JP2001111175A - Substrate for semiconductor device and method of fabrication thereof and semiconductor device using that substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fabricate a flat substrate for a semiconductor device in which defects are suppressed through a simple process. SOLUTION: A GaN buffer layer 12 and a GaN layer 13 are grown on a sapphire substrate 11 at 500 deg.C and 1050 deg.C, respectively, and a line and space pattern is formed using normal lithography and dry etching and then a GaN layer 16 is grown selectively. Subsequently, an SiO2 film 17 is formed and then removed by 3 μm above the center of a space obtained by removing the buffer layer 12 and the GaN layer 13 and a GaN layer 18 is grown selectively thereon. Thereafter, an SiO2 film 19 is formed and then removed above the center of a space in the SiO2 film 17 and a GaN layer 20 is grown selectively thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device substrate and a method of manufacturing the same, and a semiconductor device using the semiconductor device substrate, in particular, a semiconductor device substrate made of a group III nitrogen compound, a method of manufacturing the same, and a semiconductor thereof. The present invention relates to a semiconductor device and a semiconductor laser device using a device substrate.

[0002]

2. Description of the Related Art As a short-wavelength semiconductor laser of 410 nm band, Jpn. Appl. Phys. Vol. 38.pp. L226-L229 published in 1999.
After forming GaN on the sapphire substrate,
After forming GaN using selective growth using iO ₂ as a mask, the sapphire substrate is peeled off on the GaN substrate,
n-GaN buffer layer, n-InGaN crack preventing layer, AlGaN / n-GaN modulation-doped superlattice cladding layer, n-GaN optical waveguide layer, undoped InGaN / n-
InGaN multiple quantum well active layer, p-AlGaN carrier block layer, p-GaN optical waveguide layer, AlGaN / p-
A structure in which a GaN modulation-doped superlattice cladding layer and a p-GaN contact layer are stacked has been reported. However, with this semiconductor laser, the defect density is still high, and reliability at high output has not been obtained.

Also, Ext. Abstr. (MRS Fall Meet. Boston,
1998) G3.38, Pendeo-Ep by TSZheleva et al.
itaxy-A New Approach for Lateral Growth of Gallium
Nitride Structures is introduced. Here, S
After forming GaN without using iO ₂ as a mask, the GaN is stripped off to the sapphire substrate, and GaN is grown on the substrate. Is reported to be formed.

[0004] In addition, utilizing the above method, 1999
In SPIE Vol.3628.pp.158, it is reported that an InGaN multiple quantum well semiconductor laser can be formed. However, the reliability is limited to a level of 5 mW, and it is necessary to further reduce the defect density.

In Japanese Patent Application Laid-Open No. 10-312971, Ga
As a method of suppressing cracks caused by the difference in thermal expansion and lattice constant between the N compound semiconductor layer and the sapphire substrate crystal and suppressing the introduction of defects, a growth region is limited by a mask, and a facet structure of a GaN compound semiconductor film is formed by epitaxial growth. Then, a crystal growth method has been reported in which the facet structure is completely buried until the mask is covered, and finally a flat surface is obtained. In this method, since the entire base of the seed growth region is grown on a substrate with a large lattice mismatch, the crystal orientation that grows in the lateral direction changes due to the influence of the substrate, and planarization is also difficult, Even if this method is repeated, there is a difference in the plane orientation, so that the defect cannot be reduced to a practical level.

[0006]

As described above, the short-wavelength semiconductor laser device has a problem in reliability and the like under a high output because the substrate has many crystal defects.

In view of the above circumstances, the present invention provides a semiconductor device substrate having high reliability and a low defect density even under high output oscillation, a method of manufacturing the same, a semiconductor device and a semiconductor laser using the semiconductor device substrate. It is intended to provide a device.

