JP4743989B2 - Semiconductor device, method for manufacturing the same, and method for manufacturing a semiconductor substrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a nitride semiconductor device using, for example, a substrate having a (111) plane of silicon using a substrate rotated by 7.3 ± 3 degrees around the [01-1] axis from the silicon substrate (001) plane. Is formed by etching technique, and crystal growth of the nitride semiconductor film is performed on the groove, so that the semiconductor film has a (1-101) plane as a plane orientation, and The present invention relates to a method for manufacturing the substrate.
[0002]
[Prior art]
Up to now, using nitride semiconductor materials composed of GaN, InN, AlN and mixed crystal semiconductors thereof, sapphire substrate, GaN substrate, SiC substrate or silicon (111) substrate is used._xGa_1-xA light emitting element using an N crystal as a light emitting layer is manufactured. In particular, since a Si substrate having a large area and a constant quality can be obtained at a low cost as compared with other substrates, it is expected that the light-emitting element can be manufactured at a low cost by employing this. .
[0003]
[Problems to be solved by the invention]
However, when a nitride semiconductor is grown using a silicon (111) substrate, a nitride semiconductor film having a C-plane as a growth surface can be obtained, but this epitaxial semiconductor film has not been very good in flatness at the atomic level. .
[0004]
For example, an n-type cladding layer and a quantum well type In on these substrates_xGa_1-xWhen a light-emitting layer made of N and a p-type cladding layer are stacked to produce a semiconductor device with a fine structure, the non-flatness of the film causes the thickness of the light-emitting layer and the In composition to be non-uniform. Only a semiconductor light emitting device having an emission spectrum with a wide half-value width of 40 nm was obtained. Moreover, only the light output of such a light emitting element was inferior compared with the element on a sapphire substrate or a SiC substrate.
[0005]
Also, using these substrates, a GaN-based MESFET (Metal semiconductor) in which an electrode composed of a source, a drain and a gate is fabricated on a film obtained by growing a Si-doped GaN layer through a high resistance layer composed of an AlGaN layer. Field effect transistor), and also in GaN-based MODFET (Modulation dope Field effect transistor) in which Si is doped on the GaN channel layer, because of its low flatness, the channel layer interface has poor steepness. The mobility of electrons traveling in the channel layer is lowered by scattering, and a semiconductor element having good electrical characteristics with respect to the cutoff frequency or the like cannot be obtained.
[0006]
The present invention solves the above problems. That is, the present invention provides a high quality, flatness using a silicon substrate in order to increase the steepness by improving the flatness at the atomic level and improve the photoelectric characteristics of the device in the nitride semiconductor laminated structure. It is an object of the present invention to provide crystal growth of an excellent nitride epitaxial film.
[0007]
[Means for Solving the Problems]
  In one aspect, a semiconductor device according to the present invention includes a silicon substrate and a general formula In formed on the main surface of the silicon substrate._xGa_yAl_zN (provided that x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1), and a silicon substrate, The compound semiconductor layer is formed on the inclined surface, the groove having a surface inclined by 62 degrees from the main surface or a surface inclined in an arbitrary direction from this surface within 3 degrees as an inclined surface.The axis perpendicular to the slope is the c-axis of the compound semiconductor layer, and the growth surface of the compound semiconductor layer is a (1-101) facet plane.The
[0008]
  In another aspect, the semiconductor device according to the present invention has the general formula In_xGa_yAl_zN (however, x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1), and the compound semiconductor layer has a (100) plane. [01-1] It is formed using a silicon substrate having a principal surface composed of a surface rotated by 7.3 degrees around the axis, or a surface inclined within 3 degrees in any direction from this surface. The silicon substrate includes a groove having a (111) plane as a slope, and the compound semiconductor layer is formed on the slope.The axis perpendicular to the slope is the c-axis of the compound semiconductor layer, and the growth surface of the compound semiconductor layer is a (1-101) facet plane.The
[0009]
  The <0001> direction of the compound semiconductor layer is substantially perpendicular to the slope.NaIncidentally, having the (1-101) plane as the plane orientation means that the plane orientation of the main surface of the compound semiconductor layer is substantially the (1-101) plane.
[0010]
The semiconductor element is a semiconductor light emitting element having a light emitting layer (active layer), the compound semiconductor layer includes the light emitting layer (active layer), and the light emitting layer (active layer) has a (1-101) plane. As the plane orientation.
[0011]
  In one aspect, a method for manufacturing a semiconductor device according to the present invention includes the following steps. On the main surface of the silicon substrate, a groove having a surface inclined by 62 degrees from the main surface or a surface inclined in an arbitrary direction within 3 degrees from this surface as an inclined surface is formed. On this slope, the general formula In_xGa_yAl_zA compound semiconductor layer represented by N (where x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) is formed.Then, crystal growth of the compound semiconductor layer proceeds with the axis perpendicular to the slope as the c-axis of the compound semiconductor film, and the (1-101) facet plane of the compound semiconductor layer is formed as a plane.
