JP2000091698A - Semiconductor laser element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser element having a structure in which heat generated from a semiconductor laser is released efficiently. SOLUTION: In a semiconductor laser element 1 provided with a first semiconductor laser element 3 and a second semiconductor laser element 4, adjacent to each other, formed on a semiconductor substrate 2, a separating groove 5 which is formed between the first semiconductor laser element 3 and the second semiconductor laser element 4 and further etching-formed to the middle of the semiconductor substrate 2, and an insulating layer 6 and a metal layer 7 formed in the separating groove 5 in order are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a CD (Compa)
ct Disk) and DVD (Digital Video)
o Disc) is a semiconductor laser device used for an optical pickup of an optical disk device, and particularly for a CD and a DV.
The present invention relates to a semiconductor laser device having two wavelengths for reproducing an optical disk for D with one optical pickup.

[0002]

2. Description of the Related Art In order to reduce the cost of an optical disk device for a CD or a DVD and to improve the usability, an optical disk device for reproducing recorded information of an optical disk for a CD and a DVD using one optical pickup is developed. Is being actively conducted. On the other hand, the laser beam for reproducing an optical disk for CD is 780 nm, and the laser beam for reproducing an optical disk for DVD is 650 nm. The material of the semiconductor laser device that emits 780 nm laser light is AlGaAs, and the material of the semiconductor laser device that emits 650 nm laser light is AlGaInP. For this reason, AlG
It is necessary to mount an AlGaAs semiconductor laser device manufactured from an aAs-based material and a semiconductor laser device manufactured from an AlGaInP-based material on an optical pickup. In addition, in order to reduce the cost of the optical pickup, it is required that the light be condensed on an optical disk using one optical lens system. For this reason, it has been necessary to arrange the light emitting layers of the two semiconductor laser devices in proximity to each other within approximately 100 μm.

Generally, a semiconductor laser device is an MOCV
D (Metal Organic Chemical V)
apo Deposition method or MBE (Mocu
lar Beam Epitaxy) method.

A conventional semiconductor laser device will be described below. FIG. 11 is a cross-sectional view showing a conventional semiconductor laser device 30 that emits two wavelengths. Semiconductor laser device 3
0 denotes an AlGaAs semiconductor laser element 31 formed on a GaAs substrate 2, an AlGaInP semiconductor laser element 34, an AlGaAs semiconductor laser element 31,
Formed between the InP semiconductor laser element 34 and G
Separation groove 3 etched partway through aAs substrate 2
And 7. AlGaAs semiconductor laser device 3
1 includes an AlGaAs semiconductor layer 32 including a light emitting layer 33, and an AlGaInP semiconductor laser device 34 includes a light emitting layer 3
The semiconductor device has an AlGaInP semiconductor layer 35 containing the same. Note that the distance between the light emitting layer 33 and the light emitting layer 36 is approximately 100
It is within μm.

An AlGaAs semiconductor laser device 31 and A
The operation of the lGaInP semiconductor laser device 34 is performed by injecting a current equal to or more than the oscillation threshold value into the AlGaAs semiconductor laser device 31 and the AlGaInP semiconductor laser device 34, thereby emitting laser light from the light emitting layers 33 and 36. .

It is to be noted that the semiconductor laser device 30
When reproducing an optical disk for DVD, the current is higher than the oscillation threshold value by injecting the current into the AlGaAs semiconductor laser device 31. When reproducing an optical disk for DVD, the AlGaInP semiconductor laser device 34 has an oscillation threshold. This can be achieved by injecting a current equal to or greater than the value.

[0007]

However, since the isolation trench 37 is filled with air and has poor thermal conductivity, the AlGaAs semiconductor laser device 31 or the AlGa
The heat generated during the operation of the InP semiconductor laser device 34 cannot be efficiently released to the outside. The semiconductor laser device 30 has been degraded due to crystal defects and dislocations generated by the heat, and thus has a problem that reliability is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a semiconductor laser device having a structure capable of efficiently discharging heat generated from a semiconductor laser device. And

[0009]

According to a first aspect of the present invention, there is provided a semiconductor laser device having a first semiconductor laser device and a second semiconductor laser device formed adjacent to each other on a semiconductor substrate. In the semiconductor laser device, a separation groove formed between the first semiconductor laser device and the second semiconductor laser device and formed by etching halfway in the semiconductor substrate, and is sequentially formed in the separation groove. It is characterized by comprising an insulating layer and a metal layer.

According to a second aspect of the present invention, in the semiconductor laser device according to the first aspect, the metal layer is made of Ti or Au.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a semiconductor laser device according to the present invention will be described with reference to FIG. FIG. 1 is a sectional view showing a semiconductor laser device of the present invention.

