JP2001284721A - Semiconductor laser element and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser element and its manufacturing method that reduce a driving current and a driving voltage when output is high, and at the same time maintain excellent reliability for a long time. SOLUTION: In this semiconductor laser element that has a first conductive cladding layer, an active layer, a second conductive cladding layer with a ridge- shaped stripe, and a first conductive current constriction layer with the ridge- shaped stripe on a first conductive substrate, and also has a laser resonator that is formed in a ridge-shaped stripe direction, one main surface of the substrate is (100) surface, or is inclined from the surface (100), the oblique angle of the substrate in a region near the end face of the laser resonator is smaller than that of the internal region of the laser resonator, and the band gap of the active layer in the region near the end face of the laser resonator is larger than that of the active layer in the internal region of the laser resonator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device used for an optical disk or the like and a method of manufacturing the same, and more particularly to a window structure semiconductor laser device excellent in high output operation characteristics and a method of manufacturing the same. is there.

[0002]

2. Description of the Related Art In recent years, various semiconductor lasers have been widely used as light sources for optical disk devices. Above all,
The high-output 780 nm band AlGaAs semiconductor laser has an M
It is used as a light source for writing on discs such as D players and CD-R drives, and higher output is strongly required. One of the factors limiting the high output of the semiconductor laser is the optical damage (CO) caused by the increase in the optical output density in the active layer region near the laser cavity facet.
D: Catastrophic Optical Dam
age).

[0003] The cause of the above-mentioned COD is that the active layer region near the laser resonator end face is an absorption region for laser light. At the end face of the laser cavity, there are many non-radiative recombination centers called surface states or interface states. Since the carriers injected into the active layer near the laser resonator end face are lost by the non-radiative recombination, the injected carrier density of the active layer near the laser resonator end face is lower than that at the center. As a result, the active layer region near the end face of the laser resonator becomes an absorption region for the wavelength of the laser light generated by the high injected carrier density at the center.

As the light output density increases, local heat generation in the absorption region increases, the temperature rises, and the band gap energy decreases. As a result, a positive feedback that the absorption coefficient further increases and the temperature rises is applied, and the temperature of the absorption region near the end face of the laser resonator finally reaches the melting point, and COD occurs.

To improve the COD level, one method of increasing the output of a semiconductor laser is disclosed in JP-A-9-23.
No. 037, a method utilizing a window structure by disordering of a multiple quantum well structure active layer has been employed.

FIG. 14 shows a structure diagram of a semiconductor laser device disclosed in Japanese Patent Application Laid-Open No. 9-23037 as a prior art of a semiconductor laser having this window structure.

In FIG. 14, (a) is a perspective view including the end face of the laser resonator, and (b) is Ia-Ia 'in FIG. 14 (a).
14C is a cross-sectional view of the waveguide taken along the line, and FIG. 14C is a cross-sectional view in the layer thickness direction taken along the line Ib-Ib ′ of FIG. FIG.
4, 1001 is a GaAs substrate, 1002 is an n-type A
lGaAs lower cladding layer, 1003 is a quantum well active layer,
1004a is a p-type AlGaAs first upper cladding layer;
4b is a p-type AlGaAs second upper cladding layer, 1005 is a p-type GaAs contact layer, 1006 (shaded portion) is a hole diffusion region, 1007 (shaded portion) is a proton injection region, 100
Reference numeral 8 denotes an n-side electrode, 1009 denotes a p-side electrode, 1020 laser resonator end face, 1003a denotes a region contributing to laser oscillation of the quantum well active layer 1003, and 1003b denotes a quantum well active layer 1
003 is a window structure area formed in the vicinity of the laser cavity end face 1020.

Next, a conventional method for manufacturing a semiconductor laser device will be described with reference to a process chart shown in FIG.

On an n-type GaAs substrate 1001, an n-type AlG
aAs lower cladding layer 1002, quantum well active layer 100
3. The p-type AlGaAs first upper cladding layer 1004a is sequentially epitaxially grown (FIG. 15A). Next, p-type A
SiO _{2 is} formed on the surface of the first upper cladding layer 1004a of lGaAs.
A film 1010 is formed, and a stripe-shaped opening 1 extending in the laser resonator direction with a length not reaching the laser resonator end face.
010a is formed (FIG. 15B). Next, when this wafer is annealed in an As atmosphere at a temperature of 800 ° C. or higher, Ga atoms are sucked up from the surface of the p-type AlGaAs first upper cladding layer 1004a in contact with the SiO ₂ film 1010, and p
Vacancies are formed in the first AlGaAs first upper cladding layer 1004a, and the vacancies are formed in the quantum well layer active layer 10 inside the crystal.
03 until the quantum well layer structure is disordered. In the disordered active layer region, the effective band gap widens, so that it functions as a window transparent to the oscillating laser light.

Further, the SiO ₂ film 1010 is removed, and p
P-type AlGaAs on the first upper cladding layer 1004a
A GaAs second upper cladding layer 1004b and a p-type GaAs contact layer 1005 are sequentially grown epitaxially.
(FIG. 15 (c)). Next, the p-type GaAs contact layer 10
A resist film is formed on the 05, the resist 1 in stripes same region as the opening 1010a of the stripe of the SiO ₂ film 1010 by photolithography
011 is formed. Next, this striped resist 1
011 as a mask, p-type GaAs contact layer 100
5 is implanted from the surface side to form a high-resistance region 1007 to be a current blocking layer. (FIG. 15
(D)). Finally, the n-side electrode 1 is placed on the GaAs substrate 1001 side.
008, a p-side electrode 1009 is formed on the p-type GaAs contact layer 1005, and the wafer is cleaved to obtain the semiconductor laser device of FIG.

[0011]

THE INVENTION Problems to be Solved] disordered region formed in the vicinity of the laser resonator end face of a conventional window structure semiconductor laser device, so as to be larger than the band gap energy corresponding to the lasing wavelength, SiO ₂ film It is formed by generating Ga vacancies in the p-type AlGaAs first upper cladding layer 1004a in contact with 1010 and diffusing Ga vacancies into the quantum well layer active layer 1003. The generation and diffusion of the Ga vacancies are performed by annealing at 800 ° C. or higher, but annealing at 800 ° C. or higher diffuses not only Ga vacancies but also other impurity atoms. In particular, impurity atoms having a large diffusion coefficient show a remarkable diffusion phenomenon.

In general, p-type conductive impurities such as Zn, Mg and Be atoms having a large diffusion coefficient are used as p-type conductive impurities in each of the epitaxially grown layers. Also, the p-type conductive impurity diffuses into the quantum well layer active layer 1003 in large quantities.

As a result, the driving current and the driving voltage at the time of high output increase, and the long-term reliability decreases.

If the annealing temperature is lowered or the annealing time is shortened, the quantum well layer active layer 10
03 can suppress the diffusion of impurities such as Zn atoms, but the generation of vacancy atoms and the diffusion of vacancy atoms into the quantum well layer active layer 1003 become insufficient. Absorb.

As a result, COD is likely to occur in the active layer region near the laser cavity end face, causing a decrease in the maximum optical output during high-output driving, and failing to provide sufficient long-term reliability.

An object of the present invention is to provide a semiconductor laser device which reduces the driving current and the driving voltage at the time of high output and is excellent in long-term reliability, and a method of manufacturing the same, as a result of studying the above problems. Is what you do.

[0017]

A semiconductor laser device according to the present invention comprises a first conductive type clad layer, an active layer, a second conductive type clad layer having a ridge-shaped stripe on a first conductive type substrate, A first ridge-shaped stripe opening
In a semiconductor laser device including a conduction type current confinement layer and a laser resonator formed in the ridge-shaped stripe direction, one main surface of the substrate is a (100) plane or (10).
0), the inclination angle of the substrate in the region near the end face of the laser resonator is smaller than the internal area of the laser resonator, and the active layer in the region near the end face of the laser resonator. Is achieved by making the band gap of the active layer larger than the band gap of the active layer in the internal region of the laser resonator.

In the semiconductor laser device according to the present invention, the above object is attained by the fact that the substrate inclining direction is the same in the region near the laser cavity end face and in the region inside the laser cavity.

In the semiconductor laser device according to the present invention, one principal surface of the substrate in the region near the laser cavity end face and in the region inside the laser cavity is oriented in the [0-11] direction or the [01-] direction from the (100) plane. 1] and the ridge stripe direction is the [011] direction or the [0-1] direction.
The above object is achieved by being in the [-1] direction.

In the semiconductor laser device according to the present invention, one principal surface of the substrate in the region near the laser cavity end face and in the region inside the laser cavity is oriented in the [011] direction or the [0-1-] direction from the (100) plane. 1] and the ridge stripe direction is in the [0-11] direction or in the [01] direction.
The above object is achieved by being in the [-1] direction.

In the semiconductor laser device according to the present invention, the tilt angle of the substrate in the region near the end face of the laser resonator is 0 ° or more and less than 5 °, and the tilt angle of the substrate in the internal region of the laser resonator is 5 ° or more. The above object is achieved by being 15 degrees or less.

In the semiconductor laser device according to the present invention, the second conductivity type cladding layer has a carrier concentration lower in a region near the end face of the laser resonator than in a region inside the laser resonator. Achieve the goal.

In the method of manufacturing a semiconductor laser device according to the present invention, when manufacturing the above-described semiconductor laser device, one principal surface of the substrate is inclined from the (100) plane, and the inclination angle is
A processing step of processing to be smaller in an area near the laser resonator end face than in the laser resonator inner area, and at least a first conductivity type cladding layer and an active layer on the first conductivity type substrate processed by the processing step Forming a second conductive type cladding layer and a second conductive type protective layer in sequence, and selectively forming a dielectric film on the second conductive type protective layer; and forming the dielectric film and the epitaxial growth. Annealing the layer and the substrate, wherein the annealing step generates holes under the dielectric film and diffuses the holes until reaching the active layer. The above object is achieved by making the band gap in the region near the laser cavity end face larger than the band gap in the region inside the laser cavity.

In the method of manufacturing a semiconductor laser device according to the present invention, in the processing step, a substrate inclined within a range of 0 degree or more and less than 5 degrees from a (100) plane is used in a region inside a laser resonator. One main surface of the substrate from (100) plane
The above-mentioned object is achieved by processing to be inclined within a range of 5 degrees or more and 15 degrees or less.

In the method of manufacturing a semiconductor laser device according to the present invention, in the processing step, a substrate which is inclined within a range of 5 degrees or more and 15 degrees or less from a (100) plane may be used in a region near an end face of a laser resonator. The above object is achieved by processing such that one principal surface of the substrate in (1) is inclined from the (100) plane within a range of 0 degree or more and less than 5 degrees.

In the method of manufacturing a semiconductor laser device according to the present invention, the processing step includes a step of forming a resist mask selectively inclined on the substrate, and a step of isotropically etching the resist mask and the substrate. By achieving the above, the above object is achieved.

