JP4748924B2 - Semiconductor laminated structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor multilayer structure and a method for reducing dislocations in a group III nitride layer group, and more specifically, a semiconductor that can be suitably used for semiconductor elements such as photonic devices and electronic devices, and elements such as field emitters. The present invention relates to a layered structure and a method for reducing dislocations in a group III nitride layer group in manufacturing the device.
[0002]
[Prior art]
Group III nitride films are used as semiconductor films constituting semiconductor elements such as photonic devices and electronic devices. In recent years, group III nitride films are also attracting attention as semiconductor films constituting high-speed IC chips used for mobile phones and the like. Have been bathed. In particular, a group III nitride film containing Al is attracting attention as a short wavelength light emitting / receiving device and further as a material applied to a field emitter.
[0003]
The group III nitride film as described above is usually formed by MOCVD. Specifically, the substrate on which the group III nitride film is to be formed is placed on a susceptor provided in a predetermined reaction tube, and a heater embedded in a heating mechanism installed in or outside the susceptor To 1000 ° C. or higher. Then, a predetermined source gas is introduced into the reaction tube together with a carrier gas and supplied onto the substrate.
[0004]
Then, a thermochemical reaction occurs on the substrate, the source gases are decomposed into constituent elements, and the constituent elements react with each other, and a target group III nitride film is deposited on the substrate. Are manufactured. These group III nitride films are required to have a low dislocation density in order to obtain characteristics as designed when semiconductor elements are formed.
[0005]
However, since the melting point of the group III nitride material is relatively high, it is difficult to produce a bulk single crystal substrate from the group III nitride material. Therefore, the group III nitride film must be produced by heteroepitaxial growth on a bulk single crystal substrate of a different material system such as a sapphire single crystal substrate. In this case, due to the lattice constant difference between the bulk single crystal substrate and the group III nitride film, a relatively large amount of misfit dislocations are generated at these interfaces, and the group III due to the misfit dislocations. A large amount of dislocations was introduced into the nitride film, and the crystal quality was significantly deteriorated.
[0006]
From this point of view, a buffer layer formed at a low temperature is inserted between the substrate and the group III nitride film, or striped SiO 2₂ELO technology using a mask has been developed.
[0007]
[Problems to be solved by the invention]
However, in the case of using the buffer layer described above, dislocations based on the low crystallinity of the buffer layer itself are generated in the group III nitride film, and the dislocation density in the group III nitride film is increased. It could not be reduced sufficiently. In addition, the conventional ELO technology has a high material selectivity, and particularly when a group III nitride film containing a large amount of Al is formed, polycrystalline group III nitride is deposited on the mask, and epitaxial growth occurs. It was difficult to do.
[0008]
An object of the present invention is to provide a group III nitride layer group having low dislocations and excellent crystal quality, and to provide a method for reducing the dislocation of the group III nitride layer group to be formed.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides:
  Made of a single materialA substrate;
  A group III nitride layer group formed on the substrate;
  Formed directly on the substrate in the group III nitride layer group,Made of nitride excluding AlpGaqInrN (0 ≦ p, q, r ≦ 1, p + q + r = 1)An island-like or mesh-like intervening layer;
  A buffer layer formed on the substrate via the intervening layer;
  An underlayer containing 50 atomic% or more of Al with respect to the entire group III element formed on the buffer layer;It is related with the semiconductor laminated structure characterized by comprising.
[0010]
The present invention also provides:
Preparing a predetermined substrate;
Forming a group III nitride layer group on the substrate;
In the group III nitride layer group, forming an island-like or network-like intervening layer;
The present invention relates to a method for reducing dislocations in a group III nitride layer.
[0011]
As a result of intensive investigations to achieve the above object, the present inventors have intervened an intervening layer made of a predetermined material in the target group III nitride layer group, whereby the group III nitriding is performed. It has been found that the dislocation density in the portion of the physical layer group located above the intervening layer is significantly reduced compared to the portion located below the intervening layer.
[0012]
That is, by forming the intervening layer in the group III nitride layer group, dislocations propagated from below are prevented from propagating by the intervening layer immediately above the intervening layer, as in the case of ELO technology. In the group III nitride layer group, the dislocation density is remarkably reduced at least in the portion located above the intervening layer. In the opening, after propagating in the longitudinal direction in the opening of the intervening layer, some dislocations bend in the lateral direction along the upper surface of the intervening layer. Accordingly, the dislocation density is also reduced in the portion of the group III nitride layer group located above the opening of the intervening layer.
