• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A single crystal of SiC having at least one orientation range where a base plane dislocation has a high linearity and is oriented to three crystallographically equivalent. <11 -20> directions, and a SiC wafer and a semiconductor device made from the single crystal of SiC. The single crystal of SiC can be produced by using as a seed crystal in which the displacement angle on an upper part of a {0001} plane side is small and the displacement angle on a downstream side in the displacement direction is large and growing another crystal on the seed crystal.
    公开号:SE1351437A1
    申请号:SE1351437
    申请日:2012-05-16
    公开日:2013-12-03
    发明作者:Itaru Gunjishima；Yasushi Urakami；Ayumu Adachi
    申请人:Denso Corp；
    IPC主号:
    专利说明:

    [5] In particular, a base plane dislocation bends highly in a {0001} -p | an by interleaving between dislocations. In the case where a base plane dislocation bends in this manner, it sometimes happens when a substrate (usually cut to form an offset angle of 4 ° to 8 ° to a {0001} -p | an to form an epitaxial film) for producing a device is taken from a single crystal, that a base plane dislocation can be exposed at a plurality of points on the surface of the substrate (refer to Fig. 15). As a result, the dislocation continues from the plurality of points as the epitaxial film is formed (non-Patent Literature 2 and 3).
    [6] A line cannot be a straight line so that the line intersects a plane at several points. It would be better for a line to be rectilinear to reduce the number of intersections.
    [7] At the same time, as described in Patent Literature 1, it is possible to reduce the dislocation density of a crystal by using a method (RAF method) in which a c-plane growth is performed after a repeated a-plane growth. Furthermore, in Non-Patent Literature 5, it is described that a base plane dislocation tends to be oriented by the RAF method. In the literature, however, a measure to assess the existence of orientation and linearity is not obvious. Furthermore, a dislocation density is still high, intertwining with a shear defect occurs frequently. Although the tendency of orientation is partially recognized in each dislocation, the linearity is not strong and many curved dividers occur. In addition, such an area is limited to an area on the order of millimeters.
    [10] A problem to be solved by the present invention is to provide a single crystal of SiC having a highly linear base plane dislocation which is strongly oriented to a stable <11-20> direction, and a SiC wafer and a semiconductor device made from such a single crystal of Sic.
    [11] To solve the above problems, a single crystal of SiC according to the present invention has the following configuration: (1) the single crystal of SiC has at least one orientation area where a base plane dislocation has a high linearity and is oriented to three crystallographically equivalent <11-20> directions ; and (2) the "orientation area" refers to an area assessed by the following methods, (a) a disk having the surface almost parallel to a {0001} plane is cut out of the single crystal of SiC, (b) X-ray topography measurement by transmission arrangement is applied to the disk and X-ray topography images three crystallographically equivalent {1-100} planar diffractions are photographed, (c) each of the three X-ray topography images is converted into a digital image obtained by quantifying the brightness of each point in the image and each of the three digital images is divided into a square measuring area where the length of each side is 10 in 0.1 mm, (d) two-dimensional Fourier transform processing is applied to each of the digital images in the three measuring ranges corresponding to an identical area on the disk and a power spectrum (spectrum of the amplitude A of a Fourier coefficient) obtained, (e) each of the three power spectra is converted into a polar coordinate function and a function Am, (G) of angular depending (direction dependent) of an average amplitude A is obtained (0 ° s G s 180 °), (f) an integrated value A'ave_ (G) of the three Aavi, (G) is shown in a graph (x-axis: G, y-axis: Aäve.) And the ratio of a peak value Åäve. (Gi) to a background B.G. (Gi) (= Ååve. (Gi) / B.G.
    [12] A SiC wafer according to the present invention comprises a wafer cut almost parallel to a {0001} plane from the single crystal of SiC according to the present invention.
    [13] In the case where a single crystal of SiC is grown on a c-plane, by using a seed crystal in which the displacement angle of a surface satisfies specific conditions, it is possible to obtain the single crystal of SiC having a highly linear base plane dislocation which is strongly oriented to a stable <11-20> direction.
