JP2003321298A - SiC SINGLE CRYSTAL AND METHOD FOR PRODUCING THE SAME, SiC WAFER WITH EPITAXIAL FILM AND METHOD FOR PRODUCING THE SAME, AND SiC ELECTRONIC DEVICE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a high-quality SiC single crystal containing substantially no dislocation and defects and to provide a method for producing the same; to obtain an SiC wafer with an epitaxial film containing substantially no defects and dislocation in the epitaxial film and to provide a method for producing the same; and to provide an SiC device showing substantially no occurrence of leak current and reduction of withstand voltage. <P>SOLUTION: A first seed crystal is prepared in which the plane inclined 1°-90° from the [0001] plane is exposed as a first growing plane. An n-th seed crystal is prepared which has an n-th inclined direction at a location 45°-135° rotated from an (n-1)-th inclined direction about <0001> as a rotation axis and in which the plane inclined 1°-90° from the [0001] plane is exposed as an n-th growing plane. An n-th growing crystal is prepared by growing the SiC single crystal on the n-th growing plane of the n-th seed crystal. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an SiC single crystal containing almost no dislocations and defects in the crystal, a method for producing the same, an SiC wafer with an epitaxial film and a method for producing the same, and Si using the SiC wafer with the epitaxial film.
C electronic device.

[0002]

2. Description of the Related Art Conventionally, SiC using a SiC single crystal
Semiconductors are expected as candidate materials for next-generation power devices to replace Si semiconductors. In order to realize a high-performance SiC power device, it is indispensable to reduce the leak current generated in the SiC semiconductor and to suppress the breakdown voltage reduction. According to previous research reports,
It is considered that defects such as micropipe defects, screw dislocations, edge dislocations, and stacking faults that occur in the above-mentioned SiC single crystal are the cause of leakage current and reduction of breakdown voltage of the SiC semiconductor. In addition, a SiC wafer having an epitaxial film is used for the purpose of the power device. Therefore, it is desired to develop a SiC wafer with an epitaxial film that does not contain the above defects not only in the SiC single crystal but also in the epitaxial film.

As shown in FIG. 7, a SiC single crystal has a {0001} plane (c-plane) and a {0001} plane as major plane orientations.
{1-100} plane (a plane) perpendicular to the plane and {11-2
0} surface (a surface). As a conventional method for obtaining the above-mentioned SiC single crystal, first, hexagonal {0001}
Offset angle 10 from plane (c-plane) or {0001} plane
A method of performing so-called c-plane growth has been used, in which a SiC single crystal is exposed by using a SiC seed crystal whose surface within ° is exposed as a seed crystal surface, and a SiC single crystal is grown on the seed crystal surface by a sublimation reprecipitation method.

However, as described above, the {0001} plane is seeded.
SiC formed as a crystal plane and grown in the <0001> direction
In the bulk single crystal (c-plane grown crystal), the <0001> direction
Micropipe defects, screw dislocations, and edge dislocations that are substantially parallel to the direction
10 each⁰-10³cm ^-2, 10³-10^Fourcm^-2，
10^Four-10^Fivecm^-2There was a problem that it was included to some extent.
Furthermore, a SiC wafer was prepared from this c-plane grown crystal.
When an epitaxial film is formed,
Inherits defects and dislocations exposed on the surface of the SiC wafer
To be done. This allows Si in the epitaxial film as well.
There are dislocations of approximately the same density as the C wafer, and various device characteristics
There was a problem that it adversely affected the.

On the other hand, in Japanese Unexamined Patent Publication No. 262599/1993, the inclination of the SiC single crystal from the {0001} plane is 60 to
The plane of 120 ° (preferably 90 °) is used as the seed crystal plane,
A method of growing a seed crystal by a-plane growth to obtain a grown crystal (a-plane grown crystal) is disclosed. It was also clarified that the a-plane grown crystal does not contain micropipe defects or screw dislocations.

[0006]

However, in the a-plane grown crystal, stacking faults are contained in the {0001} plane at a high density of 10 ² to 10 ⁴ cm ^-1 substantially parallel to the growth direction. In addition, edge dislocations having Burgers vectors parallel and orthogonal to the <0001> direction are included at a high density in a direction substantially parallel to the growth direction. When a SiC wafer is prepared from this a-plane grown crystal and an epitaxial film is formed, the dislocations and stacking faults are inherited from the high density edge dislocations and stacking faults contained in the a-plane grown crystal in the epitaxial film. . Thus, the SiC single crystal and the SiC single crystal containing dislocations and stacking faults in the epitaxial film at a high density have a high on-resistance and a reverse leakage current.
May adversely affect device operation.

