JP4691815B2 - Method for producing SiC single crystal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a SiC single crystal that can be used for a material such as a semiconductor device or a light emitting diode.
[0002]
[Prior art]
Conventionally, a sublimation method has been widely used as a method for growing a SiC single crystal. In this sublimation recrystallization method, a seed crystal is joined to a graphite pedestal placed in a graphite crucible, and the SiC raw material powder arranged at the bottom of the crucible is heated and sublimated, and the sublimated gas is recrystallized on the seed crystal. It is to make it.
[0003]
However, when a SiC single crystal is grown so as to maintain good quality by the current sublimation recrystallization method, the growth rate is as slow as several hundred μm / h, and conversely as the growth rate is as high as several mm / h. However, there is a problem that the crystallinity deteriorates to become polycrystalline. For example, in Materials Science and Engineering B46 (1997) 296-299, the relationship between the growth rate and the micropipe density is shown, and several hundred pieces / cm at a growth rate of 0.7 mm / h.²The micropipe density was several thousand pieces / cm at a growth rate of 1.4 mm / h.²It has been reported that
[0004]
Therefore, in Japanese Patent Publication No. 7-88274, the seed crystal temperature is 2200 to 2400 ° C., the raw material temperature is 2300 to 2500 ° C., and the pressure is 1.33 × 10 6.²~ 1.33 × 10^ThreeThe solution to the above problem is attempted by setting the Pa (1 to 10 Torr) to be concentrated and guiding the sublimation gas onto the surface of the drawn seed crystal by a concentration means made of graphite. It has been reported that crystals having good crystallinity were obtained at a growth rate of 1 to 2 mm / h.
[0005]
[Problems to be solved by the invention]
In order to obtain good crystals, it is necessary that the gas is sufficiently supplied and that the supplied gas reacts appropriately on the growth surface. On the other hand, in the method disclosed in the above-mentioned conventional publication, a device is provided by supplying a gas, but a device for appropriately reacting the supplied gas on the growth surface has not been made. The crystallinity of the material deteriorates and becomes polycrystallized.
[0006]
The present invention has been made in view of the above problems, and provides a method for producing a SiC single crystal that allows a supplied gas to appropriately react on a growth surface and can perform growth with good crystallinity even at a high growth rate. With the goal.
[0007]
[Means for Solving the Problems]
The present inventors presume that the above problem (degradation of crystallinity due to an increase in growth rate) is caused by three steps of two-dimensional nucleus generation, two-dimensional nucleus growth, and two-dimensional nucleus collision, A method for suppressing the generation of two-dimensional nuclei was examined.
[0008]
In order not to generate the two-dimensional nucleus, it is necessary that the adsorbed atoms (molecules) reach the position of the kink by surface migration and be taken into the crystal there. There are two ways to make the adsorbed atoms (molecules) incorporated into the crystal in this way. The first is to reduce crystal defects that become resistance to surface migration and increase the free path of adsorbed atoms (molecules). As a result, the adsorbed atoms (molecules) can reach the kink position and can be crystal-grown satisfactorily. The second is to activate by increasing the temperature of the growth surface and increase the migration rate. As a result, the adsorbed atoms (molecules) in the atmosphere can quickly move to the kink position, and even if the atoms (molecules) are adsorbed on the surface of the crystal one after another, the crystal can be grown well.
[0009]
However, when crystal growth is performed simply by raising the temperature of the crystal surface, fluctuations in the initial growth increase due to the higher temperature and the defect density increases, so the free path of adsorbed atoms becomes shorter and the crystallinity deteriorates. On the contrary, during the growth, when the crystal surface is heated, the surface migration rate is increased and the crystallinity is improved.
[0010]
Actually, dislocation density during initial growth is 1 × 10^FivePiece / cm²The crystal grown at a growth rate of 2.5 mm / h does not generate new defects and grows well (dislocation density is constant), whereas the dislocation density during initial growth is 1 × 10.⁶Piece / cm²As a result, the crystal quality of the crystal grown at a growth rate of 2.5 mm / h deteriorated as the crystal grew, resulting in polycrystallization.