    [14] Fig. 1 is a schematic illustration of a Lang method (transmission arrangement topography); Fig. 2A is a schematic illustration showing the crystal plane of a hexagonal system; Fig. 2B is a schematic illustration showing the crystal orientation of a hexagonal system; Fig. 3A is an example of a digitized X-ray topography image (base plane dislocation image) (upper figure) and a schematic illustration of the crystal orientation (lower figure); Fig. 3B is a power spectrum (spectrum of the amplitude A of a Fourier coefficient) obtained by applying two-dimensional Fourier transform to the digital image in Fig. 3A; Fig. 3C is a graph showing the angular dependence of an average amplitude; Figs. 4A to 4K are schematic illustrations for explaining two-dimensional Fourier transform of an image; Fig. 4A is a digital image and Figs. 4B to 4K are sinusoidal waveforms constituting the digital image of Fig. 4A; Fig. 5A is a power spectrum obtained by Fourier transform; Fig. 5B is an example of sinusoidal waveforms at various points; Fig. 6A is a sectional view of a seed crystal of SiC; Fig. 6B is a sectional view of a single crystal of SiC growth using the seed crystal of SiC shown in Fig. 6A;
    [15] Fig. 7A is an image ((-1010) planar diffraction) in a measuring area of 10 mm square extracted from the center of an X-ray topography image of a single crystal obtained in Example 1; Fig. 7B is a power spectrum (spectrum of the amplitude A of a Fourier coefficient) obtained by applying Fourier transform to the X-ray topography image in Fig. 7A; Fig. 7C is a graph showing the G-angle dependence of an average amplitude Aaw obtained from the power spectrum of Fig. 7B; Fig. 8A is an image ((1-100) planar diffraction)) in a measuring area of 10 mm square extracted from the center of an X-ray topography image of a single crystal obtained in Example 1; Fig. 8B is a power spectrum obtained by applying the Fourier transform to the X-ray topography image of Fig. 8A; Fig. 8C is a graph showing the G-angle dependence of an average amplitude Am obtained from the power spectrum of Fig. 8B; Fig. 9A is an image ((01-10-plane diffraction) in a measuring area of 10 mm square extracted from the center of an X-ray topography image of a single crystal obtained in Example 1; Fig. 9B is a power spectrum obtained by applying Fourier transform to the X-ray topography image in Figs. Fig. 9C is a graph showing the G-angle dependence of a mean amplitude Am obtained from the power spectrum of Fig. 9B; Figs. 10A to 10C are graphs showing the G-angle dependence of mean amplitudes Am shown in Figs. Figs. 7C, 8C, and 9C; Fig. 10D is the integrated value A'ave_ of Figs. 10A to 10C; Fig. 11 is a graph showing an example of a method for calculating an Agve (GQ / BG (6i); Fig. 12A is an X-ray topography image and an orientation intensity at an area other than a facet; Fig. 12B is an X-ray topography image and an orientation intensity at an area near a facet;
    [16] Fig. 13A is an image ((-1010) planar diffraction) in a measuring area of 10 mm square extracted from an X-ray topography image of a single crystal obtained in Comparative Example 1; Fig. 13B is a power spectrum obtained by applying the Fourier transform to the X-ray topography image of Fig. 13A; Fig. 13C is a graph showing the G-angle dependence of a mean amplitude Aave. obtained from the power spectrum of Fig. 13B; Fig. 14 is a graph showing the measurement range size dependence on the orientation intensities B of single crystals obtained in Example 1 and Comparative Example 1; Fig. 15 is a schematic illustration showing the state of generating a plurality of edge dislocations from a curved base plane dislocation; Fig. 16 is a schematic illustration as the pointer state for generating an error stack due to the decay of a base plane dislocation to partial dislocations; Fig. 17 is a schematic illustration showing the state of generating an edge dislocation from a rectilinear base plane dislocation; and Fig. 18 is a schematic illustration of a base plane dislocation stabilized in the <11-20> direction.
    [17] An embodiment of the invention is explained in detail below. [1. A single crystal of SiC] A single crystal of SiC according to the present invention has the following configuration: (1) the single crystal of SiC has at least one orientation area where a base plane dislocation has a high linearity and is oriented to three crystallographically equivalent <11-20> directions; and (2) the "orientation area" refers to an area assessed by the following methods, (a) a disk having the surface almost parallel to a {0001} plane is cut out of the single crystal of SiC, (b) X-ray topography measurement by transmission arrangement; applied to the disk and X-ray topography images corresponding to three crystallographically equivalent {1-100} planar diffractions are photographed, (c) each of the three X-ray topography images is converted to a digital image obtained by quantifying the brightness of each point in the image and each of the three digital images is divided into a square measuring range where the length of each side is 10 in 0.1 mm, (d) two-dimensional Fourier transform processing is applied to each of the digital images in the three measuring ranges corresponding to an identical area on the disk and a power spectrum (spectrum of the amplitude A of a Fourier coefficient) obtained, (e) each of the three power spectra is converted into a polar coordinate function and a function Am (6) of angular (direction-dependent) of an average amplitude A is obtained (0 ° s 6 s 180 °), (f) an integrated value A'ave_ (6) of the three Aave (6) is shown in a graph (x-axis: 6, y -axis: Aëve.) and the ratio of a peak value Aïave. (Gi) to a background B.G. (Gi) (= Aåve. (G,) / B.G.
    [18] [1.118] [1.1. Orientation area] An “orientation area” refers to an area where a base plane dislocation has a high linearity and is oriented to three crystallographically equivalent <11-20> directions. Whether the linearity is high or not and a base plane dislocation is strongly oriented can be judged by calculating an A'a , e_ (6i) / B.G. (GJ ratio from an X-ray topography image. The details of the assessment method are described later. A single crystal of SiC need only have at least one such orientation range in its interior.
