JP2000077336A - Substrate for semiconductor growth, manufacture thereof, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a substrate for semiconductor growth which is made of family-III-V nitride-based semiconductor in its major surface, in which a growth layer can be made thin, a shape of a mask edge portion can have no influence on a defect propagation direction of the growth layer, and a probability of gap generation between the growth layer and an inorganic mask can be made very low when traversal epitaxial growth is carried out on the substrate with use of the mask, a method for manufacturing the substrate, and a semiconductor device using the substrate. SOLUTION: A GaN layer 2 is grown on a sapphire substrate 1, an inorganic mask 3 is formed on the GaN layer so that a surface of the GaN layer becomes substantially flat, thereby obtaining a semiconductor growth substrate. The inorganic mask 3 is formed by implanting Si and O or N ions into the GaN layer 2 and then heating it, by implanting Si ions into the GaN layer 2 and then heating it in an atmosphere containing O or N ions, or by selectively forming an Si film on the GaN layer and then oxidizing or nitrifying the Si film. The GaN layer is transversely epitaxially grown on the substrate 1, an element layer is grown on the GaN layer, at which stage a semiconductor device such as a GaN-based semiconductor laser is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor growth substrate, a method of manufacturing the same, and a semiconductor device.
It is suitably applied to a semiconductor laser, a light emitting diode, an electron transit element, or the like using a nitride III-V compound semiconductor.

[0002]

2. Description of the Related Art In epitaxial growth of a semiconductor layer, in order to reduce the defect density in the semiconductor layer, an epitaxial lateral overgrowth (Epitaxial Lateral Overgrowth,
A growth technique called an ELO method is known (for example, J. Jpn. Appl. Phys., Vol. 28, no. 3, pp. L337-339, 198).
9), Attempts have been made to apply it to the growth of GaN (for example, the Japan Society for the Promotion of Science, short-wavelength optical device 162th committee, 7th meeting and photoelectric interconversion 125th committee, 160th meeting)
Of the Joint Study Group (September 26, 1997), p.
p. 18-24). In this lateral epitaxial growth method, in order to reduce the defect density of a semiconductor layer to be grown, an inorganic mask made of a SiO ₂ film or the like is formed on a substrate, and then the semiconductor layer is grown thereon.

Conventionally, the formation of an inorganic mask used in this lateral epitaxial growth method has been performed as follows. That is, first, for example, a SiO ₂ film is formed on a substrate by a chemical vapor deposition (CVD) method. The thickness of this SiO ₂ film is usually 0.1 μm or more. Next, a resist pattern having a predetermined shape is formed on the SiO ₂ film by photolithography. Next, using the resist pattern as a mask, the SiO ₂ film is etched by a dry etching method or a wet etching method, and then the resist pattern is removed. Thereby, an inorganic mask is formed.

[0004]

However, as an inorganic mask for reducing the defect density of the semiconductor layer, SiO _{2 is used.}
In the above-described conventional lateral epitaxial growth method using a film, the semiconductor layer must be grown at least by the thickness of the SiO ₂ film. It is disadvantageous if it is late.

In addition, since the etching shape (particularly, angle) of the edge portion of the inorganic mask made of the SiO ₂ film affects the propagation direction of defects in the semiconductor layer grown by the lateral epitaxial growth method, strict control is required. This needs to be done, but this is very difficult in practice.

Further, since the SiO ₂ film constituting the inorganic mask is formed on the substrate by the CVD method,
On the substrate surface, there is a step having a height corresponding to the thickness of the SiO ₂ film. For this reason, when performing lateral epitaxial growth on the substrate, voids may be generated between the semiconductor layer to be grown and the inorganic mask, which is not preferable.

Therefore, an object of the present invention is to reduce the thickness of a growth layer when performing lateral epitaxial growth on a substrate having at least one principal surface made of a nitride III-V compound semiconductor using an inorganic mask. A semiconductor growth substrate having no problem that the shape of the edge portion of the inorganic mask affects the direction of propagation of defects in the growth layer, and in which there is very little possibility that a void is formed between the growth layer and the inorganic mask. And a method of manufacturing the same, and a semiconductor device using the semiconductor growth substrate.

[0008]

In order to achieve the above object, a first aspect of the present invention is directed to a first aspect of the present invention, wherein at least one major surface is formed on one major surface of a substrate made of a nitride III-V compound semiconductor. An inorganic mask as a mask for directional epitaxial growth is provided with one main surface provided substantially in a flat state.

In a second aspect of the present invention, silicon and oxygen are selectively introduced into one main surface of a substrate having at least one main surface made of a nitride III-V compound semiconductor, and then the substrate is heated. A method for manufacturing a semiconductor growth substrate, characterized in that silicon oxide is selectively formed on one main surface by reacting silicon and oxygen.

According to a third aspect of the present invention, after selectively introducing silicon into one main surface of a substrate having at least one main surface made of a nitride III-V compound semiconductor, the substrate is placed in an atmosphere containing at least oxygen. A method for manufacturing a substrate for semiconductor growth, characterized in that silicon oxide is selectively formed on one principal surface of a substrate by heating the inside to react silicon and oxygen.

