JP5015480B2 - Manufacturing method of semiconductor single crystal substrate - Google Patents

Description

  The present invention relates to a method for manufacturing a high-quality semiconductor single crystal substrate, a semiconductor single crystal substrate, and a semiconductor device.

  Semiconductor single crystals widely used in various semiconductor devices are manufactured by a bulk growth method such as a pulling method from a melt or a slow cooling method. On the other hand, the epitaxial growth method is used to form a crystalline thin film with higher crystallinity or a multilayer thin film structure with a highly controlled impurity and composition on the bulk substrate manufactured in this way. It is also widely used to produce crystals belonging to sublimable or decomposable substances that do not have a melting point under pressure that can be industrially handled by ordinary mechanical equipment technology. In particular, in the latter case, a so-called heteroepitaxial growth method is widely used, in which a single crystal substrate that is industrially available, for example, by melt growth is used, and a desired crystal is epitaxially grown on the single crystal substrate.

To be specific, in recent years, in the case of a light-emitting diode or applications widely practically used in which a gallium nitride-based compound semiconductor fabrication as a semiconductor laser is represented by the general formula Al _x In _y Ga _z N (However, 0 ≦ x , Y, z ≦ 1, and a nitride material represented by x + y + z = 1), which has a different composition (x, y, z) and different impurity concentration, is used. However, Al _x In _y Ga _z N containing GaN (However, 0 ≦ x, y, with z ≦ 1, x + y + z = 1) in the case of the growth substrate crystal is high the nitrogen dissociation pressure, bulk growth It is extremely difficult. For this reason, conventionally, different crystal substrates such as sapphire, spinel, SiC or GaAs are used as the base substrate, and the epitaxial growth relies on a heteroepitaxial growth method in which an epitaxial crystal is grown on these different crystal substrates. It is a fact.

  However, in general, when such an industrially available crystal substrate is used as a base substrate, a good epitaxial growth of a gallium nitride compound semiconductor is possible due to problems such as a difference in lattice constant from the gallium nitride compound semiconductor. It was difficult. As a method for solving such a problem, there has been proposed a method of introducing a base layer on a heterogeneous substrate by epitaxial lateral overgrowth (hereinafter referred to as ELOG) (for example, Patent Document 1, Patent Document 2, Patent Document). 3 and Non-Patent Document 1).

The formation of the underlying layer by ELOG is performed by forming a mask pattern such as SiO ₂ on a heterogeneous substrate or a gallium nitride compound semiconductor grown on a heterogeneous substrate, or forming a step on the surface of the semiconductor in a predetermined pattern shape. And a desired semiconductor crystal is selectively epitaxially grown in the lateral direction.

  In general, in the case of heteroepitaxial growth on substrates having different lattice constants, a large amount of various defects such as misfit dislocations due to lattice mismatching occur, and these defects propagate in the epitaxial growth direction. When a semiconductor device is manufactured using such a defective substrate, the obtained semiconductor becomes a factor that adversely affects the operation characteristics of the device. However, in the ELOG method, a defect such as a dislocation generated near the interface with the base substrate does not propagate to the laterally grown portion on the mask, or the defect propagation is bent in the lateral direction. Since the propagation of defects to the upper part is greatly suppressed, a semiconductor single crystal substrate having good crystallinity can be obtained. By introducing such an ELOG base layer before the formation of the element structure, it becomes possible to grow a gallium nitride compound semiconductor with good crystallinity, which greatly contributes to the improvement of characteristics of various semiconductor devices. became.

  However, the formation of a gallium nitride compound semiconductor by this ELOG is, for example, a mask having a property that makes it difficult or impossible to grow a gallium nitride compound semiconductor on the surface of a gallium nitride compound semiconductor layer grown on a different substrate. After forming a gallium nitride compound semiconductor in a vertical direction (a direction perpendicular to the main surface of the substrate) with a certain film thickness substantially only from a non-mask region, Since the growth in the horizontal direction toward the upper side of the mask is performed in preference to the growth in the vertical direction, and a film is formed, a complicated process is required, so that the manufacturing cost increases and a plurality of steps are required. Yield improvement was difficult.

  As described above, according to ELOG, a mask formation process and a pattern formation process are required, and these are performed by apparatuses different from the gallium nitride compound semiconductor growth apparatus. is there. In addition, after forming a gallium nitride-based compound semiconductor layer as an underlayer for ELOG growth on a different substrate, this is taken out of the reaction vessel and provided with a mask, and then returned to the reaction vessel for ELOG growth. It is not possible to continuously form a gallium nitride compound semiconductor layer serving as a substrate for forming an element structure on a heterogeneous substrate in a reaction vessel.

  As another method, unevenness is provided in a predetermined pattern (for example, stripes) on the surface of a gallium nitride compound semiconductor formed on a heterogeneous substrate, and lateral growth of the gallium nitride compound semiconductor is performed from the side surface of the recess. However, even in this case, it is necessary to carry out a process of providing unevenness after the growth of the gallium nitride compound semiconductor, and the same problem as the above-described method occurs.

  As described above, in the conventional method for growing a gallium nitride compound semiconductor with lateral growth, a mask as described above is formed after a gallium nitride compound semiconductor layer as a base is once grown on a different substrate. In order to prevent the contamination of the gallium nitride compound semiconductor, it is necessary to remove the wafer from the reaction vessel for growing the gallium nitride compound semiconductor. So it takes time and effort.

  In order to solve such a problem, the following method is disclosed in Patent Document 3. That is, after providing a mask region and a non-mask region on the surface of a heterogeneous substrate made of a material different from that of the gallium nitride compound semiconductor, a gallium nitride compound semiconductor is selectively grown from the non-mask region, and the mask region In this method, the first gallium nitride-based compound semiconductor layer formed so as to cover the upper portion is formed to substantially enable ELOG, thereby forming a good epitaxial crystal.

  As a specific method of providing a mask region and a non-mask region on the surface of a heterogeneous substrate, a groove is partially provided on the surface of the heterogeneous substrate, and then a gallium nitride compound semiconductor is grown on the heterogeneous substrate as compared with the heterogeneous substrate. After providing a buried film made of a material difficult to etch with a thickness equal to or greater than the depth of the groove, the buried film is removed and planarized by etching to a depth at which the surface of the heterogeneous substrate not provided with the groove is exposed. A method is used in which a non-mask region where the substrate surface is exposed and a mask region where the buried film is exposed are formed. According to this method, the formation of the heterogeneous substrate for realizing the selective growth of the above-described gallium nitride-based compound semiconductor can be realized without requiring a complicated process. That is, the formation of the buried film in the groove provided in the different substrate serving as the mask region is an extremely simple process of forming the buried film on the different substrate provided with the groove and performing etch back.