The present invention has been made in view of the above conventional problems, and is a high-quality SiC single crystal containing few dislocations and defects, a method for manufacturing the same, and defects and dislocations in the SiC single crystal and the epitaxial film. It is intended to provide a SiC wafer with an epitaxial film containing almost no hydrogen, a method for manufacturing the same, and a SiC electronic device with almost no occurrence of leak current and reduction in breakdown voltage.

[0008]

According to a first aspect of the present invention, there is provided a manufacturing method for producing a bulk SiC single crystal by growing a SiC single crystal on a SiC seed crystal made of a hexagonal SiC single crystal.
The manufacturing method includes N times of growth steps (N is a natural number of N ≧ 2), and each growth step is represented by an n-th growth step (n is a natural number and an ordinal number starting from 1 and ending with N). =
In the first growth step of No. 1, a first seed crystal in which a surface inclined at an inclination angle of 1 ° to 90 ° from the {0001} plane is exposed as a first growth surface is prepared, and First
A SiC single crystal is grown on the growth surface to prepare a first grown crystal, and n = 2, 3 ,. ． ． , N in the continuous growth step, if the direction of the vector obtained by projecting the normal vector of the n-th growth surface onto the {0001} plane is the n-th tilt direction, then from the (n-1) -th tilt direction, <0001 > As the axis of rotation 4
It has the n-th tilt direction at the position rotated by 5 ° to 135 °,
An n-th seed crystal in which a surface inclined at an inclination angle of 1 ° to 90 ° from the {0001} plane is exposed as the n-th growth surface is prepared from the (n-1) -th grown crystal, and A method for producing a SiC single crystal is characterized in that a SiC single crystal is grown on an nth growth surface to produce an nth growth crystal (claim 1).

Next, the function and effect of the present invention will be described.
In the first growth step of the present invention, a first seed crystal in which a surface inclined at an inclination angle of 1 ° to 90 ° from the {0001} plane is exposed as a first growth surface is prepared, and the first seed crystal of the first seed crystal is formed. A SiC single crystal is grown on the first growth surface to prepare a first grown crystal. Therefore, a large number of dislocations inherited mainly from the surface of the first growth surface are present in the first growth crystal. Here, the generation sources of the dislocations are mainly the defects (dislocations and micropipe defects) 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 direction of the vector obtained by projecting the normal vector of the first growth surface onto the {0001} plane.

Next, in the above continuous growth step, from the (n-1) th tilt direction, <0001>
It has the n-th tilt direction at the position rotated by 5 ° to 135 °,
An n-th seed crystal in which a surface inclined at an inclination angle of 1 ° to 90 ° from the {0001} plane is exposed as the n-th growth surface is prepared from the (n-1) -th grown crystal, and A SiC single crystal is grown on the nth growth surface to produce an nth growth crystal. Therefore, dislocations existing in the (n-1) th grown crystal are hardly exposed on the nth growth surface. The (n
-1) Most of the dislocations in the grown crystal are parallel to the (n-1) th tilt direction in the {0001} plane, and the probability of exposing the dislocations to the nth growth plane is small. is there.
Therefore, dislocations are hardly inherited from the n-th growth surface in the n-th growth crystal, and dislocations and defects are hardly generated. In addition, the continuous growth step is performed once (N =
2) or repeated several times.
The so-called dislocation density of the obtained grown crystal can be exponentially decreased each time the number of continuous growth steps is increased.

As described above, according to the present invention, it is possible to provide a method for producing a high-quality SiC single crystal which hardly contains micropipe defects, screw dislocations, edge dislocations, and stacking faults.

Next, a second invention is a SiC single crystal produced by the manufacturing method of the first invention (claim 8).

The SiC single crystal of the present invention is manufactured by the manufacturing method of the first invention. for that reason,
The SiC single crystal has micropipe defects, screw dislocations,
High quality with almost no edge dislocations and stacking faults. Therefore, it can be used as a high performance power device.

Next, a third aspect of the present invention is to manufacture an SiC wafer having a film-forming surface exposed from the SiC single crystal produced by the manufacturing method of the first invention, and epitaxially deposit the SiC wafer on the film-forming surface. A method for manufacturing a SiC wafer with an epitaxial film is characterized in that a film is formed (claim 9).

S manufactured by the manufacturing method of the first invention
As described above, the iC single crystal is of high quality, containing almost no micropipe defects, screw dislocations, edge dislocations, and stacking faults. Therefore, the defects and dislocations are barely exposed on the film formation surface of the SiC wafer, and dislocations are hardly inherited in the epitaxial film. Therefore,
S with high quality epitaxial film with few dislocations and defects
An iC wafer can be produced.

Next, a fourth invention is an SiC wafer with an epitaxial film, which is manufactured by the manufacturing method of the third invention (claim 11).