[0012]
  In another aspect, the method for manufacturing a semiconductor element according to the present invention includes the following steps. A silicon substrate having a principal surface constituted by a surface rotated by 7.3 degrees around the [01-1] axis or a surface within a range tilted within 3 degrees in any direction from this surface. A groove having a (111) plane as a slope is formed on the main surface. On this slope, the general formula Al_xGa_yIn_zA compound semiconductor layer represented by N (where x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) is formed.Then, crystal growth of the compound semiconductor layer proceeds with the axis perpendicular to the slope as the c-axis of the compound semiconductor film, and the (1-101) facet plane of the compound semiconductor layer is formed as a plane.
[0013]
A plurality of the grooves may be provided on the Si substrate, and the compound semiconductor layers formed from the slopes of the grooves may be combined according to crystal growth.
[0014]
A step of removing the silicon substrate after forming the compound semiconductor layer may be provided.
[0015]
  In the method for manufacturing a semiconductor substrate according to the present invention, the main surface of the silicon substrate is a surface inclined by 62 degrees from the main surface, or a surface inclined within 3 degrees in any direction from this surface. Forming a plurality of grooves having a general formula In on the slope_xGa_yAl_zA step of forming a compound semiconductor crystal represented by N (where x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1), and a compound semiconductor formed from the slope of each groove A step of obtaining a continuous film-like compound semiconductor crystal by further growing and combining the crystals, and a semiconductor comprising the compound semiconductor crystal after removing the silicon substrate after obtaining the film-like compound semiconductor crystal Obtaining a substrate.Then, the growth of the compound semiconductor crystal proceeds with the axis perpendicular to the slope as the c-axis of the compound semiconductor crystal, and the (1-101) facet plane of the compound semiconductor crystal is formed as a plane.
[0016]
GaN is a crystal with a strong orientation, and in a normal method, it is c-axis oriented perpendicular to the main surface, and as a result, a crystal having a C surface as the main surface is obtained. It was difficult to obtain a crystal having a plane different from the C plane.
[0017]
Therefore, for example, with respect to a substrate rotated by 7.3 degrees around the [01-1] axis from the silicon substrate (001) surface, or a surface inclined within a range of 3 degrees in any direction from this surface In particular, SiO₂52, and the SiO₂Etching is performed on the opening portion having no mask made of 52 to form a groove having a (111) facet surface 61 having a relationship of 62 degrees from the off-substrate (main surface) 60, and a nitride system is formed on the surface. It has been derived from a number of experiments conducted by the inventors that the semiconductor film is grown epitaxially, with the (1-101) facet surface 70 of the GaN-based semiconductor used as the growth surface.
[0018]
The facet surface 70 is a surface having extremely excellent flatness, and a nitride semiconductor film having high flatness at the atomic level was obtained by performing growth using this substrate.
[0019]
Furthermore, in this case, by tilting the c-axis of the GaN film, the difference in thermal expansion coefficient between the silicon substrate and this substrate is reduced, so that cracks are less likely to occur,
As described above, when the (1-101) facet surface 70 is used as a growth surface of the semiconductor light emitting device, the electric field generated by the piezoelectric effect at the well and barrier layer interface in the active layer is reduced by inclining the C axis. As a result, the carrier recombination probability of the electron-hole pair is increased, resulting in an increase in luminous efficiency.
[0020]
Therefore, using this film, a semiconductor light emitting device made of an AlGaInN-based nitride semiconductor in the shape of the semiconductor film was manufactured, and its characteristics were measured. As a result, a semiconductor light emitting device having a narrow full width at half maximum of 15 nm in the emission spectrum was obtained because the active layer was extremely flat and the fluctuation of the layer thickness was small.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to embodiments.
[0022]
<Embodiment 1>
FIG. 1 is a conceptual diagram for forming a (1-101) facet surface 70 of a nitride semiconductor film in the present embodiment, and FIG. 2 is a schematic cross-sectional view showing the structure of the nitride semiconductor light emitting device. The nitride semiconductor light emitting device of the present embodiment is partially formed on the 7.3 ° (001) Si off substrate 1 in the [0-1-1] direction.₂52, and the SiO₂Etching is performed on the portion having no mask made of 52 to form a groove having the (111) facet surface 61 of 62 degrees from the off-substrate (main surface) 60, and from the facet surface 61, the following As described, the n-AlGaInN layer 10 is sequentially flattened and stacked, the first cladding layer 2 made of n-GaInN, and In._xGa_1-xThe light emitting layer 3 is made of N, the carrier block layer 4 is made of p-AlGaInN, and the second cladding layer 5 is made of p-GaInN. Furthermore, an electrode 15 is provided on the lower surface of the silicon substrate, a transparent electrode 16 is provided on the upper surface of the second cladding layer 5, and a bonding electrode 17 is provided on a part of the upper surface of the transparent electrode 16. In FIG. 2, SiO₂The structure of the mask 52 and the groove is omitted.
