JP2007165576A - Base material for semiconductor device, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base material for a semiconductor device capable of obtaining a light emission device which has an excellent surface state, obtains high light emission efficiency by reducing a dislocation density, and has a large effective light emission wavelength range; and to provide its manufacturing method. <P>SOLUTION: The base material for the semiconductor device includes a substrate, a superlattice structural layer formed on the substrate, and a base layer for function element formation which is formed on the superlattice structural layer and composed of an AlGaN semiconductor compound. The superlattice structural layer has a periodical structure where not less than three lamination units are superimposed, which are composed of a first low crystalline layer including the AlGaN semiconductor compound lower in crystalline compared with the base layer for function element formation, and a second low crystalline layer including the AlGaN semiconductor compound larger in Al composition ratio compared with the first low crystalline layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor device substrate for obtaining a semiconductor device made of an AlGaN semiconductor compound and a method for manufacturing the same.

  Conventionally, group III-V nitrides such as gallium nitride (GaN) have been used as semiconductor materials for light emitting devices such as light emitting diodes (LEDs) and laser diodes (LDs). In recent years, it is also expected as a semiconductor material for electronic devices such as high-frequency devices and power devices. In particular, an AlGaN semiconductor compound which is a group III-V nitride containing Al is expected to be applied to an ultraviolet light emitting device because of its wide band gap.

  However, since the AlGaN semiconductor compound has such a property that a crystal having a large Al composition ratio includes a large amount of crystal defects such as dislocations in the crystal and its crystallinity is lowered. There is a problem that it is difficult to obtain a semiconductor device in which high crystal quality is achieved while being contained.

In order to solve such a problem, a method of forming an AlGaN semiconductor compound by an epitaxial lateral growth method, a crystal growth method called so-called ELO (Epitaxial Lateral overgrowth) has been proposed (see, for example, Patent Document 1). . In this crystal growth method, a crystal with reduced dislocation density is obtained by forming irregularities on the surface of the substrate or the surface of the underlying crystal layer grown on the substrate and growing the crystals on the surface having the irregularities. Is the method.
In addition, in order to obtain a crystal with reduced dislocation density, a method of growing a crystal through a mask formed by an appropriate method on a substrate or an underlying crystal layer grown on the substrate has been proposed ( For example, see Patent Document 2.)

  However, a crystal formed on a surface having irregularities or a crystal formed through a mask may have a low surface state or a crack in the substrate. There is a problem that it cannot be suitably used as a light emitting device or an electronic device.

JP 2000-124500 A JP-A-11-251253

  The present invention has been made on the basis of the circumstances as described above, and the object thereof is a wide effective that has a good surface state, and a sufficiently high luminous efficiency can be obtained by reducing the dislocation density. An object of the present invention is to provide a substrate for a semiconductor device and a method for producing the same, which can obtain a light emitting device having an emission wavelength range.

The substrate for a semiconductor device of the present invention includes a substrate, a superlattice structure layer formed on the substrate, and a functional element formation base layer made of an AlGaN semiconductor compound formed on the superlattice structure layer. Have
The superlattice structure layer includes a first low crystalline layer made of an AlGaN semiconductor compound having a lower crystallinity than the base layer for forming a functional element, and an AlGaN having a higher Al composition ratio than the first low crystalline layer. It is characterized in that it has a periodic structure in which three or more stacked units composed of a second low crystalline layer made of a semiconductor compound are stacked.

In the base material for a semiconductor device of the present invention, it is preferable that a low crystalline AlGaN compound layer is interposed between the functional element forming base layer and the superlattice structure layer.
In addition, it is preferable that a buffer layer is interposed between the substrate and the superlattice structure layer.
Furthermore, it is preferable that a groove is formed on the surface of the substrate.

  The substrate for a semiconductor device according to the present invention may have a configuration in which a plurality of lamination units each composed of a high crystalline AlGaN compound layer, a superlattice structure layer, and a low crystalline AlGaN compound layer are laminated.

A manufacturing method of a substrate for a semiconductor device of the present invention is a manufacturing method of the substrate for a semiconductor device described above,
A superlattice structure layer forming step of forming a superlattice structure layer on the substrate; and a step of forming a functional element forming base layer on the superlattice structure layer,
The superlattice structure layer forming step includes a step of alternately growing three or more stacked units of the first low crystalline layer and the second low crystalline layer at a temperature lower than the temperature at which the functional element forming base layer is formed. It is characterized by that.