As the form of the active layer of the present invention, a well-known form may be used. In the case where the active layer is formed by sandwiching a multi-quantum well structure in which barrier layers and well layers are alternately stacked between optical guide layers. More effective.

Hereinafter, the operation of the present invention will be described.

In the semiconductor laser device and the method of manufacturing the same according to the present invention, one principal surface of the first conductivity type substrate in the region near the laser cavity end face and in the region inside the laser cavity is inclined from (100). Since the inclination angle of the first conductivity type substrate in the region near the laser cavity end face is smaller than the region inside the laser cavity, impurity atoms such as Zn present in each layer epitaxially grown on the first conductivity type substrate are not included in the substrate. The activation rate as a carrier is lower than that of impurity atoms such as Zn present in each layer epitaxially grown on the first conductivity type substrate whose main surface is (100). Even if an annealing step is performed to make the band gap of the active layer in the laser cavity inner region larger than that of the active layer, the heat energy given by the annealing Since used to improve the activation rate of impurity atoms, hardly used in the diffusion of the impurity atoms. Therefore, the second cladding layer of the second conductivity type and the third cladding of the second conductivity type in the laser cavity inner region epitaxially grown on the substrate of the first conductivity type in which one main surface of the substrate is inclined from (100). Diffusion of impurity atoms such as Zn existing in the layer into the active layer can be suppressed. Further, one main surface of the first conductivity type substrate in the region near the laser resonator end face and the area inside the laser resonator is inclined from (100), and the first conductivity type substrate in the area near the laser resonator end face (100) is tilted. Processed so that the angle of inclination from the surface is smaller than the laser cavity inner area, and the first conductive type first cladding layer, barrier layer and well layer are alternately laminated on the processed first conductive type substrate. Active layer, the second conductive type second clad layer, the second conductive type etching stop layer, the second conductive type third clad layer, the second conductive type Are sequentially grown epitaxially, a dielectric film is formed on the surface of the epitaxially grown wafer in the region near the laser cavity facet, and the dielectric film and each layer formed by the epitaxial growth are annealed. Therefore, Ga atoms and the like are absorbed into the dielectric film from the surface of the epitaxially grown wafer immediately below the dielectric film, and vacancy is generated inside the epitaxially grown wafer, and the diffusion of the vacancy is inhibited. Without being
Since the diffusion of vacancy atoms can be promoted, a sufficient amount of vacancy atoms diffuses in the direction of the substrate, and the band gap of the active layer near the laser cavity end face is reduced by the activation of the laser cavity internal region. It is possible to make the window region larger than the band gap of the layer, and it is possible to make the window region free of laser light absorption.

[0030]

Embodiments of the present invention will be described below in detail. (Embodiment 1) FIG. 1 is a sectional view showing the structure of a semiconductor laser device of Embodiment 1. 1A is a perspective view including a light emitting end face, FIG. 1B is a cross-sectional view of a waveguide taken along the line Ia-Ia ′ in FIG. 1A, and FIG.
It is sectional drawing in the layer thickness direction in Ib 'line. Also, 10
In 1, one main surface of the laser resonator inner region is inclined at 10 degrees from the (100) to the [01-1] direction, and one main surface near the laser resonator end surface is (100) to [01-1]. N-type GaAs substrate tilted twice in the direction, 102 is an n-type AlGaAs first cladding layer, 103 is an active layer having a multi-quantum well structure in which barrier layers and well layers are alternately stacked and sandwiched by an optical guide layer. (MQW active layer), 104 is a p-type AlGaAs second cladding layer, 105 is a p-type etching stop layer, 106 is a p-type AlGaAs third cladding layer formed of a ridge stripe in the resonator direction, 107 is a p-type GaAs protection layer, 108 is a ridge stripe p
N-type AlGaAs current blocking layer formed so as to bury the side surface of the third type AlGaAs third cladding layer;
Type GaAs planarization layer, 110 is a p-type GaAs contact layer, 111 is a p-side electrode, and 112 is an n-side electrode. Reference numeral 113 denotes a region where the bandgap energy of the MQW active layer near the laser resonator end face is larger than the bandgap energy of the MQW active layer 103 inside the laser resonator (window region). Reference numeral 114 denotes a region on the p-type GaAs protective layer 107. A current non-injection region formed by the formed n-type AlGaAs current blocking layer 108a and the p-type GaAs planarization layer 109a, and a stripe-shaped ridge 115 formed by the p-type AlGaAs third cladding layer 106 and the p-type GaAs protection layer 107. .

Next, a manufacturing method will be described with reference to FIG.

One main surface of the substrate is changed from (100) to [01-
1] A resist is applied on the surface of the n-type GaAs substrate 100 inclined at 2 degrees in the direction of 0.2 μm in thickness and has a distribution of ± 2% or less, prebaked, and then exposed using an exposure apparatus. To perform patterning.

The photomask used at this time is shown in FIG.
As shown in (a), a striped halftone light blocking pattern and a striped full blocking pattern are periodically repeated, and the length of the cycle is equal to the laser cavity length of the semiconductor laser device of the present invention. And photomasks (I) and (II).

The halftone light shielding pattern of the photomask (I) is designed so that the light transmittance is constant in the stripe direction.

In the halftone light shielding pattern of the photomask (II), the light transmittance changes in a gradient direction in the stripe direction, and the light transmittance gradient is periodically repeated. As shown in FIG. 3B, the length of the period is equal to the chip width of the semiconductor laser device of the present invention, and the light transmittance at the center of the period is half-tone light shielding of the photomask (I). It is designed to be equal to the light transmittance of the pattern. In the present embodiment, the photomask (II) having a halftone pattern with a relative change of the light transmittance gradient of ± 20% from the center of the period as shown in FIG. 3C was used.

The halftone pattern of the photomask (II) is obtained by using Cr as a mask material for the halftone portion.
_{x O y N z, Mo w} Si x O y N z, Si x N y (w, x, y,
(z is 1 or more), and the like, and can be produced by gradiently changing the deposition rate or composition at the time of vapor deposition of the mask material on the glass substrate.

In patterning using an exposure apparatus, first, one main surface of the substrate is (100) using a photomask (I).
N-type GaAs that is tilted twice in the [01-1] direction from
Alignment is performed so that the [01-1] direction of the substrate 100 and the stripe direction of the halftone pattern coincide with each other, the amount of energy exposure to be irradiated is adjusted, and the resist is exposed only at a certain depth from the surface. Next, using the photomask (II), alignment is performed so that the halftone pattern of the photomask (I) previously exposed is covered by the entire shielding pattern of the photomask (II). The resist mask is exposed only at a certain depth from the surface with the same energy exposure amount as that described above. The portion patterned using the photomask (I) is shown in FIG.
1 corresponds to the region near the laser resonator end face, and the portion patterned using the photomask (II) corresponds to the laser resonator internal region 101 shown in FIG.

In the resist exposed in this manner, the cross-linking depth of the photosensitive molecules in the resist changes along the periodic light transmittance gradient in each photomask in the region of the halftone pattern. By performing known processing such as development and baking, a resist mask 116 shown in FIG. 2A is formed.

The region of the resist mask 116 near the laser resonator end face has a width of 40 μm extending in the [01-1] direction.
And the stripe pitch is 800 μm, which is the same as the laser cavity length. The region inside the laser resonator of the resist mask 116 has a film thickness distribution in which the film thickness is inclined in the [01-1] direction. The film thickness is the same as the film thickness in the region near the laser resonator end face.

Thereafter, using a dry etching technique,
Etching is performed until the resist mask 116 formed on the surface of the n-type GaAs substrate 100 in which one main surface of the substrate is tilted twice from the (100) in the [01-1] direction is removed, and FIG. ) Is processed into an n-type GaAs substrate 101.

N-type GaAs obtained by the above processing method
As a result of measuring the s-substrate 101 with a scanning electron microscope (SEM), one principal surface near the laser resonator end face was (10
0) is a surface inclined two degrees in the [01-1] direction, and one main surface of the laser cavity internal region is a surface inclined 10 degrees in the [01-1] direction from the (100). Was.

From this, one main surface of the n-type GaAs substrate in the region near the laser resonator end face and the main surface in the laser resonator inner area are inclined in the same direction from (100), and the n-type GaAs substrate near the laser resonator facet is in the same direction. It is clear that the inclination angle of the GaAs substrate can be processed to be smaller than the laser cavity internal region. Also, a resist mask is formed on an n-type GaAs substrate, and the n-type GaAs is removed until the resist mask is removed.
It is clear that by dry-etching the As substrate, the n-type GaAs substrate can be easily processed into various shapes simply by changing the shape of the resist mask.

Next, processed by the above manufacturing method,
One main surface of the laser cavity internal region is changed from (100) to [01].
-1] direction, and one principal surface in the vicinity of the laser cavity end face is 2 degrees from (100) in the [01-1] direction.
A multi-quantum well structure in which an n-type AlGaAs first cladding layer 102, a barrier layer, and a well layer are alternately stacked on an n-type GaAs substrate 101 inclined at a predetermined angle in order by a metal organic chemical vapor deposition (MOCVD) method. An active layer (MQW active layer) 103 sandwiched between light guide layers, a p-type AlGaAs second cladding layer 104, a p-type etching stop layer 105,
The third AlGaAs third cladding layer 106 and the p-type GaAs protective layer 107 are epitaxially grown (FIG. 2).
(C)).

Thereafter, the p-type GaAs protective layer 107 in the region near the laser resonator end face where one main surface of the n-type GaAs substrate 101 is tilted twice from (100) in the [01-1] direction.
The width of 40 μm in the direction perpendicular to the ridge stripe was formed on the surface of the substrate by plasma CVD and photolithography.
An m-shaped striped dielectric film 117 is formed. In addition,
In this embodiment, Si _x O _{y (x} as a dielectric film 117, y
1 or more) film, and the pitch of the stripe was 800 μm, which is the same as the resonator length (FIG. 2D).

Next, rapid thermal annealing (RT
Annealing by the method A) results in a dielectric film of Si _x
The band gap energy of the MQW active layer (window region) 113 immediately below the O _y (x, y is 1 or more) film 117 is made larger than the band gap energy of the MQW active layer (active region) 103 in the laser cavity internal region.

Using a part of the wafer annealed by the RTA method, a photoluminescence (PL) method is used.
The respective wavelengths of the MQW active layer (window region) 113 immediately below the Si _x O _y (x, y is 1 or more) film 117 and the MQW active layer (active region) 103 inside the laser cavity are measured. did.

