• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
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    • 专利摘要:
    ABSTRACT OF THE DISCLOSUREA silicon carbide single crystal (3) includes nitrogen as a dopant andaluminum as a dopant. A nitrogen concentration is 2x1019 cm* or higher and a ratioof an aluminum concentration to the nitrogen concentration is within a range of 5 %to 40 %. 16
    公开号:SE535452C2
    申请号:SE1150726
    申请日:2011-07-29
    公开日:2012-08-14
    发明作者:Fusao Hirose；Jun Kojima；Kazutoshi Kojima；Tomohisa Kato；Ayumu Adachi；Koichi Nishikawa
    申请人:Denso Corp；
    IPC主号:
    专利说明:

    The present invention relates to a silicon carbide (hereafter referred to asSiC) single crystal. The present invention also relates to a method ofmanufacturing a SiC single crystal and a method of manufacturing a SiC singlecrystal substrate.
    BACKGROUND OF THE INVENTION In recent years, SiCyhas attracted attention as a material of power devicesthat can provide a high breakdown field intensity. SiC semiconductor devices canbe used in controlling high current because the SiC semiconductor devices havehigh field intensity. Therefore, SiC is expected to be applied in control of motorsfor hybrid cars.
    When such SiC semiconductor devices are. manufactured, a SiC singlecrystal wafer is used or a SiC single crystal layer doped with impurities is grown on aSiC single crystal substrate. At this time, for example, to obtain an n-type SiCsingle crystal having low resistance, nitrogen is required to be doped heavily as ann-type dopant. Specifically, a specific resistance demanded for devices is a fewmQcm and nitrogen should be doped heavily to reach this value.
    However, it is confirmed that when nitrogen is doped to a SiC single crystalto reduce a resistance, stacking faults are generated easily if a concentration ofnitrogen is 2x1019 cm'3 or higher. In a case where nitrogen is doped at 2x1019 cm'3,the specific resistance of a device is about 10 mQcm and is a few times higher thanthe specific resistance demanded for devices. The specific resistance of devicesdecreases by doping more nitrogen, however, stacking faults increase substantially 1 to about 800 to 1000 cm'1. resistance component in the manufactured devices and cause a negative effect on The stacking faults become a leak current source or a electric Characteristics of the devices, so it is not just a matter of doping nitrogen.
    JP-A-2008-290898 (corresponding to US 2010/0080956 A1) discioses amethod to reduce generation of stacking faults during a heat treatment of a SiCsingle crystal substrate having low resistance. Specifically, 90 % or greater of thewhole surface of the SiC single crystal substrate is covered by a SiC single crystalplane having surface roughness (Ra) of 1.9 nm or less. Stacking faults aregenerated during the heat treatment which is performed in a case where aconcentration of impurities is increased to reduce the resistance. The generatedamount of stacking faults increases with an increase in the surface roughness.Therefore, in order to inhibit an increase in the generated amount of stacking faults,the surface of the SiC single crystal substrate is covered by a SiC single crystal planehaving a small surface roughness so that a crystal defect is difficult to generate.
    JP-A-10-017399 suggests a manufacturing method of 6H-SiC single crystalin which generation of a micropipe defect is prevented and the amount of stackingfaults is small. Specifically, in a sublimation recrystallization method, a plane of a6H-SiC that is inclined at an angle within :30 degrees from a (11-20) plane towarda (0001) plane and is inclined at an angle within :10 degrees from the (11-20)plane toward a (10-10) plane is used as a seed crystal substrate.
    Although JP-A-2008-290898 suggests the method for inhibiting generationof stacking faults during the heat treatment, stacking faults are already generatedduring doping a great amount of nitrogen prior to the heat treatment. Therefore,the method has no effects unless the stacking faults are inhibited from a step ofdoping. In JP-A-10-017399, SiC of a specific polymorphism having a small amountof stacking faults is manufactured by using a specific plane direction as a growthface. However, the direction of the growth face is specified and the polymorphismof the manufactured SiC is also specified. Therefore, SiC single crystal having asmall amount of stacking faults can be manufactured only in a limited way. Inaddition, it is not clear whether the generated amount of stacking faults can be reduced to a level that the stacking faults do not cause negative effects on electric Characteristics of devices in a case where the doped amount is increased to reducethe resistance. Accordingly, a manufacturing method to reduce a specific resistance and to reduce generation of stacking faults is required.