  In the manufacturing method of the base material for semiconductor devices of this invention, it is preferable to have an etching process which forms a groove part in the surface of a board | substrate.

  According to the base material for a semiconductor device of the present invention, a sufficiently wide effective light emission wavelength range can be obtained basically by configuring a light emitting device with an AlGaN semiconductor compound, and a superstructure containing a specific periodic structure on the substrate. A functional element forming base layer is formed via the lattice structure layer, and the periodic structure of the superlattice structure layer alleviates the biaxial stress in the crystal plane constituting the substrate, thereby suppressing the generation of cracks in the substrate. In addition, since the dislocations inevitably generated due to the difference in lattice constant between the substrate and the layer made of the AlGaN semiconductor compound can be associated with each other and at least part of them can disappear, the functional element AlGaN semiconductor compound to be formed on this functional element forming base layer having a good surface state and a reduced dislocation density The Li Cheng-emitting device, dislocation density and has a good surface state can be assumed that a sufficiently large luminous efficiency is reduced is obtained.

  In addition, according to the substrate for a semiconductor device in which a groove is formed on the surface of the substrate, crystal growth in the plane direction is promoted so as to fill the groove when the AlGaN semiconductor compound constituting the superlattice structure layer is grown. Thus, the functional element forming base layer formed on the superlattice structure layer can be reduced in dislocation density, and eventually the light emitting device formed on the functional element forming base layer The dislocation density can be remarkably reduced, and a sufficiently high luminous efficiency can be obtained.

  Hereinafter, the base material for a semiconductor device of the present invention will be described.

[First Embodiment]
FIG. 1 is an explanatory cross-sectional view schematically showing a configuration of an example of a substrate for a semiconductor device of the present invention.
The substrate 10 for a semiconductor device has a light emitting device placed on a main surface of a flat substrate (hereinafter also referred to as “sapphire substrate”) 11 made of, for example, sapphire via a superlattice structure layer 15. The base layer 17 for functional element formation for growth is formed.
A buffer layer 12 and a highly crystalline AlGaN compound layer 13 are interposed between the sapphire substrate 11 and the superlattice structure layer 15 as necessary. Further, a low crystalline AlGaN compound layer 16 may be interposed between the superlattice structure layer 15 and the functional element forming base layer 17.

The main surface of the sapphire substrate 11 is, for example, a (0001) surface, and the material constituting the substrate is not limited to sapphire, but is a Si single crystal, a SiC single crystal, a GaN single crystal, a ZnO single crystal, LiAlO _2. A known single crystal such as a single crystal, a LiGaO ₂ single crystal, or an MgAl ₂ O ₄ single crystal can be used.

The buffer layer 12 is a buffer region layer interposed between the sapphire substrate 11 and the superlattice structure layer 15 and exhibits the effect of reducing the dislocation density of the superlattice structure layer 15.
The buffer layer 12 can be formed, for example, by crystal growth in a state where the substrate temperature of the sapphire substrate 11 is 400 to 800 ° C., preferably 500 to 550 ° C.

  The highly crystalline AlGaN compound layer 13 promotes crystal growth in the plane direction by growing the highly crystalline AlGaN compound layer 13 on the buffer layer 12 made of crystals deposited in an island shape. 11 is formed for the purpose of reducing dislocations generated at the interface between the buffer layer 12 and the composition ratio of the AlGaN semiconductor compound constituting the highly crystalline AlGaN compound layer 13 is, for example, a base for forming a functional element. The composition ratio of the layer 17 can be the same.

  The low crystalline AlGaN compound layer 16 is a layer for promoting crystal growth in the plane direction of the AlGaN semiconductor compound constituting the functional element forming base layer 17, and constitutes the low crystalline AlGaN compound layer 16. The composition ratio of the AlGaN semiconductor compound is, for example, the same as the composition ratio of the functional element forming base layer 17.

The functional element forming base layer 17 is an uppermost layer of the substrate 10 for a semiconductor device on which a light emitting device is formed, and is made of a highly crystalline Al _x Ga _1-x N semiconductor compound. is there.
The Al composition ratio x of the Al _x Ga _1-x N semiconductor compound constituting the functional element forming base layer 17 is the composition of the AlGaN semiconductor compound of the light emitting device to be formed on the functional element forming base layer 17. It can be selected appropriately according to the ratio.