[0013]
Furthermore, by forming the intervening layer from a material having good material selectivity with the group III nitride, the group III nitride layer group exhibits good epitaxial growth on the intervening layer, and a polycrystalline portion is formed. Good crystal quality that does not contain is exhibited. As a result, according to the present invention, a semiconductor multilayer structure including a group III nitride layer group having a low dislocation density and excellent crystal quality can be obtained.
[0014]
As the intervening layer, it is preferable to use a metal, an alloy, an intermetallic compound, a nitride other than AlpGaqInrN (0 ≦ p, q, r ≦ 1, p + q + r = 1), or an oxide.
[0015]
Examples of the metal include Ti, Ni, W, Mo, Au, Pd, Pt, and Cu. Examples of the alloy include alloys containing Ti such as TiAl, TiGa and TiAu, alloys containing Ni such as NiAl, NiGa and NiAu, and alloys containing noble metals such as AuAl, AuGa, PtAl, PtGa and PtNi. Can do. In addition, as the intermetallic compound, TiAl₃TiGa₃, GaPt and TiNi₃Can be illustrated. Examples of the nitride include TiNx, BN, NiNx, and SiN. Furthermore, examples of the oxide include AlOx, TiOx, NiOx, and MgOx.
[0016]
The “Group III nitride layer group” is a collective term for a single group III nitride layer or a multilayer film structure in which a plurality of group III nitride layers are stacked, and the semiconductor element to be manufactured. Adopt an appropriate configuration according to the type.
[0017]
The intervening layer is preferably made of a material having a band gap larger than the band gap of the group III nitride layer group. Thereby, it can be made transparent in the light receiving and emitting wavelength region of the semiconductor laminated structure, and a highly efficient semiconductor device can be manufactured. When the group III nitride layer group is composed of a plurality of group III nitride layers, from a material having a band gap larger than the minimum band gap of at least one of the group III nitride layer group, The intervening layer is configured.
[0018]
Since the island-like or mesh-like intervening layer is spontaneously formed by combining a predetermined film forming method and heat treatment inside and outside the CVD apparatus, a photolithography process for forming another pattern can be omitted. . Therefore, the target low dislocation group III nitride layer group can be easily formed.
[0019]
The reason why the intervening layer spontaneously becomes island-like or mesh-like is not clear, but there are several reasons. The first reason is presumed that in the case of dissimilar material bonding, since the binding energy is small, three-dimensional growth is promoted, and an energetically stable island or network structure is exhibited. The second reason is that, for example, nitriding and / or oxidizing the surface of the substrate is promoted by the heat treatment after the thin film is formed, resulting in the formation of voids due to volume change, and the three-dimensional growth is promoted around these voids. Therefore, it is presumed that an island-like or mesh-like structure is exhibited.
[0020]
Further, the group III nitride layer group is preferably formed through an underlayer formed on the main surface of the substrate, preferably containing Al. Moreover, it is preferable to form a surface nitrided layer on the main surface of the substrate. Thereby, the effect of reducing the dislocation density of the group III nitride layer group is promoted, and even when the group III nitride layer group contains Al, the generation of cracks can be suppressed and the crystal quality can be improved.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments of the invention.
[0022]
1 to 4 are configuration diagrams showing specific examples of the semiconductor laminated structure of the present invention. Note that similar constituent elements are denoted by the same reference numerals. 1 to 4 have a buffer layer 2 and a base layer 3 on the main surface 1A of a predetermined base material 1, and are sequentially formed on the base layer 3. The semiconductor multilayer structures 10, 20, 30 and 40 shown in FIGS. The n-type conductive layer 4, the n-type clad layer 5, the light emitting layer 6, the p-type clad layer 7 and the p-type conductive layer 8 are provided, and a light emitting element structure is exhibited. The buffer layer 2 to the p-type conductive layer 8 constitute the group III nitride groups 15, 25, 35 and 45 in the present invention.