The SiC wafer with the epitaxial film is manufactured by the manufacturing method of the third invention. Therefore, the SiC wafer with the epitaxial film is
Almost no dislocations or defects are contained in the single crystal and the epitaxial film. Therefore, it can be used for a high-performance SiC electronic device.

Next, a fifth invention is a SiC electronic device characterized by using the SiC wafer with an epitaxial film of the fourth invention (claim 12).

The SiC electronic device of the present invention uses the SiC wafer with the epitaxial film of the fourth invention,
As described above, the SiC wafer with the epitaxial film has high quality with few dislocations and defects. Therefore, the above-mentioned SiC electronic device has a low on-resistance and is excellent in that no leak current occurs.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION In the first invention (claim 1), the inclination angle between the first growth surface and {0001} is 1 ° to 90 °. If it is less than 1 °, the tilt angle is too small, and the n-th grown crystal becomes equivalent to a so-called c-plane grown crystal, and micropipe defects, screw dislocations, edge dislocations, etc. occur at high density. . Also, the n-th tilt direction is <0001> from the (n-1) -th tilt direction.
Is about 45 ° to 135 ° about the rotation axis. When the angle is less than 45 °, the probability that the (n-1) th growth crystal is exposed to the nth growth surface is high, and even if the above continuous growth step is repeated, the dislocations contained in the nth growth crystal are hardly reduced. . Therefore, it is more preferably 60 ° or more. The same applies when the angle exceeds 135 °, more preferably 120 ° or less.

In the continuous growth step, the n-th tilt direction is the (n-th) axis with <0001> as the rotation axis.
1) It is preferable to include at least one growth step in which the film is rotated by 90 ° from the tilt direction. In this case, the probability of dislocations being exposed on the n-th growth surface is very small, and the possibility of dislocations and defects occurring in the n-th growth crystal is reduced. The dislocation density in the grown crystal decreases as the number of growth steps increases.

Before growing the SiC single crystal on each growth surface, it is preferable to remove the deposits and work-affected layers on the surface of each growth surface. In this case, it is possible to prevent dislocations that are inherited by the grown crystals from the growth surfaces due to the deposits and work-affected layers. As a method for removing the above-mentioned deposits and work-affected layers, for example, polishing,
Chemical cleaning, Reactive Ion Etching
(RIE), sacrificial oxidation, etc.

Next, the nth growth surface (n = 1,
2 ,. ． ． , N) and the tilt angle between the {0001} plane is 7
It is preferably less than 0 ° (claim 2). In this case, it is not necessary to grow the crystal high, and the cost can be reduced. In the case of 70 ° or more, it is necessary to grow the crystal high, which may increase the manufacturing cost.

Next, the n-th growth surface (n = 1,
2 ,. ． ． , N) and the tilt angle between the {0001} plane is 1
It is preferably 0 ° or more (claim 3). In this case, threading defects such as micropipe defects, screw dislocations and edge dislocations can be reduced. If it is less than 10 °, these penetrating defects may occur at a high density.

Next, in the Nth growth step where n = N, the inclination angle between the Nth growth surface and the {0001} plane is 2
It is preferably 0 ° or less (claim 4). In this case, the SiC single crystal finally grows in the substantially c-plane growth direction, and is widely used at present for device fabrication.
This is a so-called c-plane grown crystal. Therefore, the above-mentioned SiC single crystal can be made effective in producing a SiC electronic device.

Next, in the nth growth step (where n ≠ N), at least one growth step in which the inclination angle between the nth growth surface and the {0001} plane is 60 ° to 90 ° is performed. Is preferred (Claim 5). In this case, dislocations in the crystal can be efficiently reduced. Generally, {0001}
When a crystal is grown on a growth surface having an inclination angle of 1 ° to 90 ° with respect to the plane, the direction of dislocation generated in the grown crystal is almost parallel to the inclination direction in many cases. This growth surface and {000
When the tilt angle with respect to the 1} plane exceeds 60 °, almost all of the dislocations are substantially parallel to the tilt direction. Therefore, the above nth
Inclination angle between growth plane and {0001} plane is 60 °
When it is set to 90 °, almost all dislocations can be made parallel to the tilt direction, and it becomes easy to prevent dislocations from being barely exposed on the growth surface of the seed crystal in the next step. When the tilt angle between the n-th growth plane and the {0001} plane is less than 60 °, dislocations not parallel to the tilt direction are exposed on the growth surface of the seed crystal in the next step, causing dislocations or defects in the grown crystal. There is a risk.

The growth step in which the inclination angle between the n-th growth plane and the {0001} plane is 60 ° to 90 ° can be performed at least once, but dislocations in the crystal are sufficiently reduced. In the subsequent growth step, it is no longer necessary to increase the tilt angle, and a sufficiently high quality crystal can be produced with good reproducibility even with a small tilt angle of, for example, 1 to 20 °. In addition, the above nth growth plane and {0001}
If the tilt angle with respect to the plane is reduced, it is not necessary to increase the height of the crystal, and the cost can be reduced.