The composition ratio x of Al in the Al _x Ga _1-x N semiconductor compound constituting the functional element forming the base layer 17, Al in AlGaN semiconductor compound constituting the light emitting device to be formed on the functional element forming the base layer 17 It is preferable that the composition ratio is larger than, for example, 0.01 to 0.25, and preferably 0.1 to 0.2. When the Al composition ratio x is less than 0.01, the absorption of ultraviolet light is increased, and therefore, when a light emitting device is produced, the light emission efficiency may be low. On the other hand, if the Al composition ratio x is greater than 0.25, the characteristics of Al are strongly manifested and a large number of dislocations are generated, and the resulting functional element forming base layer 17 has a high dislocation density. There is a possibility that the light emitting device formed on the forming base layer 17 cannot obtain a sufficiently high luminous efficiency.

  The superlattice structure layer 15 includes a first low crystalline layer made of an AlGaN semiconductor compound having a lower crystallinity than the AlGaN semiconductor compound constituting the functional element forming base layer 17, and the functional element forming base layer. A periodic structure in which three or more stacked units each composed of a second low-crystalline layer made of an AlGaN semiconductor compound having a lower crystallinity than 17 and an Al composition ratio larger than that of the first low-crystalline layer are stacked. It is what you have. The AlGaN semiconductor compound constituting the first low crystallinity layer can have, for example, the same composition as the AlGaN semiconductor compound constituting the functional element forming base layer 17.

The Al composition ratio y of the Al _y Ga _1-y N semiconductor compound constituting the second low crystalline layer of the superlattice structure layer 15 is the Al composition of the AlGaN semiconductor compound constituting the first low crystalline layer. For example, such a second low crystalline layer can be made of an AlN semiconductor compound having a composition ratio y of 1.0, for example. If the difference between the lattice constants of the first low crystalline layer and the second low crystalline layer is too small, the effect of reducing the dislocation density is not sufficiently exhibited. In some cases, the dislocation density may not be reduced.

  The thickness of the first low crystallinity layer and the second low crystallinity layer can be set to, for example, 1 to 50 nm and 1 to 10 nm, respectively.

The number of periods of this periodic structure is, for example, 3 to 20, preferably 5 to 15, and particularly preferably 10.
If the number of periods of this periodic structure is excessive, the manufacturing process becomes complicated, which is not industrially advantageous. On the other hand, when the number of periods of this periodic structure is too small, dislocations generated at the interface between the sapphire substrate 11 and the buffer layer 12 may not be sufficiently reduced.

  The substrate temperature relating to crystal growth of the first low crystalline layer and the second low crystalline layer constituting the superlattice structure layer 15 is preferably 900 to 950 ° C. The substrate temperature related to the crystal growth of the first low-crystalline layer and the second low-crystalline layer is in this range, so that the crystal growth in the plane direction is sufficiently promoted and good quality that can withstand practical use is obtained. Can be obtained.

  In the present invention, “high crystallinity” and “low crystallinity” relatively indicate the degree of crystallinity, and high crystallinity such as the functional element forming base layer 17 and the high crystallinity AlGaN compound layer 13. The crystalline layer is less than the first low crystalline layer, the second low crystalline layer, or the low crystalline crystalline layer such as the low crystalline AlGaN compound layer 16 constituting the superlattice structure layer 15. High crystallinity.

  The degree of crystallinity of these crystal layers is such that there are more defects in the low crystallinity crystal layer than in the high crystallinity crystal layer, the carrier density is low, and the resistance is high. It can be evaluated by the voltage dependency of the layer capacitance.

  In the semiconductor device substrate 10 of this example, a highly crystalline crystal layer can be obtained by crystal growth in a state where the substrate temperature of the sapphire substrate 11 is in a high temperature range of 1030 to 1100 ° C. . Moreover, a low crystalline crystal layer can be obtained by crystal growth in a state where the substrate temperature of the sapphire substrate 11 is in a low temperature range of 900 to 950 ° C.

  In the semiconductor device base 10 described above, for example, the sapphire substrate 11 has a thickness of, for example, 10 to 1000 μm, the buffer layer 12 has a thickness of, for example, 0.1 to 50 nm, and a highly crystalline AlGaN compound layer. 13 has a thickness of, for example, 50 to 500 nm, the superlattice structure layer 15 has a thickness of, for example, 50 to 1000 nm as a whole of the periodic structure, and the low crystalline AlGaN compound layer 16 has a thickness of, for example, 50 to 1000 nm. The functional element-forming base layer 17 has a thickness of 1 to 30 μm, for example.