[0023]
The semiconductor laminated structure 10 shown in FIG. 1 has island-shaped intervening layers 9 that are isolated from each other on the main surface 1A of the substrate 1. The semiconductor stacked structure 20 shown in FIG. 2 has island-shaped intervening layers 9 that are also isolated from each other on the buffer layer 2. In addition, the semiconductor multilayer structure 30 shown in FIG. 3 has island-shaped intervening layers 9 that are isolated from each other on the base layer 3. In the semiconductor multilayer structure 40 shown in FIG. The island-shaped intervening layer 9 is isolated from each other.
[0024]
In any of the semiconductor laminated structures shown in FIGS. 1 to 4, since the above-described intervening layer 9 is included in the group III nitride layer group 15, 25, 35, and 45, as described above, it propagates from below. The dislocations that have occurred are prevented from propagating by the intervening layer 9, and some of the dislocations that have propagated through the opening 9A bend in the lateral direction. Therefore, the dislocation density of the regions A, B, C and D located above the intervening layer 9 in the group III nitride layer groups 15, 25, 35 and 45, particularly the portion corresponding to the portion immediately above the intervening layer 9 is significantly reduced. Is done. Further, as a result, a part of the dislocations can provide the semiconductor multilayer structures 10, 20, 30 and 40 having a low dislocation density and excellent crystal quality.
[0025]
Specifically, the dislocation density of the upper part of the intervening layer 9 of the semiconductor nitride layer group 15, 25, 35 and 45 is set to the lower side of the intervening layer 9 by adding preferable conditions as shown below. The dislocation density of the portion can be reduced to half. This effect becomes remarkable by increasing the Ga concentration in the upper portion of the intervening layer 9 in the semiconductor nitride layer groups 15, 25, 35 and 45.
[0026]
As described above, in the present invention, in order to suppress the formation of polycrystalline nitride and perform epitaxial growth of the group III nitride layer groups 15, 25, 35 and 45 to achieve good crystal quality, intervening The layer 9 is preferably composed of a metal, an alloy, an intermetallic compound, a nitride other than AlpGaqInrN (0 ≦ p, q, r ≦ 1, p + q + r = 1), or an oxide. As a result, the epitaxial growth of the group III nitride layer groups 15, 25, 35 and 45 can be realized more effectively, and a superior crystal quality can be realized.
[0027]
As described above, examples of the metal include Ti, Ni, W, Mo, Au, Pd, Pt, and Cu. Examples of the alloy include alloys containing Ti such as TiAl, TiGa and TiAu, alloys containing Ni such as NiAl, NiGa and NiAu, and alloys containing noble metals such as AuAl, AuGa, PtAl, PtGa and PtNi. Can do. In addition, as the intermetallic compound, TiAl₃TiGa₃, GaPt and TiNi₃Can be illustrated. Examples of the nitride include TiNx, BN, NiNx, and SiN. Furthermore, examples of the oxide include AlOx, TiOx, NiOx, and MgOx.
[0028]
The intervening layer 9 is preferably made of a material having a band gap larger than that of the group III nitride layer group 15, 25, 35 and 45. Thus, the semiconductor laminated structure 10, 20, 30, and 40 can be made transparent in the light receiving / emitting wavelength region, and a highly efficient semiconductor device can be manufactured.
[0029]
In the semiconductor multilayer structure shown in FIGS. 1 to 4, the group III nitride layer group 15, 25, 35 and 45 is constituted by the p-type conductive layer 8 from the buffer layer 2, so that at least one of these layers is included. The intervening layer 9 is made of a material having a band gap larger than the minimum band gap of the two layers. Specifically, diamond, CaF₂And nitrides such as BN, and oxides such as AlOx and MgOx.
[0030]
The thickness of the intervening layer 9 is not particularly limited, but is preferably set to 0.5 nm to 1000 nm, more preferably 0.5 nm to 100 nm. As a result, the suppression of dislocation propagation and the lateral bending can be realized more easily, and the dislocation density in the group III nitride layers 15, 25, 35 and 45 can be more effectively reduced. become able to.
[0031]
In addition, in the semiconductor laminated structures 10, 20, 30, and 40 shown in FIGS. 1-4, although the intervening layer 9 has shown the island-like structure, it can also show a network structure. The network structure is an island structure shown in FIGS. 1 to 4 connected to each other to be continuous, and has a plurality of openings that expose, for example, the base material 1 positioned below, and has a so-called network shape. Such a structure is said.