According to a fourth aspect of the present invention, silicon is selectively introduced into one principal surface of a substrate having at least one principal surface made of a nitride III-V compound semiconductor, and then the substrate is subjected to oxygen plasma treatment. A method for manufacturing a semiconductor growth substrate, characterized in that silicon oxide is selectively formed on one main surface of a substrate by reacting silicon and oxygen.

According to a fifth aspect of the present invention, silicon and nitrogen are selectively introduced into one main surface of a substrate having at least one main surface made of a nitride III-V compound semiconductor, and then the substrate is heated. A method for manufacturing a semiconductor growth substrate, characterized in that silicon nitride is selectively formed on one main surface of a substrate by reacting silicon and nitrogen.

According to a sixth aspect of the present invention, after selectively introducing silicon into one main surface of a substrate having at least one main surface made of a nitride III-V compound semiconductor, the substrate is placed in an atmosphere containing at least nitrogen. A method for manufacturing a substrate for semiconductor growth, characterized in that silicon nitride is selectively formed on one main surface of a substrate by heating the inside to react silicon and nitrogen.

According to a seventh aspect of the present invention, silicon is selectively introduced into one main surface of a substrate having at least one main surface made of a nitride III-V compound semiconductor, and then the substrate is subjected to a nitrogen plasma treatment. A method for manufacturing a semiconductor growth substrate, characterized in that silicon nitride is selectively formed on one main surface of a substrate by reacting silicon and nitrogen.

According to an eighth aspect of the present invention, a silicon film is selectively formed on one principal surface of a substrate having at least one principal surface made of a nitride III-V compound semiconductor, and then the substrate is exposed to at least oxygen. Wherein the silicon oxide film is selectively formed on one main surface of the substrate by heating in an atmosphere containing silicon to react silicon and oxygen in the silicon film. is there.

According to a ninth aspect of the present invention, a silicon film is selectively formed on one main surface of at least one main surface made of a nitride III-V compound semiconductor, and then the substrate is subjected to oxygen plasma treatment. And reacting the silicon of the silicon film with oxygen to selectively form a silicon oxide film on one principal surface of the substrate.

According to a tenth aspect of the present invention, a silicon film is selectively formed on one principal surface of a substrate having at least one principal surface made of a nitride III-V compound semiconductor, and then the substrate is exposed to at least nitrogen. A method of manufacturing a substrate for semiconductor growth, characterized in that a silicon nitride film is selectively formed on one main surface of the substrate by heating in an atmosphere containing silicon and reacting silicon of the silicon film with nitrogen. is there.

According to an eleventh aspect of the present invention, a silicon film is selectively formed on one main surface of at least one main surface made of a nitride III-V compound semiconductor, and then the substrate is subjected to a nitrogen plasma treatment. Reacting silicon of the silicon film with nitrogen to selectively form a silicon nitride film on one main surface of the substrate.

According to a twelfth aspect of the present invention, at least one main surface is made of a nitride III-V compound semiconductor, and one main surface is substantially provided with an inorganic mask as a mask for lateral epitaxial growth. A semiconductor device comprising: a substrate provided in a flat state; and a nitride III-V compound semiconductor layer epitaxially grown laterally on one main surface of the substrate.

In the present invention, the substrate for semiconductor growth comprises:
Typically used for growing nitride-based III-V compound semiconductors, it may be used for growing other semiconductors.

In the present invention, the nitride III-V compound semiconductor contains at least one group III element selected from the group consisting of Ga, Al, In and B and at least N, and optionally further contains As or And V-group elements including P. This nitride-based III-V compound semiconductor typically contains Ga. Specifically, for example, GaN, AlGaN, GaInN, AlG
aInN and the like.

In the present invention, the substrate is typically
Sapphire (single-crystal Al ₂ O ₃₎ nitride III-V compound semiconductor layer of single crystal on such a substrate, such as those growing the single crystal GaN layer. Also, this board
A sufficiently thick nitride III-V compound semiconductor layer, for example, a GaN layer may be used.

In the first and twelfth aspects of the present invention, "one main surface is substantially flat" means that the surface of the inorganic mask is in the same plane as the one main surface of the substrate, Surface is at a height different from that of the main surface of the substrate, but the difference in height between the surface of the inorganic mask and the main surface of the substrate may cause a difference between the growth layer and the inorganic mask during lateral epitaxial growth. Mean that the value is not more than a value at which no void is generated. The difference in height between the surface of the inorganic mask and one main surface of the substrate may differ depending on the material of the growth layer, the material of the inorganic mask, the width of the opening of the inorganic mask, and the like. Is 30 nm or less, more preferably 10 nm or less.

In the first and twelfth aspects of the present invention, the inorganic mask is typically a modified layer of a substrate, specifically, for example, a nitride III-V compound semiconductor constituting the substrate. And silicon oxide (SiO _x ), silicon nitride (SiN _x ), or a mixture thereof. Alternatively, the inorganic mask may be made of a silicon oxide film or a silicon nitride film formed at least on the surface by oxidizing or nitriding a silicon film selectively formed on one main surface of the substrate. Good.
The thickness of the inorganic mask can be freely selected within a range where the selectivity of growth required for performing lateral epitaxial growth on the semiconductor growth substrate can be freely selected. If the film quality is good, a thickness of one atomic layer or several atomic layers may be sufficient.

