crystal growth starts, the lower surface of removable adiabatic regulatory element 9 is apart from heat preservation carbon felt upper surface 45mm on plumbago crucible.
After above-mentioned condition shove charge, use vacuum system that burner hearth inside is extracted into 10
-4after the vacuum tightness of Pa magnitude, close evacuation system, be filled with high-purity Ar gas to 80000Pa.
Start intermediate frequency power supply, the crucible cover temperature that progressively increase heating power detects to infrared pyrometer reaches 1950 ± 5 DEG C, and heating power is now 8-9KW, after temperature equilibrium.After using vacuum pump, within the time of 5-10 minutes, burner hearth air pressure is extracted into 3000 ± 1Pa, start burner hearth air pressure automatic control system and make burner hearth air pressure progressively linearly, equably be reduced to 1200 ± 1Pa from 3000 ± 1Pa in 50 hours of growing crystal.After burner hearth air pressure is extracted into 3000 ± 1Pa, because of burner hearth air pressure reduce, sic powder steam output at high temperature, in plumbago crucible increases fast makes crystal growth began.In process of growth, heating power is made to keep constant by intermediate frequency power supply output rating automatic control system.Process of growth continue 50 hours in, start thermal insulation-temperature controlling system simultaneously, make the temperature of crucible point for measuring temperature from 1950 ° of C in inverse ratio curve drop to 1890 ° of C.The temperature of crucible point for measuring temperature about reduces 60 DEG C, and miles of relative movement is about 30mm, and average rate travel is about 0.5mm/h.
After 50 hours, growth link completes.Cutting off burner hearth air pressure automatic control system and thermal insulation-temperature controlling system and in burner hearth, re-fill Ar gas makes burner hearth air pressure reach air pressure 80-90KPa.Gradually reduce heating power cooling by intermediate frequency power supply output rating automatic control system, until intermediate frequency power supply exports close to after zero output, stop heating.Whole temperature-fall period about 12-24 hours.Leave standstill blow-on after 24 hours again, take out crystal.
By said process, grow diameter 52-56mm that may be used for manufacture 2 inch single-crystal silicon carbide substrate, thickness is about the silicon carbide single crystal of 30mm, and growth velocity is about 0.5mm/h.。
In the multiple and burner hearth used in this example, plumbago crucible and heat-insulation system configure in relevant processing parameter, considerable component structure parameter and growthing process parameter can change within a large range according to different situations, equally also can grow up to the 2 inch single-crystal silicon carbides meeted the requirements.
Embodiment 2
(1) growth apparatus that uses of embodiment 2 and (1), (2) in embodiment 1, (3) are identical with the equipment that (4) describe.
(2) the plumbago crucible diameter of bore that growing crystal uses is 78, endoporus height is 140, and external diameter is 140mm, makes by high-purity, high-density, high strength graphite.
The silicon carbide polycrystalline powder that 800 grams of granularities in the purity of 0.1 to 2mm are 4 more than 9 is loaded in crucible.
The seed crystal used is a slice diameter is 76.2mm, and thickness is about the single-crystal silicon carbide sheet of 0.3-0.5mm, is pasted onto on the internal surface of plumbago crucible upper cover.
Plumbago crucible heat preservation component that is peripheral and bottom is done by high-purity solid carbon felt or soft carbon felt, and diameter is 280--300mm, is highly 480mm.Have the hole of a placing graphite crucible: diameter of bore is 140mm, highly for 200mm, closed bottom intermediate coaxial.
Upper fixing thermal insulation element above plumbago crucible is made up of the right cylinder of two central aperture.The external diameter of one is 240mm below, thickness is 80mm, the cylindrical hole having a diameter 60mm central coaxial; An external diameter is above 240mm, thickness is 60mm, the cylindrical hole having a diameter 120mm central coaxial.Do by graphite felt or solid carbon felt.