The dislocation density on the surface of the substrate 10 for a semiconductor device in this example is, for example, in the range of 10 ⁷ to 10 ⁹ cm ⁻² .
In general, when the dislocation density of the light emitting device is 10 ¹⁰ cm ⁻² or less, the light emitting device can be used as a light emitting device or an electronic device having good properties.

  According to the base material 10 for a semiconductor device described above, a sufficiently wide effective light emission wavelength range can be basically obtained by constituting a light emitting device with an AlGaN semiconductor compound, and a specific periodic structure is contained on the sapphire substrate 11. The functional element forming base layer 17 is formed through the superlattice structure layer 15 and the superlattice structure layer 15 is composed of a low crystalline crystal layer, so that the growth in the plane direction is positive in the crystal growth. The dislocations inevitably generated due to the difference in the lattice constant between the sapphire substrate 11 and the buffer layer 12 are associated with each other and at least part of the dislocations can be eliminated, thereby reducing the dislocation density. Further, the biaxial stress in the crystal plane constituting the sapphire substrate 11 is relaxed by the periodic structure of the superlattice structure layer 15, and the sapphire substrate 11 In addition, the generation of cracks is suppressed, and abnormal growth in which only a part of the crystal grows large in the crystal layer formed on the sapphire substrate 11 is suppressed, so that the generation of dislocations is suppressed. The formation base layer 17 has a good surface state and a reduced dislocation density, and a light emitting device made of an AlGaN semiconductor compound to be formed on the functional element formation base layer 17 has a good surface state. In addition, a sufficiently large luminous efficiency with a reduced dislocation density can be obtained.

Although the embodiments of the present invention have been specifically described above, the embodiments of the present invention are not limited to the above examples, and various modifications can be made.
For example, on the main surface of the sapphire substrate 11 of the substrate 10 for a semiconductor device, for example, groove portions (not shown) made of a large number of grooves arranged in a stripe shape are formed.

The groove formed in the sapphire substrate 11 can have a bottom width of 2 μm and a depth of 100 nm, for example, for each groove. Further, for example, the bottom width may be 5 μm and the depth may be 300 nm, or the bottom width may be 7 μm and the depth may be 500 nm.
The period in which each groove is formed, that is, the width of the convex portion formed by two adjacent grooves can be set to 0.1 to 1000 μm, for example.

  The groove portion of the sapphire substrate 11 is formed by forming a resist pattern corresponding to the shape of the groove portion to be formed on the main surface of the sapphire substrate 11 by photolithography, and using the resist pattern as a mask. It can be obtained by etching the sapphire substrate 11 by ion etching (RIE) to form a groove, and then removing the resist pattern.

  By forming such a groove portion, the AlGaN semiconductor compound constituting the functional element forming base layer 17 is formed along the shape of the groove portion so that the growth in the surface direction is promoted. The dislocations in the element forming base layer 17 can associate with each other to reduce the dislocation density. Therefore, compared to the functional element forming base layer obtained by using a sapphire substrate whose main surface is flat, the dislocations can be reduced. A base layer for forming a functional element with a further reduced density can be obtained.

Further, for example, the substrate for a semiconductor device of the present invention may have a configuration in which a plurality of lamination units each composed of a highly crystalline AlGaN compound layer, a superlattice structure layer, and a low crystalline AlGaN compound layer are laminated. .
Specifically, for example, in the case of a configuration in which two stacked units are stacked, a first highly crystalline AlGaN compound layer, a first superlattice structure layer, and a main layer of a sapphire substrate via a buffer layer A first low-crystalline AlGaN compound layer is stacked in this order, and a second high-crystalline AlGaN compound layer, a second superlattice structure layer, and a second low-crystalline layer are formed on the first low-crystalline AlGaN compound layer. The functional AlGaN compound layers are laminated in this order, and the functional element forming base layer is formed on the second low crystalline AlGaN compound layer.

  In this way, according to the base material for a semiconductor device having a configuration in which a plurality of stack units each composed of a plurality of crystal layers are stacked, since the effect of reducing the dislocation density is exhibited repeatedly, a better surface state can be obtained, The dislocation density can be further reduced.

