JP2003332691A - Semiconductor laser element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser element and its manufacturing method in which the ratio of the vertical emission angle relative to the horizontal emission angle of laser light can be brought close to 1 and current vs optical output characteristics exhibiting excellent linearity can be attained without causing a kink phenomenon to a high output. <P>SOLUTION: A lower clad layer 101, an active layer 102, a first upper clad layer 103, a first etching stop layer 104, a second upper clad layer 105, a second etching stop layer 106, a P third upper clad layer 107, a third etching stop layer 108, a fourth upper clad layer 109, a bad gap layer 110, and a cap layer 111 are formed sequentially on a substrate 100. A ridge stripe layer 150 is formed of the second upper clad layer 105 through the fourth upper clad layer 109. <P>COPYRIGHT: (C)2004,JPO

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 and a method for manufacturing the same, and more particularly to a semiconductor laser device used for a light source such as an optical disk and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a semiconductor laser device, there is a semiconductor laser device for an edge emitting type optical disk. In this semiconductor laser device, the light divergence angle (vertical radiation angle) in the direction perpendicular to the substrate surface is usually larger than the light divergence angle (horizontal radiation angle) in the horizontal direction. When this semiconductor laser device is used for an optical disc, if the vertical radiation angle and the horizontal radiation angle are the same, a sufficient amount of light can be obtained without shaping the light beam.
Actually, since the light beam is shaped or a part of the light beam is cut, there is a problem that a sufficient light amount cannot be obtained.

The simplest method for solving such a problem is to narrow the width of the light emitting portion to the same extent as the vertical spread of the light emitting region and widen the horizontal radiation angle. However, the ridge stripe structure that is usually adopted (the structure in which the periphery of the stripe is etched so that the cross-sectional shape when viewed from the light emitting end face of the stripe that serves as an optical waveguide is a convex portion) has a shape in which the skirt of the ridge cross section is widened. For,
It is difficult to widen the horizontal emission angle by narrowing the width of the light emitting portion to the same extent as the vertical extension of the light emitting region. Also, as a semiconductor laser device having a structure other than the ridge stripe structure, there is one in which a regrowth interface of a semiconductor crystal is provided in the vicinity of an active layer, but in that case, deterioration progresses from the regrowth interface, so that sufficient reliability is obtained. There is a problem that you cannot get it.

As an example of a conventional semiconductor laser device, there is a ridge structure described in Japanese Patent Application Laid-Open No. 6-216462. As shown in FIG. 10, this semiconductor laser device comprises a first cladding layer 2 (n-Al _0.4 Ga _0.6 As) and an active layer 3 (un-Al _0.1 Ga) on a substrate 1 made of n-type GaAs.
_0.9 As), second cladding layer 4 (p-Al _0.4 Ga _0.6 As), etching stop layer 5 (p-Al _0.2 Ga _0.8 As), ridge shape adjusting layer 6 (p-Al _x Ga _{1 -x} As, x Gradually decreases), the third
Clad layer 7 (p-Al _0.4 Ga _0.6 As), cap layer 8 (p
-GaAs) is formed. The Al mixed crystal ratio x in the semiconductor laser device has the distribution shown in FIG.
In the semiconductor laser device shown in FIG. 10, in order to form a striped ridge, the ridge shape adjusting layer 6 is set to 0.2 μm using the Si ₃ N ₄ layer (not shown) as a mask for the first etching.
It is performed under the condition of leaving about m. Subsequently, the second etching is performed using an etchant of HCl: H ₂ = 1: 1 to remove the remaining portion of the ridge shape adjusting layer 6. In such an etchant, since the etching rate becomes larger for the layer having a large Al mixed crystal ratio x, the etching of the portion near the etching stop layer 5 further progresses, and the side surface of the ridge shape adjusting layer 6 becomes nearly vertical. In FIG. 10, 9 is an n-GaAs current blocking layer, and 10 is a p-GaAs contact layer.

The ridge structure of the semiconductor laser device shown in FIG. 10 utilizes the difference in etching rate depending on the Al mixed crystal ratio. However, when a layer having an extremely different mixed crystal ratio is used, the refractive index varies depending on the mixed crystal ratio. Since they are different, they affect the optical confinement of the semiconductor laser device. That is, since it is necessary to set the mixed crystal ratio x near the etching stop layer to be high, the light emission angle in the vertical direction widens, and the ellipticity (vertical radiation angle / horizontal radiation angle It is not suitable for reducing the radiation angle in the direction. When the ridge portion is formed by wet etching, the side surface of the ridge portion approaches a crystal plane orientation with a slow etching rate as time passes, but is close to, for example, a (111) plane of a crystal with a slow etching rate. If the surface is taken as the side surface of the ridge portion, the (111) side surface of the ridge portion is formed even if the Al mixed crystal ratio is different.
Since the deviation from the plane orientation is slight, the effect of making the average inclination of the side surface of the ridge portion (the overall inclined shape of the plurality of different inclined surfaces) closer to vertical is not sufficient.

Therefore, an object of the present invention is to make the ratio of the vertical radiation angle to the horizontal radiation angle of the laser light close to 1, and to obtain a current-to-light output excellent in linearity without causing a kink phenomenon up to a high output. It is an object of the present invention to provide a semiconductor laser device having characteristics and a manufacturing method thereof.

[0007]

In order to achieve the above object, a semiconductor laser device of the present invention comprises a lower clad layer of a first conductivity type, an active layer, and a first upper clad layer of a second conductivity type on a substrate. A combination of N-1 pieces (N is an integer of 3 or more) from the first etching stop layer to the N-1th upper cladding layer of the second conductivity type and the N-1th etching stop layer;
The semiconductor laser device has a laminated structure of semiconductor laser devices in which upper clad layers are sequentially formed, and has a ridge stripe portion formed of layers from a second upper clad layer to an Nth upper clad layer.

According to the semiconductor laser device having the above structure, it becomes possible to make the average inclination of the side surface of the ridge stripe portion close to perpendicular to the substrate plane. Here, the average inclination means an inclined shape as a whole of a plurality of different inclined surfaces. Hereinafter, this principle will be described with reference to FIGS. 8 (a) and 8 (b).

FIG. 8A is a schematic view of a left side surface of a ridge in a cross section of a conventional semiconductor laser device. As shown in FIG. 8 (a), an etching stop layer 60 and a second upper cladding layer 70 are formed on a semiconductor substrate (not shown) having a (100) plane, and the side surface of the semiconductor substrate is flat by dry etching or the like. An etching shape 80 perpendicular to the is formed. Subsequently, wet etching is performed. At this time, the etching rate is high at (011), intermediate at (100), and (1
It will be the slowest in 11). The etching shape 80 progresses to 81, 82, 83 with the passage of time. As time passes, the side surface of the ridge stripe portion approaches the plane orientation with the slowest etching rate, in this case (111).

