JP3776374B2 - Method for producing SiC single crystal and method for producing SiC wafer with epitaxial film - Google Patents

Description

[0001]
【Technical field】
  The present invention relates to a SiC single crystal containing almost no dislocations and defects in the crystal.ofManufacturing method and SiC wafer with epitaxial filmofIt relates to a manufacturing method.
[0002]
[Prior art]
Conventionally, SiC semiconductors using SiC single crystals are expected as candidate materials for next-generation power devices that replace Si semiconductors. In order to realize a high-performance SiC power device, it is essential to reduce the leakage current generated in the SiC semiconductor and to suppress the breakdown voltage. According to previous research reports, defects such as micropipe defects, spiral dislocations, edge dislocations, stacking faults, etc. occurring in the SiC single crystal are considered to cause leakage currents and breakdown voltage reduction of SiC semiconductors. It has been.
In addition, a SiC wafer having an epitaxial film is used for the power device. Therefore, it is desired to develop a SiC wafer with an epitaxial film that does not contain the above defects in the epitaxial film as well as in the SiC single crystal.
[0003]
As shown in FIG. 7, the SiC single crystal has {0001} plane (c plane) as main plane orientations, {1-100} plane (a plane) and {11-20} plane perpendicular to {0001} plane ( a side).
Conventionally, as a method for obtaining the SiC single crystal, first, an SiC seed crystal that exposes a hexagonal {0001} plane (c plane) or a plane within an offset angle of 10 ° from the {0001} plane as a seed crystal plane is used. Thus, a so-called c-plane growth method has been used in which a SiC single crystal is grown on a seed crystal surface by a sublimation reprecipitation method or the like.
[0004]
However, in the SiC bulk single crystal (c-plane grown crystal) grown in the <0001> direction with the {0001} plane as the seed crystal plane as described above, the micropipe defect is substantially parallel to the <0001> direction. , Spiral dislocation and edge dislocation 10 respectively⁰-10^Threecm^-2, 10^Three-10^Fourcm^-2, 10^Four-10^Fivecm^-2There was a problem of being included. Furthermore, when a SiC wafer is produced from this c-plane grown crystal and an epitaxial film is formed, defects and dislocations exposed on the surface of the SiC wafer are inherited in the epitaxial film. As a result, dislocations having substantially the same density as the SiC wafer exist in the epitaxial film, which has a problem of adversely affecting various device characteristics.
[0005]
On the other hand, in Japanese Patent Laid-Open No. 5-262599, a surface of a SiC single crystal whose inclination from the {0001} plane is 60 to 120 ° (preferably 90 °) is used as a seed crystal surface, and this seed crystal is grown in a-plane. Thus, a method for obtaining a growth crystal (a-plane growth crystal) is disclosed. And it was clarified that this a-plane grown crystal does not contain micropipe defects and screw dislocations.
[0006]
[Problems to be solved]
However, in the a-plane grown crystal, the stacking fault is in the {0001} plane and is approximately parallel to the growth direction.²-10^Fourcm^-1It is included at a high density. Further, edge dislocations having Burgers vectors parallel to and orthogonal to the <0001> direction are included in a high density substantially parallel to the growth direction. When an SiC wafer is formed from this a-plane grown crystal and an epitaxial film is formed, the dislocation and stacking fault are inherited from the high-density edge dislocations and stacking faults contained in the a-plane grown crystal in the epitaxial film. . As described above, the SiC single crystal and the SiC single crystal containing dislocations and stacking faults in a high density in the epitaxial film have a high on-resistance and a reverse leakage current, which may adversely affect the device operation. is there.
[0007]
  The present invention has been made in view of such conventional problems, and is a high-quality SiC single crystal containing almost no dislocations and defects.ofManufacturing method and SiC wafer with epitaxial film containing almost no defects and dislocations in SiC single crystal and epitaxial filmofProduction methodTheIt is something to be offered.
[0008]
[Means for solving problems]
  A first invention is a manufacturing method for manufacturing a bulk SiC single crystal by growing a SiC single crystal on a SiC seed crystal composed of a hexagonal SiC single crystal, wherein the manufacturing method is N times (N is N ≧ N ≧). 2), and each growth step is expressed as an nth growth step (n is a natural number and starts with 1 and ends with N).