[0011]
  Therefore, in the invention described in claim 1, the SiC seed crystal (2) is disposed in the container (1), and a raw material gas is supplied to the surface of the SiC seed crystal, so that the SiC seed crystal has a SiC surface on the surface. In the method for producing a SiC single crystal for growing a single crystal, the dislocation density of the SiC single crystal is 1 × 10 6 on the surface of the SiC seed crystal.^FivePiece / cm²The first step of growing so as to be the following, and after the first step, at a growth rate faster than the first stepAnd the upper limit of the growth rate is 3 mm / hAnd a second step of growing the SiC single crystal.When the transition from the first step to the second step is performed, the timing at which the temperature of the SiC single crystal surface is shifted from the first step condition to the second step condition is determined from the source gas supply condition from the first step condition. The dislocation density at the initial stage of the growth of the SiC single crystal is 1 × 10 6 by growing the growth rate at 0.5 mm / h or less in the first step so as to be earlier than the timing for shifting to the condition of the second step. ^Five Piece / mm ² Growing a SiC single crystal of at least 100 μm or more in the first stepIt is characterized by.
  In this way, a good SiC single crystal can be obtained efficiently by performing growth with a low dislocation density in the first step and changing the growth rate of the SiC single crystal between the first step and the second step.When the transition from the first step to the second step is performed, the timing at which the temperature of the SiC single crystal surface is shifted from the first step condition to the second step condition is determined by changing the source gas supply condition from the first step condition. By making it earlier than the timing for shifting to the condition of the second step, it is possible to shift from the first step to the second step with a margin for the surface migration speed, and from the first step to the second step. Defects that occur during the transition to the process can be suppressed. Further, in the first step, by setting the growth rate to 0.5 mm / h or less, defects generated during initial growth can be reduced, and a SiC single crystal can be grown with high quality. Furthermore, by performing the first step for 10 minutes or more, the first step can be stabilized, and the second step can be performed after the occurrence of defects in the first step is suppressed.
[0012]
  In the invention according to claim 2, the SiC seed crystal (2) is arranged in the container (1), and a raw material gas is supplied to the surface of the SiC seed crystal, so that an SiC single crystal is formed on the surface of the SiC seed crystal. In the method for producing a SiC single crystal, the dislocation density of the SiC single crystal is 1 × 10 6 on the surface of the SiC seed crystal. ^Five Piece / cm ² A first step of growing so as to become: a second step of growing a SiC single crystal after the first step at a growth rate faster than that of the first step and with the upper limit of the growth rate being 3 mm / h; When the transition from the first step to the second step is performed, the timing at which the temperature of the SiC single crystal surface is shifted from the first step condition to the second step condition changes the source gas supply condition of the first step. The dislocation density at the initial stage of the growth of the SiC single crystal is 1 by increasing the growth rate at 0.5 mm / h or less in the first step so as to be earlier than the timing for shifting from the condition to the condition for the second step. × 10 ^Five Piece / mm ² The SiC single crystal is grown to at least 100 μm or more by the first step as follows.
As described above, the first step can be stabilized by growing at least 100 μm or more of the SiC single crystal in the first step, and the second step is performed after the generation of defects is suppressed in the first step. be able to.
  Claim3In the described invention,In the second step,After the first step, the growth crystal surface temperature is made higher than that in the first step to grow the SiC single crystal.RukoAnd features.
  As described above, by performing growth in which the dislocation density is lowered in the first step and changing the growth temperature of the SiC single crystal in the first step and the second step, a good SiC single crystal can be obtained efficiently.
[0013]
  The first step can be performed at any time during the growth of the SiC single crystal.4As shown in FIG. 5, a good SiC single crystal can be obtained efficiently by performing the first step in the initial stage of growth.
[0016]
  Claim5The described invention is characterized in that the growth rate in the second step is at least five times the growth rate in the first step.
  In this way, a SiC single crystal can be grown slowly and with high quality at an early stage of growth, and then a good SiC single crystal can be obtained efficiently by increasing the growth rate.
[0017]
  Claim6The described invention is characterized in that the temperature of the surface of the SiC single crystal in the second step is 2500 ° C. or higher.
  Thereby, the surface migration speed | velocity | rate in a 2nd process can be made quick and a favorable SiC single crystal can be grown.