    [19] In the case where a single crystal of SiC is grown on a c-plane, an offset substrate is generally used as the seed crystal. A c-plane facet as a growth peak is located at the end of a displaced substrate on the upstream side in the displacement direction. To suppress the emergence of heterogeneous polytypes, a screw dislocation that functions to take over the polytype of a seed crystal in a growth direction needs to be in a c-plane facet. For example, as a method of introducing a screw dislocation into a c-plasma facet, there is a method of introducing a screw dislocation generating region at one end of a seed crystal on the upstream side in an offset direction.
    [20] In contrast, by using a method described later, it is possible to obtain a single crystal of SiC having at least one orientation region present in a region where a facet mark is excluded. An area where a facet mark is present corresponds to a screw dislocation generating area and is thus in itself unsuitable prefabrication of a device. For this reason, it is desirable that an orientation area exist in an area where a facet mark does not exist.
    [21] Furthermore, by using the method described later, it is possible to obtain a single crystal of SiC having a higher orientation intensity B as a distance from a facet mark increases.
    [22] [1.222] [1.2. Area ratio of orientation area] "Area ratio of an orientation area (%)" refers to the ratio of the sum (S) of the areas of orientation areas to the sum (S0) of the areas of measurement areas (= Sx100 / S0) included in a slice cut almost parallel to a {0001} plane from a single crystal of SiC.
    [23] [1.323] [1.3. Orientation intensity B] An "Orientation intensity B" refers to the mean of three A'a ,, e_ (0i) / B.G. (Gi) - the ratios (i = 1 to 3) corresponding to three crystallographically equivalent <1-100> directions. It turns out that, when an orientation intensity B increases, a base plane dislocation has a higher linearity and a stronger orientation in the <11-20> direction.
    [24] 10 15 20 25 30 35 10 [1.4. Error Stacking] “Not including an error stacking” means that a flat projected plane defect area is not included in an X-ray topography image corresponding to {1-100} plane diffraction.
    [25] [2. Orientation area assessment method] An "orientation area" is assessed by the following procedures. [2.1. Sample preparation: method (a)] A disk with the surface almost parallel to a {O0O1} plane is first cut from a single crystal of SiC.
    [26] [2.226]. X-ray topography: method (b)] 10 15 20 25 30 35 11 Next, X-ray topography measurement is applied by transmission arrangement to the disk and X-ray topography images corresponding to three crystallographically equivalent {1-100} planar diffractions are photographed.
    [27] A Lang method (transmission arrangement topography) is a means of enabling: photographing a defective distribution of an entire disk; and to be used for quality inspection of a disc. The Lang method includes a method of using a large-scale synchrotron radiation facility and a method of using a small-scale laboratory-level X-ray generator. The measurement described in the present invention can be performed by any of the methods. A general technique applied to the latter method is described here.
    [28] As a method for detecting a dislocation having a Burger vector in a {0001} i-plane direction, {1 1-20} planar diffraction is also generally used. However, due to the {11-20} plane diffraction, an error stack in a {0001} plane cannot be detected.
    [29] [2.329] [2.3. Digitization and image preprocessing of topographic image: method (c)] Then each of the three X-ray topographic images is converted into a digital image obtained by quantifying the brightness of each point in the image and each of the three digital images is divided into a measuring area having a size of 10 and 0.1 mm.
    [30] (1) A topography image obtained on a film or a nuclear emulsion plate is digitized with a scanner or the like. The scanning conditions for digitization are shown below: Resolution: 512 pixels / cm or more the actual size of a movie, and Execution (mode: gray). (2) A digitized topography image (digital image) is divided into a square measuring area where the length of each side is 10 in 0.1 mm. When the size of a disc is relatively large, the surface of the disc is divided into squares and a number of measuring areas are taken out. In general, if a measuring range is too small, the measurement is limited and the result corresponding to an average structure of a dislocation in a crystal is not obtained. On the other hand, if a measuring area is too large, a base plane dislocation image is too thin and unclear and an orientation is difficult to examine. (3) The gray level of a digital image is adjusted to enable a clear base plane dislocation image to be obtained. Specifically, the part of a base plane dislocation is adjusted to darkest (black) and a part other than a dislocation is adjusted to lightest (white). (4) The number of pixels on a page is adjusted to 512 pixels. If the number of pixels is too small, a clear base plane dislocation image is not obtained. However, if the number of pixels is too large, Fourier transform processing will be slow. 10 15 20 25 30 35 13
    [31] [2.431]. Image analysis: method (d)] Next, two-dimensional Fourier transform processing is applied to each of the three digital images in the measuring range corresponding to an identical area on a disk and a power spectrum (spectrum of the amplitude A of a Fourier coefficient) is obtained.