  In the first growth step where n = 1, the angle of inclination from the {0001} plane60A first seed crystal having a face inclined by 90 ° to 90 ° exposed as a first growth face is produced, and a SiC single crystal is grown on the first growth face of the first seed crystal to produce a first growth crystal. And
  n = 2, 3,. . . , N in the continuous growth step, when the normal vector of the n-th growth surface is projected onto the {0001} plane and the direction of the vector is the n-th inclination direction, <0001 from the (n−1) -th inclination direction. > As the axis of rotation, and has an nth inclination direction when rotated by 45 ° to 135 °, and an inclination angle of 10 ° to 90 ° from the {0001} plane.(Except 10 °)The n-th seed crystal with the inclined surface exposed as the n-th growth surface is the n-th crystal (n−1) An n-th growth crystal is manufactured by growing a SiC single crystal on the n-th growth surface of the n-th seed crystal.And
  The nth growth step of the continuous growth step has at least one growth step in which the inclination angle between the nth growth surface and the {0001} plane is 60 ° to 90 °.(1) A method for producing a SiC single crystal.
[0009]
  Next, the effects of the present invention will be described.
  In the first growth step of the present invention, the inclination angle from the {0001} plane60 °A first seed crystal having a surface inclined by 90 ° exposed as a first growth surface is produced, and a SiC single crystal is grown on the first growth surface of the first seed crystal to produce a first growth crystal. .
  Therefore, there are many dislocations inherited mainly from the surface of the first growth surface in the first growth crystal. Here, the generation source of the dislocation is mainly a defect (dislocation, micropipe defect) exposed on the first growth surface. In the first growth step, most of the dislocation directions can be aligned substantially parallel to the first tilt direction, which is the vector direction obtained by projecting the normal vector of the first growth surface onto the {0001} plane.
[0010]
  Next, in the continuous growth step, the nth tilt direction is obtained when rotated from 45 ° to 135 ° about <0001> as the rotation axis from the (n−1) th tilt direction, and tilted from the {0001} plane. Angle 10 ° ~ 90 °(Except 10 °)The n-th seed crystal with the inclined surface exposed as the n-th growth surface is the n-th crystal (n−1) An n-th growth crystal is manufactured by growing a SiC single crystal on the n-th growth surface of the n-th seed crystal.The n-th growth step of the continuous growth step includes one or more growth steps in which the inclination angle between the n-th growth surface and the {0001} plane is 60 ° to 90 °.
  For this reason, dislocations existing in the (n-1) th grown crystal are hardly exposed on the nth growth surface. Most of the dislocations in the (n-1) th grown crystal exist in parallel to the (n-1) th tilt direction in the {0001} plane, and the dislocations are exposed to the nth growth surface.probabilityThis is because becomes smaller. Therefore, dislocations are hardly inherited from the n-th growth surface in the n-th growth crystal, and dislocations and defects are hardly generated.
  The continuous growth process can be performed once (when N = 2) and repeated a plurality of times. Each time the number of continuous growth steps is increased, the so-called dislocation density of the obtained grown crystal can be decreased exponentially.
[0011]
Thus, according to the present invention, it is possible to provide a method for producing a high-quality SiC single crystal that hardly contains micropipe defects, spiral dislocations, edge dislocations, and stacking faults.
[0013]
  Made according to the first inventionSiC single crystal,High quality with few micropipe defects, screw dislocations, edge dislocations, and stacking faults. Therefore, it can be used as a high-performance power device.
[0014]
  Next, the second invention is to produce a SiC wafer exposing a film formation surface from the SiC single crystal produced by the manufacturing method of the first invention, and to form an epitaxial film on the film formation surface of the SiC wafer. A method of manufacturing an SiC wafer with an epitaxial film, characterized in that the film is formed (claim).6).
[0015]
As described above, the SiC single crystal manufactured by the manufacturing method of the first invention has almost no micropipe defects, spiral dislocations, edge dislocations, and stacking faults, and has high quality. For this reason, the defects and dislocations are hardly exposed on the film-forming surface of the SiC wafer, and the dislocations are hardly inherited into the epitaxial film. Therefore, a SiC wafer with a high quality epitaxial film with few dislocations and defects can be produced.
[0017]
  Manufactured by the manufacturing method of the second invention.The SiC wafer with an epitaxial film is,The SiC single crystal and the epitaxial film contain almost no dislocations or defects. Therefore, it can be used for high-performance SiC electronic devices.
[0019]
  Using the above SiC wafer with an epitaxial filmThe SiC electronic device is,Low on-resistance and no leakage current.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
  In the first invention (invention 1), the inclination angle between the first growth surface and {0001} is60° to 90 °. When the angle is less than 1 °, the inclination angle is too small, and the n-th grown crystal is equivalent to a so-called c-plane grown crystal, and micropipe defects, spiral dislocations, edge dislocations, etc. occur at high density. .If the tilt angle is less than 60 °, dislocations that are not parallel to the tilt direction are exposed on the growth surface of the seed crystal in the next process, which may cause dislocations and defects in the grown crystal.