[0023]
In_xGa_1-xN light emitting layer is Ga_xIn_1-xBy changing the composition x of N, the wavelength of interband emission can be emitted from ultraviolet to red, but in this embodiment, the composition of the Ga solid phase is X = 0.82 and emitted in blue To do. Magnesium-doped p-conducting type second cladding layer 5 has a high resistance. Therefore, even if a current, that is, holes are injected only from the bonding electrode 17 into one end of the second cladding layer 5, the current density may not be uniform over the entire area of the light emitting layer 3. Therefore, a thin film transparent electrode 16 is provided between the electrode 17 and the second cladding layer 5 over almost the entire surface of the second cladding layer 5, and more light can be extracted from this portion. A metal may be used for the electrode 15 connected to the n-conductivity type silicon substrate, and it is desirable to include any of Al, Ti, Zr, Hf, V, and Nb. For the transparent electrode 16 connected to the p-conductivity-type GaN second cladding layer 5, a metal having a thickness of 20 nm or less may be used. Ta, Co, Rh, Ni, Pd, Pt, Cu, Ag, Au It is desirable to include any of the following.
[0024]
Next, the manufacturing method of the light emitting element of this embodiment is demonstrated, also referring FIG.
First, the silicon substrate is cleaned, and a silicon oxide film or a silicon nitride film 52 is deposited thereon to a thickness of 100 nm using a sputtering or CVD technique. Thereafter, by performing a photolithographic technique, the silicon oxide film or the silicon nitride film is partially removed in a stripe shape. Further, a groove having a Si (111) facet surface 61 is formed on the wafer by acid etching such as buffered hydrofluoric acid. This groove is a stripe-shaped groove extending in the Si [01-1] direction. As shown in FIG. 1, the (111) facet surface 61 has a relationship of 62 degrees with the main surface 60 of the silicon substrate having the predetermined plane orientation. This surface can be easily formed by appropriately adjusting the temperature of a conventionally known acid etchant and appropriately adjusting the etching rate. It can also be easily formed by using an alkali etchant such as KOH. Further, in order to preferentially perform crystal growth from the predetermined (111) facet surface 61 on the groove and the surface of the Si substrate, the region other than the exposed region is made of silicon nitride, silicon oxide or the like. It is preferable to mask with a material that suppresses the growth of the nitride semiconductor thereon.
[0025]
Then, a nitride semiconductor film is grown on the substrate under the following growth conditions using MOCVD (metal organic chemical vapor deposition).
[0026]
When this substrate is used, crystal growth proceeds with the axis perpendicular to the facet surface 61 having a relation of 62 degrees from the silicon substrate as the c-axis of the nitride semiconductor film as shown in FIG. The (1-101) facet surface of the semiconductor film is formed as a plane 70.
[0027]
The silicon substrate used here was tilted 7.3 ° [0-1-1] from the (001) plane, that is, rotated by 7.3 degrees around the [01-1] axis from the (001) plane. The plane 60 has a plane 60, and the plane 70 can have substantially the same plane orientation as the main surface 60 of the silicon substrate. Even when tilted in an arbitrary direction within 3 degrees from this plane, an extremely flat GaN plane having a substantially (1-101) plane was obtained. As shown in FIG. 1, a nitride semiconductor film may be grown only on the trench, and a light emitting device structure may be formed continuously on the (1-101) facet surface 70 of the nitride semiconductor film. When film growth is continued, crystal growth proceeds gradually as shown in the left to right diagrams in FIG. 3, and a semiconductor light emitting device can be formed on the continuous film. In the present embodiment, an element is formed on the continuous film thus obtained.
[0028]
First, the silicon substrate 1 having grooves formed by the process described above is introduced into an MOCVD apparatus, and hydrogen (H₂) Cleaning is performed at a high temperature of about 1100 ° C. in an atmosphere.
[0029]
After that, N as carrier gas₂NH at 800 ° C. while flowing 10 l / min._ThreeAnd trimethylaluminum (TMA), trimethylindium (TMI), SiH_Four(Silane) gas was introduced at 5 l / min., 10 μmol / min., 17 μmol / min. 0.1 μmol / min., Respectively, and silicon-doped Al having a thickness of about 10 nm._0.85In_0.15N layer 10 is grown.