It is preferable to use the sublimation reprecipitation method for growing the SiC single crystal on the above various crystals (Claim 6). In this case, since a sufficient growth height can be obtained, S having a large diameter is used.
It is possible to manufacture an iC single crystal, and it is possible to manufacture a high-quality SiC single crystal with good reproducibility and productivity. The SiC single crystal growth method that can be used in the present invention is not limited to the sublimation reprecipitation method, and any method that can grow a bulk single crystal with a sufficient growth height can be applied. For example, Mater. Sci. Eng. B V
ol. 61-62 (1999) 113-120, the chemical vapor deposition method in the temperature range over 2000 degreeC can also be used.

The thickness of each of the various crystals is preferably 1 mm or more (claim 7). 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 fixing 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. Further, especially when the area A of the growth surface of the seed crystal exceeds 500 mm ² , the thickness of the seed crystal needs to be made larger than 1 mm. If the minimum necessary thickness at this time is tseed, then tsee
The formula of d = A ^1/2 × 2 / π is given. The seed crystal and the grown crystal are concepts including all seed crystals and all grown crystals in the present invention.

In the third invention, the film-forming surface has an offset angle of 0.5 ° to 20 ° from the {0001} surface.
Plane of 0 °, a plane with an offset angle of 20 ° or less from the {1-100} plane, or a plane of 20 ° from the {11-20} plane
It is preferably a surface of not more than ° (claim 10). In this case, generation of micropipe defects, screw dislocations and edge dislocations in the epitaxial film can be almost suppressed. In addition, when the face having an offset angle of less than 0.5 ° from the {0001} face is used as a film-forming face, it may be difficult to form the epitaxial film.

Further, the SiC wafer with the epitaxial film was prepared by using the surface having an offset angle of 20 ° or less from the {1-100} plane or the surface having an offset angle of 20 ° or less from the {11-20} plane as the film formation surface. In this case, the SiC wafer with the epitaxial film is
The interface state generated at the interface with the single crystal is significantly reduced, and MOSFET (Metal-Oxide-Semiconductor Field)
Effect Transistor) This is effective in manufacturing devices. It should be noted that the planes having an offset angle of 20 ° or less from the {1-100} plane or the {11-20} plane are {1-
This is a concept including the 100} plane or the {11-20} plane.

Here, {1-100}, {11-20}
And {0001} represent so-called crystal plane index. In the above surface index, the "-" symbol is usually added above the number, but in this specification and the drawings, it is added to the left side of the number for convenience of document preparation. Also, <0001
>, <11-20>, and <1-100> represent directions in the crystal, and the handling of the “−” symbol is the same as the above-mentioned plane index.

Further, in forming the epitaxial film,
A CVD method, a PVE method, or an LPE method can be used. Here, the above-mentioned CVD method is a chemical vapor
or Deposition (Chemical Vapor Deposition) method, the PVE method is Physical Vapor Epit
The axy (sublimation epitaxy) method, the LPE method is Li
It refers to a liquid phase epitaxy method. In this case, the film thickness and the impurity concentration in the film, which are important design parameters in device fabrication, can be easily controlled.

Further, 1 × 10 ^{13 is formed on the} above epitaxial film.
Impurities of up to 1 × 10 ²⁰ / cm ³ can be included. In this case, the impurities play a role of donors or acceptors, and the SiC wafer with the epitaxial film can be used as a semiconductor device or the like. When the content of the above impurities is less than 1 × 10 ¹³ / cm ³ ,
The impurities cannot supply a sufficient amount of carriers, and the device characteristics of the SiC wafer with the epitaxial film may deteriorate. On the other hand, 1 × 10 ²⁰ / cm
If it exceeds ³ , the impurities may aggregate, and as a result, dislocations or stacking faults may occur in the epitaxial film.

Further, the above-mentioned impurities are constituent elements thereof,
It may contain one or more of nitrogen, boron or aluminum. In this case, the epitaxial film is
Alternatively, it can be an n-type semiconductor. Therefore, the SiC wafer with the epitaxial film can be used as a semiconductor device such as a diode and a transistor.

[0036]

EXAMPLES Example 1 SiC according to an example of the present invention
The single crystal and the manufacturing method thereof will be described. Si of the present invention
As shown in FIGS. 1 to 5, the method for producing a C single crystal is a method for producing a bulk SiC single crystal by growing the SiC single crystal on a SiC seed crystal made of a hexagonal SiC single crystal. . The manufacturing method includes N times (N = 2 in this example) of growth steps, and each growth step is represented as an nth growth step (n is a natural number and an ordinal number starting from 1 and ending with N).