In the second to seventh aspects of the present invention, the introduction of silicon, oxygen or nitrogen to one main surface of the substrate is performed by:
An ion implantation method, an ion cluster beam method, a plasma doping method, or the like can be used.

In the third or eighth aspect of the present invention, the atmosphere containing oxygen may be an atmosphere containing O ₃ (ozone) in addition to an atmosphere containing O ₂ .

In the eighth to eleventh aspects of the present invention,
The silicon film basically has any crystallinity, but is typically amorphous or polycrystalline. The silicon film has a thickness such that a silicon oxide film or a silicon nitride film having a thickness required as an inorganic mask for lateral epitaxial growth is formed on one main surface of the substrate by a reaction between silicon of the silicon film and oxygen or nitrogen. And the height of the silicon oxide film or the silicon nitride film from one main surface of the substrate is set to a thickness that does not cause a gap between the growth layer and the inorganic mask when performing lateral epitaxial growth. Selected, usually SiO ₂ conventionally used as an inorganic mask
It is much thinner than a film. Specifically, the thickness of this silicon film is, for example, not less than the thickness of one atomic layer and 50
nm or less, preferably 30 nm or less, more preferably 10 n
m or less.

In the twelfth aspect of the present invention, the semiconductor device may be basically any device as long as it uses a nitride III-V compound semiconductor. Is a semiconductor light emitting device such as a semiconductor laser or a light emitting diode, or an electron transit device such as a GaN-based FET.

According to the first and twelfth aspects of the present invention, the inorganic mask as a mask for lateral epitaxial growth is provided with one main surface of the substrate being substantially flat. Thus, the conventional problem of using an SiO ₂ film formed by a CVD method as an inorganic mask can be solved at once. In other words, it is not necessary to perform extra growth by the thickness of the inorganic mask, or even if it is necessary to perform extra growth, it is only necessary to do so, so that the thickness of the grown layer can be reduced. There is no problem that the shape of the edge portion of the mask affects the propagation direction of defects in the growth layer, and there is very little possibility that a gap is formed between the growth layer and the inorganic mask.

The second to second embodiments of the present invention configured as described above.
According to the seventh invention, at least one principal surface is nitride-based II
By introducing silicon, oxygen, or the like to one main surface of the substrate made of an IV group compound semiconductor and then performing a heat treatment or a plasma treatment, an inorganic mask is substantially provided on one main surface of the substrate. It can be formed in a flat state.

The eighth to eighth aspects of the present invention configured as described above.
According to the eleventh aspect, at least one principal surface has a nitride-based I
The formation of a silicon film on one main surface of a substrate made of a II-V compound semiconductor and the subsequent oxidation or nitridation treatment provide an inorganic mask on one main surface of the substrate and a state in which one main surface of the substrate is substantially flat Can be formed.

[0032]

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

FIG. 1 shows a semiconductor growth substrate according to a first embodiment of the present invention.

As shown in FIG. 1, in the semiconductor growth substrate according to the first embodiment, a single-crystal GaN layer 2 is laminated on a sapphire substrate 1 having, for example, a c-plane orientation. An inorganic mask 3 having a line-and-space shape is provided with the surface of the GaN layer 2 being substantially flat. This inorganic mask 3 is made of GaN with Si
O _x component consisting mixed reformed layer. The thickness of the GaN layer 2 is, for example, 2 μm. The line width and space width of the inorganic mask 3 are, for example, 0.5 μm and 1 μm, respectively.

Next, a method of manufacturing the semiconductor growth substrate configured as described above will be described.

First, as shown in FIG. 2A, a GaN layer 2 is epitaxially grown on a sapphire substrate 1. For the epitaxial growth of the GaN layer 2, for example, a metal organic chemical vapor deposition (MOCVD) method is used. As an example of the growth conditions of the GaN layer 2, trimethyl gallium (TMG) and ammonia (NH ₃ ) are used as growth raw materials, and their flow rates are 50 SCCM and 20 SCCM, respectively.
SLM, reaction pressure 500 Torr, substrate temperature 7
The temperature is set to 00 to 1000 ° C.

Next, as shown in FIG. 2B, a resist pattern 4 having a predetermined line and space shape is formed on the GaN layer 2 by photolithography using ultraviolet rays. The formation of the resist pattern 4 is specifically performed as follows. That is, first, a positive resist is applied to the entire surface of the GaN layer 2, and the resist is exposed to g-line (wavelength: 436 nm) by a high-pressure mercury lamp using a predetermined photomask in a mask aligner. Is performed to form a resist pattern 4. The line width and space width of the resist pattern 4 are, for example, 1 μm and 0.5 μm, respectively.

Next, the G on which the resist pattern 4 is formed
Silicon (Si) is ion-implanted over the entire surface of the aN layer 2 (in FIG. 2B, the Si implanted in the GaN layer 2 is indicated by.). The acceleration energy of the ion implantation of Si is set low so that the Si concentration near the surface of the GaN layer 2 is increased in order to efficiently form the inorganic mask 3, and specifically, is selected, for example, to 20 keV. The dose is selected to be, for example, 1 × 10 ¹⁷ cm ⁻² .