A semiconductor laser device 1 according to the present invention will be described below with reference to FIG. First, the configuration of the semiconductor laser device 1 of the present invention will be described. The semiconductor laser device 1 includes an AlGaAs semiconductor laser device 3 formed adjacent to an n-type GaAs substrate 2 and an AlGaI semiconductor laser device 3.
a separation groove 5 having an nP semiconductor laser element 4, formed between the AlGaAs semiconductor laser element 3 and the AlGaInP semiconductor laser element 4, and formed by etching halfway through the n-type GaAs substrate; , And an insulating layer 6 and a metal layer 7 formed sequentially. The insulating layer 6 is composed of the AlGaAs semiconductor laser device 3 and the AlGaIn
In order to electrically isolate the P semiconductor laser device 4 from the AlGaAs semiconductor laser device 3, the metal layer 7
It is provided to efficiently release the heat generated from the InP semiconductor laser device 4 to the outside. The insulating layer 6
Is made of a material such as SiO ₂ and Si ₂ N ₃ . The metal layer 7 is made of, for example, a material of Ti or Au.

Further, an AlGaAs semiconductor laser device 3
Has the following configuration. On an n-type AlGaAs cladding layer 8 (Si-doped, 1 μm thick), an AlGaAs active layer 9 (0.13 μm, non-doped) and a first p-type AlGaAs clad layer 10 (Zn-doped, 0.2 μm thick)
μm), p-type AlGaAs etching stop layer 11
(Zn-doped, thickness 0.03 μm) are sequentially laminated. On the p-type AlGaAs etching stop layer 11, a second p-type AlGaAs cladding layer 12 (Zn-doped, 0.8 μm thick), a p-type GaAs cap layer 13
(Zn-doped, 0.3 μm in thickness), and a pair of n-type G layers sandwiching the ridge 14.
aAs current confinement layers 15a, 15a (Si-doped, 0.8 μm thick) are formed.

A p-type GaAs contact layer 16a is formed on the ridge 14 and the pair of n-type GaAs current confinement layers 15a, 15a.
A p-type ohmic electrode 17a is formed on 6a.

Also, the AlGaInP semiconductor laser device 4
Has the following configuration. AlGaI on the n-type AlGaInP cladding layer 19 (Si-doped, 1 μm thick)
nP active layer 20 (non-doped), first p-type AlGaI
nP cladding layer 21 (Zn-doped, thickness 0.2 μm),
A p-type AlGaInP etching stop layer 22 (0.03 μm in thickness) is sequentially laminated. Where AlG
The aInP active layer 20 has three pairs of GaIn between the pair of AlGaInP guide layers 20a and 20a (non-doped).
P quantum well layer 20b and two pairs of AlGaInP barrier layers 2
0c are alternately formed and the GaInP quantum well layer 20 is formed.
b has a configuration adjacent to the AlGaInP guide layer 20a.

On the p-type AlGaInP etching stop layer 22, a second p-type AlGaInP cladding layer 23 is formed.
(Thickness 0.8 μm), a ridge portion 25 in which a p-type GaAs cap layer 24 (thickness 0.3 μm) is sequentially stacked, and a pair of n-type GaAs current confinement layers 15 b, 15 b ( (Thickness: 0.8 μm).
Ridge part 25 and pair of n-type GaAs current confinement layers 15
A p-type GaAs contact layer 16b is formed on the p-type GaAs contact layer 16b.
A type ohmic electrode 17b is formed. The n-type GaAs substrate 2 in the direction opposite to the lamination direction has Al
An n-type ohmic electrode 18 common to the GaAs semiconductor laser device 3 and the AlGaInP semiconductor laser device 4 is formed.

Next, the operation of the semiconductor laser device 1 will be described. When operating the AlGaAs semiconductor laser device 3, a current equal to or higher than the oscillation threshold is injected from the p-type ohmic electrode 17a toward the n-type ohmic electrode 18, and this current is applied to the p-type ohmic electrode 18. Electrode 17a → p-type Ga
As contact layer 16a → ridge 14 → p-type AlGa
As etching stop layer 11 → first p-type AlGaAs
s cladding layer 10 → AlGaAs active layer 9 → n-type AlG
The light flows from the aGaAs cladding layer 8 → the n-type GaAs substrate 2 → the n-type ohmic electrode 18 to the light emitting layer P of the AlGaAs active layer 9.
The laser light is emitted from. The operation of the AlGaInP semiconductor laser device 4 is the same as the operation of the AlGaAs semiconductor laser device 3 only by replacing AlGaAs with AlGaInP. That is, a current higher than the oscillation threshold is injected from the p-type ohmic electrode 17b toward the n-type ohmic electrode 18, and this current is changed from the p-type ohmic electrode 17b to the p-type GaAs contact layer 16b. Ridge 25 → p-type AlGaInP etching stop layer 2
2 → first p-type AlGaInP cladding layer 21 → AlG
aInP active layer 20 → n-type AlGaInP clad layer 1
9 → n-type GaAs substrate 2 → n-type ohmic electrode 18, and laser light is emitted from the light emitting layer Q of the AlGaInP active layer 20. At this time, since the metal layer 7 is formed in the separation groove 5 formed between the AlGaAs semiconductor laser element 3 and the AlGaInP semiconductor laser element 4, heat generated from these semiconductor laser elements is 7 can be efficiently released to the outside.

