JPH1041586A - Method of forming light emissive end face of semiconductor light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emissive end face formation method which can form, by cleavage, the light emissive end face of a semiconductor light emitting element using a nitride group III-V compound semiconductor without using an expensive substrate such as an SIC substrate or the like, and enables the takeout of an electrode to be performed from both sides of top and bottom, and does not hinder the movement of the semiconductor light emitting element, either. SOLUTION: Laser structure is made by stacking GaN semiconductor layers in multilayer on a C-face sapphire substrate 1, and then an Ni/Au film 7 is made thereon. An Ni/Au/In film 9 is made on a p-type GaP substrate 8 of (100) face azimuth. The GaN semiconductor layer on the C-face sapphire substrate 1 and the p-type GaP substrate 8 are joined with each other through the Ni/Au film 7 and the Ni/Au/In film 9. At that time, the direction where the cleavage of the p-type GaP substrate 8 is easy and the direction where the cleavage of the GaN semiconductor layer is easy are conformed to each other. After joining, the end face of the resonator, that is, the light emissive end face is made by removing the C-face sapphire substrate 1, and cleaving the p-type GaP substrate 8 in the direction where the cleavage is easy thereby cleaving the GaN semiconductor layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a light emitting end face of a semiconductor light emitting device using a nitride III-V compound semiconductor such as GaN.

[0002]

2. Description of the Related Art Nitride (nitride) -based III-V compound semiconductors such as GaN, AlGaN, and GaInN have band gaps ranging from 1.8 eV to 6.2 eV, and emit red to ultraviolet light. In recent years, attention has been paid to the realization of a possible light-emitting element because it is theoretically possible.

When a light emitting diode (LED), a semiconductor laser, or the like is manufactured from the nitride III-V compound semiconductor, GaN, AlGaN, GaInN, etc. are laminated in multiple layers, and the light emitting layer (active layer) is n. It is necessary to form a structure sandwiched between the mold cladding layer and the p-cladding layer.

When manufacturing a semiconductor laser,
It is necessary to form a cavity end face, that is, a light emission end face,
This end face formation is usually performed by cleavage. Therefore, it has been attempted to form an end face by cleavage also in a GaN-based semiconductor laser.

On the other hand, as one main substrate used for crystal growth of a GaN-based semiconductor, a so-called 6H (000
1) Although there is a plane SiC substrate, the 6H (0001) plane S
The iC substrate and the GaN-based semiconductor grown thereon have the same in-plane axial direction, and are cleaved along the {2-1-10} plane (called “A plane”).

A sapphire substrate is another main substrate used for crystal growth of a GaN-based semiconductor. The sapphire substrate is less expensive than a SiC substrate, and a large sapphire substrate is commercially available. A GaN-based LED manufactured using this sapphire substrate is already on the market.

From an industrial point of view, it is very significant to realize a GaN-based semiconductor laser using this inexpensive sapphire substrate. However, a frequently used (0001) plane (called “C plane”) sapphire substrate does not have a cleavage axis in that plane.
By growing the GaN-based semiconductor layer constituting the laser structure on the sapphire substrate and then cleaving the substrate, it is not possible to form a good light emitting end face. $ 1
It is said that a 1-20 ° sapphire substrate (called “A-plane”) can be easily cleaved by using a sapphire substrate, but a practically satisfactory one has not been obtained.

Therefore, Ga is placed on the C-plane sapphire substrate.
In a GaN-based semiconductor laser formed by growing an N-based semiconductor, Ga on a C-plane sapphire substrate is used.
After the N-based semiconductor layers are grown to form a laser structure, these GaN-based semiconductor layers are subjected to reactive ion etching (R
The light-emitting end face is formed by vapor phase etching using the IE) method (for example, Jpn. J. Appl. Phys. 35 (1996)).
L74).

However, since the GaN-based semiconductor is a very hard substance, the etching selectivity with respect to a mask used for etching is as small as about 4, and a good light emitting end face has not been obtained. Further, the unevenness formed on the light emitting end face is so large as to cause light scattering.

Further, since the sapphire substrate is an electrically insulating substrate, the two terminals of the GaN semiconductor laser formed thereon must be taken out from the upper surface. No. Further, when a GaN-based semiconductor laser is installed face-down, a more advanced technique must be used than when a GaAs-based semiconductor laser or the like is installed face-down.