Next, as shown in FIG. 2C, oxygen (O) is ion-implanted into the entire surface of the GaN layer 2 on which the resist pattern 4 has been formed (in FIG. 2C, O implanted into the GaN layer 2).
Is indicated by x). The acceleration energy of the O ion implantation depends on the distribution of Si implanted on the surface of the GaN layer 2 and the distribution of O
Are selected so as to overlap with each other, and specifically, for example, 10
keV, and the dose is, for example, 2 of the dose of Si.
2 × 10 ¹⁷ cm ^-2 times.

Next, after removing the resist pattern 4,
As shown in FIG. 2D, the sapphire substrate 1 is heated, for example, in an annealing
SiO _x is formed by reacting Si and O injected into the N layer 2 to form an inorganic mask 3 made of a modified layer in which GaN is mixed with a SiO _x component. The heating temperature is between Si and O
Is required to be higher than the temperature at which SiO _x is formed by the reaction with, for example, about 800 ° C. The heating time is, for example, 30 minutes.

As described above, the intended substrate for semiconductor growth as shown in FIG. 1 is easily manufactured.

As described above, according to the first embodiment, the inorganic mask 3 is provided on the surface of the GaN layer 2 on the surface of the GaN layer 2.
When the lateral epitaxial growth of a GaN-based semiconductor is performed on the semiconductor growth substrate, the GaN-based semiconductor is provided with a thickness of the inorganic mask 3 which is different from the conventional method. Therefore, there is no need to perform extra epitaxial growth by that much, and there is no possibility that the shape of the edge portion of the inorganic mask 3 will affect the propagation direction of the defect. Further, a gap is formed between the regrown layer and the inorganic mask 3. Very unlikely to occur.

Next, a second embodiment of the present invention will be described. In the second embodiment, another method for manufacturing the semiconductor growth substrate according to the first embodiment will be described.

In the second embodiment, as shown in FIG. 3A, first, a GaN layer 2 is epitaxially grown on a sapphire substrate 1. For the epitaxial growth of the GaN layer 2, for example, the MOCVD method is used. This G
The growth conditions for the aN layer 2 are the same as in the first embodiment.

Next, as shown in FIG. 3B, a resist pattern 4 having a predetermined line and space shape is formed on the GaN layer 2 by photolithography using ultraviolet rays. The method of forming the resist pattern 4 is the same as in the first embodiment.

Next, the G on which the resist pattern 4 is formed is formed.
Si ions are implanted into the entire surface of the aN layer 2 (G in FIG. 3B).
Si implanted in the aN layer 2 is indicated by.). The conditions for this Si ion implantation are the same as in the first embodiment.

Next, after removing the resist pattern 4,
As shown in FIG. 3C, the sapphire substrate 1 is
In a state where the sapphire substrate 1 is heated to about 800 ° C., O ₂ gas is flowed into the annealing furnace 5 to set the pressure at 760 Torr and hold for 60 minutes. As a result, Si injected into the GaN layer 2 reacts with O ₂ in the annealing furnace 5 to form SiO _x, and SiO ₂ is formed on the GaN.
_An inorganic mask 3 composed of a modified layer mixed with the _x component is formed.

Thus, the intended substrate for semiconductor growth as shown in FIG. 1 is manufactured.

As described above, according to the second embodiment, the semiconductor growth substrate according to the first embodiment can be easily manufactured by an ion implantation technique, a heat treatment technique, or the like.

Next, a third embodiment of the present invention will be described. In the third embodiment, still another method of manufacturing the semiconductor growth substrate according to the first embodiment will be described.

In the third embodiment, instead of oxidizing by flowing O ₂ gas in the annealing furnace 5 in the second embodiment, an oxygen plasma treatment is performed in a chamber (not shown), so that a GaN layer is formed. 2 to react with the Si implanted into the O ₂ to form SiO _x ,
An inorganic mask 3 made of a modified layer in which N is mixed with a SiO _x component is formed. As an example of the conditions of the oxygen plasma treatment, O ₂ gas is flowed into the annealing furnace 5 at 500 SCCM, the pressure is maintained at 300 mTorr, and 13.56 MHz.
From the RF power source was charged with power 500W of to generate O ₂ plasma between the parallel plate electrodes, the sapphire substrate 1 held 10 minutes in the O ₂ plasma. The other points are the same as those of the method for manufacturing the semiconductor growth substrate according to the first embodiment, and a description thereof will not be repeated.

Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, still another method of manufacturing the semiconductor growth substrate according to the first embodiment will be described.

In the fourth embodiment, as shown in FIG. 4A, first, a GaN layer 2 is epitaxially grown on a sapphire substrate 1. For the epitaxial growth of the GaN layer 2, for example, the MOCVD method is used. This G
The growth conditions for the aN layer 2 are the same as in the first embodiment.

Next, as shown in FIG. 4B, a resist pattern 4 having a predetermined line and space shape is formed on the GaN layer 2. The method of forming the resist pattern 4 is the same as in the first embodiment.