[0030]
Subsequently, at the same temperature, the supply of TMA was stopped, and trimethylgallium (TMG), TMI, SiH_Four(Silane) gas was introduced at about 20 μmol / min., 100 μmol / min., 0.05 μmol / min., Respectively, and silicon-doped Ga having a thickness of about 3 microns._0.92In_{0.0 8}N first clad layer 2 is grown.
[0031]
As a result, the groove is filled and further adjacent to Ga._0.92In_0.08N first cladding layers 2 are connected to each other, and a Ga substrate having a flat (1-101) surface 70 on a Si substrate._0.92In_0.08An N first cladding layer 2 is formed.
[0032]
The first cladding layer 2 may be formed as a GaN film by raising the growth temperature after depositing the AlInN intermediate layer 10, but by using a GaInN cladding layer that contains In but does not contain Al. Therefore, low temperature growth was possible without raising the growth temperature to high temperature, and in this case, the generation of cracks was small.
[0033]
Thereafter, the supply of TMA, TMI, and TMG was stopped, the substrate temperature was lowered to 760 ° C., and trimethylindium (TMI), which is an indium raw material, was introduced at 6.5 μmol / min., And TMG was introduced at 2.8 μmol / min. And In_0.18Ga_0.82A 3 nm thick well layer made of N is grown. Thereafter, the temperature is raised again to 850 ° C., TMG is introduced at 14 μmol / min, and a barrier layer made of GaN is grown. Similarly, the growth of the well layer and the barrier layer is repeated to grow the light emitting layer 3 composed of four pairs of multiple quantum wells (MQW).
[0034]
After the growth of the light emitting layer is completed, at the same temperature as the last barrier layer, TMG is 11 μmol / min., TMA is 1.1 μmol / min., TMI is 40 μmol / min. Pentadienyl magnesium (Cp₂Mg) was flowed at 10 nmol / min., 50 nm thick p-type Al_0.20Ga_0.75In_0.05N carrier block layer 4 is grown. When the growth of the carrier block layer 4 is completed, the supply of TMA is stopped at the same growth temperature, and the p-type Ga having a thickness of 80 nm is stopped._0.9In_0.1The growth of the light emitting device structure is completed by growing the N second cladding layer 5. When growth is complete, TMG, TMI and Cp₂After stopping the supply of Mg, it is cooled to room temperature and taken out from the MOCVD apparatus. Then p-type Ga_0.9In_0.1The transparent electrode 16 is formed on the upper surface of the second cladding layer made of the N layer, the bonding electrode 17 is formed on a part of the transparent electrode 16, and the electrode 15 is formed on the lower surface of the Si substrate, whereby the light emitting device of this embodiment is completed.
[0035]
And the characteristic of the produced semiconductor element was measured. As a result, a semiconductor light emitting device having a narrow full width at half maximum of 15 nm in the emission spectrum was obtained because the active layer was extremely flat and the fluctuation of the layer thickness was small. In addition, the emission intensity was 10 times or more as compared with the element formed on the Si (111) substrate which is the prior art.
[0036]
<Embodiment 2>
In the first embodiment, the light emitting element structure is directly fabricated on a silicon substrate inclined 7.3 degrees from the (001) plane. This silicon off substrate is used as a base substrate for fabricating a GaN substrate. It was also possible to fabricate a semiconductor element using a flat GaN substrate obtained by removing.
[0037]
Using MOCVD (metal organic chemical vapor deposition), GaN is once grown on this Si off substrate using an AlN intermediate layer. However, similar results were obtained even when an AlInN or AlGaN intermediate layer was used for this intermediate layer.
[0038]
The substrate is introduced into an HVPE (hydride VPE) apparatus. N₂Carrier gas and NH_ThreeThe substrate temperature is raised to about 1050 ° C. while flowing 5 l / min. Thereafter, GaCl is introduced at 100 cc / min on the substrate to start the growth of a GaN thick film. GaCl is generated by flowing HCl gas through Ga metal maintained at about 850 ° C. In addition, impurities can be arbitrarily doped during growth by flowing an impurity gas by using an impurity doping line that is individually connected to the vicinity of the substrate. In this example, for the purpose of doping Si, at the same time as starting growth, monosilane (SiH_Four) 200 nmol / min. (Si impurity concentration approx. 3.8x10)¹⁸cm^-3) To grow a Si-doped GaN film.
[0039]
By the above method, growth was performed for 8 hours, and GaN having a total thickness of about 350 μm was grown on the Si substrate. After the growth, the Si substrate is removed by polishing or etching to obtain a very flat GaN substrate having a (1-101) plane. Thus, according to the present embodiment, a GaN substrate having a (1-101) plane on the surface can be obtained.