On the other hand, recently, using a bonding technique of a substrate,
Attempts have been made to form an end face composed of a cleavage plane in the aN layer (Appl. Phys. Lett. 68 (1996) 2147). According to this method, a GaN layer is grown on a C-plane sapphire substrate, and an InP substrate is pressure-bonded to the surface of the GaN layer at 750 ° C.
They are joined by performing a heat treatment for
After the plane sapphire substrate is wrapped from its back side to reduce its thickness to a thickness sufficient for cleavage, the GaN layer and the C-plane sapphire substrate are cleaved to form an end face composed of a cleavage plane on the GaN layer. In this document, a junction between an n-type GaN layer and an n-type InP layer is formed by this method. However, this n-type GaN / n
The current-voltage characteristics of the type InP junction become diode characteristics, which indicates that there is a potential barrier when electrons move from the n-type InP layer side to the n-type GaN layer side.

By the way, in a semiconductor laser, usually,
The p layer is on the surface side. Therefore, the above InP
When a semiconductor laser is manufactured by using a substrate bonding technique, it is necessary to use a p-type InP substrate. However, when a p-type InP substrate is used, a very serious problem occurs. That is, the connection of the energy band between GaN and InP is not clear at present, but according to calculations, it is expected that the valence band of GaN will be very low due to the large electronegativity of N (Jpn.J .Appl.P
hys.32 (1993) 4413). There is also a report based on the energy level of Fe in a semiconductor (Materials Science an
d Engineering B29 (1995) 61), which states that the energy difference at the top of the valence band between GaN and InP is 1.7 eV.
It is. According to these, the band connection between GaN and InP is expected to be as shown in FIG. 12 and FIG. Here, FIG. 12 shows Ga by a flat band model.
FIG. 13 shows a band connection between N and InP, and FIG.
4 shows a band connection between P-type and p-type InP. In FIGS. 12 and 13, E _c is the energy at the lower end of the conduction band,
E _v indicates the energy at the upper end of the valence band, and E _F indicates the Fermi energy. In FIG. 12, E _g1 = 3.4.
eV, E _g2 = 1.34 eV, ΔE _c = 0.36 eV, Δ
E _v = 1.7 eV.

As can be seen from FIG. 13, when holes are injected from the p-type InP side, a barrier .DELTA.E for holes having a height of 1 eV or more is formed.
The operation of the semiconductor laser is considered difficult in practice.

[0014]

As described above, conventionally, a method of forming a light-emitting end face of a semiconductor laser by cleavage using an inexpensive substrate such as a sapphire substrate without causing restrictions on electrode extraction or the like. There was no.

Accordingly, an object of the present invention is to provide a nitride-based III-substrate without using an expensive substrate such as a SiC substrate.
A semiconductor light emitting device using a group V compound semiconductor, in which a light emitting end face of the semiconductor light emitting device can be formed by cleavage, and furthermore, electrodes can be taken out from both upper and lower surfaces, so that operation of the semiconductor light emitting device is not hindered; It is another object of the present invention to provide a method for forming a light emitting end face.

[0016]

To achieve the above object, the present invention relates to a method for forming a light emitting end face of a semiconductor light emitting device using a nitride III-V compound semiconductor. The nitride III-V compound semiconductor layer of the first substrate, on which a nitride III-V compound semiconductor layer to be grown is grown on one main surface thereof, is cleaved via a conductive intermediate layer. The first substrate is bonded to one main surface of the second substrate so that the direction of easy cleavage of the second substrate substantially coincides with the direction of easy cleavage of the nitride III-V compound semiconductor layer. Aligning the first substrate with the second substrate, removing or thinning the first substrate from the other main surface side, and nitriding the second substrate by cleaving along the easy cleavage direction. Cleaving the compound III-V compound semiconductor layer It is characterized in that a step of forming a discharge end face.

In the present invention, the first substrate may be basically any material as long as a nitride III-V compound semiconductor layer can be grown thereon. Specific examples of the first substrate include a sapphire substrate, a spinel substrate, and the like.

In the present invention, the second substrate typically has conductivity. As the second substrate, for example, a single crystal substrate made of Si, Ge, or a group III-V compound semiconductor is used. As the III-V group compound semiconductor, GaP, GaAs, InP, InAs,
GaSb and the like can be mentioned.

In the present invention, the conductive intermediate layer is preferably made of a metal film, typically a metal film having a multilayer structure. The conductive intermediate layer is made of, for example, a nitride-based
A first metal film is formed in advance on the II-V compound semiconductor layer, and a second metal film is formed in advance on one main surface of the second substrate. Further, the conductive intermediate layer may be made of a metal film formed in advance on one of the nitride-based III-V compound semiconductor layer and one of the main surfaces of the second substrate. There may be.

