WO2023047864A1 - 窒化物半導体基板及びその製造方法 - Google Patents

窒化物半導体基板及びその製造方法 Download PDF

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WO2023047864A1
WO2023047864A1 PCT/JP2022/031572 JP2022031572W WO2023047864A1 WO 2023047864 A1 WO2023047864 A1 WO 2023047864A1 JP 2022031572 W JP2022031572 W JP 2022031572W WO 2023047864 A1 WO2023047864 A1 WO 2023047864A1
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layer
nitride semiconductor
substrate
laminated
adhesive layer
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French (fr)
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一平 久保埜
和徳 萩本
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Shin Etsu Handotai Co Ltd
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Shin Etsu Handotai Co Ltd
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Priority to EP22872620.4A priority Critical patent/EP4407657A4/en
Priority to US18/691,782 priority patent/US20240387170A1/en
Priority to JP2023549420A priority patent/JP7652274B2/ja
Priority to CN202280061885.9A priority patent/CN117941030A/zh
Publication of WO2023047864A1 publication Critical patent/WO2023047864A1/ja
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    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
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    • C30—CRYSTAL GROWTH
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    • C30B29/403—AIII-nitrides
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Definitions

  • the present invention relates to a nitride semiconductor substrate and its manufacturing method.
  • the MOCVD method which is one of the semiconductor thin film manufacturing methods, is widely used because it is excellent in large diameter and mass production, and can form homogeneous thin film crystals.
  • Nitride semiconductors typified by GaN are expected as next-generation semiconductor materials that exceed the limits of Si as a material.
  • GaN has a high saturation electron velocity, making it possible to fabricate devices that can operate at high frequencies, and since it also has a large breakdown electric field, it can operate at high output. In addition, weight reduction, miniaturization, and low power consumption can be expected. In recent years, GaN HEMTs that can operate at high frequencies and high power have been attracting attention due to the demand for higher communication speeds, as typified by 5G, and higher power.
  • Patent Document 1 disclose a large-diameter substrate for epitaxial growth of GaN (hereinafter referred to as a support substrate for GaN) having a large diameter and a coefficient of thermal expansion close to that of GaN.
  • This support substrate for GaN comprises a support structure including a polycrystalline ceramic core, a first adhesion layer, a conductive layer, a second adhesion layer, and a barrier layer; It is composed of a single crystal silicon layer laminated on a silicon layer.
  • GaN support substrate By using this GaN support substrate, a GaN epitaxial substrate having a large diameter, a thick epitaxial layer, and no cracks can be produced.
  • the difference in thermal expansion coefficient from GaN is extremely small, warping is less likely to occur during GaN growth and cooling. Since there is no need to provide a layer, the epitaxial film formation time is shortened, and the cost of epitaxial growth can be greatly reduced.
  • the supporting substrate for GaN is made of ceramics, the substrate itself is very hard and is resistant to plastic deformation.
  • the present invention has been made to solve the above problems, and provides a nitride semiconductor substrate capable of improving the surface morphology of an AlN layer and suppressing the generation of pits on the surface of a nitride semiconductor epitaxial wafer, and a method of manufacturing the same. intended to provide
  • a nitride semiconductor substrate comprising a growth substrate and a nitride semiconductor thin film formed on the growth substrate,
  • the nitride semiconductor thin film includes an AlN layer formed on the growth substrate and a nitride semiconductor layer formed on the AlN layer, and
  • a nitride semiconductor substrate is provided, wherein the AlN layer has an average Y (yttrium) concentration of 1E15 atoms/cm 3 or more and 5E19 atoms/cm 3 or less.
  • the average Y concentration in the AlN layer is within this range, the surface morphology of AlN is not deteriorated, and thus a nitride semiconductor substrate in which the generation of pits on the surface is suppressed can be obtained.
