JP2013030617A - Composite substrate and manufacturing method therefor, and composite wafer - Google Patents

Abstract

Kind Code: A1 A group III nitride is formed on a composite substrate in which a different composition substrate and a group III nitride layer different in chemical composition and a group III nitride layer are bonded together without causing warpage and cracks. A composite substrate capable of forming a physical epitaxial layer and a method for manufacturing the same are provided.
The composite substrate 2D includes a different composition substrate 10 having a chemical composition other than the group III nitride, a group III nitride layer 21 bonded to the different composition substrate 10, and a group III nitride layer 21. Are separated into a plurality of group III nitride tiles 21p having at least one type of planar shape that can be planarly filled.
[Selection] Figure 1

Description

  The present invention relates to a composite substrate suitable for forming a group III nitride epitaxial layer, a manufacturing method thereof, and a composite wafer including such a composite substrate and a group III nitride epitaxial layer.

  As a substrate for manufacturing a GaN-based semiconductor device having good characteristics at low cost by epitaxially growing a GaN-based semiconductor layer having good crystallinity on the substrate, for example, JP 2008-10766 A (Patent Document 1) is expensive. Instead of a GaN free-standing substrate, a substrate is proposed in which a GaN thin film is bonded to a heterogeneous substrate having a chemical composition other than GaN.

JP 2008-10766 A

  However, in the bonded substrate described in Japanese Patent Application Laid-Open No. 2008-10766 (Patent Document 1), a different composition substrate (for example, sapphire substrate) having a chemical composition different from that of GaN is used. When a GaN-based semiconductor layer is grown on a GaN thin film, the GaN-based semiconductor layer grown on the bonded substrate is warped or cracked due to the difference in thermal expansion coefficient between the different composition substrate and the GaN thin film and the GaN-based semiconductor layer. Therefore, there is a problem that the yield of the obtained GaN-based semiconductor device is reduced.

  The present invention is applicable to a composite substrate in which a different composition substrate having a chemical composition different from that of a group III nitride and a group III nitride layer are bonded to each other on the composite substrate without causing warpage and cracks. It is an object of the present invention to provide a composite substrate capable of forming a nitride epitaxial layer, a manufacturing method thereof, and a composite wafer including such a composite substrate and a group III nitride epitaxial layer.

  The present invention includes a different composition substrate having a chemical composition other than the group III nitride, and a group III nitride layer bonded to the different composition substrate, and the group III nitride layer is at least one type capable of plane filling The composite substrate is separated into a plurality of group III nitride tiles having a planar shape.

In the composite substrate according to the present invention, the planar shape of the group III nitride tile can be at least one selected from the group consisting of a striped shape, a triangular shape, a quadrangular shape, and a hexagonal shape. In addition, the length of the longest side of the group III nitride tile can be 2000 μm or less. Further, the dislocation density of the group III nitride tile can be 1 × 10 ⁷ cm ⁻² or less.

  Moreover, this invention is a composite wafer containing said composite substrate and the group III nitride epitaxial layer formed on the group III nitride layer of a composite substrate.

  Further, the present invention is a method for manufacturing the above-described composite substrate, the step of forming an ion implantation region on one main surface side of the group III nitride substrate, and a plane on one main surface side of the different composition substrate A step of forming a plurality of convex portions having at least one type of planar shape that can be filled, a main surface on the side where the ion implantation region of the group III nitride substrate is formed, and a convex portion of the different composition substrate are formed. And a step of separating the group III nitride substrate into a group III nitride layer bonded to the different composition substrate and the remaining group III nitride substrate in the ion implantation region. A method for manufacturing a substrate.

  The present invention also provides a method for manufacturing the composite substrate, wherein a step of forming an ion implantation region on one main surface side of the group III nitride substrate, and an ion implantation region of the group III nitride substrate are formed. Forming a plurality of convex portions having at least one type of planar shape capable of plane filling and a convex portion on the side where the ion implantation region of the group III nitride substrate is formed on the main surface side. A step of bonding the main surface and one main surface of the different composition substrate; a group III nitride substrate in the ion implantation region; a group III nitride layer bonded to the different composition substrate; and the remaining group III nitride substrate And a step of separating the substrate into a composite substrate.

  According to the present invention, even a composite substrate in which a different composition substrate having a chemical composition different from that of Group III nitride and a Group III nitride layer are bonded to each other on the composite substrate without causing warpage and cracks. It is possible to provide a composite substrate capable of forming a group III nitride epitaxial layer and a manufacturing method thereof, and a composite wafer including such a composite substrate and a group III nitride epitaxial layer.