As shown in FIG. 1, in the first growth step with n = 1, the inclination angle α (α in this example, from the {0001} plane to the first inclination direction 153, which is the <11-20> direction.
= 60 °) The first seed crystal 1 in which the tilted surface is 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 a first grown crystal 10 (first growing step).

Next, as shown in FIGS. 3 and 4, n = 2
In the continuous growth step of <11-20, when 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 tilt direction 253, <11-20
When rotated by β (β = 90 ° in this example) from the first inclination direction 153, which is the> direction, with <0001> as the rotation axis,
That is, having a second tilt direction 253 in the <1-100> direction,
And the inclination angle γ from the {0001} plane (γ = 60 in this example)
°) The second seed crystal 2 in which the inclined surface is exposed as the second growth surface 25 is produced from the first growth crystal 10. And FIG.
As shown in (1), a SiC single crystal is grown on the second growth surface 25 of the second seed crystal 2 to produce a second grown crystal 20, which is a final SiC single crystal (continuous growth step).

Hereinafter, this example will be described in detail. In this example, as shown in FIGS. 1 to 7, a SiC single crystal is grown on a seed crystal made of a SiC single crystal by a sublimation reprecipitation method to produce a SiC single crystal. Further, this example is an example including N = 2, that is, two growth steps as described above.

First, SiC grown by the sublimation reprecipitation method
A single crystal was prepared. As shown in FIG. 7, the SiC single crystal has {0001} planes and {000} planes as main plane orientations.
It has a {1-100} plane and a {11-20} plane perpendicular to the 1} plane. In addition, the direction perpendicular to the {0001} plane is the <0001> direction, and the direction perpendicular to the {1-100} plane is the <0001> direction.
1-100> direction, the direction perpendicular to the {11-20} plane is <
11-20>.

As shown in FIG. 1, a surface inclined by an inclination angle α (α = 60 °) from the {0001} plane of the SiC single crystal in the first inclination direction 153 which is the <11-20> direction is first
The SiC single crystal was cut so as to be exposed as the growth surface 15, 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 RIE (Reactive Ion Etchin) is performed.
g) By sacrificial oxidation, the work-affected layer due to cutting and polishing was removed, and this was designated as the first seed crystal 1. The thickness of the first seed crystal 1 is 2 mm.

Next, as shown in FIG. 6, the first seed crystal 1 and the SiC raw material powder 75 were placed in the crucible 6 such that they 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. Then, the crucible 6 is set to 2100 to 240 in a reduced pressure inert atmosphere.
Heated to 0 ° C. At this time, the temperature of the SiC raw material powder 75 side was set to 20 to 200 ° C. higher than the temperature of the first seed crystal 1 side. As a result, the SiC raw material powder 75 in the crucible 6 is sublimated by heating, and the first raw material at a temperature lower than that of the SiC raw material powder 75
A first grown crystal 10 was obtained by depositing on the seed crystal 1 (first growing step).

As shown in FIG. 2, 1 in the first grown crystal
At 0, there are many dislocations 105 having Burgers vectors parallel and orthogonal to the <0001> direction. The dislocations are caused as 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. Almost all of the dislocations 105 are parallel to the first tilt direction 153.

Next, as shown in FIGS. 3 and 4, <11
From the first tilt direction 153, which is the −20> direction, to <0001
When> β (β = 90 ° in this example) is rotated about> as the rotation axis, that is, the second tilt direction 253 in the <1-100> direction.
And a second seed crystal 2 exposed as a second growth surface 25 having a tilt angle γ (γ = 60 ° in this example) from the {0001} plane as in the first seed crystal 1. It was made.
The thickness of the second seed crystal at this time was 2 mm.

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 that they face each other. At this time, the second seed crystal 2 was fixed to the inner surface of the lid 65 of the crucible 6 via an adhesive. Then, the crucible 6 is set to 2100-24 in a reduced pressure inert atmosphere.
Heated to 00 ° C. At this time, the temperature of the SiC raw material powder 75 side was set to 20 to 200 ° C. higher than the temperature of the second seed crystal 2 side. As a result, the SiC raw material powder 75 in the crucible 6 was sublimated by heating and deposited on the second seed crystal 2 at a temperature lower than that of the SiC raw material powder 75 to obtain the second grown crystal 20 (continuous growth step). As shown in FIG. 6, the second grown crystal 20
Is the second growth surface 2 with almost no defects exposed on the surface.
The crystal was grown on the No. 5 as described above.
Therefore, dislocations and defects were hardly inherited in the second grown crystal 20, and the quality was high.

