JP2002226300A - Silicon carbide and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon carbide manufacturing method capable of reducing warpage and distortion due to anti-phase region boundary surface and / or internal stress, and to reduce warpage and distortion due to anti-phase region boundary surface and / or internal stress. Provided is single crystal silicon carbide and a method for producing the same. SOLUTION: A method for producing silicon carbide in which silicon carbide is deposited on a substrate surface from, for example, a gas phase or a liquid phase. The substrate surface has a plurality of undulations extending substantially in parallel, the undulations having a center line average roughness in the range of 3 to 1000 nm, and the slope of the undulations having a slope of 1 ° to 54.7 °. In the range,
And in a cross section orthogonal to the direction in which the undulation extends,
The shape of the portion where the slopes are adjacent to each other is curved. The substrate is silicon or silicon carbide. For example, the normal axis of the surface is in the <001> direction, and ｛0 occupying the area of the substrate surface.
The ratio of the 01% plane does not exceed 10%. Surface defect density of 10
Single crystal silicon carbide having an internal stress of not more than 00 / cm ^{2 and not} more than 100 MPa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a single crystal silicon carbide film useful as an electronic material and a method for manufacturing the same. In particular, the present invention relates to single-crystal silicon carbide having a low defect density and a small crystal lattice distortion, which are preferable for manufacturing a semiconductor device, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, the growth of silicon carbide (SiC) has been classified into bulk growth by a sublimation method and formation of a thin film by epitaxial growth on a substrate. In bulk growth by sublimation, hexagonal (6H, 4H)
H etc.) The growth of silicon carbide is possible and the production of a substrate of SiC itself has been realized. However, many defects (micropipes) are introduced into the crystal, and it is difficult to increase the substrate area.

On the other hand, when an epitaxial growth method on a single crystal substrate is used, controllability of impurity addition can be improved, the substrate area can be increased, and micropipes, which have been problems in the sublimation method, can be reduced. However, in the epitaxial growth method, there is often a problem of an increase in stacking fault density due to a difference in lattice constant between the substrate material and the silicon carbide film. In particular, since silicon generally used as a substrate to be grown has a large lattice mismatch with silicon carbide, twin (Twin) and anti-phase region boundary surface (APB) in the silicon carbide growth layer. Remarkably occur, and these impair the characteristics of silicon carbide as an electronic element.

[0004] As a method of reducing surface defects in a silicon carbide film, for example, a step of providing a growth region on a growth target substrate;
A step of growing a silicon carbide single crystal in this growth region so that its thickness is equal to or greater than the thickness inherent to the growth plane orientation of the substrate, thereby reducing plane defects after the inherent thickness. (Japanese Patent Publication No. 6-41400). However, the two types of anti-phase regions included in silicon carbide have a characteristic of expanding in directions orthogonal to each other as the thickness of silicon carbide increases.
The anti-phase region boundary cannot be effectively reduced.
Furthermore, since it is not possible to arbitrarily control the direction of the superstructure formed on the surface of the grown silicon carbide, for example, when discrete growth regions are combined with growth,
There is a problem that an antiphase region boundary surface is newly formed at this coupling portion, and electrical characteristics are impaired.

[0005]

As a method of effectively reducing the antiphase region boundary surface, K. Shibahara et al. Slightly inclined the surface normal axis from the <001> direction to the <110> direction (off angle). A growth method on Si (001) surface substrate (introduced by A.P.F.), 50
Vol., 1987, p. 1888). In this method, since the steps at the atomic level are introduced at equal intervals in one direction by imparting a slight inclination to the substrate, a plane defect in a direction parallel to the introduced steps propagates, while the introduced steps are formed. This has the effect of suppressing the propagation of surface defects in a direction perpendicular to the plane (a direction crossing the step). Therefore, of the two types of anti-phase regions included in the silicon carbide film, the anti-phase region expanding in the direction parallel to the introduced step is the anti-phase region expanding in the orthogonal direction. Since the enlargement is performed preferentially as compared with the phase region, the anti-phase region boundary surface can be effectively reduced. However, as shown in FIG.
By increasing the step density at the silicon carbide / silicon substrate interface,
There is a problem that undesired generation of the anti-phase region boundary surface 1 and twins is caused, and the anti-phase region boundary surface is not completely eliminated. In FIG. 1, reference numeral 1 denotes an anti-phase region boundary surface generated in a single atom step of the silicon substrate;
Is the anti-phase region boundary junction, 3 is the anti-phase region boundary generated on the surface terrace of the silicon substrate, θ is the off angle, and φ is Si
The angle (54.7) formed by the (001) plane and the antiphase region boundary surface
°). The anti-phase region boundary surface 3 generated on the surface terrace of the silicon substrate disappears at the anti-phase region boundary surface meeting point 2, but the anti-phase region boundary surface 1 generated at the single atom step of the silicon substrate has no association partner. Does not disappear.

Further, when silicon carbide is formed on a silicon substrate, the difference in the coefficient of thermal expansion between silicon and silicon carbide, the mismatch of lattice constants, the defects generated in silicon carbide, or the effects of strain cause the silicon carbide to form. Internal stress occurs in the layer.
Due to the internal stress generated in the silicon carbide layer, the silicon carbide formed on the silicon substrate is warped or distorted, and it is difficult to use this as a semiconductor element material.

It is an object of the present invention to provide a method of manufacturing silicon carbide that can effectively reduce the anti-phase region boundary surface and a method of manufacturing silicon carbide that can reduce warpage and distortion due to internal stress. It is a further object of the present invention to provide a single-crystal silicon carbide in which warpage and distortion associated with an antiphase region boundary surface and / or an internal stress are reduced, and / or a method for manufacturing the same.

[0008]

Means for Solving the Problems To achieve the above object, the present invention is as follows. [Claim 1] In a method of manufacturing silicon carbide for depositing silicon carbide on at least a part of a substrate surface, the substrate surface on which the silicon carbide is deposited has a plurality of undulations extending substantially in parallel, and the undulations are centered. The linear average roughness is in the range of 3 to 1000 nm, and the slope of the undulating slope is 1 ° to 54.7 °.
And a cross section perpendicular to the direction in which the undulations extend, the shape of the portion where the slopes are adjacent to each other is curved. [2] In a method for producing silicon carbide in which silicon carbide is deposited on at least a part of a substrate surface, the substrate surface on which the silicon carbide is deposited has a plurality of undulations extending substantially in parallel, and the undulations are centered. The linear average roughness is in the range of 3 to 1000 nm, and the slope of the undulating slope is 1 ° to 54.7 °.
Wherein the substrate is silicon or silicon carbide,
A method for producing silicon carbide, wherein the normal axis of the surface has a <001> orientation, and the ratio of the {001} plane to the area of the substrate surface does not exceed 10%. [3] In a method for producing silicon carbide in which silicon carbide is deposited on at least a part of a substrate surface, the substrate surface on which the silicon carbide is deposited has a plurality of undulations extending substantially in parallel, and the undulations are centered. The linear average roughness is in the range of 3 to 1000 nm, and the slope of the undulating slope is 1 ° to 54.7 °.
Wherein the substrate is silicon or cubic silicon carbide, the normal axis of the surface of which is in the <111> direction, and the ratio of the {111} plane occupying the area of the substrate surface does not exceed 3%. A method for producing silicon carbide, which is characterized by the following. [4] In a method of manufacturing silicon carbide for depositing silicon carbide on at least a part of a substrate surface, the substrate surface on which the silicon carbide is deposited has a plurality of undulations extending substantially in parallel, and the undulations are centered. The linear average roughness is in the range of 3 to 1000 nm, and the slope of the undulating slope is 1 ° to 54.7 °.
Wherein the substrate is hexagonal silicon carbide, the normal axis of the surface of which is in the <1,1, -2,0> direction, and ｛1,1, -2,0 occupying the area of the substrate surface. ｝ Surface ratio is 10%
A method for producing silicon carbide, wherein [5] In a method of manufacturing silicon carbide for depositing silicon carbide on at least a part of the surface of the substrate, the surface of the substrate on which the silicon carbide is deposited has a plurality of undulations extending substantially in parallel, and the undulations are centered. The linear average roughness is in the range of 3 to 1000 nm, and the slope of the undulating slope is 1 ° to 54.7 °.
Wherein the substrate is hexagonal silicon carbide, the normal axis of the surface of which is in the <0,0,0,1> direction, and the {0,0,0,1} plane occupying the area of the substrate surface. Is not more than 3%. [6] The method according to any one of [1] to [5], wherein the precipitation of silicon carbide is performed from a gas phase or a liquid phase. [7] The manufacturing method according to any one of [2] to [6], wherein in a cross section orthogonal to the direction in which the undulations of the substrate surface extend, the shape of the portion where the slopes are adjacent to each other is curved. [Claim 8] Single-crystal silicon carbide having a plane defect density of 1000 / cm ² or less. [Claim 9] Single-crystal silicon carbide having an internal stress of 100 MPa or less. [Claim 10] Single-crystal silicon carbide having a planar defect density of 1000 / cm ² or less and an internal stress of 100 MPa or less. [Claim 11] An etch pit density of 10 / cm ² or less and a twin density of 4 × 10 ⁻⁴ Vol. % Or less, single-crystal silicon carbide. [Claim 12] In the manufacturing method according to any one of claims 1 to 7, the silicon carbide is deposited by epitaxial growth while inheriting the crystallinity of the substrate surface. 13. The method for producing single-crystal silicon carbide according to item 10.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Invention of Claim 1] Claim 1
In the invention described in (1), a substrate having a plurality of undulations extending substantially in parallel on a substrate surface on which silicon carbide is deposited is used. By using a substrate having a plurality of undulations on its surface in this manner, the effect of introducing the off-angle shown by K. Shibahara et al. On the slope of each undulation can be obtained. In addition, by using a substrate having a plurality of undulations on its surface, it becomes possible to improve surface defects in silicon carbide deposited on the substrate, reduce distortion, and reduce internal stress of silicon carbide. .