FIG. 8B is a schematic view of the ridge left side surface of the cross section of the semiconductor laser device of the present invention. As shown in FIG. 8B, a first etching stop layer 61, a second upper clad layer 71, a second etching stop layer 62, and a third upper clad layer 72 are formed, and side surfaces are vertically etched by dry etching or the like. A shape 90 is formed. Since the side surface of the second etching stop layer 62 is etched first, the (111) planes 91b, 92b, 93b are formed in the third upper cladding layer 72 with this layer as a starting point over time,
The (111) plane 9 is formed on the second upper cladding layer 71 with the passage of time.
1a, 92a, 93a are formed. By separating the upper clad layer in this way, a convex portion is formed in the middle of the side surface of the ridge stripe portion, and as a result, the lateral etching amount on the ridge upper portion can be reduced, and on average, the ridge stripe is closer to vertical. The side of the part is obtained.

Therefore, the average inclination of the side surfaces of the ridge stripe portion can be made closer to the vertical to the substrate plane ((ridge lower width-ridge upper width) / ridge height closer to zero). In addition, by forming a ridge stripe portion having a side surface that is almost perpendicular to the substrate plane,
The width of the lower part of the ridge can be narrowed and the horizontal radiation angle corresponding to it can be widened. Further, by forming a ridge stripe portion having a side surface that is nearly perpendicular to the plane of the substrate, the ridge height can be increased, and the vertical radiation angle corresponding to it can be narrowed. Therefore, the ellipticity (vertical emission angle / horizontal emission angle) of laser light is 1
Can be approached to. In addition, by forming a ridge stripe portion having a side surface that is nearly perpendicular to the substrate plane, the ridge top width does not have to be made too narrow even if the ridge height is increased, so an increase in electrical resistance there is suppressed. , The operating voltage can be kept low. Further, since the width of the lower portion of the ridge can be narrowed, a kink phenomenon does not occur even at a higher output, and current-optical output characteristics having excellent linearity can be obtained.

The semiconductor laser device of one embodiment is
The second upper clad layer among the clad layers from the second upper clad layer to the Nth upper clad layer is the thickest semiconductor laser device.

This will be described with reference to the schematic view of the left side surface of the ridge in the cross section of the semiconductor laser device shown in FIG. As shown in FIG. 9, the first etching stop layer 63, the second upper cladding layer 73, the second etching stop layer 64, the third upper cladding layer 74, the third etching stop layer 65, and the fourth
There is an upper cladding layer 75 and a cap layer 66. An etching shape 95 with vertical side surfaces is formed by dry etching or the like. Wet etching continues, but at that time
When the (111) plane is exposed, etching is completely stopped. Then, the (111) planes 96a, 96b, 96c appear and the etching is stopped. At this time, in order to make the maximum of the lateral etching lengths 73x1, 74x, and 75x the smallest, these three may be made equal. For that purpose, the side surface of the etching shape 95 is made different by each etching stop layer. Length 73 so that it is evenly divided
It suffices that y1, 74y, and 75y are equal. On the other hand, the remaining thickness 73y2 of the second upper cladding layer 73 determines the lateral length 73x2 of the ridge hem. From the above, the second
The thickness of the upper clad layer 73 may be (73y1 + 73y2), and if 73y2 is not zero, the thickness of the second upper clad layer 73 is larger than the thickness of the third and fourth upper clad layers 74 and 75. Become. From the above consideration, the second upper cladding layer 7
When 3 is thicker than the third to Nth clad layers (fourth upper clad layer 75 in FIG. 9), the shape of the side surface of the ridge stripe portion becomes closer to vertical in average. Therefore, it is possible to realize a semiconductor laser device in which the ellipticity is close to 1, the operating voltage is low, and the kink phenomenon does not occur even at high output.

The semiconductor laser device of one embodiment is
The constituent elements of the respective etching stop layers from the first etching stop layer to the (N-1) th etching stop layer are the same. Thereby, each etching stop layer can be removed in the same etching step, or conversely, the etching stop effect can be utilized in the same etching step, and the etching step can be simplified.

The semiconductor laser device of one embodiment is
Each etching stop layer from the first etching stop layer to the (N-1) th etching stop layer is made of GaInP, and each cladding layer and the lower cladding layer from the first upper clad layer to the Nth upper clad layer are made of AlGaInP. It is a semiconductor laser device. With such a material system, a laser that oscillates in the wavelength range of 630 nm to 680 nm can be manufactured. By using GaInP as the etching stop layer, unlike AlGaInP, which is the material of the clad, does not contain Al, so that the etching rate ratio between each upper clad layer and the etching stop layer can be made sufficiently large. In addition, in this material system, (1
When an inclined substrate tilted from the (00) plane in the [011] direction by about 0 ° to 20 ° is used and the cleavage surface is used as the light emitting surface, the ridge stripe direction is the [0-11] direction, and thus the ridge stripe portion The (111) A plane is likely to appear on the side surface, and the upper portion of each upper cladding layer has a narrowed shape. When a specific plane orientation appears in this way, the vertical ridge forming method using the semiconductor laser device of the present invention is particularly effective. The thickness of each etching stop layer is 200 Å or less, which has a quantum effect, and _{y of} Gay In _1-y P is 0.5 <
By applying tensile strain with y ≦ 1, it is possible to avoid absorption of laser light having a band gap of the active layer that is substantially equal to that of the active layer.

The semiconductor laser device of one embodiment is
A semiconductor in which the etching stop layers from the first etching stop layer to the (N-1) th etching stop layer are made of GaAs, and the cladding layers from the first upper clad layer to the Nth upper clad layer and the lower clad layer are made of AlGaAs. It is a laser device. In such a material system, the active layer is made of AlGaAs, GaAs or InGaAs, so that wavelengths of 780 nm band, 810 nm band and 860 n band are obtained, for example.
A laser that oscillates in the m band or the 980 nm band can be manufactured. GaAs is AlGaA that is the material of the clad.
Unlike s, since Al is not included, the etching rate ratio between each upper cladding layer and the etching stop layer can be increased. In addition, in this material system, the main surface is generally (1
A (00) plane just substrate is often used, and in that case, the ridge stripe direction is [0-11] direction,
11] direction. In the [0-11] direction, like the AlGaInP system, the (111) A plane is likely to appear on the side surface of the ridge stripe portion, and the upper portion of each upper cladding layer is narrowed. On the other hand, [011]
The (111) B plane is likely to appear at the bottom of each upper clad layer when oriented in the direction, but if the etching time is lengthened, the (111) A plane having the slowest etching rate at the top of each upper clad layer is formed.
The surface may appear. When a specific plane orientation appears in this way, the vertical ridge forming method using the semiconductor laser device of the present invention is particularly effective. By setting the thickness of each etching stop layer to 200 Å or less, which has a quantum effect, it is possible to avoid absorption of a laser in the etching stop layer, which is approximately equal to the band gap of the active layer.