[Semiconductor device]
By providing a light emitting device structure having a quantum well structure, for example, on a functional element forming base layer of a substrate for a semiconductor device as described above, a semiconductor device such as an LED or an LD is manufactured.
Specifically, in the light emitting device structure, an n-type semiconductor layer made of an n-type AlGaN semiconductor compound doped with Si, a layer made of an AlGaInN semiconductor compound, and a layer made of an AlGaN semiconductor compound are alternately stacked two by two. The active layer and a p-type semiconductor layer made of a p-type AlGaN semiconductor compound doped with Mg are configured by connecting an n-electrode and a p-electrode to the n-type semiconductor layer and the p-type semiconductor layer, respectively. The n-type semiconductor layer is formed on the functional element forming base layer, so that the n-type semiconductor layer is interposed between the functional element forming base layer and the active layer. By stacking a phosphor having a wavelength conversion function on the upper surface of the light emitting device structure, a white light emitting LED can be obtained.

  EXAMPLES Examples carried out to confirm the effects of the present invention will be described below, but the present invention is not limited to these examples.

<Example 1>
This sapphire substrate was placed in an MOCVD apparatus, and the substrate temperature of the sapphire substrate was raised to 1150 ° C. while H ₂ was supplied as a carrier gas, and held for 10 minutes.
First, a flat mirror-polished (0001) plane sapphire substrate is placed in an MOCVD apparatus, and the substrate temperature of the sapphire substrate is raised to 1150 ° C. with H ₂ supplied as a carrier gas. Hold for a minute. Next, the substrate temperature is lowered to 500 ° C., and a buffer layer made of a GaN compound is grown to a thickness of 20 nm on the (0001) surface of the sapphire substrate while supplying TMG (trimethylgallium) and NH ₃ at 10 sccm and 5 slm, respectively. It was. Next, the substrate temperature is lowered to 950 ° C., a first low crystalline layer made of Al _0.17 Ga _0.83 N compound is grown to 30 nm on the buffer layer, and then a second low crystalline property made of AlN compound is grown. The operation of growing the layer to 2 nm is repeated 10 times to form a periodic structure of Al _0.17 Ga _0.83 N compound / AlN compound (hereinafter referred to as “superlattice structure layer forming step”), and then the substrate temperature is changed to 1050 again. The functional element forming base layer made of a highly crystalline Al _0.17 Ga _0.83 N compound is grown to a thickness of 4.5 μm (hereinafter referred to as “functional element forming base layer forming step”). Thereby, the base material (1) for semiconductor devices was produced.

When the dislocation density in the semiconductor device substrate (1) was measured by a transmission electron microscope (TEM), it was 4.0 × 10 ⁹ cm ⁻² .
Further, no cracks were observed on the surface of the functional element forming base layer, and no abnormal growth was observed.

<Example 2>
First, a striped resist pattern having a width of 5 μm and a period of 5 μm is formed on the (0001) surface of the sapphire substrate by photolithography to a thickness of 2 μm, and the resist pattern is used as a mask by the RIE method. Etching is performed on the (0001) plane to form a groove portion having a width of 5 μm and a depth of 300 nm at the bottom of each groove, and a period in which the groove is formed is 5 μm, and then removing the resist pattern. As a result, a sapphire substrate on which stripe-like grooves were formed was obtained.
This sapphire substrate was placed in an MOCVD apparatus, and the substrate temperature of the sapphire substrate was raised to 1150 ° C. while H ₂ was supplied as a carrier gas, and held for 10 minutes. Next, the substrate temperature is lowered to 500 ° C., and a buffer layer made of a GaN compound is grown to a thickness of 20 nm on the (0001) surface of the sapphire substrate while supplying TMG (trimethylgallium) and NH ₃ at 10 sccm and 5 slm, respectively. It was. Next, the substrate temperature is raised to 1050 ° C., TMG, TMA (trimethylaluminum) and NH ₃ are supplied onto the buffer layer at 20 sccm, 8 sccm, and 7 slm, respectively, and are made of a highly crystalline Al _0.17 Ga _0.83 N compound. A highly crystalline AlGaN compound layer is grown to a thickness of 100 nm (hereinafter referred to as “a process for forming a highly crystalline AlGaN compound layer”), and then the substrate temperature is lowered to 950 ° C. to form a layer on the highly crystalline AlGaN compound layer. A first low crystalline layer made of an Al _0.17 Ga _0.83 N compound having an Al composition ratio x of 0.17 is grown to 30 nm, followed by TMA (trimethylaluminum) and NH ₃ at 8 sccm and 7 slm, respectively. The operation of supplying and growing the second low crystalline layer made of the AlN compound to 2 nm was repeated 10 times to produce Al _0.17 G a _0.83 A superlattice structure layer having a periodic structure of N compound / AlN compound is formed (hereinafter referred to as “superlattice structure layer forming step”), and TMG, TMA (trimethylaluminum) is formed on the superlattice structure layer. ) And NH ₃ are supplied at 20 sccm, 8 sccm, and 7 slm, respectively, to grow a low crystalline AlGaN compound layer made of a low crystalline Al _0.17 Ga _0.83 N compound (hereinafter referred to as “low crystalline AlGaN compound layer forming step”). Then, the substrate temperature is raised again to 1050 ° C., and a functional element forming base layer made of a highly crystalline Al _0.17 Ga _0.83 N compound is formed on the low crystalline AlGaN compound layer to a thickness of 4.5 μm. (Hereinafter, referred to as “functional element-forming base layer forming step”), thereby producing a semiconductor device substrate (2).