The undulation according to the present invention does not require a mathematically strict sense of parallelism or mirror symmetry, but can effectively reduce or eliminate an antiphase region boundary surface. What is necessary is just to have a sufficient degree of form. In addition, the undulations according to the present invention are formed by repetition of peaks and valleys, and are not so-called atomic steps. Undulating in range. further,
The peak has a slope having an inclination of 1 to 54.7 ° with respect to the basal plane. Further, the slopes of the adjacent peaks are formed so as to face each other across the valley. Preferably, when the inclination angle of the undulating surface with respect to the base surface is integrated over the entire surface, the integrated value is formed to have a shape of substantially 0 °.

The undulation of the substrate surface has a center line average roughness of 3
〜1000 nm. Center line average roughness 3nm
If it is less than 30%, it is difficult to obtain an effective off-angle, and the density of surface defects increases, which is not sufficient. On the other hand, if the center line average roughness exceeds 1000 nm, the probability that the surface defects will collide with each other and be eliminated is reduced, and the effect of the present invention cannot be obtained. Therefore, the substrate surface has a center line average roughness of 3 nm or more and 100
0 nm or less. In order to obtain the effects of the present invention more effectively, the center line average roughness is 10 nm or more;
And 100 nm or less.

The center line average roughness of the substrate surface is B0601-
The center line average roughness (Ra) defined in 1982 (JIS Handbook 1990) .A part of the measured length L is extracted from the roughness curve in the direction of the center line, and the center line of the extracted part is X.
When the direction of the axis and the vertical magnification is the Y axis, and the roughness curve is represented by y = f (x), the value represented by the following equation is represented by (μm).

[0013]

[Number 1] Ra = (1 / L) ∫ 1 0 │f (x) │dx

In the definition of JIS B0601-1982, the unit of the center line average roughness is μm, but in the present invention, nanometer (nm) is used. Further, a roughness curve for obtaining the center line average roughness (Ra) is measured using an atomic force microscope (AFM).

[0015] Further, the slope of the undulating slope extending on the substrate surface is in the range of 1 ° or more and 54.7 ° or less. In the method of the present invention, the effect is exhibited by promoting the growth of silicon carbide in the vicinity of the step at the atomic level on the surface of the growth target substrate. The present invention is realized at an inclination of the covered (111) plane of 54.7 ° or less. When the inclination is less than 1 °, the step density of the undulating slope is significantly reduced.
That is all. Further, from the viewpoint that the effects of the present invention are more effectively exhibited, the inclination angle of the undulating slope is preferably 2 ° or more and 10 ° or less. In the present invention, the “inclined slope” includes all forms such as a flat surface and a curved surface. Further, in the present invention, the “slope of the undulating slope” means a substantial slope of the slope which contributes to the effect of the present invention, and means an average slope of the slope. The average inclination means the angle at which the crystal orientation plane of the substrate surface intersects with the slope (average value of the evaluation area).

Further, in a cross section orthogonal to the direction in which the undulations extend, the shape of a portion where slopes existing on the substrate surface are adjacent to each other is curved. The portions where the slopes are adjacent to each other are the portion of the undulating groove and the ridge extending on the surface, and the cross-sectional shape of both the bottom of the groove and the top of the ridge is curved. This state can also be seen from the electron micrograph shown in FIG. That is, the cross-sectional shape of the undulation in a cross section orthogonal to the direction in which the undulation extends has a shape like a kind of sine wave, although the wavelength and the wave height need not be constant. As described above, the cross-sectional shape of both the bottom of the groove and the top of the ridge is curved, so that the surface defect density can be reduced.

As described above, by providing a plurality of undulations on the surface of the silicon carbide growth substrate, it is possible to obtain the effect of introducing the off angle shown by K. Shibahara et al. On the slope of each undulation. . The distance between the tops of the undulations is preferably 0.01 μm or more from the viewpoint of the limit of the fine processing technique in the preparation of undulations on the substrate to be grown. On the other hand, if the interval between the tops of the undulations exceeds 1000 μm, the frequency of association between the boundary surfaces of the anti-phase regions is extremely reduced.
It is desirable that the thickness be not more than 00 μm. Further, the distance between the tops of the undulations is preferably 0.1 μm or more and 100 μm or less from the viewpoint that the effects of the present invention are sufficiently exhibited.

The difference between the heights of the undulations and the spacing determines the inclination of the undulations, that is, the step density. Although the preferred step density varies depending on the crystal growth conditions, it cannot be unconditionally determined.

In the present invention, a silicon carbide film is formed on the entire substrate as described above or a partial region of the substrate (the region having the plurality of undulations) as one growth region. It is formed continuously. By providing the substrate with such undulations, it is possible to associate the growing antiphase phase boundary surface generated from the steps existing on the slope with the growth of silicon carbide between the plurality of undulations. is there. Therefore, the anti-phase region boundary surface can be effectively eliminated and removed, and single crystal silicon carbide with few defects can be obtained.

In the first aspect of the present invention, as the material of the substrate, for example, a single crystal substrate of silicon, silicon carbide, sapphire, or the like can be used. These points are common to the inventions described in other claims of the present invention.

[Invention of Claim 2] In the invention of Claim 2, similarly to the invention of Claim 1, as a substrate on which silicon carbide is deposited, the surface thereof extends substantially in parallel. It has a plurality of undulations, and this undulation has a center line average roughness of 3
A substrate is used which is in the range of １０００1000 nm and whose slope of the undulation is in the range of 1 ° to 54.7 °.
The reason for limiting the numerical value of the center line average roughness of the undulations and the preferred numerical range, the reason for limiting the numerical value of the slope of the undulating slope and the preferred numerical range, and other explanations about common points regarding the manufacturing method and the like are described in claim 1. This is the same as the described invention. However, in the invention described in claim 2, the substrate is silicon or silicon carbide, and the normal axis of the surface is <0.
01> orientation and occupies {001} in the area of the substrate surface
The aspect ratio is not more than 10%. As described above, by providing undulations on the substrate surface and controlling the ratio of the smooth surface remaining on the substrate surface, it is possible to control the internal stress of silicon carbide deposited and formed thereon.

On the (001) plane, a crystal phase grows in the <001> direction, and stress is generated in the film in the direction of tension. However, by forming undulations on the substrate surface and increasing the proportion of the (111) plane, A compressive stress that offsets the tensile stress of the (001) plane is intentionally generated, and as a result, the in-plane stress can be reduced. For example, when the proportion of the (001) plane is controlled to 10% or less of the plane of the substrate, an undulating slope including the (111) plane and the like is formed, and an undulating substrate is used in which growing crystal phases collide with each other. A tensile stress acting in the <001> direction and a compressive stress acting in a direction perpendicular to the <001> direction occur in the silicon carbide layer grown on the substrate, and the stresses cancel each other. This can be used to control the stress. The lower limit of the ratio of the {001} plane to the area of the substrate surface is ideally 0%.