[0008]

According to a method of manufacturing a substrate for a semiconductor device of the present invention, a first group III nitrogen compound is formed on a base substrate via a buffer layer of AlN or GaN formed by a low-temperature growth method. A first step of forming a layer;
The crystal layer comprising the buffer layer and the first group III nitrogen compound layer is removed in a stripe form, up to the top surface of the base substrate or a part of the base substrate, and a line portion in which the crystal layer is left in a line is formed. A line-and-space pattern consisting of a space portion formed between the line portions is formed, and a second group III nitrogen compound layer is formed thereon, and the line portion is used as a growth nucleus of a crystal of the group III nitrogen compound. A second step of forming until the line and space pattern disappears, and at least a line width at a position corresponding to the line portion on the second group III nitrogen compound layer, the group III nitrogen compound may be crystal-grown. Forming a line-and-space pattern comprising a line portion of the mask layer and a space portion formed between the line portions, wherein the mask layer is A third group III nitrogen compound layer is formed until the mask layer is covered by using the surface of the second group III nitrogen compound layer that is not formed as a growth nucleus of a crystal of the group III nitrogen compound. It is characterized by including a step.

After the third step, at least a portion corresponding to the space portion of the mask layer below the group III nitrogen compound layer on the group III nitrogen compound layer formed in the immediately preceding step is provided. At the width of the space portion, a mask layer made of a material in which the group III nitrogen compound cannot grow crystals is formed, and the surface of the group III nitrogen compound layer where the mask layer is not formed is grown on the surface of the group III nitrogen compound crystal. As a nucleus, a step of forming a group III nitrogen compound layer until the mask layer is covered may be performed at least once.

[0010] The group III nitrogen compound layer may be formed while doping impurities.

After the last of the above steps, the base substrate may be removed.

The base substrate is made of sapphire, Si
C, ZnO, LiGaO ₂ , LiAlO ₂ , ZnSe, G
Desirably, it is any one selected from the group consisting of aAs, GaP, Ge, and Si.

It is preferable that the buffer layer and the group III nitrogen compound layer are formed by HVPE, MOCVD or MBE.

The group III nitrogen compound layer is made of GaN, In,
Desirably, it is made of one selected from the group consisting of GaN, AlGaN, InAlGaN, InAlN, and InN.

The substrate for a semiconductor element of the present invention is characterized by being manufactured by the method for manufacturing a substrate for a semiconductor element having the above structure.

A semiconductor device according to the present invention is characterized in that a semiconductor layer is provided on a semiconductor device substrate manufactured by the method for manufacturing a semiconductor device substrate having the above structure.

A semiconductor laser device according to the present invention comprises a semiconductor layer on a semiconductor element substrate manufactured by the method for manufacturing a semiconductor element substrate according to the above structure, and a current injection window formed on the semiconductor layer. Stripe width is 10μ
m or more.

[0018]

According to the conventional method for manufacturing a substrate for a semiconductor device, a group III nitrogen compound is grown directly on a base substrate. However, since the lattice constant difference between the base substrate and the group III nitrogen compound is large, the group III nitrogen compound is grown. Penetration defects occurred in the compound layer. Then, the penetrating defect is partially formed in SiO 2
After suppression by a mask such as a _two- layer film, selective growth of a group III nitrogen compound crystal was performed.
Since there is a penetrating defect in the group-III nitrogen compound layer, the penetrating defect grows from a portion where the mask layer is not formed,
There was a limit to reducing the defect density to a practical level. However, according to the method for manufacturing a semiconductor element substrate of the present invention, after growing a first group III nitrogen compound layer on a base substrate via a buffer layer by a low-temperature growth method, a buffer layer having many defects is formed. The first group III nitrogen compound layer is partially removed so as to form a line-and-space pattern, and a new group III nitrogen compound crystal is selectively grown thereon by utilizing the lateral growth of the crystal. Therefore, penetrating defects exist from the line portion to the upper portion of the line portion, but the group III nitrogen compound layer between the newly crystallized line portions has few defects.

In the method of manufacturing a substrate for a semiconductor device according to the present invention, a mask layer is further formed on a line portion of a crystal layer comprising a buffer layer having a penetrating defect and a first group III nitrogen compound layer. Since it is formed, growth of a penetrating defect in an upper layer can be suppressed. Further, since the group III nitrogen compound is selectively grown using the first group III nitrogen compound layer between the mask layers as a nucleus for crystal growth, a flat group III nitrogen compound layer without defects can be obtained.