    SUMMARY OF THE INVENTION In view of the foregoing problems, it is a first object of the present inventionto provide a SiC single crystal in which specific resistance can be reduced and theamount of stacking faults can be reduced. A second object is to provide a methodof manufacturing a SiC single crystal and a third object isto provide a method ofmanufacturing a SiC single crystal substrate.
    According to a first aspect of the present disclosure, a SiC single crystalincludes nitrogen as a dopant and aluminum as a dopant, a nitrogen concentrationis 2x1019 cm* or higher and a ratio of an aluminum concentration to the nitrogenconcentration is within a range of 5 % to 40 0/0.
    In the above SiC single crystal, since nitrogen and aluminum is dopedconcurrently at a predetermined nitrogen concentration and a predetermined Al/Nratio, specific resistance can be reduced and also the amount of stacking faults canbe reduced.
    According to a second aspect of the present disclosure, a method ofmanufacturing a SiC single crystal includes growing a SiC single crystal on a surfaceof a SiC single crystal substrate used as a seed crystal by supplying sublimed gas ofa SiC source material to the surface of the SiC single crystal substrate. Thegrowing the SiC single crystal includes doping nitrogen and aluminum concurrently,a nitrogen concentration is 2x1O19 cm“3 or higher and a ratio of an aluminumconcentration to the nitrogen concentration is within a range of 5 % to 40 %.
    By the method according to the second aspect, the SiC single crystalaccording to the first aspect can be manufactured.
    According to a third aspect of the present disclosure, a method ofmanufacturing a SiC single crystal substrate includes forming a SiC single crystalsubstrate by cutting the SiC single crystal manufactured by the method according to the second aspect.
    The SiC single crystal substrate manufactured by the third aspect can be used as a seed crystal for growing a SiC single crystal.
    BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the presentinvention will become more apparent from the following detailed description madewith reference to the accompanying drawings. In the drawings: FIG. 1 is a diagrammatic cross-sectional view showing a state where a SiCsingle crystal is grown with a SiC single crystal growth apparatus according to a firstembodiment of the present invention; FIG. 2 is a graph showing a relationship between an Al/N ratio and aninhibition ratio of stacking faults; and ' FIG. 3 is a graph showing a relationship between an Al/N ratio and a specific resistance.
    DEFAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described with referenceto FIG. 1.
    The SiC single crystal manufacturing apparatus shown in FIG. 1 is anapparatus in which a SiC single crystal can be grown by an advanced Rayleighmethod. The SiC single crystal manufacturing apparatus has a graphite crucible 1including a hollow cylindrical crucible body la with a bottom and a circular lid 1b.A portion protruding from a center portion of a rear surface of the lid 1b is apedestal 1c, and the SiC single crystal substrate 2 used as a seed crystal is attachedon the surface of the pedestal 1c through, for example, adhesive so that the SECsingle crystal 3 can be grown on the surface of the SiC single crystal substrate 2.
    A plane, for example, having an off angle within a range from 1 degree to 15degrees toward the (0001) C plane is used as a SiC single crystal substrate 2. Thepedestal 1c on which the SiC single crystal substrate 2 is attached has nearly the same size with the SIC single crystal substrate 2. In the present embodiment, theSiC single crystal substrate 2 has a circular shape and also the pedestal 1c has thesame circular shape with the SiC single crystal substrate 2. Additionally, the centerof the pedestal 1c is disposed right above the central axis of 'the crucible 1 so thatthe center of the SiC single crystal substrate 2 is also disposed right above thecentral axis of the crucible 1. Furthermore, the SiC single crystal substrate 2 andthe pedestal 1c can have any shapes, not limited to circles but may be squares,hexagons, octagons or other polygonal shapes.