[Invention of Claim 3] In the invention of Claim 3, as in the invention of Claim 1, as a substrate on which silicon carbide is deposited, the surface thereof extends substantially in parallel. It has a plurality of undulations, and this undulation has a center line average roughness of 3
A substrate is used which is in the range of １０００1000 nm and whose slope of the undulation is in the range of 1 ° to 54.7 °.
The reason for limiting the numerical value of the center line average roughness of the undulations and the preferred numerical range, the reason for limiting the numerical value of the slope of the undulating slope and the preferred numerical range, and other explanations about common points regarding the manufacturing method and the like are described in claim 1. This is the same as the described invention. However, in the invention described in claim 3, the substrate is silicon or cubic silicon carbide, the normal axis of the surface of which is in the <111> direction, and occupying the area of the substrate surface.
It is characterized in that the ratio of the 11% plane does not exceed 3%. In this way, by providing undulations on the substrate surface and controlling the ratio of the smooth surface remaining on the substrate surface, the inside of the silicon carbide deposited and formed thereon as in the case of the invention according to claim 2. Control of stress becomes possible. ｛1 occupying the area of the substrate surface
The lower limit of the ratio of the 11 ° plane is ideally 0%.

[Invention of Claim 4] Also in the invention of claim 4, similarly to the invention of claim 1, as a substrate on which silicon carbide is deposited, the surface thereof extends substantially in parallel. It has a plurality of undulations, and this undulation has a center line average roughness of 3
A substrate is used which is in the range of １０００1000 nm and whose slope of the undulation is in the range of 1 ° to 54.7 °.
The reason for limiting the numerical value of the center line average roughness of the undulations and the preferred numerical range, the reason for limiting the numerical value of the slope of the undulating slope and the preferred numerical range, and other explanations about common points regarding the manufacturing method and the like are described in claim 1. This is the same as the described invention. However, in the invention described in claim 4, the substrate is hexagonal silicon carbide, and the normal axis of the surface is <1,1,
−2,0> azimuth, and ｛1,
It is characterized in that the ratio of the 1, -2,0 ° plane does not exceed 10%. In this way, by providing undulations on the substrate surface and controlling the ratio of the smooth surface remaining on the substrate surface, the inside of the silicon carbide deposited and formed thereon as in the case of the invention according to claim 2. Control of stress becomes possible. The lower limit of the ratio of the {1,1, -2,0} plane to the area of the substrate surface is ideally 0%. [Invention of claim 5] Also in the invention of claim 5, as in the invention of claim 1, as a substrate on which silicon carbide is deposited, a plurality of undulations whose surfaces extend substantially in parallel are provided. This undulation has a center line average roughness of 3 to 1000 n.
m, and the slope of the undulating slope is in the range of 1 ° to 54.7 °. Numerical limitation reason and preferred numerical range of the center line average roughness of the undulation, numerical limitation reason and preferred numerical range of the slope of the undulation slope,
In addition, the description of the common features regarding the manufacturing method and the like is the same as that of the first aspect of the present invention. However, in the invention according to claim 5, the substrate is hexagonal silicon carbide, and the normal axis of the surface thereof has a <0,0,0,1> direction, and ｛0, It is characterized in that the ratio of the 0,0,1３ plane does not exceed 3%. In this way, by providing undulations on the substrate surface and controlling the ratio of the smooth surface remaining on the substrate surface, the inside of the silicon carbide deposited and formed thereon as in the case of the invention according to claim 2. Control of stress becomes possible. {0,0,0,1} of the surface area of the substrate
The lower limit of the surface ratio is ideally 0%.

[Invention according to claim 6] In addition, claims 1 to
In the invention described in 5, the silicon carbide is deposited from at least a part of the surface of the substrate from a gas phase or a liquid phase. As a method for depositing silicon carbide from a gas phase or a liquid phase, a known method can be used as it is. Dichlorosilane (SiH ₂ Cl ₂ ), SiH ₄ , SiCl ₄ , SiHC are used as a silicon source gas in the method of depositing silicon carbide from a gas phase.
It can be used a silane compound gas, such as l _3. In addition, acetylene (C ₂
Hydrocarbon gases such as H ₂ ), CH ₄ , C ₂ H ₆ , and C ₃ H ₈ can be used. Examples of the liquid phase method include a method of melting polycrystalline or amorphous silicon carbide, and a method of forming silicon carbide from a silicon source and a carbon source. [Invention according to claim 7] The invention according to claim 7 is the invention according to any one of claims 2 to 6, wherein the inclined surface is formed in a cross section orthogonal to the direction in which the undulation of the substrate surface extends. It is characterized in that the shape of the part where they are adjacent to each other is curved. The portions where the slopes are adjacent to each other are the portion of the undulating groove and the ridge extending on the surface, and the cross-sectional shape of both the bottom of the groove and the top of the ridge is curved. This state can also be seen from the electron micrograph shown in FIG. That is,
The cross-sectional shape of the undulation does not need to be constant in wavelength and wave height, but has a shape like a kind of sine wave. As described above, the cross-sectional shape of both the bottom of the groove and the top of the ridge is curved, so that the surface defect density can be reduced.

In order to form the undulation having the above-mentioned shape on the surface of the substrate, for example, an optical lithography technique, a press working technique, a laser working, an ultrasonic working technique, a polishing working technique, or the like can be used. Regardless of which method is used, the final form of the surface of the substrate to be grown has a form sufficient to effectively reduce or eliminate the anti-phase region boundary as described in each claim. I just want to.

If the photolithography technique is used, it is possible to arbitrarily form an undulating shape on the substrate to be grown by arbitrarily forming a mask pattern to be transferred onto the substrate. It is possible to control the width of the undulating shape by changing the line width of the pattern, for example, and to control the depth of the undulating shape and the angle of the slope by controlling the etching selectivity between the resist and the substrate. It is possible. In a cross section orthogonal to the direction in which the undulations of the substrate surface extend, when forming a substrate in which the shape of the portion where the slopes are adjacent to each other is curved,
After the pattern is transferred to the resist, the resist is softened by heat treatment, so that an undulating pattern having a cross-sectional curved shape (wavy shape) can be formed.

By using the press working technique, it is possible to form an arbitrary undulation on the substrate to be grown by arbitrarily forming a press die. By forming molds of various shapes, various undulating shapes can be formed on the growth target substrate.

If laser processing or ultrasonic processing technology is used, finer processing is possible because the undulating shape is formed directly on the substrate. If the polishing process is used, the width and depth of the undulating shape can be controlled by changing the size of the abrasive grain and the processing pressure of the polishing. When a substrate having a one-way undulation is to be manufactured, polishing is performed only in one direction.

If dry etching is used, the width and depth of the undulating shape can be controlled by changing the etching conditions and the shape of the etching mask.
In a cross section orthogonal to the direction in which the undulations of the substrate surface extend, when forming a substrate in which the shape of the portion where the slopes are adjacent to each other is curved, by disposing the etching mask away from the pattern transfer substrate, Since the etching is diffused between the mask and the substrate, a wavy pattern having a curved cross section can be transferred. Alternatively, the mask may have a trapezoidal shape in which the cross section of the window of the mask is widened toward the pattern transfer substrate side.

[Invention of claim 8] The invention of claim 8 is a single crystal silicon carbide characterized by having a planar defect density of 1000 / cm ² or less. Conventionally, single-crystal silicon carbide has been known. However, conventional single-crystal silicon carbide has a planar defect density of more than 10 ⁴ / cm ² (for example, AL, Syrkin et al., Inst. Phys. Conf. Ser. No. 1).
42, p189). In contrast, the single crystal silicon carbide of the present invention has a planar defect density of 1000 / cm ² or less, preferably 1 / cm ^2.
00 / cm ² or less. The lower limit of the planar defect density is ideally 0 / cm ² , and is practically about 0.1 / cm ² . Such single-crystal silicon carbide has very low electrical characteristics because of its low crystal boundary density, and can be suitably used as a semiconductor substrate, a substrate for crystal growth (including a seed crystal), and other electronic elements.