  • the AlN layer has a thickness of 50 to 150 nm, and an average Y (yttrium) concentration in the nitride semiconductor thin film from directly above the growth substrate to 300 nm in the thin film growth direction is 1E15 atoms/cm 3 or more. , 5E19 atoms/cm 3 or less.
  • the AlN layer is sufficiently covered with the yttrium-containing region in the nitride semiconductor thin film, the AlN layer having good surface morphology is more reliably formed, and pits are generated on the surface of the nitride semiconductor thin film. can be suppressed.
  • the nitride semiconductor layer is preferably made of one or more of GaN, AlN, and AlGaN.
  • such a nitride semiconductor layer can be provided on the AlN layer.
  • the growth substrate is a composite substrate in which a plurality of layers are laminated and a single crystal silicon layer is formed on the composite substrate, and It is preferable that the nitride semiconductor thin film is formed on the single crystal silicon layer.
  • a nitride semiconductor epitaxial growth substrate having a large diameter, a thick epitaxial layer, and no cracks can be produced.
  • warping is less likely to occur during nitride semiconductor growth and cooling, so warping of the substrate after film formation can be controlled to be small.
  • the single crystal silicon layer preferably has a thickness of 100 to 500 nm.
  • the single crystal silicon layer can have such a thickness.
  • the composite substrate includes a polycrystalline ceramic core, a first adhesive layer laminated over the entire polycrystalline ceramic core, a second adhesive layer laminated over the first adhesive layer, and the second adhesive layer laminated over the entire first adhesive layer. a barrier layer laminated over the adhesive layer of 2, and It is preferable that the single-crystal silicon layer is formed on a planarization layer laminated only on one side of the composite substrate.
  • the composite substrate may have, between the first adhesive layer and the second adhesive layer, a conductive layer laminated over the entire first adhesive layer.
  • the composite substrate can be given conductivity as needed.
  • the composite substrate includes a polycrystalline ceramic core, a first adhesive layer laminated on the entire polycrystalline ceramic core, a barrier layer laminated on the entire first adhesive layer, and a rear surface of the barrier layer. and a conductive layer laminated to the back surface of the second adhesive layer, and
  • the single crystal silicon layer may be formed on a planarizing layer laminated on the surface of the barrier layer of the composite substrate.
  • a nitride semiconductor substrate using such a growth substrate does not generate a leak path due to the surface-side conductive layer of the growth substrate, and can have excellent high-frequency characteristics.
  • the composite substrate includes a polycrystalline ceramic core, a first adhesive layer laminated over the entire polycrystalline ceramic core, a conductive layer laminated on the back surface of the first adhesive layer, and the conductive layer.
  • the single crystal silicon layer may be formed on a planarizing layer laminated on the surface of the barrier layer of the composite substrate.
  • the conductive layer preferably includes a polysilicon layer.
  • the conductive layer preferably has a thickness of 150 to 500 nm.
  • the conductive layer can be such a layer.
  • the polycrystalline ceramic core preferably contains aluminum nitride.
  • the difference in thermal expansion coefficient from the nitride semiconductor can be made extremely small.
  • the first adhesion layer and the second adhesion layer include a tetraethylorthosilicate (TEOS) layer or a silicon oxide (SiO 2 ) layer, and the barrier layer includes silicon nitride.
  • TEOS tetraethylorthosilicate
  • SiO 2 silicon oxide
  • the first adhesive layer and the second adhesive layer have a thickness of 50 to 200 nm, and the barrier layer has a thickness of 100 to 350 nm.
  • the thicknesses of the first adhesive layer, the second adhesive layer, and the barrier layer can be such layers.
  • the planarization layer preferably contains tetraethylorthosilicate (TEOS) or silicon oxide (SiO 2 ) and has a thickness of 500 to 3000 nm.
  • TEOS tetraethylorthosilicate
  • SiO 2 silicon oxide
  • the planarization layer can be such a layer.