As a result, one main surface of the laser cavity inner region is inclined by 10 degrees in the [01-1] direction from (100), and one main surface near the laser cavity end surface is changed from (100) to [01-1]. 01-1] the wafer obtained by the manufacturing method of the present invention using the n-type GaAs substrate 101 inclined 2 ° in the direction, a dielectric film Si _x O _{y (x, y} is 1 or more)
The emission spectrum from the MQW active layer 113 immediately below the film 117 was shifted by 30 nm to a shorter wavelength side than the emission spectrum from the MQW active layer 103 in the laser cavity inner region.

From this, one main surface of the n-type GaAs substrate in the region near the laser cavity facet and the main surface of the n-type GaAs substrate in the region inside the laser cavity are inclined in the same direction from (100), and in the region near the laser cavity facet. A semiconductor laser device in which the tilt angle of the n-type GaAs substrate is smaller than the laser cavity internal region and the band gap of the active layer in the region near the laser cavity end face is larger than the band gap of the active layer in the laser cavity internal region. It is clear that

Further, using a part of the wafer after the annealing, one main surface of the n-type GaAs substrate 101 is tilted twice from (100) to [01-1] direction by CV method. P-type AlGaAs in the region near the laser cavity facet
The carrier concentration of the three cladding layers 104 and 106 and the n-type G
One main surface of the aAs substrate 101 is changed from (100) to [01-
The carrier concentration of the p-type AlGaAs second and third cladding layers 104 and 106 in the laser resonator inner region inclined by 10 degrees in the [1] direction was measured.

As a result, the carrier of the p-type AlGaAs second cladding layer 104 in the vicinity of the laser resonator end face where one main surface of the n-type GaAs substrate 101 is tilted twice from the (100) in the [01-1] direction. The concentration is n-type GaAs substrate 1
01 is 10 from (100) in the [01-1] direction.
AlGaAs in the laser cavity inner region inclined at an angle
The concentration was lower than the carrier concentration of the second cladding layer 104. Also, one main surface of the n-type GaAs substrate 101 is (10
0) The p-type AlGaAs third cladding layer 1 in the region near the end face of the laser resonator that is inclined by 2 degrees in the [01-1] direction
The carrier concentration of 06 is the carrier concentration of the p-type AlGaAs third cladding layer 106 in the laser resonator inner region where one main surface of the n-type GaAs substrate 101 is inclined by 10 degrees from the (100) in the [01-1] direction. Lower concentrations.

Therefore, the p-type AlGaAs second cladding layer 104 and the p-type AlGaAs third cladding layer 10
It is apparent that a semiconductor laser device having a lower carrier concentration in the region near the laser cavity end face than in the region inside the laser cavity is obtained.

Next, the Si _x O _y (x, y is 1 or more) film 117, which is the dielectric film formed in the region near the end face of the laser cavity, is removed, and the film is removed using a known photolithography technique. A resist mask 118 having a stripe shape extending in the [011] or [0-1-1] direction is formed on the type GaAs protective layer 107, and a known etching technique is used.
The p-type GaAs protective layer 107 and the p-type AlGaAs third cladding layer 106 are extended in the [011] or [0-1-1] direction into a stripe-shaped ridge having a width of about 3 μm so as to reach the p-type etching stop layer 105. It is processed into 115 (FIG. 2E).

Thereafter, the striped resist mask 118 formed on the p-type GaAs protective layer 107 is removed, and the p-type GaAs protective layer 107 and the p-type AlGaAs third cladding layer 106 are formed by the second MOCVD method. The side surfaces of the ridge 115 are buried with an n-type AlGaAs current block layer 108 and a p-type GaAs planarization layer 109 (FIG. 2F).

Next, the p-type GaAs planarization layer 109 formed on the side surface of the ridge 115 and the p-type GaAs planarization layer 109 formed on the ridge 115 having a width of 40 μm are formed by using a known photolithography technique. A resist mask 119 is formed in a region near the end face of the laser resonator having a stripe shape, and the n-type AlGaAs current blocking layer 108 at the opening of the resist mask 119 is formed by using a known etching technique.
And the p-type GaAs planarization layer 109 is selectively removed (FIG. 2G).

Using a part of the wafer, a laser in which one main surface of the n-type GaAs substrate 101 is tilted twice from (100) to [01-1] direction by a scanning electron microscope (SEM). Resonator end face vicinity region and n-type GaAs substrate 1
01 is 10 from (100) in the [01-1] direction.
The cross section of the wafer in the laser resonator inner region inclined at an angle was measured.

As a result, a current non-injection region is formed on the ridge 115 near the laser resonator end surface where one main surface of the n-type GaAs substrate 101 is tilted twice from (100) in the [01-1] direction. A laser in which an n-type AlGaAs current block layer 108a and a p-type GaAs planarization layer 109a to be 114 exist, and one main surface of the n-type GaAs substrate 101 is inclined by 10 degrees from (100) to [01-1] direction. The n-type AlGaAs current blocking layer 108 and the p-type GaAs planarization layer 109 did not exist at all on the ridge 115 in the resonator internal region.

As a result, the current non-injection region 114 is formed in the region near the laser resonator end surface where one main surface of the n-type GaAs substrate 101 is tilted twice from (100) in the [01-1] direction by the above process. Formed on the ridge 115;
One main surface of the n-type GaAs substrate 101 changes from (100) to [0
[1-1] The n-type AlGaAs current blocking layer 108 and the p-type GaAs planarization layer 109 formed on the ridge 115 in the laser resonator inner region inclined by 10 degrees in the direction can be selectively removed. it is obvious.

In the formation of the current non-injection region by the above process, one main surface of the n-type GaAs substrate in the region near the laser cavity end face and in the region inside the laser cavity is (10).
A semiconductor which is a surface inclined from 0) to the [0-11] or [01-1] direction, and the direction in which the ridge-shaped stripe is formed is the [011] or [0-1-1] direction. In the case of a laser device, the n-type AlGaAs current formed on the ridge 115 in the laser resonator inner region in which one main surface of the n-type GaAs substrate 101 is inclined by 10 degrees from (100) in the [01-1] direction. Block layer 108 and p-type GaAs
This is particularly preferable because the flattening layer 109 hardly remains.

Thereafter, the resist mask 119 formed on the p-type GaAs planarization layer 109 is removed, and the third M
The p-type GaAs contact layer 110 is formed by the OCVD method (FIG. 2H). Further, a p-electrode 111 is formed on the upper surface, and an n-electrode 112 is formed on the lower surface.

Next, a scribe line is inserted substantially at the center of the region near the end face of the laser resonator having a width of 40 μm, and the laser is divided into bars in the length of the resonator.

Thus, one main surface of the n-type GaAs substrate 101 in the region near the laser cavity end face and in the region inside the laser cavity is changed from (100) to [01-1] or [0-11].
Since the ridge-shaped stripe is formed in the [011] or [0-1-1] direction, the light emission direction is [011] or [01].
It is possible to form a resonator in a direction perpendicular to the -1-1] direction.

Finally, a light-reflecting film is coated on the light emitting end faces on both sides of the bar and further divided so as to have an arbitrary chip width, and a window area of about 20 μm is formed on the laser resonator end face of the 800 μm long resonator. And an element having a current non-injection region is manufactured.

In the semiconductor laser device of the present invention obtained by the above-described manufacturing method, one main surface of the n-type GaAs substrate 101 is formed in the laser resonator inner region where the main surface is inclined by 10 degrees in the [01-1] direction from (100). The distribution of Zn atoms in the depth direction before and after annealing was measured by a secondary ion mass spectrometer (SIMS). FIG. 4 shows the results.

For comparison, in the above-described semiconductor laser device of the present invention, one main surface of the substrate in the laser resonator internal region and the region near the laser resonator end face is shifted from the (100) plane to the [01-1] plane. The depth direction distribution of Zn atoms before and after annealing in the laser resonator internal region of the conventional semiconductor laser device, which was obtained by changing to an n-type GaAs substrate inclined two degrees in the direction, was measured by a SIMS apparatus. Figure 5 shows the results.
Shown in

The vertical axes in FIGS. 4 and 5 indicate the impurity atom concentration (at
oms / cm ³ ), and the horizontal axis is the depth (μm) from the p-type GaAs protective layer. 4 and 5, the broken lines indicate the distribution of Zn atoms in the depth direction before annealing, and the solid lines indicate the distribution in the depth direction after annealing.

As can be seen from FIGS. 4 and 5, one principal surface of the substrate in the laser cavity inner region and the region near the laser cavity end surface is inclined by two degrees from the (100) plane to the [01-1] direction. In the laser cavity inside region of a conventional semiconductor laser device obtained by changing to an n-type GaAs substrate, after annealing, the Zn atom concentration of each layer exhibiting p-type conductivity is reduced, and the n-type The diffusion of Zn atoms to the AlGaAs first cladding layer side is observed. However, one main surface of the n-type GaAs substrate 101 of the semiconductor laser device of the present invention is (10
0) in the laser resonator inner region inclined 10 degrees in the [01-1] direction from the n-type Al
The diffusion of Zn atoms to the GaAs first cladding layer 102 side and the decrease in Zn atom concentration in each of the layers 104 to 107 exhibiting p-type conductivity are not observed.

From this, one principal surface of the substrate in the laser cavity internal region is shifted from (100) by 10 in the [01-1] direction.
It is apparent that the use of the n-type GaAs substrate 101 inclined at a low degree can suppress the diffusion of Zn atoms to the n-type AlGaAs first cladding layer side.

The characteristics of the semiconductor laser device obtained by the above-described manufacturing method of the present invention were measured.

For comparison, the inclination angle from the (100) plane of the n-type GaAs substrate to the [01-1] direction in the laser cavity inner region and the region near the laser cavity end face is both 2 degrees. The characteristics of a conventional semiconductor laser device obtained by changing to an n-type GaAs substrate were also measured.

As a result, the oscillation wavelength (λ) at a CW of 120 mW was 785 nm for both the semiconductor laser device of the present invention and the prior art, and the CW of 120 mW for the semiconductor laser device of the present invention.
The driving current (Iop) at 150 W is 150 mA, and the driving current (Io) at 120 W of CW of the conventional semiconductor laser device is
p) is 210 mA, CW1 of the semiconductor laser device of the present invention.
The driving voltage (Vop) at 20 mW is 2.0 V, and the driving voltage (Vop) at a CW of 120 mW of the conventional semiconductor laser device is
op) is 2.4 V, and it is clear that in the method for manufacturing a semiconductor laser device of the present invention, a lower drive current and a lower drive voltage are realized. The lowering of the driving current and the lowering of the driving voltage are the effects of reducing the diffusion of Zn atoms into the MQW active layer 103 in the laser cavity internal region.

When these semiconductors were subjected to a reliability test at 70 ° C. and 120 mW, the average life of the conventional semiconductor laser device was 300 hours or less, whereas the average life of the semiconductor laser device of the present invention was approximately 3000 hours. The average life was improved more than 10 times.