In the present invention, the nitride-based III-V compound semiconductor layer contains at least Ga and N, and optionally further contains at least one group III element selected from the group consisting of Al, In and B and / or Or, it contains at least one group V element selected from the group consisting of As and P. Specific examples of the nitride III-V compound semiconductor layer include a GaN layer, an AlGaN layer, a GaInN layer,
An AlGaInN layer or the like.

In the present invention, for example, a nitride-based II
The group IV-compound semiconductor layer is a growth layer having a (0001) orientation, and when the second substrate has a cubic crystal structure, the <1-- 100> direction or <2-1-10> direction and second
The first substrate and the second substrate are aligned with each other so that the <110> direction of the substrate substantially matches. In the case where the [0001] direction of the nitride-based III-V compound semiconductor layer is parallel to one main surface of the first substrate and the second substrate has a cubic crystal structure, System I
The direction perpendicular to the [0001] direction of the II-V compound semiconductor layer, the <1-100> direction or the <2-1-10> direction is substantially the same as the <110> direction of the second substrate. The first substrate and the second substrate are aligned with each other.

In the present invention, typically, a current blocking layer in the vertical direction is formed by partially forming a current blocking layer in a nitride III-V compound semiconductor layer.
As the current confinement structure, those generally used in semiconductor lasers can be used. Specifically, an insulating film method, an ion implantation method, an internal confinement method, a buried hetero (BH, Buried Hetero) structure A current confinement structure by a method or the like can be used.

In the present invention, for example, after removing the first substrate, an ohmic or Schottky electrode is formed on the nitride-based III-V compound semiconductor layer.

In the present invention, preferably, a control circuit for the semiconductor light emitting device is formed on the second substrate, and the control circuit is connected to the semiconductor light emitting device via the conductive intermediate layer. This control circuit is, specifically, a signal processing circuit,
It consists of a high-frequency superimposing circuit, a power supply circuit, a light detection circuit, and the like.

In the present invention configured as described above, the nitride III-V compound semiconductor layer grown on the first substrate is joined to the second substrate having a cleavage property to form the first substrate. After removing or thinning the substrate, the second substrate is cleaved to cleave the nitride-based III-V compound semiconductor layer to form a light emitting end face.
A sapphire substrate or the like can be used as the substrate, and a GaP substrate or the like can be used as the second substrate. Inexpensive substrates can be used for both the first substrate and the second substrate. In addition, by using a conductive material as the second substrate, electrodes can be taken out from both upper and lower surfaces, and face-down installation can be easily performed. Further, by joining the nitride III-V compound semiconductor layer and the second substrate via a conductive intermediate layer, particularly a metal film, the nitride III-V compound semiconductor layer and the second substrate are bonded together. When electrons or holes move across the bonding surface as in the case of direct bonding with a substrate, there is no problem that a potential barrier is formed that hinders the movement, thus hindering the operation of the semiconductor light emitting device. Absent.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 show a method for manufacturing a GaN-based semiconductor laser according to the first embodiment of the present invention. In the first embodiment, a resonator end face is defined by using a {2-1-10} plane of a GaN-based semiconductor as a cleavage plane,
That is, the case where the light emitting end face is formed will be described.

In the first embodiment, first, a C-plane sapphire substrate is placed in a reaction furnace of a metal organic chemical vapor deposition (MOCVD) apparatus, not shown, and then, for example, H is used as a carrier gas in the reaction furnace. ₂ flow, for example, 1050
By performing a heat treatment at 10 ° C. for 10 minutes, the surface of the C-plane sapphire substrate is cleaned. The thickness of the C-plane sapphire substrate is, for example, about 350 μm.

Next, after lowering the substrate temperature to, for example, 530 ° C., ammonia (NH ₃ ) as a N source and trimethylgallium (TMGa,
Ga (CH ₃ ) ₃ ) is supplied to grow an undoped GaN buffer layer (not shown) on a C-plane sapphire substrate having a cleaned surface. The thickness of the GaN buffer layer is, for example, 25 nm.