  • a method for manufacturing a nitride semiconductor substrate comprising a growth substrate and a nitride semiconductor thin film formed on the growth substrate, comprising: (1) preparing the growth substrate containing Y (yttrium); and (2) epitaxially growing an AlN layer on the growth substrate and further epitaxially growing a nitride semiconductor layer on the AlN layer. , including the step of forming the nitride semiconductor thin film, and In the step (2), the nitride semiconductor substrate is formed by diffusing Y in the growth substrate so that the average Y (yttrium) concentration in the AlN layer is 1E15 atoms/cm 3 or more and 5E19 atoms/cm 3 or less.
  • a manufacturing method is provided.
  • the growth substrate contains a predetermined amount of Y (yttrium) in this way, it is possible to diffuse Y of a predetermined concentration into the AlN layer relatively easily.
  • the thickness of the AlN layer is 50 to 150 nm, and the average Y (yttrium) concentration in the nitride semiconductor thin film from directly above the growth substrate to 300 nm in the thin film growth direction is 1E15 atoms/cm 3 or more, 5E19 atoms /cm 3 or less.
  • the AlN layer is sufficiently covered with the yttrium-containing region in the nitride semiconductor thin film, the AlN layer having good surface morphology is more reliably formed, and pits are generated on the surface of the nitride semiconductor thin film. can be suppressed.
  • the growth substrate comprises a polycrystalline ceramic core containing yttria (Y 2 O 3 ) as a bonding material, a first adhesive layer laminated on the entire polycrystalline ceramic core, and the first adhesive layer.
  • a composite substrate comprising a second adhesive layer laminated over the entire second adhesive layer and a barrier layer laminated over the second adhesive layer, a planarization layer laminated only on one side of the composite substrate, and the planarization a growth substrate composed of a single-crystal silicon layer formed on a layer, and forming the nitride semiconductor thin film on the single-crystal silicon layer;
  • the average Y (yttrium) concentration in the AlN layer is adjusted to 1E15 atoms/cm 3 or more and 5E19 atoms/cm 3 or less by adjusting the thickness of the barrier layer in advance.
  • the composite substrate may have a conductive layer laminated over the entire first adhesive layer between the first adhesive layer and the second adhesive layer.
  • the composite substrate can be given conductivity as needed.
  • the growth substrate comprises a polycrystalline ceramic core containing yttria (Y 2 O 3 ) as a bonding material, a first adhesive layer laminated on the entire polycrystalline ceramic core, and the first adhesive layer.
  • a composite substrate comprising a barrier layer laminated over the entire surface, a second adhesive layer laminated on the rear surface of the barrier layer, and a conductive layer laminated on the rear surface of the second adhesive layer; and a substrate for growth composed of a planarization layer laminated on the surface of the barrier layer and a single-crystal silicon layer formed on the planarization layer, and the nitride semiconductor on the single-crystal silicon layer; to form a thin film, and
  • the average Y (yttrium) concentration in the AlN layer may be adjusted to 1E15 atoms/cm 3 or more and 5E19 atoms/cm 3 or less by adjusting the thickness of the barrier layer in advance.
  • the growth substrate comprises a polycrystalline ceramic core containing yttria (Y 2 O 3 ) as a bonding material, a first adhesive layer laminated on the entire polycrystalline ceramic core, and the first adhesive layer.
  • the average Y (yttrium) concentration in the AlN layer may be adjusted to 1E15 atoms/cm 3 or more and 5E19 atoms/cm 3 or less by adjusting the thickness of the barrier layer in advance.
  • a nitride semiconductor substrate capable of improving the surface morphology of the AlN layer and suppressing the generation of pits on the surface of the nitride semiconductor epitaxial wafer, and a method of manufacturing the same. can.
  • FIG. 1 is a schematic diagram showing an example of a growth substrate used in the present invention
  • FIG. 4 is a SIMS profile of an epitaxial structure 1 on a GaN support substrate having a barrier layer of 100 nm in Example 1.
  • FIG. 3 is a SIMS profile of epistructure 2 on a GaN support substrate having a barrier layer of 200 nm in Example 1.