The profile of removable adiabatic regulatory element 9 as shown in Figure 5, is made up of the right cylinder of the concentric connection of three center drillings.Topmost cylindrical diameter is 240mm, highly is 60mm, and middle cylindrical external diameter is 118mm, highly is 60mm, below cylindrical external diameter be 58mm, be highly 40mm.Do by high-purity solid carbon felt or soft carbon felt, have the cylindrical hole of the diameter 15mm leading to light for infrared pyrometer three cylindrical central coaxial.Be suspended on the union lever of graphite making, lower to distance crucible 60mm.
The operating frequency of intermediate frequency power supply is 1.5KHz-15KHz, nominal output power 0-50KW.Possesses output rating Program for precision automatic regulation function.
The temperature of plumbago crucible when using accurate infrared heat to take into account high Accuracy PID setter monitoring growth crystal.
After above-mentioned condition shove charge, use vacuum system that burner hearth inside is extracted into 10
-4after the vacuum tightness of Pa magnitude, close evacuation system, be filled with high-purity Ar gas to 80000Pa.
Start intermediate frequency power supply, the crucible cover temperature that progressively increase heating power detects to infrared pyrometer reaches 1950 ± 5 DEG C, and heating power is now about 9-11KW, after temperature equilibrium.After using vacuum pump, within the time of 5-10 minutes, burner hearth air pressure is extracted into 3000 ± 1Pa, start burner hearth air pressure automatic control system and make burner hearth air pressure progressively linearly, equably be reduced to 1200 ± 1Pa from 3000 ± 1Pa in 60 hours of growing crystal.Now, because of burner hearth air pressure reduce, sic powder steam output at high temperature, in plumbago crucible makes crystal growth began by increasing fast.In process of growth, heating power is made to keep constant by intermediate frequency power supply output rating automatic control system; Start thermal insulation-temperature controlling system simultaneously.Process of growth continues 60 hours, the temperature of crucible point for measuring temperature from 1950 DEG C in inverse ratio curve drop to 1890 ° of C.The temperature of crucible point for measuring temperature about reduces 60 DEG C, and miles of relative movement is about 25mm, and average rate travel is about 0.4mm/h.
After 60 hours, growth link completes.Cutting off burner hearth air pressure automatic control system and thermal insulation-temperature controlling system and in burner hearth, re-fill Ar gas makes burner hearth air pressure reach air pressure 80-90KPa.Gradually reduce heating power cooling by intermediate frequency power supply output rating automatic control system, until intermediate frequency power supply exports close to after zero output, stop heating.Whole temperature-fall period about 12-24 hours.Leave standstill blow-on after 24 hours again, take out crystal.
By said process, grow the diameter 78mm that may be used for manufacture 3 inch single-crystal silicon carbide substrate, thickness is about the silicon carbide single crystal of 30mm, and growth velocity is about 0.5mm/h.
In the multiple and burner hearth used in this example, plumbago crucible and heat-insulation system configure in relevant processing parameter, considerable component structure parameter and growthing process parameter can change within a large range according to different situations, equally also can grow up to the 3 inch single-crystal silicon carbides meeted the requirements.
Embodiment 3
(1), in the growth apparatus and the embodiment 1 that use of embodiment 3 (1), (2), the equipment that (3) describe is identical.But employ larger vacuum hearth and induction coil.
(2) the plumbago crucible diameter of bore that growing crystal uses is 106, endoporus height is 160mm, and external diameter is 190mm, makes by high-purity, high-density, high strength graphite.
The silicon carbide polycrystalline powder of 1600 grams of granularities at 0.1 to 2mm is loaded in crucible.
The seed crystal used is a slice diameter is 101.6mm, and thickness is about the single-crystal silicon carbide sheet of 0.3-0.5mm, is pasted onto on the internal surface of plumbago crucible upper cover.
Plumbago crucible heat preservation component that is peripheral and bottom is done by high-purity solid carbon felt or soft carbon felt, and diameter is 300mm, is highly 520mm.Have the hole of a placing graphite crucible: upper opening intermediate coaxial, diameter of bore be 190mm, highly for 210mm, closed bottom.