    [32] [2.532] [2.5. Calculation of A'aVe_ (6i) /B.G. (6i) ratio: methods (e) to (g)] Then each of the three power spectra is converted into a polar coordinate function and an Aave_ (6) function of angular (directional) of an average amplitude A is obtained (0 ° s 6 S 180 °) (procedure (e)). In the conversion to a polar coordinate function, the following processing is applied. In a power spectrum, an average amplitude A at an angle i in the counterclockwise direction from 0 ° of the x-axis is calculated. That is, 6 is evenly distributed in the range of 0 ° to 180 °, and the average value of the amplitudes of Fourier coefficients from the center to the end of a power spectrum is obtained at each angle.
    [33] Fig. 3A shows an example of a digitized X-ray topography image (base plane dislocation image). A power spectrum is obtained by applying two-dimensional Fourier transform to the digital image (Fig. 3B). The power spectrum is converted to a function of polar coordinates, an average of amplitudes is obtained at an angle (direction of periodicity), and a function AaVe_ (G) of angle-dependent (direction-dependent) of the mean amplitude is obtained (Fig. 3c). The conversion is applied to each of the base plane dislocation images obtained under the three diffraction conditions and the function Aave_ (G) of the angular dependence of the three obtained average amplitudes is integrated.
    [34] In the graph of an integrated value A'ave_ (G), the ratio of a peak value A'i, ive_ (Gi) to a background B.G. (Gi) (= A'a , e_ (Gi) / B.G. (Gi) ratio) for each of the three Gi (i = 1 to 3) corresponding to the three <1-100> directions.
    [35] When a clear peak is displayed at each of the three Gi (i = 1 to 3) corresponding <1-100> directions by applying appropriate image processing, the area of the disk corresponding to the measuring areas is judged as an "orientation area". A "clear peak" means that an A'aVe_ (Gi) / B.G. (Gi) ratio (i = 1 to 3) is 1.1 or more.
    [36] [2.6. Detailed Explanation of Two-Dimensional Fourier Transform] A wave, such as an acoustic wave, an electromagnetic wave, or a seismic wave can be expressed by the combination of trigonometric waves (sin, cos) that have different magnitudes (amplitudes), frequencies, and phases. Similarly, as shown in Figs. 4A to 4K, the image shown in Fig. 4A can also be expressed by superposition of the trigonometric waves (Figs. 4B to 4K) with periodicity in different directions and different frequencies.
    [37] Fourier transform F (kX, ky) of an image f (x, y) having a size of NxN pixels is represented by the following expression (1). Here, f is the brightness at a coordinate (x, y) and can be obtained by representing a digital image by means of a bitmap and extracting the information about the brightness at each point from the image data. k is a frequency.
    [38] A Fourier coefficient F (kX, ky) calculated by expression (1) is generally a complex number and is represented as a point of F (kx, ky) = a + ib on a complex plane. On a complex plane, an angle formed between a line connecting a starting point with a + ib and the real number axis refers to the phase of the trigonometric function of the frequency having a cycle from the center of an image to the direction of a coordinate (x, y) . / (a2 + b2) which is the distance from the starting point to a + ib represents the amplitude A of the trigonometric function wave.
    [39] For example, when two-dimensional Fourier transform is applied to an image of regularly-ordered particles or the like and a power spectrum is obtained, a clear point is displayed and the contribution of a specific frequency in a specific periodicity direction can be remarkably detected. At the same time, two-dimensional Fourier transform can be applied not only to an image having regularity but also to the examination of orientation of a fiber.
    [40] Here, an amplitude A of a power spectrum at each coordinate is represented by a function A (6, r) of polar coordinates (Fig. 3B). Here, 6 is an angle formed by a line connecting the center of a spectrum to the coordinates thereof and a line in the horizontal direction. Furthermore, r represents a distance from the center of the spectrum to the coordinates thereof.
    [41] As a method for obtaining the orientation intensity, there is also a method of drawing Aave_ (6) as a polar coordinate graph, approximating a curve by means of an ellipse and obtaining a long axis / short axis ratio (Reference Literature 1 to 3). However, in the Fourier transform of a base plane dislocation image obtained in the present invention, Aave_ (6) shows a relatively steep maximum value and is not uniaxial orientation and thus ellipse approximation which is possible in the case of ordinary fiber orientation cannot be applied.
    [42] Therefore, in the present invention, with respect to AaVe_ (6) obtained by two-dimensional Fourier transform, the orientation of a base plane dislocation is evaluated by the following specific procedures shown below: (1) with respect to three crystallographically equivalent {1-100} - planes having different angles in a {0001} -p | an X-ray topography is applied by {1-100} -plane diffraction and three X-ray topography images of a base plane dislocation are obtained. From the X-ray topography images, three AaVe_ (6) corresponding to the {1-100} planar diffraction are obtained, (2) the integrated value A'aVe_ (6) of the three AaVe_ (6) obtained by Fourier transform is obtained, and (3) when the integrated Å 'ave. (6) is plotted, in the case when A'aVe_ (9) shows a clear peak in each of the three 6 corresponding <1-100> directions, the base plane dislocation is judged to be oriented to the <11-20> direction.