[Invention according to claim 9] The invention according to claim 9 is a single crystal silicon carbide having an internal stress of 100 MPa or less. Conventionally, single-crystal silicon carbide has been known. However, conventional polycrystalline silicon carbide has an internal stress exceeding 100 MPa (for example,
T.Shoki et al., SPIE. Int. Soc. Opt. Eng. Vol. 3748 p45
6). On the other hand, the single crystal silicon carbide of the present invention has an internal stress of 100 MPa or less, preferably 50 MPa or less. The lower limit of the internal stress is ideally 0 MPa,
In reality, it is 50 MPa. Such single crystal silicon carbide has a small warpage and distortion of silicon carbide, and can provide smooth silicon carbide. In a state where silicon carbide is warped due to internal stress, distortion occurs on the surface of silicon carbide. For example, if silicon carbide is to be newly deposited on the silicon carbide as a substrate, silicon carbide will be deposited while inheriting the strain. However, such a problem can be avoided by using the single-crystal silicon carbide of the present invention, which has an internal stress of 100 MPa or less and has no distortion, as the substrate.

According to a tenth aspect of the present invention, there is provided a single-crystal silicon carbide having a planar defect density of 1000 / cm ² or less and an internal stress of 100 MPa or less. It is. As described above, the conventional single-crystal silicon carbide has a plane defect density exceeding 10 ⁴ / cm ^2, and there is no single-crystal silicon carbide having an internal stress of about 100 MPa. In contrast, the single crystal silicon carbide of the present invention has a planar defect density of 1000 / cm ² or less, preferably 1 / cm ^2.
00 / cm ² or less, and the internal stress is 100 MPa or less, preferably 50 MPa or less. The lower limit of the planar defect density is ideally 0 / cm ² , and is actually 0.1 / cm ^2.
/ Cm ² . The lower limit of the internal stress is ideally 0 MPa, and is actually 50 MPa. Such single-crystal silicon carbide has very low electrical characteristics due to low crystal boundary density, and can be suitably used as a semiconductor substrate, a substrate for crystal growth (including a seed crystal), and other electronic elements. In addition, it is possible to provide a smooth silicon carbide having a small warpage and distortion of the silicon carbide.

[Invention according to claim 11] The invention according to claim 11 has an etch pit density of 10 / cm ² or less and a twin density of 4 × 10 ^-4 Vol. % Or less of single crystal silicon carbide. The etch pit density affects the yield of a device using the single-crystal silicon carbide of the present invention. If the etch pit density is 10 / cm ² or less, the yield is 90% or more when the device area is 0.01 cm ^2. can get. The etch pit density is preferably 1 / cm ² or less from the viewpoint of further increasing the device yield. The twin density is 4 × 10 ⁻⁴ V
ol. % Or less, the device area is 0.01 c
m ² is preferable from the viewpoint that a yield of 90% or more can be obtained, and is preferably 4 × 10 ⁻⁵ Vol. % Is more preferable.

According to a twelfth aspect of the present invention, there is provided the manufacturing method according to any one of the first to seventh aspects, wherein silicon carbide is deposited and crystallinity of the substrate surface is reduced. The method for producing single-crystal silicon carbide according to any one of claims 8 to 11, wherein the method is carried out by epitaxial growth while taking over. The method of epitaxially growing the deposition of silicon carbide while inheriting the crystallinity of the substrate surface may be any method capable of limiting the propagation direction of the film inner surface defect to a specific crystal plane, such as a chemical vapor deposition (CVD) method. A liquid phase epitaxial growth method, a sputtering method, a molecular beam epitaxy (MBE) method, or the like can be used. Also, CV
In the case of the method D, a simultaneous supply method of the source gas can be used instead of the alternate supply method of the source gas.

According to the twelfth aspect of the present invention, the step of orienting the silicon carbide substrate in a mirror-symmetrical direction on the surface of the substrate to be grown is introduced at a statistically balanced density. The anti-phase region boundaries in the silicon carbide layer introduced into the substrate effectively associate with each other, and a silicon carbide film in which the anti-phase region boundaries are completely eliminated can be obtained. Furthermore, due to the introduction effect of the off angle, all the individual growth regions become in-phase regions that expand in the same direction.
There is also an advantage that an anti-phase region boundary surface does not occur at the joint even when the discrete growth regions are joined together with the growth. That is, according to this method, the mismatch between the lattice constant of the interface between silicon and silicon carbide, which has been a problem when depositing silicon carbide on the silicon substrate, is eliminated, the generation of defects is suppressed, and high-quality carbonization is achieved. Silicon can be formed.

[0037]

The present invention will be described in more detail with reference to the following examples. Reference example To confirm the effect of introducing the off-angle, 6
Silicon carbide (hereinafter 3C-SiC) is grown using the (001) plane of a silicon substrate (hereinafter Si) having an inch Φ and the Si (001) plane with off angles of 4 ° and 10 ° as growth substrates. Was. The growth of 3C-SiC is divided into a carbonization step of the substrate surface and a 3C-SiC growth step by alternate supply of a source gas. In the carbonization step, the processed substrate was heated from room temperature to 1050 ° C. for 120 minutes in an acetylene atmosphere. After the carbonization step, 3C-SiC was grown by alternately exposing dichlorosilane and acetylene to the substrate surface at 1050 ° C. Table 1 shows the detailed conditions of the carbonization step, and Table 2 shows the detailed conditions of the 3C-SiC step. The silicon carbide grown on each substrate was measured for the density of the anti-phase region boundary surface, and the results shown in Table 3 were obtained.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3]

The density of the antiphase region boundary surface is 3C-
The SiC surface was determined by AFM observation. At this time, 3C-S
The surface of the iC was subjected to a thermal oxidation treatment, and the thermal oxide film was further removed to reveal the anti-phase boundary, followed by observation. From the relationship between the off-angle and the anti-phase region boundary surface density shown in Table 3, it can be seen that although the decrease in the anti-phase region boundary surface density due to the introduction of the off-angle was confirmed, it was not completely resolved. 3C-Si grown on a substrate with an off angle of 4 °
FIG. 2 shows a scanning electron micrograph of the surface of the C film, and FIG. 3 shows a scanning electron micrograph of the surface of the 3C-SiC film grown on the substrate having no off-angle. From FIGS. 2 and 3, it was confirmed that the terrace area was increased by the introduction of the off-angle, and 3C-SiC growth in the step flow mode became dominant, and the propagation direction of the plane defect was limited to a specific crystal plane. You can see that it is. However, these defect propagation directions are all parallel and remain without disappearing. Therefore, it is impossible to completely eliminate the antiphase boundary surface defect and the like.

Example 1 An Si (001) plane having a diameter of 6 inches was used as a substrate to be grown, and the surface of the substrate was thermally oxidized, and then 1.5 μm wide, 60 mm long and 1 μm thick were formed on the substrate surface by photolithography.
Was formed with a resist.
However, the direction of the line & space pattern is <110>
Parallel to the direction. By heating this substrate using a hot plate under the conditions shown in Table 4, the line & space resist pattern spreads and deforms in the direction orthogonal to the lines, and the top and bottom of the undulation are connected by a smooth curve. The resist pattern shape of the cross section was obtained. The cross-sectional shape (undulation) and the planar shape (line & space) of this resist pattern were transferred to a silicon substrate by dry etching.

The resist was removed in a mixed solution of hydrogen peroxide and sulfuric acid to obtain a substrate. As a result of electron microscopic observation, this substrate has a plurality of undulations extending substantially parallel to the substrate surface, as shown in FIG. 4, and in a cross section orthogonal to the direction in which the undulations extend, The shape of the portion where the slopes were adjacent was curved. Further, the undulation has a center line average roughness of 100 nm, and the average slope of the undulation slope is 4 nm.
°. The measurement of the center line average roughness and the slope of the undulating slope was performed by an atomic force microscope (AFM).

3C-SiC was grown on this substrate. The growth of 3C-SiC is divided into a carbonization step of the substrate surface and a 3C-SiC growth step by alternate supply of a source gas. Table 5 shows the detailed conditions of the 3C-SiC growth step.
The detailed conditions of the carbonization step were the same as in Table 1. 3C-
In the SiC growth process, the film thickness of 3C-SiC was changed by changing the number of supply cycles of the source gas, and the density of the antiphase region boundary surface appearing on the outermost surface was measured in the same manner as described above. 6 were obtained.