It is a schematic sectional drawing which shows an example of the composite substrate concerning this invention. It is a schematic sectional drawing which shows an example of the composite wafer concerning this invention. It is the schematic which shows an example of the planar arrangement | positioning of the group III nitride tile in the composite substrate concerning this invention. It is the schematic which shows another example of the planar arrangement | positioning of the group III nitride tile in the composite substrate concerning this invention. It is the schematic which shows another example of the planar arrangement | positioning of the group III nitride tile in the composite substrate concerning this invention. It is the schematic which shows another example of the planar arrangement | positioning of the group III nitride tile in the composite substrate concerning this invention. It is the schematic which shows another example of the planar arrangement | positioning of the group III nitride tile in the composite substrate concerning this invention. It is the schematic which shows another example of the planar arrangement | positioning of the group III nitride tile in the composite substrate concerning this invention. It is the schematic which shows another example of the planar arrangement | positioning of the group III nitride tile in the composite substrate concerning this invention. It is the schematic which shows another example of the planar arrangement | positioning of the group III nitride tile in the composite substrate concerning this invention. It is a schematic sectional drawing which shows an example of the manufacturing method of the composite substrate concerning this invention. It is a schematic sectional drawing which shows another example of the manufacturing method of the composite substrate concerning this invention. It is a schematic sectional drawing which shows another example of the manufacturing method of the composite substrate concerning this invention.

[Composite substrate]
{Embodiment 1}
1 to 10, one embodiment of a composite substrate according to the present invention includes a different composition substrate 10 having a chemical composition other than a group III nitride, and a group III nitride layer bonded to the different composition substrate 10. 21 and the group III nitride layer 21 is separated into a plurality of group III nitride tiles 21p, 21q, and 21r having at least one type of planar shape capable of plane filling. In the composite substrate 2D of the present embodiment, the group III nitride layer 21 is separated into a plurality of group III nitride tiles 21p, 21q, and 21r. Therefore, on the plurality of group III nitride tiles 21p, 21q, and 21r, A group III nitride epitaxial layer having high crystallinity can be grown without causing warpage and cracks.

(Different composition substrate)
The different composition substrate 10 of the composite substrate 2D of the present embodiment is a substrate having a chemical composition other than the group III nitride, and examples thereof include a sapphire substrate, a SiC substrate, and a Si substrate.

(Group III nitride layer)
The group III nitride layer 21 of the composite substrate 2D of the present embodiment is a layer formed of group III nitride, for example, an Al _x In _y Ga _1-xy N layer (0 ≦ x, 0 ≦ y, x + y ≦ 1). Further, the group III nitride layer 21 is separated into a plurality of group III nitride tiles 21p, 21q, and 21r having at least one type of planar shape that can be planarly filled.

(Group III nitride tile)
The group III nitride tiles 21p, 21q, and 21r of the composite substrate 2D of the present embodiment have at least one type of planar shape that can be planarly filled. Here, plane filling refers to an operation of filling a plane with finite types of plane figures (tiles).

  The planar shape of the group III nitride tiles 21p, 21q, and 21r of the composite substrate 2D of the present embodiment is preferably at least one selected from the group consisting of a stripe shape, a triangular shape, a quadrangular shape, and a hexagonal shape. Details will be described below.

  Examples of the planar shape that can be filled with one type include an arbitrary triangle, an arbitrary parallelogram, an arbitrary parallel hexagon, an arbitrary quadrangle, and an arbitrary stripe shape. Here, from the viewpoint of high symmetry, the planar shape is a regular triangle (FIG. 3), a regular hexagon (FIG. 4), a rhombus (FIGS. 6 to 8), a regular square (FIG. 9), a parallel straight stripe (FIG. 10) and the like are preferable. In addition, this planar shape focuses on the fact that the group III nitride tile and the group III nitride epitaxial layer grown thereon have a hexagonal wurtzite crystal structure, and suppresses their warpage and cracks. However, from the viewpoint of securing a large plane area, a shape that can be plane-filled in six-fold rotational symmetry, for example, a regular triangle (FIG. 3), a regular hexagon (FIG. 4), a rhombus (FIG. 8), and the like are preferable. Further, such a planar shape is an equilateral triangle from the viewpoint that scribe lines can be formed in a straight line when a group III nitride epitaxial layer grown on a plurality of group III nitride tiles of a composite substrate is made into chips. , Diamonds (FIG. 6), regular squares (FIG. 9), parallel straight stripes (FIG. 10) and the like are preferable.

  In addition, the arrangement of the plurality of group III nitride tiles having such a planar shape is such that the group III nitride tile and the group III nitride epitaxial layer grown thereon have a hexagonal wurtzite crystal structure. From the viewpoint of securing a large plane area while focusing on the points and suppressing warping and cracking, a plurality of group III nitride tiles having a planar shape such as a regular triangle, a regular hexagon, and a rhombus are plane-filled in a six-fold rotational symmetry Are preferably arranged as shown (FIGS. 3, 4 and 8). In order to increase the crystallinity of the group III nitride tile and the group III nitride epitaxial layer grown thereon, the preferred order of the planar arrangement of a plurality of group III nitride tiles whose rhombic shape is shown in FIGS. Are in the order of high rotational symmetry, that is, the six-fold rotationally symmetric arrangement shown in FIG. 8, the two-fold rotationally symmetric arrangement shown in FIG. 7, and the one-time rotationally symmetric arrangement shown in FIG.