Next, in order to investigate the defect density contained in the SiC single crystal produced as described above, the above SiC
The C-plane substrate made of a single crystal was subjected to KOH etching, and the number of etch pits generated by this was measured. As a result, the number of etch pits corresponding to dislocations is 5 × 10 ^2.
It was 1 × 10 ³ / cm ² , which was very small.

The operation and effect of this example will be described below. In the first growth step of this example, from the {0001} plane,
11-20> The first seed crystal 1 in which a surface inclined at an inclination angle of 60 ° is exposed as the first growth surface 15 is prepared, and a SiC single crystal is formed on the first growth surface 15 of the first seed crystal 1. The crystal is grown to produce the first grown crystal 10. Therefore, a large number of dislocations 105 inherited from the surface of the first growth surface 15 exist in the first growth crystal 10, but most of the dislocations 105 in the direction of the dislocations 105 are defined by the normal vector 151 of the first growth surface 15. It is possible to align in a direction substantially parallel to the first tilt direction 153, which is the direction of the vector projected on the {0001} plane.

Next, in the second growth step, <11-
20> direction from the first tilt direction 153 to <0001>
The second tilt direction 2
53, ie, <1-100> direction, and {000
A second seed crystal 2 in which a surface inclined at an inclination angle of 60 ° from the 1} plane was exposed as a second growth surface 25 was prepared in the same manner as the first seed crystal 1. Therefore, as described above, the first grown crystal 10
When a surface inclined at an inclination angle of 60 ° from the {0001} plane in the second inclination direction 253 is exposed as the second growth surface 25, the surface of this second growth surface is Almost no dislocations existing in are exposed. As described above, most of the dislocations 105 in the first grown crystal 10 exist in parallel to the first tilt direction 153 in the {0001} plane, and the probability that the dislocations 105 are exposed on the second growth surface 25. Because is small.

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. Then, the second grown crystal 20 was produced to be a final SiC single crystal. As described above, since the dislocations and defects are barely exposed on the surface of the second growth surface 25, the dislocations are rarely inherited from the second growth surface 25 in the second growth crystal 10, and the dislocations are hardly inherited. In addition, there are almost no defects and the quality is high.

In this example, the first growth surface 1
The deposits and work-affected layers are removed before the SiC single crystal is grown on the No. 5 and second growth surface 25. for that reason,
It is possible to prevent dislocations that are inherited from the growth surfaces 15 and 25 to the grown crystals 10 and 20 due to the deposits and work-affected layers.

Further, the thickness of each of the various crystals is set to 1 mm or more. Therefore, it is possible to prevent dislocations and stacking faults occurring 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.

As described above, according to this example, it is possible to provide a high-quality SiC single crystal containing few defects and dislocations and a method for producing the same.

(Embodiment 2) This embodiment shows an example in which the tilt angle γ in the second growth step of Embodiment 1 is changed to 90 ° to produce a SiC single crystal. First, the same Si as in the first embodiment
A C single crystal 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. Then, the first grown crystal 10 was obtained in the same manner as in Example 1 (first growth step).

Next, as shown in FIGS. 3 and 4, <11
From the first tilt direction 153, which is the −20> direction, to <0001
Is rotated by β (β = 90 ° in this example), that is, it has a second inclination direction 253 in the <1-100> direction, and an inclination angle γ (γ in this example) from the {0001} plane.
= 90 °) A second seed crystal 2 having a tilted surface exposed as a 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 the second seed crystal 2 of the second seed crystal 2 is grown as shown in FIG.
The second growth crystal 2 is formed by growing a SiC single crystal on the growth surface 25.
0 was produced as the final SiC single crystal (continuous growth step). Also in this example, similar to Example 1, micropipe defects, dislocations, etc. were very small, and a high-quality SiC single crystal could be obtained.

(Embodiment 3) This embodiment shows an example in which a SiC single crystal is produced with the inclination angles α and γ in the first and second growth steps of Embodiment 1 being both 90 °. First, the same SiC single crystal as in Example 1 was prepared. From the {0001} plane of the above SiC single crystal, <11-2
Inclination angle α (α =
The SiC single crystal is cut so that the surface inclined at 90 °) is exposed as the first growth surface 15, and the first growth surface 1 is cut.
5 was processed and polished. In addition, in the same manner as in Example 1, the first
The surface of the growth surface 15 is chemically cleaned to remove deposits, and RI
E (Reactive Ion Etching), sacrificial oxidation to remove the work-affected layer due to cutting and polishing,
This was designated as a first seed crystal 1. The thickness of the first seed crystal 1 is 2 mm. Subsequently, the first grown crystal 10 was obtained in the same manner as in Example 1 (first growth step).