  Further, the nth tilt direction is at a position rotated from 45 ° to 135 ° about <0001> as a rotation axis from the (n−1) th tilt direction. When the angle is less than 45 °, the probability that the (n−1) th grown crystal is exposed to the nth growth surface is high, and even if the above continuous growth process is repeated, the dislocation contained in the nth grown crystal is hardly reduced. . Therefore, 60 degrees or more is more preferable. The same applies to cases where the angle exceeds 135 °, and more preferably 120 ° or less.
[0021]
The continuous growth step preferably includes one or more growth steps in which the n-th tilt direction is rotated 90 ° from the (n−1) -th tilt direction with <0001> as the rotation axis.
In this case, the probability that the dislocation is exposed on the nth growth surface becomes very small, and the possibility that dislocations and defects are generated in the nth growth crystal is reduced. As the number of growth steps is increased, the dislocation density in the grown crystal decreases.
[0022]
Moreover, before growing a SiC single crystal on each said growth surface, it is preferable to remove the deposit and work-affected layer on the surface of each growth surface.
In this case, it is possible to prevent dislocations inherited by each growth crystal from each growth surface caused by the deposits and the work-affected layer. Examples of methods for removing the deposits and the work-affected layer include polishing, chemical cleaning, reactive ion etching (RIE), sacrificial oxidation, and the like.
[0023]
Next, it is preferable that an inclination angle between the nth growth surface (n = 1, 2,..., N) and the {0001} plane is less than 70 °.
In this case, it is not necessary to grow the crystal highly, and the cost can be reduced. In the case of 70 ° or more, it is necessary to grow the crystal highly, which may increase the manufacturing cost.
[0024]
  Next, the inclination angle between the nth growth plane (n = 1, 2,..., N) and the {0001} plane is preferably 10 ° or more.
  In this case, penetrating defects such as micropipe defects, spiral dislocations, and edge dislocations can be reduced. If the angle is less than 10 °, these through defects may occur at a high density.
[0025]
  Next, n = N(However, excluding N = 2)In the Nth growth step, the inclination angle between the Nth growth surface and the {0001} plane is preferably 20 ° or less.
  In this case, the SiC single crystal finally grows in a substantially c-plane growth direction and becomes a so-called c-plane grown crystal that is widely used for device fabrication at present. Therefore, the SiC single crystal can be made effective for the production of SiC electronic devices.
[0026]
  next,In the n-th growth step of the above continuous growth stepThe growth process in which the inclination angle between the nth growth surface and the {0001} plane is 60 ° to 90 ° is performed once or more.
  In this case, dislocations in the crystal can be reduced efficiently.
  In general, when a crystal is grown on a growth surface having a tilt angle of 1 ° to 90 ° with respect to the {0001} plane, the direction of dislocations generated in the grown crystal often becomes substantially parallel to the tilt direction. When the inclination angle between the growth surface and the {0001} plane exceeds 60 °, almost all of the dislocations are substantially parallel to the inclination direction. Therefore, the nth growth plane and the {0001} planeInclination angleWhen the angle is set to 60 ° to 90 °, almost all dislocations can be made parallel to the tilt direction, and it becomes easy to hardly expose the dislocations on the growth surface of the seed crystal in the next step. .
  When the inclination angle between the n-th growth surface and the {0001} plane is less than 60 °, dislocations not parallel to the inclination direction are exposed on the growth surface of the seed crystal in the next process, and dislocations and defects are generated in the growth crystal. There is a fear.
[0027]
The growth process in which the inclination angle between the nth growth surface and the {0001} plane is 60 ° to 90 ° can be performed at least once, but after the dislocations in the crystal are sufficiently reduced. In the growth process, it is no longer necessary to increase the tilt angle, and a sufficiently high-quality crystal can be produced with good reproducibility even at a tilt angle as small as 1 to 20 °. In addition, if the inclination angle between the nth growth surface and the {0001} plane is reduced, it is not necessary to increase the height of the crystal, so that the cost can be reduced.
[0028]
  Sublimation reprecipitation is preferably used for the growth of the SiC single crystal on the various crystals.4)
  In this case, since a sufficient growth height can be obtained, a large-diameter SiC single crystal can be produced, and a high-quality SiC single crystal can be produced with good reproducibility and good productivity.
  The SiC single crystal growth technique that can be used in the present invention is not limited to the sublimation reprecipitation method, and any technique that can grow a bulk single crystal having a sufficient growth height can be applied. For example, Mater. Sci. Eng. B Vol. A chemical vapor deposition method in a temperature range exceeding 2000 ° C. as shown in 61-62 (1999) 113-120 can also be used.
[0029]
  The thickness of the various crystals is preferably 1 mm or more.5).