In addition to the above-described conventional technique, as a simpler method, a growth suppressing material to be a mask region is formed in an island shape by a vacuum deposition method, and a good epitaxial crystal is obtained by performing ELOG using the island portion as a mask. A method is disclosed (Patent Document 4).
JP-A-11-261169 JP 2000-012976 A JP 2001-135580 A JP 2001-185498 A A. Usui, H .; Sunagawa, A .; Sakai and A.K. Yamaguchi, Jpn. J. et al. Appl. Phys. , Vol. 36, 1997, page L899

  However, in order to provide a high-performance semiconductor device such as a light-emitting device, there is a problem that the crystallinity of an epitaxial crystal substrate manufactured by the current ELOG process is not yet sufficient. From the viewpoint of providing, there is a problem that the method for forming the mask is particularly complicated, and thus the cost is high.

  An object of the present invention is to provide a semiconductor single crystal substrate manufacturing method capable of obtaining a semiconductor single crystal substrate with improved crystallinity, a high quality semiconductor single crystal substrate, and a high-performance semiconductor device using the same. There is to do.

  Another object of the present invention is to provide a semiconductor single crystal substrate manufacturing method capable of obtaining a low-cost and high-quality semiconductor single crystal substrate, an inexpensive and high-quality semiconductor single crystal substrate, and an inexpensive and high-performance using the same. Is to provide a simple semiconductor device.

According to the invention of claim 1, in a method of manufacturing a semiconductor single crystal substrate by epitaxially growing a semiconductor crystal on a sapphire substrate, a mask material having an opening is placed on the sapphire substrate, and the inside of the opening is exposed to the outside. The semiconductor crystal is grown in parallel to the surface of the sapphire substrate of the semiconductor crystal by starting epitaxial growth of the semiconductor crystal toward the surface and epitaxially growing the semiconductor crystal on the sapphire substrate along the shape of the mask material. Epitaxial growth is performed so that the area of the cross-section is gradually reduced and then gradually expanded in the process of growing from the surface of the sapphire substrate, thereby gradually narrowing the growth region during the growth of the semiconductor crystal. And at least the surface area of the semiconductor crystal is epitaxially grown. Performed until equal to the area of the surface of the sapphire substrate used in epitaxial growth, as the mask material, the method for manufacturing a semiconductor single crystal substrate, which comprises using the silica particles contained in the colloidal silica aqueous dispersion Proposed.

According to a second aspect of the present invention, there is proposed a method for manufacturing a semiconductor single crystal substrate according to the first aspect of the present invention, wherein the mask material has a circular cross section parallel to the surface of the sapphire base substrate .

According to a third aspect of the present invention, there is proposed a method for manufacturing a semiconductor single crystal substrate according to the first aspect, wherein the mask material is spherical .

According to the invention of claim 4, in the invention of claim 1 , the epitaxial crystal grown on the sapphire substrate is a sublimable or decomposable substance having no melting point at atmospheric pressure to be a Group 3-5 compound semiconductor. A method of manufacturing a semiconductor single crystal substrate, which is a crystal to which it belongs, is proposed.

According to the invention of claim 5, there is proposed a method for manufacturing a semiconductor single crystal substrate, characterized in that the epitaxial crystal is a group 3-5 nitride semiconductor in the invention of any one of claims 1-4. The

  According to the present invention, a semiconductor single crystal substrate having excellent crystallinity can be obtained more industrially at a lower cost, and a higher performance semiconductor device can be obtained by using the semiconductor single crystal substrate thus obtained. Can be manufactured.

  Hereinafter, the present invention will be described by taking as an example a semiconductor single crystal substrate by epitaxial growth of a gallium nitride based semiconductor crystal and a method for manufacturing the same, and a semiconductor light emitting device manufactured using the semiconductor single crystal substrate. Although described, the present invention is not limited to these embodiments.

  The present invention shows the best effect in a so-called heteroepitaxial growth process in which a nitride semiconductor is epitaxially grown on a heterogeneous substrate. However, a normal crystal layer of the same type is epitaxially grown using a single crystal substrate that can be easily obtained industrially. Even in the epitaxial growth process, an effect of improving crystallinity can be expected. Also in the device application, the technical concept disclosed in the present invention can be applied to a wide variety of semiconductor devices in addition to the semiconductor light emitting device.

  FIG. 1 is a process diagram for explaining an embodiment of a method for producing a semiconductor single crystal substrate according to the present invention, and an embodiment of the present invention will be described with reference to FIG. The semiconductor single crystal substrate manufactured as described below is particularly suitable for use in manufacturing a light emitting diode element.

First, as shown in FIG. 1A, a base substrate (growth substrate) 1 is prepared. As the base substrate 1, a substrate made of sapphire, SiC, Si, MgAl ₂ O ₄ , LiTaO ₃ , ZrB ₂ , CrB ₂ , gallium nitride, and a composite in which a nitride semiconductor is grown on a substrate made of these compounds. Can be used. In view of the gist of the present invention, it is important that any of them is industrially easily available.

  Thereafter, the surface 1A of the base substrate 1 is cleaned, and an epitaxial growth mask is formed on the clean surface 1A. Here, inorganic particles 2 serving as an epitaxial growth mask (hereinafter sometimes simply referred to as a mask) are arranged on the surface 1A of the base substrate 1 ((B) in FIG. 1).

  In the method for manufacturing a semiconductor single crystal substrate according to the present invention, in the heteroepitaxial growth method on the base substrate 1, the area of the cross section parallel to the surface of the base substrate in the epitaxial growth crystal grown on the base substrate 1 is the surface of the base substrate 1. It is characterized by growing so as to change as will be described later depending on the distance from. Further, the present invention is characterized in that an epitaxial growth mask that enables this is used, and a mask manufacturing method for forming a mask having such a structure on a base substrate.

  The feature of this epitaxial growth mask is that the area of the cross section parallel to the surface of the underlying substrate of the epitaxial growth mask is a function of the distance from the surface of the underlying substrate.

  In the epitaxial growth mask using the inorganic particles 2, the contact area A with the base substrate 1 is smaller than the area B of the growth surface of the base substrate 1, and the cross-sectional area C on the plane parallel to the growth surface of the base substrate 1 is It has a structure in which it increases as it moves away from the substrate 1, reaches a maximum value D when it moves away by a predetermined distance, decreases as it moves away from the base substrate 1, and terminates.