[0018]
  Claim7The described invention is characterized in that the temperature of the SiC single crystal surface in the second step is set to be 100 ° C. or more higher than the temperature of the SiC single crystal surface in the first step.
  Thereby, the SiC single crystal can be favorably grown at a low temperature with good controllability in the initial growth, and then a good SiC single crystal can be efficiently obtained by increasing the growth rate at a high temperature.
[0019]
  Claim8In the described invention, the dislocation density of the SiC single crystal in the second step is 1 × 10^FivePiece / cm²It is characterized by being as follows.
  Thereby, the SiC single crystal can be grown while satisfying the condition that no new defect is generated during the growth, and the high-quality SiC single crystal can be stably grown.
[0020]
  Claim9In the described invention, as a method of supplying a raw material gas to the surface of the SiC seed crystal, a sublimation method in which a SiC powder raw material is heated and sublimated is used, and the temperature of the SiC powder raw material in the second step is 2600 ° C. or higher. To do.
  By doing in this way, source gas can be supplied to the surface of a SiC seed crystal at high speed, and a SiC single crystal can be grown well at high speed.
[0021]
  Claim10In the described invention, the temperature difference between the SiC powder raw material and the SiC single crystal surface in the first step is within 100 ° C., and the temperature difference between the SiC powder raw material and the SiC single crystal surface in the second step is 200 ° C. It is characterized by the above.
  Thereby, in the first step, it is possible to reduce fluctuations that are likely to occur in the initial stage of growth and grow a good SiC single crystal. In the second step, the growth rate is increased while maintaining the quality of the initial growth, and the SiC is increased. Single crystals can be grown.
[0022]
  Claim11The invention described in item 1 is characterized in that the growth rate of the SiC single crystal in the second step is 2.5 mm / h or more.
  As a result, it is possible to efficiently grow a SiC single crystal while maintaining good crystallinity.
[0024]
  Claim12In the invention described in the above, when shifting from the first step to the second step, the transition from the growth condition of the first step to the growth condition of the second step is continuously performed over a period of 30 minutes or more. To do.
  Thereby, the defect which generate | occur | produces in the transition period of a 1st process to a 2nd process can be suppressed.
[0025]
  Claim13In the first aspect, in the first step, the partial pressure of the gas species used as the atmospheric gas is made larger than the partial pressure of the raw material gas, and in the second step, the partial pressure of the gas species used as the atmospheric gas is set as the raw material. It is characterized by being smaller than the partial pressure of the gas.
  As described above, in the first step, the atmospheric gas is present in a larger amount than the raw material gas in the atmosphere, thereby utilizing the increase in the scattering of the raw material gas by the atmospheric gas and the speed at which the raw material gas reaches the SiC single crystal surface. Can slow down. For this reason, a supersaturation degree can be suppressed and a SiC single crystal can be made to grow well. Further, in the second step, by reducing the atmosphere gas and increasing the source gas, scattering of the source gas can be reduced and a large amount of source gas can be supplied to the surface of the SiC single crystal. For this reason, a SiC single crystal can be grown at high speed.
[0026]
  Claim14In the described invention, in the second step, at least one gas of hydrogen, oxygen, and chlorine is introduced as an atmospheric gas.
  Thereby, it is possible to selectively etch the two-dimensional nuclei generated during the growth of the SiC single crystal, and to obtain a good SiC single crystal in which the two-dimensional nuclei are suppressed.
[0027]
  Claim15In the described invention, a plane inclined from the c-plane is used as a seed crystal. Thereby, the density of steps appearing on the growth surface of the SiC single crystal can be increased, and a good SiC single crystal can be grown at a higher speed.
[0028]
  Claim16In the described invention, the temperature of the surface of the SiC single crystal is set to 2400 ° C. or lower in the first step, so that the SiC single crystal is 4H—SiC.
  Thus, by setting the surface temperature of the single crystal to 2400 ° C. or less, 4H—SiC can be easily formed. After producing good 4H—SiC, good 4H—SiC growth in the second step By increasing the speed and growing, good 4H—SiC can be obtained efficiently.