  • FIG. It is an example of an SEM image of the interface between the epitaxial layer of the nitride semiconductor substrate obtained in the example and the substrate for growth (epitaxial structure 1).
  • FIG. 10 is a SIMS profile of an epitaxial structure 1 on a GaN support substrate having a barrier layer of 1000 nm in Comparative Example 1.
  • FIG. 10 is a SIMS profile of an epitaxial structure 2 on a GaN supporting substrate having a barrier layer of 1000 nm in Comparative Example 1.
  • FIG. 4 is an SEM image (epitaxial structure 1) of the epi-substrate interface in Comparative Example 2.
  • FIG. 10 is a cross-sectional TEM image (epitaxial structure 1) of pits generated on the surface of the nitride semiconductor thin film in Comparative Example 2; 4 is a graph showing the relationship between the Y average concentration in the AlN layer and the number of pits on the surface of the GaN layer in two levels of epitaxial structures.
  • FIG. 4 is a graph showing the relationship between the average Y concentration in the AlN layer and the barrier layer thickness in two levels of epistructures.
  • FIG. 4 is a schematic diagram showing another example of the growth substrate used in the present invention.
  • FIG. 4 is a schematic diagram showing still another example of the growth substrate used in the present invention.
  • the inventors of the present invention conducted repeated studies on improving the surface morphology of the AlN layer in order to suppress the generation of pits on the surface of the epitaxial wafer.
  • the inventors have found that the surface morphology of the AlN layer can be improved and the generation of pits can be suppressed by increasing the temperature, thus completing the present invention.
  • the present invention provides a nitride semiconductor substrate comprising a growth substrate and a nitride semiconductor thin film formed on the growth substrate, wherein the nitride semiconductor thin film is formed on the growth substrate. and a nitride semiconductor layer formed on the AlN layer, wherein an average Y (yttrium) concentration in the AlN layer is 1E15 atoms/cm 3 or more and 5E19 atoms/cm 3 or less It is a nitride semiconductor substrate.
  • the present invention also provides a method for producing a nitride semiconductor substrate comprising a growth substrate and a nitride semiconductor thin film formed on the growth substrate, comprising: (1) the above-described method containing Y (yttrium) (2) forming the nitride semiconductor thin film by epitaxially growing an AlN layer on the growth substrate and epitaxially growing a nitride semiconductor layer on the AlN layer; and, in the step (2), diffusing Y in the growth substrate so that the average Y (yttrium) concentration in the AlN layer is 1E15 atoms/cm 3 or more and 5E19 atoms/cm 3 or less.
  • a method for manufacturing a nitride semiconductor substrate comprising: (1) the above-described method containing Y (yttrium) (2) forming the nitride semiconductor thin film by epitaxially growing an AlN layer on the growth substrate and epitaxially growing a nitride semiconductor layer on the AlN layer; and, in
  • FIG. 1 shows an example of the nitride semiconductor substrate of the present invention.
  • the nitride semiconductor thin film 40 is formed on the growth substrate 10, and the nitride semiconductor thin film 40 is formed with the AlN layer 20 formed on the growth substrate 10.
  • the nitride semiconductor substrate 100 of the present invention is characterized in that the AlN layer 20 contains a predetermined amount of yttrium, and the average Y (yttrium) concentration in the AlN layer 20 is 1E15 atoms/cm 3 or more and 5E19 atoms/cm 3 or less. be.
  • the average Y (yttrium) concentration in the AlN layer 20 By setting the average Y (yttrium) concentration in the AlN layer 20 to 1E15 atoms/cm 3 or more and 5E19 atoms/cm 3 or less, the surface morphology of the AlN layer is improved, and an epitaxial layer (nitride semiconductor layer 30 ) can suppress the occurrence of pits.