Next, as shown in FIG. 4C, a sufficiently thin hydrogenated amorphous Si (a) is formed on the entire surface of the GaN layer 2 on which the resist pattern 4 is formed, for example, by a plasma CVD method.
-Si: H) film 6 is formed. The thickness of the a-Si film 6 is, for example, 5 nm.

Next, as shown in FIG. 4D, the resist pattern 4 is removed by a lift-off method, so that the line-and-space a-Si: H film 6 is made of GaN.
Leave on layer 2. Specifically, for example, the sapphire substrate 1
By immersing in acetone and applying ultrasonic vibration
A-Si: H film formed on the resist pattern 4
A removed directly with the film 6 and directly formed on the GaN layer 2
By leaving only the -Si: H film 6, a line-and-space a-Si: H film 6 is obtained.

Next, as shown in FIG. 4E, the sapphire substrate 1 is placed in an annealing furnace 5, and while the sapphire substrate 1 is heated to about 800 ° C., O ₂ is placed in the annealing furnace 5.
The pressure is set to 760 Torr by flowing gas, and the pressure is maintained for 30 minutes. As a result, Si of the a-Si: H film 6 reacts with O ₂ in the annealing furnace to form SiO _x ,
An inorganic mask 3 composed of a modified layer in which a SiO _x component is mixed in aN is formed.

Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, as shown in FIG. 5, a GaN layer 7 is laterally epitaxially grown on the semiconductor growth substrate according to the first embodiment by, for example, the MOCVD method.

According to the fifth embodiment, the inorganic mask 3 is provided on the surface of the GaN layer 2 of the semiconductor growth substrate.
Since the surface of the layer 2 is provided in a substantially flat state, the thickness of the GaN layer 7 regrown on the substrate can be reduced, and the angle of the edge portion of the inorganic mask 3 can be reduced. Does not affect the propagation direction of defects in the GaN layer 7, and the GaN layer 7 and the inorganic mask 3
It is very unlikely that a gap is formed between the first and second layers.

Next, G according to the sixth embodiment of the present invention will be described.
The aN-based semiconductor laser will be described. FIG.
1 shows an N-based semiconductor laser. This GaN semiconductor laser has a ridge structure and a SCH (Separate Confinement Heter).
ostructure).

As shown in FIG. 6, in this GaN-based semiconductor laser, a substrate similar to the semiconductor growth substrate according to the first embodiment is used. That is, for example, c
A single-crystal GaN layer 22 on a sapphire substrate 21 having a plane orientation
And a line-and-space-shaped inorganic mask 23 is provided on the surface of the GaN layer 22 with the surface of the GaN layer 22 being substantially flat. This inorganic mask 23 is composed of a modified layer in which GaN is mixed with a SiO _x component. The thickness of the GaN layer 22 is, for example, 2 μm. The line width and space width of the inorganic mask 23 are, for example, 0.5 μm and 1 μm, respectively.

Then, the Ga on which the inorganic mask 23 is formed is formed.
An undoped GaN layer 24, an n-type GaN contact layer 25, an n-type AlGaN cladding layer 26, an n-type G
aN optical waveguide layer 27, Ga _1-x In _x N / Ga _1-y In _y
N-quantum well active layer 28, p-type AlGaN cap layer 29, p-type GaN optical waveguide layer 30, p-type AlGaN
A cladding layer 31 and a p-type GaN contact layer 32 are sequentially stacked. Here, the p-type AlGaN cap layer 29 is formed by forming the p-type GaN optical waveguide layer 30, the p-type AlGaN cladding layer 31, and the p-type GaN contact layer 32 by 100.
When growing at a temperature of about 0 ° C., Ga _1-x In _x N / G
a _1-y In _y N from the active layer 28 having a multiple quantum well structure
This is for preventing N from being decomposed.

The upper part of the n-type GaN contact layer 25, n
-Type AlGaN cladding layer 26, n-type GaN optical waveguide layer 2
_{7, Ga 1-x In x} N / Ga 1-y In y N multi quantum well active layer 28 of the structure, p-type AlGaN cap layer 29, p
-Type GaN optical waveguide layer 30, p-type AlGaN cladding layer 31
The p-type GaN contact layer 32 has a mesa shape having a predetermined width. The upper layer of the p-type AlGaN cladding layer 31 and the p-type GaN contact layer 3
2 is formed with a ridge portion 33 having a predetermined width extending in one direction. An insulating film 33 such as a SiO ₂ film is provided on the surface of the mesa portion and on the surface of the n-type GaN contact layer 25 other than the mesa portion. In the insulating film 33, an opening 34a is provided in a portion above the ridge portion 33, and an opening 34b is provided in a portion adjacent to the mesa portion above the n-type GaN contact layer 25. Further, a p-side electrode 35 is provided so as to straddle the ridge portion 33, and has an ohmic contact with the p-type GaN contact layer 32 of the ridge portion 33 through the opening 34 a of the insulating film 34. Further, the n-type GaN contact layer 2 is formed through the opening 34b of the insulating film 34.
On n, an n-side electrode 36 is provided in ohmic contact.

Next, a method of manufacturing the GaN-based semiconductor laser according to the sixth embodiment configured as described above will be described.