[0032]
Whether the intervening layer 9 has an island-like structure or a network structure depends on the thickness and manufacturing conditions of the intervening layer 9 and the type of layer that should form the underlying layer with respect to the intervening layer 9.
[0033]
The group III nitride groups 15, 25, 35 and 45 are formed when the group III nitride semiconductor device is manufactured using the semiconductor multilayer structures 10, 20, 30 and 40 shown in FIGS. It plays a role as a functional layer in order to exert the intended function added to the. Accordingly, the group III nitride layer groups 15, 25, 35 and 45 preferably have a composition of AlxGayInzN (0 ≦ x, y, z ≦ 1, x + y + z = 1). In the semiconductor multilayer structures 10, 20, 30, and 40 shown in FIGS. 1 to 4, the AlxGayInzN (0 ≦ x, y, z ≦ 1, x + y + z = 1) are appropriately selected and set within the range of the composition.
[0034]
The group III nitride layer group 10, 20, 30 and 40 may further contain additional elements such as B, Si, Ge, Zn, Be and Mg. Furthermore, it is possible to include not only elements added intentionally but also trace elements that are inevitably taken in depending on the film forming conditions and the like, as well as trace impurities contained in the raw materials and reaction tube materials. Further, the buffer layer 2 to the p-type conductive layer 8 constituting the group III nitride layer group can be formed using a known film forming method such as a CVD method.
[0035]
The underlayer 3 preferably contains Al. Specifically, it preferably contains 50 atomic% or more, more preferably 80 atomic% or more of Al based on the entire group III element constituting the underlayer, and particularly from AlN. It is preferable that the composition (Al content is 100 atomic%). Thus, when the underlayer 3 contains a relatively large amount of Al, the crystal quality of the underlayer 3 can be improved by appropriately adjusting the production conditions of the underlayer 3, and as a result, the group III nitride The crystal quality of the entire layer group can be improved. For example, when the underlayer 3 is formed using the MOCVD method, the crystal quality of the underlayer 3 can be maintained in a good state by setting the formation temperature to 1100 ° C. or higher.
[0036]
The substrate 1 is made of sapphire single crystal, ZnO single crystal, LiAlO.₂Single connection, LiGaO₂Single crystal, MgAl₂O₄Single crystal, oxide single crystal such as MgO single crystal, Si single crystal, group IV-IV single crystal such as SiC single crystal, GaAs single crystal, AlN single crystal, GaN single crystal, and AlGaN single crystal III-V single crystal, ZrB₂It can be composed of a known substrate material such as a boride single crystal.
[0037]
5 to 7 are configuration diagrams showing other specific examples of the semiconductor laminated structure of the present invention. Components similar to those of the semiconductor multilayer structure shown in FIGS. 1 to 4 are denoted by the same reference numerals.
[0038]
5 to 7 includes an underlying layer 3 on the main surface 1A of a predetermined substrate 1, and an n-type conductive layer formed sequentially on the underlying layer 3. 4, an n-type cladding layer 5, a light-emitting layer 6, a p-type cladding layer 7 and a p-type conductive layer 8 have a light-emitting element structure. The underlayer 3 to the p-type conductive layer 8 constitute the group III nitride layer groups 55, 65 and 75 in the present invention.
[0039]
In addition, a surface nitride layer 12 is formed on the main surface 1A of the base material 1, thereby improving the crystal quality of the entire group III nitride layer groups 55, 65 and 75 formed on the base material 1. And the dislocation density can be reduced.
[0040]
The surface nitrided layer 12 can be formed by placing the substrate 1 in an atmosphere containing active nitrogen such as ammonia, heating it to a predetermined temperature, and holding it for a predetermined time. The thickness of the surface nitride layer 12 is preferably 10 nm or less and 0.2 nm or more. The thickness is derived from a composition analysis by ESCA analysis in the thickness direction of the substrate 1. However, depending on the type of group III nitride layer group to be formed, it may be advantageous not to form the surface nitride layer 12.
[0041]
The semiconductor laminated structure 50 shown in FIG. 5 has island-shaped intervening layers 9 that are isolated from each other on the base material 1. The semiconductor multilayer structure 60 shown in FIG. 6 has island-shaped intervening layers 9 isolated from each other on the base layer 3, and the semiconductor multilayer structure 70 shown in FIG. 7 is isolated from each other in the base layer 3. It has the intervening layer 9 which consists of an island-like structure.