The semiconductor laser device of one embodiment is
The side surface side of each etching stop layer from the second etching stop layer to the (N-1) th etching stop layer of the ridge stripe portion projects laterally, and the upper clad layers near the side surface side of each etching stop layer laterally. It is a semiconductor laser device protruding to the outside. With such a shape, even if the inclination of each upper cladding layer is slanted in normal etching, the average slant can be made close to perpendicular to the substrate plane.

The semiconductor laser device of one embodiment is
The semiconductor laser device has a dielectric film formed so as to cover at least the side surface of the ridge stripe portion. As described above, by covering the side surface of the ridge stripe portion with the dielectric film, a semiconductor laser device having good characteristics can be obtained by a simple process. Particularly when the side surface of the ridge stripe portion is not smooth as in the present invention, the step coverage (step coverag) as in the plasma CVD method is used.
e; good protection effect can be obtained by using a film forming method with good step coverage.

The semiconductor laser device of one embodiment is
The semiconductor laser device has a void formed between the side surface of the ridge stripe portion and the dielectric film. Since this void has a low refractive index, it increases the difference in refractive index between the inside and side surfaces of the ridge stripe portion, and collects light in the central portion of the ridge away from the side surface of the ridge stripe portion, increasing the horizontal radiation angle. There is.

Further, in the method for manufacturing a semiconductor laser device according to one embodiment, a compound semiconductor layer serving as a current blocking layer of the same conductivity type as the lower cladding layer is formed so as to cover at least the side surface of the ridge stripe portion. It is a semiconductor laser device. As described above, by covering the side surface of the ridge stripe portion with the compound semiconductor layer, the side surface is protected and a semiconductor laser device having good reliability can be obtained. In particular, even when the side surface of the ridge stripe portion is not smooth as in the present invention, it is possible to form a good film on the side surface by utilizing surface migration during crystal growth, and to prevent deterioration from the side surface of the ridge stripe portion. It can be prevented.

The semiconductor laser device of one embodiment is
In the semiconductor laser device, a void is formed between the side surface of the ridge stripe portion and the current blocking layer. Since this void has a low refractive index, it increases the difference in refractive index between the inside and side surfaces of the ridge stripe portion, and collects light in the central portion of the ridge away from the side surface of the ridge stripe portion, increasing the horizontal radiation angle. There is.

Further, according to the method of manufacturing a semiconductor laser device of the present invention, the first conductivity type lower clad layer, the active layer, the second conductivity type first upper clad layer, the first etching stop layer, and the first etching stop layer are formed on the substrate. 2nd conductivity type N-1 upper clad layer, Nth
-1 N-1 combination (N is an integer of 3 or more) up to the etching stop layer and the Nth upper cladding layer are sequentially formed, and an etching mask is formed on the Nth upper cladding layer in the region where the ridge stripe portion is formed. And a region not covered by the etching mask of each layer from the N-th upper cladding layer to the second etching stop layer by the first etching step and a region not covered by the etching mask of the second upper cladding layer. Is partially etched, and a region of the second upper etching stop layer which is not covered by the etching mask is etched by the second etching until the first etching stop layer is exposed.

By this manufacturing method, it is possible to easily manufacture a semiconductor laser device in which the average inclination of the side surface of the ridge stripe portion is reduced. Therefore, it is possible to realize a semiconductor laser device in which the ratio of the vertical emission angle to the horizontal emission angle of the laser light can be brought close to 1 and the current-optical output characteristic excellent in linearity can be obtained without causing the kink phenomenon even at a high output. it can.

In the method for manufacturing a semiconductor laser device according to one embodiment, in the first etching step, the etching stop layers from the second etching stop layer to the (N-1) th etching stop layer are etched. In the second etching step, etching with a low etching rate for maintaining an etching stop effect on each of the etching stop layers from the second etching stop layer to the N-1th etching stop layer and the first etching stop layer is used. It is a method of manufacturing a semiconductor laser device using the method. In order to make the average inclination of the side surfaces of the second etching stop layer to the (N-1) th etching stop layer close to perpendicular to the substrate plane by using two kinds of etching methods having different actions for the etching stop layer in this procedure. Can be used for.

In the method of manufacturing a semiconductor laser device according to one embodiment, dry etching or a combination of dry etching and wet etching is used in the first etching step, and wet etching is used in the second etching step. It is a method of manufacturing a semiconductor laser device. In the first etching step,
Dry etching is suitable as a method for simultaneously etching each etching stop layer and each upper cladding layer. In addition, it is useful to use wet etching together to remove the damaged layer of dry etching.
On the other hand, in the second etching step, the etching stop effect of dry etching is insufficient, so
Wet etching is effective for exposing the etching stop layer.

According to the method of manufacturing a semiconductor laser device of one embodiment, in the manufacturing of a semiconductor laser device having an AlGaInP clad, a semiconductor is wet-etched with a phosphoric acid-based or hydrochloric acid-based etchant in the second etching step. It is a method of manufacturing a laser element. Since these etchants have a large etching rate ratio between the AlGaInP clad layer and the GaInP etching stop layer, the etching of each upper clad layer can be favorably performed while maintaining the etching stop effect of each etching stop layer.

In the method for manufacturing a semiconductor laser device according to one embodiment, in the manufacture of a semiconductor laser device having an AlGaAs-based cladding, a semiconductor is wet-etched with a hydrofluoric acid-based or hydrochloric acid-based etchant in the second etching step. It is a method of manufacturing a laser element.
These etchants consist of AlGaAs cladding layers and GaAs.
s Since the ratio of the etching rate to the etching stop layer is large, the etching of each upper clad layer can be favorably performed while maintaining the etching stop effect of each etching stop layer.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION A semiconductor laser device and a method for manufacturing the same according to the present invention will be described in detail below with reference to the embodiments shown in the drawings. In the following embodiment, (Al _x Ga
_1-x ) _y In _1-y P (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) to AlGaIn
P, Ga _y In _1-y P (0 ≦ y ≦ 1) is GaInP, Al _x Ga _1-x
As (0 ≦ x ≦ 1) may be described as AlGaAs. In addition, in this embodiment, the first conductivity type is n-type and the second conductivity type is p-type.

[First Embodiment] FIG. 1 is a sectional view showing the device structure of a semiconductor laser device according to the first embodiment of the present invention. This semiconductor laser device, as shown in FIG.
GaAs substrate (15 ° off in [011] direction from (100))
N-AlGaInP lower cladding layer 101 on 100,
An active layer 102 in which undoped quantum wells and barrier layers are alternately stacked, and a p-AlGaInP first upper cladding layer 103.
And a p-GaInP first etching stop layer 104,
p-AlGaInP second upper cladding layer 105, p-GaI
nP second etching stop layer 106 and p-AlGaIn
P third upper cladding layer 107, p-GaInP third etching stop layer 108, p-AlGaInP fourth upper cladding layer 109, p-GaInP intermediate bandgap layer 1
10 and a p-GaAs cap layer 111 are sequentially formed. In addition, the ridge stripe portion 1 including the layers from the second upper clad layer 105 to the fourth upper clad layer 109 described above.
Forming 50.