[0029]
In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 shows a cross-sectional configuration of the single crystal manufacturing apparatus used in the first embodiment of the present invention. Hereinafter, the configuration of the single crystal manufacturing apparatus will be described with reference to FIG.
[0031]
As shown in FIG. 1, the single crystal manufacturing apparatus includes a growth vessel 1 made of graphite composed of a vessel main body 1a and a lid 1b. In the growth container 1, an SiC seed crystal 2 is disposed so as to be attached to the back surface of the lid 1b, and an SiC single crystal grows on the surface of the SiC seed crystal 2. Moreover, the SiC powder raw material 3 used as the supply source of sublimation gas is arrange | positioned at the bottom part of the container main body 1a among the growth containers 1. FIG.
[0032]
Furthermore, a heat insulating material 4 is disposed on the outer periphery of the growth vessel 1, and the entire vessel including the heat insulating material 4 is surrounded by a quartz reaction tube 5. A high-frequency induction coil 6 is disposed on the outer periphery of the quartz reaction tube 5, and the growth vessel 1 can be heated by supplying a high-frequency current to the induction coil 6. An inert gas introduction tube 7 is provided in the quartz reaction tube 5 so that an inert gas such as Ar gas serving as an atmospheric gas can be introduced.
[0033]
Although not shown, an exhaust mechanism such as a vacuum pump is connected to the quartz reaction tube 5, and the exhaust in the quartz reaction tube 5 can be performed by this exhaust mechanism. Here, an example is shown in which the SiC powder raw material 3 is disposed as a raw material, but the present invention is not limited to this, and for example, a Si-containing gas and a C-containing gas may be introduced from the outside. Similarly, the heating device is not limited to the high-frequency heating device, and for example, a resistance heating device may be used. However, since the container can be directly heated by using a high-frequency heating device, it is desirable to use a high-frequency heating device in order to achieve the high temperature that is one of the features of the present invention.
[0034]
Next, the manufacturing process of the SiC single crystal by the single crystal manufacturing apparatus having the above configuration will be described.
[0035]
First, the inside of the growth vessel 1 is evacuated using the exhaust mechanism, and the inside of the growth vessel 1 is brought to a predetermined temperature by the high frequency coil 6. Thereafter, an inert gas such as Ar gas is introduced through the inert gas introduction pipe 7. Then, while maintaining the inside of the quartz reaction tube 5 at a predetermined pressure, the temperature of the growth surface of the SiC seed crystal 2 and the temperature of the SiC powder raw material 3 are raised to the target temperature. For example, when the growth crystal is 4H—SiC, the temperature of the growth crystal surface is set to 2200 to 2400 ° C., and the temperature of the SiC powder raw material 3 is set to about 10 to 100 ° C. higher than the temperature of the growth crystal surface. At this time, if the temperature for raising the growth crystal surface with respect to the SiC powder raw material 3 is set to 100 ° C. or less, fluctuations that are likely to occur at the initial stage of growth are reduced, and good crystal growth can be achieved.
[0036]
Then, as a first step, the inside of the quartz reaction tube 6 is depressurized using an exhaust mechanism to obtain 6.65 × 10 6.^Three~ 1.33 × 10^FourA single crystal is grown on the surface of the SiC seed crystal 2 at a growth rate of, for example, 0.5 mm / h or less, preferably about 0.4 mm / h at Pa (50 to 100 Torr). Thereby, the dislocation density 1 × 10^FivePiece / cm²A single crystal grows below.
[0037]
In this first step, if the inert gas in the atmosphere is present in a larger amount than the source gas, scattering of the source gas by the inert gas can be increased, and the rate at which the source gas reaches the crystal surface is reduced. It is possible to suppress the degree of supersaturation and to grow a better single crystal.