Next, as shown in FIG. 1, an n-type GaN contact layer 2, an n-type AlGaN cladding layer 3, and an undoped G
An aN active layer 4, a p-type AlGaN cladding layer 5, and a p-type GaN contact layer 6 are sequentially grown to form a laser structure. Specifically, first, the supply of TMGa into the reactor is stopped, and while the supply of NH ₃ is kept as it is, the growth temperature is raised to, for example, 1000 ° C., and then TMGa and n-type dopant are added into the reactor. Silane (SiH
₄ ) is supplied to grow the n-type GaN contact layer 2. Next, trimethyl aluminum (TMA) is placed in the reactor.
1, Al (CH ₃ ) ₃ ) to grow the n-type AlGaN cladding layer 3. Next, the supply of TMAl and SiH ₄ into the reactor is stopped, and the GaN active layer 4 is grown while the supply of TMGa and NH ₃ is maintained. Next, TMAl and cyclopentadienyl magnesium (Cp ₂ M
g) is supplied to grow the p-type AlGaN cladding layer 5. Next, the supply of TMAl into the reactor is stopped, and the p-type GaN contact layer 6 is grown.

Incidentally, as an example of the thickness of each layer, the n-type GaN contact layer 2 is 3 μm, and the n-type AlGaN cladding layer 3 and the p-type AlGaN cladding layer 5 are 0.5 μm.
m, the GaN active layer 4 is 0.05 μm, and the p-type GaN contact layer 6 is 1 μm. The Al composition ratio of the n-type AlGaN cladding layer 3 and the p-type AlGaN cladding layer 5 is, for example, 0.2. Further, the carrier concentration of the n-type GaN contact layer 2 and the n-type AlGaN cladding layer 3 is, for example, 3 × 10 ¹⁸ cm ⁻³ , and the carrier concentration of the p-type AlGaN cladding layer 5 and the p-type GaN contact layer 6 is, for example, 5 × 10 ¹⁷ cm ^-3 .

Here, the relationship of the crystal orientation between the C-plane sapphire substrate and the GaN-based semiconductor layer grown thereon will be clarified. FIG. 7 shows the crystal orientation relationship.

In FIG. 7, the direction of the orientation flat (OF) of the C-plane sapphire substrate is [11-2].
0] direction (referred to as “A direction”), and the (11-20) plane perpendicular to the A direction is referred to as A plane. The crystal axis of the GaN-based semiconductor layer on the C-plane sapphire substrate is rotated by 30 ° with respect to the crystal axis of the C-plane sapphire substrate. Therefore, the direction A of the C-plane sapphire substrate is [-11] for the GaN-based semiconductor layer on the C-plane sapphire substrate.
00] direction (referred to as “M direction”), and the (−1100) plane perpendicular to the M direction is referred to as M plane.

As a result of various experiments, the easy cleavage plane of the GaN-based semiconductor was (0001) plane (C plane) and Δ2-1-1
0｝ (A-plane), and the next easy to cleave is ｛-110
0 ° (M plane) was found (see FIG. 8). FIG.
2 shows the directions of the crack lines of the GaN-based semiconductor layer grown on the C-plane sapphire substrate. In this case, when cleaving is performed, cracks are first formed in the C-plane sapphire substrate, and then the GaN-based semiconductor layer is broken along the crack direction. Therefore, it is necessary to match the cleavage plane of the second substrate so as to match the M plane or the A plane of the GaN-based semiconductor layer.

After growing the p-type GaN contact layer 6 as described above, as shown in FIG.
A Ni / Au film 7 is formed on the aN contact layer 6 by a vacuum evaporation method or the like, and is brought into ohmic contact with the p-type GaN contact layer 6. Here, N in the Ni / Au film 7
The thicknesses of the i film and the Au film are, for example, 10 nm and 50 nm, respectively.

On the other hand, a p-type GaP substrate 8 having a (100) plane orientation as shown in FIG. 9 is separately prepared, and a Ni / Au / In film 9 is formed on the p-type GaP substrate 8 as shown in FIG. Is formed by a vacuum evaporation method or the like. The thicknesses of the Ni film, the Au film, and the In film in the Ni / Au / In film 9 are, for example, 10 nm, 50 nm, and 100 nm, respectively. Of the Ni / Au / In film 9, the Ni film and Au
The film is for making ohmic contact with the p-type GaP substrate 8, and the uppermost In film is for fusing with the Ni / Au film 7 formed on the p-type GaN contact layer 6. is there. The p-type GaP substrate 8 has a thickness of, for example, 300
μm.