Next, as shown in FIGS. 3 and 4, <11
From the first tilt direction 153, which is the −20> direction, to <0001
Is rotated by β (β = 90 ° in this example), that is, it has a second inclination direction 253 in the <1-100> direction, and an inclination angle γ (γ in this example) from the {0001} plane.
= 90 °) A second seed crystal 2 having a tilted surface exposed as a 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 the second seed crystal 2 of the second seed crystal 2 is grown as shown in FIG.
The second growth crystal 2 is formed by growing a SiC single crystal on the growth surface 25.
0 was produced as the final SiC single crystal (continuous growth step). Also in this example, similar to Examples 1 and 2, micropipe defects, dislocations, etc. are very small and high quality SiC is obtained.
A single crystal could be obtained.

(Embodiment 4) In this embodiment, an example in which N = 4, that is, a growth step is performed four times to produce a SiC single crystal is shown. First, the same SiC single crystal as in Example 1 was prepared.
In the first growth step, similarly to the first to third embodiments, from the SiC single crystal, from the {0001} plane, <11-20>
The first seed crystal 1 in which the surface inclined at the inclination angle α (α = 90 ° in this example) in the first inclination direction 153, which is the direction, is exposed as the first growth surface 15 is prepared. A SiC single crystal was grown on the first growth surface 15 to obtain a first grown crystal 10.

Next, in the second growth step with n = 2, as in the first to third embodiments, β is set from the first tilt direction 153, which is the <11-20> direction, to the rotation axis from <0001>.
When rotated (β = 90 ° in this example), that is, <1-1
00> direction has a second inclination direction 253, and {000
The second seed crystal 2 exposed as a second growth surface 25 is a surface inclined at an inclination angle γ (γ = 90 ° in this example) from the 1} plane.
It is made from the grown 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 grown crystal 20.

Next, in the third growth step in which n = 3, a 90 ° rotation about <0001> from the second tilt direction 153, which is the <1-100> direction, ie, <11-20. Has a third tilt direction in the> direction and {0
A third seed crystal in which a surface inclined at an inclination angle of 3 ° from the 001} plane was exposed as a third growth surface was prepared in the same manner as the second seed crystal 2. The thickness of the third seed crystal at this time was 2 mm. Then, this third seed crystal was grown in the same manner as the first and second seed crystals to produce a third grown crystal. The third grown crystal was of high quality with very few micropipe defects and dislocations.

Next, in the fourth growth step in which n = 4, <00 from the third tilt direction which is the <11-20> direction.
When rotated by 90 ° with 01> as the axis of rotation, that is <1
Has a fourth tilt direction in the −100> direction, and {000
A fourth seed crystal in which a surface inclined at an inclination angle of 3 ° from the 1} plane was exposed as a fourth growth surface 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, this fourth seed crystal was grown in the same manner as the first to third seed crystals to produce a fourth grown crystal. The fourth grown crystal had very few micropipe defects, dislocations, etc., and was of the same or higher quality as the third grown crystal.

(Embodiment 5) In this embodiment, an example of producing a SiC wafer with an epitaxial film is shown. As shown in FIG. 8, the method of manufacturing the SiC wafer 4 with the epitaxial film of the present example is performed by exposing the film formation surface 35 from the SiC single crystal.
A wafer 3 is manufactured, and the film formation surface 35 of the SiC wafer 3 is formed.
An epitaxial film 30 is formed on top.

First, the high-quality SiC obtained in Example 3 was used.
A single crystal 20 was prepared. {00 of this SiC single crystal 20
A plane inclined 5 ° from the 01} plane in the <11-20> direction, {1
Three types of SiC wafers were prepared, in which the −100} plane and the {11-20} plane were exposed as film formation surfaces. This SiC
The film-forming surface of the wafer was subjected to surface treatments such as processing, polishing, chemical cleaning, RIE, and sacrificial oxidation in the same manner as in the production of the first seed crystal in Example 1 above.

Then, as shown in FIG. 8, the epitaxial film 30 is formed on the film forming surface 35 of the SiC wafer 3 by the chemical vapor deposition method, and the SiC with the epitaxial film is formed.
Wafer 4 was produced. Specifically, Si is used as a source gas.
H ₄ gas and C ₃ H ₈ gas were introduced into the reaction tube at 5 ml / min and H ₂ gas as a carrier gas at 10 l / min, respectively, and the temperature of the susceptor holding the SiC wafer was set at 1550. The film was formed at a temperature of 10 ° C. and an atmospheric pressure of 10 kPa.

The defect density of micropipe defects, dislocations, inclusions, etc. in the epitaxial film 30 in this example is very small, and high quality Si with an epitaxial film is provided.
C wafer 4 could be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a plane orientation of a first growth surface according to Examples 1 to 5.

FIG. 2 is an explanatory diagram showing a growth direction and a dislocation direction of a first grown crystal according to Examples 1 to 5.