The side surface shape of the ridge stripe portion 150 has the second and third etching stop layers 106 and 10.
8 protrudes from the side surface, and the cross sections of the second, third, and fourth upper cladding layers 105, 107, and 109 have a trapezoidal shape in which the bottom is wider and the width is narrower toward the top.

The above second and third etching stop layers 10
6, 108 side surfaces and the third and fourth upper cladding layers 107, 10
An n-AlInP current blocking layer 120 is formed on the side surface of the electrode 9. Further, the contact layer 121 is formed on the current blocking layer 120 and the cap layer 111, and the p-side electrode 123 is formed on the contact layer 121. Further, an n-side electrode 122 is formed on the back surface side of the n-GaAs substrate 100. The side surfaces of the second upper cladding layer 105, the third upper cladding layer 107 and the fourth upper cladding layer 109 of the ridge stripe portion 150 and the current blocking layer 1 are formed.
Voids (vacuum or gas regions) 119 are formed between them and 20 respectively.

The ridge stripe portion 150 has a lower width of 1.8 μm and a ridge height of 1.9 μm. The thinnest portion of the ridge is the interface between the third upper cladding layer 107 and the intermediate bandgap layer 110, and has a width of 1.1 μm.
It has become m.

According to the semiconductor laser device of the first embodiment, the side surface of the ridge stripe portion 150 has an average inclination.
(Inclined shape as a whole of a plurality of different inclined surfaces)
By making the height of the ridge high and narrowing the width of the lower portion of the ridge by making it possible to approach the plane of the aAs substrate 100 perpendicularly, the ratio (ellipticity) of the vertical emission angle to the horizontal emission angle of the laser light can be increased. Since the ridge width can be reduced to 1 and the ridge width can be narrowed, a current-light output characteristic having excellent linearity can be obtained without causing a kink phenomenon even at a higher output.

The first etching stop layer 10 is also used.
By making the film thickness of the second upper clad layer 105 immediately above the fourth clad layer 105 thicker than the respective upper clad layers above it, the average inclination of the side surfaces of the ridge stripe portion 150 can be made closer to flat.

The first etching stop layer 10 is also used.
Since the constituent elements of each of the etching stop layers from 4 to the third etching stop layer 108 are the same, each etching stop layer is removed in the same etching step, or conversely, the etching stop effect is utilized in the same etching step. be able to.

Further, since each GaInP etching stop layer does not contain Al unlike each AlGaInP upper clad layer, the etching rate ratio between the upper clad layer and the etching stop layer can be increased.

Further, since the etching stop layer and the upper clad layer of the ridge stripe portion 150 have a laterally protruding shape, even if the upper clad layers are inclined in a normal etching, the average The vertical inclination can be made close to perpendicular to the plane of the n-GaAs substrate 100.

The side surface of the ridge stripe portion 150 is formed on the side surface of the n-AlInP current blocking layer 12 which is a compound semiconductor layer.
By covering with 0, the side surface of the ridge stripe portion 150 is protected, and a semiconductor laser device having good reliability can be obtained.

Further, since the void 119 formed on the side surface of the ridge stripe portion 150 has a low refractive index, the difference in the refractive index between the inside and the side surface of the ridge stripe portion 150 is increased, and the light is reflected on the side surface of the ridge stripe portion 150. The radiation angle in the horizontal direction can be increased by collecting them in the central part of the ridge away from.

Next, a method of manufacturing the semiconductor laser device of the first embodiment will be described. 2 (a), 2 (b) and 3
(a), (b) is sectional drawing in the manufacturing process of a semiconductor laser element. As shown in FIG. 2A, the n-GaAs substrate 100
In addition, n- (Al _0.7 ) was obtained by the MBE method (molecular beam epitaxy method).
Ga _0.3 ) _0.5 In _0.5 P Lower cladding layer 101 (thickness 1.5 μ
m, carrier concentration 1 × 10 ¹⁸ cm ⁻³ ), three undoped GaInP layers (thickness 6 nm) and four undoped (Al _0.5
Ga _0.5 ) _0.5 In _{0.5 The} active layer 102 sandwiched between P layers, p- (Al
_0.7 Ga _0.3 ) _0.5 In _0.5 P First upper cladding layer 103 (0.2
μm, 1.0 × 10 ¹⁸ cm ⁻³ ), p-Ga _0.6 In _0.4 P first
Etching stop layer 104 (8 nm, 1.0 × 10 ¹⁸ c
m ^-3 ), p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P second upper cladding layer 105 (0.7 μm, 1.3 × 10 ¹⁸ cm ^-3 ), p-Ga
_0.6 In _0.4 P second etching stop layer 106 (8 nm,
1.0 × 10 ¹⁸ cm ^-3 ), p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5
P 3rd upper clad layer 107 (0.6 μm, 1.3 × 10 ¹⁸
cm ^-3 ), p-Ga _0.6 In _0.4 P third etching stop layer 108 (8 nm, 1.0 × 10 ¹⁸ cm ^-3 ), p- (Al _0.7
Ga _0.3 ) _0.5 In _0.5 P Fourth upper cladding layer 109 (0.6 μ)
m, 1.3 × 10 ¹⁸ cm ⁻³ ), p-GaInP intermediate bandgap layer 110 (0.15 μm, 3 × 10 ¹⁸ cm ⁻³ ) p−
GaAs cap layer 111 (0.3 μm, 3 × 10 ¹⁸ c
m ^-3 ) are sequentially formed. At this time, the n-type dopant is Si
And the p-type dopant is Be. An SiO ₂ mask 112 as an example of an etching mask is formed thereon so that the stripes (depth direction in the drawing) are in the [01-1] direction.

Next, as shown in FIG. 2 (b), the SiO ₂
Cl is used as the first etching step using the mask 112.
ICP (Inductiv) by plasma mixed with system gas and Ar
ely Coupled Plasma) The remaining thickness of the second upper cladding layer 105 is 0.4 by dry etching.
The cap layer 111, the intermediate bandgap layer 110, the fourth upper clad layer 109, the third etching stop layer 108, the third upper clad layer 107, the second etching stop layer 106, and the second upper clad layer 105 so as to have a thickness of 5 μm.
And etching with saturated bromine water to a depth of 0.1 μm.

Next, as shown in FIG. 3 (a), the SiO ₂ mask 112 (shown in FIG. 2 (b)) is removed with buffered hydrofluoric acid, and the remaining first portion is removed with phosphoric acid as a second etching step. 2 The upper clad layer 105 is etched until the first etching stop layer 104 is exposed to form the ridge stripe portion 1
Form 50. At this time, since the first etching stop layer 104 has an extremely low etching rate with respect to phosphoric acid, it functions as an etching stop layer and the p-type first upper cladding layer 103 is not etched. Second,
The third and fourth upper cladding layers 105, 107 and 109 are (11
1) Since the etching rate of surface A is the slowest,
1) A slope close to plane A is formed, and the substrate 100 is (100)
Since the substrate has a surface inclined from the surface, the inclination of the side surface of the ridge stripe portion 150 is different between left and right.