  • the average Y concentration in the AlN layer 20 is less than 1E15 atoms/cm 3 , a sufficient pit suppression effect cannot be obtained, and if it is higher than 5E19 atoms/cm 3 , the original characteristics of GaN cannot be obtained.
  • the method for measuring the average Y (yttrium) concentration is not particularly limited, it can be obtained, for example, by secondary ion mass spectrometry (SIMS).
  • SIMS secondary ion mass spectrometry
  • the AlN layer has a thickness of 50 to 150 nm, and the average Y (yttrium) concentration in the nitride semiconductor thin film from directly above the growth substrate to 300 nm in the thin film growth direction is It is preferably 1E15 atoms/cm 3 or more and 5E19 atoms/cm 3 or less.
  • the AlN layer is sufficiently covered with the yttrium-containing region in the nitride semiconductor thin film, the AlN layer having good surface morphology is more reliably formed, and pits are generated on the surface of the nitride semiconductor thin film. can be suppressed.
  • the nitride semiconductor layer formed on the AlN layer is preferably made of one or more of GaN, AlN, and AlGaN.
  • a layer or a layer in which a superlattice structure composed of AlGaN, AlN, and GaN is laminated on AlGaN is more preferable.
  • the total thickness of the nitride semiconductor thin film including the AlN layer and the nitride semiconductor layer is not particularly limited, but can be, for example, 0.5 to 20 ⁇ m, preferably 1 to 10 ⁇ m.
  • the substrate for growth is a composite substrate in which a plurality of layers are laminated and a single crystal silicon layer is formed thereon, and a nitride semiconductor thin film is formed on the single crystal silicon layer. preferable.
  • the substrate for growth it is more preferable to use a supporting substrate for GaN as described below.
  • the supporting substrate for GaN comprises, for example, a polycrystalline ceramic core 1, a first adhesive layer 2 laminated over the entire polycrystalline ceramic core 1, and a laminated entirety of the first adhesive layer 2, as shown in FIG. a composite substrate (supporting structure) comprising a conductive layer 3 coated, a second adhesive layer 4 laminated over the conductive layer 3, and a barrier layer 5 laminated over the second adhesive layer 4; It is composed of a planarizing layer 6 laminated only on one side of the composite substrate and a single crystal silicon layer 7 laminated on the planarizing layer 6 .
  • the conductive layer 3 and the first adhesive layer 2 are formed as needed, and do not necessarily exist, and may be formed only on one side.
  • the polycrystalline ceramic core 1 preferably contains aluminum nitride, is sintered with a sintering aid at a high temperature of, for example, 1800° C., and has a thickness of about 600-1150 ⁇ m. Basically, it is often formed with a thickness of the SEMI standard for the Si substrate.
  • the first adhesion layer 2 and the second adhesion layer 4 are layers including a tetraethylorthosilicate (TEOS) layer and/or a silicon oxide (SiO 2 ) layer, deposited by an LPCVD process, a CVD process, or the like, and are approximately It preferably has a thickness of 50-200 nm.
  • TEOS tetraethylorthosilicate
  • SiO 2 silicon oxide
  • the conductive layer 3 comprises polysilicon, is deposited by an LPCVD process or the like, and preferably has a thickness of about 150-500 nm. This is a layer for imparting electrical conductivity, and is doped with, for example, boron (B) or phosphorus (P).
  • the conductive layer 3 containing polysilicon is provided as required, and may be omitted or may be formed only on one side.
  • the barrier layer 5 comprises a silicon nitride layer, is deposited by an LPCVD process or the like, and preferably has a thickness of 100-350 nm.
  • the planarization layer 6 contains tetraethylorthosilicate (TEOS) or silicon oxide (SiO 2 ), is deposited by an LPCVD process or the like, and preferably has a thickness of about 500 nm to 3000 nm.
  • This planarizing layer is deposited to planarize the upper surface, and is made of an ordinary ceramic film material such as SiO2 , Al2O3 , Si3N4 , or silicon oxynitride ( SixOyNz ). There may be.