  Here, the magnitude relationship between each area and the maximum value D is A <C <D <B. In addition, each of the above areas is defined by a projected area onto a plane perpendicular to the normal direction set up perpendicular to the surface of the base substrate 1. That is, even when the underlying substrate 1 has unevenness, B is not the surface area including the unevenness but the projected area in the normal direction with respect to the main surface of the underlying substrate 1. The same applies to the cross-sectional area of the epitaxial crystal layer described above. The epitaxial growth direction is defined as the direction normal to the main surface of the base substrate 1.

  Therefore, the semiconductor epitaxial substrate obtained by the method according to the present invention shown in FIG. 1 is defined by an area obtained by subtracting the mask cross-sectional area C from the area B of the substrate growth surface, and the cross-sectional area (B− C) has a profile in which (BA)> (BC)> (BD) changes along the epitaxial growth direction, and finally BC = B (ie, C = 0). It is characterized by having.

  Next, referring to FIGS. 2 and 3, the structure of the epitaxial growth mask will be described more specifically.

  2A is a plan view of the base substrate 1 on which the inorganic particles 2 are arranged, FIG. 2B is a sectional view taken along line XX, and FIG. 2C is a group 3-5 nitride semiconductor layer formed thereon. It is XX sectional drawing of the (A) in a state.

  FIG. 3 is a cross-sectional view of the substrate shown in FIG. 2C when it is crossed so as to be orthogonal to the normal direction to the surface 1A (main surface) of the base substrate 1, FIG. 3 is a sectional view taken along line 2-2, FIG. 3C is a sectional view taken along line 3-3, FIG. 3D is a sectional view taken along line 4-4, FIG. (E) is a sectional view taken along line 5-5.

  As can be seen by comparing (C) of FIG. 2 and each of FIGS. 3A and 3B, when attention is paid to the cross-sectional area of the inorganic particles 2 forming the epitaxial growth mask, the contact area between the base substrate 1 and the epitaxial growth mask 2 is as follows. It is smaller than the area of the growth surface of the substrate 1. Then, the cross-sectional area C of the inorganic particles 2 in a plane parallel to the growth surface of the base substrate 1 increases as the distance from the base substrate 1 increases, and reaches a maximum value at a position away from the base substrate 1 by a predetermined distance (position on the line 3-3). (See (B) and (C) of FIG. 3). If the position of the cross section along line 3-3 is exceeded, the structure is such that it decreases as it moves away from the base substrate 1 and terminates (see FIGS. 3D and 3E).

  Therefore, the area of the cross section parallel to the surface of the underlying substrate 1 of the semiconductor epitaxial substrate obtained by the method of the present invention is defined as the area obtained by subtracting the mask cross sectional area C from the area B of the substrate growth surface. The cross-sectional area (BC) of the layer changes along the epitaxial growth direction as (BA)> (BC)> (BD), and finally BC = B (ie, C = 0) ).

  The method for forming an epitaxial growth mask having the above-described structure can use a photolithography process generally used in semiconductor processing. The mask pattern may be any of various two-dimensional geometric periodic structures including a stripe-shaped structure known in publicly known literature on ELOG, but is not necessarily a periodic structure, and is an irregular island shape. It may be a structure. In the case of an irregular island structure, the mask can be formed using a simple film forming method such as a vapor deposition method without necessarily using a complicated lithography process. In general, the cross-sectional structure of such a mask is not defined in detail, and a flat mask is often formed in a normal lithography process or a film forming method such as a vapor deposition method.

  Since the epitaxial growth mask used in the method of the present invention has the above-described configuration, BC is the mask opening area. In order to form such a mask structure, for example, a mask having a large aperture ratio is once formed in a lithography process, and then a mask having a small aperture ratio is formed on top of it, or a mask having a large aperture ratio is further formed thereon. By further overlapping the layers, a mask having a desired cross-sectional area profile can be formed.

  A simpler method is a method of forming a mask by spraying or applying a granular material or a fibrous material made of a material as a mask material on a substrate, as shown in this embodiment.

  As the shape of the granular material or fibrous material that can be used at this time, the cross-sectional shape is preferably a circle or an ellipse. Moreover, even if it is a complicated regular structure or a complicated irregular structure, it should just be a form in which the envelope of the outermost surface can be described by a set of arcs, and various cross-sectional shapes such as broad beans, gourds, etc. A cross-sectional shape is included.

  In the present embodiment, by arranging the inorganic particles 2 on the surface 1A of the base substrate 1, an epitaxial growth mask that satisfies the above-described requirements is formed. As a result, the epitaxial crystal growth of the group 3-5 nitride semiconductor layer 3 formed on the base substrate 1 as described later is a cross section of the group 3-5 nitride semiconductor layer 3 parallel to the surface of the base substrate 1. Is gradually reduced in the process of growing from the surface of the base substrate 1 and then gradually enlarged, whereby the growth region is gradually increased during the growth of the group 3-5 nitride semiconductor layer 3. The epitaxial growth can be performed until at least the surface area of the group 3-5 nitride semiconductor layer 3 is equal to the surface area of the underlying substrate 1.

  The coverage of the epitaxial growth mask with respect to the base substrate 1 (mask coverage) is defined by the ratio of the maximum cross-sectional area D of the mask material to the area B of the surface of the substrate, and is not particularly limited, but is preferably 0.1% to 90%. %, More preferably 5% to 80%.

  If the coverage is 0.1% or more, a semiconductor light emitting device manufactured using the obtained substrate tends to exhibit higher luminance, and if it is 90% or less, the nitride semiconductor layer is epitaxially grown. There is a tendency that the growth start point at the start is sufficiently secured, and the nitride semiconductor layer is easily epitaxially grown. Further, a nitride semiconductor layer having a high affinity with the base substrate is easily embedded even if the coverage of the epitaxial growth mask with respect to the base substrate is high. For example, AlGaN can be embedded and grown with a higher mask coverage than GaN, and the higher the composition ratio of Al to Ga, the higher the tendency for embedded growth with respect to a higher mask coverage.

  Further, the arrangement of the inorganic particles 2 for forming the epitaxial growth mask may be random or regular, but the random one is said to be a dispersion or application of a granular material or a fibrous material. Since an epitaxial growth mask can be formed by a very simple process, manufacturing is easy, which is preferable.

  In the case of a semiconductor single crystal substrate used for manufacturing a semiconductor light emitting device, a high emission efficiency can be obtained when a granular material is used as an epitaxial growth mask as in the present embodiment, which is a more preferable form.