[0042]
In any of the semiconductor stacked structures shown in FIGS. 5 to 7, since the above-described intervening layer 9 is included in the group III nitride layer group 55, 65, and 75, as described above, it has propagated from below. The dislocation is prevented from propagating by the intervening layer 9, and a part of the dislocation propagated in the opening 9A is bent in the lateral direction. Therefore, the dislocation density of the regions E, F, and G located above the intervening layer 9 in the group III nitride layer groups 55, 65, and 75, particularly the portion located immediately above the intervening layer 9 is significantly reduced. As a result, it is possible to provide the semiconductor multilayer structures 50, 60 and 70 having a low dislocation density and excellent crystal quality.
[0043]
Specifically, the dislocation density of the upper part of the intervening layer 9 of the group III nitride layer group 55, 65 and 75 is set to 1 of the dislocation density of the lower part by adding preferable conditions as shown below. / 2 or less. Such a dislocation reduction effect becomes humble as the Ga concentration in the upper portion of the intervening layer 9 increases as described above.
[0044]
The intervening layer 9 is preferably made of a metal, an alloy, an intermetallic compound, a nitride other than AlpGaqInrN (0 ≦ p, q, r ≦ 1, p + q + r = 1), or an oxide.
[0045]
The intervening layer 9 is made of diamond, CaF, as described above.₂And a material having a band gap larger than that of the group III nitride layers 55, 65 and 75, such as nitrides such as BN and oxides such as AlOx and MgOx. Accordingly, the semiconductor laminated structures 50, 60 and 70 can be made transparent in the light emitting / receiving wavelength region, and a highly efficient semiconductor device can be manufactured.
[0046]
The thickness of the intervening layer 9 is preferably set to 0.5 nm to 1000 nm, more preferably 0.5 nm to 100 nm, as described above. As a result, the suppression of dislocation propagation and the bending in the lateral direction can be realized more easily, and the dislocation density in the group III nitride layer groups 55, 65 and 75 can be more effectively reduced. become.
[0047]
5 to 7, the intervening layer 9 can also have the above-described network structure instead of the island structure.
[0048]
The group III nitride groups 55, 65 and 75 preferably have a composition of AlxGayInzN (0 ≦ x, y, z ≦ 1, x + y + z = 1) in order to exhibit a function as a group III nitride semiconductor device. In the semiconductor multilayer structures 50, 60, and 70 shown in FIG. 5 to FIG. x, y, z ≦ 1, x + y + z = 1) are appropriately selected and set within the range of the composition.
[0049]
Also in this case, the group III nitride layer group can also contain additional elements such as B, Si, Ge, Zn, Be, and Mg. Furthermore, it is possible to include not only elements added intentionally but also trace elements that are inevitably taken in depending on the film forming conditions and the like, as well as trace impurities contained in the raw materials and reaction tube materials. Further, the underlying layer 3 to the p-type conductive layer 8 constituting the group III nitride layer group can be formed by using a known film forming method such as a CVD method.
[0050]
As described above, from the viewpoint of improving the crystal quality of the group III nitride layer groups 55, 65 and 75, the underlayer 3 preferably contains Al, specifically, the entire group III elements constituting the underlayer. On the other hand, it is preferable that Al is contained in an amount of 50 atomic% or more, more preferably 80 atomic% or more, and particularly preferably AlN (Al content is 100 atomic%).
[0051]
Moreover, the base material 1 can be comprised from well-known board | substrate materials, such as the sapphire single crystal mentioned above.
[0052]
【Example】
Hereinafter, the present invention will be described specifically by way of examples.
Example 1
A sapphire substrate with a diameter of 2 inches and a thickness of 430 μm is H₂SO_Four+ H₂O₂And then pre-treated with a MOCVD apparatus. H as carrier gas₂The substrate was heated to 1200 ° C. while flowing at a flow rate of 1 m / sec, and then triethylboron (TEB) and NH_ThreeWas flown at an average flow rate of 5 m / sec to form a BN layer as an intervening layer with a thickness of 10 nm. As a result of SEM observation, it was confirmed that the BN layer had an island structure.