[0038]
Thereafter, as the second step, when the growth of the single crystal is stabilized, for example, when the first step is performed for 10 minutes or more or when the single crystal is grown by 100 μm or more, the temperature of the grown crystal surface is higher than that in the first step. Also, the temperature is raised to 2500 ° C. or higher, for example, 2500 to 2600 ° C., which is 100 ° C. or higher, and the temperature of the SiC powder raw material 3 is set to 200 ° C. or higher, for example, 2600 ° C. or higher, than the temperature of the growth crystal surface. At this time, the pressure is 1.33 × 10²~ 4x10^ThreeThe pressure is reduced to Pa (1 to 30 Torr), and the single crystal is grown at a growth rate of 2.5 to 3 mm / h. As a result, the single crystal grows at a growth rate higher than that of the first step, for example, about five times the growth rate of the first step. However, while maintaining the crystallinity formed in the first step, a good single crystal is obtained. Crystal grows.
[0039]
In this second step, by reducing the inert gas in the atmosphere and increasing the source gas, it is possible to reduce the scattering of the source gas, so that a large amount of source gas can be supplied to the growth crystal surface, A single crystal can be grown at a high growth rate.
[0040]
Thus, in the initial stage of growth, a good single crystal is grown in the first step, and thereafter, the single crystal is grown at a high growth rate in the second step. For this reason, a good single crystal can be grown in advance in the first step, and a good single crystal can be grown even if the growth rate is increased in the second step. In the second step, since the temperature of the growth crystal surface is set higher than that in the first step, a good single crystal can be grown even if the growth rate is high. According to experiments, it has been confirmed that even when the growth rate in the second step is 2.5 mm / h or more, a single crystal can be efficiently formed while maintaining good crystallinity.
[0041]
In addition, when shifting from the first step to the second step, if the timing for shifting the temperature of the growth crystal surface is made faster than the timing for controlling raw material supply (for example, raw material temperature, raw material supply amount, etc.), the surface migration speed Therefore, it is possible to shift from the first process to the second process while keeping a margin, and it is possible to suppress defects that occur during the transition from the first process to the second process.
[0042]
(Second Embodiment)
FIG. 2 shows a cross-sectional configuration of a single crystal manufacturing apparatus used in the second embodiment of the present invention. Here, differences from the first embodiment will be described. In the second embodiment, a gas introduction pipe 9 is attached as an inlet for the source gas and the atmospheric gas, the SiC powder raw material 3 (see FIG. 1) used in the first embodiment is not used, and the source gas is SiH._FourAnd C_ThreeH₈Is used. In addition to the inert gas Ar as the atmospheric gas, H₂Is used.
[0043]
Next, the manufacturing process of the SiC single crystal by the single crystal manufacturing apparatus having the above configuration will be described.
[0044]
First, the inside of the growth vessel 1 is evacuated using the exhaust mechanism, and the inside of the growth vessel 1 is brought to a predetermined temperature by the high frequency coil 6. After that, through the gas introduction pipe 9₂Gas or Ar gas is introduced to raise the temperature of the growth surface of the SiC seed crystal 2 to the target temperature. For example, the Ar flow rate is set to 2 SLM, and the pressure in the quartz reaction tube 5 is set to 500 Torr. At this time, for example, when the growth crystal is 4H—SiC (000-1), the temperature of the growth crystal surface is set to 2200 to 2400 ° C.
[0045]
When this temperature is reached, as a first step, SiH that becomes a source gas from the gas introduction pipe 9_Four250 sccm, C_ThreeH₈Is introduced at a rate of about 0.4 mm / h.
[0046]
Thereafter, when the growth is stabilized, as a second step, the growth crystal surface temperature is increased to 2500 to 2600 ° C., and SiH_Four2SLM, C_ThreeH₈0.56 SLM and the introduction amount are increased, and Ar is reduced by 1 SLM and the introduction amount is decreased, and the growth crystal is grown at a growth rate of 2.5 to 3 mm / h.
[0047]
Thus, SiH as the source gas_FourAnd C_ThreeH₈In addition to Ar, which is an inert gas, as an atmospheric gas, H₂Even if it uses, the effect similar to 1st Embodiment is acquired, and a SiC single crystal with favorable crystallinity can be obtained similarly to 1st Embodiment.
[0048]
(Other embodiments)
In the first embodiment, the growing atmospheric gas is Ar, but a trace amount of hydrogen, oxygen, or chlorine gas may be mixed therewith. Also in the second embodiment, a trace amount of oxygen or chlorine gas may be mixed. By introducing these gases, two-dimensional nuclei whose surface is exposed can be selectively etched, so that two-dimensional nucleation is suppressed and a better growth crystal can be obtained.