  In this case, it is possible to prevent dislocations and stacking faults that occur in the grown crystal due to the stress due to the difference in thermal expansion between the seed crystal and the object that fixes the seed crystal. That is, by sufficiently increasing the thickness of the seed crystal, it is possible to prevent the stress from distorting the lattice constituting the seed crystal and causing dislocations and stacking faults in the grown crystal. In particular, the area A of the seed crystal growth surface is 500 mm.²In the case of exceeding 1, the thickness of the seed crystal needs to be larger than 1 mm. If the minimum necessary thickness at this time is tseed, tseed = A^1/2The formula x2 / π is given. The seed crystal and the grown crystal are a concept including all seed crystals and all grown crystals in the present invention.
[0030]
  In the second invention, the film-forming surface is a surface having an offset angle of 0.5 ° to 20 ° from the {0001} surface, a surface having an offset angle of 20 ° or less from the {1-100} surface, or {11- 20} plane is preferably a plane having an offset angle of 20 ° or less.7).
  In this case, the occurrence of micropipe defects, spiral dislocations, and edge dislocations in the epitaxial film can be substantially suppressed. Note that, when a surface having an offset angle of less than 0.5 ° from the {0001} surface is used as the film formation surface, it may be difficult to form the epitaxial film.
[0031]
In addition, when the SiC wafer with an epitaxial film is manufactured using the surface having an offset angle of 20 ° or less from the {1-100} surface or the surface having an offset angle of 20 ° or less from the {11-20} surface as the film formation surface, The SiC wafer with an epitaxial film has a significantly reduced interface state generated at the interface between the oxide film and the SiC single crystal, and is effective in fabricating a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) device. It is. In addition, the surface whose offset angle is 20 ° or less from the {1-100} plane or the {11-20} plane is a concept including the {1-100} plane or the {11-20} plane, respectively.
[0032]
Here, {1-100}, {11-20}, and {0001} represent plane indices of so-called crystal planes. In the above surface index, the “-” symbol is usually added on the number, but in the present specification and drawings, it is added on the left side of the number for convenience of document preparation. Further, <0001>, <11-20>, and <1-100> represent directions in the crystal, and the handling of the “−” symbol is the same as the above-described plane index.
[0033]
The epitaxial film can be formed by CVD, PVE, or LPE. Here, the CVD method is a Chemical Vapor Deposition method, the PVE method is a Physical Vapor Epitaxy method, and the LPE method is a Liquid Phase Epitaxy (liquid phase epitaxy) method.
In this case, it is possible to easily control the film thickness and the impurity concentration in the film, which are design parameters important for device fabrication.
[0034]
In addition, 1 × 10¹³~ 1x10²⁰/ Cm^ThreeImpurities may be included.
In this case, the impurity serves as a donor, an acceptor, etc., and the SiC wafer with the epitaxial film can be used as a semiconductor device or the like. The impurity content is 1 × 10¹³/ Cm^ThreeIf it is less than the above, the impurities cannot supply a sufficient amount of carriers, and the device characteristics of the SiC wafer with an epitaxial film may be deteriorated. On the other hand, 1 × 10²⁰/ Cm^ThreeIn the case of exceeding the above, the impurities aggregate and as a result, dislocations and stacking faults may occur in the epitaxial film.
[0035]
Moreover, the said impurity can contain 1 or more types of nitrogen, boron, or aluminum as the structural element.
In this case, the epitaxial film can be a p-type or n-type semiconductor. Therefore, the SiC wafer with an epitaxial film can be used as a semiconductor device such as a diode and a transistor.
[0036]
【Example】
(Example 1)
An SiC single crystal and a method for manufacturing the same according to an embodiment of the present invention will be described.
The SiC single crystal manufacturing method of the present invention is a manufacturing method in which a SiC single crystal is grown on a SiC seed crystal composed of a hexagonal SiC single crystal as shown in FIGS. 1 to 5 to manufacture a bulk SiC single crystal. Is the method. The manufacturing method includes N growth steps (N = 2 in this example), and each growth step is represented as an nth growth step (n is a natural number and starts with 1 and ends with N).
[0037]
As shown in FIG. 1, in the first growth step where n = 1, the inclination angle α (α = 60 ° in this example) is inclined from the {0001} plane to the first inclination direction 153 which is the <11-20> direction. The first seed crystal 1 with the exposed surface exposed as the first growth surface 15 is produced. Then, as shown in FIG. 2, a SiC single crystal is grown on the first growth surface 15 of the first seed crystal 1 to produce the first growth crystal 10 (first growth step).