In the semiconductor laser device of the present invention, the carrier concentration near the laser resonator end face is lower than that in the laser resonator inner region, and the active region 103 and the window region 1
As a result, the window region 113 of the laser beam formed in the active region 103 is increased.
This is because the absorption in

In this embodiment, the n-type GaAs substrate in which the main surface inside the laser cavity and one main surface in the region near the end face of the laser cavity is inclined in the [01-1] direction from (100). The same effect as described above can be obtained even with an n-type GaAs substrate in which one main surface of the cavity internal region and the region near the end face of the laser cavity is inclined from (100) in the [0-11] direction.

In the present embodiment, the dielectric film of Si _x O
_y (x, y is 1 or more), but the film 117 is formed using a plasma CVD method, even by using a sputtering method, Si _x O
At the time of forming a _y (x, y is 1 or more) film, vacancy atoms are generated by plasma damage on the surface of the epitaxially grown wafer, and the active layer in the vicinity of the laser cavity end face is effectively removed from the laser cavity internal region. Active layer (active area)
Because a window region with a wide bandgap can be formed more effectively,
The same effects as above can be obtained.

[0075] In the present embodiment, Si _x O as a dielectric film
_y (x, y is 1 or more) was used _{film, Si x N y, Si x} O
If _{y N z (x, y,} z is 1 or more) either it can be holes atoms to produce a p-type GaAs protective layer 107 of the lower dielectric layer 117, effectively laser resonator end face Since a window region having a wider bandgap can be effectively formed in the active layer in the vicinity region than in the active layer (active region) in the laser cavity inner region, the same effect as described above can be obtained.

In this embodiment, the length of the region in the vicinity of the end face of the laser resonator is 20 μm, but the same effect can be obtained as long as the length is in the range of 10 μm to 60 μm.

Although the present embodiment has been described with reference to an AlGaAs-based semiconductor laser, similar effects can be obtained with an AlGaInP-based semiconductor laser. (Embodiment 2) FIG. 6 is a sectional view showing a structure of a semiconductor laser device of Embodiment 2. 6, (a) is a perspective view including the light emitting end face, (b) is a cross-sectional view of the waveguide taken along the line Ia-Ia 'in FIG. 6 (a), and (c) is Ib- in FIG. 6 (a). I
It is sectional drawing of the layer thickness direction in the b 'line. Also, 201
Indicates that one principal surface of the laser cavity internal region is (100) to [0
11], an n-type GaAs substrate in which one main surface in the vicinity of the end face of the laser cavity is the (100) plane, 202 is an n-type AlGaAs first cladding layer, 203 is an MQW active layer, 204 Is a p-type AlGaAs second cladding layer, 205 is a p-type etching stop layer, 206 is a p-type AlGaAs third cladding layer composed of a ridge stripe in the resonator direction, 207 is a p-type GaAs protective layer, and 208 is a p-type ridge stripe. N-type AlGaAs formed so as to bury the side surface of the third type AlGaAs third cladding layer
A current blocking layer 209 is a p-type GaAs planarization layer, 21
0 is a p-type GaAs contact layer, 211 is a p-side electrode, 2
Reference numeral 12 denotes an n-side electrode. Reference numeral 213 denotes a region where the bandgap energy of the MQW active layer in the vicinity of the laser resonator end face is larger than the bandgap energy of the MQW active layer 203 inside the laser resonator (window region), and 214 denotes a region on the p-type GaAs protective layer 207. N-type AlGaAs formed
Current block layer 208a and p-type GaAs planarization layer 209
a, a current non-injection region 215 is a p-type AlGaAs
This is a stripe-shaped ridge composed of the third cladding layer 206 and the p-type GaAs protective layer 207.

Next, a manufacturing method will be described with reference to FIG.

One main surface of the substrate is changed from (1 0 0) to [0 1
N-type GaAs substrate 200 tilted 10 degrees in [1] direction
A resist is applied on the surface of the substrate so as to have a thickness of 0.2 μm and a distribution within ± 2%, and after prebaking, patterning is performed using an exposure apparatus.

The photomask used at this time is shown in FIG.
As shown in (a), two types of stripe-like halftone light shielding patterns (α) and (β) are periodically repeated, and the length of the period is determined by the laser of the semiconductor laser device of the present invention. Equal to the cavity length.

The halftone light shielding pattern (α) of the photomask is designed so that the light transmittance is constant in the stripe direction.

In the halftone light shielding pattern (β) of the photomask, the light transmittance changes in a gradient direction in the stripe direction, and the light transmittance gradient is periodically repeated. As shown in FIG. 8B, the length of the period is equal to the chip width of the semiconductor laser device of the present invention, and the light transmittance at the center of the period is the halftone light shielding pattern (α). It is designed to be equal to the light transmittance. In the present embodiment, as shown in FIG. 8 (c), a halftone light shielding pattern (β) having a relative change of the light transmittance gradient of ± 25% from the center of the period was used.

[0083] The photomask, Cr _x O _y N _z as a mask material of the halftone _{portion, Mo w Si x O y N} z, S
It can be manufactured by using i _x N _y (w, x, y, z is 1 or more) or the like and changing the deposition rate or the composition at the time of vapor deposition of the mask material on the glass substrate.

Patterning using an exposure apparatus is performed by using the above-described photomask, in the [011] direction of the n-type GaAs substrate 200 in which one main surface is inclined by 10 degrees from the (100) direction to the [011] direction. Alignment is performed so that the stripe directions of the halftone pattern coincide with each other, the energy exposure amount to be irradiated is adjusted, and the resist is exposed only at a certain depth from the surface. The portion of the halftone light shielding pattern (α) corresponds to the region inside the laser resonator 201 in FIG. 6, and the halftone light shielding pattern (β)
6 corresponds to the region near the laser resonator end face 201 in FIG. The resist exposed in this manner is developed and baked because the cross-linking depth of the photosensitive molecules in the resist changes along the periodic light transmittance gradient in each photomask in the region of the halftone pattern. By performing a known process such as this, a resist mask 216 shown in FIG. 7A is formed.

The region near the laser resonator end face of the resist mask 216 is formed in a stripe shape extending in the [011] direction and having a width of 40 μm, and the film thickness is gradually changed in the [011] direction. It has a thickness distribution, and the stripe pitch is 800 μm, which is the same as the laser cavity length. The region inside the laser cavity of the resist mask 216 has a uniform film thickness distribution, and the film thickness is the same as the film thickness at the chip center position in the [011] direction in the region near the laser cavity end face. Has become.

Then, using a dry etching technique,
Etching is performed until the resist mask 216 formed on the surface of the n-type GaAs substrate 200 in which one main surface of the substrate is inclined at 10 degrees from the (100) direction to the [011] direction is removed, and FIG. It is processed into the n-type GaAs substrate 201 shown.

The n-type GaAs obtained by the above processing method
As a result of measuring the s-substrate 201 with a scanning electron microscope (SEM), one main surface of the inner region of the laser resonator was (100)
The plane is inclined by 10 degrees in the [011] direction from the plane, and one principal plane in the vicinity of the end face of the laser resonator is the (100) plane.

From this, one main surface of the n-type GaAs substrate in the region near the laser cavity facet and the main surface in the region inside the laser cavity are inclined in the same direction from (100), and the n-type GaAs substrate in the region near the laser cavity facet. It is clear that the inclination angle of the GaAs substrate can be processed to be smaller than the laser cavity internal region.

Next, processed by the above manufacturing method,
One main surface of the laser cavity internal region is changed from (100) to [01].
N] type GaAs substrate 2 inclined at 10 degrees in the [1] direction and having one (100) plane as one principal surface in the vicinity of the laser resonator end face.
01 on the n-type AlGaAs first by MOCVD.
Clad layer 202, MQW active layer 203, p-type AlGa
The As second cladding layer 204, the p-type etching stop layer 205, the p-type AlGaAs third cladding layer 206, and the p-type GaAs protection layer 207 are epitaxially grown (FIG. 7C).

Thereafter, a ridge stripe is formed on the surface of the p-type GaAs protective layer 207 in the region near the laser resonator end face where one main surface of the n-type GaAs substrate 201 is the (100) plane by plasma CVD and photolithography. Striped dielectric film 21 having a width of 40 μm in a direction orthogonal to the direction
7 is formed. In the present embodiment, Si _x O _y as a dielectric film 217 (x, y is 1 or more) with a film, the pitch of the stripe was the same 800μm as the resonator length (Fig. 7
(D)).

Next, annealing by the RTA method is performed.
The band gap energy of the MQW active layer (window region) 213 immediately below the Si _x O _y (x, y is 1 or more) film 217 which is a dielectric film is changed to the band of the MQW active layer (active region) 203 in the laser cavity internal region. Make it larger than the gap energy.

Using a part of the wafer annealed by the RTA method, the window region 213 and the active region 2 are formed by the PL method.
03 were measured.

As a result, one principal surface of the substrate in the region inside the laser resonator is inclined by 10 degrees from (100) to the [011] direction, and one principal surface of the substrate in the region near the end surface of the laser resonator is ( In the wafer obtained by the manufacturing method of the present invention using the n-type GaAs substrate 201 which is the (100) plane, the emission spectrum from the window region 213 shifts to a wavelength shorter by 30 nm than the emission spectrum from the active region 203. Was.

From this, one main surface of the n-type GaAs substrate in the region near the laser cavity facet and in the region inside the laser cavity are inclined in the same direction from (100), and in the region near the laser cavity facet. A semiconductor laser device in which the tilt angle of the n-type GaAs substrate is smaller than the laser cavity internal region and the band gap of the active layer in the region near the laser cavity end face is larger than the band gap of the active layer in the laser cavity internal region. It is clear that

Further, using a part of the wafer after the annealing, the C-V method is used to form the p-type region in the vicinity of the laser cavity facet where one main surface of the n-type GaAs substrate 201 is the (100) plane.
The carrier concentration of the second and third cladding layers 204 and 206 of the n-type AlGaAs and one main surface of the n-type GaAs substrate 201 are (1).
The carrier concentration of the p-type AlGaAs second and third cladding layers 204 and 206 in the laser resonator inner region inclined by 10 degrees from [00] to the [011] direction was measured.

As a result, p in the region near the end face of the laser resonator in which one main surface of the n-type GaAs substrate 201 is the (100) plane.
The carrier concentration of the second AlGaAs second cladding layer 204 is such that the one main surface of the n-type GaAs substrate 201 is inclined by 10 degrees from the (100) direction to the [011] direction in the p-type AlGaAs second cladding layer in the laser resonator inner region. 204 was lower than the carrier concentration. Further, the n-type GaAs substrate 2
The carrier concentration of the p-type AlGaAs third cladding layer 206 in the region near the laser cavity facet where one principal surface of the n-type GaAs substrate 101 is (100) plane is (10)
0) The p-type AlGaAs third cladding layer 206 in the laser cavity inner region inclined by 10 degrees in the [011] direction from the [011] direction.
Was lower than the carrier concentration.