Next, as shown in FIG. 3 (b), the side surfaces of the ridge stripe portion 150, the n-type Al _{0. 5} In _0.5 P current blocking layer 120 is formed by the MBE method. At this time, voids 119 are formed below the side surfaces of the second and third etching stop layers 106 and 108 and the intermediate bandgap layer 110, which will be the protrusions, respectively. The void 119 has an effect of increasing the difference in refractive index between the ridge stripe portion 150 and the outside and strengthening light confinement. In addition, the void 119
Can be eliminated depending on the growth conditions.

Then, as shown in FIG. 1, a p-type GaAs contact layer 121 (thickness: 4 μm) is formed on the entire surface, and an n-side electrode 122 and a p-side electrode 123 are formed. Next, although not shown, the laser wafer is cleaved to coat a low reflectance reflective film on the end face of the light emitting portion and a high reflectance reflective film on the end face opposite to the light emitting portion.

A laser wafer manufactured by the method for manufacturing a semiconductor laser device described above is divided into chips, mounted on a stem, and a characteristic is examined by applying a current. As a result, an optical output of 3 m is obtained.
At W, horizontal radiation angle 12 °, vertical radiation angle 18 °, ellipticity 1.
5 was obtained. Also, the operating voltage is 60 mW of optical output and 2.
It was 5V. The operating voltage is mainly determined by the width of the narrowest portion of the ridge stripe portion 150. In the present invention, the width of the narrowest portion of the ridge stripe portion 150 is 1. 9 although the ridge height is as high as 1.9 μm. Since it is relatively wide at 1 μm, the rise in operating voltage is suppressed.

Although the ICP dry etching is used in the first embodiment, the ECR (Electron Cyclotron) is used.
Resonance) dry etching and RIE (Reactive Ion)
Etching; reactive ion etching) or the like may be used. The saturated bromine water etching after dry etching may be hydrochloric acid-based or sulfuric acid-based etching, or this step may be omitted.

Further, in the first embodiment, the dry etching is performed up to the middle of the second upper cladding layer 105. However, for example, the dry etching is performed up to the middle of the third upper cladding layer 107, and the remaining etching is performed by the etching stop layer. Alternatively, wet etching for etching 104, 106 and 108 may be performed. Moreover, the etching stop layers 104, 106, 108 are not used at all.
Wet etching may be performed with an etchant for etching.

In the first embodiment, the second and third etching stop layers 106 and 108 are projected on the side surface of the ridge stripe portion 150. However, in order to reduce the projection, the second and third etching stop layers 106 and 108 are formed after the side surface of the ridge stripe portion is formed. Two,
An etching process of the third etching stop layers 106 and 108 may be added.

The n-GaAs substrate 100 is a 15 ° off substrate, but the off angle of about 0 ° to 20 ° is Al.
It is suitable for GaInP laser.

As a method of growing the compound semiconductor layer,
In addition to the MBE method, MOCVD method (metal organic chemical vapor deposition method) or the like can be used.

By the method for manufacturing a semiconductor laser device according to the first embodiment, it is possible to easily manufacture a semiconductor laser device in which the average inclination of the side surfaces of the ridge stripe portion 150 is reduced.

Further, by sequentially using the two types of etching, the average inclination of the side surfaces of the ridge stripe portion 150 can be made closer to vertical.

In the first etching step, dry etching is suitable as a method for simultaneously etching each etching stop layer and each upper cladding layer.
In addition, it is useful to use wet etching together to remove the damaged layer of dry etching. On the other hand, in the second etching step, since the etching stop effect of dry etching is insufficient, wet etching is effective for exposing the first etching stop layer.

By using wet etching with phosphoric acid as the second etching step, AlGa
Since the ratio of the etching rates of the InP clad layer and the GaInP etching stop layer is large, each upper clad layer can be satisfactorily etched while maintaining the etching stop effect of each etching stop layer. Although wet etching with phosphoric acid was performed in the second etching step, the present invention is not limited to this, and wet etching with a phosphoric acid-based or hydrochloric acid-based etchant may be performed.

According to the semiconductor laser device and the method of manufacturing the same of the present invention, the window structure in which the active layer on the light emitting end face is mixed and the active layer on the light emitting end face are covered with the compound semiconductor crystal having a larger energy band gap. By combining with a window structure, higher output can be achieved. In the high-power semiconductor laser device, by bringing the ellipticity, which is the effect of the present invention, close to 1, the light utilization efficiency can be increased and the effective utilization light output can be increased.

In the first embodiment, the active layer 10
On the second layer, three combinations of the first upper cladding layer 103, the first etching stop layer 104 to the third upper cladding layer 107, the third etching stop layer 108, and the fourth
The upper clad layer 109 was sequentially formed, but N-1 pieces (N is 3 or 5 or more) from the first upper clad layer, the first etching stop layer to the N-1th upper clad layer, the N-1th etching stop layer. The present invention may be applied to a semiconductor laser device in which the Nth upper clad layer is sequentially formed.

[Second Embodiment] FIG. 4 is a sectional view showing the device structure of a semiconductor laser device according to a second embodiment of the present invention. This semiconductor laser device has an n-
GaAs substrate (15 ° off from (100) in [011] direction)
N-AlGaInP lower clad layer 201 on 200,
An active layer 202 in which undoped quantum wells and barrier layers are alternately stacked, and a p-AlGaInP first upper cladding layer 203.
And a p-GaInP first etching stop layer 204,
p-AlGaInP second upper cladding layer 205, and p-GaI
nP second etching stop layer 206, p-AlGaIn
P third upper cladding layer 207, p-GaInP third etching stop layer 208, p-AlGaInP fourth upper cladding layer 209, p-GaInP intermediate bandgap layer 2
10 and a p-GaAs cap layer 211 are sequentially formed. A ridge stripe portion 25 including layers from the second upper clad layer 205 to the fourth upper clad layer 209.
Forming 0.

Regarding the side surface shape of the ridge stripe portion 250, the second and third etching stop layers 206 and 208 project from the side surfaces, and the second, third and fourth upper cladding layers 205, 207 and 209 are formed. However, it has a shape in which the bottom surface is wide and becomes narrower toward the top.

A SiO ₂ protective layer 220 is formed on the side surface of the ridge stripe portion 250 by a plasma CVD method,
An n-side electrode 222 is formed on the back surface side of the n-GaAs substrate 200, and a p-side electrode 223 is formed on the SiO ₂ protective layer 220. A void (vacuum or gas region) 219 is formed between the SiO ₂ protective layer 220 and the upper side surfaces of the second upper cladding layer 205, the third upper cladding layer 207, and the fourth upper cladding layer 209 of the ridge stripe portion 250. Are formed respectively.

Dummy ridges 251 and 252 through which no current flows are formed on both sides of the ridge stripe portion 250. This semiconductor laser device is intended for junction down mounting in which the ridge portion contacts the stem or submount, and at that time, the dummy ridge 2 is formed so that stress is not concentrated on the ridge stripe portion 250.
51,252 are provided.