Next, the Ni / Au / I of the p-type GaP substrate 8 was
The n film 9 side is on the Ni / Au film 7 side of the C-plane sapphire substrate 1, and the [0-1-1] direction, which is one of the easy cleavage directions (<110> direction), of the p-type GaP substrate 8 and GaN The semiconductor layers are aligned and superposed so that the [-1100] direction of the system semiconductor layers coincides with each other. This alignment is specifically performed as follows. That is, as shown in FIG. 9, the orientation flat of the p-type GaP substrate 8 is in the [0-1-1] direction. Therefore, by superimposing the C-plane sapphire substrate 1 and the p-type GaP substrate 8 so that the orientation flat of the C-plane sapphire substrate 1 and the orientation flat of the p-type GaP substrate 8 coincide with each other, the <0, which is the direction of easy cleavage
The <-1-1> direction and the <-1100> direction of the GaN-based semiconductor layer can be easily matched. Here, the accuracy of the positioning can be usually within ± 5 °.

Next, in a state where the p-type GaP substrate 8 and the C-plane sapphire substrate 1 are pressed, a heat treatment is performed at a temperature of 300 to 400 ° C. for 1 minute in an N ₂ gas atmosphere, for example.
Thus, as shown in FIG. 2, the Ni / Au film 7 on the C-plane sapphire substrate 1 and the Ni / Au film 7 on the p-type GaP substrate 8
The u / In film 9 is fused, and the C-plane sapphire substrate 1 and the p-type GaP substrate 8 are joined.

Next, the C-plane sapphire substrate 1 is wrapped from its back side by a lapping device (not shown) to reduce the thickness to, for example, 50 μm. Next, if necessary, the surface of the p-type GaP
After being covered with a protective film (not shown) such as a SiO ₂ film formed by the method D, the C-plane sapphire substrate 1 is etched using, for example, a 100 ° C. phosphoric acid aqueous solution. At this time, only the C-plane sapphire substrate 1 is removed by etching, and the GaN-based semiconductor layer and the p-type GaP substrate 8 are not etched. Thus, as shown in FIG. 3, the C-plane sapphire substrate 1 is completely removed.

Next, as shown in FIG. 4, the C-plane sapphire substrate 1 is etched away to remove the n-type G
An n-side electrode 10 is formed on the surface of the aN contact layer 2.
Specifically, the n-side electrode 10 has a thickness of, for example, 10n.
m, an Al film having a thickness of 10 nm and an Au film having a thickness of, for example, 200 nm are sequentially deposited to form Ti /
After forming the Al / Au film, the film is formed by performing a heat treatment at 600 ° C. for 1 minute in an N ₂ gas atmosphere. On the other hand, a p-side electrode 11 is formed on the back surface of the p-type GaP substrate 8 and brought into ohmic contact. As the p-side electrode 11, for example, a Ti / Pt / Au film is used.

Next, as shown in FIG. 5, a part of the n-side electrode 10 and the n-type GaN contact layer 2 is cut with, for example, a diamond pen so as to be cleaved in parallel with the orientation flat of the p-type GaP substrate 8. Scratched wound 12
Insert Next, with the n-side electrode 10 side down, a knife is applied perpendicularly to the orientation flat on the p-side electrode 11 immediately above the location where the scratch 12 has been made, and the p-type GaP
The substrate 8 is cleaved into a bar shape. At this time, the p-type GaP
As the substrate 8 is cleaved, the GaN-based semiconductor layer is also cleaved.
In this way, a cavity end face, that is, a light emission end face is formed. Thereafter, the bar is diced at predetermined intervals to form a chip, thereby forming a laser chip. As described above, as shown in FIG.
An N-based semiconductor laser is manufactured.

As described above, according to the first embodiment, the G laser for forming the laser structure on the C-plane sapphire substrate 1 is used.
An aN-based semiconductor layer is grown, and the uppermost p-type GaN contact layer 6 and the p-type GaP substrate 8 are joined via a Ni / Au film 7 and a Ni / Au / In film 9.
Cleavage direction of C type GaP substrate 8 and C-plane sapphire substrate 1
After making the cleavage direction of the upper GaN-based semiconductor layer coincide with that of the upper GaN-based semiconductor layer and removing the C-plane sapphire substrate 1 by lapping and etching from the back side thereof,
The GaN-based semiconductor layer is cleaved by cleaving the p-type GaP substrate 8 along the easy cleavage direction to form a cavity end face, that is, a light emission end face. Therefore, a GaN-based semiconductor laser can be manufactured at low cost without using an expensive substrate such as a SiC substrate. In addition, since the electrodes can be taken out from both the upper and lower surfaces, the process is simple and the face-down installation can be easily performed. Further, the p-type GaN contact layer 6 and the p-type GaP substrate 8 are formed of a multilayer metal film Ni / A
Since the p-type GaN contact layer 6 and the Ni / Au / In film 8 are joined via the
Since there is no potential barrier that prevents movement of electrons or holes between the semiconductor laser and the GaP substrate 8, the semiconductor laser can be operated without any trouble.