Thus, the p-type AlGaAs second cladding layer 204 and the p-type AlGaAs third cladding layer 20
It is apparent that a semiconductor laser device having a lower carrier concentration in the region near the laser cavity end face than in the region inside the laser cavity is obtained.

Next, the Si _x O _y (x, y is 1 or more) film 217 which is the dielectric film formed in the region near the end face of the laser resonator is removed, and the p-type film is formed by using a known photolithography technique. A stripe-shaped resist mask 218 extending in the [01-1] or [0-11] direction is formed on the GaAs protective layer 207, and p is formed using a known etching technique.
P type G so as to reach the type etching stop layer 205.
The aAs protective layer 207 and the p-type AlGaAs third cladding layer 206 are processed into a striped ridge 215 having a width of about 3 μm and extending in the [01-1] or [0-11] direction (FIG. 7E).

Thereafter, the striped resist mask 218 formed on the p-type GaAs protective layer 207 is removed, and the p-type GaAs protective layer 207 and the p-type AlGaAs third cladding layer 206 are formed by the second MOCVD method. The side surface of the ridge 215 is embedded with an n-type AlGaAs current block layer 208 and a p-type GaAs planarization layer 209 (FIG. 7F).

Using a part of the wafer, SEM
As a result of measuring the cross section of the wafer, the side surface of the ridge 215 is very flatly buried by the n-type AlGaAs current blocking layer 208 and the p-type GaAs planarization layer 209.
Also, the p-type G of the p-type AlGaAs third cladding layer 206
The variation of the ridge stripe width on the aAs protective layer 207 side (upper side) in the wafer surface was ± 10%, and the ridge 215 was formed with very good control.

If the width of the upper ridge stripe is too narrow, p
Since the process failure in which the n-type GaAs protective layer 207 is inclined is likely to occur, one main surface of the n-type GaAs substrate in the region near the laser cavity end face and the region inside the laser cavity is (10).
0) is a surface inclined in the [011] or [0-1-1] direction, and the direction in which the ridge-shaped stripe is formed is the [0-11] or [01-1] direction. It can be seen that by using the semiconductor laser device of the present invention, a semiconductor laser device can be manufactured with high yield over the entire surface of the wafer.

Further, the current confinement portion of the wafer was measured by an X-ray diffraction method. n-type AlGaAs current blocking layer 2
If the crystallinity of Sample No. 08 is poor, the function as a current confinement part may be reduced and a leak current may occur. However, as a result of the measurement, the half-width of the n-type AlGaAs current block layer 208 is very narrow, Was obtained, and there was no problem in particular.

Next, the p-type GaAs planarization layer 209 formed on the side surface of the ridge 215 and the p-type GaAs planarization layer 209 formed on the ridge 215 having a width of 40 μm are formed by using a known photolithography technique. A resist mask 219 is formed in a region near the end face of the stripe-shaped laser resonator, and the n-type AlGaAs current blocking layer 208 at the opening of the resist mask 219 is formed by a known etching technique.
And the p-type GaAs planarization layer 209 is selectively removed (FIG. 7G).

N-type AlGa formed on ridge 215
As current blocking layer 208 and p-type GaAs planarization layer 20
9 is also used as the step of forming the current non-injection region 214, so that the number of steps can be reduced. Further, the current non-injection region 2 formed by the above-described process can be reduced.
Since 14 is located immediately above the window region 213, current injection into the window region is prevented, and carrier loss due to the presence of vacancy defects in the window region can be suppressed, so that reactive current that does not contribute to light emission is reduced.

Thereafter, the resist mask 219 formed on the p-type GaAs planarization layer 209 is removed, and the third M
The p-type GaAs contact layer 210 is formed by the OCVD method (FIG. 7H). Further, a p-electrode 211 is formed on the upper surface, and an n-electrode 212 is formed on the lower surface.

Next, a scribe line is inserted almost in the center of the region near the end face of the laser resonator having a width of 40 μm, and the laser is divided into bars in the length of the resonator.

Thus, one main surface of the n-type GaAs substrate 201 in the region near the laser cavity end face and in the region inside the laser cavity is changed from (100) to [011] or [0-1-1].
Since the ridge-shaped stripe is formed in the [01-1] or [0-11] direction, the light emission direction is [01-1] or [0-1]. [-11] The resonator can be formed in a direction perpendicular to the direction.

Finally, the light emission on both sides of the bar is coated with a reflection film, and further divided so as to have an arbitrary chip width. A window region of about 20 μm and a laser cavity end face of an 800 μm length resonator are formed. An element having a current non-injection region is manufactured.

The characteristics of the semiconductor laser device obtained by the above-described manufacturing method of the present invention were measured.

For comparison, one principal surface of the substrate in the laser cavity internal region and the region near the laser cavity end face is (1).
The characteristics of a conventional semiconductor laser device obtained by changing to an n-type GaAs substrate inclined at 10 degrees from the (00) plane to the [011] direction were also measured.

As a result, the oscillation wavelength (λ) at CW of 120 mW was 785 nm for both the present invention and the prior art semiconductor laser device, and the result of the maximum light output test showed that the maximum light output of the prior art semiconductor laser device was 220 mW. The semiconductor laser device of the present invention is COD-free even at an optical output of 300 mW or more. When these devices were subjected to a reliability test at 70 ° C. and 120 mW, the average life of the conventional semiconductor laser device was 100 hours or less. On the other hand, in the semiconductor laser device of the present invention, the average life was improved to about 3000 hours, that is, about 30 times or more.

In the semiconductor laser device of the present invention, the carrier concentration near the laser resonator end face is lower than that in the laser resonator inner region, and the active region 203 and the window region 2
13, the window region 213 of the laser beam formed in the active region 203 is increased.
This is because the absorption in

In this embodiment, the n-type GaAs substrate in which the main surface inside the laser cavity and one main surface near the laser cavity end face is inclined from the (100) direction to the [011] direction is used. The same effect as described above can be obtained even with an n-type GaAs substrate in which the inner region and one main surface near the laser resonator end surface are inclined in the [0-1-1] direction from (100).

In the present embodiment, the dielectric film of Si _x O
_y (x, y is 1 or more), but the film 217 is formed using a plasma CVD method, even by using a sputtering method, Si _x O
At the time of forming a _y (x, y is 1 or more) film, vacancy atoms are generated by plasma damage on the surface of the epitaxially grown wafer, and the active layer in the vicinity of the laser cavity end face is effectively removed from the laser cavity internal region. Active layer (active area)
Because a window region with a wide bandgap can be formed more effectively,
The same effects as above can be obtained.

[0115] In the present embodiment, Si _x O as a dielectric film
_y (x, y is 1 or more) was used _{film, Si x N y, Si x} O
If _{y N z (x, y,} z is 1 or more) either it can be holes atoms to produce a p-type GaAs protective layer 207 of the lower dielectric layer 217, effectively laser resonator end face Since a window region having a wider bandgap can be effectively formed in the active layer in the vicinity region than in the active layer (active region) in the laser cavity inner region, the same effect as described above can be obtained.

In this embodiment, the length of the region in the vicinity of the end face of the laser resonator is 20 μm. However, if the length is in the range of 10 μm to 60 μm, the same effect as described above can be obtained.

In this embodiment, an AlGaAs semiconductor laser has been described. However, similar effects can be obtained with an AlGaInP semiconductor laser. (Embodiment 3) In this embodiment, the inclination angle of the n-type GaAs substrate from the (100) plane in the region near the laser resonator end face in the semiconductor laser device of the present invention described in Embodiment 2 will be examined.

First, using the manufacturing method described in the second embodiment, one principal surface of the substrate in the laser cavity inner region is (10%).
0) is inclined 10 degrees in the [011] direction from the (100), and one principal surface of the substrate in the vicinity of the laser cavity end face is 0, 2, 5, 10, 15, 20 degrees in the [011] direction from the (100). Six kinds of inclined n-type GaAs substrates were prepared.

Next, the n-type AlGaAs first cladding layer, MQW active layer, p-type AlGaAs second cladding layer, p-type etching stop layer, p-type AlGaAs
An s third cladding layer and a p-type GaAs protective layer are epitaxially grown.

Thereafter, the surface of the p-type GaAs protective layer in the vicinity of the laser cavity end face of each of the six types of wafers was formed into a stripe shape having a width of 40 μm in a direction orthogonal to the ridge stripe by plasma CVD and photolithography. a dielectric film Si _x O _{y (x, y} is 1 or more) to form a film.

Next, RT is applied to each of the above six types of wafers.
Annealing by the method A was performed.

Using a part of the six types of wafers annealed by the RTA method, a PL film is
i _x O _{y (x, y} is 1 or more) MQW active layer immediately below layer (window area) and the MQW active layer of the laser resonator inner area of each of the wavelengths of the (active area) were measured.

FIG. 9 shows the relationship between the tilt angle of the n-type GaAs substrate in the region near the laser cavity facet and the amount of wavelength shift of the window region with respect to the wavelength of the active region in the PL measurement. At this time, all the wavelengths in the window region were shifted to the shorter wavelength side with respect to the wavelength in the active region. The vertical axis in FIG. 9 represents the wavelength shift amount (nm) of the window region with respect to the wavelength of the active region, and the horizontal axis represents the tilt angle (degree) of the n-type GaAs substrate in the region near the laser resonator end face.

As can be seen from FIG. 9, one main surface of the substrate in the region near the laser cavity end face is obtained by using an n-type GaAs substrate inclined from the (100) to the [011] direction by 0 or 2 degrees. the _{wafer, Si x O y (x,} y is 1 or more) film emission spectrum from the MQW active layer immediately below, 3 than the emission spectrum from the MQW active layer of the laser resonator inner area
The wavelength is shifted to the shorter wavelength side by 0 nm, and one main surface of the substrate in the region near the end face of the laser resonator changes from (100) to [01].
N-type GaAs inclined at 10, 15, and 20 degrees in the [1] direction
s at wafer obtained by using the _{substrate, Si x O y (x,} y
The emission spectrum from the MQW active layer immediately below the film had the same wavelength as the emission spectrum from the MQW active layer in the inner region of the laser resonator, and there was no wavelength shift.

Further, after annealing by the RTA method, 6
Subsequently, semiconductor laser devices were manufactured from the wafers of the types by using the manufacturing method described in Example 2, and a maximum light output test was performed on each of the six types of semiconductor laser devices.

As a result, one main surface of the substrate in the region near the laser cavity end face is shifted from (100) to [011] direction by 5, 1
In a semiconductor laser device obtained using an n-type GaAs substrate inclined at 0, 15, and 20 degrees, 160 to 220 mW is used.
Further, in a semiconductor laser device obtained by using an n-type GaAs substrate in which one principal surface of the substrate in the region near the end face of the laser resonator is inclined from the (100) by 0 or 2 degrees in the [011] direction. And COD-free even at an optical output of 300 mW or more.