    [43] [2.7. Use Two-Dimensional Fourier Transform Software] In the present invention, to apply Fourier transform to a base plane dislocation image, Fiber Orientation Analysis Ver. 8.13 developed by the authors of Reference Literature 1 to 3. The Fourier transform software performs the processing of extracting information regarding the brightness of each point from the image data, applying Fourier transform processing, and obtaining a power spectrum and AaVe_ (6). Detailed procedures are described in Reference Literature 1 to 3 and Reference URL 1. To apply Fourier transform processing to an image with the software, the image is converted to a bitmap in advance to remove the numerical information of brightness. To further apply fast Fourier transform, the number of pixels on one side of an image is adjusted in advance so that it is an integral multiple of four.
    [44] Fourier transform processing is uniquely determined and thus any software can be used as long as the software can perform the same processing. However, the specific feature of the present software developed to evaluate orientation is to enable AaVe_ (6) to be obtained. When AaVe_ (6) cannot be obtained automatically with other software, it is necessary to use a power spectrum obtained by mapping the brightness of (x, y) coordinates and applying the same calculation in accordance with expression (2).
    [45] [345] [3. A single crystal manufacturing method of SiC] A single crystal of SiC according to the present invention can be manufactured by various methods and can be manufactured, for example, by using a seed crystal of SiC which meets the following conditions and growing a new crystal on the surface of the seed crystal. of SiC: (1) the seed crystal of SiC has a major growth plane comprising a plurality of sub-growth planes, (2) a direction (major direction) having the plurality of sub-growth planes occurring in an arbitrary direction from an upper part of a {0001} - p | an located on the main growth plane of the seed crystal of SiC towards the outer periphery of the main growth plane, and (3) when the sub-growth plane occurring from the top of the {0001} plane towards the outer periphery along the main direction is defined as a first sub-growth plane, a second sub-growth plane, -----, and a nth sub-growth plane (n 2 2) in sequence, the relationship Sk <Gm m between the displacement angle Bk of the kth sub-growth plane (1 so-called n-1) and the displacement angle Gm of the (k + 1) :th sub-growth plane.
    [46] Here, a "major growth plane" refers to a plane that forms part of exposed planes of a seed crystal of SiC and has a component of a crucible center axis / raw material direction in its normal vector 'a'. A "crucible center axis / raw material direction" in a sublimation precipitation method is a direction from a seed crystal of SiC to a raw material and a direction parallel to the center axis of a crucible. In other words, a "crucible center axis / raw material direction" represents a macro growth direction of a single crystal of SiC and generally refers to a direction perpendicular to the bottom plane of a seed crystal of SiC or a surface of a seed crystal pedestal to fix the seed crystal of SiC.
    [47] Fig. 6A shows an example of a sectional view of a seed crystal of SiC satisfying the above conditions. Fig. 6B shows a sectional view of a single crystal of SiC made using the seed crystal 12b of SiC.
    [48] With respect to the X1Xz plane and the XsXß plane, the respective normal vectors thereof are perpendicular to the vector 'q'. Furthermore, the X1X6 plane is a plane that touches a crucible or a seed crystal pedestal (not shown in the figure). Accordingly, the main growth plane includes the X2X3 plane, the X3X4 plane and the X4X5 plane. Furthermore, the direction from point X3 of the uppermost part of the {0001} plane to point X5 at the outer periphery of the main growth plane is a direction (main direction) having a plurality of sub-growth planes. In the sub-growth plane located along the main direction, the sub-growth plane comprising the upper part of the {0001} plane is the X3X4 plane and the plane is the first sub-growth plane. The second sub-growth plane is the X4X5 plane and has a ratio of 01 <62.
    [49] As shown in Fig. 6A, by partially changing the displacement angle of a major growth plane of a seed crystal 12b of SiC and growing a single crystal of SiC using it, it is possible to suppress the leakage of a screw dislocation or a base plane edge dislocation and control a screw dislocation density distribution in a growth crystal.
    [50] Furthermore, in a seed crystal 12b of SiC, inclined planes X2X3 and X3X4 are formed so that an upper part X3 of a {0001} plane can be inside a main growth plane. Therefore, when a crystal is grown using it, as shown in Fig. 6B, even when a growth crystal expands in a radial direction, a c-plane facet is not likely to deviate from a high density screw dislocation range. As a result, it is possible to suppress the generation of heterogeneous polytype caused by the temporary reduction of a screw dislocation density.