In order to manufacture this GaN-based semiconductor laser, first, a GaN semiconductor laser in which an inorganic mask 23 is selectively formed is used.
An undoped GaN layer 24 is laterally epitaxially grown on the layer 22 by MOCVD. Next, n-doped GaN layer 24 is
-Type GaN contact layer 25, n-type AlGaN cladding layer 26, n-type GaN optical waveguide layer 27, Ga _1-x In _x N / G
a _1-y In _y N Multiple quantum well structure active layer 28, p-type A
lGaN cap layer 29, p-type GaN optical waveguide layer 30, p
The AlGaN cladding layer 31 and the p-type GaN contact layer 32 are sequentially grown. Here, an undoped GaN layer 24 which is a layer not containing In, an n-type GaN contact layer 25, an n-type AlGaN cladding layer 26, an n-type GaN optical waveguide layer 27, a p-type AlGaN cap layer 29, a p-type Ga
The growth temperature of the N optical waveguide layer 30, the p-type AlGaN cladding layer 31, and the p-type GaN contact layer 32 is about 1000 ° C., and the layer containing In is Ga _1-x In _x N / Ga
The growth temperature of the active layer 28 having the _1-y In _y N multiple quantum well structure is set to 700 to 800 ° C. The growth raw materials of these GaN-based semiconductor layers are, for example, trimethylgallium (TMG) as a raw material of a group III element Ga, trimethylaluminum (TMA) as a raw material of a group III element Al, and a group III element. The raw material of In is trimethylindium (TMI) and the group V element N
Ammonia (NH ₃ ) is used as a raw material for the above. Also,
As the carrier gas, for example, a mixed gas of hydrogen (H ₂ ) and nitrogen (N ₂ ) is used. As for the dopant, for example, monosilane (SiH
₄ ), and, for example, methylcyclopentadienyl magnesium ((MCp) ₂ Mg) is used as a p-type dopant.

Next, an SiO ₂ film having a thickness of, for example, 0.4 μm is formed on the entire surface of the p-type GaN contact layer 32 by, for example, a CVD method, a vacuum evaporation method, a sputtering method, or the like, and then lithography is performed on the SiO ₂ film. To form a resist pattern (not shown) having a predetermined shape, and using the resist pattern as a mask, the SiO ₂ film is etched by wet etching using, for example, a hydrofluoric acid-based etchant. Thereby, the p-type GaN contact layer 3
2, an etching mask made of a SiO ₂ film is formed.

Next, using this etching mask, n-type Ga is formed by, for example, a reactive ion etching (RIE) method.
The etching is performed until reaching the N contact layer 25. At this time, for example, the n-type GaN contact layer 25 has a thickness of 0.5
μm is etched. As the RIE etching gas, for example, a chlorine-based gas is used.

Next, after the etching mask is removed by etching, the entire surface of the substrate is again subjected to, for example, CVD, vacuum evaporation,
After forming a SiO ₂ film having a thickness of, for example, 0.2 μm by a sputtering method or the like, a resist pattern (not shown) having a predetermined shape is formed on the SiO ₂ film by lithography.
Is formed, and the SiO ₂ film is etched by wet etching using, for example, a hydrofluoric acid-based etchant using the resist pattern as a mask. Thus, an etching mask made of the SiO ₂ film is formed on the surface of the substrate including the mesa.

Next, using this etching mask, the ridge portion 33 is formed by performing etching to a predetermined depth in the thickness direction of the p-type GaN contact layer 32 by, for example, RIE. As the RIE etching gas, for example, a chlorine-based gas is used.

Next, a resist pattern (not shown) is formed by lithography to cover the surface of the region excluding the n-side electrode formation region.

Next, by using the resist pattern as a mask, the insulating film 34 is etched to form the opening 34b.
To form

Next, with the resist pattern left, a Ti film, A
After sequentially forming an l film, a Pt film and an Au film, the resist pattern is removed together with the Ti film, Al film, Pt film and Au film formed thereon (lift-off). Thereby, the n-type G in the portion of the opening 34b of the insulating film 34
An n-side electrode 36 having a Ti / Al / Pt / Au structure is formed on the aN contact layer 25.

Next, for example, by performing a heat treatment at 800 ° C. for 10 minutes in a nitrogen gas atmosphere, the p-type AlG
aN cap layer 29, p-type GaN optical waveguide layer 30, p-type A
The p-type impurity doped in the lGaN cladding layer 31 and the p-type GaN contact layer 32 is electrically activated, and the n-side electrode 36 is alloyed.

Next, the ridge 33 is formed by lithography.
A resist pattern (not shown) is formed to cover the surface of the region excluding the region.

Next, using the resist pattern as a mask, the insulating film 34 is etched to form an opening 34 a, exposing the upper surface of the ridge 33.

Next, a resist pattern (not shown) is formed by lithography to cover the surface of the region excluding the p-side electrode formation region.

Next, after a Ni film, a Pt film and an Au film are sequentially formed on the entire surface of the substrate by, for example, a vacuum evaporation method, the resist pattern is removed together with the Ni film, the Pt film and the Au film formed thereon. As a result, the ridge 33
, A p-side electrode 35 having a Ni / Pt / Au structure is formed. Next, for example, by performing a heat treatment at 600 ° C. for 20 minutes in a nitrogen gas atmosphere, the p-side electrode 3 is formed.
5 alloy processing is performed.