[0049]
In the first and second embodiments, an off substrate inclined from the c-plane as the seed crystal plane orientation may be used. By using such an off substrate, it is possible to increase the step density on the surface of the grown crystal, and thus it is possible to achieve good crystal growth.
[0050]
In the first and second embodiments, the first step is the initial growth stage, but the dislocation density is 1 × 10.^FivePiece / cm²From the above state, the dislocation density is decreased during growth to 1 × 10^FivePiece / cm²After the following, the first step may be performed.
[0051]
【Example】
Example 1
In order to confirm the effect of the first embodiment, an SiC single crystal was grown according to the method described above using the apparatus shown in FIG.
[0052]
Specifically, 4H-SiC single crystal (000-1) was used as seed crystal 2, and the first step was performed for 1 hour and the second step was performed for 5 hours. And the transition time from the 1st process to the 2nd process was performed over 40 minutes. The distance between the surface of the SiC seed crystal 2 and the surface of the SiC powder raw material 3 was 30 mm.
[0053]
First, the inside of the growth vessel 1 is evacuated by an exhaust mechanism and heated to 900 ° C., and then the pressure in the quartz reaction tube 5 is 6.65 × 10 6 while introducing Ar from the inert gas introduction tube 7.^FourThe temperature was maintained at Pa (500 Torr) until the surface temperature of the seed crystal 2 as the initial crystal growth surface was 2250 ° C. and the temperature of the SiC powder raw material 3 was 2300 ° C.
[0054]
Thereafter, as a first step, the inside of the quartz reaction tube 5 is gently depressurized, and the atmospheric pressure is 1.33 × 10 6.^FourThe material gas was set to Pa (100 Torr), the material gas was sublimated from the SiC powder material 3, and grown for 1 hour. When another experiment was performed under the same conditions as described above, and a SiC single crystal was grown only by the first step, the growth rate was 0.28 mm / h, and the dislocation density was 4 × 10.^FourPiece / cm²Met.
[0055]
Next, as a second step, the temperature of the growth crystal surface is increased to 2500 ° C., the temperature of the SiC powder raw material 3 is 2700 ° C., and the pressure is 4 × 10 6.^ThreeGrowth was performed at Pa (30 Torr). Then, the transition timing from the first step to the growth condition of the second step is that the temperature of the growth crystal surface is 20 minutes immediately after the start of the transition, and the temperature of the SiC powder raw material 3 is 5-30 min. Each condition was gradually shifted between 20 and 40 ml.
[0056]
At this time, since the temperature of the surface of the grown crystal is increased by 250 ° C., the surface migration rate is increased and more crystals can be taken up. Then, the temperature of the SiC powder raw material 3 is raised by 400 ° C. to supply more raw material. Further, by reducing the pressure when the temperature is stabilized, more source gas can be supplied.
[0057]
In the first step, the atmospheric pressure is 1.33 × 10 6.^FourPa (100 Torr), 4 × 10 of the partial pressure of SiC powder raw material 3 (2300 ° C.)²Since it is set to Pa (3 Torr) or more, the diffusion of the raw material gas sublimated from the SiC powder raw material 3 can be controlled, and the initial growth can be stabilized.
[0058]
On the other hand, in the second step, the atmospheric pressure is 4 × 10.^ThreeIn contrast to Pa (30 Torr), the partial pressure of SiC powder raw material 3 at 2700 ° C. is 2.66 × 10 6.^FourSince it is as large as Pa (220 Torr), the raw material gas sublimated from the SiC powder raw material 3 reaches the surface of the grown crystal freely without being scattered by the atmospheric gas, and the supply speed of the raw material is increased.
[0059]
The growth crystal obtained through such a growth time of 40 minutes for a total time of 6 hours was a long amount of 17 mm. From this, it was found that the growth rate in the second step was about 3 mm / h. In addition, as a result of obtaining the dislocation density after cutting the growth crystal several times in the growth direction parallel to the c-plane and performing KOH etching on the obtained growth crystal, the dislocation density is constant from the initial growth stage to the late growth stage. 6 × 10 in value^FourPiece / cm²Met. Therefore, the dislocation density is 1 × 10 5 even under the condition where the growth rate is 3 mm / h.^FivePiece / cm²It can be said that the following high-quality crystals could be grown.