    [51] Furthermore, when a seed crystal 12b of SiC of such a shape is cut from a single crystal growth using a plane almost perpendicular to a c-plane as the growth plane and a single crystal of SiC is grown using it, a base plane dislocation remains. in a growth crystal probably oriented in the <11-20> direction. Furthermore, it is possible to obtain a single crystal of SiC comprising an area which does not substantially comprise an error stack. This is believed to be due to the fact that a dislocation which becomes a starting point of a base plane dislocation and a screw dislocation which is converted to a fault stack are few in the seed crystal as such, a screw dislocation rarely leaks from a screw dislocation generation area formed at a seed crystal end and the interleaving screw dislocation does not occur.
    [52] [4]. SiC disk] A SiC disk according to the present invention comprises a disk cut almost parallel to a {0001} plane from a single crystal of SiC according to the present invention.
    [53] A obtained disc is used for various applications as it is or in the state of forming a thin film on a surface. For example, when a semiconductor device is fabricated using a wafer, an epitaxial film is formed on a surface of a wafer. As an epitaxial film, SiC, nitride such as GaN or the like are specifically used.
    [54] [554] [5. Semiconductor device] A semiconductor device according to the present invention comprises a device manufactured using a SiC disk according to the present invention. As a semiconductor device, it is specifically (a) an LED, or (b) a diode or a transistor for a power unit.
    [55] [655] [6. Effect of single crystal of SiC, SiC wafer, and semiconductor device] In the case where a single crystal of SiC is grown on a c-plane, by using a seed crystal in which the displacement angle of a surface meets specific conditions, it is It is possible to obtain the single crystal of SiC which has a high-linear base plane dislocation which is strongly oriented to a stable <11-20> direction.
    [56] (Example 1) [1. Sample preparation] A step of growing a single crystal of SiC on a growth plane almost parallel to a c-plane, a step of extracting a seed crystal having a growth plane almost perpendicular to both the last growth plane and the c-plane from the obtained the single crystal of SiC, and a step of growing a single crystal of SiC again using the seed crystal was repeated. A c-plane offset substrate was taken out of the obtained single crystal of SiC and processed into the mold shown in Fig. 6A. A screw dislocation generation area was formed on the XgXg plane and the X3X4 plane on the growth plane. Using it, a single crystal of SiC was made by a sublimation reprecipitation method. The resulting single crystal was cut out almost parallel (offset angle 8 °) to a {0001} surface, planing treatment and treatment to remove damaged layer was applied to the surface, thereby obtaining a disk 500 μm thick. The damaged layer was removed by CMP treatment.
    [57] [257] [2. Test method] [2.1. X-ray topography measurement] With respect to the three planes of a (-1010) plane, a (1-100) plane, and a (01-10) plane, which are crystallographically equivalent and have different plane orientations forming angles of 60 ° with each other, {1-100} planar diffraction images were measured and X-ray topography images were obtained on photosensitive films. In the obtained three X-ray topography images, base plane dislocation images were observed linearly extending in the {0O01} plane.
    [58] [2.258] [2.2. Image pretreatment] X-ray topography images were read with a scanner and thus digitized.
    [59] [2.359] [2.3. Orientation measurement by Fourier transform] The pre-processed three digital images were processed by Fiber Orientation Analysis Ver. 8.13 as Fourier transform software and a power spectrum and an Aave_ (6) were obtained for each of the three digital images. Furthermore, the Aavejß) obtained for the three images were integrated.
    [60] [360] [3. Results] Figs. 7A to 9C show the respective imaging measurement areas of 10 mm square extracted from the center of the X-ray topography images of the single crystal obtained in Example 1, power spectra thereof, and A'aVe_ (6). Figs. 7A to 7C correspond to (-1010) planar diffraction, Figs. 8A to 8C correspond to (1-100) planar diffraction, and Figs. 9A to 9C correspond to (01-10) planar diffraction, respectively. The upper direction of the figures is the offset downstream direction and is a direction that slopes from the [-1010] direction to the [-1-120] direction at an angle of several degrees. From Figs. 7A to 9C it is understood that clear lines are seen in the directions corresponding to the <1-100> direction in the power spectrum.
    [61] Fig. 10D shows the integrated value A'aVe_ (6) of the three AaVe_ (6) (Figs. 10A to 1OC) obtained in Figs. 7A to 9C. Furthermore, Fig. 11 shows an example of a method for calculating A'aV., (6i) / B.G. (GQ ratios from the integrated value A'a ,, e_ (0). 10 15 20 25 24 From Fig. 10D it is understood that a single crystal obtained in Example 1 shows clear peaks at the three 9 corresponding <1-100> directions As shown in Fig. 11, the A'ave_ (9,) / BG (Gi) ratio is 1.82 at 0, corresponding to the [-1100] direction. The GQ ratio is 1.54 at 0, corresponding to the [-1010] direction. Furthermore, A '_, Ve_ (6i) / BG (GQ ratio is 1.43 at 0, corresponding to the [0-110] direction From the results it is obtained that the base plane dislocation is oriented to three <11-20> directions.Furthermore, the orientation intensity B which is the mean value thereof is 1.60.In addition, the peak caused by the base plane dislocation in the [-1-120] direction which is the <11-20> direction that forms the smallest angle with the offset downstream direction being the largest.