Accordingly, a COD-free semiconductor laser device can be manufactured by setting the inclination angle of the n-type GaAs substrate from the (100) plane in the region near the laser cavity facet to 0 ° or more and less than 5 °. The thing is clear.

In the present embodiment, an n-type GaAs substrate in which one main surface of the laser cavity inner region and the region near the laser cavity end face is inclined in the [011] direction from (100) is used. Were examined using the semiconductor laser device and the method for manufacturing the semiconductor laser device described above, and one main surface of the laser resonator inner region and the region near the laser resonator end surface is inclined from (100) to the [01-1] direction. The same effects as described above can be obtained by using the semiconductor laser device described in the first embodiment and the method for manufacturing the same using a GaAs substrate. (Embodiment 4) In this embodiment, the inclination angle of the n-type GaAs substrate from the (100) plane in the laser resonator inner region in the semiconductor laser device of the present invention described in Embodiment 2 will be examined.

First, using the manufacturing method described in the second embodiment, one principal surface of the substrate in the region near the laser cavity end face is (1).
00) plane, and one main surface of the substrate in the laser cavity inner region is 0, 2, 5, 1 from (100) in the [011] direction.
Six types of n-type GaAs substrates inclined at 0, 15, and 20 degrees were prepared.

Next, the n-type AlGaAs first cladding layer, MQW active layer, p-type AlGaAs second cladding layer, p-type etching stop layer, p-type AlGaAs
An s third cladding layer and a p-type GaAs protective layer are epitaxially grown.

Thereafter, the surface of the p-type GaAs protective layer in the region near the laser cavity end face of each of the six types of wafers was formed into a stripe shape having a width of 40 μm in a direction orthogonal to the ridge stripe by plasma CVD and photolithography. a dielectric film Si _x O _{y (x, y} is 1 or more) to form a film.

Next, RT is applied to each of the above six types of wafers.
Annealing by the method A was performed.

Using a part of the six kinds of wafers annealed by the RTA method, the inside of the laser resonator was subjected to rocking curve measurement using an X-ray diffraction apparatus.

FIG. 10 shows the relationship between the half-width of the AlGaAs peak near the active layer in the laser resonator internal region and the inclination angle of the n-type GaAs substrate in the laser resonator internal region in the rocking curve measurement.

The vertical axis in FIG. 10 is the half width (second) of the AlGaAs peak, and the horizontal axis is n-type GaAs in the laser resonator internal region.
This is the inclination angle (degree) from the (100) plane of the s substrate.

As can be seen from FIG. 10, the half-width of the AlGaAs peak in the laser cavity internal region is small because of the (100) of the n-type GaAs substrate in the laser cavity internal region.
The half-width of the AlGaAs peak in a wafer using a substrate having a tilt angle of 5, 10, 15 degrees from the surface to the [011] direction is very small. wide.

The half-width of the rocking curve indicates the crystallinity of the epitaxially grown AlGaAs. The narrower the half-width, the better the crystallinity.
The FWHM of the GaAs peak is the Al width near the active layer.
Since the FWHM is the half-width of the GaAs peak, [0] from the (100) plane of the n-type GaAs substrate in the laser cavity internal region.
It is apparent that when the inclination angle to the [11] direction is in the range of 5 degrees or more and 15 degrees or less, the deterioration of crystallinity in the vicinity of the epitaxially grown active layer can be suppressed even by annealing by the RTA method.

Further, after annealing by the RTA method, 6
Subsequently, semiconductor laser devices were manufactured using the manufacturing method described in Example 2, and a long-term reliability test was performed on each of the six types of semiconductor laser devices at 70 ° C. and 120 mW. . As a result, the average of the semiconductor laser device obtained by using the n-type GaAs substrate in which one main surface of the substrate in the laser cavity inner region is inclined from the (100) by 0, 2, and 20 degrees in the [011] direction. Life is 100-3
In contrast to the time of 00 hours, one main surface of the substrate in the laser cavity internal region is shifted from (100) to [011] direction by 5, 1
The average life of the semiconductor laser device obtained by using the n-type GaAs substrate inclined by 0.15 degrees was 3000 hours or more.

Therefore, by setting the angle of inclination of the n-type GaAs substrate from the (100) plane in the laser cavity inner region to 5 degrees or more and 15 degrees or less, a high-quality and high-reliability semiconductor laser device is obtained. It is clear that can be produced.

In the present embodiment, an n-type GaAs substrate in which one main surface of the laser cavity inner region and the region near the laser cavity end face is inclined in the [011] direction from (100) is used. Were examined using the semiconductor laser device and the method for manufacturing the semiconductor laser device described above, and one main surface of the laser resonator inner region and the region near the laser resonator end surface is inclined from (100) to the [01-1] direction. The same effects as described above can be obtained by using the semiconductor laser device described in the first embodiment and the method for manufacturing the same using a GaAs substrate. (Embodiment 5) FIG. 11 is a sectional view showing the structure of a semiconductor laser device of Embodiment 5. 11A is a perspective view including a light emitting end face, and FIG. 11B is a perspective view taken along the line Ia-I in FIG.
FIG. 11A is a cross-sectional view of the waveguide taken along line a ′, and FIG.
FIG. 4 is a cross-sectional view taken along line Ib-Ib ′ in the layer thickness direction. Further, 301 has a main surface of (10
An n-type GaAs substrate which is inclined by 15 degrees from [0] to the [011] direction and one main surface of the region near the laser resonator end face is the (100) plane, 302 is an n-type AlGaInP first cladding layer, and 303 is a barrier Layer (M) in which a multiple quantum well structure in which layers and well layers are alternately stacked is sandwiched between optical guide layers.
QW active layer), 304 is a p-type AlGaInP second cladding layer, 305 is a p-type etching stop layer, 306 is a p-type AlGaIn comprising a ridge stripe in the resonator direction.
P third cladding layer, 307 is a p-type GaInP intermediate layer, 3
08 is a p-type GaAs protective layer, 309 is an n-type GaAs current block layer formed so as to bury the side surface of the p-type AlGaInP third cladding layer composed of a ridge stripe, 3
10 is a p-type GaAs contact layer, 311 is a p-side electrode,
Reference numeral 312 denotes an n-side electrode. Reference numeral 313 denotes a region (window region) in which the bandgap energy of the MQW active layer 303 near the laser resonator end face is larger than the bandgap energy of the MQW active layer 303 inside the laser resonator.
AlGaInP third cladding layer 306, p-type GaIn
Striped ridges composed of a P intermediate layer 307 and a p-type GaAs protective layer 308, 317 is a dielectric film formed in a stripe shape in a direction orthogonal to the ridge stripe.
i _x O _{y (x, y} is 1 or more) is a membrane.

Next, a manufacturing method will be described with reference to FIG.

One main surface of the substrate is changed from (100) to [011].
A resist is applied on the surface of the n-type GaAs substrate 300 inclined at 15 degrees in a direction so as to have a thickness of 0.2 μm and a distribution within ± 2%, and after prebaking, patterning is performed using an exposure apparatus. I do. The photomask used at this time has two types of striped halftone light shielding patterns (α) and (β) periodically repeated as shown in FIG. The length is equal to the laser cavity length of the semiconductor laser device of the present invention. In the halftone light shielding pattern (α) of the photomask,
The light transmittance is designed to be constant in the stripe direction.

In the halftone light shielding pattern (β) of the photomask, the light transmittance changes obliquely in the stripe direction, and the light transmittance tilt is periodically repeated. As shown in FIG. 13B, the length of the period is equal to the chip width of the semiconductor laser device of the present invention, and the light transmittance at the center of the period is the halftone light shielding pattern (α). It is designed to be equal to the light transmittance. In the present embodiment, the relative change amount of the light transmittance gradient in the halftone light shielding pattern (β) is ± 37.5% from the center of the period as shown in FIG.

In the patterning using the exposure apparatus, the photomask is used for the patterning in the [011] direction of the n-type GaAs substrate 300 in which one main surface of the substrate is inclined by 15 degrees from the (100) direction to the [011] direction. Alignment is performed so that the stripe directions of the halftone pattern coincide with each other, the energy exposure amount to be irradiated is adjusted, and the resist is exposed only at a certain depth from the surface. The half-tone light-shielding pattern (α) corresponds to the laser resonator inner area 301 shown in FIG. 11, and the half-tone light-shielding pattern (β) corresponds to the laser resonance area 301 shown in FIG. This corresponds to the region near the container end face.

In the resist thus exposed, the cross-linking depth of the photosensitive molecules in the resist changes along the periodic light transmittance gradient in each photomask in the region of the halftone pattern. By performing known processing such as development and baking, a resist mask 316 shown in FIG. 12A is formed.

The region near the laser resonator end face of the resist mask 316 is formed in a stripe shape extending in the [011] direction and having a width of 40 μm, and has a film thickness which is inclined in the [011] direction. It has a thickness distribution, and the stripe pitch is 800 μm, which is the same as the laser cavity length. The region inside the laser cavity of the resist mask 216 has a uniform film thickness distribution, and the film thickness is the same as the film thickness at the chip center position in the [011] direction in the region near the laser cavity end face. Has become.

Then, using a dry etching technique,
Etching is performed until the resist mask 316 formed on the surface of the n-type GaAs substrate 300 in which one main surface of the substrate is inclined by 15 degrees in the [011] direction from (100) is removed, and FIG. It is processed into the n-type GaAs substrate 301 shown.

N-type GaAs obtained by the above processing method
As a result of measuring the s-substrate 301 with a scanning electron microscope (SEM), one main surface of the inner region of the laser resonator was (100)
The plane is inclined by 15 degrees in the [011] direction from the plane, and one principal plane in the vicinity of the laser resonator end face is the (100) plane.

Next, processed by the above manufacturing method,
One main surface of the laser cavity internal region is changed from (100) to [01].
N] -type GaAs substrate 3 inclined at 15 degrees in the [1] direction and having one (100) plane as one main surface in the vicinity of the laser cavity end face.
01 on n by molecular beam epitaxy (MBE)
-Type AlGaInP first cladding layer 302, MQW active layer 303, p-type AlGaInP second cladding layer 304, p-type AlGaInP
The p-type AlGaInP third cladding layer 306, the p-type GaInP intermediate layer 307, and the p-type GaAs protection layer 308 are epitaxially grown (FIG. 12C).

After that, the ridge stripe is formed on the surface of the p-type GaAs protective layer 308 in the region near the end face of the laser resonator where one main surface of the n-type GaAs substrate 301 is the (100) plane by plasma CVD and photolithography. Striped dielectric film 31 having a width of 40 μm in a direction orthogonal to the direction
7 is formed. In the present _{embodiment, Si x O y (x,} y is 1 or more) using a film as the dielectric film 317, the pitch of the stripe was the same 800μm as the resonator length (Fig. 12
(D)).