Thereafter, the c-plane sapphire substrate 21 on which the laser structure is formed as described above is processed into a bar shape to form both resonator end faces, and after the end face coating is performed, the bar is formed into chips. I do. Thus, the intended GaN-based semiconductor laser having the ridge structure and the SCH structure is manufactured.

According to the sixth embodiment, the undoped GaN layer 24 can be grown with good crystallinity by lateral epitaxial growth on the GaN layer 22 on which the inorganic mask 23 is selectively formed. The GaN-based semiconductor layer grown on the GaN-based semiconductor layer can also have good crystallinity, so that a GaN-based semiconductor laser having good characteristics can be manufactured.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above embodiments, and various modifications based on the technical concept of the present invention are possible.

For example, the numerical values, materials, shapes, structures, raw materials, processes, and the like described in the first to sixth embodiments are merely examples, and different numerical values, materials, and shapes may be used as necessary. , Structures, raw materials, processes and the like may be used.

Specifically, in the above-described first to sixth embodiments, M is used for epitaxial growth of a GaN-based semiconductor.
Although the OCVD method is used, for example, a hydride vapor phase epitaxial growth (HVPE) method may be used for the epitaxial growth of the GaN-based semiconductor, and further, a molecular beam epitaxy (MBE) method may be used.

In the above-described second embodiment,
The sapphire substrate 1 in which Si has been selectively ion-implanted into the GaN layer 2 is heated in an O ₂ gas atmosphere to thereby obtain Si.
Although the inorganic mask 3 is formed by forming O _x , the inorganic mask 3 may be formed by heating in an O ₃ gas atmosphere to form SiO _x . As an example of the conditions at this time, the heating temperature is 400 ° C., the pressure is normal pressure, and the heating time is 60 minutes.

[0084]

As described above, according to the substrate for semiconductor growth of the present invention, an inorganic mask as a mask for lateral epitaxial growth is provided on one main surface of the substrate, and the one main surface is substantially flat. By being provided in a state, when performing lateral epitaxial growth thereon,
The thickness of the growth layer can be reduced, and there is no problem that the shape of the edge portion of the inorganic mask affects the direction of propagation of defects in the growth layer, and further, a gap is generated between the growth layer and the inorganic mask. There is no fear.

According to the method of manufacturing a substrate for semiconductor growth according to the present invention, an inorganic mask as a mask for lateral epitaxial growth is formed on the one main surface of a substrate having at least one main surface made of a nitride III-V compound semiconductor. However, it is possible to easily manufacture a semiconductor growth substrate provided with the one main surface being substantially flat.

According to the semiconductor device of the present invention, the inorganic mask as a mask for lateral epitaxial growth is provided on one main surface of the substrate with the one main surface substantially flat. The semiconductor layer grown laterally epitaxially on the substrate has good crystallinity, so that the element layer grown on this semiconductor layer also has good crystallinity, thereby realizing a semiconductor device with good characteristics. can do.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a semiconductor growth substrate according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining the method for manufacturing a semiconductor growth substrate according to the first embodiment of the present invention.

FIG. 3 is a sectional view for explaining a method of manufacturing a semiconductor growth substrate according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view for explaining a method for manufacturing a semiconductor growth substrate according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view for explaining a method for manufacturing a semiconductor growth substrate according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view showing a GaN-based semiconductor laser according to a sixth embodiment of the present invention.

[Explanation of symbols]

1, 21, sapphire substrate, 2, 7, GaN
Layer, 3, 23 ... inorganic mask, 24 ... undoped GaN layer

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 5F041 AA40 CA04 CA05 CA34 CA40 CA46 CA54 CA57 CA65 CA71 CA73 CA74 CA77 CB05 5F045 AA04 AB04 AB09 AB14 AB17 AC01 AC08 AC09 AC11 AD08 AD11 AD12 AD13 AF04 AF09 AF20 BB12 DC68 HA15

Claims (23)