    [62] Similar treatment was applied to a 12 mm square area, a 14 mm square area, a 16 mm square area, an 18 mm square area, and a 20 mm square area and the respective integrated values A'aVe, (6) were obtained. From each of the obtained integrated values A'aVe_ (0), A'ave_ (0,) / B.G. (GQ ratios at three Gi (i = 1 to 3) corresponding to the <1-100> direction and an orientation intensity B. The results are shown in Table 1.
    [63] [Table 1] L (mm) A'ave_ (6,) / B.G. (GQ ratio B 01 [-1100] 62 [-1010] 63 [0-110] 10 1.82 1.54 1.43 1.60 12 1.61 1.50 1.39 1.50 14 1, 53 1.39 1.37 1.43 16 1.34 1.34 1.41 1.37 18 1.22 1.27 1.26 1.25 20 1.12 1.29 1.13 1.18 L (mm): Length of one side of measuring range B: Orientation intensity
    [64] An X-ray topography image was divided into a plurality of 10 mm square areas and the orientation intensities were obtained in the same manner. As a result, high orientation intensities of 1.5 or more were obtained in the area ratios of 90% or more including the center area. In contrast, an orientation intensity in a screw dislocation generation range shows a low value.
    [65] (Comparative Example 1) [1. Sample preparation] A step of growing a single crystal of SiC on a growth plane almost perpendicular to a c-plane, a step of extracting a seed crystal having a growth plane almost parallel to both the last growth plane and the c-plane from the obtained the single crystal of SiC, and a step of growing a single crystal of SiC again using the seed crystal was repeated. A c-plane offset substrate was taken out from the obtained single crystal of SiC. Here, such a preparation as shown in Fig. 6A (preparation to make the displacement angle of the X3X4 plane smaller than that of the X4Xs plane) was not applied. Furthermore, a screw dislocation generation area was formed at the XzXg plane and a certain part from X3 to the offset downstream side (the part extending to X4 in Fig. 6A). A single crystal of SiC was made using the substrate displaced from the c-plane. Here, the X-ray topography of a crystal described in non-Patent Literature 5 is an X-ray topography image obtainable by the present inventors, and it is appreciated that the orientation and linearity of the base plane dislocation image is the highest and the crystal is of high quality. A wafer was prepared from the obtained single crystal by the same procedures as Example 1. [2. Test Procedure] By performing the same procedures as Example 1, A'ave_ (9i) / B.G. (Gi) - ratios at three Gi corresponding to the <1-100> direction and an orientation intensity.
    [66] [366]. Concluded] Figs. 13A to 13C show the image of a 10 mm square measuring area at a part where the orientation intensity of a base plane dislocation is highest in terms of results in the measured X-ray topography images of a single crystal obtained in Comparative Example 1, the power spectrum thereof, and AaVe_ (6). Here, Figs. 13A to 13C correspond to (0-110) -plane diffraction. As shown in Fig. 13B, in the power spectrum, no clear line appears in the directions corresponding to the <1-100> drawing.
    [67] The integrated value A'ave_ (0) shows peaks at two Gi of the [-1100] direction and the [0- 110] direction in three Gi (i = 1 to 3) corresponding to the <1-100> direction . De Agve, (0i) / B.G. (Gi) - 10 15 20 25 26 however, the conditions are relatively small. Furthermore, a clear peak is not displayed at Gi corresponding to the [- 1010] direction. Aäiie, (Gi) / B.G. (Gi) ratio is 1.18 at Gi corresponding to the [-1100] direction. A'ai, e_ (Gi) / B.G. (Gi) ratio is 1.03 at Gi corresponding to the [-1010] direction.
    [68] Similar treatment was applied to a 12 mm square area, a 14 mm square area, a 16 mm square area, an 18 mm square area, and a 20 mm square area and the respective integrated values A '«, iVe, (G) was obtained. From each of the obtained integrated values A'ave_ (G), A'ave_ (Gi) / B.G. (Gi) ratios at three Gi corresponding to the <1-100> direction and an orientation intensity B. The results are shown in Table 2.