[0045]

[Table 4]

[0046]

[Table 5]

[0047]

[Table 6]

From the relationship between the thickness of the 3C-SiC film and the density of the anti-phase region boundary surface shown in Table 6, it can be seen that as the growth of the 3C-SiC proceeds, the surface defects collide with each other and disappear. It can be seen that the effectiveness of the present invention is remarkable as compared with the values in Table 3 which is the conventional method. Further, the etch pit density and the twin density of the 6-inch Φ3C-SiC obtained in this example were examined as follows. 3C-SiC is melted in KOH (5
(At 0 ° C. for 5 minutes), the surface was observed with an optical microscope. The number of etch pits corresponding to the stacking fault density was 6
1,700 or less in the whole inch, and density 10 / c
m ² or less. Further, pole observation of the X-ray diffraction rocking curve (XRD) with respect to the 3C-SiC <111> direction was performed, and the signal intensity of the {115} plane direction corresponding to the twin plane and the signal intensity of the normal single crystal plane {111} plane were compared. Twin density was calculated from the signal intensity ratio. As a result, the twin density was 4 × 10 ⁻⁴ Vol. %.

Example 2 An Si (001) plane having a diameter of 6 inches was used as a substrate to be grown, and 1.5 μm was formed on the surface of the substrate by photolithography.
A line & space pattern having a width of m, a length of 60 mm, and a thickness of 1 μm was formed using a resist. However, the direction of the line & space pattern was parallel to the <110> direction. The substrate was heated using a hot plate under the conditions shown in Table 7 to soften the resist and change the cross-sectional shape of the resist pattern. Cross section of this resist pattern (undulation)
And the planar shape (line & space) was transferred to the Si substrate by dry etching. The heating temperature of the resist pattern was changed between 150 ° C. and 200 ° C., and the inclination angle θ of the undulation was changed as shown in Table 8. The resist was removed in a mixed solution of hydrogen peroxide and sulfuric acid to obtain a substrate. As a result of electron microscopic observation, this substrate has a plurality of undulations extending substantially parallel to the substrate surface, as shown in FIG. 4, and in a cross section orthogonal to the direction in which the undulations extend, The shape of the portion where the slopes were adjacent was curved. Further, the undulation had a center line average roughness of 100 nm, and the average slope of the undulated slope was as shown in Table 8.
The measurement of the center line average roughness and the slope of the undulating slope was performed in the same manner as in Example 1.

3C-SiC was grown on these substrates. The growth of 3C—SiC includes a carbonization step on the substrate surface,
It is divided into a 3C-SiC growth step by alternate supply of source gases. The detailed conditions of the carbonization step were the same as in Table 1,
The detailed conditions of the 3C-SiC growth step were the same as in Table 5.
For 3C-SiC grown on each substrate,
When the density of the anti-phase region boundary surface appearing on the outermost surface was measured in the same manner as described above, the results shown in Table 8 were obtained.

[0051]

[Table 7]

[0052]

[Table 8]

From the relationship between the gradient of the undulation and the density of the antiphase region boundary surface shown in Table 8, the inclination angle θ of the undulation is particularly (111)
When the angle between the surfaces is less than 54.7 ° and 1 ° or more, a decrease in the density of the antiphase region boundary surface can be confirmed.
Further, as compared with the numerical values in Table 3 which is the conventional method, 3C-SiC grown on the undulating substrate as in the present invention has a significantly reduced or eliminated anti-phase region boundary surface density even at the same off-angle. This indicates that the effectiveness of the present invention is remarkable. In addition, the etch pit density and twin density of 3C-SiC grown on the undulation-processed substrate having an undulation inclination angle of 4 degrees obtained in this example were examined as follows. After exposing 3C-SiC to molten KOH (500 ° C., 5 minutes), the surface was observed with an optical microscope. The number of etch pits corresponding to stacking fault density was 1,528 on the entire surface of 6 inches, and the density was 8 0.65 / cm ² . Furthermore, 3C-SiC <1
11> X-ray diffraction rocking curve (XR
The pole point observation in D) was performed, and the twin density was calculated from the signal intensity ratio of the {115} plane orientation corresponding to the twin plane to the signal intensity ratio of the normal single crystal plane {111} plane orientation. As a result, the twin density was 4 × 10 ⁻⁴ Vol. %.

Embodiment 3 In each of Embodiments 1 and 2, a cubic SiC film was grown on a Si (001) plane substrate. In Example 3, as a substrate to be grown, a substrate having undulations extending parallel to the <110> direction on the (001) plane of cubic silicon carbide (3C-SiC) having a diameter of 6 inches or a single crystal <0,0, on the (1,1, -2,0) plane of hexagonal silicon carbide
A cubic silicon carbide film or a hexagonal silicon carbide film was grown on the surface of each substrate under the same conditions as in Example 1 using a substrate having undulations extending parallel to the 0,1> direction. still,
Each of the substrates has a plurality of undulations extending substantially parallel to the substrate surface, as shown in FIG. 4, as a result of electron microscopic observation, and in a cross section orthogonal to the direction in which the undulations extend. The shape of the portion where the slopes were adjacent to each other was curved. Further, the undulation had a center line average roughness of 100 nm, and the average slope of the undulation was 4 °. As a result, the effectiveness of the present invention was confirmed in the same manner as in Example 1 even when the above substrate was used.

Example 4 <110> was placed on the surface of a Si (001) substrate having a diameter of 6 inches.
An attempt was made to produce an undulation-formed substrate parallel to the <110> direction by a method of performing a polishing treatment parallel to the direction. For polishing, a commercially available diamond slurry having a diameter of about 15 μm (manufactured by Engis: High Press) and a commercially available polishing cloth (manufactured by Engis: M414) were used (Table 9). The diamond slurry is uniformly infiltrated on the cloth, the Si (001) substrate is placed on the pad, and a pressure of 0.2 kg / cm ² is applied to the entire Si (001) substrate while applying a pressure of <110.
One-way polishing was performed by reciprocating 300 times a distance of about 20 cm above the cloth in parallel with the direction. Polishing scratches (scratch) parallel to the <110> direction on the surface of the Si (001) substrate
Were formed innumerably.

[0056]

[Table 9]

Si (001) -based one-way polished
Since abrasive grains are attached to the plate surface, NH_FourOH
+ H_TwoO_Two+ H_TwoO mixed solution (NH_FourOH: H_TwoO_Two: H_TwoO
= 4: 4: 1 at a liquid temperature of 60 ° C.)_TwoS
O_Four+ H_TwoO_TwoSolution (H_TwoSO_Four: H _TwoO_Two= 1: 1 ratio
(Liquid temperature 80 ° C) and HF (10%) solution alternately three times
And rinsed, and finally rinsed with pure water. After cleaning, heat
Using a processing apparatus, under the conditions shown in Table 10,
A thermal oxide film of about 1 μm was formed on the plate. And the thermal oxide film
Removed with HF 10% solution. Just polished
In this case, the substrate surface has fine irregularities and defects in addition to the
Many remain, making it difficult to use as a substrate to be grown. But,
A thermal oxide film is formed about 1 μm and the oxide film is removed again.
Then, the substrate surface is etched about 2000mm and the fine concave
Very smooth undulation with no bumps
(Undulating) surface could be obtained. Looking at the wavy section, it is wavy
The size of the irregularities is unstable and irregular, but the density is high.
At least the (001) plane was 10% or less. Always
It is in a prone state. On average, the center line average roughness is 20n
m. Further, the depth of the groove is 30 to 50 nm, and the width is
It was about 0.5 to 1.5 μm. The slope is 3-5 °
Was. FIG. 4 shows a typical AFM image.

[0058]

[Table 10]

Using this substrate, a 3C-SiC film was formed on the substrate. The growth of 3C-SiC is divided into a carbonization step of the substrate surface and a 3C-SiC growth step by alternate supply of a source gas. The detailed conditions of the carbonization step were the same as in Table 1, and the detailed conditions of the 3C-SiC growth step were the same as in Table 5.