  Examples of the planar shape that can be filled with two or more types include regular triangles and regular tetragons, regular triangles and regular hexagons (FIG. 5), and the like. Such a planar shape focuses on the fact that both the group III nitride tile and the group III nitride epitaxial layer grown thereon have a hexagonal wurtzite crystal structure, while suppressing their warpage and cracks. From the viewpoint of securing a large plane area, shapes that can be plane-filled with six-fold rotational symmetry, such as regular triangles and regular hexagons (FIG. 5), are preferable. In addition, such a shape is, for example, a regular triangle and a regular hexagon (from the viewpoint of forming a scribe line with a straight line when separating a group III nitride epitaxial layer grown on a plurality of group III nitride tiles of a composite substrate. FIG. 5) is preferable.

  In addition, the arrangement of the plurality of group III nitride tiles having such a planar shape is such that the group III nitride tile and the group III nitride epitaxial layer grown thereon have a hexagonal wurtzite crystal structure. From the viewpoint of securing a large planar area while focusing on the points and suppressing warping and cracking, a plurality of group III nitride tiles having a planar shape such as a regular triangle, a regular hexagon, and a rhombus are plane-filled in a six-fold rotational symmetry It is preferable to arrange as shown in FIG.

  With reference to FIGS. 3 to 10, the plurality of group III nitride tiles 21p, 21q, and 21r in the composite substrate 2D of the present embodiment are formed with the group III nitride epitaxial layer without causing warpage and cracks on them. From the viewpoint of growth, the length S of the longest side of the group III nitride tiles 21p, 21q, 21r is preferably 2000 μm or less, and more preferably 800 μm or less.

  1 and 3 to 10, the distance D between the plurality of group III nitride tiles 21p, 21q, 21r separated from each other in the composite substrate 2D of the present embodiment is not particularly limited. From the viewpoint of growing the group III nitride epitaxial layer without causing warpage and cracks on the substrate, the product of the difference between the coefficient of thermal expansion between the group III nitride layer and the underlying substrate and the length of the longest side is 100 A distance of double or more is preferable, and a distance of 500 to 2000 is more preferable. The group III nitride epitaxial layer grown on the plurality of group III nitride tiles 21p, 21q, 21r is not particularly limited, but from the viewpoint of preventing warping and cracks, It is preferable that they are separated.

Further, the plurality of group III nitride tiles 21p, 21q, and 21r in the composite substrate 2D of the present embodiment has a group III nitride epitaxial layer with a low dislocation density and good crystallinity on them. The dislocation density of the nitride tiles 21p, 21q, and 21r is preferably 1 × 10 ⁷ cm ⁻² or less, and more preferably 5 × 10 ⁶ cm ⁻² or less. Here, the dislocation density of the group III nitride tiles 21p, 21q, 21r is the count of the number of etch pits per unit area formed by etching with KOH, and the darkness per unit area observed by CL (cathode luminescence). It is measured by counting the number of points.

  In the composite substrate 2D of the present embodiment, in order to increase the bonding strength between the different composition substrate 10 and the group III nitride layer 21 including the group III nitride tiles 21p, 21q, and 21r separated from each other, It is preferable that the bonding film 30 is interposed between the two.

(Bonding layer)
In the composite substrate 2D of the present embodiment, the bonding film 30 preferably used is not particularly limited, but from the viewpoint of increasing the bonding strength between the different composition substrate 10 and the group III nitride layer 21, a SiO ₂ film and a ZnO film TiO ₂ film, Ga ₂ O ₃ film, SnO ₂ film, In ₂ O ₃ film, Sb ₂ O ₃ film, Sb ₂ O ₅ film, TiN film and the like are preferable.

[Production method of composite substrate]
The method for manufacturing the composite substrate according to the present invention is not particularly limited as long as it is a method suitable for manufacturing the composite substrate 2D of the first embodiment, but from the viewpoint of efficiently manufacturing the composite substrate 2D, the following embodiment is described. Are preferable.

{Embodiment 2}
Referring to FIG. 11, one embodiment of a method for manufacturing a composite substrate according to the present invention includes a step of forming ion implantation region 20 i on one main surface side of group III nitride substrate 20, A step of forming a plurality of convex portions 31p having at least one type of planar shape capable of plane filling on one main surface side, and a main surface on the side where the ion implantation region 20i of the group III nitride substrate 20 is formed And a step of bonding the main surface of the different composition substrate 10 on which the convex portions are formed, and a group III nitride layer 21 bonded to the different composition substrate 10 in the ion implantation region 20i. And the remaining group III nitride substrate 22 is separated. According to the composite substrate manufacturing method of the present embodiment, the composite substrate 2D of Embodiment 1 can be manufactured extremely efficiently.