[0053]
Next, the substrate temperature was set to 600 ° C., and a GaN layer as a buffer layer was grown to a thickness of 30 nm so as to cover the BN layer. Next, the substrate temperature is set to 1050 ° C., and trimethylgallium (TMG) and NH are formed on the GaN layer.₃Was flown at an average flow rate of 1 m / sec to form a GaN layer having a thickness of 1 μm as an underlayer.
[0054]
Next, an n-GaN conductive layer having a thickness of 2 μm and an n-Al layer having a thickness of 0.01 μm are sequentially formed on the GaN foundation layer._0.1Ga_0.9N cladding layer, 0.005 μm thick In_0.1Ga_0.9N light emitting layer, 0.2 μm thick p-Al_0.1Ga_0.9An N clad layer and a 0.2-μm thick p-GaN conductive layer were formed to produce a semiconductor multilayer structure as shown in FIG.
[0055]
When the dislocation density of the GaN underlayer located above the BN intervening layer was measured by TEM observation, it was 1 × 10 at the portion located immediately above the BN intervening layer.⁸/ Cm²It was found that a dislocation density of
[0056]
(Example 2)
The same pretreatment as in Example 1 was performed on a sapphire substrate having a diameter of 2 inches and a thickness of 430 μm, and then placed in an MOCVD apparatus. The substrate is then heated to 1200 ° C. and NH₃Was flown at a flow rate of 5 m / sec to form a surface nitrided layer having a thickness of 1 nm on the main surface of the substrate. Next, after forming a GaN underlayer having a thickness of 1 μm under the same conditions as in Example 1, an intervening layer having an island-like structure made of TiNx was formed on the GaN underlayer. Next, an n-GaN conductive layer to a p-GaN conductive layer were formed under the same conditions as in Example 1, and a semiconductor multilayer structure as shown in FIG. 6 was produced. When the dislocation density of the n-GaN conductive layer located above the TiNx intervening layer was measured by TEM observation, it was 5 × 10 at the portion located immediately above the TiNx intervening layer.⁷/ Cm²It was found that a dislocation density of
[0057]
(Example 3)
A diamond intervening layer having an island-like structure was formed in the GaN underlayer to produce a semiconductor multilayer structure as shown in FIG. The production conditions of each layer were set in the same manner as in Example 1, and the composition components and thicknesses of the respective layers were set in the same manner as in Example 1. When the dislocation density of the n-GaN conductive layer located above the diamond intervening layer was measured by TEM observation, it was found to be 5 × 10 5 at the portion located immediately above the diamond intervening layer.⁷/ Cm²It was found that a dislocation density of
[0058]
Example 4
The same pretreatment as in Example 1 was performed on a sapphire substrate having a diameter of 2 inches and a thickness of 430 μm, and then placed in an MOCVD apparatus. The substrate is then heated to 1200 ° C. and NH₃Was flown at a flow rate of 5 m / sec to form a surface nitrided layer having a thickness of 1 nm on the main surface of the substrate. Next, an AlOx intervening layer having an island-like structure is formed on the sapphire substrate, and a GaN underlayer to a p-GaN conductive layer are formed under the same conditions as in Example 1, and a semiconductor multilayer structure as shown in FIG. Was made.
[0059]
Al₂O_ThreeThe dislocation density of the n-GaN conductive layer located above the intervening layer was measured by TEM observation.₂O_Three1 × 10 at the part located directly above the intervening layer⁸/ Cm²It was found that a dislocation density of
[0060]
(Example 5)
Instead of forming the island-shaped TiN intervening layer on the sapphire substrate, the TiN intervening layer was formed in the GaN underlayer to produce a semiconductor laminated structure as shown in FIG. The production conditions for each layer were set in the same manner as in Example 2, and the composition components and thicknesses of the respective layers were set in the same manner as in Example 2. When the dislocation density of the n-GaN conductive layer located above the TiN intervening layer was measured by TEM observation, it was 5 × 10⁷/ Cm²It was found that a dislocation density of
[0061]
(Comparative Example 1)
A semiconductor multilayer structure was fabricated according to the conditions of Example 1 without forming a BN intervening layer. When the dislocation density of the GaN underlayer was measured by TEM observation, 1 × 10⁹/ Cm²It turned out to be.