Next, a second embodiment of the present invention will be described. In the second embodiment, a case where the present invention is applied to the manufacture of a GaN-based semiconductor laser having a SCH (Separate Confinement Heterostructure) structure will be described.

In the second embodiment, as shown in FIG. 10, an n-type GaN buffer layer 22 is grown on a C-plane sapphire substrate 21 by a method similar to that of the first embodiment. On the n-type GaN buffer layer 22, an n-type GaN contact layer 23, an n-type AlGaN cladding layer 2
4, n-type GaN optical waveguide layer 25, active layer 26, p-type GaN
Optical waveguide layer 27, p-type AlGaN cladding layer 28, and p
The GaN contact layer 29 is sequentially grown. here,
As an example of the thickness of each layer, the n-type GaN buffer layer 22
Is 25 nm, the n-type GaN contact layer 23 is 3 μm, n
Type AlGaN cladding layer 24 is 0.5 μm, n-type GaN
The optical waveguide layer 25 is 0.1 μm, the p-type GaN optical waveguide layer 27 is 0.1 μm, and the p-type AlGaN cladding layer 28 is 0.5 μm.
The m, p type GaN contact layer 29 is 1 μm. The active layer 26 is made of, for example, Ga _0.8 In having a thickness of 2 nm.
It has a multiple quantum well structure in which _0.2 N layers and Ga _0.95 In _0.05 N layers each having a thickness of 4 nm are alternately stacked for 10 periods.

Next, as shown in FIGS. 10 and 11,
As in the first embodiment, the p-type GaN contact layer 29
Forming a Ni / Au film 30 thereon, bonding the p-type GaN contact layer 29 to the (100) plane p-type GaP substrate 31 via the Ni / Au film 30 and the Ni / Au / In film 32, After a process such as removal of the C-plane sapphire substrate 21, the p-type GaN contact layer 29 and the p-type AlGaN cladding layer are formed on the p-type GaP substrate 31 via the Ni / Au film 30 and the Ni / Au / In film 32. 28, p-type G
aN optical waveguide layer 27, active layer 26, n-type GaN optical waveguide layer 2
5. A structure is formed in which the n-type AlGaN cladding layer 24 and the n-type GaN contact layer 23 are sequentially laminated. Although illustration is omitted, in this case, on the p-type GaP substrate 31,
A semiconductor laser control circuit including a signal processing circuit, a high-frequency superimposing circuit, a power supply circuit, and a photodetection circuit is formed. The control circuit includes the Ni / Au film 30 and the Ni / A
The GaN semiconductor laser is connected via the u / In film 32.

Next, on the n-type GaN contact layer 23, for example, a 0.5 μm thick SiO ₂
After forming a film (not shown), the SiO ₂ film is lithographically formed, for example, with a thickness of 3.5 μm and a width of 10 μm.
An m-stripe resist pattern (not shown) is formed at a pitch of, for example, 400 μm, and the resist pattern is used as a mask to pattern the SiO ₂ film by wet etching using a hydrofluoric acid-based etchant. Next, using the stripe-shaped SiO ₂ film thus formed and the resist pattern thereon as a mask, for example, He is applied, for example, at an energy of 250 ke.
V ions are implanted under the conditions of a dose of 1 × 10 ¹⁵ cm ⁻² . At this time, the depth of the He peak concentration is about 2.5 μm.
Therefore, the n-type GaN contact layer 23 and the n-type A
He is ion-implanted into a part of the lGaN cladding layer 24 to increase the resistance. The high resistance region becomes the current confinement layer 33.

Next, the SiO ₂ film used as an etching mask is removed by wet etching using hydrofluoric acid, and the resist pattern thereon is also removed by lift-off. Next, an n-side electrode 34 is formed on the n-type GaN contact layer 23 and the current confinement layer 33, and a p-side electrode 35 is formed on the back surface of the p-type GaP substrate 31. Next, as in the first embodiment,
After making a scratch (not shown) on the surface on the n-side electrode 34 side, the p-type GaP substrate 31 and the G
By cleaving the aN-based semiconductor layer into a bar shape, a cavity end face, that is, a light emission end face is formed. Thereafter, the bar is divided into chips by dicing, for example, at an interval of 400 μm to form a laser chip. As described above, the intended GaN semiconductor laser having the SCH structure is manufactured.