Further, a mask layer is further formed on the group III nitrogen compound layer formed in the previous step at a position corresponding to the space portion of the lower mask layer, and at a position where the mask layer is not formed. By repeating the step of selectively growing a group III nitrogen compound using the exposed group III nitrogen compound layer as a crystal growth nucleus, defects can be reduced in each step, and ultimately completely free of defects A substrate can be obtained.

Further, a conductive substrate can be manufactured by doping an impurity when crystal growing the group III nitrogen compound layer.

Further, by removing the base substrate after the crystal growth of the group III nitrogen compound layer, electrical conduction can be easily obtained from the back surface of the substrate without going through a complicated process.

Further, according to the semiconductor device of the present invention, since the semiconductor device is formed on a substrate having no defect, a highly reliable semiconductor device can be obtained.

A semiconductor device is manufactured using the semiconductor device substrate manufactured by the method of manufacturing a semiconductor device substrate of the present invention.
For example, a semiconductor light emitting element, a field effect transistor, a semiconductor laser device, a semiconductor optical amplifier, a photodetector, and the like can be manufactured.

In particular, by using a semiconductor device substrate manufactured as described above for a semiconductor laser device having a stripe width of 10 μm or more, a highly reliable laser can be obtained even at a high output.

Therefore, the semiconductor device as described above can be used in the fields of high-speed information / image processing, communication, measurement, medical treatment, and printing.

[0027]

Embodiments of the present invention will be described below in detail with reference to the drawings.

A method of manufacturing a substrate for a semiconductor device according to the first embodiment of the present invention will be described. FIG. 1 shows a process of manufacturing the substrate for a semiconductor device.

As shown in FIG. 1a, trimethylgallium (TMG) and ammonia are used as growth materials, silane gas is used as an n-type dopant gas, and cyclopentadienylmagnesium is used as a p-type dopant by metalorganic vapor phase epitaxy. Using (Cp ₂ Mg), a GaN buffer layer 12 having a thickness of about 20 nm is formed on a (0001) C-plane sapphire substrate 11 at a temperature of 500 ° C. Subsequently, the temperature is set to 1050 ° C., and the GaN layer 13 is grown to about 2 μm.
After forming a SiO ₂ film 14 thereon and applying a resist 15 thereon, using normal lithography,

[0030]

(Equation 1)

By removing the SiO ₂ film 14 having a width of 5 μm in the direction and forming a line portion of the SiO ₂ film 14 having a width of about 5 μm, a line and space pattern having a period of about 10 μm is formed.

Next, as shown in FIG. 1B, using the resist 15 and the SiO ₂ film 14 as a mask, the buffer layer 12 and the GaN layer 13 are removed to the upper surface of the sapphire substrate 11 by dry etching using a chlorine-based gas. , Resist 15 and SiO
_{2 The} film 14 is removed. At this time, the sapphire substrate 11 may be etched.

Next, as shown in FIG. 1C, the GaN layer 16 is selectively grown to about 20 μm. At this time, the space portion is finally filled by the lateral growth, and the surface is flattened. At this point, threading dislocations have occurred in the upper portion of the line portion of the layer including the buffer layer 12 and the GaN layer 13, but no threading dislocation has occurred in the GaN layer 16 between the line portions.

[0034] Next, as shown in FIG. 1d, SiO ₂ film 17
Formed at the center of the space between the line portions where the buffer layer 12 and the GaN layer 13 remain.
_{2 The} film 17 is removed by about 3 μm.

Next, as shown in FIG.
At 050 ° C., the GaN layer 18 is selectively grown to about 20 μm. At this time, the space portion is finally filled by the lateral growth, and the surface is flattened.

Next, as shown in FIG. 1f, SiO ₂ film 19
Is formed, and S located above the remaining portion of the SiO ₂ film 17 is formed.
The iO ₂ film 19 is removed by about 3 μm in width, and the GaN layer 20 is selectively grown thereon by setting the growth temperature to 1050 ° C. to about 20 μm. At this time, the lateral growth eventually fills the space and flattens the surface, completing the GaN substrate.

On the GaN substrate manufactured as described above,
GaN-based semiconductor layer, for example, GaN, InGaN, AlG
By growing crystals of aN, InGaAlN, etc.,
Semiconductor light emitting elements and electronic devices can be manufactured.