  The height of the epitaxial growth mask can be arbitrarily selected depending on the thickness of the epitaxial growth crystal to be formed on the underlying substrate 1, but is usually preferably about 50 μm or less, more preferably 10 μm in order to make it easier to embed the epitaxial growth mask in the epitaxial growth. It is as follows. When the epitaxial growth mask is formed by applying a granular material or a fibrous material on a base substrate, these materials are preferably applied in a monodispersed state. As described above, in the case of forming a substrate used for manufacturing a semiconductor light-emitting device, a high-efficiency efficiency is obtained when a granular material or a fibrous material is used. The cross-sectional diameter of the fibrous material is more preferably in the range of about 5 to 0.2 times the wavelength of light related to the light emitting device.

As a material for the epitaxial growth mask, it is necessary to use a material that can withstand the subsequent epitaxial crystal growth process, and it is necessary to be an inorganic substance having a melting point, a sublimation temperature, or a decomposition temperature higher than the epitaxial growth process temperature. Nitride semiconductor described in this _{embodiment, Al x In y Ga z N} ( However, 0 ≦ x, y, a z ≦ 1, and x + y + z = 1) formation of an epitaxial growth mask for the schematic 1,200 ° C. approximately Inorganic substances having the above heat resistance are preferred.

  Specific examples include generally known compounds such as oxides, nitrides, carbides, borides, and sulfides. More specifically, examples of the oxide include silica, alumina, zirconia, titania, ceria, zinc oxide, tin oxide, yttrium aluminum garnet (YAG), and the like, and these constituent elements are partially substituted with other elements. Is also included.

  Examples of the nitride include silicon nitride, aluminum nitride, boron nitride, and the like, and those in which these constituent elements are partially substituted with other elements are also included. For example, a compound such as sialon composed of silicon, aluminum, oxygen, and nitrogen can also be used.

  Examples of the carbide include SiC, boron carbide, diamond, graphite, fullerene, and the like, and those in which these constituent elements are partially substituted with other elements are also included.

Al _x In _y Ga _z N that is grown on underlying substrate 1 (where, 0 ≦ x, y, with z ≦ 1, x + y + z = 1) , the on the mask material or not grow, or a very slow growth rate The so-called selective growth property is required. Such selective growth is considered to be determined mainly by the affinity between the epitaxial growth layer and the material to be grown. Materials such as alumina listed above, have high affinity for the epitaxial growth layer, since the intact as a mask material is difficult to _{use, Al x In y Ga z N} ( However, 0 ≦ x, y, z ≦ 1 and low in affinity with x + y + z = 1), and can be used after being subjected to a surface treatment such as coating with a material such as silicon oxide, silicon nitride, tungsten nitride, titanium nitride, zirconium boride, or chromium boride. .

  As a method for arranging inorganic particles on the base substrate, which is adopted in the present embodiment as one of the most simple and effective methods for forming an epitaxial growth mask, for example, the following method can be cited. The inorganic particles are easily arranged on the base substrate by immersing the base substrate in a slurry in which the inorganic particles are dispersed in a medium such as water, or by applying the slurry to the base substrate and spraying it and then drying. be able to. A spinner can also be used during the drying process. The coverage of the base substrate with inorganic particles (the value obtained by subtracting the aperture ratio in the mask from 100%) can be arbitrarily controlled by adjusting the pretreatment of the base substrate, the slurry medium and particle concentration, and the coating conditions at this time. Can do.

  By disposing the inorganic particles 2 on the base substrate 1 as described above, a mask covering portion and a mask opening portion are formed as shown in FIG. That is, the inorganic particles 2 arranged on the base substrate 1 act as a mask during the growth of the group 3-5 nitride semiconductor layer in the next step, and the area without the inorganic particles 2 on the surface 1A of the base substrate 1 is the growth region 1B. It becomes.

  Next, a process of forming a group 3-5 nitride semiconductor layer 3 by depositing a group 3-5 nitride semiconductor on the base substrate 1 will be described.

  When a source gas or the like is supplied onto the base substrate 1 on which the inorganic particles 2 are arranged according to the epitaxial growth method of the group 3-5 nitride semiconductor, the group 3-5 nitride semiconductor grows from the growth region 1B, and the group 3-5 The nitride semiconductor layer 3 grows on the base substrate 1 so as to embed the arranged inorganic particles ((C) in FIG. 1).

  As described above, the epitaxial growth of the semiconductor is started from the surface of the base substrate exposed at the mask opening, and the epitaxial growth proceeds along the mask surface. Finally, the epitaxial layer completely embeds the mask, and the surface thereof. Is epitaxially grown until it becomes flat. Therefore, the epitaxial crystal growth of the group 3-5 nitride semiconductor layer 3 is performed once the area of the cross section parallel to the surface of the base substrate 1 of the group 3-5 nitride semiconductor layer 3 grows from the surface of the base substrate 1. The growth region is gradually reduced and then gradually enlarged, whereby the growth region is temporarily narrowed down during the growth of the group 3-5 nitride semiconductor layer 3, and the epitaxial growth is performed in the group 3-5 nitride. This is performed until the area of the surface of the semiconductor layer 3 is equal to the area of the surface of the base substrate 1.

  Even when the group 3-5 nitride semiconductor layer 3 is further grown and the inorganic particles 2 are embedded in the group 3-5 nitride semiconductor layer 3 by further epitaxial growth, the group 3-5 nitride semiconductor layer is 3 grow further. As a result, the group 3-5 nitride semiconductor layer 3 in which the inorganic particles 2 are embedded can be formed on the base substrate 1 ((D) of FIG. 1). As shown in FIGS. 1C and 1D, a group 3-5 nitride semiconductor is grown while forming a facet structure on the base substrate 1 on which the inorganic particles 2 are arranged, and then a facet structure is formed. When the group 3-5 nitride semiconductor layer 3 having a flattened surface is embedded, high quality crystallinity is obtained.

  Examples of the epitaxial growth method for forming the group 3-5 nitride semiconductor layer 3 used in the steps (C) and (D) of FIG. 1 include the MOVPE method, the MBE method, and the HVPE method.

Here, one of the most effective embodiment of the further invention, Al _x using MOVPE method In _y Ga _z N (However, 0 ≦ x, y, with z ≦ 1, x + y + z = 1) epitaxial growth of crystals In this embodiment, epitaxial growth is performed using an epitaxial growth mask formed by dispersing or coating silica particles in colloidal silica on a sapphire substrate.