[0038]
Next, as shown in FIGS. 3 and 4, in the continuous growth process where n = 2, the direction of the vector obtained by projecting the normal vector 251 of the second growth surface 25 onto the {0001} plane is the second inclined direction 253. In this case, the first tilt direction 153 which is the <11-20> direction is rotated by β (β = 90 ° in this example) about <0001> as the rotation axis, that is, the second direction in the <1-100> direction. A second seed crystal 2 having a tilt direction 253 and exposing a plane tilted from the {0001} plane by a tilt angle γ (γ = 60 ° in this example) as the second growth plane 25 is formed from the first growth crystal 10. Make it. Then, as shown in FIG. 5, a SiC single crystal is grown on the second growth surface 25 of the second seed crystal 2 to produce a second growth crystal 20 to obtain a final SiC single crystal (continuous growth step). .
[0039]
Hereinafter, this example will be described in detail.
In this example, as shown in FIGS. 1 to 7, an SiC single crystal is manufactured by growing an SiC single crystal on a seed crystal made of an SiC single crystal by a sublimation reprecipitation method. This example is an example including N = 2, that is, two growth steps as described above.
[0040]
First, a SiC single crystal grown by a sublimation reprecipitation method was prepared. As shown in FIG. 7, the SiC single crystal has a {0001} plane, a {1-100} plane and a {11-20} plane perpendicular to the {0001} plane as main plane orientations. Further, the direction perpendicular to the {0001} plane is the <0001> direction, the direction perpendicular to the {1-100} plane is the <1-100> direction, and the direction perpendicular to the {11-20} plane is <11-20>. It is.
[0041]
As shown in FIG. 1, a surface inclined from the {0001} plane of the SiC single crystal by a tilt angle α (α = 60 °) in the first tilt direction 153 that is the <11-20> direction is exposed as the first growth surface 15. Thus, the SiC single crystal was cut, and the first growth surface 15 was further processed and polished. Further, the surface of the first growth surface 15 is chemically cleaned to remove deposits, and a work-affected layer associated with cutting / polishing is removed by RIE (Reactive Ion Etching) and sacrificial oxidation. It was. The thickness of the first seed crystal 1 is 2 mm.
[0042]
Next, as shown in FIG. 6, the first seed crystal 1 and the SiC raw material powder 75 were placed in the crucible 6 so as to face each other. At this time, the first seed crystal 1 was fixed to the inner surface of the lid 65 of the crucible 6 with an adhesive. And the said crucible 6 was heated at 2100-2400 degreeC in pressure reduction inert atmosphere. At this time, the temperature on the SiC raw material powder 75 side was set 20 to 200 ° C. higher than the temperature on the first seed crystal 1 side. Thereby, the SiC raw material powder 75 in the crucible 6 was sublimated by heating and deposited on the first seed crystal 1 having a temperature lower than that of the SiC raw material powder 75 to obtain the first growth crystal 10 (first growth step).
[0043]
As shown in FIG. 2, in the first grown crystal 10, there are many dislocations 105 having Burgers vectors parallel and orthogonal to the <0001> direction. The dislocation is a result of the defects exposed on the first growth surface 15 of the first seed crystal 1 being inherited in the first growth crystal 10. The direction of the dislocation 105 is almost all parallel to the first tilt direction 153.
[0044]
Next, as shown in FIG. 3 and FIG. 4, a rotation of> β (in this example, β = 90 °) from the first inclination direction 153 that is the <11-20> direction with <0001> as the rotation axis, that is, < A second seed crystal having a second inclined direction 253 in the 1-100> direction and exposing a plane inclined by an inclination angle γ (γ = 60 ° in this example) from the {0001} plane as the second growth plane 25 2 was prepared in the same manner as the first seed crystal 1. The thickness of the second seed crystal at this time was 2 mm.
[0045]
Next, as shown in FIG. 6, the second seed crystal 2 and the SiC raw material powder 75 were placed in the crucible 6 so as to face each other. At this time, the second seed crystal 2 was fixed to the inner surface of the lid body 65 of the crucible 6 with an adhesive. And the said crucible 6 was heated at 2100-2400 degreeC in pressure reduction inert atmosphere. At this time, the temperature on the SiC raw material powder 75 side was set 20 to 200 ° C. higher than the temperature on the second seed crystal 2 side. Thereby, the SiC raw material powder 75 in the crucible 6 was sublimated by heating and deposited on the second seed crystal 2 having a temperature lower than that of the SiC raw material powder 75 to obtain the second growth crystal 20 (continuous growth step).
As shown in FIG. 6, the second grown crystal 20 is obtained by growing a crystal on the second growth surface 25 in which almost no defects are exposed on the surface as described above. Therefore, dislocations and defects are hardly inherited in the second grown crystal 20, and the quality is high.
[0046]
Next, in order to investigate the defect density contained in the SiC single crystal produced as described above, the C-plane substrate produced from the SiC single crystal was subjected to KOH etching, and the number of etch pits generated thereby was measured. .