According to the second embodiment, various advantages similar to those of the first embodiment can be obtained, and also the following advantages can be obtained. That is, in the GaN-based semiconductor laser, the current constriction on the n-layer side, which has not been considered before, has become possible, so that the p-side electrode 35 can be used as the entire surface electrode, and the contact resistance of the p-side electrode 35 is greatly increased. It is possible to achieve a significant reduction. Also,
P-type G in which the control circuit of the semiconductor laser is formed in advance
Since the aP substrate 31 is used, a GaN-based semiconductor laser in which a control circuit is formed on-chip can be realized.

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 idea of the present invention are possible.

For example, the numerical values, materials, raw material gases for growth, etc. listed in the above-described first and second embodiments are merely examples, and different numerical values, materials, raw material gases for growth, etc. may be used as necessary. May be used. In particular,
In the first and second embodiments described above, the Ni / A formed on the p-type GaN contact layer 6 is used.
u film 7 and Ni / Au /
The p-type GaN contact layer 6 and the p-type GaN
Type GaP substrate 8, for example, Ni / A
Instead of the u / In film 9, a Ni / Au film may be used.
In this case, compared with the case where the Ni / Au / In film 9 is used,
Although the easiness of fusion is reduced, fusion can be performed by performing a heat treatment at, for example, 300 to 400 ° C. for about 1 hour, and the p-type GaN contact layer 6 and the p-type GaP substrate 8 can be joined. It is possible. In the first and second embodiments, the C-plane sapphire substrate 1
Although 21 is used, a sapphire substrate having a different plane orientation may be used.

In the second embodiment described above,
The current confinement layer 33 is formed by implanting He ions into the n-type GaN contact layer 23 and the n-type AlGaN cladding layer 24. For example, the p-type GaN contact layer 29 and the p-type AlGaN
A current confinement layer may be formed in these layers by implanting He into the cladding layer 28. In this case, p
Considering that the thickness of the type GaN contact layer 29 is 1 μm, the energy of He ion implantation is set to, for example, 150 μm.
keV. The peak concentration depth at this time is about 1 μm.

In the second embodiment described above,
The current confinement layer 33 is formed by ion implantation. The current confinement layer 33 is formed, for example, in a portion corresponding to the current confinement layer 33 by the n-type GaN contact layer 23 and the p-type A
After the lGaN cladding layer 24 is removed by etching, it may be formed by embedding this portion with an insulating film. Further, the current confinement structure may be an internal confinement type or a buried heterostructure type.

In the first and second embodiments, the cleavage is performed after the C-plane sapphire substrates 1 and 21 are completely removed.
Cleavage may be carried out in a state where 1 is left with a thickness capable of being cleaved to form a cavity end face.

[0053]

As described above, according to the present invention, the nitride I grown on one main surface of the first substrate is used.
A group II-V compound semiconductor layer and a second substrate having a cleavage property are joined together via a conductive intermediate layer such as a metal film. At this time, the direction of easy cleavage of the second substrate and the nitride group III-V The first direction is set so that the easy cleavage direction of the compound semiconductor
The second substrate and the second substrate are aligned with each other;
After removing or thinning the substrate from the other main surface side,
Since the nitride-based III-V compound semiconductor layer is cleaved by cleaving the second substrate along the easy cleavage direction to form a light emitting end face, an expensive substrate such as a SiC substrate is used. Without using, nitride III-V
The light emitting end face of a semiconductor light emitting device using a group III compound semiconductor can be formed by cleavage, and electrodes can be taken out from both upper and lower surfaces, so that operation of the semiconductor light emitting device is not hindered.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a method for manufacturing a GaN-based semiconductor laser according to a first embodiment of the present invention.

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

FIG. 3 is a sectional view for explaining the method for manufacturing the GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view for explaining the method for manufacturing the GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 5 is a sectional view for explaining the method for manufacturing the GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 6 is a sectional view for explaining the method for manufacturing the GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 7: C-plane sapphire substrate and GaN grown on it
FIG. 3 is a schematic diagram illustrating a relationship between a crystal orientation and a system semiconductor layer.