  As for the material of the epitaxial growth mask, the uncovered region of the mask is made of a material having selective growth properties with respect to the mask, and when the mask is placed on the base substrate, the epitaxial growth mask is oriented in the epitaxial growth direction from the base substrate. Any shape having a necessary cross-sectional area profile may be used. Silica particles in colloidal silica (hereinafter sometimes referred to as colloidal silica particles) are less likely to cause secondary aggregation than general inorganic particles and are spherical silica particles having a uniform particle size. Since the cross-sectional area profile along the epitaxial growth direction can be controlled by the coverage and the average grain size, it is suitable for achieving the object of the present invention.

  Note that the mask material is not necessarily a simple material such as colloidal silica particles that can be applied and dispersed in a monodispersed state. Needless to say, the material of the present invention can be used for carrying out the method of the present invention as long as the material has a predetermined selective growth property and a reproducible cross-sectional area profile along the epitaxial growth direction from the underlying substrate.

  When the group 3-5 nitride semiconductor layer 3 is crystal-grown on the base substrate 1 using the MOVPE method, the following compounds can be used as starting materials.

Examples of Group 3 materials include general formulas such as trimethylgallium [(CH ₃ ) ₃ Ga, hereinafter sometimes referred to as TMG] and triethylgallium [(C ₂ H ₅ ) ₃ Ga, hereinafter sometimes referred to as TEG]. Trialkylgallium represented by R ₁ R ₂ R ₃ Ga (where R ₁ , R ₂ and R ₃ represent lower alkyl groups); trimethylaluminum [(CH ₃ ) ₃ Al, hereinafter referred to as TMA General formula R ₁ R ₂ R ₃ such as triethylaluminum [(C ₂ H ₅ ) ₃ Al, hereinafter sometimes referred to as TEA] and triisobutylaluminum [(i-C ₄ H ₉ ) ₃ Al]. Trialkylaluminum represented by Al (wherein R ₁ , R ₂ and R ₃ represent lower alkyl groups); trimethylamine alane [(CH ₃ ) ₃ N: AlH ₃ ]; trimethylindium [(CH ₃ ) _Three In, hereinafter sometimes referred to as TMI], general formula R ₁ R ₂ R ₃ In such as triethylindium [(C ₂ H ₅ ) ₃ In] (where R ₁ , R ₂ and R ₃ are lower alkyl In which trialkylindium represented by (1) or ( ₂ ) is substituted with one or two alkyl groups from trialkylindium such as diethylindium chloride [(C ₂ H ₅ ) ₂ InCl], indium chloride [InCl] And indium halides represented by the general formula InX (X is a halogen atom). These may be used alone or in combination.

  Examples of the Group 5 raw material include ammonia, hydrazine, methyl hydrazine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, t-butylamine, and ethylenediamine. These can be used alone or in any combination. Among these raw materials, ammonia and hydrazine are preferable because they do not contain carbon atoms in their molecules and thus cause less carbon contamination in the semiconductor.

  In the MOVPE method, gases such as nitrogen, hydrogen, argon, and helium can be used alone or as a mixture, and hydrogen, nitrogen, and helium are preferable as the growth atmosphere gas and the carrier gas for the organometallic raw material.

  The above source gases are introduced into the reaction furnace, and the group 3-5 nitride semiconductor layer 3 is grown on the growth region 1B of the base substrate 1. The reaction furnace includes a raw material supply line for supplying a raw material gas from the raw material supply apparatus to the reaction furnace, and a susceptor for heating the base substrate 1 is provided in the reaction furnace. The susceptor usually has a structure that can be rotated by a rotating device in order to uniformly grow the group 3-5 nitride semiconductor layer 3. A heating device such as an infrared lamp for heating the susceptor is provided inside the susceptor. By this heating, the source gas supplied to the reaction furnace through the source supply line is thermally decomposed on the base substrate 1 so that a desired compound can be vapor-phase grown on the base substrate 1.

On the ground substrate 1 heated in advance to a predetermined temperature during crystal _{growth, Al x In y Ga z N} ( However, 0 ≦ x, y, with z ≦ 1, x + y + z = 1) represented by the epitaxial crystal The source gas corresponding to the desired composition and added impurities are sequentially sent in, and the epitaxial growth of the group 3-5 nitride semiconductor is caused on the surface of the base substrate 1 by the thermal decomposition reaction. It is also possible to obtain an epitaxial substrate having a desired structure by performing crystal growth while appropriately switching the source gas, temperature, carrier gas and the like according to the design of the epitaxial layer structure. Of the raw material gas supplied to the reaction furnace, unreacted raw material gas is discharged from the exhaust line to the outside of the reaction furnace and sent to the exhaust gas treatment device.

Al _x In _y Ga _z N (where 0 ≦ x, y, with z ≦ 1, x + y + z = 1 and is) the case of system crystal, usually, first, relatively low temperature Al _x In _y Ga _z N (where After forming an amorphous or polycrystalline thin buffer layer (0 ≦ x, y, z ≦ 1 and x + y + z = 1), desired epitaxial growth is performed at around 900 ° C. to 1,300 ° C. In this case, the crystal layer is GaN, AlGaN, InGaN and various crystal, or more generally Al _x In _y Ga _z N (However, 0 ≦ x, y, with z ≦ 1, x + y + z = 1) crystal layer which is represented by Alternatively, multi-layer growth with different compositions and film thicknesses can be performed, but here, the case of performing the most general GaN crystal growth has been described.

  Since GaN does not normally grow on silicon oxide, crystal growth starts from the gap between the inorganic particles 2 such as colloidal silica particles coated on the underlying substrate 1, that is, the opening of the epitaxial growth mask. Further, the GaN film thickness when grown on a flat base substrate 1 without forming such a mask, that is, without applying the inorganic particles 2, is sufficiently thicker than the mask thickness, that is, the diameter of the inorganic particles 2 here. By performing the epitaxial growth under the same crystal growth conditions and time as the time, an epitaxial crystal having a flat surface completely embedded with the mask, that is, the inorganic particles 2 can be obtained (see FIG. 1D).

  The half width of the reflection peak due to (004) and (302) plane reflection obtained by measuring the epitaxially grown GaN crystal grown at this time by X-ray diffraction is epitaxially grown under the same conditions without using a colloidal silica mask. Compared to the half-value width in the case of GaN, a small value was obtained, and it was confirmed that the obtained crystal was better when a mask made of colloidal silica was used.

  In the embodiment described above, the sapphire substrate 11 is used as the base substrate, the colloidal silica particles 12 are arranged on the sapphire substrate 11 to form an epitaxial growth mask, and a group 3-5 nitride semiconductor is grown thereby. The cross section of the obtained epitaxially grown GaN crystal 13 was closely observed with a transmission electron microscope (TEM), and the following facts were obtained.