[0040]
Then, after this cleaned GaN substrate is introduced into the MOCVD apparatus, the substrate temperature is raised to 760 ° C. on the GaN substrate, and trimethylindium (TMI) as an indium raw material is 6.5 μmol / min., TMG. Then, a well layer having a thickness of 3 nm made of In0.18Ga0.72N is grown. Thereafter, the temperature is raised again to 850 ° C., TMG is introduced at 14 μmol / min, and a barrier layer made of GaN is grown. Similarly, the growth of the well layer and the barrier layer is repeated to grow the light emitting layer 3 composed of four pairs of multiple quantum wells (MQW).
[0041]
After the growth of the light emitting layer is completed, at the same temperature as the last barrier layer, TMG is 11 μmol / min., TMA is 1.1 μmol / min., TMI is 40 μmol / min. Pentadienyl magnesium (Cp₂Mg) was flowed at 10 nmol / min., 50 nm thick p-type Al_0.20Ga_0.75In_0.05N carrier block layer 4 is grown. When the growth of the carrier block layer 4 is completed, the supply of TMA is stopped at the same growth temperature, and the p-type Ga having a thickness of 80 nm is stopped._0.9In_0.1The growth of the light emitting device structure is completed by growing the N second cladding layer 5. When growth is complete, TMG, TMI and Cp₂After stopping the supply of Mg, it is cooled to room temperature and taken out from the MOCVD apparatus. Then p-type Ga_0.9In_0.1The transparent electrode 16 is formed on the upper surface of the second clad layer made of the N layer, the bonding electrode 17 is formed on a part of the transparent electrode 16, and the electrode 15 is formed on the lower surface of the GaN substrate, whereby the light emitting device of this embodiment is manufactured. It was.
[0042]
As described above, an extremely flat GaN substrate having a (1-101) plane 70 is manufactured using a Si substrate as a starting substrate, and then a semiconductor device is manufactured, whereby a semiconductor light emitting device having a narrow half-value width of 15 nm in the emission spectrum. was gotten. Further, the light emission intensity of the light-emitting element thus obtained was three times or more that of the element of Embodiment 1, and was extremely high in luminance.
[0043]
<Embodiment 3>
In Embodiment 1, a light-emitting element structure using a vapor phase growth method using an organic metal was manufactured on a silicon substrate inclined by 7.3 degrees from the (001) plane. Molecular beam epitaxy (MBE) It was also possible to produce it by the growth method. In the present embodiment, the MOCVD growth process of the first embodiment is changed to the following MBE growth process.
[0044]
Metals Ga, Al, and In were used as Ga, Al, and In sources, respectively. NH as a source of N_ThreeWas used.
[0045]
The cleaned silicon substrate 1 is introduced into the MBE apparatus, and cleaning is performed at a high temperature of about 1100 ° C. in a high vacuum.
[0046]
Then NH at 800 ° C_ThreeAnd Al and In are introduced and Al is about 20 nm thick._0.85In_0.15N layer 10 is grown.
[0047]
Subsequently, at the same temperature, the supply of metal Al was stopped, and metal Ga and In were introduced, respectively, and a silicon-doped Ga having a thickness of about 300 nm._0.92In_0.08N first clad layer 2 is grown.
[0048]
Thereafter, the supply of the metals Al, In, and Ga is stopped, the substrate temperature is lowered to 760 ° C., and then the light emitting layer 3 composed of multiple quantum wells (MQW) is grown.
[0049]
After the growth of the light emitting layer is completed, at the same temperature as the last barrier layer, metal Ga is introduced into the metal Al, In and Mg as the p-type doping source gas, and the p-type Al having a thickness of 50 nm_0.20Ga_0.75In_0.05N carrier block layer 4 is grown. When the growth of the carrier block layer 4 is completed, the supply of metal Al is stopped at the same growth temperature, and the p-type Ga having a thickness of 80 nm is stopped._0.9In_0.1The growth of the light emitting device structure is completed by growing the N second cladding layer 5. As described above, after the MBE method, p-type Ga_0.9In_0.1The transparent electrode 16 is formed on the upper surface of the second cladding layer made of the N layer, the bonding electrode 17 is formed on a part of the transparent electrode 16, and the electrode 15 is formed on the lower surface of the Si substrate, whereby the light emitting device of this embodiment is completed.
[0050]
<Embodiment 4>
In the first embodiment, the groove slope inclined by about 62 degrees from the silicon main face is obtained by utilizing the property that the Si (111) face is easily formed by an etching method using an etchant (wet etching). The slope obtained in this way is a so-called crystal facet, which not only has stable processing accuracy but also excellent flatness and is excellent as a base for growing a nitride semiconductor. However, the scope of application of the present invention is not limited to this. According to many experiments by the inventor, not only the silicon substrate tilted 7.3 degrees from the (001) plane is used as the main surface, but the other surfaces are also partially formed on the silicon main surface as in the first embodiment. By applying the mask 52 and further changing the etching temperature and speed, it becomes possible to form an inclined groove of 62 degrees with respect to the main surface.