In the second embodiment, except that the thickness of the first upper cladding layer 203 is made thicker than that of the first embodiment,
It has almost the same structure as the first growth in the first embodiment.

The protective layer on the side surface of the ridge stripe portion is not limited to the SiO ₂ layer, but may be a Si ₃ N ₄ layer or the like. This protective layer is formed by thermal CVD in addition to plasma CVD.
The method and the sputtering method can be preferably used.

According to the semiconductor laser device of the second embodiment, the average inclination of the side surface of the ridge stripe portion 250 can be made close to perpendicular to the plane of the n-GaAs substrate 200, and thereby the ridge height. The ratio of the vertical emission angle to the horizontal emission angle (ellipticity) of the laser light can be reduced by narrowing the width of the ridge and narrowing the width of the lower part of the ridge, and the ridge width can be made narrower. Current-to-optical output characteristics with excellent linearity can be obtained without occurrence.

The first etching stop layer 20 is also used.
By making the film thickness of the second upper clad layer 205 immediately above 4 thicker than the respective upper clad layers thereon, the average inclination of the side surfaces of the ridge stripe portion 205 can be made closer to flat.

The first etching stop layer 20 is also used.
Since the constituent elements of each of the etching stop layers from 4 to the third etching stop layer 208 are the same, each etching stop layer is removed in the same etching step, or conversely, the etching stop effect is utilized in the same etching step. be able to.

Since each GaInP etching stop layer does not contain Al unlike each AlGaInP upper cladding layer, the etching rate ratio between each upper cladding layer and the etching stop layer can be increased.

Further, since the etching stop layer and the upper clad layer of the ridge stripe portion 250 have a shape protruding laterally, even if the inclination of each upper clad layer is slanted in normal etching, the average The vertical inclination can be made close to perpendicular to the plane of the n-GaAs substrate 200.

Further, by covering the side surface of the ridge stripe portion 205 with the SiO ₂ protective layer 220 which is a dielectric film, a semiconductor laser device having good characteristics can be obtained by a simple process.

Since the void 219 formed on the side surface of the ridge stripe portion 250 has a low refractive index, the difference in the refractive index between the inside and the side surface of the ridge stripe portion 250 is increased to allow light to enter the side surface of the ridge stripe portion 250. It collects in the central part of the ridge away from and has the function of increasing the horizontal radiation angle.

In the second embodiment, the active layer 20 is used.
On the second layer, three combinations of the first upper cladding layer 203, the first etching stop layer 204 to the third upper cladding layer 207, the third etching stop layer 208, and the fourth
The upper clad layer 209 was sequentially formed, but N-1 pieces (N is 3 or 5 or more) from the first upper clad layer, the first etching stop layer to the N-1th upper clad layer, the N-1th etching stop layer. The present invention may be applied to a semiconductor laser device in which the Nth upper clad layer is sequentially formed.

[Third Embodiment] FIG. 5 is a sectional view showing the device structure of a semiconductor laser device according to a third embodiment of the present invention. This semiconductor laser device, as shown in FIG.
On the GaAs substrate 300, n-AlGaAs lower clad layer 3
01, an active layer 302 in which undoped quantum wells and barrier layers are alternately laminated, a p-AlGaAs first upper cladding layer 30
3. The p-GaAs etching stop layer 304 is sequentially formed. On the etching stop layer 304, p-
A ridge stripe portion 350 composed of the AlGaAs second upper cladding layer 305, the p-GaAs second etching stop layer 306, the p-AlGaAs third upper cladding layer 307, and the p-GaAs cap layer 308 is formed, and the ridge stripe portion 350 is formed. Dummy ridge 35 where no current flows to the left and right
1,352 are formed.

A SiO ₂ protective layer 320, which is a dielectric film, is formed on the side surface of the ridge stripe portion 350. Further, an n-side electrode 322 is formed on the back surface side of the n-GaAs substrate 300, and the p-side electrode 3 is formed on the SiO ₂ protective layer 320.
23 is formed. The p-side electrode 323 is the p-GaAs cap layer 30 on the ridge stripe portion 350.
8 is electrically connected.

According to the semiconductor laser device of the third embodiment, the average inclination of the side surfaces of the ridge stripe portion 350 can be made close to the vertical direction with respect to the plane of the n-GaAs substrate 300, whereby the ridge height can be increased. The ratio of the vertical emission angle to the horizontal emission angle (ellipticity) of the laser light can be reduced by narrowing the width of the ridge and narrowing the width of the lower part of the ridge, and the ridge width can be made narrower. Current-to-optical output characteristics with excellent linearity can be obtained without occurrence.

The first etching stop layer 30 is also used.
By making the film thickness of the second upper clad layer 305 immediately above the fourth upper clad layer 305 thicker than the upper clad layers above it, the average inclination of the side surfaces of the ridge stripe portion 350 can be made closer to flat.

The first etching stop layer 30 is also used.
Since the constituent elements of No. 4 and the second etching stop layer 306 are the same, each etching stop layer can be removed in the same etching step, or conversely, the etching stop effect can be utilized in the same etching step.

Further, since each GaAs etching stop layer does not contain Al unlike each AlGaAs upper cladding layer, the etching rate ratio between the upper cladding layer and the etching stop layer can be increased.

Further, since the etching stop layer and the upper clad layer of the ridge stripe portion 350 are laterally projected, even if the upper clad layers are inclined in a normal etching, the average The vertical inclination can be made close to perpendicular to the plane of the n-GaAs substrate 300.

Further, according to the method of manufacturing a semiconductor laser device of the present invention, at least the side surface of the ridge stripe portion is covered with the SiO ₂ protective layer 320 which is a dielectric film, so that a semiconductor laser device having good characteristics can be obtained by a simple process. can get.

Next, a method of manufacturing the semiconductor laser device according to the third embodiment will be described. 6 (a), 6 (b) and 7
FIG. 6A is a sectional view in a manufacturing process of a semiconductor laser device.

As shown in FIG. 6A, n-Al _0.5 G is deposited on the n-GaAs substrate 300 having a plane orientation (100) by the MBE method.
a _0.5 As lower clad layer 301 (thickness 1.7 μm, carrier concentration 1 × 10 ¹⁸ cm ⁻³ ), an active layer in which two undoped GaAs layers (thickness 8 nm) are sandwiched by three undoped Al _0.3 Ga _0.7 As layers 302, p-Al _0.5 Ga _0.5 As first upper cladding layer 303 (thickness 0.17 μm, 1.0 × 10 ¹⁸ cm ⁻³ ), p
-GaAs first etching stop layer 304 (3 nm, 1.
0 × 10 ¹⁸ cm ^-3 ), p-Al _0.5 Ga _0.5 As second upper cladding layer 305 (thickness 0.7 μm, 1.5 × 10 ¹⁸ cm ^-3 ), p
-GaAs second etching stop layer 306 (3 nm, 1.
5 × 10 ¹⁸ cm ^-3 ), p-Al _0.5 Ga _0.5 As third upper cladding layer 307 (thickness 0.6 μm, 1.5 × 10 ¹⁸ cm ^-3 ), p
-GaAs cap layer 308 (thickness 0.5 μm, 3 × 10 ¹⁸
cm ^-3 ) are sequentially formed. At this time, the n-type dopant is Si and the p-type dopant is Be. SiO ₂ as an example of an etching mask is formed on the cap layer 308.
The mask 332 has stripes (in the depth direction in the drawing) of [01
1] direction.