  That is, it is recognized that the colloidal silica particles applied on the sapphire substrate are embedded in the GaN epitaxial crystal as it is. The colloidal silica particles have a substantially spherical shape, and are placed on the sapphire substrate through substantially point-like contact points. However, the GaN crystal does not reach the lower part of the colloidal silica particles. However, it grows from almost the entire surface of the sapphire substrate except for the point-like contact portion between the colloidal silica particles and the sapphire substrate.

  In addition, the surface of the colloidal silica particles is covered with GaN with almost no gap, and there is a slight gap at the top of the colloidal silica particles, but the gap disappears in the part where the GaN epitaxial growth has progressed, A flat crystal face without a gap is formed on the outermost surface portion.

  FIG. 4 schematically shows the state of the TEM image observed at this time. In the vicinity of the interface with the sapphire substrate 11, many dislocations considered to be caused by lattice mismatch between GaN and sapphire are recognized, but most of these dislocations are terminated when they reach the lower half interface of the colloidal silica particles 12. (Dislocation 14 in FIG. 4). In addition, although a good crystal having almost no dislocation grows above the upper half interface on the surface side of the colloidal silica particle 12, a gap or a single large dislocation is observed at the top of the colloidal silica particle 12 (FIG. 4 rearrangement 16).

  Further, in a region outside the projected area of the colloidal silica particles 12, dislocations generated from the vicinity of the surface of the sapphire substrate 11 are not epitaxially grown because there are no dislocation block bodies like the colloidal silica particles 12 while repeating coherence with the crystal growth. Interestingly, the dislocations 15 in FIG. 4 are interestingly horizontal in the gaps between the colloidal silica particles 12 and at a level similar to or even higher than the top of the colloidal silica particles 12. A space extending from the top of the colloidal silica particle 13 by bending and extending in the horizontal direction or a portion terminated by a dislocation is observed (dislocation 17 in FIG. 4). As a result, the dislocation density at the outermost surface portion of the epitaxial crystal is greatly reduced as compared with the case where a mask made of colloidal silica particles is not used. The mechanism of the dislocation reduction effect is unknown in detail because the vertical and horizontal directions are unclear.

  Apart from the ELOG mechanism, bulk crystal growth from a normal melt can also be recalled. In bulk crystal growth typified by the Czochralski method, a necking process is often used in which a seed crystal is immersed in a melt to start crystal growth and then the crystal diameter is once narrowed. After the necking step, the crystal diameter is gradually increased and finally the cylindrical single crystal having the desired diameter is pulled up, and dislocations generated at the initial stage of crystal growth due to the introduction of the necking step are terminated by coalescence or release to the surface and reduced. Dislocation crystals are realized. In the case of the present invention, the crystal cross-sectional profile can be considered to be similar to such a necking process. That is, if seed crystal growth starts from the sapphire surface, the cross-sectional area of the epitaxial layer parallel to the substrate surface is minimized to become a necking portion where it corresponds to the maximum diameter of colloidal silica after the progress of growth, and then gradually expands. Thus, the desired diameter (here, equivalent to the cross-sectional area of the epitaxial crystal layer having the same area as the area of the substrate surface) is reached.

  In any case, although the detailed mechanism is unknown, the present inventors have further intensively studied and found that when the mask shape has a cross-sectional area profile represented by colloidal silica particles, a good epitaxial crystal can be obtained. It is. That is, the mask cross-sectional area is such that the contact area A with the substrate is smaller than the area B of the growth surface of the substrate and the cross-sectional area C in the plane parallel to the growth surface of the substrate is D at the maximum distance D. Thereafter, as the distance from the substrate increases, the cross-sectional area C decreases and terminates, and the mask material has characteristics that enable selective growth with respect to the target semiconductor material, similar to silica. The cross-sectional area (BC) of the epitaxial layer defined by the area obtained by subtracting the mask cross-sectional area C from the area B of the substrate growth surface is (BA)> (BC) along the epitaxial growth direction. )> (BD), and finally epitaxial growth having a profile of BC = B (that is, C = 0) is possible, and an epitaxial substrate having excellent crystallinity is provided. Can

  In the above description, the spherical mask using method, which is the most realistic epitaxial growth mask forming method for manufacturing such an epitaxial crystal, has been described. However, the cross-sectional area of the epitaxial layer can also be obtained by other means such as forming an appropriate concavo-convex process on the underlying substrate, or forming an appropriate void in the epitaxially grown crystal by controlling the mask structure and the epitaxial crystal growth mode. A similar effect can be expected if a profile that is initially wide, then narrow, and last is widened.

  Therefore, the epitaxial crystal growth of the group 3-5 nitride semiconductor layer 3 formed on the base substrate 1 is such that the area of the cross section parallel to the surface of the base substrate 1 of the group 3-5 nitride semiconductor layer 3 is the base substrate 1. In the process of growing from the surface, the structure may be such that it is once reduced and then enlarged so that the growth region is once narrowed during the growth of the group 3-5 nitride semiconductor layer 3. The epitaxial crystal growth of the group 3-5 nitride semiconductor layer 3 is not necessarily performed once the area of the cross section parallel to the surface of the base substrate 1 of the group 3-5 nitride semiconductor layer 3 grows from the surface of the base substrate 1. It is not necessary to gradually reduce the growth region during the growth of the group 3-5 nitride semiconductor layer 3 by gradually reducing and then gradually expanding.

  On the GaN single crystal epitaxial substrate manufactured in this way, having a low dislocation density and good crystal characteristics, continuously or once taken out of the furnace, the substrate is placed in the furnace again, and further desired. One or a plurality of epitaxial crystal layers necessary for various semiconductor devices according to the purpose can be grown.

A nitride semiconductor layer (a multilayer film necessary for the operation of the nitride semiconductor light-emitting element) used in such a semiconductor device, for example, a light-emitting diode, includes an n-type conductive layer and a p-type conductive layer. And a nitride semiconductor layer having a light-emitting layer sandwiched between them is preferable. In any layer, In _x Ga _y Al _z N (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ A layer made of a nitride semiconductor represented by z ≦ 1, x + y + z = 1) can be grown.