Upper fixing thermal insulation element above plumbago crucible is made up of the right cylinder of two central aperture.The external diameter of one is 300mm below, thickness is 100mm, the cylindrical hole having a diameter 90mm central coaxial; An external diameter is above 300mm, thickness is 60mm, the cylindrical hole having a diameter 170mm central coaxial.Do by graphite felt or solid carbon felt.
The profile of removable adiabatic regulatory element 9 as shown in Figure 5, the forge piece of step type structure be made up of the right cylinder of the concentric connection of three center drillings.Topmost cylindrical diameter is 300mm, highly is 60mm, and middle cylindrical external diameter is 168mm, highly is 60mm, below cylindrical external diameter be 88mm, be highly 60mm.Do by high-purity solid carbon felt or soft carbon felt, have the cylindrical hole of the diameter 15mm leading to light for infrared pyrometer three cylindrical central coaxial.Be suspended on the union lever of graphite making.Removable adiabatic regulatory element 9 times edges are apart from crucible cover upper surface 70mm.
The operating frequency of intermediate frequency power supply is 1.5KHz-15KHz, nominal output power 0-50KW.Possesses output rating Program for precision automatic regulation function.
The temperature of plumbago crucible when using accurate infrared heat to take into account high Accuracy PID setter monitoring growth crystal.
After above-mentioned condition shove charge, use vacuum system that burner hearth inside is extracted into 10
-4after the vacuum tightness of Pa magnitude, close evacuation system, be filled with high-purity Ar gas to 80000Pa.
Start intermediate frequency power supply, the crucible cover temperature that progressively increase heating power detects to infrared pyrometer reaches 1950 ± 5 DEG C, and heating power is now approximately 13-15KW.After temperature equilibrium, start burner hearth air pressure automatic control system after using vacuum pump to be extracted into 3000 ± 1Pa within the time of 5-10 minutes and make burner hearth air pressure progressively linearly, equably be reduced to 1200 ± 1Pa from 3000 ± 1Pa in 60 hours of growing crystal.Now, because of burner hearth air pressure reduce, sic powder steam output at high temperature, in plumbago crucible makes crystal growth began by increasing fast.In process of growth, heating power is made to keep constant by intermediate frequency power supply output rating automatic control system; Start thermal insulation-temperature controlling system simultaneously.Process of growth continues 80 hours, the temperature of crucible point for measuring temperature from 1950 ° of C in inverse ratio curve drop to 1890 ° of C.The temperature of crucible point for measuring temperature about reduces 60 DEG C, and miles of relative movement is about 18mm, and average rate travel is about 0.23mm/h.
After growth link completes.Cutting off burner hearth air pressure automatic control system and thermal insulation-temperature controlling system and in burner hearth, re-fill Ar gas makes burner hearth air pressure reach air pressure 80-90KPa.Gradually reduce heating power cooling by intermediate frequency power supply output rating automatic control system, until intermediate frequency power supply exports close to after zero output, stop heating.Whole temperature-fall period about 12-24 hours.Leave standstill blow-on after 24 hours again, take out crystal.
By said process, grow the diameter 103-106mm that may be used for manufacture 4 inch single-crystal silicon carbide substrate, thickness is about the silicon carbide single crystal of 30mm, and growth velocity is about 0.4mm/h.。
In the multiple and burner hearth used in this example, plumbago crucible and heat-insulation system configure in relevant processing parameter, considerable component structure parameter and growthing process parameter can change within a large range according to different situations, equally also can grow up to the 4 inch single-crystal silicon carbides meeted the requirements.