When the dislocation density in the substrate for semiconductor device (2) was measured by a transmission electron microscope (TEM), it was 1.9 × 10 ⁹ cm ⁻² .
Further, no cracks were observed on the surface of the functional element forming base layer, and no abnormal growth was observed.

<Example 3>
After performing the low crystalline AlGaN compound layer forming step, the second high crystalline AlGaN compound layer forming step is performed under the same conditions as in Example 2 except that the thickness is 1.5 μm. And the second superlattice structure layer forming step and the second low crystalline AlGaN compound layer forming step are performed in the same manner as in Example 2 to obtain the second superlattice layer. A high crystallinity was obtained in the same manner as in Example 2 except that the structural layer and the second low crystalline AlGaN compound layer were obtained, and thereafter the functional element forming base layer was formed under the same conditions as in Example 2. A substrate (3) for a semiconductor device having two laminated units composed of a crystalline AlGaN compound layer, a superlattice structure layer, and a low crystalline AlGaN compound layer was produced.

When the dislocation density in the substrate for semiconductor device (3) was measured by a transmission electron microscope (TEM), it was 6.0 × 10 ⁸ cm ⁻² .
Further, no cracks were observed on the surface of the functional element forming base layer, and no abnormal growth was observed.

<Comparative Example 1>
A comparative semiconductor device substrate was prepared in the same manner as in Example 2 except that the superlattice structure layer forming step was performed at a substrate temperature of 1050 ° C.

When the dislocation density of the substrate for a semiconductor device for comparison was measured with a transmission electron microscope (TEM), it was 1.1 × 10 ¹⁰ cm ⁻² .
Moreover, generation | occurrence | production of the crack was observed on the surface of the base layer for functional element formation, and also abnormal growth was observed.

It is explanatory drawing which shows typically the structure in an example of the base material for semiconductor devices of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Base material 11 for semiconductor devices Sapphire substrate 12 Buffer layer 13 High crystalline AlGaN compound layer 15 Superlattice structure layer 16 Low crystalline AlGaN compound layer 17 Base layer for functional element formation

Claims (7)

A substrate, a superlattice structure layer formed on the substrate, and a functional element forming base layer made of an AlGaN semiconductor compound formed on the superlattice structure layer,
The superlattice structure layer includes a first low crystalline layer made of an AlGaN semiconductor compound having a lower crystallinity than the base layer for forming a functional element, and an AlGaN having a higher Al composition ratio than the first low crystalline layer. A base material for a semiconductor device, characterized by having a periodic structure in which three or more stacked units composed of a second low crystalline layer made of a semiconductor compound are stacked.   2. The substrate for a semiconductor device according to claim 1, wherein a low crystalline AlGaN compound layer is interposed between the functional element forming base layer and the superlattice structure layer.   The base material for a semiconductor device according to claim 1, wherein a buffer layer is interposed between the substrate and the superlattice structure layer.   4. A substrate for a semiconductor device according to claim 1, wherein a groove is formed on the surface of the substrate.   5. The semiconductor according to claim 2, wherein a plurality of stacked units each including a high crystalline AlGaN compound layer, a superlattice structure layer, and a low crystalline AlGaN compound layer are stacked. Base material for equipment. It is a manufacturing method of the substrate for semiconductor devices in any one of Claims 1-5,
A superlattice structure layer forming step of forming a superlattice structure layer on the substrate; and a step of forming a functional element forming base layer on the superlattice structure layer,
The superlattice structure layer forming step includes a step of alternately growing three or more stacked units of the first low crystalline layer and the second low crystalline layer at a temperature lower than the temperature at which the functional element forming base layer is formed. A method for producing a base material for a semiconductor device. 6. The method of manufacturing a substrate for a semiconductor device according to claim 5, further comprising an etching step of forming a groove on the surface of the substrate.

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