    [69] [Table 2] L (mm) A'ave_ (Gi) / B.G. (Gi) ratio B Gi [-1100] G2 [-1010] G3 [0-110] 10 1.18 1.03 1.27 1.16 12 1.11 1.06 1.13 1.10 14 1 , 27 1.06 1.22 1.19 16 1.18 1.04 1.00 1.07 18 1.10 1.00 1.08 1.06 20 1.05 1.03 1.08 1.05 L (mm): Length of one side of measuring range B: Orientation intensity
    [70] Fig. 14 shows the dependence of the size of the measuring range on orientation intensities B in single crystals obtained in Example 1 and. Comparative Example 1. B through the y-axis, and plotting the orientation intensity B at the magnitude of each measuring range, the ratio of L to B can be approximated by a straight line in each of Example 1 and Comparative Example 1. In the case of Example 1, the linear approximate expression of y = -0.041x + 2.01. Furthermore, in the case of Comparative Example 1, the linear approximate expression of y = -0.011x + 1.27 is obtained. It is estimated that the reason why an orientation intensity B decreases when the measuring area increases is that a base plan location in an X-ray topography image becomes unclear when the measuring area increases.
    [71] Although the embodiments of the present invention have hitherto been explained in detail, the invention is not at all limited by the embodiments and may be modified variously within the scope which does not depart from the spirit of the present invention.
    [72] A single crystal of SiC according to the present invention can be used as a semiconductor material of an ultra-low power loss power device.
    权利要求:
    Claims (4)
    [1]
    A single crystal of SiC having the following configuration: (1) the single crystal of SiC has at least one orientation region where a base plane dislocation has a high linearity and is oriented to three crystallographically equivalent <11-20> directions; and (2) the "orientation area" refers to an area assessed by the following methods, (a) a disk having the surface almost parallel to a {0001} plane is cut from the single crystal of SiC; three crystallographically equivalent {1-100} planar diffractions are photographed, (c) each of the three X-ray topography images is converted into a digital image obtained by quantifying the brightness of each point in the image and each of the three digital images is divided into a square measuring area where the length of each side is 10 in 0.1 mm, (d) two-dimensional Fourier transform processing is applied to each of the digital images in the three measuring ranges corresponding to an identical area on the disk and a power spectrum (spectrum of the amplitude A of a Fourier coefficient) is obtained, (e) each of the three power spectra are converted into a polar coordinate function and a function AM, (9) of angular dependence (directional of an average amplitude A is obtained (0 ° s 6 s 180 °), (f) an integrated value A'ave_ (0) of the three Aaw, (9) is shown in a graph (x-axis: 6, y- axis: Agve) and the ratio of a peak value A'ave_ (Gi) to a background BG (Gi) (= A'ave_ (G,) / BG (GQ ratio) is calculated for each of three Gi (i = 1 to 3) corresponding to the three <1-100> directions, and (g) when all of the three A ',, Ve_ (6,) / BG (GQ ratios are 1.1 or more, the area of the disk corresponding to the three measuring ranges is judged to be an "orientation range".
    [2]
    The single crystal of SiC according to claim 1, wherein the at least one orientation region is in a region where a facet mark is excluded in the single crystal of SiC.
    [3]
    The single crystal of SiC according to claim 1, wherein the at least one orientation region is almost in the center of the single crystal of SiC.
    [4]
    The single crystal of SiC according to claim 1, wherein the single crystal of SiC has a first orientation region which has the distance L1 to a facet mark in the single crystal of SiC and a second region which has the distance Lz (> L1) to the facet mark; and 10 15 20 25 30 10. 11. 12. 29 an orientation intensity B (= means of the three Agv., (6,) / BG (GQ ratios) corresponding to the second orientation range is greater than the orientation intensity B corresponding to the first orientation range. A single crystal of SiC according to claim 1, wherein a peak value A'ave_ (Gi) corresponding to the <1-100> direction in a power spectrum reflecting the orientation of a base plane dislocation to the <11-20> direction forming the smallest angle with an offset downstream direction A single crystal of SiC according to claim 1, wherein, in the at least one disk cut out of the single crystal of SiC, the ratio of the sum (S) of the area of the orientation areas to the sum (S0) of the area of the measuring areas is (Sx100 / S0) 50% or more The single crystal of SiC according to claim 1, wherein, in the at least one orientation range, an orientation intensity is B (= average of the three A'ave_ (Gi) / BG (GQ ratios) 1,2 or mel A single crystal of SiC according to claim 1, wherein a single crystal SiC does not contain any stacking errors. A SiC wafer cut almost parallel to a {00O1} plane from the single crystal of SiC according to claim 1. A SiC wafer according to claim 9, wherein an epitaxial film is formed over a surface. A semiconductor device manufactured using the SiC disk according to claim 9. The semiconductor device according to claim 11, wherein the semiconductor device is a diode, a transistor or an LED.
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    同族专利:
    公开号 | 公开日
    CN103635615B|2016-06-01|
    WO2012157654A1|2012-11-22|
    DE112012002126B4|2021-01-21|
    KR101713006B1|2017-03-07|
    DE112012002126T5|2014-05-15|
    CN103635615A|2014-03-12|
    JP6025306B2|2016-11-16|
    JP2012240859A|2012-12-10|
    US9166008B2|2015-10-20|
    KR20140022074A|2014-02-21|
    US20140027787A1|2014-01-30|
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