As a result, the number of etch pits corresponding to dislocations is 5 × 10.²~ 1x10^Three/ Cm²And very few.
[0047]
Hereinafter, the function and effect of this example will be described.
In the first growth step of this example, a first seed crystal 1 is produced in which a surface inclined from the {0001} plane by an inclination angle of 60 ° in the <11-20> direction is exposed as the first growth surface 15; A SiC single crystal is grown on the first growth surface 15 of the first seed crystal 1 to produce the first growth crystal 10.
For this reason, there are many dislocations 105 inherited from the surface of the first growth surface 15 in the first growth crystal 10, and most of the dislocations 105 in the direction of the normal vector 151 of the first growth surface 15. They can be aligned in a direction substantially parallel to the first tilt direction 153, which is the direction of the vector projected onto the {0001} plane.
[0048]
Next, in the second growth step, the second inclined direction 253, that is, the <1-100> direction is obtained by rotating 90 ° about the <0001> from the first inclined direction 153 that is the <11-20> direction. And the second seed crystal 2 having a surface inclined by 60 ° from the {0001} plane and exposed as the second growth surface 25 was produced in the same manner as the first seed crystal 1.
Therefore, when a surface inclined from the {0001} plane by an inclination angle of 60 ° from the {0001} plane is exposed as the second growth surface 25 in the second inclination direction 253 as described above, the surface of the second growth surface is exposed. Does not expose the dislocations present in the (n-1) th grown crystal. As described above, most of the dislocations 105 in the first growth crystal 10 exist in parallel to the first inclined direction 153 in the {0001} plane, and the probability that the dislocations 105 are exposed to the second growth surface 25. Because is small.
[0049]
Subsequently, the second seed crystal 2 is grown in the same manner as the first seed crystal, and a SiC single crystal is grown on the second growth surface 25 of the second seed crystal 2 as shown in FIG. A grown crystal 20 was produced to obtain a final SiC single crystal.
As described above, since dislocations and defects are hardly exposed on the surface of the second growth surface 25, dislocations are hardly inherited from the second growth surface 25 in the second growth crystal 10, and dislocations are not transferred. And there are few defects and it is of high quality.
[0050]
Further, in this example, before the SiC single crystal is grown on the first growth surface 15 and the second growth surface 25, the deposits and the work-affected layer are removed. Therefore, it is possible to prevent dislocations inherited from the respective growth surfaces 15 and 25 to the respective grown crystals 10 and 20 due to the deposits and the work-affected layer.
[0051]
Further, the thickness of the various crystals is set to 1 mm or more.
Therefore, it is possible to prevent dislocations and stacking faults generated in the grown crystals 10 and 20 due to the stress due to the difference in thermal expansion between the various crystals 1 and 2 and the lid 65 in contact with the seed crystal.
[0052]
Thus, according to the present example, it is possible to provide a high-quality SiC single crystal and a method for manufacturing the same, which hardly contain defects and dislocations.
[0053]
(Example 2)
In this example, an SiC single crystal is manufactured by changing the tilt angle γ in the second growth step of Example 1 to 90 °.
First, the same SiC single crystal as in Example 1 was prepared. A first seed crystal 1 was produced from this SiC single crystal in the same manner as in Example 1. The thickness of the first seed crystal 1 is 2 mm. Further, a first growth crystal 10 was obtained in the same manner as in Example 1 (first growth step).
[0054]
Next, as shown in FIG. 3 and FIG. 4, the first tilt direction 153 that is the <11-20> direction is rotated by β (β = 90 ° in this example) about <0001> as the rotation axis, that is, <1 A second seed crystal 2 having a second inclined direction 253 in the −100> direction and an exposed surface inclined by an inclination angle γ (γ = 90 ° in this example) from the {0001} plane as the second growth surface 25 Was prepared in the same manner as the first seed crystal 1. Then, the second seed crystal 2 is grown in the same manner as the first seed crystal, and a SiC single crystal is grown on the second growth surface 25 of the second seed crystal 2 as shown in FIG. A crystal 20 was produced to obtain a final SiC single crystal (continuous growth process).
Also in this example, as in Example 1, there were very few micropipe defects and dislocations, and a high-quality SiC single crystal could be obtained.
[0055]
(Example 3)
In this example, an example is shown in which a SiC single crystal is manufactured with the inclination angles α and γ in the first growth step and the second growth step of Example 1 both set to 90 °.