As a result, the effect of the undulating substrate parallel to <110> was obtained. That is, it was confirmed that the number of defects at the antiphase boundary surface was significantly reduced. For example, the anti-phase boundary surface density of a 3C—SiC film grown on an unpolished Si substrate is 8
The anti-phase boundary surface defect density of the 3C-SiC film grown on the unidirectionally polished Si substrate was 0/1 / cm ² , while the density was × 10 ⁹ / cm ² . The undulation shape and the anti-phase boundary surface defect density with respect to the abrasive grain size were as shown in Table 11. Table 12 shows the undulation density and the antiphase boundary surface defect density with respect to the number of times of polishing.

[0061]

[Table 11]

[0062]

[Table 12]

Abrasive grain size 15 μm, number of reciprocating polishing 300
The etch pit density and twin density of 3C-SiC grown on the undulating substrate were examined as follows. 3C-Si
After exposing C to molten KOH (500 ° C., 5 minutes), the surface was observed with an optical microscope. The number of etch pits corresponding to the stacking fault density was 1,414 on the entire surface of 6 inches, and the density was 8.00. / Cm ² . Furthermore, 3C-Si
Pole observation of the X-ray diffraction rocking curve (XRD) with respect to the C <111> direction was performed, and {11} corresponding to a twin plane was observed.
The twin density was calculated from the signal intensity ratio of the 5-plane orientation and the signal intensity of the normal single-crystal plane {111} plane. As a result, the twin density was 4 × 10 ⁻⁴ Vol. %. In this embodiment, a diamond slurry having a diameter of 15 μm was used as the abrasive, but the size and type of the abrasive grains are not limited to these. The larger the particle size, the wider the undulation becomes, and the more gradual it becomes. It is easy to imagine that if the particle size is reduced, the width of the undulations is reduced. If the particle size is about φ1 to 300 μm, it is possible to form effective undulations. The pad is not limited to the above. The load pressure between the substrate and the cloth during polishing, the polishing rate and the number of times are not limited to those described above. In the embodiment, Si (0
Although 01) was used, it goes without saying that the same result as described above can be obtained even when cubic or hexagonal silicon carbide is used. In addition, undulations extending in a direction parallel to the <110> direction were formed on the Si (001) substrate, but the directions are not limited thereto.

Example 5 In order to eliminate distortion and warpage generated in the silicon carbide layer, a polishing treatment was performed in parallel with the <110> direction on the surface of a Si (001) substrate having a diameter of 6 inches by the method of <110>. An attempt was made to fabricate an undulating substrate parallel to the direction. In this example, the effect of the present invention was confirmed by controlling the existence probability of the Si (001) plane by the number of polishing processes. Under the same conditions as in Table 9, the number of polishing was changed from 30 to 300 to
The (001) plane was subjected to a one-way polishing treatment. Si (00
1) Countless polishing scratches (scratch) parallel to the <110> direction were formed on the substrate surface. Since the abrasive grains are attached to the Si (001) substrate that has been subjected to the unidirectional polishing, a mixed solution of NH ₄ OH + H ₂ O ₂ + H ₂ O (NH ₄ OH:
Washing was performed at a liquid temperature of 60 ° C. at a ratio of H ₂ O ₂ : H ₂ O = 4: 4: 1, and an H ₂ SO ₄ + H ₂ O ₂ solution (H ₂ SO ₄ : H ₂ O ₂ =
Washing was performed by alternately soaking three times in a HF (10%) solution and a HF (10%) solution at a ratio of 1: 1 three times, and finally rinsed with pure water.
After the cleaning, a thermal oxide film was formed to about 1 μm on the one-way polished substrate under the conditions shown in Table 10 using a heat treatment apparatus. Then, the thermal oxide film was removed with a HF 10% solution.

Using this substrate, a 3C-SiC film was formed on the substrate. The growth of 3C-SiC is divided into a carbonization step of the substrate surface and a 3C-SiC growth step by alternate supply of a source gas. The detailed conditions of the carbonization step were the same as in Table 1, and the detailed conditions of the 3C-SiC growth step were the same as in Table 5. Table 13 shows the relationship between the abundance of the Si (001) plane, the internal stress of 3C-SiC, and the defect density of the antiphase boundary surface.

[0066]

[Table 13]

The Si (0), which is a 3C-SiC growth underlying substrate,
01) When the Si (001) plane on the substrate is 10% or less,
The result was that the internal stress in the iC layer was 35 MPa or less in the direction of compression. When the Si (001) plane is at least 10%, the results show very high stress, as is clear from the table. Undulation is provided on the Si (001) surface,
It can be said that the effect of controlling the (001) plane to 10% or less appeared. In addition, the defect density tends to increase as the ratio of the Si (001) plane increases. Defect density is also Si
It became clear that the smaller the ratio of the (001) plane, the better. Further, the etch pit density and twin density of 3C-SiC grown on the undulating substrate whose Si (001) plane was controlled to 10% or less were obtained as follows. After exposing 3C-SiC to molten KOH (500 ° C., 5 minutes), the surface was observed with an optical microscope. The number of etch pits corresponding to stacking fault density was 1,548 on the entire surface of 6 inches, and the density was 8 It was 0.76 / cm ² . Furthermore, 3C-SiC <
X-ray diffraction rocking curve (XR
The pole point observation in D) was performed, and the twin density was calculated from the signal intensity ratio of the {115} plane orientation corresponding to the twin plane to the signal intensity ratio of the normal single crystal plane {111} plane orientation. As a result, the twin density was 4 × 10 ⁻⁴ Vol. %. Each of the substrates has a plurality of undulations extending substantially parallel to the substrate surface, as shown in FIG. 4, as a result of electron microscopic observation, and is orthogonal to the direction in which the undulations extend. In the cross section, the shape of the portion where the slopes are adjacent to each other was curved. Further, the undulations had a center line average roughness of 20 to 40 nm, and the average slope of the undulations was 3 to 5 °.

In this embodiment, as described above, Si (001)
Conducted in terms of surface. Similarly, by setting the (111) plane to 3% or less in the Si (111) plane, the (1,1, -2,0) plane in the hexagonal silicon carbide (1,1, -2,0) plane. 10% face
The internal stress in the precipitated SiC layer is set to 3% or less in the (0,0,0,1) plane of the hexagonal silicon carbide by setting the (0,0,0,1) plane below. Can be reduced to 100 MPa or less.

Example 6 In order to eliminate distortion and warpage generated in the silicon carbide layer, a polishing treatment was performed in parallel with the <110> direction on the surface of a Si (001) substrate having a diameter of 6 inches by the method of <110>. An attempt was made to fabricate an undulating substrate parallel to the direction. In this example, the center line average roughness of the Si (001) plane was controlled by the particle size of the abrasive grains, and the effect of the present invention was confirmed. Polishing was performed under the same conditions as in Table 9. On the Si (001) substrate surface,
Innumerable polishing scratches (scratches) parallel to the 110> direction were formed. Since abrasive grains and the like are attached to the Si (001) substrate that has been subjected to the one-way polishing, NH ₄ OH + H ₂ O
₂ + H ₂ O mixed solution (NH ₄ OH: H ₂ O ₂ : H ₂ O = 4:
The solution was washed at a liquid temperature of 60 ° C. at a ratio of 4: 1 and H ₂ SO ₄ + H
₂ O ₂ solution (H ₂ SO ₄ : H ₂ O ₂ = 1: 1: 1 liquid temperature 80
C.) and HF (10%) solution alternately three times to wash, and finally rinsed with pure water. After the cleaning, a thermal oxide film was formed to about 1 μm on the one-way polished substrate under the conditions shown in Table 10 using a heat treatment apparatus. And the thermal oxide film is HF 10%
Removed by the solution.

Using this substrate, a 3C-SiC film was formed on the substrate. The growth of 3C-SiC is divided into a carbonization step of the substrate surface and a 3C-SiC growth step by alternate supply of a source gas. The detailed conditions of the carbonization step were the same as in Table 1, and the detailed conditions of the 3C-SiC growth step were the same as in Table 5. Center line average roughness of Si (001) plane and 3C-Si
Table 14 shows the relationship between the internal stress of C and the density of the antiphase interface defect.