In the method for manufacturing a composite substrate of the present embodiment, at least one of the main surfaces of the different composition substrate 10 and the one main surface of the group III nitride substrate 20 is increased in bonding strength between them. It is preferable to form the bonding layers 31 and 32 on each other. The bonding layers 31 and 32 are not particularly limited, but from the viewpoint of increasing the bonding strength between the different composition substrate 10 and the group III nitride layer 21, a SiO ₂ layer, a ZnO layer, a TiO ₂ layer, a Ga ₂ O ₃ layer. A layer, a SnO ₂ layer, an In ₂ O ₃ layer, an Sb ₂ O ₃ film, an Sb ₂ O ₅ film, a TiN layer, etc. are preferably used.

(Ion implantation region forming process in group III nitride substrate)
Referring to (B1) of FIG. 11, preferably, a CVD (chemical vapor deposition) method, a sputtering method, a PVD (physical vapor deposition) method is provided on one main surface side of group III nitride substrate 20. The bonding layer 32 is formed by a plating method or the like.

  Next, referring to (B2) of FIG. 11, from one main surface side of group III nitride substrate 20 (when the bonding layer 32 is formed, the main surface side where the bonding layer 32 is formed), hydrogen By implanting ions I having a low mass number such as helium, an ion implantation region 20 i is formed in a region having a predetermined depth from the main surface of the group III nitride substrate 20. Such an ion implantation region 20i is embrittled as compared to other regions.

(Formation process of convex part in different composition substrate)
Referring to (A1) of FIG. 11, preferably, bonding layer 31 is formed on one main surface side of different composition substrate 10 by CVD, sputtering, PVD, plating, or the like.

  Next, referring to (A2) of FIG. 11, when the bonding layer 31 is formed, at least one type of planar shape capable of plane filling can be obtained by removing a part of the bonding layer 31 (removed portion 31d). A plurality of convex portions 31p having the shape are formed. In the step of forming the convex portion 31p, a method for removing a part of the bonding layer is not particularly limited, and a method of removing with a scriber, a method of removing with a laser, a method of removing with any of dry etching and wet etching, and the like. Are preferable.

  Further, when the bonding layer 31 is not formed on the different composition substrate 10, the different composition substrate 10 is removed by removing a part of one main surface side of the different composition substrate 10 using the same method as described above. It is also possible to directly form a plurality of convex portions 31p having at least one type of planar shape that can be planarly filled. However, in this method, since a method of removing a part of the different composition substrate 10 is restricted, the bonding layer 31 is formed on the different composition substrate 10 and the bonding layer 31 is patterned as described above. Thus, it is preferable to form a plurality of convex portions 31p.

  11 (B1) and (B2) shown in FIG. 11 (the step of forming the bonding layer and the ion implantation region in the group III nitride substrate) and the steps shown in FIG. 11 (A1) and (A2) ( Any of the bonding layer and the protrusion forming step in the different composition substrate may be performed first.

(Step of bonding the group III nitride substrate and the different composition substrate)
Next, referring to (C1) of FIG. 11, the main surface of the group III nitride substrate 20 on which the ion implantation region 20i is formed (specifically, the main surface of the bonding layer 32) and a different composition. The main surface of the substrate 10 on which the convex portions 31p are formed (specifically, the main surface of the convex portions 31p of the bonding layer 31) is bonded. Here, the bonding method is not particularly limited, but from the viewpoint of increasing the bonding strength, bonding is performed by pressing the surfaces into which OH groups of the bonding layer (for example, SiO ₂ layer) are introduced and then dehydrating. Preferred examples include a surface activation method and a high vacuum pressure bonding method in which the surfaces of the bonding layers are bonded by heating after pressure bonding in an ultrahigh vacuum.

  In this way, the bonding layer 30 formed on the group III nitride substrate 20 and the convex portion 31p of the bonding layer 31 formed on the different composition substrate 10 are integrated with each other to form the different composition from the group III nitride substrate 20. A bonded substrate 1DA bonded to the substrate 10 is obtained. A void is formed in the bonding film 30 of the obtained bonding substrate 1DA by the removed portion 31d of the bonding layer 31.

(Group III nitride substrate separation process)
Next, referring to (C1) and (C2) in FIG. 11, group III nitride substrate 20 is bonded to different composition substrate 10 in ion implantation region 20i by applying heat or stress to bonding substrate 1DA. The group III nitride layer 21 and the remaining group III nitride substrate 22 are separated. At this time, in the region where the protrusion 31p of the bonding layer 31 and the bonding layer 32 are bonded in the bonding film 30, the group III nitride substrate 20 is separated by the ion implantation region 20i, but the bonding layer 31 is removed in the bonding film 30. In the region where the portion 31d exists, the group III nitride substrate 20 is not separated. Thus, a composite substrate 2D in which a plurality of group III nitride tiles 21p are bonded to each other on the different composition substrate 10 with a plurality of protrusions 30p of the bonding film 30 interposed therebetween is obtained. In the obtained composite substrate 2D, a portion of the group III nitride layer 21 in a region corresponding to the removed portion 31d of the bonding layer 31 is removed (removed portion 21d), thereby forming a plurality of group III nitride tiles 21p. Has been.