[Claims] At least one principal surface is a nitride III-V
A substrate for semiconductor growth, wherein an inorganic mask as a mask for lateral epitaxial growth is provided on the one main surface of the substrate made of a group III compound semiconductor, with the one main surface being substantially flat. 2. The semiconductor growth substrate according to claim 1, wherein said inorganic mask comprises a modified layer of said substrate. 3. The method according to claim 1, wherein the inorganic mask is formed of the nitride III-
2. The semiconductor growth substrate according to claim 1, wherein the substrate is made of a mixture of a group V compound semiconductor and silicon oxide and / or silicon nitride. 4. At least one principal surface is a nitride III-V
After selectively introducing silicon and oxygen to the one main surface of the substrate made of a group III compound semiconductor, heating the substrate to cause the silicon and the oxygen to react with each other, thereby forming silicon oxide on the one main surface of the substrate. Characterized by selectively forming a substrate. 5. The method according to claim 4, wherein said silicon and said oxygen are selectively introduced into said one main surface of said substrate by an ion implantation method, an ion cluster beam method or a plasma doping method. A method for manufacturing a semiconductor growth substrate. 6. At least one principal surface is a nitride III-V
After selectively introducing silicon to the one main surface of the substrate made of a group III compound semiconductor, the substrate is heated in an atmosphere containing at least oxygen to react the silicon with the oxygen, thereby causing the substrate to react with the oxygen. A method for manufacturing a semiconductor growth substrate, wherein silicon oxide is selectively formed on a main surface. 7. The semiconductor growth device according to claim 6, wherein said silicon is selectively introduced into said one main surface of said substrate by an ion implantation method, an ion cluster beam method or a plasma doping method. Substrate manufacturing method. 8. At least one principal surface is composed of a nitride III-V.
After selectively introducing silicon to the one main surface of the substrate made of a group III compound semiconductor, the substrate is subjected to oxygen plasma treatment to react the silicon and the oxygen, thereby forming silicon oxide on the one main surface of the substrate. Characterized by selectively forming a substrate. 9. The semiconductor growth device according to claim 8, wherein said silicon is selectively introduced into said one main surface of said substrate by an ion implantation method, an ion cluster beam method or a plasma doping method. Substrate manufacturing method. 10. At least one principal surface is composed of a nitride III-
After selectively introducing silicon and nitrogen to the one main surface of the substrate made of a group V compound semiconductor, the substrate is heated to cause the silicon and the nitrogen to react with each other, thereby nitriding the one main surface of the substrate. A method for manufacturing a substrate for semiconductor growth, wherein silicon is selectively formed. 11. The method according to claim 10, wherein said silicon and said nitrogen are selectively introduced into said one main surface of said substrate by an ion implantation method, an ion cluster beam method or a plasma doping method. A method for manufacturing a semiconductor growth substrate. 12. A method according to claim 1, wherein at least one principal surface is a nitride III-
After selectively introducing silicon to the one main surface of the substrate made of a group V compound semiconductor, the substrate is heated in an atmosphere containing at least nitrogen to react the silicon with the nitrogen, thereby causing the silicon to react with the nitrogen. A method for manufacturing a semiconductor growth substrate, wherein silicon nitride is selectively formed on one principal surface. 13. The semiconductor growth method according to claim 12, wherein said silicon is selectively introduced into said one main surface of said substrate by an ion implantation method, an ion cluster beam method or a plasma doping method. Substrate manufacturing method. 14. At least one principal surface is a nitride III-
After selectively introducing silicon to the one main surface of the substrate made of a group V compound semiconductor, the substrate is subjected to nitrogen plasma treatment to react the silicon and the nitrogen, thereby nitriding the one main surface of the substrate. A method for manufacturing a semiconductor growth substrate, wherein silicon is selectively formed. 15. The semiconductor growth method according to claim 14, wherein said silicon is selectively introduced into said one main surface of said substrate by an ion implantation method, an ion cluster beam method or a plasma doping method. Substrate manufacturing method. 16. At least one principal surface is composed of a nitride III-
After selectively forming a silicon film on the one main surface of the substrate made of a group V compound semiconductor, heating the substrate in an atmosphere containing at least oxygen to react silicon in the silicon film with the oxygen. Wherein a silicon oxide film is selectively formed on the one main surface of the substrate. 17. At least one principal surface is composed of a nitride III-
After selectively forming a silicon film on the one main surface of the substrate made of a group V compound semiconductor, the substrate is subjected to oxygen plasma treatment to react the silicon of the silicon film with the oxygen, thereby forming the silicon substrate. A method for manufacturing a semiconductor growth substrate, wherein a silicon oxide film is selectively formed on one principal surface. 18. At least one principal surface of a nitride III-
After selectively forming a silicon film on the one main surface of the substrate made of a group V compound semiconductor, heating the substrate in an atmosphere containing at least nitrogen to react silicon in the silicon film with the nitrogen. Wherein a silicon nitride film is selectively formed on the one main surface of the substrate. 19. At least one principal surface is a nitride III-
After selectively forming a silicon film on the one main surface of the substrate made of a group V compound semiconductor, the substrate is subjected to a nitrogen plasma treatment to react the silicon of the silicon film with the nitrogen, thereby forming the silicon substrate. A method for manufacturing a semiconductor growth substrate, wherein a silicon nitride film is selectively formed on one principal surface. 20. A semiconductor device using a nitride III-V compound semiconductor, wherein at least one main surface is made of a nitride III-V compound semiconductor, and the one main surface is used as a mask for lateral epitaxial growth. An inorganic mask comprising: a substrate provided with the one main surface substantially flat; and a nitride III-V compound semiconductor layer laterally epitaxially grown on the one main surface of the substrate. A semiconductor device characterized by the above-mentioned. 21. The semiconductor device according to claim 20, wherein said inorganic mask comprises a modified layer of said substrate. 22. The method according to claim 19, wherein the inorganic mask is made of the nitride III.
21. A mixture of -V compound semiconductor and silicon oxide or silicon nitride.
13. The semiconductor device according to claim 1. 23. The semiconductor device according to claim 20, wherein said semiconductor device is a semiconductor light emitting element.