    A ring member 5 having a skirt-like shape, specifically, having a hollowcircular truncated cone shape is fixed to the lid 1b of the crucible 1 in such a mannerthat the ring member 5 surrounds the pedestal 1c. One end of the ring member 5is disposed on an uneven portion formed on an inner wall of the crucible body la,and a diameter of a growth space gradually increases from the SiC single crystalsubstrate 2 in a growth direction. The ring member 5 can reduce a radialtemperature distribution in the vlcinity of the SiC single crystal substrate 2 andequalize a temperature in the growth space of the SiC single crystal 3 that is grownon the surface of the SiC single crystal substrate 2. In addition, due to the ringmember 5, a temperature of the SiC single crystal substrate 2 and a temperature ofa growth face of the SiC single crystal 3 are lower than other portions.
    In the crucible body 1a, raw material 4 that provides source material ofsublimated gas and includes SiC source powder and aluminum (Al) material isdlsposed. For example, SiC and mixed powder of Si and C having predeterminedparticle diameters can be used as SiC source powder included in the raw material 4,also SIZC or SIC, having predetermined particle diameters can be used as SIC sourcepowder included in the raw material 4. Any material including Al can be used as Almaterial included in the raw material 4. Material including Al and being free ofelements other than constituent element of SiC and constituent element of dopantsuch as AMC; and AIN may be used as Al material.
    Additionally, the crucible 1 is mounted on a rotator which is not shown in thefigure. The rotator rotates around the central axis of the crucible 1, so when the rotator rotates, the crucible 1 mounted on the rotator also rotates around the central axis of the crucible 1. Accordingly, the SiC single crystal substrate 2attached to the pedestal 1c can rotate around the central axis of the crucible 1.
    Furthermore, a heating apparatus, which is not shown in the figure, such asa heater is disposed outside the crucible 1 so as to surround the crucible 1. Thetemperature in the crucible 1 can be adjusted to an appropriate level by controllingthe power of the heating apparatus. For example, when the SiC single crystal 3 isgrown, the temperature of the SiC single crystal substrate 2 used as the seed crystalcan be maintained a temperature lower than the temperature of the raw material 4including the SiC source powder by 10 °C to 200 °C by controlling the power of theheating apparatus. Also it is not shown in the figure, the crucible 1 and other partsare housed in a vacuum chamber in which argon gas and nitrogen (N) used as adopant can be introduced and the whole parts can be heated in the vacuumchamber.
    The SiC single crystal 3 is grown on the growth face of the SiC single crystalsubstrate in the growth space between the SiC single crystal substrate 2 used as theseed crystal and the raw material 4 in the crucible 1, specifically, the spacesurrounded by the ring member 5 having the skirt-like shape by recrystallization ofthe vapor gas sublimated from the SiC source powder included in the raw material 4on the surface of the SiC single crystal substrate 2 with the SiC single crystalmanufacturing apparatus having the above-described structure. An ingot of theSiC single crystal 3 doped with both nitrogen and Al can be manufactured bysupplying nitrogen used as the dopant during the growth of SiC single crystal 3 sothat nitrogen is doped in the SiC single crystal 3 at a high concentration, andgasifying the Al material concurrently in growing the SiC single crystal 3.
    Details of a manufacturing method of the SiC single crystal 3 manufacturedwith the above-described SiC single crystal manufacturing apparatus will bedescribed.
    Firstly, a mixture of SiC source powder and Al material such as AI4C3 powderor AlN powder is disposed in the crucible body la as the raw material 4. Inaddition, the lid lb is disposed on the crucible body la after the SiC single crystal substrate 2 used as the seed crystal is attached to the pedestal lc which is located on the rear surface of the Iid lb. Then argon gas used as growth atmosphere andnitrogen gas used as nitrogen dopant source are introduced into the vacuumchamber concurrently. Then the temperature in the vicinity of the raw material 4 isset to be higher than the subiimation temperature of the SiC source powder and thetemperature in the vicinity of the SiC single crystal substrate 2 used as the seedcrystal is set to be lower than the temperature of the raw material 4 by 10 °C to 200°C by controlling the power of the heating apparatus. Accordingly, the SiC singlecrystal 3 doped with both nitrogen and Al can be grown.