{Embodiment 3}
Referring to FIG. 12, another embodiment of the method for manufacturing a composite substrate according to the present invention includes a step of forming ion implantation region 20 i on one main surface side of group III nitride substrate 20, and a group III nitride. A step of forming a plurality of convex portions 32p having at least one planar shape capable of plane filling on the main surface side of the substrate 20 where the ion implantation region 20i is formed; and an ion implantation region of the group III nitride substrate 20 The step of bonding the main surface on which the convex portion 32p on the side on which 20i is formed and one main surface of the different composition substrate 10 are bonded together, and the group III nitride substrate 20 is formed in the ion implantation region 20i with a different composition. Separating the group III nitride layer 21 bonded to the substrate 10 and the remaining group III nitride substrate 22. According to the composite substrate manufacturing method of the present embodiment, the composite substrate 2D of Embodiment 1 can be manufactured extremely efficiently.

In the method of manufacturing the composite substrate of the present embodiment, at least one of the main surfaces of the different composition substrate 10 and the one main surface of the group III nitride substrate 20 is increased in bonding strength between them. It is preferable to form the bonding layers 31 and 32 on each other. The bonding layers 31 and 32 are not particularly limited, but from the viewpoint of increasing the bonding strength between the different composition substrate 10 and the group III nitride layer 21, a SiO ₂ layer, a ZnO layer, a TiO ₂ layer, a Ga ₂ O ₃ layer. A layer, a SnO ₂ layer, an In ₂ O ₃ layer, an Sb ₂ O ₃ film, an Sb ₂ O ₅ film, a TiN layer, etc. are preferably used.

(Ion implantation region forming process in group III nitride substrate)
Referring to (B1) of FIG. 12, preferably, bonding layer 32 is formed on one main surface side of group III nitride substrate 20 by CVD, sputtering, PVD, plating, or the like.

  Next, referring to (B2) of FIG. 12, from one main surface side of group III nitride substrate 20 (when the bonding layer 32 is formed, the main surface side where the bonding layer 32 is formed) By implanting ions I having a low mass number such as helium, an ion implantation region 20 i is formed in a region having a predetermined depth from the main surface of the group III nitride substrate 20. Such an ion implantation region 20i is embrittled as compared to other regions.

(Protrusion forming step in group III nitride substrate)
Next, referring to (B3) of FIG. 12, when the bonding layer 32 is formed, at least one type of plane that can be plane-filled can be obtained by removing a part of the bonding layer 32 (removed portion 32d). A plurality of convex portions 32p having a shape are formed. In the step of forming the convex portion 32p, a method for removing a part of the bonding layer is not particularly limited. Are preferable.

  Further, when the bonding layer 32 is not formed on the group III nitride substrate 20, by removing a part of one main surface side of the group III nitride substrate 20 using the same method as described above, It is also possible to directly form the plurality of convex portions 32p having at least one type of planar shape that can be planarly filled in the group III nitride substrate 20. However, in this method, since a method for removing a part of the group III nitride substrate 20 is limited, the bonding layer 32 is formed on the group III nitride substrate 20, and the bonding layer 32 is patterned as described above. By doing so, it is preferable to form a plurality of convex portions 32p.

(Preparation process of different composition substrate)
Referring to (A1) of FIG. 12, preferably, bonding layer 31 is formed on one main surface side of different composition substrate 10 by CVD, sputtering, PVD, plating, or the like.

  12 (B1) to (B3) shown in FIG. 12 (a step of forming a bonding layer, an ion implantation region and a protrusion in the group III nitride substrate) and a step shown in FIG. Any of the bonding layer forming step in the composition substrate may be performed first.

(Step of bonding the group III nitride substrate and the different composition substrate)
Next, referring to (C1) of FIG. 12, the main surface (specifically, the bonding layer 32 of the III-nitride substrate 20 on which the convex portion 32p on the side where the ion implantation region 20i is formed is formed. The main surface of the convex part 32p) and one main surface of the different composition substrate 10 (specifically, the main surface of the bonding layer 31) are bonded together. Here, the method of bonding is the same as in the second embodiment.

  Thus, the bonding film 30 in which the protrusions 32p of the bonding layer 32 formed on the group III nitride substrate 20 and the bonding layer 31 formed on the different composition substrate 10 are integrated together has a different composition from the group III nitride substrate 20. A bonded substrate 1DB bonded to the substrate 10 is obtained. In the bonding film 30 in the obtained bonding substrate 1DB, a void is formed by the removed portion 32d of the bonding layer 32.