Invention main points:
Now widely used with the technology of PVT method grow silicon carbide crystals, structure and the mutual geometric position of the device be made up of the unit such as plumbago crucible and carbon felt class heat-insulating material, parts in burner hearth are fixed in crystal growing process.The temperature of plumbago crucible required for growing crystal being output rating by regulating intermediate frequency power supply, namely realizing by the input energy (thus, have also been changed heat flux Q) of regulation system.The innovative point of invention is that the heat insulating member and growth apparatus that form heat-insulation system have been made important improvement.Be modified to two portions by forming that temperature field in plumbago crucible plays a crucial role, original thermal insulation element after shove charge above fixed crucible cover, one of them can move according to processing requirement in crystal growing process.In crystal growing process, keeping the equivalent thermal resistance being changed this element under the constant condition of heating power by the efficiency configure changed between removable thermal insulation element and plumbago crucible lid, reaching and keeping overcoming crystal structure surface temperature with the thickening and changing problem of crystal under the substantially constant condition of raw materials evaporate temperature.The mechanism system of the present invention's infrared pyrometer, linear motion system and PID setter and removable thermal insulation element form a thermal insulation-temperature reverse feedback automatic control system; In crystal growing process, heating power is kept to remain unchanged, and use thermal insulation-automatic temperature control system to make the numerical value change that the temperature follow procedure of plumbago crucible point for measuring temperature is given, the great variety causing warm field in plumbago crucible because crystal length is thick occurred when balancing out PVT method grow silicon carbide crystals, makes crystal all the time at crystallization impellent P
v-P
mand crystallization interface temperature T
mremain unchanged and (note that crystallization interface temperature T
mnot identical with plumbago crucible point for measuring temperature temperature) ideal conditions under grow.The method calculated by test or digital simulation can by crystallization impellent P
v-P
mand crystallization interface temperature T
mthe requirement remained unchanged provides detected temperatures T
bchange curve and numerical value.Thus reach the object improving the overall homogeneity of crystal, reduce lattice defect, grow up to high quality crystal.
The core of invention plays a crucial role to forming temperature field in plumbago crucible, is originally above fixed crucible cover removable adiabatic regulatory element and is modified to and can move according to processing requirement in crystal growing process, thus by change and distance between plumbago crucible lid, the energy output and reaching that changes plumbago crucible to regulate the method for the object of the warm field in plumbago crucible in the process of crystal growth and for realizing mechanism as be shown in the examples that above-mentioned processing requirement increases on growth apparatus and thermal insulation-automatic temperature control system.Some processing parameters changed in embodiment can not depart from the right of patent of the present invention simply.
Claims (10)
1. the method for a PVT method grow silicon carbide crystals, it is characterized in that, the method is specially: above crucible, arrange removable adiabatic regulatory element, during grow silicon carbide crystals, along with the crystal on crucible cover is long thick, progressively increase the distance D between removable adiabatic regulatory element and crucible cover; Wherein, increase with crystal thickness, crystal is to the thermal resistance R of hot-fluid Q
cto increase; Removable adiabatic regulatory element is to the equivalent thermal resistance R of hot-fluid Q
bincrease with distance D is reduced, by keeping R
cincrease and R
bthe mutual running balance of decrease, ensure that crystallization interface temperature remains unchanged.
2. the device of a grow silicon carbide crystals, it is characterized in that, this device comprises vacuum chamber, crucible, heat-insulation system and thermal insulation element, heat-insulation system is enclosed in circumferential part and the bottom of crucible, thermal insulation element is arranged on the top of crucible, crucible, heat-insulation system and thermal insulation element are all arranged in vacuum chamber, the periphery of vacuum chamber is provided with induction coil, wherein, thermal insulation element comprises thermal insulation element and removable adiabatic regulatory element, upper thermal insulation element is fixedly mounted on the top of crucible cover, removable adiabatic regulatory element is movably arranged on the top of thermal insulation element, removable adiabatic regulatory element can be moved up and down by automatic controls movement Systematical control, removable adiabatic regulatory element moves the distance increasing or reduce between crucible cover, produce and constantly become hot-fluid that is large or that diminish, the hot-fluid total amount adjusted in crucible remains unchanged.