  • the monocrystalline silicon layer 7 preferably has a thickness of approximately 100-500 nm. This is the layer that serves as a growth surface for other epitaxial growth such as GaN and is bonded to the planarization layer 6 using a layer transfer process or the like.
  • each layer the manufacturing method, the materials used, etc. are not limited to the above values, and not all layers are necessarily present.
  • the GaN support substrate for example, as shown in FIG. a barrier layer 5 bonded over said first adhesive layer, a second adhesive layer 4 bonded to the back surface of said barrier layer, and a conductive layer 3 bonded to the back surface of said second adhesive layer. , a planarization layer 6 bonded only to the surface of the composite substrate, and a monocrystalline silicon layer 7 bonded to the planarization layer.
  • the support substrate for GaN substrate for growth
  • a conductive layer 3 bonded to the back surface of said first adhesive layer
  • a second adhesive layer 4 bonded to the back surface of said conductive layer, the front and side surfaces of said first adhesive layer and said conductive layer.
  • a composite substrate comprising side surfaces of a layer and a barrier layer 5 bonded to the side and back surfaces of said second adhesive layer; a planarization layer 6 bonded only to the surface of said composite substrate; and bonded to said planarization layer. It can be composed of a single-crystal silicon layer 7 formed by
  • a growth substrate containing Y (yttrium) is prepared (step (1)), and a nitride semiconductor thin film is epitaxially grown on the growth substrate.
  • Y in the growth substrate is diffused to bring the average Y (yttrium) concentration in the AlN layer within a predetermined range (step (2)).
  • Step (1) is a step of preparing a growth substrate containing Y (yttrium).
  • a growth substrate containing Y which is a substrate for epitaxial growth
  • the substrate for growth is not particularly limited as long as it contains Y, but for example, the support substrate for GaN described above can be used.
  • yttria Y 2 O 3
  • a bonding material eg, sintering aid
  • the thickness of the barrier layer (silicon nitride layer) of the prepared GaN support substrate in advance, the amount of yttrium diffused into the epitaxial layer in step (2) described later can be easily controlled. It is possible to more reliably keep the average Y concentration in the AlN layer within a predetermined range.
  • the thickness of the barrier layer can be, for example, 100 to 350 nm or less.
  • Step (2) is a step of forming a nitride semiconductor thin film by epitaxially growing an AlN layer on the growth substrate and then epitaxially growing a nitride semiconductor layer on the AlN layer.
  • Y in the growth substrate is diffused to set the average Y (yttrium) concentration in the AlN layer to 1E15 atoms/cm 3 or more and 5E19 atoms/cm 3 or less.
  • step (2) for example, an AlN layer (for example, 50 to 150 nm), an AlGaN layer (100 to 2000 nm), and a Group III nitride semiconductor thin film such as GaN are epitaxially grown on the GaN support substrate in an MOCVD reactor.
  • TMAl is used as an Al source
  • TMGa as a Ga source
  • NH3 as an N source
  • the carrier gas is N 2 and H 2 or either of them, and the process temperature is about 900 to 1200.degree.
  • the average Y concentration in the AlN layer is set in the range of 1E15 atoms/cm 3 or more and 5E19 atoms/cm 3 or less. With such an yttrium concentration, the surface morphology of AlN is improved, and the generation of pits can be suppressed.
  • the method of manufacturing a nitride semiconductor substrate of the present invention is not limited to the first aspect described above.
  • a Y source gas may be flowed during the epitaxial growth of the AlN layer, in addition to the method of diffusing the yttrium as described above.
  • a supporting substrate for GaN which is a substrate for epitaxial growth, was produced.
  • the supporting substrate for GaN comprises a polycrystalline ceramic core (aluminum nitride core), a first adhesion layer (silicon oxide layer) laminated entirely on the polycrystalline ceramic core, and laminated entirely on the first adhesion layer.