    During the doping, the concentration of nitrogen doped in the SiC singleAdditionally, the ratio of the Al concentration to the nitrogen concentration (hereafter referred to as Al/N ratio) is crystal 3 is set to 2x1019 cm'3 or higher.controlled to within a range of 5 % to 40 %. The Al/N ratio may also be within arange of 10 % to 40 %, and the Al/N ratio may also be within a range of 15 % to40 %. The reasons will be explained with reference to FIG. 2 and FIG. 3.
    In FIG. 2, an inhibition ratio of stacking faults means a ratio of a stackingfault density in a case where the Al is doped to a stacking fault density in a casewhere the Al is not doped under the condition that the nitrogen concentration is thesame.
    The inhibition ratios of stacking faults increase with an increase in the Al/Nratio as shown in FIG. 2, which means that the stacking faults can be inhibited bydoping Al with a ratio higher than a predetermined level during doping nitrogen,and the inhibition effect substantially increases with an increase in the dopedamount of Al. According to experimental results, in a case where the Al/N ratio is5 % or higher, the inhibition effect to stacking faults is started to be achieved, in acase where the Al/N ratio is 10 % or higher, the inhibition ratio can be a high level of40 % or higher and in a case where the Al/N ratio is 15 % or higher, the inhibitionratio can be a very high level of 60 % or higher.
    Accordingly, stacking faults can be reduced by doping Al and nitrogenconcurrently compared with a case where Al is not doped. Although themechanism is uncertain, the mechanism is presumed as follows.
    Carbon in the SiC single crystal 3 is replaced by nitrogen. Because nitrogen has a smaller atomic radius than an atomic radius of silicon (Si), replacement ofcarbon by nitrogen causes a compression effect to the crystal. The compressioneffect increases with an increase in the doped amount of nitrogen and causes adistortion in the atomic arrangement; as a result, stacking faults are generated tokeep the stability of the crystal. Therefore, the compression effect can becompensated by an expansion effect caused by replacement of silicon by Al havinga larger atomic radius than the atomic radius of silicon by doping Al, and generationof the stacking faults can be inhibited.
    Accordingly, in a case where the nitrogen is doped to the SiC single crystal 3at a concentration of 2x1019 cm'3 or higher, the stacking faults of the SiC singlecrystal 3 can be reduced by doping Al with nitrogen concurrently with the Al/N ratioof 5 % or higher. The Al/N ratio may also be 10 % or higher, and the Al/N ratiomay also be 15 % or higher.
    However, the specific resistance (mQcm) increases drastically when theAl/N ratio is increased too high as shown in FIG. 3. Specifically, the specificresistance becomes as high as about 17 mQcm in a case where the Al/N ratio is42 °/@. According to experimental results, the specific resistance increases to 10mQcm or higher in a case where the Al/N ratio is 40 % or higher, and the specificresistance in a case where the Al/N ratio is 40 % or higher is a few times higher thanthe specific resistance in a case where the Al/N ratio is 40 % or lower. Therefore,generation of stacking faults can be inhibited and the specific resistance can bereduced by doping nitrogen and Al concurrently at an Al/N ratio within a range from5 % to 40 %. the Al/N ratio is controlled to a ratio within a range from 10 % to 40 % or a ratio The stacking faults can be inhibited more certainly in a case where within a range from 15 % to 40 %.
    With reference to foregoing findings, in a case where nitrogen is doped tothe SiC single crystal 3, and the concentration of nitrogen is 2x1019 cm'3 or higher,various conditions are set so that the Al/N ratio is within 'the above-described valuerange. For example, when the SiC single crystal 3 is grown by the manufacturingapparatus of a SiC single crystal, a mixture of Al material and SiC source powder in which the ratio of the Al material to the SiC source powder is 45 % is used as the raw material 4. In addition, when the mixture of argon gas used as the growthatmosphere and nitrogen gas used as dopant is introduced into the vacuumchamber, the nitrogen gas is mixed with a ratio of 14 % to the argon gas. Then thetemperature in the vicinity of the raw material 4 is set to approximately 2400 °C andthe temperature in the vicinity of the SiC single crystal substrate 2 used as the seedcrystal is set to approximately 2200 °C and the growth pressure is set to 1.3 kPa bycontrolling the power of the heating apparatus and the growth of SiC single crystal 3is carried out for 100 hours.