First, the same SiC single crystal as in Example 1 was prepared. Then, a surface inclined from the {0001} plane of the SiC single crystal by a tilt angle α (α = 90 °) in the first tilt direction 153 that is the <11-20> direction is exposed as the first growth surface 15. The SiC single crystal was cut, and the first growth surface 15 was further processed and polished. Similarly to Example 1, the surface of the first growth surface 15 is chemically cleaned to remove deposits, and the work-affected layer associated with cutting / polishing is removed by RIE (Reactive Ion Etching) and sacrificial oxidation. This was designated as first seed crystal 1. The thickness of the first seed crystal 1 is 2 mm. Subsequently, a first growth crystal 10 was obtained in the same manner as in Example 1 (first growth step).
[0056]
Next, as shown in FIG. 3 and FIG. 4, the first tilt direction 153 that is the <11-20> direction is rotated by β (β = 90 ° in this example) about <0001> as the rotation axis, that is, <1 A second seed crystal 2 having a second inclined direction 253 in the −100> direction and an exposed surface inclined by an inclination angle γ (γ = 90 ° in this example) from the {0001} plane as the second growth surface 25 Was prepared in the same manner as the first seed crystal 1. Then, the second seed crystal 2 is grown in the same manner as the first seed crystal, and a SiC single crystal is grown on the second growth surface 25 of the second seed crystal 2 as shown in FIG. A crystal 20 was produced to obtain a final SiC single crystal (continuous growth process).
Also in this example, as in Examples 1 and 2, there were very few micropipe defects and dislocations, and a high-quality SiC single crystal could be obtained.
[0057]
(Example 4)
In this example, N = 4, that is, an example in which the growth process is performed four times to produce a SiC single crystal.
First, the same SiC single crystal as in Example 1 was prepared.
In the first growth step, the inclination angle α (α = 90 in this example) from the SiC single crystal to the first inclination direction 153 that is the <11-20> direction from the SiC single crystal in the same manner as in Examples 1 to 3. °) A first seed crystal 1 having a tilted surface exposed as a first growth surface 15 is produced, and a SiC single crystal is grown on the first growth surface 15 of the first seed crystal 1 to thereby produce a first growth crystal 10. Got.
[0058]
Next, in the second growth step where n = 2, as in the first to third embodiments, β (in this example) the first inclination direction 153, which is the <11-20> direction, from <0001> as the rotation axis. β = 90 °), that is, the second inclined direction 253 in the <1-100> direction and the surface inclined by the inclination angle γ (γ = 90 ° in this example) from the {0001} plane is the second. The second seed crystal 2 exposed as the growth surface 25 is produced from the first growth crystal 10. Then, a SiC single crystal was grown on the second growth surface 25 of the second seed crystal 2 to obtain the first growth crystal 20.
[0059]
Next, in the third growth step where n = 3, the second tilt direction 153 which is the <1-100> direction is rotated by 90 ° about <0001> as the rotation axis, that is, in the <11-20> direction. A third seed crystal having a third tilt direction and exposing a plane inclined at an inclination angle of 3 ° from the {0001} plane as a third growth plane was produced in the same manner as the second seed crystal 2. The thickness of the third seed crystal at this time was 2 mm. Then, the third seed crystal was grown in the same manner as the first and second seed crystals to produce a third growth crystal.
The third grown crystal had high quality with very few micropipe defects and dislocations.
[0060]
Next, in the fourth growth step where n = 4, the film is rotated by 90 ° from the third tilt direction, which is the <11-20> direction, with <0001> as the rotation axis, that is, in the <1-100> direction. A fourth seed crystal having four tilt directions and exposing a plane inclined at an inclination angle of 3 ° from the {0001} plane as a fourth growth plane was prepared in the same manner as the third seed crystal. The thickness of the fourth seed crystal at this time was 2 mm. Then, the fourth seed crystal was grown in the same manner as the first to third seed crystals to produce a fourth growth crystal.
The fourth growth crystal had very few micropipe defects, dislocations, etc., and was as high as or better than the third growth crystal.
[0061]
(Example 5)
In this example, an example of producing an SiC wafer with an epitaxial film is shown.
As shown in FIG. 8, the manufacturing method of the SiC wafer 4 with an epitaxial film in this example produces an SiC wafer 3 that exposes a film formation surface 35 from an SiC single crystal, and the SiC wafer 3 is formed on the film formation surface 35 of the SiC wafer 3. An epitaxial film 30 is formed.
[0062]
First, the high-quality SiC single crystal 20 obtained in Example 3 was prepared. Three types of SiC, in which a surface inclined by 5 ° from the {0001} plane of the SiC single crystal 20 in the <11-20> direction, a {1-100} plane, and a {11-20} plane are exposed as film formation planes A wafer was produced. The SiC wafer was subjected to surface treatment such as processing, polishing, chemical cleaning, RIE, sacrificial oxidation, and the like, similar to the production of the first seed crystal in Example 1 above.