[0062]
(Comparative Example 2)
A semiconductor multilayer structure was fabricated according to the conditions of Example 2 without forming a TiN intervening layer. When the dislocation density of the GaN underlayer was measured by TEM observation,
1 × 10⁹/ Cm²It turned out to be.
[0063]
As described above, as is apparent from the examples and comparative examples, by providing an interstitial layer of island-like structure in the group III nitride layer group composed of the p-GaN conductive layer from the GaN foundation layer, it is positioned above it. It can be seen that the dislocation density of the layer is significantly improved. Therefore, according to the present invention, it can be seen that a semiconductor multilayer structure having a low dislocation density and excellent crystal quality can be provided.
[0064]
The present invention has been described in detail based on the embodiments of the invention with specific examples. However, the present invention is not limited to the embodiments of the invention, and does not depart from the scope of the invention. All changes and modifications are possible.
[0065]
For example, in the specific examples shown in FIGS. 1 to 7, the base layer 3 is provided on the main surface 1 </ b> A of the substrate 1, but the base layer 3 is not an essential requirement of the present invention, and the base layer 3 is provided. Even in the absence, the object of the present invention can be sufficiently achieved. However, by providing the base layer 3, the crystal quality of the group III nitride layer group provided thereabove can be further improved. In particular, by forming the underlayer from AlGaN containing Al, the dislocation density of the group III nitride layer group provided above can be further reduced. Furthermore, the dislocation density of the group III nitride layer group can be further reduced by providing a plurality of the intervening layers.
[0066]
In the specific examples shown in FIGS. 1 to 7, the intervening layer is provided on the substrate 1 or the buffer layer 2, but the cladding layer or the cladding layer, or the light emitting layer or the light emitting layer. It can also be provided. However, since the dislocation density is improved above the intervening layer, in the latter case, the dislocation density of the cladding layer or the light emitting layer itself cannot be improved.
[0067]
Furthermore, a multilayer laminated film such as a strained superlattice can be provided in place of the buffer layer 2. Furthermore, it is also possible to produce a light emitting / receiving element with a short wavelength by increasing the Al composition in the semiconductor multilayer structure composed of the group III nitride layer group.
[0068]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a group III nitride layer group having low dislocations and excellent crystal quality, and to provide a method for reducing the dislocation of the group III nitride layer group to be formed. .
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an example of a semiconductor multilayer structure of the present invention.
FIG. 2 is a configuration diagram showing another example of a semiconductor multilayer structure according to the present invention.
FIG. 3 is a configuration diagram showing another example of a semiconductor multilayer structure according to the present invention.
FIG. 4 is a configuration diagram showing an example of a semiconductor multilayer structure according to the present invention.
FIG. 5 is a configuration diagram showing another example of a semiconductor multilayer structure according to the present invention.
FIG. 6 is a configuration diagram showing another example of a semiconductor multilayer structure according to the present invention.
FIG. 7 is a configuration diagram showing an example of a semiconductor multilayer structure according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base material, 2 Buffer layer, 3 Underlayer, 4 n-type conductive layer, 5 n-type clad layer, 6 Light emitting layer, 7 p-type clad layer, 8 p-type conductive layer, 9 Intervening layer, 9A Opening part, 10, 20, 30, 40, 50, 60, 70 Semiconductor multilayer structure, 15, 25, 35, 45, 55, 65, 75 Group III nitride layer group

Claims (4)

A substrate made of a single material ;
A group III nitride layer group formed on the substrate;
An island-like or network-like intervening layer made of a nitride excluding AlpGaqInrN (0 ≦ p, q, r ≦ 1, p + q + r = 1), which is directly formed on the substrate in the group III nitride layer group;
A buffer layer formed on the substrate via the intervening layer;
A semiconductor multilayer structure comprising: an underlayer containing 50 atomic% or more of Al with respect to the entire group III element formed on the buffer layer . 2. The semiconductor multilayer structure according to claim 1, wherein the band gap of the intervening layer is larger than the band gap of the group III nitride layer group. Wherein the thickness of the intervening layer is 0.5Nm～1000nm, semiconductor multilayer structure according to claim 1 or 2. The III nitride layer group, AlxGayInzN (0 ≦ x, y , z ≦ 1, x + y + z = 1) becomes and having a composition, a semiconductor multilayer structure according to any one of claims 1 to 3 .

Images