    The nitrogen concentration and the Al concentration of the SiC single crystal3 grown in above-described conditions are respectively 4x1019 cm* and 8x1018 cm*and the Al/N ratio is 20 %.
    Furthermore, when the SiC single crystal 3 is cut out at an off angle of 4 degrees, Additionally, the specific resistance is 6 mQcm. and an etch pit density of stacking faults is measured with molten KOH etching, theetch pit density is 45 cm When the density of stacking faults generated in a SiCsingle crystal doped with only nitrogen is measured with the same method, the etchpit density is 250 cm'1, therefore the stacking faults can be reduced by nearly 80 %by doping Al.
    As described above,in a case where the nitrogen is doped to the SiC singlecrystal 3 at a concentration of 2x1019 cm'3 or higher, the stacking faults of SiC singlecrystal 3 can be reduced by doping Al concurrently with nitrogen with the Al/N ratioof 5 % or higher. The Al/N ratio may also be 10 % or higher, and the Al/N ratiomay also be 15 % or higher. Additionally, the specific resistance can be reduced bycontrolling the Al/N ratio to 40 % or lower and a specific resistance demanded fordevices can be obtained. Accordingly, the SiC single ciystal 3, in which a specificresistance demanded for devices can be obtained and the amount of stacking faultscan be reduced, can be obtained.
    A SiC single crystal substrate with a surface of predetermined planedirection having small amount of stacking faults and low specific resistance can beobtained by cutting the SiC single crystal 3 manufactured by the above-describedmanufacturing method along the predetermined plane direction. When a device is formed of the above-described SiC single crystal substrate, negative effects on electric Characteristics of the device are restricted, and high characteristicperformances is obtained. Additionally, the SiC single crystal substrate obtained bythe above-described way can be also used as a new seed crystal to grow a SiCsingle crystal. Because the SiC single crystal having small amount of stackingfaults is used as a seed crystal, a SiC single crystal having small amount of stackingfaults and high characteristic performances can be grown again.
    JP-A-2009-167047 (corresponding to US 2010/0289033 A1) discloses amanufacturing method of a SiC single crystal. In the manufacturing method, whena SiC single crystal ingot is formed, donor-type impurity is doped at a concentrationof2>c101* cm* to 65x10” cm*, acceptor-type impurity is doped at a concentration of1x101* cm* to 5.99x10*° cm*, the concentration of the donor-type impurity isgreater than the concentration of the acceptor-type impurity, and the difference islxlüi* cm* to 5.99x10** cm* so as to reduce basal surface dislocations in the SiCsingle crystal. That is, the basal surface dislocations of the SiC single crystal canbe reduced by doping the donor-type impurity and the acceptor-type impurityconcurrently during the growth of the 5iC single crystal.
    However, the invention in this patent document only aims to reduce theStacking faultsare different from basal surface dislocations in configuration and can not be basal surface dislocations and has no regard to the stacking faults. reduced only by doping the donor-type impurity and the acceptor-type impurityconcurrently. Accordingly, in a case where a SiC single crystal is grown under theconditions described in this patent document, generation of stacking faults can notbe inhibited and the specific resistance can not be reduced as shown in the presentembodiment.
    (Second Embodiment) A second embodiment of the present invention will be described. Because,in the present embodiment, a manufacturing method of a SiC single crystal 3 ischanged from the first embodiment and the other is similar to the first embodiment,only different part will be described.
    The method of growing the SEC single crystal 3 by the advanced Rayleigh method is described in the first embodiment; however, the SiC single crystal 3 can “lÜ be also grown by a deposition method. The manufacturing apparatus of a SiCsingle crystal by the deposition method is a commonly known technology and is notshown by figure. In the manufacturing apparatus, a reaction crucible having acylindrical shape with a lid and made of graphite is disposed in a quartz vacuumchamber. The SiC single crystal substrate 2 used as a seed crystal is attached to arear surface of the lid which is disposed at a top end of the reaction crucible.Source gas and carrier gas are introduced into the reaction crucible through an inletdisposed at a bottom of the reaction crucible. In this way, the SiC single crystal 3 isgrown on the growth face of the» SiC single crystal substrate 2.