[0071]

[Table 14]

When the center line average roughness is 3 nm or less, the internal stress is high and the surface defect density is high. Center line average roughness 3nm
When the thickness is in the range of １００100 nm, the internal stress is reduced and the surface defect density is eliminated. When the center line average roughness exceeds 100 nm, the surface defect density tends to increase. Also, S
The etch pit density and twin density of 3C-SiC grown on the undulating substrate with the center line average roughness of the i (001) plane controlled to 30 to 50 nm were determined as follows. 3C-S
After exposing the iC to molten KOH (500 ° C., 5 minutes), the surface was observed with an optical microscope. As a result, the number of etch pits corresponding to stacking fault density was 1,683 on the entire surface of 6 inches, and the density was 9.52. / Cm ² . Furthermore, 3C-S
Pole observation of the X-ray diffraction rocking curve (XRD) with respect to the iC <111> orientation was performed, and {11} corresponding to the twin plane was observed.
The twin density was calculated from the signal intensity ratio of the 5-plane orientation and the signal intensity of the normal single-crystal plane {111} plane. As a result, the twin density was 4 × 10 ⁻⁴ Vol. %. It can be said that the effect of the present invention was exhibited by providing the undulations on the Si (001) plane and controlling the center line average roughness to 3 nm to 100 nm. In addition, both substrates,
As a result of electron microscopic observation, as shown in FIG. 4, the substrate has a plurality of undulations extending substantially parallel to the substrate surface, and the slopes are adjacent to each other in a cross section orthogonal to the direction in which the undulations extend. The shape of the portion to be curved was curved. Further, the average slope of the undulating slope was 3 to 5 °.

Although the present embodiment was performed on the Si (001) plane, the Si (111) plane and the hexagonal silicon carbide (1, 1, -2,
0) and hexagonal silicon carbide (0,0,0,1) have been confirmed to provide similar results.

Example 7 An attempt was made to reduce the distortion of 3C-SiC by providing undulations on the front and back surfaces of a Si (001) substrate having a diameter of 6 inches. The undulations were formed by polishing under the conditions shown in Table 9. The center line average roughness was about 50 nm for both the front and back surfaces. 3C-SiC was grown on this substrate. 3C-SiC is grown by a carbonization step on the substrate surface and 3C-S by alternately supplying a source gas.
It is divided into iC growth steps. The detailed conditions of the carbonization step were the same as in Table 1, and the detailed conditions of the 3C-SiC growth step were the same as in Table 5. The grown 3C-SiC internal stress is
A very low stress of 10 MPa was obtained in the direction of compression. The stresses generated on the front and back surfaces were canceled out, and the warpage and strain became small, and good 3C-SiC growth was brought about. It can be said that the effect of forming undulations on the front and back surfaces of the substrate was obtained. Although the present embodiment was performed on the Si (100) plane, the Si (111) plane, hexagonal silicon carbide (1, 1, -2, 0), and hexagonal silicon carbide (0,
It has been confirmed that similar results can be obtained with (0, 0, 1).

Example 8 In the above example, it was found that high quality 3C-SiC can be obtained by forming undulations having a predetermined shape on the substrate surface. In this embodiment, a method for forming an undulating shape by dry etching will be described. First, a quartz mask as shown in FIG. 5 was manufactured. The line and space patterns provided on the mask of this embodiment are spaced at 100 μm intervals. The long side of the window of the mask is arranged parallel to <110> of the silicon substrate.
Then, the distance between the silicon substrate and the mask was set to 1 mm (FIG. 6). This is because when the interval is set to 0, a rectangular line & space pattern is transferred to the silicon substrate. The RIE apparatus was used for dry etching. CF _{4 for} etching
The a 40sccm and O ₂ was used 10sccm of gas. R
The power of the F power source is set to 250W and the degree of vacuum between the electrodes is set to 8P.
Etching was performed for 4 hours as a (Table 15). As a result, the silicon substrate surface has a period of 200 μm, a depth of 8 μm (center line average roughness of 60 nm to 100 nm), and a slope of 3 to 5 °.
The stable wavy undulation was transferred. With the 3C-SiC formed on the present substrate, good results were obtained in which the surface defect density was 0 to 1 / cm ² . Also, RIE (Reactive Ion Etc
The etch pit density and twin density of 3C-SiC grown on the corrugated substrate processed by hing (reactive ion etching) were determined as follows. 3C-SiC melted KOH
(500 ° C., 5 minutes), the surface was observed with an optical microscope. The number of etch pits corresponding to the stacking fault density was 1,290 on the entire surface of 6 inches, and the density was 7.30.
/ Cm ² . Further, pole observation of the X-ray diffraction rocking curve (XRD) with respect to the 3C-SiC <111> direction was performed, and the signal intensity of the {115} plane direction corresponding to the twin plane and the signal intensity of the normal single crystal plane {111} plane were compared. Twin density was calculated from the signal intensity ratio. As a result, the twin density was 4 × 10 ⁻⁴ Vol. %.

[0076]

[Table 15]

Although a quartz mask is used in the embodiment, the material is not limited to this. Line and space is 1
Although the interval is set to 00 μm, it can be set arbitrarily to 10 to 1000 μm. Opening a thinner window may cause a problem in the strength of the mask. However, it is necessary to secure the mask strength by setting the distance between the line and the space to 1: 2 or 1: 3, and to perform dry etching a plurality of times while shifting the position of the mask. High density undulations may be formed. Although the distance between the mask and the pattern transfer substrate is set to 1 mm, the distance is not necessarily limited to the purpose of making the transfer pattern wavy. It is sufficient that the pattern to be transferred has a distance such that the pattern becomes wavy. By making the cross section of the window of the mask trapezoidal, it is possible to transfer the wavy undulation by etching.

Example 9 When the surface shape of the manufactured undulation substrate is saw-shaped, defects such as etch pits occur occasionally in the steep concave portions, and the defects propagate to the surface as shown in FIG. Is a problem. Therefore, an attempt was made to suppress the occurrence of defects by making the surface shape of the undulation a waveform and reducing the sharp recesses. The saw-shaped undulation was produced by one-way polishing. (The method is the same as the one-way polishing in the example, but does not perform the final oxidation treatment.) On the surface of the Si (001) substrate having a diameter of 6 inches, <1 is applied.
A method in which polishing is performed in parallel with the <10> direction, and is performed in the <110> direction.
An attempt was made to fabricate an undulating substrate parallel to the direction. For polishing, a commercially available diamond slurry having a diameter of about 15 μm (manufactured by Engis: High Press) and a commercially available polishing cloth (manufactured by Engis: M414) were used (Table 9). The diamond slurry was uniformly infiltrated on the cloth, a Si (001) substrate was placed on the pad, and 0.2 kg / cm ²
<11 while applying a pressure of
One-way polishing was performed by reciprocating 300 times a distance of about 20 cm above the cloth in parallel with the 0> direction. Innumerable polishing scratches (scratches) parallel to the <110> direction were formed on the surface of the Si (001) substrate.

A Si (001) -based one-way polished
Since abrasive grains are attached to the plate surface, NH_FourOH
+ H_TwoO_Two+ H_TwoO mixed solution (NH_FourOH: H_TwoO_Two: H_TwoO
= 4: 4: 1 at a liquid temperature of 60 ° C.)_TwoS
O_Four+ H_TwoO_TwoSolution (H_TwoSO_Four: H _TwoO_Two= 1: 1 ratio
(Liquid temperature 80 ° C) and HF (10%) solution alternately three times
And rinsed, and finally rinsed with pure water. Surface just after polishing
Has a very sharp undulation shape (saw shape)
(Fig. 7 (b)). The undulation of the wave shape is one
Saw-shaped undulation made by directional polishing
After that, thermal oxidation treatment is performed on the undulation surface
As a result, the surface was relieved into a waveform. Ange after polishing
After cleaning the substrate, the heat treatment device was used to clean the substrate.
Under the condition shown in FIG.
μm was formed. Then, the thermal oxide film is formed with a 10% HF solution.
Removed. With just polishing, the substrate surface was obtained
Many small irregularities and defects other than rough undulations remain, and
It is difficult to use as a substrate. However, thermal oxide film is about 1μm
After removing the oxide film again, the substrate surface
000Å etching, very fine irregularities are removed
Obtaining a smooth undulation surface
did it. Looking at the wavy section, the size of the wavy irregularities is unstable
Irregular but dense. At least (001) plane
Is 10% or less. It is always undulating. Average
And a center line average roughness of 20 nm. Groove depth is 30-50
nm and the width were about 0.5 to 1.5 μm. The slope is 3
５5 °. FIG. 4 shows a typical AFM image.