(Group III nitride substrate separation process)
Next, with reference to (C1) and (C2) of FIG. 12, group III nitride substrate 20 is bonded to different composition substrate 10 in ion implantation region 20i by applying heat or stress to bonding substrate 1DB. The group III nitride layer 21 and the remaining group III nitride substrate 22 are separated. At this time, in the region where the convex portion 32p of the bonding layer 32 and the bonding layer 31 are bonded in the bonding film 30, the group III nitride substrate 20 is separated by the ion implantation region 20i, but the bonding layer 32 is removed in the bonding film 30. In the region where the portion 32d exists, the group III nitride substrate 20 is not separated. Thus, a composite substrate 2D in which a plurality of group III nitride tiles 21p are bonded to each other on the different composition substrate 10 with a plurality of protrusions 30p of the bonding film 30 interposed therebetween is obtained. In the obtained composite substrate 2D, a portion of the group III nitride layer 21 in a region corresponding to the removed portion 32d of the bonding layer 32 is removed (removed portion 21d), thereby forming a plurality of group III nitride tiles 21p. Has been.

{Embodiment 4}
Referring to FIG. 13, still another embodiment of the method for manufacturing a composite substrate according to the present invention includes a step of forming an ion implantation region 20i on one main surface side of a group III nitride substrate 20, and a group III nitridation. A step of bonding the main surface of the physical substrate 20 on which the ion implantation region 20i is formed and one main surface of the different composition substrate 10; and the III-nitride substrate 20 in the ion implantation region 20i, and the different composition substrate 10 And a step of separating the group III nitride layer 21 bonded to the other group III nitride substrate 22 and a plurality of group III nitride layers 21 having at least one type of planar shape capable of plane filling. Separating the group III nitride tile 21p. According to the composite substrate manufacturing method of the present embodiment, the composite substrate 2D of Embodiment 1 can be efficiently manufactured.

In the method of manufacturing the composite substrate of the present embodiment, at least one of the main surfaces of the different composition substrate 10 and the one main surface of the group III nitride substrate 20 is increased in bonding strength between them. It is preferable to form the bonding layers 31 and 32 on each other. The bonding layers 31 and 32 are not particularly limited, but from the viewpoint of increasing the bonding strength between the different composition substrate 10 and the group III nitride layer 21, a SiO ₂ layer, a ZnO layer, a TiO ₂ layer, a Ga ₂ O ₃ layer. A layer, a SnO ₂ layer, an In ₂ O ₃ layer, an Sb ₂ O ₃ film, an Sb ₂ O ₅ film, a TiN layer, etc. are preferably used.

(Ion implantation region forming process in group III nitride substrate)
Referring to (B1) of FIG. 13, preferably, bonding layer 32 is formed on one main surface side of group III nitride substrate 20 by CVD, sputtering, PVD, plating, or the like.

  Next, referring to (B2) of FIG. 13, from one main surface side of group III nitride substrate 20 (when the bonding layer 32 is formed, the main surface side on which bonding layer 32 is formed), hydrogen By implanting ions I having a low mass number such as helium, an ion implantation region 20 i is formed in a region having a predetermined depth from the main surface of the group III nitride substrate 20. Such an ion implantation region 20i is embrittled as compared to other regions.

(Preparation process of different composition substrate)
Referring to (A1) of FIG. 13, preferably, bonding layer 31 is formed on one main surface side of different composition substrate 10 by CVD, sputtering, PVD, plating, or the like.

  13 (B1) and (B2) shown in FIG. 13 (a step of forming a bonding layer and an ion implantation region in the group III nitride substrate) and a step shown in FIG. 12 (A1) (in the different composition substrate). Any of the bonding layer forming step may be performed first.

(Step of bonding the group III nitride substrate and the different composition substrate)
Next, referring to FIG. 13C1, the main surface of the group III nitride substrate 20 on the side where the ion implantation region 20i is formed (specifically, the main surface of the bonding layer 32), and a different composition. One main surface of the substrate 10 (specifically, the main surface of the bonding layer 31) is bonded. Here, the method of bonding is the same as in the second embodiment.

  Thus, the bonding layer 30 formed on the group III nitride substrate 20 and the bonding layer 31 formed on the different composition substrate 10 are integrated to form the group III nitride substrate 20 and the different composition substrate 10. The bonded substrate 1 bonded together is obtained.

(Group III nitride substrate separation process)
Next, referring to (C1) and (C2) in FIG. 13, by applying heat or stress to bonding substrate 1, group III nitride substrate 20 is bonded to different composition substrate 10 in ion implantation region 20i. The group III nitride layer 21 and the remaining group III nitride substrate 22 are separated. In this way, the composite substrate 2 is obtained in which the group III nitride layer 21 is bonded to the different composition substrate 10 with the bonding film 30 interposed therebetween.

(Separation process to group III nitride tile)
Next, referring to (C3) of FIG. 13, by removing a part of the group III nitride layer 21 of the composite substrate 2 (removed portion 21d), a plurality of bonding films 30 on the different composition substrate 10 are removed. A composite substrate 2D is obtained in which a plurality of group III nitride tiles 21p are bonded together with convex portions 30p interposed. Here, the method of removing a part of the group III nitride layer 21 is not particularly limited, and a method of removing with a scriber, a method of removing with a laser, a method of removing with any of dry etching and wet etching, etc. are preferable. It is mentioned in.