[0060]
(Example 2)
In order to confirm the effect of the second embodiment, an SiC single crystal was grown according to the method described above using the apparatus shown in FIG.
[0061]
Specifically, an SiC seed crystal 2 similar to that in Example 1 is used, and an SiC single crystal is basically grown under the same conditions as in Example 1. However, the conditions are changed for the following points. . This different part will be described.
[0062]
First, the inside of the growth vessel 1 is evacuated by the exhaust mechanism, and then H₂The growth crystal surface is raised to 1400 ° C. while introducing 1 SLM of gas. Then H₂The introduction of the gas is stopped, and the surface of the grown crystal is further heated to 2250 ° C. while introducing 2 SLM of Ar gas. Then, when the temperature of the growth crystal surface is stabilized, the first step is SiH as a source gas._Four250 sccm, C_ThreeH₈Was gradually introduced and grown for 1 hour.
[0063]
Next, as a second step, the temperature of the growth crystal surface is increased to 2500 ° C., and SiH_Four2SLM, C_ThreeH₈And 0.56 SLM, the amount of introduction was increased, and Ar was increased by 1 SLM and the amount of introduction was decreased. Then, the transition timing from the first step to the growth condition of the second step is the same as the SiH for 20 min immediately after the start of the transition, with the temperature of the growth crystal surface being immediately after the transition._FourAnd C_ThreeH₈Each of the conditions was gradually shifted by introducing 5 to 30 min and reducing the introduction of Ar to 20 to 40 min.
[0064]
At this time, in the first step, the flow rate of Ar serving as the atmospheric gas is 2 SLM, which is larger than the source gas, and the partial pressure is also increased. For this reason, the source gas reaching the surface of the growth crystal is controlled, and the stagnation of the unreacted gas on the surface of the growth crystal is prevented so that particles are not generated, and the generation of defects is suppressed. On the other hand, in the second step, since the raw material gas is increased and the atmospheric gas is decreased, the raw material supply speed is increased.
[0065]
When the grown crystal thus obtained was confirmed, it was confirmed that the growth rate in the second step was about 3 mm / h. Also, the dislocation density is a constant value of 2 × 10 from the early stage of growth to the late stage of growth.^FourPiece / cm²Met. Therefore, it can be said that the same growth as in Example 1 can be performed even if the raw material supply is directly performed with gas.
[Brief description of the drawings]
FIG. 1 is a diagram showing a cross-sectional configuration of a single crystal manufacturing apparatus used in a first embodiment of the present invention.
FIG. 2 is a diagram showing a cross-sectional configuration of a single crystal manufacturing apparatus used in a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Growth container, 2 ... SiC seed crystal, 3 ... SiC powder raw material, 4 ... Thermal insulation,
5 ... quartz reaction tube, 6 ... induction coil, 7 ... Ar introduction tube, 9 ... gas introduction tube.