    In this deposition method, nitrogen gas and vapor gas sublimated from Almaterial are introduced into the reaction crucible with the SiC source gas so that theSiC single crystal is grown with doping nitrogen and Al concurrently. Also in thiscase, the concentration of nitrogen doped to the SiC single crystal 3 can becontrolled to 2x1019 cm'3 or higher and Al is doped to the SiC single crystal with theAl/N ratio within a range of 5 % to 40 % by controlling a gas flow rate and thepressure of atmospheric gas. The Al/N ratio may also be within a range of 10 % to40 %, and the Al/N ratio may also be within a range of 15 % to 40 %. the SiC single crystal 3 having the specific resistance demanded for devices and In this way, allowing reduction of stacking faults can be obtained.
    For example, when the SiC single crystal 3 is grown by the depositionmethod, source gas including 1.2 SLM of silane and 0.4 SLM of propane isintroduced into the reaction crucible. Concurrently, 10 SLM of hydrogen carriergas, 0.3 SLM of nitrogen gas as nitrogen source and 0.2 SLM of trimethylaluminum(TMA) as Al source are introduced into the reaction crucible. Then thetemperature in the vicinity of the raw material 4 is set to approximately 2400 °C, thetemperature in the vicinity of the SiC single crystal substrate 2 used as the seedcrystal is set to approximately 2250 °C and the pressure in the vacuum chamber isset to 50 kPa by controlling the power of heating apparatus and then the growth ofSiC single crystal 3 is carried out.
    The nitrogen concentration and the Al concentration of the SiC single crystal 3 grown in above-described conditions are respectively 6x1019 cm'3 and 2x1019 cm'3 11 and the Al/N ratio is 33 %.
    Furthermore, when the SiC single crystal 3 is cut out at an off angle of 4 degrees, Additionally, the specific resistance is 4 mQcm. and an etch pit density of stacking faults is measured with molten KOH etching, theetch pit density is 17 cm'1. When the density of stacking faults generated in a SiCsingle crystal doped with only nitrogen is measured with the same methoddescribed above, the etch pit density is 300 cm"1, therefore the stacking faults canbe reduced by nearly 95 % by doping Al.
    (Third Embodiment) A third embodiment of the present invention will be described. Because,also in the present embodiment, a manufacturing method of a SiC single crystal 3 ischanged from the first embodiment and the other is similar to the first embodiment,only different part will be described.
    The SiC single crystal 3 can be also grown by a hot-wall CVD method. In acase where a SiC single crystal 3 is grown by the hot-wall CVD method, a SiC singlecrystal film is formed as the SiC single crystal 3 on the growth face of the SiC singlecrystal substrate 2. A growth apparatus (CVD apparatus) of the single crystal filmbased the hot-wall CVD method is a commonly known technology and is not shownby figure. In the CVD apparatus, a susceptor made of graphite is disposed inside aquartz vacuum chamber. The SiC single crystal 3 (single crystal film) can beepitaxially grown on the growth face of the SiC single crystal substrate 2 by heatingthe SiC single crystal substrate 2 which is mounted on the susceptor andconcurrently introducing SiC source gas and carrier gas into the vacuum chamberthrough an inlet of the source gas.
    In this hot-wall CVD method, nitrogen gas and vapor gas sublimated from Almaterial are introduced into the reaction crucible with the SiC source gas so that theSiC single crystal 3 is grown with doping nitrogen and Al concurrently. Also in thiscase, the concentration of nitrogen doped to the SiC single crystal 3 can becontrolled to 2x1019 cm'3 or higher and the Al is doped to the SiC single crystal withthe Al/ N ratio within a range of 5 % to 40 % by controlling the gas flow rate and thepressure of atmospheric gas. The Al/N ratio may also be within a range of 10 % to40 %, and the Al/N ratio may also be within a range of 15 % to 40 %. In this way, 12 the SiC single crystal 3 having a specific resistance demanded for devices andallowing reduction of stacking fauits can be obtained on the surface of the SiC singlecrystal substrate 2. That is, an epitaxial SiC substrate including the SiC singlecrystal 3, in which nitrogen is doped at a concentration of 2x1019 cm"3 or higher andthe Al/N ratio is within a range of 5 % to 40 %, is epitaxially grown on a single sideof the SiC single crystal substrate 2 can be obtained.