[0051]
Therefore, the same result was obtained when the study was conducted using this aspect. That is, as in the first embodiment, crystal growth is possible so that the GaN (1-101) plane is substantially parallel to the substrate main surface. As a result of continuing such growth, flat GaN (1 A continuous crystal film having a −101) plane was obtained. GaN is a crystal with strong orientation, and in a normal method, it is c-axis oriented perpendicular to the main surface, and as a result, a crystal having only a C plane as the main plane can be obtained and has a plane different from the C plane. However, according to the present invention, a crystal having a GaN (1-101) plane on the surface can be easily obtained.
[0052]
<Embodiment 5>
The method for manufacturing a semiconductor device of the present invention will be described more specifically.
[0053]
As shown in FIG. 4, a mask 52 having a thickness of 100 nm made of a silicon oxide film or a silicon nitride film for facet formation is formed on a tilted silicon substrate 7.3 ° off in the [0-1-1] direction from the (001) plane. Is formed with a stripe pattern extending in the Si [01-1] direction by using a film forming technique such as a sputtering method and a photolithography technique. After that, as shown in FIG. 5, a groove having a (111) facet surface 61 on the inclined surface is formed by etching with diluted KOH aqueous solution. At this time, the shape of the groove itself has a V shape or a deformed V shape with a flat bottom region, and the other inclined surface is a (1-1-1) facet surface. Since the silicon substrate is an off-substrate, the V-shape is not bilaterally symmetric, and the (111) slope is a surface inclined about 62 ° with respect to the substrate main surface. The slope is a surface inclined about 47 °. By placing this substrate in an inclined state in the sputtering apparatus, a film is formed so that the (111) facet surface 61 does not stick to the film, and (1-1-1) silicon oxide is also formed so as to cover the facet surface. A mask 52 made of a film or a silicon nitride film is applied as shown in FIG. This is a substrate for forming a nitride semiconductor film. FIG. 8 shows the orientation relationship between the Si substrate and the facet plane at this time.
[0054]
Then, growth is performed on the Si substrate subjected to this treatment using the MOCVD method. An AlInN intermediate layer is grown on this Si off substrate, followed by growth of GaN, thereby producing a GaN substrate composed of a continuous film through the growth process as shown in FIGS. It becomes possible to do. Crystal growth starts on the (111) facet (a). The growing nitride semiconductor is oriented in the <0001> direction perpendicular to the slope. On the top surface of the grown crystal, a GaN (1-101) plane appears almost in parallel with the main surface of the substrate. Therefore, in the middle of the growth, the crystal is shaped like a triangular prism extending in the stripe direction (b). As the growth proceeds further, the diameter of the triangular prism increases, and finally the adjacent triangular prism crystals come into contact with each other (c). If the growth is further continued, the separated triangular columnar crystals are united to obtain a GaN crystal film having a flat GaN (1-101) plane on the surface (d).
[0055]
Similar results were obtained even when an AlInN intermediate layer, an AlGaN intermediate layer, or an AlGaInN intermediate layer was used as the intermediate layer used in the initial stage of growth.
[0056]
Here, the required (001) plane silicon off substrate is used, and the (111) facet plane is used as a slope inclined by 62 ° from the main surface. However, by controlling the etchant concentration and temperature of KOH, (111) Alternatively, the Si facet surface made of (211) can be formed by etching. In this case, a (211) facet plane is created by creating a stripe-shaped groove extending in the [01-1] direction on a silicon substrate off 8.6 ° in the [100] direction from the (2-1-1) plane. Can be formed as a slope inclined by 62 ° from the main surface, and a GaN crystal film having a flat surface similar to the above can also be obtained.
[0057]
This is because the nitride semiconductor crystal is grown with the vertical axis of the (211) facet plane as the c-axis, and also in this case, Si off having an angle of 62 ° with respect to the (211) plane. It is considered that a similar flat GaN substrate can be obtained by using the substrate.
[0058]
As described above, in the present invention, when the Si substrate is used, the nitride semiconductor film is likely to undergo c-axis oriented crystal growth with respect to the substrate, and a substrate having a relation between the facet and the off angle of the substrate of 62 ° is used. Thus, a crystal film having a (1-101) facet plane of a flat nitride semiconductor can be used.