Claims (16)

Production of a SiC single crystal in which a SiC single crystal is grown on the surface of the SiC seed crystal by disposing the SiC seed crystal (2) in the container (1) and supplying a raw material gas to the surface of the SiC seed crystal. In the method
A first step of growing on the surface of the SiC seed crystal so that a dislocation density of the SiC single crystal is 1 × 10 ⁵ pieces / mm ² or less;
After said first step, at a high growth rate than the first step, and have a second step of growing the SiC single crystal upper limit of the growth rate of 3 mm / h,
In the transition from the first step to the second step, the timing of shifting the temperature of the SiC single crystal surface from the first step condition to the second step condition determines the supply condition of the source gas. So as to be earlier than the timing for shifting from the condition of one process to the condition of the second process,
In the first step, by growing at a growth rate of 0.5 mm / h or less, the dislocation density at the initial growth stage of the SiC single crystal is 1 × 10 ⁵ pieces / mm ² or less,
A method for producing an SiC single crystal, wherein the first step is performed for 10 minutes or more . Production of a SiC single crystal in which a SiC single crystal is grown on the surface of the SiC seed crystal by disposing the SiC seed crystal (2) in the container (1) and supplying a raw material gas to the surface of the SiC seed crystal. In the method
On the surface of the SiC seed crystal, the dislocation density of the SiC single crystal is 1 × 10 ^Five Piece / mm ² A first step of growing so that:
After the first step, a second step of growing the SiC single crystal at a growth rate faster than the first step and setting the upper limit of the growth rate to 3 mm / h,
In the transition from the first step to the second step, the timing of shifting the temperature of the SiC single crystal surface from the first step condition to the second step condition determines the supply condition of the source gas. So as to be earlier than the timing for shifting from the condition of one process to the condition of the second process,
In the first step, by growing at a growth rate of 0.5 mm / h or less, the dislocation density at the initial growth stage of the SiC single crystal is 1 × 10 6. ^Five Piece / mm ² So that
The SiC single crystal manufacturing method, wherein the SiC single crystal is grown at least 100 μm or more by the first step. Wherein in the second step, the after the first step, SiC according to claim 1 or 2, characterized in the Turkey by increasing the growing crystal surface temperature than the first step to grow the SiC single crystal A method for producing a single crystal. Method for manufacturing a SiC single crystal according to any one of claims 1 to 3, characterized in that the first step in the initial growth of the SiC single crystal. Method for manufacturing a SiC single crystal according to any one of claims 1 to 4, characterized in that the growth rate more than five times the growth rate of the first step in the second step. The method for producing a SiC single crystal according to any one of claims 1 to 5 , wherein the temperature of the surface of the SiC single crystal in the second step is 2500 ° C or higher. According to any one of claims 1 to 6, characterized in that a high temperature 100 ° C. or higher than the temperature of the temperature said SiC single crystal surface in the first step of the SiC single crystal surface in the second step A method for producing a SiC single crystal. The SiC single crystal production according to any one of claims 1 to 7 , wherein a dislocation density of the SiC single crystal in the second step is 1 x 10 ⁵ pieces / cm ² or less. Method. As a method for supplying the raw material gas to the surface of the SiC seed crystal, a sublimation method for heating and sublimating a SiC powder raw material is used,
The method for producing a SiC single crystal according to any one of claims 1 to 8 , wherein a temperature of the SiC powder raw material in the second step is 2600 ° C or higher. As a method for supplying the raw material gas to the surface of the SiC seed crystal, a sublimation method for heating and sublimating a SiC powder raw material is used,
The temperature difference between the SiC powder raw material and the SiC single crystal surface in the first step is within 100 ° C.,
The SiC single crystal production according to any one of claims 1 to 9 , wherein a temperature difference between the SiC powder raw material and the surface of the SiC single crystal in the second step is 200 ° C or more. Method. The method for producing an SiC single crystal according to any one of claims 1 to 10 , wherein a growth rate of the SiC single crystal in the second step is set to 2.5 mm / h or more. The transition from the growth condition of the first step to the growth condition of the second step is performed over a period of 30 minutes or more when shifting from the first step to the second step. The method for producing a SiC single crystal according to any one of 11 . In the first step and the second step, an atmosphere gas is introduced together with the source gas,
In the first step, the partial pressure of the gas species used as the atmospheric gas is made larger than the partial pressure of the raw material gas, and in the second step, the partial pressure of the gas species used as the atmospheric gas is changed to the partial pressure of the raw material gas. The method for producing a SiC single crystal according to any one of claims 1 to 12 , wherein the SiC single crystal is made smaller. In the said 2nd process, at least 1 gas of hydrogen, oxygen, and chlorine is introduce | transduced as said atmospheric gas, The manufacturing method of the SiC single crystal as described in any one of the Claims 1 thru | or 13 characterized by the above-mentioned. Method for manufacturing a SiC single crystal according to any one of claims 1 to 14, wherein the use of crystals with as the SiC seed crystal, inclined from the c-plane surface. The SiC according to any one of claims 1 to 15 , wherein in the first step, the temperature of the surface of the SiC single crystal is set to 2400 ° C or lower, so that the SiC single crystal is 4H-SiC. A method for producing a single crystal.

Images