From above the SiO ₂ mask 332, as shown in FIG.
As shown in (b), in the first etching step, the ICP dry process is performed from the cap layer 308, the third upper cladding layer 307, the second etching stop layer 306 to the middle of the second upper cladding layer 305 (remaining thickness 0.4 μm). Etching is performed, and then the second upper cladding layer 305 is etched by 0.05 μm with a mixed solution of sulfuric acid / hydrogen peroxide solution / water. Above I
CP dry etching and the mixed solution of sulfuric acid / hydrogen peroxide water / water have a small difference in etching rate between GaAs and AlGaAs, and etching with sulfuric acid / hydrogen peroxide water / water is as small as 0.05 μm. Two
The etching stop layer 306 has almost no protrusion.

Next, as shown in FIG. 7, as a second etching step, the remaining second upper cladding layer 305 is etched with hydrofluoric acid until the first etching stop layer 304 is exposed to form the ridge stripe portion 350. Then, dummy ridges 351 and 352 through which current does not flow are formed on both sides of the ridge stripe portion 350. At this time, the etching rate of the second etching stop layer 306 made of GaAs with respect to hydrofluoric acid is extremely smaller than 1/10 or less than that of the second and third upper cladding layers 305, 307 made of AlGaAs. The second etching stop layer 306 projects from the side surface of the.

Then, as shown in FIG. 5, a SiO ₂ protective layer 320 is formed on the side surface of the ridge stripe portion 350.
An n-side electrode 322 is formed on the back surface side of the n-GaAs substrate 300, and a p-side electrode 323 is formed on the SiO ₂ protective layer 320. Next, although not shown, the laser wafer is cleaved, and coating is performed so that the light emitting portion end face has a reflectance of 12% and the end face opposite to the light emitting portion has a reflectance of 95%.

A laser wafer manufactured by the method for manufacturing a semiconductor laser device described above is divided into chips, mounted on a stem, and a characteristic is examined by applying a current. As a result, a wavelength of 786 is obtained.
No kink occurred up to a light output of 255 mW in nm. The horizontal radiation angle was 13 ° and the vertical radiation angle was 15 °, and an ellipticity of 1.15 was obtained. The width of the bottom of the ridge is 1.6μ.
m, ridge top width 1.4 μm, ridge height 1.3 μm
And the operating voltage at a light output of 120 mW is 2.4 V
Met. In the typical example of the conventional semiconductor laser device that does not use the second etching stop layer, the ellipticity is 1.8,
The operating voltage is about 2.7V.

By the method for manufacturing a semiconductor laser device according to the third embodiment, it is possible to easily manufacture a semiconductor laser device in which the average inclination of the side surface of the ridge stripe portion 350 is small.

Further, according to the method of manufacturing a semiconductor laser device of the present invention, the two types of etching are sequentially used so that the average inclination of the side surface of the ridge stripe portion 350 becomes closer to perpendicular to the plane of the n-GaAs substrate 300. be able to.

In the first etching step, dry etching is suitable as a method for simultaneously etching each etching stop layer and each upper cladding layer. In addition, it is useful to use wet etching together to remove the damaged layer of dry etching. on the other hand,
In the second etching step, since the etching stop effect of dry etching is insufficient, wet etching is effective for exposing the first etching stop layer 304.

By performing wet etching with hydrofluoric acid in the second etching step, since the ratio of the etching rates of the AlGaAs cladding layer and the GaAs etching stop layer is large, the etching stop effect of each etching stop layer is maintained. The upper clad layers can be etched well. Although wet etching with hydrofluoric acid was performed in the second etching step, the present invention is not limited to this, and wet etching with a hydrofluoric acid-based or hydrochloric acid-based etchant may be performed.

Although each layer of the compound semiconductor is formed by the MBE method in the third embodiment, it may be formed by the MOCVD method (metal organic chemical vapor deposition method).

Further, in the third embodiment, the active layer 302 is a laminated layer of AlGaAs, but In with In added is added.
By arranging the GaAs quantum well layer with a GaAs or AlGaAs barrier layer to form an active layer, the oscillation wavelength is, for example, 98.
It may be 0 nm.

In the third embodiment, the active layer 30 is used.
The second upper clad layer 303, the first etching stop layer 304, the second upper clad layer 305, the second etching stop layer 306 and the third upper clad layer 307 were sequentially formed on the second layer. N-1 upper clad layer (N is an integer of 4 or more) in combination from the first upper clad layer, the first etching stop layer to the N-1th upper clad layer, the N-1th etching stop layer The present invention may be applied to a semiconductor laser device in which the layers are sequentially formed.

In the above first to third embodiments, AlGaIn
Although the semiconductor laser device having the P-based and AlGaAs-based clads has been described, it goes without saying that the present invention may be applied to semiconductor laser devices having other configurations.

In the first to third embodiments, the first
Although the conductivity type is n-type and the second conductivity type is p-type, the present invention may be applied to a semiconductor laser device in which the first conductivity type is p-type and the second conductivity type is n-type.

[0094]

As is apparent from the above, according to the semiconductor laser device of the present invention, the average inclination of the side surfaces of the ridge stripe portion can be made closer to the vertical with respect to the substrate plane, and thereby the ridge height can be increased. Can be increased and the width of the lower part of the ridge can be reduced. With this ridge shape, the ratio of the vertical emission angle to the horizontal emission angle of the laser light (ellipticity) can be made close to 1, and the ridge width can be made narrower, so that kink phenomenon does not occur even at higher output and linearity is achieved. Excellent current-to-light output characteristics can be obtained.

Further, according to the method of manufacturing a semiconductor laser device of the present invention, it is possible to easily manufacture a semiconductor laser device in which the average inclination of the side surfaces of the ridge stripe portion is reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor laser device according to a first embodiment of the present invention.

FIGS. 2A and 2B are cross-sectional views of a manufacturing process of the semiconductor laser device.

3 (a) and 3 (b) are cross-sectional views of the manufacturing process of the semiconductor laser device following FIG. 2 (b).

FIG. 4 is a sectional view of a semiconductor laser device according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a semiconductor laser device according to a third embodiment of the present invention.

6 (a) and 6 (b) are sectional views of a manufacturing process of the semiconductor laser device.

FIG. 7 is a cross-sectional view of the manufacturing process of the semiconductor laser device, following FIG. 6 (b).

8 (a) and 8 (b) are explanatory views for explaining the principle of the present invention.

FIG. 9 is an explanatory diagram illustrating the principle of the present invention.