Using this substrate, a 3C-SiC film was formed on the substrate. The growth of 3C-SiC is divided into a carbonization step of the substrate surface and a 3C-SiC growth step by alternate supply of a source gas. The detailed conditions of the carbonization step were the same as in Table 1, and the detailed conditions of the 3C-SiC growth step were the same as in Table 5. The corrugated undulation was performed by forming a saw-shaped undulation by one-way polishing, and then performing a thermal oxidation treatment on the undulated surface to relax the surface into a corrugated shape. A corrugated undulation substrate was fabricated, and the steep concave portions were gradually improved. Also, undulation of the waveform is formed by dry etching,
A comparison was made. SiC on corrugated undulation substrate
As a result, no defect generated in a steep concave portion like SiC on a saw-shaped undulation substrate was observed. (FIG. 7 (c)) Table shows the defect generation density.

[0081]

[Table 16]

Further, the pattern is formed on the waveform undulation substrate.
Increase the etch pit density and twin density of 3C-SiC
It was determined as follows. 3C-SiC is melted in KOH (500
(5 ° C for 5 minutes), and the surface was observed with an optical microscope.
At this time, the number of etch pits corresponding to the stacking fault density is 6 inches.
H 1,700 or less on the entire surface, and the density is 10 / cm ^Two
It was below. In addition, 3C-SiC <111> orientation
Observation of X-ray diffraction rocking curve (XRD)
And signal intensity of {115} plane orientation corresponding to twin plane
From the signal intensity ratio of the normal single crystal plane {111} plane orientation
The crystal density was calculated. As a result, the twin density is at the measurement limit.
4 × 10^-FourVol. %. one
On the other hand, 3C- grown on saw-shaped undulation substrate
The number of etch pits of SiC is 284,35 on the entire surface of 6 inches.
6 pieces, density 1609 / cm^TwoAnd the twin density is 6 ×
10^-3Vol. %Met. Thus, the waveform ange
Defects that occur at the substrate interface
The generation density of the slag was greatly improved. According to the invention
Then, the density of the etch pits generated on the substrate surface is reduced to 10 / c.
m^TwoIn the following, 4 × 10^-FourVol. % Or less
It becomes possible. In addition, a large surface of 6 inches in diameter
The etch pit density on the substrate surface is 10 / cm^Two
In the following, 4 × 10^-FourVol. % Or less
Can be. The present invention has been described with reference to the embodiments.
However, the present invention is not limited to the above embodiment. An example
For example, the film forming conditions and film thickness of the 3C-SiC film are not
It is not limited to. In the embodiment, a substrate having a diameter of 6 inches is used.
However, the effect of the present invention can be applied to a substrate having a diameter of 6 inches.
Not limited, for example, a diameter of 8 inches or more
Even for large-diameter substrates and small-diameter substrates less than 4 inches in diameter
Can be obtained as well.

[0083]

As described above, according to the method for manufacturing silicon carbide of the present invention, the silicon carbide layer in which the anti-phase region boundary surface is effectively reduced or eliminated and the internal stress and strain of the silicon carbide layer are reduced. A film is obtained. The silicon carbide film of the present invention
Since it has a low crystal boundary density, it has very excellent electric characteristics and is widely useful as various electronic devices.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of generation of an antiphase region boundary surface 1 and twins due to an increase in step density at a silicon carbide / silicon substrate interface.

FIG. 2 shows 3C-SiC grown on a substrate having an off angle of 4 °
Scanning electron micrograph of the film surface.

FIG. 3 shows 3C-SiC grown on a substrate having no off-angle.
Scanning electron micrograph of the film surface.

FIG. 4 is an electron micrograph of a substrate surface used in the present invention, in a cross section orthogonal to the direction in which the undulations extend, in which the shape of a portion where slopes existing on the substrate surface are adjacent to each other is curved.

FIG. 5 is a schematic view of a quartz mask used in Example 8.

FIG. 6 is an explanatory diagram showing a relationship between a silicon substrate and a mask.

FIG. 7 shows an undulation substrate (a) having a saw-shaped surface shape, a substrate (b) having a very sharp undulation shape, and an undulation substrate (c) having a corrugated surface shape obtained in Example 9. 3C-Si grown on)
Scanning electron micrograph of the surface of the C film.

Continued on the front page (72) Inventor Kuniaki Yagi 2-7-5 Nakaochiai, Shinjuku-ku, Tokyo F-term in Hoya Corporation (reference) 4G077 AA03 AB01 BE08 CG01 DB13 ED04 ED05 ED06 TK04 TK06 5F045 AA03 AA06 AA11 AC05 AC07 BB12 BB13 GH02 HA03

Claims (12)

[Claims] In a method of manufacturing silicon carbide for depositing silicon carbide on at least a part of the surface of a substrate, the surface of the substrate on which the silicon carbide is deposited has a plurality of undulations extending substantially in parallel, and the undulations are centered. The linear average roughness is in the range of 3 to 1000 nm, and the slope of the undulating slope is 1 ° to 54.7.
°, and a cross section orthogonal to the direction in which the undulations extend, the shape of the portion where the slopes are adjacent to each other is curved. 2. A method of manufacturing silicon carbide for depositing silicon carbide on at least a part of the surface of a substrate, wherein the surface of the substrate on which the silicon carbide is deposited has a plurality of undulations extending substantially in parallel, and the undulations are centered. The linear average roughness is in the range of 3 to 1000 nm, and the slope of the undulating slope is 1 ° to 54.7.
°, the substrate is silicon or silicon carbide, the normal axis of the surface of which is in the <001> direction, and the ratio of the {001} plane to the substrate surface area does not exceed 10%. Method for producing silicon carbide. 3. A method of manufacturing silicon carbide for depositing silicon carbide on at least a part of the surface of a substrate, wherein the surface of the substrate on which the silicon carbide is deposited has a plurality of undulations extending substantially in parallel, and the undulations are centered. The linear average roughness is in the range of 3 to 1000 nm, and the slope of the undulating slope is 1 ° to 54.7.
°, the substrate is silicon or cubic silicon carbide, the normal axis of the surface of which is in the <111> direction, and the ratio of the {111} plane occupying the area of the substrate surface does not exceed 3%. A method for producing silicon carbide, comprising: 4. A method of manufacturing silicon carbide for depositing silicon carbide on at least a part of a surface of a substrate, wherein the surface of the substrate on which silicon carbide is deposited has a plurality of undulations extending substantially in parallel, and the undulations are centered. The linear average roughness is in the range of 3 to 1000 nm, and the slope of the undulating slope is 1 ° to 54.7.
°, the substrate is hexagonal silicon carbide, the normal axis of the surface of which is in the <1,1, −2,0> direction, and {1,1, −2, The ratio of 0｝ plane is 10
% Of silicon carbide. 5. A method of manufacturing silicon carbide for depositing silicon carbide on at least a part of a surface of a substrate, wherein the surface of the substrate on which the silicon carbide is deposited has a plurality of undulations extending substantially in parallel, and the undulations are centered. The linear average roughness is in the range of 3 to 1000 nm, and the slope of the undulating slope is 1 ° to 54.7.
°, the substrate is hexagonal silicon carbide, the normal axis of the surface of which is in the <0,0,0,1> direction, and occupies {0,0,0,1} in the area of the substrate surface. A method for producing silicon carbide, wherein a ratio of a surface does not exceed 3%. 6. The production method according to claim 1, wherein the precipitation of silicon carbide is performed from a gas phase or a liquid phase. 7. The manufacturing method according to claim 2, wherein in a cross section orthogonal to the direction in which the undulations of the substrate surface extend, the shape of a portion where the slopes are adjacent to each other is curved. 8. Single-crystal silicon carbide having a planar defect density of 1000 / cm ² or less. 9. Single-crystal silicon carbide having an internal stress of 100 MPa or less. 10. Single-crystal silicon carbide having a planar defect density of 1000 / cm ² or less and an internal stress of 100 MPa or less. 11. An etch pit density of 10 / cm ² or less and a twin density of 4 × 10 ⁻⁴ Vol. % Or less, single-crystal silicon carbide. 12. The method according to claim 1, wherein the silicon carbide is deposited by epitaxial growth while inheriting the crystallinity of the substrate surface. 13. The method for producing single-crystal silicon carbide according to item 10.