On the GaN substrate manufactured as described above, a GaN layer is grown to a thickness of about 100 to 200 μm, and after removing the sapphire substrate, a GaN-based semiconductor layer such as GaN, InGaN, AlGaN, In
By growing crystals of GaAlN or the like, a semiconductor light emitting element and an electronic device can be manufactured.

In the present embodiment, the case of undoping without doping impurities when growing a crystal of the GaN layer has been described.
An n-type or p-type GaN conductive substrate can be manufactured. For example, in the case of doping Mg as a p-type impurity, a heat treatment is performed in a nitrogen atmosphere after growth or a growth is performed in a nitrogen-rich atmosphere for activation. Is also good.

As a method of growing a crystal, Ga which is a reaction product of gallium (Ga) and hydrogen chloride (HCl) is used.
Hydride VP using Cl and ammonia (NH ₃ )
The E method may be used.

A method for manufacturing a semiconductor device substrate according to a second embodiment of the present invention will be described. FIG. 2 shows a process for manufacturing the semiconductor device substrate.

As shown in FIG. 2A, trimethylgallium (TM)
G) and ammonia, and as an n-type dopant gas,
Silane gas is used, and cyclopentadienyl magnesium (Cp ₂ Mg) is used as a p-type dopant. (0
001) A at a temperature of 500 ° C. on a 6H-SiC substrate 31
The 1N buffer layer 32 is formed with a thickness of about 20 nm. Subsequently, the temperature is set to 1050 ° C., and the GaN layer 33 is grown to about 2 μm. Thereafter, an SiO ₂ film 34 is formed, and a resist 3
After applying 5, using normal lithography,

[0043]

(Equation 1)

By removing the SiO ₂ film 34 having a width of 5 μm in the direction and forming a line portion of the SiO ₂ film 34 having a width of about 5 μm, a line and space pattern having a period of about 10 μm is formed.

Next, as shown in FIG. 2B, using the resist 35 and the SiO ₂ film 34 as a mask, the buffer layer 32 and the GaN layer 33 are dry-etched using a chlorine-based gas.
The resist 35 and the SiO ₂ film 34 are removed up to the upper surface of the C substrate 31. At this time, the SiC substrate 31 may be etched.

Next, as shown in FIG. 2C, a GaN layer 36 is selectively grown to a thickness of about 20 μm. At this time, the space portion is finally filled by the lateral growth, and the surface is flattened. At this point, threading dislocations have occurred in the upper portion of the line portion of the layer including the buffer layer 32 and the GaN layer 33, but no threading dislocation has occurred in the GaN layer 36 between the line portions.

Next, as shown in FIG. 2D, an SiO ₂ film 37 is formed on the GaN layer 36, and the buffer layer 32 and the GaN
The SiO ₂ film 37 existing at an intermediate position of the space between the lines where the layer 33 remains is removed by about 3 μm.

Next, as shown in FIG.
At 050 ° C., the GaN layer 38 is selectively grown to about 20 μm. At this time, the space portion is finally filled by the lateral growth, and the surface is flattened.

Next, as shown in FIG. 2f, the SiO ₂ film 39 is formed on the GaN layer 38, the SiO ₂ film 39 is removed width of approximately 3μm that is located above the remainder of the SiO ₂ film 37, On top of that, the growth temperature is set to 1050 ° C.
Selectively grow by about μm. At this time, the lateral growth eventually fills the space and flattens the surface,
The GaN substrate is completed.

Also in the present embodiment, a GaN-based semiconductor layer (GaN,
By growing InGaN, AlGaN, InGaAlN, etc.), a semiconductor light emitting element and an electronic device can be manufactured.

Alternatively, a GaN layer is grown to a thickness of about 100 to 200 μm on the GaN substrate manufactured as described above, and a GaN-based semiconductor layer is formed on the GaN substrate from which the base substrate SiC substrate has been removed by polishing or chemical etching. (G
aN, InGaN, AlGaN, InGaAlN, etc.) can also be used to produce a semiconductor light emitting device and an electronic device.

The base substrate is a (0001) plane 4H-Si
A C substrate may be used.