3. the device of grow silicon carbide crystals as claimed in claim 2, it is characterized in that, the top of described vacuum chamber is provided with tongued and grooved flanges, and its central part is provided with the infrared pyrometer for measuring temperature in described crucible.
4. the device of grow silicon carbide crystals as claimed in claim 3, it is characterized in that, the middle part of described upper thermal insulation element and removable adiabatic regulatory element is provided with the thermometer hole suitable with described infrared pyrometer, and described removable adiabatic regulatory element is the forge piece of step type structure be made up of the right cylinder of the concentric connection of three center drillings.
5. the device of grow silicon carbide crystals as claimed in claim 2, it is characterized in that, described automatic controls movement system comprises vacuum dynamic seal knot, straight-line motion mechanism and automatic control part, automatic control part controls straight-line motion mechanism action according to the temperature variation curve that described infrared pyrometer is measured, and straight-line motion mechanism is tied by vacuum dynamic seal and driven described removable adiabatic regulatory element to carry out upper and lower translational motion.
6. the device of grow silicon carbide crystals as claimed in claim 5, it is characterized in that, described vacuum dynamic seal knot comprises union lever and high vacuum corrugated tube, the lower end of union lever is fixedly connected on described removable adiabatic regulatory element, the lower end of high vacuum corrugated tube is sealedly connected on the upper surface of described upper tongued and grooved flanges, and the upper end of high vacuum corrugated tube is sealedly connected on the top of union lever.
7. the device of grow silicon carbide crystals as claimed in claim 6, it is characterized in that, described straight-line motion mechanism comprises precise ball line slideway and ball-screw, and the top of described union lever is connected with ball-screw.
8. the device of grow silicon carbide crystals as claimed in claim 7, it is characterized in that, described automatic control part comprises driving mechanism and control unit, control unit accepts the detection signal of described infrared pyrometer, and control and drive system work, driving mechanism is connected with described ball-screw by driving syndeton.
9. the device of grow silicon carbide crystals as claimed in claim 8, it is characterized in that, described driving mechanism comprises stepper-motor or AC servo motor, and the output terminal of motor is provided with reduction box.
10. the device of grow silicon carbide crystals as claimed in claim 3, it is characterized in that, described automatic controls movement system is arranged on described upper tongued and grooved flanges by erecting frame.
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| CN106637409A (en) * | 2016-12-14 | 2017-05-10 | 珠海鼎泰芯源晶体有限公司 | Silicon carbide crystal growth device |
| CN107557872A (en) * | 2017-10-30 | 2018-01-09 | 中国电子科技集团公司第四十六研究所 | A kind of large size silicon carbide crystals situ heat treatment method |
| CN108130594A (en) * | 2017-12-25 | 2018-06-08 | 中国科学院上海硅酸盐研究所 | A kind of method of the SiC crystal growth interface temperature of real-time monitoring stage by stage and temperature gradient |
| JP7186534B2 (en) | 2018-07-25 | 2022-12-09 | 昭和電工株式会社 | Crystal growth device |
| CN112850714B (en) * | 2021-02-23 | 2022-11-11 | 山东天岳先进科技股份有限公司 | Method and device for preparing silicon carbide powder |
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| CN1544713A (en) * | 2003-11-14 | 2004-11-10 | 中国科学院物理研究所 | Silicon carbide crystal growth apparatus |
| CN200992594Y (en) * | 2006-12-16 | 2007-12-19 | 杭州慧翔电液技术开发有限公司 | Linear rail type crucible lifting device |
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| CN1544713A (en) * | 2003-11-14 | 2004-11-10 | 中国科学院物理研究所 | Silicon carbide crystal growth apparatus |
| CN200992594Y (en) * | 2006-12-16 | 2007-12-19 | 杭州慧翔电液技术开发有限公司 | Linear rail type crucible lifting device |
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