The nitride semiconductor layer made of a nitride semiconductor represented by In _x Ga _y Al _z N includes an n-type conductive layer, a p-type conductive layer, and a light emitting layer sandwiched therebetween. In addition, a single layer or multiple layers (including a case of a thick film layer or a superlattice thin film layer) necessary for making these layers into high-quality crystals may be included, and a buffer layer may be included. (A layer for growing the clad layer as a single crystal layer between the substrate and the clad layer) may be included. The n-type conductive layer may be composed of a plurality of layers such as an n-type contact layer and an n-type cladding layer. Similarly, the p-type conductive layer is also a plurality of layers such as a p-type contact layer and a p-type cladding layer. May consist of:

  As a more preferable configuration of the nitride semiconductor layer, a buffer layer made of GaN, AlN or the like, an n-type conductive layer (clad layer) made of n-GaN, n-AlGaN, or the like, InGaN, GaN, or the like. A light-emitting layer, a p-type conductive layer (cladding layer) made of undoped GaN, p-GaN, etc., a Mg-doped AlGaN, a cap layer made of Mg-doped GaN are sequentially laminated (for example, JP-A-6-260682, JP-A-7-15041, JP-A-9-64419, JP-A-9-36430).

  In the nitride semiconductor light emitting device of the present invention, the layer containing the epitaxial growth mask material formed using inorganic particles or the like may be any of the above layers, but the nitride semiconductor layer between the light emitting layer and the base substrate In the case where it is contained, an interface between the base substrate and the nitride semiconductor layer is preferable. In addition, when the epitaxial growth mask layer is completely included in the nitride semiconductor layer, it is also possible to use an epitaxial growth mask formed on an epitaxial GaN crystal layer previously grown on a sapphire substrate or the like once taken out of the growth furnace. it can.

  Furthermore, if the nitride semiconductor multilayer substrate of the present invention is processed and an electrode for supplying a current to the light emitting layer is provided, a nitride semiconductor light emitting device constituting the present invention is obtained. As an electrode constituting the nitride semiconductor light emitting device of the present invention, a commonly used electrode made of a metal such as Au, Pt, Pd or the like can be used.

  As described above, the epitaxial substrate grown using the epitaxial growth mask formed of the colloidal silica particles described in detail above naturally includes the epitaxial growth mask layer of the colloidal silica particles inside the crystal layer including the substrate. When using an epitaxial substrate as a device, it is common to form the device by processing the upper part of the epitaxial layer while leaving the substrate as it is. However, the substrate or the substrate and the lower part of the epitaxial layer may be removed or processed. In the present invention, a light emitting diode having excellent light emission characteristics can be obtained by forming a diode including an epitaxial growth mask made of colloidal silica used for epitaxial crystals.

  As mentioned above, although embodiment of this invention was described, these embodiment is an illustration to the last, Comprising: The scope of the present invention is not limited to these embodiment. The scope of the present invention is defined by the terms of the claims, and further includes meanings equivalent to the description of the claims and all modifications within the scope.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to the Example described below.

Example 1
As the base substrate, a sapphire substrate obtained by mirror polishing the C surface of sapphire was used. Colloidal silica particles contained in colloidal silica (manufactured by Fuso Chemical Industry Co., Ltd., PL-20 (trade name), primary particle size 370 nm, particle concentration 24% by weight) are used as inorganic particles that serve as an epitaxial growth mask. It was.

  A sapphire substrate was set on a spinner, and colloidal silica diluted to 10% by weight was applied thereon, followed by spin drying. When observed by SEM, the coverage of the growth substrate surface by colloidal silica particles was about 40%.

  Thus, after forming the epitaxial growth mask by colloidal silica particles on a sapphire substrate, the nitride semiconductor layer was epitaxially grown on the sapphire substrate, and the colloidal silica particles were embedded in the nitride semiconductor layer.

  The atmospheric pressure MOVPE method was used for the epitaxial growth. A GaN buffer layer having a thickness of about 500 mm was grown at 1 atm by supplying susceptor temperature of 485 ° C., carrier gas as hydrogen, and supplying carrier gas, ammonia and TMG. Next, after the temperature of the susceptor was set to 900 ° C., carrier gas, ammonia, and TMG were supplied to form an undoped GaN layer. Next, the furnace pressure was lowered to ¼ atm with a susceptor temperature of 1040 ° C., and carrier gas, ammonia and TMG were supplied to form an undoped GaN layer having a thickness of about 5 μm. As described above, a nitride semiconductor intermediate substrate in which colloidal silica particles are contained in layers in the GaN crystal was obtained.

  Observation of the obtained nitride semiconductor intermediate substrate with a cross-sectional transmission electron microscope (TEM) shows that the colloidal silica particles are embedded with GaN epitaxial crystals without any gaps, and the outermost surface of the epitaxial crystal layer is a flat surface parallel to the substrate surface. It was confirmed that

  That is, from the state where the epitaxial crystal cross-sectional area parallel to the surface of the substrate is equal to the area of the substrate surface excluding the portion where the colloidal silica particles are in contact with the substrate in the form of dots at positions close to the surface of the substrate. Once the epitaxial growth is completed, it is reduced in the direction in which the epitaxial growth proceeds and is minimized near the plane crossing the center of the colloidal silica particles aligned on the substrate to form a necking portion, which is then expanded. It was confirmed that the surface area of the epitaxial crystal was expanded until it became equal to the surface area of the substrate used for the epitaxial growth.

  Further, when the X-ray half width of this intermediate substrate was measured, a good value was obtained, with a half width of (004) reflection being 178 seconds and a half width of (302) reflection being 364 seconds.

  Subsequently, an n-type semiconductor layer, an InGaN light-emitting layer (MQW structure), and a p-type semiconductor layer are sequentially formed to form a blue LED nitride semiconductor multilayer substrate with an emission wavelength of 440 nm, and to expose the n-type contact layer. Etching, electrode formation, and element isolation were performed to obtain a nitride semiconductor light emitting element made of a nitride semiconductor. A semi-transparent electrode containing AuNi as a component was formed as the p-type electrode layer, and light from the InGaN emitting layer was extracted from the p-type electrode side.

  Next, this nitride semiconductor light emitting device is cut out as a chip having a side of about 300 μm, the sapphire substrate side is bonded onto a sintered aluminum nitride ceramic submount, and wire bonding is performed from the p-type electrode and the n-type electrode on the top of the chip. The electrode wire was pulled out and connected to an external terminal. The light output of the blue LED thus obtained at a current of 20 mA was measured and found to be 9.8 mW.