Next, annealing by the RTA method is performed.
The band gap energy of the MQW active layer (window region) 313 immediately below the Si _x O _y (x, y is 1 or more) film 317 which is a dielectric film is converted to the band of the MQW active layer (active region) 303 in the laser cavity internal region. Make it larger than the gap energy.

Using a part of the wafer annealed by the RTA method, the window region 313 and the active region 3 are formed by the PL method.
03 were measured.

As a result, one principal surface of the substrate in the laser cavity inner region is inclined by 15 degrees from the (100) direction to the [011] direction, and one principal surface of the substrate in the region near the laser cavity end surface is ( In the wafer obtained by the manufacturing method of the present invention using the n-type GaAs substrate 301 as the (100) plane, the emission spectrum from the window region 313 is shifted to a wavelength shorter by 50 nm than the emission spectrum from the active region 303. Was.

Further, by using a part of the annealed wafer by the CV method, the p-type region in the vicinity of the laser cavity facet where one main surface of the n-type GaAs substrate 301 is the (100) plane is obtained.
Concentration of the second and third cladding layers 304 and 306 of the p-type AlGaInP and the p-type AlGaInP in the laser resonator inner region where one main surface of the n-type GaAs substrate 301 is inclined by 15 degrees from the (100) to the [011] direction. The carrier concentration of the second and third cladding layers 304 and 306 was measured.

As a result, p in the region near the end face of the laser resonator where one main surface of the n-type GaAs substrate 301 is the (100) plane.
The carrier concentration of the second AlGaInP cladding layer 304 is such that the one main surface of the n-type GaAs substrate 301 is inclined at 15 degrees from the (100) direction to the [011] direction by 15 degrees in the laser resonator inner region. The carrier concentration was lower than 304. Further, the carrier concentration of the p-type AlGaInP third cladding layer 306 in the region near the laser cavity facet where one main surface of the n-type GaAs substrate 301 is the (100) plane is such that one main surface of the n-type GaAs substrate 301 is (100). ) Was lower than the carrier concentration of the p-type AlGaInP third cladding layer 306 in the laser resonator inner region inclined by 15 degrees in the [011] direction.

Next, while leaving the Si _x O _y (x, y is 1 or more) film 317 which is the dielectric film formed in the region near the end face of the laser cavity, using a known photolithography technique, a dielectric film Si _x O _{y (x, y} is 1 or more)
[01-1] on the film 317 and the p-type GaAs protective layer 308
Or [0-11] to form a stripe-shaped resist mask 318 extending in the direction, using a known etching technique, a dielectric film so as to reach the p-type etching stop layer 305 Si _x O _{y (x} , Y is 1 or more) film 317, p-type GaAs protective layer 308 and p-type GaInP intermediate layer 30
7 and the p-type AlGaInP third cladding layer 306
It is processed into a stripe-shaped ridge 315 having a width of 5 μm (FIG. 12E).

[0157] Thereafter, a dielectric film Si _x O _{y (x, y}
The striped resist mask 318 formed on the film 317 and the p-type GaAs protective layer 308 is removed, and the p-type AlGaInP third cladding layer 306 and the p-type GaInP intermediate layer 307 are formed by the second MBE method. , The side surface of the ridge 315 composed of the p-type GaAs protective layer 308 is n
GaAs current blocking layer 309 (FIG. 12)
(F)).

Using a part of the wafer, SEM
As a result of measuring the cross section of the wafer, the ridge 315 becomes very flat.
Was buried with an n-type GaAs current block layer 309.

The n-type GaAs current blocking layer 309
If the crystallinity of the wafer is poor, the function as a current confinement portion may be reduced and a leak current may occur. However, as a result of measuring the current confinement portion of the wafer by an X-ray diffraction method, n-type Ga
The half width of the As current blocking layer 309 was very narrow, and a film with good crystallinity was obtained, and there was no problem in particular.

Next, a resist mask 319 is formed on the n-type GaAs current blocking layer 309 formed on the side surface of the ridge 315 by using a known photolithography technique, and the resist mask 3 is formed by using a known etching technique.
The n-type GaAs current block layer 309 in the 19 openings is selectively removed (FIG. 12G).

Thereafter, the n-type GaAs current blocking layer 30
The resist mask 319 formed on the substrate 9 is removed, and a p-type GaAs contact layer 310 is formed by a third MBE method (FIG. 12H). Furthermore, a p-electrode 31 is provided on the upper surface.
1. An n-electrode 312 is formed on the lower surface.

Next, a scribe line is inserted substantially in the center of the region near the end face of the laser resonator having a width of 40 μm, and the length of the resonator is divided into bars. Finally, the light emission on both sides of the bar is coated with a reflective film. Then, the device is further divided into an arbitrary chip width, and an element having a window region of about 20 μm and a current non-injection region at a laser resonator end face of a resonator having a length of 800 μm is manufactured.

[0163] The semiconductor laser of this embodiment, the surface of the p-type GaAs protective layer 308 serving as a laser resonator end face region near a dielectric film Si _x O _{y (x, y} is 1 or more) to form a film 317 Since the step also serves as a step of forming the current non-injection region, the number of steps can be reduced, and furthermore, the dielectric film formed by the above process, Si _x O
_y (x and y are 1 or more) Since the film 317 also serves as a current non-injection region, a region immediately below the current non-injection region serves as a window region 313, and there is no displacement, so that current injection into the window region is prevented. Since carrier loss due to the presence of vacancy defects in the region can be suppressed, reactive current that does not contribute to light emission is reduced.

The characteristics of the semiconductor laser device obtained by the above-described manufacturing method of the present invention were measured.

As a result, the maximum optical output is COD-free even at an optical output of 150 mW or more, and 70 ° C. and 70 mW
When a reliability test was performed, stable running was confirmed over 3000 hours.

In the present embodiment, the n-type GaAs substrate in which one main surface in the laser cavity inner region and the region near the laser cavity end face is inclined in the [011] direction from (100) is used. The same effect as described above can be obtained even with an n-type GaAs substrate in which the inner region and one main surface near the laser resonator end surface are inclined in the [0-1-1] direction from (100).

In the present embodiment, the inclination angle of the n-type GaAs substrate in the laser cavity inner region is 15 degrees. However, if the inclination angle is in the range of 5 degrees to 15 degrees, the same effect as described above can be obtained.

In this embodiment, the tilt angle of the n-type GaAs substrate in the region near the laser resonator end face was 0 degree,
Within the range of not less than 5 degrees and less than 5 degrees, the same effect as above can be obtained.

In this embodiment, the length of the region in the vicinity of the end face of the laser resonator is 20 μm. However, if the length is in the range of 10 μm to 60 μm, the same effect as described above can be obtained.

In the present embodiment, the dielectric film of Si _x O
_y (x, y is 1 or more), but the film 317 is formed using a plasma CVD method, even by using a sputtering method, Si _x O
At the time of forming a _y (x, y is 1 or more) film, vacancy atoms are generated by plasma damage on the surface of the epitaxially grown wafer, and the active layer in the vicinity of the laser cavity end face is effectively removed from the laser cavity internal region. Active layer (active area)
Because a window region with a wide bandgap can be formed more effectively,
The same effects as above can be obtained.

[0171] In the present embodiment, Si _x O as a dielectric film
_y (x, y is 1 or more) was used _{film, Si x N y, Si x} O
If _{y N z (x, y,} z is 1 or more) either it can be holes atoms to produce a p-type GaAs protective layer 308 of the lower dielectric layer 317, effectively laser resonator end face Since a window region having a wider bandgap can be effectively formed in the active layer in the vicinity region than in the active layer (active region) in the laser cavity inner region, the same effect as described above can be obtained.

In this embodiment, an AlGaInP-based semiconductor laser has been described. However, similar effects can be obtained with an AlGaAs-based semiconductor laser.

[0173]

As described above, in the present invention, one principal surface of the first conductivity type substrate is inclined from (100), and the inclination angle of the first conductivity type substrate in the region near the laser cavity end face. Is smaller than the laser cavity internal region, and the band gap of the active layer in the region near the laser cavity end face is larger than the band gap of the active layer in the laser cavity internal region.
It is possible to suppress diffusion of impurities such as Zn atoms into the active layer in the laser cavity internal region, and to effectively make the active layer in the region near the laser cavity end face more forbidden than the active layer in the laser cavity internal region. Since a wide window region can be formed, the driving current and voltage at the time of high output are reduced, and a semiconductor laser device having excellent long-term reliability in high output driving can be obtained.

In the present invention, one principal surface of the first conductivity type substrate in the region near the laser cavity end face and in the region inside the laser cavity is (100) to [0-11] or [01-].
1], and the direction in which the ridge-shaped stripes are formed is [011] or [0−
1-1], the light emission direction is [011].
Alternatively, it is possible to form a resonator in the direction perpendicular to the [0-1-1] direction, and it is easy to selectively remove unnecessary layers formed on the ridge. A semiconductor laser device with reduced driving current and voltage can be obtained stably.

Further, in the present invention, one main surface of the first conductivity type substrate in the region near the laser cavity end face and in the region inside the laser cavity is (100) to [011] or [0-1-).
1], and the direction in which the ridge-shaped stripe is formed is [0-11] or [0-11].
1-1], the light emission direction is [0-1].
The resonator can be formed in a direction perpendicular to the [1] or [01-1] direction, and variations in the ridge stripe width in the wafer surface can be suppressed. A semiconductor laser device excellent in the above can be obtained.

In the present invention, the inclination angle of the first conductivity type substrate in the region near the laser cavity end face is not less than 0 degree and less than 5 degrees, so that the diffusion of the vacancy atoms is not hindered. A sufficient amount of vacancy atoms diffuse toward the substrate,
Since the band gap of the active layer in the region near the laser cavity end face can be made larger than the band gap of the active layer in the region inside the laser cavity, a COD-free semiconductor laser device can be obtained.

Further, in the present invention, the inclination angle of the first conductivity type substrate in the laser cavity internal region is not less than 5 degrees and not more than 15 degrees. Therefore, even if annealing is performed by the RTA method, the epitaxially grown active layer is formed. It is possible to suppress deterioration of crystallinity in the vicinity, and to obtain a semiconductor laser device excellent in long-term reliability in high-output driving.

Further, in the present invention, the carrier concentration of the second conductive type second clad layer and the third conductive layer is lower in the region near the laser resonator end face than in the laser resonator internal region. The absorption of the laser beam by the second conductivity type impurity in the region near the end face can be reduced, and the active layer in the region near the laser cavity end face can be effectively made more effectively a forbidden band than the active layer (active region) in the laser cavity inner region. Since a wide window region can be formed, a semiconductor laser excellent in long-term reliability in high-output driving can be obtained.