In the present embodiment, the case of undoping without doping impurities when selectively growing the GaN layer has been described.
Type GaN conductive substrate can be manufactured. For example,
When doping Mg as a p-type impurity, either a heat treatment is performed in a nitrogen atmosphere after growth or a growth is performed in a nitrogen-rich atmosphere to activate Mg. It is desirable. By manufacturing a conductive substrate by doping impurities, an electrode can be formed on the back surface side of the substrate.

The GaN layer can be grown by a hydride VPE method using GaCl, which is a reaction product of gallium (Ga) and hydrogen chloride (HCl), and ammonia (NH ₃ ), or a molecular beam using a gas source. An epitaxial growth method may be used.

In the above two embodiments, the case where the sapphire substrate and the SiC substrate are used as the base substrate has been described.
O, LiGaO ₂ , LiAlO ₂ , ZnSe, GaAs,
GaP, Ge, Si or the like can be used. Further, by removing the base substrate after the last step, electrical conduction can be obtained from the back surface.

As the mask material, the above SiO ₂
In addition to the film, a mask material having good heat resistance to high temperatures, such as SiN, AlN, and TiN, may be used.

In the above two embodiments,
Although the creation of the GaN substrate has been described, AlGaN, InGaN, InAlGaN, InAl
These substrates may be created by growing N, InN, or the like.

Next, a description will be given of a semiconductor laser device according to a third embodiment of the present invention. FIG. 3 is a sectional view of the semiconductor laser device.

According to the first embodiment, an n-type GaN substrate is formed by selectively growing GaN on a sapphire substrate to produce a GaN substrate, and then peeling off the sapphire substrate.
Using 71, n-GaN buffer layer 72, 150 pairs of n
-Al _0.14 Ga _0.86 N (2.5 nm) / GaN (2.5
nm) Superlattice cladding layer 73, n-GaN optical waveguide layer 74, n
-In _0.02 Ga _0.98 N (10.5 nm) / n-In _0.15
Ga _0.85 N (3.5 nm) triple quantum well active layer 75, p-
Al _0.2 Ga _0.8 N carrier blocking layer 76, p-GaN optical waveguide layer 77, 150 pairs of p-Al _0.14 Ga _0.86 N (2.
5 nm) / GaN (2.5 nm) superlattice cladding layer 78,
A p-GaN contact layer 79 is laminated. Here, Mg is used as the p-type impurity. For the activation of Mg, either a method of performing heat treatment in a nitrogen atmosphere after growth or a method of performing growth in a nitrogen-rich atmosphere may be used.

Next, an SiO ₂ film 80 (not shown) is formed, and the SiO ₂ film 80 outside the stripe region having a width of 2 μm is removed by ordinary lithography. By selective etching with RIE (reactive ion etching equipment), p
Etching is performed halfway of the mold superlattice cladding layer 78. The remaining thickness of the cladding layer in this etching is a thickness that can achieve the fundamental transverse mode oscillation. Thereafter, the SiO ₂ film 80 is removed, a SiO ₂ film 81 is subsequently formed, and the S
The iO ₂ film 81 is removed, and a p-electrode 82 of Ni / Au is formed. Next, the substrate is polished and n / Ti
An electrode 83 is formed, a high-reflection coat and a low-reflection coat are applied to the cavity surface formed by cleavage, and then the chip is formed.
Complete the semiconductor laser device.

The wavelength band λ in which the semiconductor laser device oscillates
As for the active layer, In _x4 Ga _1-x4 N is used as an active layer, and the composition is set to 0.
By setting ≦ X4 ≦ 0.5, 360 ≦ λ ≦ 550 (n
Control up to the range of m) is possible.

The semiconductor layer according to the present embodiment may be formed by inverting the conductivity (switching between n-type and p-type).

In this embodiment, the semiconductor laser device which oscillates in a fundamental mode with a narrow stripe has been described. However, the substrate for a semiconductor device of the present invention is also applicable to the manufacture of a semiconductor laser device having a wide stripe of 10 μm or more. be able to.