[0063]
Then, as shown in FIG. 8, the epitaxial film 30 was formed on the film formation surface 35 of the SiC wafer 3 by chemical vapor deposition, and the SiC wafer 4 with the epitaxial film was manufactured. Specifically, SiH as the source gas_FourGas and C_ThreeH₈Gas at 5 ml / min and H as carrier gas₂Gas was introduced into the reaction tube at a rate of 10 liters / minute, and film formation was performed with the temperature of the susceptor holding the SiC wafer being 1550 ° C. and the atmospheric pressure being 10 kPa.
[0064]
The defect density of micropipe defects, dislocations, inclusions, etc. in the epitaxial film 30 in this example was very small, and a high-quality SiC wafer 4 with an epitaxial film could be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the plane orientation of a first growth surface according to Examples 1 to 5. FIG.
FIG. 2 is an explanatory diagram showing the growth direction and dislocation direction of a first growth crystal according to Examples 1 to 5.
FIG. 3 is an explanatory diagram showing a relationship between a first inclination direction and a second inclination direction according to Examples 1 to 5;
FIG. 4 is an explanatory diagram showing a plane orientation of a second growth surface according to Examples 1 to 5.
FIG. 5 is an explanatory diagram showing the growth direction of a second growth crystal according to Examples 1 to 5.
FIG. 6 is an explanatory view showing a method for growing a SiC single crystal by sublimation reprecipitation method according to Examples 1 to 5.
7 is an explanatory diagram showing main plane orientations of a SiC single crystal according to Example 1. FIG.
8 is an explanatory diagram of an SiC wafer with an epitaxial film according to Example 5. FIG.
[Explanation of symbols]
1. . . First crystal,
15. . . First growth surface,
151. . . Normal vector (first growth step),
153. . . First tilt direction,
10. . . First grown crystal,
2. . . The second seed crystal,
25. . . Second growth surface,
251. . . Normal vector (second growth process),
253. . . Second tilt direction,
20. . . Second grown crystal,
3. . . SiC wafer,
35. . . Deposition surface,
30. . . Epitaxial film,
4). . . SiC wafer with epitaxial film,

Claims (7)

In a manufacturing method for manufacturing a bulk SiC single crystal by growing a SiC single crystal on a SiC seed crystal composed of a hexagonal SiC single crystal, the manufacturing method is N times (N is a natural number of N ≧ 2). When each growth process is represented as an nth growth process (n is a natural number and starts with 1 and ends with N),
In the first growth step where n = 1, a first seed crystal is produced by exposing a surface inclined at an inclination angle of 60 ° to 90 ° from the {0001} plane as the first growth surface. A SiC single crystal is grown on the first growth surface of the first to produce a first growth crystal,
n = 2, 3,. . . , N in the continuous growth step, when the normal vector of the n-th growth surface is projected onto the {0001} plane and the direction of the vector is the n-th inclination direction, <0001 from the (n−1) -th inclination direction. > Is the nth growth direction with the nth inclination direction at 45 ° to 135 ° rotation and the inclination angle of 10 ° to 90 ° (excluding 10 °) from the {0001} plane. An n-th seed crystal exposed as a surface is produced from an (n - 1) -th growth crystal, and a SiC single crystal is grown on the n-th growth surface of the n-th seed crystal to produce an n-th growth crystal ;
In the n-th growth step of the continuous growth step, the SiC single crystal is characterized by having at least one growth step in which the inclination angle between the n-th growth surface and the {0001} plane is 60 ° to 90 ° . Production method.   2. The method for producing a SiC single crystal according to claim 1, wherein an inclination angle between the n-th growth surface (n = 1, 2,..., N) and a {0001} plane is less than 70 °. . 2. The N-th growth step in which n = N (excluding N = 2) according to claim 1, wherein an inclination angle between the N-th growth surface and the {0001} plane is 20 ° or less. A method for producing a SiC single crystal. The method for producing a SiC single crystal according to any one of claims 1 to 3, wherein a sublimation reprecipitation method is used for the growth of the SiC single crystal on the various crystals . The method for producing a SiC single crystal according to any one of claims 1 to 4, wherein the thickness of each of the various crystals is 1 mm or more . An SiC wafer in which a film formation surface is exposed from the SiC single crystal produced by the manufacturing method according to claim 3 is produced, and an epitaxial film is formed on the film formation surface of the SiC wafer. Manufacturing method of SiC wafer with film . 7. The film formation surface according to claim 6, wherein the film formation surface is a surface having an offset angle of 0.5 ° to 20 ° from the {0001} surface, a surface having an offset angle of 20 ° or less from the {1-100} surface, or a {11-20} surface. A method for producing a SiC wafer with an epitaxial film, characterized in that the surface has an offset angle of 20 ° or less .

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