[0059]
On the nitride semiconductor film formed of the continuous film thus obtained, a semiconductor light emitting device as shown in FIG. 2 is formed in the same manner as in the first embodiment, so that a high brightness semiconductor light emitting device on the Si substrate is formed. Can be made. In the semiconductor light emitting device thus obtained, the light emitting layer (active layer) has the (1-101) plane as a main surface. This is different from the conventional case where an element formed using a sapphire substrate, SiC substrate, or Si (111) substrate has (0001) as the main surface. A thin film having a main surface of nitride semiconductor (0001), which is a wurtzite structure crystal, is equivalent in band structure in a direction parallel to the main surface, but the (1-101) plane as in the present invention. In the thin film having the main surface, the direction parallel to the main surface is not equivalent in band structure. Therefore, the light-emitting element to which the present invention is applied is free from degeneration of the band in the direction parallel to the light-emitting layer (active layer). Therefore, the light-emitting element has high emission efficiency and is extremely low when applied to a semiconductor laser element. A threshold can be realized.
[0060]
<Embodiment 6>
In the fifth embodiment, a nitride semiconductor film made of a continuous film is formed through the growth process shown in FIG. 7D, and a semiconductor light emitting device is fabricated thereon. In FIG. 9, the crystal growth of each nitride semiconductor layer is completed in the growth processes (a) to (b), that is, in the state where the individual triangular prism-shaped crystals are not united, and as shown in FIG. A semiconductor light emitting element is separately formed on the triangular prism-shaped crystal body, and the light emitting element can be made to emit light individually.
[0061]
The structure of the element is as follows: n-AlGaInN intermediate layer 10, n-GaN underlayer 11, first cladding layer 2 made of n-GaInN, and In stacked on layered facets 61 formed on a Si substrate._xGa_1-xThe light emitting layer 3 is made of N, the carrier block layer 4 is made of p-AlGaInN, and the second cladding layer 5 is made of p-GaInN. Furthermore, an electrode 15 is provided on the lower surface of the silicon substrate, a transparent electrode 16 is provided on the upper surface of the second cladding layer 5, and a bonding electrode 17 is provided on a part of the upper surface of the transparent electrode 16.
[0062]
<Embodiment 7>
In the description of the first to fourth embodiments, it has been described that the nitride semiconductor is grown only on one slope of the stripe groove provided in the Si substrate. However, in this embodiment, the slopes on both sides are separated from the main surface. As shown in FIG. 10, each semiconductor light emitting element was formed on the Si slopes on both sides in the same manner as described in the sixth embodiment.
[0063]
In the above embodiment, the semiconductor light emitting element which is an LED is mainly described as the semiconductor element. However, the scope of the present invention is not limited to this and may be applied to a semiconductor laser element. Using the above technique, a GaN-based MESFET (Metal semiconductor Field effect) in which an electrode composed of a source, a drain and a gate is fabricated on a film obtained by growing a Si-doped GaN layer through a high resistance layer composed of an AlGaN layer. transistor), and further to a GaN-based MODFET (Modulation Dope Field Effect Transistor) in which Si is doped on the GaN channel layer. In these, the flatness of each layer can be improved. The mobility of electrons traveling in the channel layer due to uneven scattering is improved, and the cutoff frequency is As a result, a semiconductor device with good electrical characteristics can be obtained, and the conductivity between the Si substrate and the nitride semiconductor layer can be ensured. Thus, it is possible to manufacture the semiconductor element circuit.
[0064]
Although the embodiment of the present invention has been described above, the embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and includes meanings equivalent to the terms of the claims and all modifications within the scope.
[0065]
【The invention's effect】
The present invention relates to a nitride semiconductor device fabricated on a silicon substrate, and a surface inclined by 62 degrees from the main surface of the silicon substrate, the silicon substrate (001) plane being 7.3 degrees around the [01-1] axis. By using a rotated surface or a surface tilted within 3 degrees in any direction from these surfaces, it becomes possible to obtain a very flat high-quality crystal film having a (1-101) epitaxial surface. By using the epitaxial surface, it has become possible to provide a semiconductor element having a sharp interface and excellent photoelectric characteristics.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram for forming a (1-101) facet surface of a nitride semiconductor film.
FIG. 2 is a cross-sectional view illustrating a light-emitting element according to an embodiment of the present invention.
FIG. 3 is a diagram showing a relationship of a substrate nitride semiconductor film used in the present invention.
FIG. 4 is a view for explaining the method for producing a compound semiconductor of the present invention.
FIG. 5 is a drawing for explaining the method for producing a compound semiconductor of the present invention.
FIG. 6 is a drawing for explaining the method for producing a compound semiconductor of the present invention.
FIG. 7 is a drawing for explaining the method for producing a compound semiconductor of the present invention.
FIG. 8 is a diagram for explaining the crystal orientation relationship in the Si substrate of the fifth embodiment.
FIG. 9 is a cross-sectional view showing a semiconductor light emitting element of a sixth embodiment.