Example 2
Colloidal contained in colloidal silica (manufactured by Nippon Shokubai Co., Ltd., Seahoster KE-W50 (trade name), primary particle size 550 nm) (particle concentration 20% by weight diluted to 10% by weight) as inorganic particles Except that the silica particles were used, the inorganic particles were placed on the sapphire substrate in the same manner as in Example 1 to form an epitaxial growth mask. When observed by SEM, the coverage of the sapphire substrate surface with colloidal silica particles was about 36%. A group 3-5 nitride semiconductor was epitaxially grown in the same manner as in Example 1 on the sapphire substrate on which the colloidal silica particles were thus arranged. When observed by TEM, it was confirmed that the colloidal silica particles were embedded with GaN epitaxial crystals without gaps, and that the outermost surface of the epitaxial crystal layer was a flat surface parallel to the substrate surface.

  That is, the state in which the cross-sectional area of the epitaxial crystal parallel to the surface of the sapphire substrate is equal to the area of the surface of the sapphire substrate excluding the portion where the colloidal silica particles are in contact with the sapphire substrate in a point-like manner at a position close to the surface of the sapphire substrate From this, it is once reduced in the direction in which the epitaxial growth proceeds, and the necking portion is formed by being minimized near the plane crossing the center of the colloidal silica particles arranged on the sapphire substrate, and then enlarged to complete the epitaxial growth. It was confirmed that the area of the surface of the epitaxial crystal at the time was expanded until it became equal to the area of the surface of the sapphire substrate used for the epitaxial growth.

  Further, when the X-ray half width of the intermediate substrate thus obtained was measured, (004) the half width of the reflection was 192 seconds and (302) the half width of the reflection was 380 seconds. It was found that an excellent intermediate substrate was obtained.

  Using the nitride semiconductor substrate thus obtained, a nitride semiconductor light emitting device was produced in the same manner as in Example 1. It was 17.0 mW when the optical output of the obtained blue LED at an electric current of 20 mA was measured.

Example 3
An epitaxial growth mask made of colloidal silica particles was formed in the same manner as in Example 1 except that a GaN layer grown on a sapphire substrate having a mirror-polished C surface of sapphire was used. When observed by SEM, the coverage of the growth substrate surface by colloidal silica particles was about 32%. The subsequent growth of the nitride semiconductor layer, the production of the nitride semiconductor multilayer substrate, and the production of the nitride semiconductor light emitting device were carried out in the same manner as in Example 1. At this time, when the X-ray half width of the intermediate substrate was measured, the (004) reflection half width was 163 seconds and the (302) reflection half width was 392 seconds. When the light output of the obtained blue LED at an electric current of 20 mA was measured, it was 12.5 mW.

Example 4
The substrate is the same as in Example 1 except that a substrate obtained by growing an AlGaN layer on a mirror-polished C-plane of sapphire is used, and the coverage of the growth substrate surface by colloidal silica particles is about 70%. The growth of the nitride semiconductor layer, the production of the nitride semiconductor multilayer substrate, and the production of the nitride semiconductor light emitting device were carried out in the same manner as in Example 1. Further, when the X-ray half width of the intermediate substrate at this time was measured, a good value was obtained, with the half width of (004) reflection being 188 seconds and the half width of (302) reflection being 373 seconds. Further, when the light output of the finally obtained blue LED at an electric current of 20 mA was measured, it was 10.5 mW.

Comparative Example 1
A GaN nitride semiconductor intermediate substrate having a thickness of about 5 μm was obtained in the same manner as in Example 1 except that inorganic particles were not used, that is, an epitaxial growth mask made of inorganic particles was not formed on the sapphire substrate. It was. The X-ray diffraction half width was measured and found to be 268 seconds for (004) reflection and 566 seconds for (302) reflection. Subsequently, a nitride semiconductor multilayer substrate was formed on the intermediate substrate in the same manner as in Example 1, and a light emitting device was manufactured using the nitride semiconductor multilayer substrate. When the light output of the obtained blue LED at an electric current of 20 mA was measured, it was 3.0 mW.

Comparative Example 2
As a selective growth mask, a stripe-shaped silicon oxide mask having a mask width of 5 μm, an aperture ratio of 50% and a thickness of 500 nm was formed on a sapphire substrate, and ELOG growth was performed. When an intermediate substrate having a thickness of about 5 μm was obtained and its X-ray diffraction half width was measured, it was 272 seconds for (004) reflection and 387 seconds for (302) reflection. Subsequently, a nitride semiconductor multilayer substrate was formed on the intermediate substrate in the same manner as in Example 1 and Comparative Example 1, and a light-emitting device was manufactured using this. When the light output of the obtained blue LED at a current of 20 mA was measured, it was 4.0 mW.

Process drawing for describing one embodiment of the present invention. 4A and 4B illustrate an example of a structure of a mask used in the present invention. FIG. 3C is a cross-sectional view of FIG. 2C for explaining the profile of the cross-sectional area of the mask shown in FIG. The schematic diagram for demonstrating the observation result of the state of a dislocation in one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base substrate 1B Growth area | region 2 Inorganic particle 3 3-5 group nitride semiconductor layer 11 Sapphire substrate 12, 13 Colloidal silica particle 14, 15, 16, 17 Dislocation

Claims (5)

In a method of manufacturing a semiconductor single crystal substrate by epitaxially growing a semiconductor crystal on a sapphire substrate,
A mask material having an opening is placed on the sapphire substrate, epitaxial growth of the semiconductor crystal is started from the inside of the opening toward the outside, and the semiconductor crystal is epitaxially grown on the sapphire substrate along the shape of the mask material. By doing
The semiconductor crystal is epitaxially grown so that an area of a cross section parallel to the surface of the sapphire substrate of the semiconductor crystal is gradually reduced and then gradually enlarged in the process of growing from the surface of the sapphire substrate. Thus, the growth region is temporarily narrowed down during the growth of the semiconductor crystal, and the epitaxial growth is performed until at least the surface area of the semiconductor crystal is equal to the surface area of the sapphire substrate used for the epitaxial growth. ,
As the mask material, silica particles contained in colloidal silica of an aqueous dispersion are used.
A method for manufacturing a semiconductor single crystal substrate.   The method for producing a semiconductor single crystal substrate according to claim 1, wherein a cross section of the mask material parallel to the surface of the sapphire base substrate is circular.   The method of manufacturing a semiconductor single crystal substrate according to claim 1, wherein the mask material is spherical.   2. The method for producing a semiconductor single crystal substrate according to claim 1, wherein the epitaxial crystal grown on the sapphire substrate is a sublimable or decomposable substance having no melting point at atmospheric pressure and belonging to a Group 3-5 compound semiconductor.   The method for producing a semiconductor single crystal substrate according to any one of claims 1 to 4, wherein the epitaxial crystal is a group 3-5 nitride semiconductor.

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