Further, in the present invention, the dielectric film and each layer formed by epitaxial growth are annealed to generate holes under the dielectric film and to diffuse the holes until reaching the active layer. Making the band gap of the active layer in the vicinity of the laser cavity end face larger than the band gap of the active layer in the inside of the laser cavity. The diffusion of atoms and other impurities can be suppressed, and the active layer in the region near the laser cavity end face can be effectively formed as a window region having a wider bandgap than the active layer in the region inside the laser cavity. The driving current / voltage of the semiconductor laser device is reduced, and a semiconductor laser device excellent in long-term reliability in high-output driving can be obtained.

Further, in the present invention, one principal surface of the first conductivity type substrate is inclined from (100), and the inclination angle of the first conductivity type substrate in the region near the laser resonator end surface is set to the laser cavity internal region. In the step of processing so as to be smaller, a first conductivity type substrate inclined from 0 degree to less than 5 degrees from the (100) plane is used, and the first conductivity type substrate in the laser cavity internal region is used. Since the main surface is processed so as to be inclined from 5 degrees to 15 degrees from the (100) plane, RT
Even if the annealing by the method A is performed, the deterioration of the crystallinity in the vicinity of the epitaxially grown active layer can be suppressed, and the diffusion of the vacancy atoms is not hindered, and a sufficient amount of the vacancy atoms is directed toward the substrate. It becomes possible to make the bandgap of the active layer near the laser cavity end face region larger than the bandgap of the active layer in the region inside the laser cavity, thereby providing excellent long-term reliability in high-power driving. And a COD-free semiconductor laser element can be obtained.

Further, in the present invention, one principal surface of the first conductivity type substrate is inclined from (100), and the inclination angle of the first conductivity type substrate in the vicinity of the laser resonator end surface is set to the laser resonator internal region. In the step of processing so as to be smaller, the first conductivity type substrate which is inclined from the (100) plane in a range of 5 degrees or more and 15 degrees or less is used, and the first conductivity type substrate in the region near the laser resonator end face is used. One principal plane is 0 from (100) plane
Since it is processed so that it is inclined in the range of 5 degrees or more and less than 5 degrees,
Even if annealing is performed by the RTA method, deterioration of crystallinity near the epitaxially grown active layer can be suppressed, and
The diffusion of the vacancy is not hindered, and a sufficient amount of the vacancy diffuses in the direction of the substrate. Since the gap can be made larger than the band gap of the layer, there is an effect that a COD-free semiconductor laser device having excellent long-term reliability in high-output driving and having a high COD is obtained.

Further, according to the present invention, the first conductivity type substrate can be easily processed into various shapes with good reproducibility simply by changing the shape of the resist mask. There is an effect that a COD-free semiconductor laser device having excellent properties can be obtained. Also, in the present invention, the resist mask periodically includes a stripe-shaped region in which the thickness of the resist mask changes obliquely in the stripe direction and a stripe-shaped region in which the thickness of the resist mask is uniform. By making the length of the period equal to the length of the laser cavity of the semiconductor laser device, one main surface of the first conductivity type substrate in the region near the laser cavity end face and in the region inside the laser cavity is (100). ), The inclination angle of the first conductivity type substrate in the region near the laser cavity end face can be made smaller than that in the region inside the laser cavity, so that the driving current and voltage at the time of high output are reduced, and high output driving is achieved. In this case, there is an effect that a semiconductor laser device having excellent long-term reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a semiconductor laser device according to a first embodiment.

FIG. 2 is an explanatory diagram of a method for manufacturing the semiconductor laser device of Example 1.

FIG. 3 is a view showing a photomask used in the method for manufacturing a semiconductor laser device of Example 1.

FIG. 4 is a diagram showing a depth direction distribution of Zn atoms in a laser cavity internal region before and after annealing of a semiconductor laser device of the present invention.

FIG. 5 is a diagram illustrating a depth direction distribution of Zn atoms in a laser cavity internal region before and after annealing of a conventional semiconductor laser device.

FIG. 6 is a cross-sectional view illustrating a structure of a semiconductor laser device of Example 2.

FIG. 7 is an explanatory diagram of the method for manufacturing the semiconductor laser device of the second embodiment.

FIG. 8 is a diagram showing a photomask used in the method for manufacturing a semiconductor laser device of Example 2.

FIG. 9 is a diagram showing a relationship between an inclination angle of an n-type GaAs substrate in a region near an end face of a laser resonator and a wavelength shift amount of a window region with respect to a wavelength of an active region.

FIG. 10 shows Al in the vicinity of an active layer in a laser cavity internal region.
FWHM of GaAs peak and n in laser resonator internal region
FIG. 4 is a diagram showing a relationship between the inclination angles of the GaAs substrate.

FIG. 11 is a sectional view showing a structure of a semiconductor laser device of Example 6;

FIG. 12 is an explanatory diagram of the method for manufacturing the semiconductor laser device of the sixth embodiment.

FIG. 13 is a view showing a photomask used in the method for manufacturing a semiconductor laser device of Example 6.

FIG. 14 is a cross-sectional view showing the structure of a conventional semiconductor laser device.

FIG. 15 is an explanatory view of a conventional method for manufacturing a semiconductor laser device.

[Explanation of symbols]

100, 200, 300, 1001... N-type GaAs
Substrate 101... One principal surface in the vicinity of the laser cavity end face is (1)
00) to the [01-1] direction, and one main surface of the laser cavity inner region is shifted from (100) to [01- 1].
1] n-type GaAs substrate 201 inclined at 10 degrees in the direction 201.
00) plane, and one principal plane of the laser cavity internal region is (1).
N-type G inclined 10 degrees from [00] to [011] direction
aAs substrate 301... One principal surface in the vicinity of the laser resonator end face is (1)
00) plane, and one principal plane of the laser cavity internal region is (1).
N-type G inclined 15 degrees from [00) to the [011] direction
aAs substrate 102, 202 ... n-type AlGaAs first cladding layer 302 ... n-type AlGaInP first cladding layer 103, 203, 303 ... MQW active layer 104, 204 ... p-type AlGaAs second cladding layer 304 ··· p-type AlGaInP second cladding layer 105, 205, 305 ··· p-type etching stop layer 106, 206 ··· p-type AlGaAs third cladding layer 306 ··· p-type AlGaInP third cladding layer 307 ..P-type GaInP intermediate layers 107, 207, 308... P-type GaAs protective layers 108, 208... N-type AlGaAs current blocking layers 109, 209... P-type GaAs planarization layers 110, 210, 310 ..P-type GaAs contact layers 111, 211, 311... P-type electrodes 112, 212, 3 12 ... n-type electrode 113, 213, 313 ... window region 114, 214, 314 ... current non-injection region 115, 215, 315 ... stripe-shaped ridge 117, 217, 317 ... dielectric Body membrane 116, 118, 119, 216, 218, 219, 3
16, 318, 319 resist mask 1002 n-type AlGaAs lower cladding layer 1003 quantum well active layer 1003a region contributing to laser oscillation of quantum well active layer 1003b quantum well activity Window structure region formed near the laser cavity end face of the layer 1004a... P-type AlGaAs first upper cladding layer 1004b... P-type AlGaAs second upper cladding layer 1006. Proton injection region 1010: SiO ₂ film 1020: Laser resonator end face

Claims (10)

[Claims] 1. A first conductivity type cladding layer, an active layer, a second conductivity type cladding layer having a ridge-shaped stripe, and a first conductivity type current having an opening of the ridge-shaped stripe on a substrate of the first conductivity type. In a semiconductor laser device having a constriction layer and a laser resonator formed in the ridge-shaped stripe direction, one main surface of the substrate is inclined from a (100) plane or a (100) plane, and the laser resonance is formed. The inclination angle of the substrate in the region near the end face of the cavity is smaller than that in the region inside the laser resonator, and the band gap of the active layer in the region near the end surface of the laser cavity is reduced in the region inside the laser cavity. A semiconductor laser device having a larger band gap than the active layer. 2. The semiconductor laser device according to claim 1, wherein the substrate inclination direction of the region near the laser resonator end face and the laser resonator internal region are the same. 3. A principal surface of the substrate in a region near the end face of the laser cavity and in a region inside the laser cavity is inclined in a [0-11] direction or a [01-1] direction from a (100) plane. And the ridge stripe direction is [01].
3. The semiconductor laser device according to claim 2, wherein the direction is a [1] direction or a [0-1-1] direction. 4. A main surface of the substrate in a region near an end face of the laser resonator and in a region inside the laser resonator is inclined in a [011] direction or a [0-1-1] direction from a (100) plane. And the ridge stripe direction is [0-
The semiconductor laser device according to claim 2, wherein the semiconductor laser device is in the [11] direction or the [01-1] direction. 5. The laser resonator according to claim 1, wherein a tilt angle of the substrate in a region near an end face of the laser resonator is not less than 0 degree and less than 5 degrees, and a tilt angle of the substrate in a region inside the laser resonator is not less than 5 degrees and not more than 15 degrees. The semiconductor laser device according to claim 1, wherein: 6. The second conductive type cladding layer according to claim 1, wherein the carrier concentration is lower in a region near the end face of the laser resonator than in a region inside the laser resonator. The semiconductor laser device according to any one of the above. 7. When manufacturing the semiconductor laser device according to claim 1, one principal surface of the substrate is inclined from the (100) plane, and the inclination angle is set in the laser cavity internal region. A processing step of processing to reduce the size in the region near the end face of the laser resonator; and a first conductive type clad layer, an active layer, and a second conductive type on the first conductive type substrate processed by the processing step. A step of sequentially epitaxially growing a cladding layer and a second conductivity type protection layer; a step of selectively forming a dielectric film on the second conductivity type protection layer; and the dielectric film, the epitaxially grown layer, and Annealing the substrate, wherein the annealing step generates holes under the dielectric film, and diffuses the holes until reaching the active layer. The band gap of the vessel edge surface vicinity region, a method of manufacturing a semiconductor laser device characterized by being larger than the band gap of the inner region of the laser resonator. 8. In the processing step, one principal surface of the substrate in the laser cavity inner region is (10) using a substrate inclined within a range of 0 degree or more and less than 5 degrees from the (100) plane.
8. The method for manufacturing a semiconductor laser device according to claim 7, wherein the semiconductor laser device is processed so as to be inclined within a range from 5 degrees to 15 degrees from the 0) plane. 9. In the processing step, one principal surface of the substrate in the region near the laser cavity end face is (1) using a substrate inclined within a range of 5 ° to 15 ° from the (100) plane.
8. The method for manufacturing a semiconductor laser device according to claim 7, wherein the semiconductor laser device is processed so as to be inclined within a range from 0 degree to less than 5 degrees from the (00) plane. 10. The method according to claim 7, wherein the processing step includes a step of forming a resist mask selectively inclined on the substrate, and a step of isotropically etching the resist mask and the substrate. 10. The method for manufacturing a semiconductor laser device according to any one of claims 1 to 9.