[Composite wafer]
{Embodiment 5}
Referring to FIG. 2, an embodiment of a composite wafer according to the present invention includes a composite substrate 2D of Embodiment 1 and a group III nitride epitaxial layer 40 formed on a group III nitride layer 21 of the composite substrate 2D. And including. In the composite wafer 3D of the present embodiment, a plurality of group III nitride epitaxial tiles 40p are respectively formed on a plurality of group III nitride tiles 21p of the group III nitride layer 21 that are separated from each other. The group III nitride epitaxial layer 40 is constituted by the nitride epitaxial tile 40p. For this reason, the composite wafer 3D has a group III nitride epitaxial tile 40p and a group III nitride epitaxial layer 40 with high crystallinity. In addition, from the viewpoint of preventing warping and cracking of the composite wafer 3D, the group III nitride epitaxial tile 40p is preferably separated from each other.

  In the composite wafer 3D of the present embodiment, the method of forming the group III nitride epitaxial layer 40 on the group III nitride layer 21 (a plurality of group III nitride tiles 21p separated from each other) in the composite substrate 2D is particularly limited. However, from the viewpoint of growing a highly crystalline group III nitride epitaxial layer 40, MOVPE (metal organic chemical vapor deposition) method, MBE (molecular beam growth) method, HVPE (hydride vapor phase epitaxy) method, sublimation method A liquid phase method such as a gas phase method such as a flux method, a high nitrogen pressure solution method, or the like is preferable.

Example 1
1. Formation of Ion Implantation Region in Group III Nitride Substrate With reference to FIG. 11B1, two main surfaces having a diameter of 2 inches (5.08 cm) and a thickness of 500 μm formed by the HVPE method are (0001) planes ( A GaN substrate (group III nitride substrate 20) having a (Ga atom surface) and (000-1) plane (N atom surface) is prepared, and plasma CVD is performed on the N atom surface, which is one main surface of the GaN substrate. Thus, a SiO ₂ layer (bonding layer 32) having a thickness of 100 nm was formed.

Next, referring to FIG. 11B2, from the SiO ₂ layer (bonding layer 32) side on the N atom surface of the GaN substrate (Group III nitride substrate 20), about 200 nm from the N atom surface of the GaN substrate. Hydrogen ions (ion I) were implanted into the depth region. The hydrogen ion implantation conditions were an acceleration voltage of 50 keV and a dose of 7 × 10 ¹⁷ cm ⁻² .

2. Protrusion Formation in Different Composition Substrate Referring to FIG. 11A1, a sapphire substrate (different composition substrate) having a diameter of 2 inches (5.08 cm) and a thickness of 500 μm and one main surface being a (0001) plane. 10) was prepared, and an SiO ₂ layer (bonding layer 31) having a thickness of 100 nm was formed on the main surface ((0001) surface) of the sapphire substrate by plasma CVD.

Next, referring to (A2) of FIG. 11, by removing a part of the SiO ₂ layer (bonding layer 31) formed on the sapphire substrate (different composition substrate 10) by scribing, one side is 800 μm. The convex portions 31p having a regular triangular planar shape are arranged so as to perform planar filling as shown in FIG. 3 with an interval of a distance D between the groove-shaped removed portions 31d having a width of 20 μm.

3. Bonding of Group III Nitride Substrate and Different Composition Substrate Next, referring to FIG. 11 (C1), the main surface of the GaN substrate (Group III nitride substrate 20) on which the ion implantation region 20i is formed The SiO ₂ layer (bonding layer 32) formed on the (N atom surface) and the convex portion 31p of the SiO ₂ layer (bonding layer 31) formed on the main surface of the sapphire substrate (different composition substrate 10), By bonding by the surface activation method, the SiO ₂ layer (bonding layer 32) and the convex portion 31p of the SiO ₂ layer (bonding layer 31) are integrated to form the bonding film 30, and the sapphire substrate (different composition substrate) 10) and the GaN substrate (III-nitride substrate 20) were bonded to each other with the bonding film 30 interposed therebetween to obtain a bonded substrate 1DA. In the bonding film 30 of the obtained bonding substrate 1DA, a gap due to the removed portion 31d of the bonding layer 31 was formed.

4). Separation of Group III Nitride Substrate Next, referring to (C2) of FIG. 11, by applying stress to the bonding substrate 1DA, the GaN substrate (Group III nitride substrate 20) is replaced with the sapphire substrate in the ion implantation region 20i. The GaN layer (III nitride layer 21) bonded to the bonding film 30 formed on the (different composition substrate 10) and the remaining GaN substrate (remaining group III nitride substrate 22) were separated. In this way, a plurality of GaN tiles of a GaN layer (group III nitride layer 21) having a thickness of 200 nm are interposed on the sapphire substrate (different composition substrate 10) by interposing a plurality of protrusions 30p of the bonding film 30 having a thickness of 200 nm. A composite substrate 2D having a group III nitride tile) bonded thereto was obtained.