FIG. 10 is a sectional view of a conventional semiconductor laser device.

FIG. 11 is a diagram showing an Al mixed crystal ratio distribution in a conventional semiconductor laser device.

[Explanation of symbols]

100 ... n-GaAs substrate, 101 ... n-AlGaInP lower clad layer, 102 ... active layer, 103 ... p-AlGaInP first upper clad layer, 104 ... p-GaInP first etching stop layer, 105 ... p-AlGaInP second layer Upper cladding layer, 106 ... p-GaInP second etching stop layer, 107 ... p-AlGaInP third upper cladding layer, 108 ... p-GaInP third etching stop layer, 109 ... p-AlGaInP fourth upper cladding layer, 110 ... p-GaInP intermediate bandgap layer, 111 ... p-GaAs cap layer, 120 ... n-AlInP current blocking layer, 122 ... n-side electrode, 123 ... p-side electrode, 150 ... ridge stripe part, 200 ... n-GaAs substrate, 201 ... n-AlGaInP lower cladding layer, 202 ... active layer, 203 ... p-AlGaInP first upper cladding layer, 04 ... p-GaInP first etching stop layer, 205 ... p-AlGaInP second upper cladding layer, 206 ... p-GaInP second etching stop layer, 207 ... p-AlGaInP third upper cladding layer, 208 ... p-GaInP third cladding layer 3 etching stop layer, 209 ... p-AlGaInP fourth upper cladding layer, 210 ... p-GaInP intermediate bandgap layer, 211 ... p-GaAs cap layer, 220 ... SiO ₂ protective layer, 222 ... n side electrode, 223 ... p Side electrode, 250 ... Ridge stripe portion, 300 ... n-GaAs substrate, 301 ... n-AlGaAs lower clad layer, 302 ... Active layer, 303 ... p-AlGaAs first upper clad layer, 304 ... p-GaAs etching stop layer, 305 ... p-AlGaAs second upper cladding layer, 306 ... p-GaAs second etching stop layer, 307 ... p -AlGaAs third upper cladding layer, 308 ... p-GaAs cap layer, 320 ... SiO ₂ protective layer, 322 ... n-side electrode, 323 ... p-side electrode, 350 ... ridge stripe portion, 351, 352 ... dummy ridges.

Claims (15)

[Claims] 1. A lower clad layer of a first conductivity type, an active layer, a first upper clad layer of a second conductivity type, a first etching stop layer to a second conductivity type N-1 layer on a substrate. N-1 pieces up to the clad layer and the N-1th etching stop layer (N
Is an integer greater than or equal to 3) and an Nth upper cladding layer are sequentially formed, and a ridge stripe portion including layers from the second upper cladding layer to the Nth upper cladding layer is provided. A semiconductor laser device characterized by the above. 2. The semiconductor laser device according to claim 1, wherein the second upper clad layer is thickest among the clad layers from the second upper clad layer to the Nth upper clad layer. Semiconductor laser device. 3. The semiconductor laser device according to claim 1, wherein the constituent elements of each of the etching stop layers from the first etching stop layer to the (N−1) th etching stop layer are the same. element. 4. The semiconductor laser device according to claim 1, wherein each of the etching stop layers from the first etching stop layer to the (N-1) th etching stop layer is made of GaInP, and the first upper cladding layer to the Nth etching stop layer. Each of the clad layers up to the upper clad layer and the lower clad layer are made of AlGaIn.
A semiconductor laser device comprising P. 5. The semiconductor laser device according to claim 1, wherein each of the etching stop layers from the first etching stop layer to the (N−1) th etching stop layer is made of GaAs, and the first upper cladding layer to the Nth etching stop layer. A semiconductor laser device characterized in that each clad layer up to the upper clad layer and the lower clad layer are made of AlGaAs. 6. The semiconductor laser device according to claim 1, wherein a side surface side of each etching stop layer from the second etching stop layer to the (N−1) th etching stop layer of the ridge stripe portion is projected laterally, A semiconductor laser device, wherein a part of each clad layer from the second upper clad layer to the Nth upper clad layer near a side surface of the etching stop layer is projected laterally. 7. The semiconductor laser device according to claim 1, wherein a dielectric film is formed so as to cover at least a side surface of the ridge stripe portion. 8. The semiconductor laser device according to claim 7, wherein a void is formed between the side surface of the ridge stripe portion and the dielectric film. 9. The semiconductor laser device according to claim 1, wherein a current blocking layer made of a compound semiconductor of the same conductivity type as the lower cladding layer is formed so as to cover at least a side surface of the ridge stripe portion. Characteristic semiconductor laser device. 10. The semiconductor laser device according to claim 9, wherein a void is formed between a side surface of the ridge stripe portion and the current blocking layer. 11. A lower clad layer of the first conductivity type, an active layer, a first upper clad layer of the second conductivity type, a first etching stop layer, and an N-1th second conductivity type on a substrate. N-1 pieces up to the clad layer and the N-1th etching stop layer (N
Is an integer of 3 or more), a step of sequentially forming an Nth upper cladding layer, a step of forming an etching mask in a region where the ridge stripe portion is formed on the Nth upper cladding layer, and the Nth upper cladding layer. A region of each layer from the cladding layer to the second etching stop layer that is not covered by the etching mask is etched, and further, a portion of the region of the second upper cladding layer that is not covered by the etching mask is etched. And an etching step of etching a region of the second upper cladding layer, which is partially etched by the first etching step, not covered by the etching mask until the first etching stop layer is exposed. A method for manufacturing a semiconductor laser device, comprising: an etching step. 12. The method for manufacturing a semiconductor laser device according to claim 11, wherein each etching stop layer from the second etching stop layer to the (N−1) th etching stop layer is etched in the first etching step. Etching method is used, and in the second etching step, an etching method having a small etching rate for maintaining an etching stop effect for each of the etching stop layers from the first etching stop layer to the (N-1) th etching stop layer is used. A method of manufacturing a semiconductor laser device, comprising: 13. The method of manufacturing a semiconductor laser device according to claim 11, wherein in the first etching step, dry etching is used or dry etching and wet etching are used in combination, and the second etching step is used. 2. A method of manufacturing a semiconductor laser device, which comprises using wet etching. 14. The method of manufacturing a semiconductor laser device according to claim 11, wherein each of the etching stop layers from the first etching stop layer to the (N−1) th etching stop layer is made of GaInP. To the N-th upper clad layer and the lower clad layer are made of AlGaInP, and wet etching is performed with a phosphoric acid-based or hydrochloric acid-based etchant in the second etching step. Manufacturing method. 15. The method for manufacturing a semiconductor laser device according to claim 11, wherein each of the etching stop layers from the first etching stop layer to the (N−1) th etching stop layer is made of GaAs, and the first upper cladding layer is formed. To the N-th upper clad layer and the lower clad layer are made of AlGaAs, and the second etching step is wet etching with a hydrofluoric acid-based or hydrochloric acid-based etchant. Device manufacturing method.