    For example, when the SiC single crystal 3 is grown by the hot-wall CVDmethod, source gas including silane and propane is introduced with hydrogen ascarrier gas into the reaction crucible. In addition, nitrogen gas as nitrogen sourceand trimethylaluminum (TMA) as Al source are also introduced into the reactioncrucible. Then the temperature of SiC single crystal substrate 2 is set toapproximately 1650 °C and the pressure in the vacuum chamber is set to 10 kPa bycontrolling the power of heating apparatus and the growth of SiC single crystal 3 iscarried out.
    The nitrogen concentration and the Al concentration of the SiC single crystal3 grown in above-described conditions are respectively 2x102° cm'3 and 5x1019 cm'3and the Al/N ratio is 28 %.
    Furthermore, when the SiC single crystal is cut out at an off angle of 4 degrees, and Additionally, the specific resistance is 5 mQcm. an etch pit density of stacking fauits is measured with molten KOH etching, the etchpit density is 75 cm'1. When the density of stacking fauits generated in a SiC singlecrystal doped with only nitrogen is measured with the same method, the etch pitdensity is 800 cm'1, therefore the stacking fauits can be reduced by nearly 90 % bydoping Al.
    (Other Embodiments) In each of the above-described embodiments, an example of growing theSiC single crystal 3 by the advanced Rayleigh method, the deposition method or thehot-wall CVD method is described. However, the conditions described in each ofthe above-described embodiments are merely examples. By changing variousgrowth conditions appropriately, the concentration of nitrogen doped to the SiCsingle crystal 3 can be controlled to 2x1019 cm'3 or higher and the Al is doped to the SiC single crystal 3 with the Al/N ratio within a range of 5 % to 40 °/0. The Al/N 13 ratio may also be within a range of 10 % to 40 %, and the Al/N ratio may also bewithin a range of 15 % to 40%.
    Also in the second and the third embodiments, a SiC single crystal substratewith a surface of predetermined plane direction having small amount of stackingfaults and low specific resistance can be obtained by cutting the SiC single crystal 3manufactured by each method along the predetermined plane direction asdescribed in the first embodiment. Additionally, a SiC single crystal substrate canbe grown using the SiC single crystal substrate manufactured by the above-described way as a new seed crystal. 14
    权利要求:
    Claims (5)
    [1] 1. A silicon carbide single crystal (3) comprising: nitrogen as a dopant; and aluminum as a dopant, wherein a nitrogen concentration is 2x1019 cm* or higher, and wherein a ratio of an aluminum concentration to the nitrogen concentration is Within a range of 5 % to 40 %.
    [2] 2. The silicon carbide single crystal (3) according to claim 1,wherein the ratio of the aluminum concentration to the nitrogen concentration is 10 % or higher.
    [3] 3. The silicon carbide single crystal (3) according to claim 1,wherein the ratio of the aluminum concentration to the nitrogen concentration is 15 % or higher.
    [4] 4. A method of manufacturing a silicon carbide single crystal (3) comprisinggrowing a silicon carbide single crystal (3) on a surface of a silicon carbide single crystal substrate (2) used as a seed crystal by supplying sublimed gas of asilicon carbide source material to the surface of the silicon carbide single crystalsubstrate (2), wherein the growing the silicon carbide single crystal (3) includes dopingnitrogen and aluminum concurrently, and wherein a nitrogen concentration is 2x1019 cm'3 or higher and a ratio of analuminum concentration to the nitrogen concentration is within a range of 5 % to40 %.
    [5] 5. A method of manufacturing a silicon carbide single crystal substrate comprisingforming a silicon carbide single crystal substrate by cutting the silicon carbide single crystal (3) manufactured by the method according to claim 4.
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    同族专利:
    公开号 | 公开日
    US20120025153A1|2012-02-02|
    US9053834B2|2015-06-09|
    CN102400224A|2012-04-04|
    DE102011079855A1|2012-02-02|
    JP5839315B2|2016-01-06|
    CN102400224B|2015-04-01|
    DE102011079855B4|2018-06-07|
    SE1150726A1|2012-01-31|
    JP2012031014A|2012-02-16|
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