FIG. 3 is an explanatory diagram showing a relationship between a first tilt direction and a second tilt direction according to Examples 1 to 5.

FIG. 4 is an explanatory view showing a plane orientation of a second growth surface according to Examples 1 to 5.

FIG. 5 is an explanatory diagram showing a growth direction of a second grown crystal according to Examples 1 to 5.

FIG. 6 is a diagram illustrating an example of S by sublimation reprecipitation method according to Examples 1 to 5.
Explanatory drawing which shows the growth method of iC single crystal.

FIG. 7 is an explanatory diagram showing main plane orientations of a SiC single crystal according to Example 1.

FIG. 8: Si with an epitaxial film according to Example 5
Explanatory drawing of C wafer.

[Explanation of symbols]

1. ． ． First seed crystal, 15. ． ． First growth plane, 151. ． ． Normal vector (first growth step), 153. ． ． First tilt direction, 10. ． ． First grown crystal, 2. ． ． Second seed crystal, 25. ． ． Second growth plane, 251. ． ． Normal vector (second growth step), 253. ． ． Second tilt direction, 20. ． ． Second grown crystal, 3. ． ． SiC wafer, 35. ． ． Deposition surface, 30. ． ． Epitaxial film, 4. ． ． SiC wafer with epitaxial film,

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Kondo             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F term (reference) 4G077 AA02 BE08 DA02 DB04 DB07                       EA02 ED05 HA12 SA04                 5F045 AA03 AB06 AC01 AC07 AD18                       AE23 AF02 AF13 BB12 HA03

Claims (12)

[Claims] 1. A manufacturing method for manufacturing a bulk SiC single crystal by growing an 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 ≧ 2). (N is a natural number), and each growth step is represented as an nth growth step (n is a natural number and an ordinal number starting from 1 and ending with N), in the first growth step where n = 1, { Inclination angle 1 ° to 9 from the 0001} plane
A first seed crystal having a surface inclined by 0 ° exposed as a first growth surface is prepared, and SiC is formed on the first growth surface of the first seed crystal.
A single crystal is grown to make a first grown crystal, and n = 2.
3 ,. ． ． , N in the continuous growth step, if the direction of the vector obtained by projecting the normal vector of the n-th growth surface onto the {0001} plane is the n-th tilt direction, then from the (n-1) -th tilt direction, <0001 > As the rotation axis 45 ° to 135
It has the n-th tilting direction when rotated by
The n-th seed crystal in which a surface tilted at an inclination angle of 1 ° to 90 ° from the 1} plane is exposed as the n-th growth surface is prepared from the (n-1) -th grown crystal, and SiC on the growth surface
A method for producing a SiC single crystal, which comprises growing a single crystal to produce an nth grown crystal. 2. The n-th growth surface (n
= 1, 2 ,. ． ． , N) and the tilt angle between the {0001} plane and the {0001} plane is less than 70 °. 3. The tilt angle between the nth growth plane (n = 1, 2, ..., N) and the {0001} plane is 10 ° or more according to claim 1 or 2. A method for producing a SiC single crystal. 4. The SiC according to claim 1, wherein in the Nth growth step where n = N, the inclination angle between the Nth growth plane and the {0001} plane is 20 ° or less.
Method for producing single crystal. 5. The n-th growth step (where n ≠ N) according to claim 1 or 4, wherein the n-th growth surface and {00
A method for producing a SiC single crystal, comprising one or more growth steps having an inclination angle of 60 ° to 90 ° with respect to the 01} plane. 6. The method according to any one of claims 1 to 5,
A method for producing a SiC single crystal, characterized in that a sublimation reprecipitation method is used for growing the SiC single crystal on the above various crystals. 7. The method according to any one of claims 1 to 6,
The method for producing a SiC single crystal, wherein the thickness of each of the various crystals is 1 mm or more. 8. A SiC single crystal manufactured by the manufacturing method according to claim 1. 9. A SiC wafer having a film-forming surface exposed from the SiC single crystal produced by the manufacturing method according to claim 1, is formed, and is formed on the film-forming surface of the SiC wafer. A method for manufacturing an SiC wafer with an epitaxial film, which comprises forming an epitaxial film. 10. The film-forming surface according to claim 9,
A surface having an offset angle of 0.5 ° to 20 ° from the {0001} plane, a surface having an offset angle of 20 ° or less from the {1-100} plane, or a surface having an offset angle of 20 ° or less from the {11-20} plane. S with an epitaxial film
iC wafer manufacturing method. 11. A SiC wafer with an epitaxial film, which is manufactured by the manufacturing method according to claim 9. 12. A SiC electronic device using the SiC wafer with an epitaxial film according to claim 11.