5. Growth of Group III Nitride Epitaxial Layer Referring to FIG. 2, on the plurality of GaN tiles (Group III nitride tiles) of the GaN layer (Group III nitride layer 21) of the composite substrate 2D obtained above, MOVPE A GaN epitaxial layer (group III nitride epitaxial layer 40) having a thickness of 5 μm was grown by the method. The grown GaN epitaxial layer (Group III nitride epitaxial layer 40) is a plurality of GaN epitaxial tiles (Group III nitride tile 21p) grown on the plurality of GaN tiles (Group III nitride tile 21p), respectively. Group III nitride epitaxial tiles 40p) were separated, and no warpage or cracks occurred in any of the GaN epitaxial tiles (Group III nitride epitaxial tiles 40p).

(Example 2)
In the formation of the convex portion 31p in the sapphire substrate (different composition substrate 10), the convex portion 31p having a regular hexagonal planar shape with a side of 800 μm is spaced apart by a distance D of the groove-shaped removal portion 31d having a width of 20 μm. A composite substrate 2D is manufactured in the same manner as in Example 1 except that the planar filling as shown in FIG. 4 is performed, and a GaN epitaxial layer (a group III nitride epitaxial layer 40 is formed on the composite substrate 2D. ). The grown GaN epitaxial layer (Group III nitride epitaxial layer 40) is a plurality of GaN epitaxial tiles (Group III nitride tile 21p) grown on the plurality of GaN tiles (Group III nitride tile 21p), respectively. Group III nitride epitaxial tiles 40p) were separated, and no warpage or cracks occurred in any of the GaN epitaxial tiles (Group III nitride epitaxial tiles 40p).

(Example 3)
In the formation of the convex portion 31p in the sapphire substrate (different composition substrate 10), the convex portion 31p having a regular square planar shape with a side of 800 μm is spaced apart by a distance D between the groove-shaped removed portions 31d having a width of 20 μm. A composite substrate 2D is manufactured in the same manner as in Example 1 except that the planar filling as shown in FIG. 9 is performed, and a GaN epitaxial layer (a group III nitride epitaxial layer 40 is formed on the composite substrate 2D. ). The grown GaN epitaxial layer (Group III nitride epitaxial layer 40) is a plurality of GaN epitaxial tiles (Group III nitride tile 21p) grown on the plurality of GaN tiles (Group III nitride tile 21p), respectively. Group III nitride epitaxial tiles 40p) were separated, and no warpage or cracks occurred in any of the GaN epitaxial tiles (Group III nitride epitaxial tiles 40p).

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1,1DA, 1DB bonded substrate, 2,2D composite substrate, 3D composite wafer, 10 different composition substrate, 20 group III nitride substrate, 20i ion implantation region, 21 group III nitride layer, 21d, 31d, 32d removed portion, 21p, 21q, 21r Group III nitride tile, 30 junction film, 30p, 31p, 32p convex portion, 31, 32 junction layer, 40 group III nitride epitaxial layer, 40p group III nitride epitaxial tile.

Claims (7)

A different composition substrate having a chemical composition other than the group III nitride, and a group III nitride layer bonded to the different composition substrate,
The group III nitride layer is a composite substrate that is separated into a plurality of group III nitride tiles having at least one type of planar shape capable of plane filling.   2. The composite substrate according to claim 1, wherein the planar shape of the group III nitride tile is at least one selected from the group consisting of a striped shape, a triangular shape, a quadrangular shape, and a hexagonal shape.   3. The composite substrate according to claim 1, wherein a length of a longest side of the group III nitride tile is 2000 μm or less. 4. The composite substrate according to claim 1, wherein the group III nitride tile has a dislocation density of 1 × 10 ⁷ cm ⁻² or less.   A composite wafer comprising the composite substrate according to claim 1 and a group III nitride epitaxial layer formed on the group III nitride layer of the composite substrate. A method for producing a composite substrate according to claim 1,
Forming an ion implantation region on one main surface side of the group III nitride substrate;
Forming a plurality of convex portions having at least one planar shape capable of planar filling on one main surface side of the different composition substrate;
Bonding the main surface of the group III nitride substrate on which the ion-implanted region is formed and the main surface of the different composition substrate on which the convex portions are formed;
Separating the group III nitride substrate into the group III nitride layer bonded to the different composition substrate and the remaining group III nitride substrate in the ion implantation region, and manufacturing a composite substrate Method. A method for producing a composite substrate according to claim 1,
Forming an ion implantation region on one main surface side of the group III nitride substrate;
Forming a plurality of convex portions having at least one planar shape capable of planar filling on a main surface side of the group III nitride substrate where the ion implantation region is formed;
Bonding the main surface on which the convex portion on the side where the ion-implanted region of the III-nitride substrate is formed and one main surface of the different composition substrate; and
Separating the group III nitride substrate into the group III nitride layer bonded to the different composition substrate and the remaining group III nitride substrate in the ion implantation region, and manufacturing a composite substrate Method.

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