Further, using the semiconductor element substrate according to the present invention, semiconductor elements such as a field effect transistor, a semiconductor laser, a semiconductor optical amplifier, a semiconductor light emitting element, and a photodetector can be formed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a method for manufacturing a semiconductor device substrate according to a first embodiment of the present invention;

FIG. 2 is a view showing a method for manufacturing a semiconductor element substrate according to a second embodiment of the present invention;

FIG. 3 is a sectional view showing a semiconductor laser device according to a third embodiment of the present invention;

[Explanation of symbols]

11 Sapphire substrate 12 GaN buffer layer 13,33 GaN layer 14,17,19,34,37,39 SiO ₂ film 15,35 Resist 16,18,20,36,38,40 GaN layer 31 SiC substrate 32 AlN buffer layer 71 GaN substrate from which base substrate has been removed 72 n-GaN buffer layer 73 n-AlGaN / GaN superlattice cladding layer 74 n-GaN optical waveguide layer 75 n-InGaN / InGaN triple quantum well active layer 76 p-AlGaN carrier block layer 77 p-GaN optical waveguide layer 78 p-AlGaN / GaN superlattice cladding layer 79 p-GaN contact layer 81 SiO ₂ film 82 p electrode 83 n electrode

Claims (10)

[Claims] A first step of forming a first group III nitrogen compound layer on a base substrate via a buffer layer of AlN or GaN formed by a low-temperature growth method; A crystal layer composed of one group III nitrogen compound layer is removed in a stripe shape, up to the upper surface of the base substrate, or to a part of the base substrate, and a line portion and a line portion in which the crystal layer is left in a line shape Forming a line-and-space pattern consisting of a space part formed between the parts, a second group III nitrogen compound layer thereon, and the line part as a growth nucleus of a crystal of the group III nitrogen compound, A second step of forming until the line and space pattern disappears, and a group corresponding to the line portion on the second group III nitrogen compound layer, at least the line width, group III Forming a mask layer made of a material in which the nitrogen compound cannot grow crystals, forming a line-and-space pattern including a line portion of the mask layer and a space portion formed between the line portions; Forming a third group III nitrogen compound layer until the mask layer is covered with the surface of the second group III nitrogen compound layer where no is formed as a growth nucleus of a crystal of the group III nitrogen compound. A method for manufacturing a substrate for a semiconductor device, comprising the steps of: 2. After the third step, a portion above the group III nitrogen compound layer formed in the immediately preceding step and corresponding to a space portion of a mask layer below the group III nitrogen compound layer. Forming a mask layer made of a material in which the group III nitrogen compound cannot grow crystals at least in the width of the space portion, and forming a surface of the group III nitrogen compound layer on which the mask layer is not formed with a crystal of the group III nitrogen compound. 2. The method according to claim 1, wherein the step of forming a group III nitrogen compound layer as a growth nucleus is performed at least once until the mask layer is covered. 3. The method according to claim 1, wherein the group III nitrogen compound layer is formed while doping impurities. 4. The method according to claim 1, wherein the base substrate is removed after the last of the steps. 5. The method according to claim 1, wherein the base substrate is sapphire, Si
C, ZnO, LiGaO ₂ , LiAlO ₂ , ZnSe, G
3. The method according to claim 1, wherein the material is any one selected from the group consisting of aAs, GaP, Ge, and Si.
5. The method for manufacturing a semiconductor element substrate according to 3 or 4. 6. The method according to claim 1, wherein the buffer layer and the group III nitrogen compound layer are formed by HVPE, MOCVD or MBE. Method. 7. The method according to claim 1, wherein the group III nitrogen compound layer comprises GaN, I
The method for manufacturing a substrate for a semiconductor device according to claim 1, wherein the method comprises one selected from the group consisting of nGaN, AlGaN, InAlGaN, InAlN, and InN. 8. A substrate for a semiconductor element manufactured by the method for manufacturing a substrate for a semiconductor element according to claim 1. 9. A semiconductor device comprising a semiconductor layer on a semiconductor device substrate manufactured by the method for manufacturing a semiconductor device substrate according to claim 1. Description: 10. A semiconductor element substrate provided on a semiconductor element substrate manufactured by the method for manufacturing a semiconductor element substrate according to any one of claims 1 to 8, and a current formed on the semiconductor layer. The width of the stripe serving as the injection window is 10 μm
A semiconductor laser device characterized by the above.