FIG. 8 is a schematic diagram illustrating an easy cleavage surface of a GaN-based semiconductor.

FIG. 9 is a schematic diagram illustrating a (100) -oriented p-type GaP substrate used in the first embodiment of the present invention.

FIG. 10 is a cross-sectional view for explaining the method for manufacturing the GaN-based semiconductor laser according to the second embodiment of the present invention.

FIG. 11 is a perspective view for explaining the method for manufacturing the GaN-based semiconductor laser according to the second embodiment of the present invention.

FIG. 12 is an energy band diagram of a GaN / InP junction.

FIG. 13 is an energy band diagram of a p-type GaN / p-type InP junction.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... C-plane sapphire substrate, 2 ... n-type GaN contact layer, 7 ... Ni / Au film, 8 ... p-type GaP
Substrate, 9: Ni / Au / In film, 12: Scratches, 21: C-plane sapphire substrate, 23: n-type G
aN contact layer, 30 ... Ni / Au film, 31 ...
・ P-type GaP substrate, 32... Ni / Au / In film, 3
3 ... Current constriction layer

Claims (11)

[Claims] 1. A method for forming a light emitting end face of a semiconductor light emitting device using a nitride III-V compound semiconductor, comprising: forming a nitride III-V compound semiconductor layer constituting the semiconductor light emitting device on one of the main surfaces; The nitride-based III-V compound semiconductor layer of the first substrate grown on the surface is joined to one main surface of a second substrate having a cleavage via a conductive intermediate layer, In this case, the first substrate and the second substrate are aligned with each other such that the easy cleavage direction of the second substrate substantially matches the easy cleavage direction of the nitride III-V compound semiconductor layer. Removing the first substrate from the other main surface side or reducing the thickness thereof; and cleaving the second substrate along its easy cleavage direction to thereby form the nitride III-V compound. Cleaving the semiconductor layer to form a light emitting end face Forming a light emitting end face of the semiconductor light emitting device. 2. The method according to claim 1, wherein the second substrate is made of Si, Ge or II.
2. The method according to claim 1, wherein the substrate is a single crystal substrate made of an IV compound semiconductor. 3. The method according to claim 1, wherein the second substrate has conductivity. 4. The method according to claim 1, wherein the conductive intermediate layer comprises a metal film. 5. The method according to claim 1, wherein the conductive intermediate layer is formed of the nitride III.
10. A semiconductor device comprising: a first metal film formed in advance on a -V compound semiconductor layer; and a second metal film formed in advance on the one main surface of the second substrate. 2. The method for forming a light emitting end face of a semiconductor light emitting device according to claim 1. 6. The method according to claim 1, wherein the conductive intermediate layer is formed of the nitride III.
2. The light emitting end face of a semiconductor light emitting device according to claim 1, comprising a metal film formed in advance on one of the -V group compound semiconductor layer and the one main surface of the second substrate. Formation method. 7. The method according to claim 1, wherein the nitride III-V compound semiconductor layer is a growth layer having a (0001) plane orientation, and wherein the second substrate has a cubic crystal structure. The <1-100> direction or the <2-1-10> direction of the group V compound semiconductor layer and the <1
10. The light emitting end face of a semiconductor light emitting device according to claim 1, wherein said first substrate and said second substrate are aligned with each other so that the directions substantially coincide with each other. Method. 8. The [0001] direction of the nitride III-V compound semiconductor layer is parallel to the one main surface of the first substrate, and the second substrate has a cubic crystal structure. In the direction perpendicular to the [0001] direction of the nitride-based III-V compound semiconductor layer, <1-1
The first substrate and the second substrate are aligned with each other such that the <00> direction or the <2-1-10> direction substantially matches the <110> direction of the second substrate. 2. The method for forming a light emitting end face of a semiconductor light emitting device according to claim 1, wherein: 9. A vertical current confinement structure according to claim 1, wherein a current blocking layer is formed partially on said nitride III-V compound semiconductor layer. A method for forming a light emitting end face of a semiconductor light emitting device. 10. An ohmic or Schottky electrode is formed on the nitride-based III-V compound semiconductor layer after removing the first substrate. The method for forming a light emitting end face of a semiconductor light emitting device according to the above. 11. A control circuit for the semiconductor light emitting device is formed on the second substrate, and the control circuit is connected to the semiconductor light emitting device via the conductive intermediate layer. The method for forming a light emitting end face of a semiconductor light emitting device according to claim 1.