  • a conductive layer polysilicon layer
  • a second adhesion layer silicon oxide layer
  • a barrier layer silicon nitride layer laminated over the second adhesion layer.
  • a planarization layer (silicon oxide layer) laminated only on one side of the composite substrate; and a single-crystal silicon layer formed on the planarization layer.
  • the thickness of the barrier layer was set to three levels of 100 nm, 200 nm, and 350 nm.
  • Yttria Y 2 O 3
  • epitaxial growth of Group III nitride semiconductor thin films such as AlN, AlGaN, and GaN was performed on the prepared support substrate for GaN.
  • a GaN support substrate was placed in a wafer pocket called a satellite.
  • TMAl was used as an Al source
  • TMGa was used as a Ga source
  • NH3 was used as an N source.
  • the carrier gas was N2 and H2 , and the process temperature was 1200°C.
  • a supporting substrate for GaN was placed on the satellite, and when epitaxial growth was performed, AlN and AlGaN were deposited in order from the substrate side toward the growth direction, and then GaN was epitaxially grown. Two levels of epitaxial layer structures (epitaxial structures 1 and 2) were produced.
  • ⁇ Epitaxial structure 1> After forming an AlN layer with a thickness of 150 nm and an AlGaN layer with a thickness of 150 nm, a so-called superlattice structure was formed with a thickness of about 3 ⁇ m by repeatedly forming AlGaN, AlN, and GaN layers on the order of several nm. A GaN layer was formed thereon, and the total thickness of the epitaxial layers was 6.5 ⁇ m.
  • ⁇ Epitaxial structure 2> After forming an AlN layer with a thickness of 150 nm, an AlGaN layer with a thickness of about 1.5 ⁇ m was formed so that the Al composition decreases along the growth direction. A GaN layer was formed thereon, and the total thickness of the epitaxial layers was 5.5 ⁇ m.
  • a device layer was provided on the surface layer side of the epitaxial layer.
  • the device layers consist of a highly crystalline GaN layer (channel layer) for generating a two-dimensional electron gas with a thickness of about 400 nm, an AlGaN layer (barrier layer) for generating a two-dimensional electron gas with a thickness of about 20 nm, and an outermost layer with a thickness of about 3 nm.
  • a structure provided with a GaN layer (cap layer) was employed.
  • the barrier layer has an Al composition of 20%.
  • the number of pits on the surface was counted using a surface inspection measuring device and a microscope. Also, the Y (yttrium) concentration in the epitaxial layer was measured by SIMS analysis (secondary ion mass spectrometry). Also, the cross section of the interface between the epitaxial layer and the growth substrate was observed with a SEM (scanning electron microscope) to confirm the morphology of the AlN layer.
  • the thickness of the barrier layer was set to 500 nm, 800 nm and 1000 nm. Using these substrates, the same epitaxial growth (2 levels) and the same evaluation as in the example were carried out.
  • the average Y concentration in the AlN layer of the other nitride semiconductor substrates produced in Comparative Examples 1 and 2 was also below 1E15 atoms/cm 3 , and it was confirmed that the thicker the barrier layer, the lower the average Y concentration ( Figure 11).
  • FIG. 9 shows a TEM image of pits generated on the surface (in FIG. 9, (b) is an enlarged image of (a)).
  • the present invention is not limited to the above embodiments.
  • the above-described embodiment is an example, and any device having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect is the present invention. included in the technical scope of

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JP2013030763A (ja) * 2011-06-24 2013-02-07 Sumitomo Chemical Co Ltd トランジスタ用半導体基板、トランジスタ及びトランジスタ用半導体基板の製造方法
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JP2020505767A (ja) 2017-01-18 2020-02-20 クロミス，インコーポレイテッド パワーデバイス用の窒化ガリウムエピタキシャル構造

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US20130048939A1 (en) * 2011-08-22 2013-02-28 Invenlux Limited Light emitting device having group iii-nitride current spreading layer doped with transition metal or comprising transition metal nitride
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