FIG. 10 is a cross-sectional view showing a semiconductor light emitting element according to a seventh embodiment.
[Explanation of symbols]
1 Si (001) off-substrate, 2 1st cladding layer made of n-GaInN, 3 Non-doped InGaN light emitting layer, 4 p-AlGaIn carrier block layer, 5 Second cladding layer made of p-GaInN, 10 n-AlGaInN Layer, 11 GaN underlayer, 15 electrode, 16 transparent electrode, 17 bonding electrode, 52 mask (silicon oxide film or silicon nitride film), 53 nitride semiconductor crystal, 60 silicon (001) plane, 61 silicon (111) ) Facet plane, 70 (1-1101) facet plane of nitride semiconductor, 71 (0001) facet plane of nitride semiconductor, 72 (1-101) plane of nitride semiconductor in a continuous film state, 80 nitride C-axis of semiconductor, 81 Growth direction of nitride semiconductor.

Claims (9)

A silicon substrate and a general formula In _x Ga _y Al _z N (where x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) formed on the main surface of the silicon substrate. A silicon semiconductor substrate having a surface inclined by 62 degrees from the main surface of the silicon substrate, or in a range within 3 degrees in any direction from the surface. A groove having an inclined surface as an inclined surface, the compound semiconductor layer is formed on the inclined surface, an axis perpendicular to the inclined surface is a c-axis of the compound semiconductor layer, and a growth surface of the compound semiconductor layer is (1-101) semiconductor device characterized facet der Rukoto. In a semiconductor element having a compound semiconductor layer represented by the general formula In _x Ga _y Al _z N (where x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1), the compound semiconductor A principal surface composed of a layer rotated by 7.3 degrees around the (01-1) axis about the (100) plane, or a plane within a range tilted within 3 degrees in any direction from this plane. The silicon substrate includes a groove having a (111) plane as an inclined surface, the compound semiconductor layer is formed on the inclined surface, and an axis perpendicular to the inclined surface is the compound semiconductor. a c-axis of the layer, the growth surface of the compound semiconductor layer is a semiconductor device characterized (1-101) facet der Rukoto.   The semiconductor element according to claim 1, wherein a <0001> direction of the compound semiconductor layer is substantially perpendicular to the inclined surface. The semiconductor element is a semiconductor light emitting element having a light emitting layer,
The compound semiconductor layer includes the light emitting layer,
The semiconductor device according to claim 1 , wherein the light emitting layer has a (1-101) plane as a growth plane. Forming a groove having, on the main surface of the silicon substrate, a surface inclined by 62 degrees from the main surface, or a surface inclined within a range of 3 degrees or less in any direction from the surface;
Forming a compound semiconductor layer represented by the general formula In _x Ga _y Al _z N (x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) on the slope; equipped with a,
Crystal growth of the compound semiconductor layer proceeds with an axis perpendicular to the slope as a c-axis of the compound semiconductor film, and a (1-101) facet plane of the compound semiconductor layer is formed as a plane. Device manufacturing method. A silicon substrate having a principal surface constituted by a surface rotated by 7.3 degrees around the [01-1] axis or a surface within a range tilted within 3 degrees in any direction from this surface. Forming a groove having a (111) plane as a slope in the main surface;
Forming a compound semiconductor layer represented by the general formula Al _x Ga _y In _z N (where x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) on the slope; With
Crystal growth of the compound semiconductor layer proceeds with an axis perpendicular to the slope as a c-axis of the compound semiconductor film, and a (1-101) facet plane of the compound semiconductor layer is formed as a plane. Device manufacturing method. The said groove | channel is provided with two or more on Si substrate, The said compound semiconductor layer formed from on the slope of each said groove | channel is united according to crystal growth, The Claim 5 or Claim 6 characterized by the above-mentioned. A method for manufacturing a semiconductor device. The method for manufacturing a semiconductor device according to claim 7 , further comprising a step of removing the silicon substrate after forming the compound semiconductor layer. Forming a plurality of grooves on the main surface of the silicon substrate, each having a surface inclined by 62 degrees from the main surface, or a surface inclined within a range of 3 degrees in any direction from the surface;
Forming a compound semiconductor crystal represented by the general formula In _x Ga _y Al _z N (x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) on the slope; ,
The step of obtaining a continuous film-like compound semiconductor crystal by further growing and uniting the compound semiconductor crystal formed from the slope of each groove,
After obtaining the film-like compound semiconductor crystal, removing the silicon substrate, obtaining a semiconductor substrate made of the compound semiconductor crystal ,
The growth of the compound semiconductor crystal proceeds with the axis perpendicular to the slope as the c-axis of the compound semiconductor crystal, and the (1-101) facet plane of the compound semiconductor crystal is formed as a plane. Manufacturing method.

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