Further, since the insulating layer 6 is formed in the separation groove 5, the AlGaAs semiconductor laser device 3 and the AlGa
Since the AlGaAs semiconductor laser element 3 is electrically separated from the InP semiconductor laser element 4, the current injected into the AlGaAs semiconductor laser element 3 does not flow through the AlGaInP semiconductor laser element 4 when operating the AlGaAs semiconductor laser element 3. Only the AlGaAs semiconductor laser device 3 can be operated. The same applies to the case where only the AlGaInP semiconductor laser device 4 is operated. AlGaAs
When operating the semiconductor laser device 3 and the AlGaInP semiconductor laser device 4 simultaneously, the p-type ohmic electrode 1
A current equal to or higher than the oscillation threshold may be simultaneously injected from 7a and 17b toward the n-type ohmic electrode 18.

Note that the AlGaAs active layer 9 and the AlGa
The emission from the light-emitting layers P and Q of the light emitted by the InP active layer 20 will be described below. A pair of n-type GaAs current confinement layers 15a and 15a and a pair of n-type Ga
A corresponding to the As current confinement layers 15b, 15b
Since the laser light emitted from the AlGaAs active layer 9 and the AlGaInP active layer 20 is absorbed in the 1GaAs active layer 9 and the AlGaInP active layer 20, the ridge portion 1
AlGaAs active layer 9 and AlGa corresponding to 4 and 25
Laser light is emitted from the InP active layer 20 portion. That is, a portion corresponding to the ridge portion 14 of the AlGaAs active layer 9 becomes the light emitting layer P, and a portion corresponding to the ridge portion 25 of the AlGaInP active layer 20 becomes the light emitting layer Q.

As described above, the semiconductor laser device 1 according to the embodiment of the present invention comprises an AlGaAs semiconductor laser device 3 and an AlGaAs semiconductor laser device.
A separation groove 5 formed between the GaInP semiconductor laser element 4 and etched partway in the n-type GaAs substrate 2; and an insulating layer 6 sequentially formed in the separation groove 5
And the metal layer 7, the AlGaAs semiconductor laser element 3 and the AlGaInP semiconductor laser element 4 are electrically separated from each other, and the AlGaAs semiconductor laser element 3
Heat generated from the GaInP semiconductor laser device 4 can be efficiently released to the outside via the metal layer 7.
For this reason, in the semiconductor laser device 1, the occurrence of crystal defects and dislocations can be reduced, and stable operation can be performed. As a result, the semiconductor laser device 1 has sufficient reliability.

A method of manufacturing the semiconductor laser device 1 according to the embodiment of the present invention will be described below with reference to FIGS. (First Step) As shown in FIG.
On an n-type GaAs substrate 2, an n-type AlGaAs cladding layer 8, an AlGaAs active layer 9, a first p-type AlGaAs cladding layer 10, a p-type AlGaAs etching stop layer 11, a second p-type AlGaAs cladding layer 12, a p-type G
The aAs cap layer 13 is sequentially laminated.

(Second Step) As shown in FIG. 3, an SiO ₂ layer 26 is formed on the p-type GaAs cap layer 13 by sputtering, and a photoresist pattern 27 is formed on the SiO ₂ layer 26 by photolithography. To form
Thereafter, the SiO ₂ layer 26 other than that covered with the photoresist pattern 27 is etched by a dry etching method.

(Third Step) Subsequently, as shown in FIG.
After removing the photoresist pattern 27 using an organic solvent, the n-type GaAs substrate 2 other than the one covered with the SiO ₂ layer 26 is etched using a phosphoric acid-based etchant.

(Fourth Step) Next, as shown in FIG.
The n-type AlGaInP cladding layer 19 and the AlGaP are formed on the n-type GaAs substrate 2 and the SiO ₂ layer 26 by the OCVD method.
InP active layer 20, first p-type AlGaInP cladding layer 21, p-type AlGaInP etching stop layer 2
2, the second p-type AlGaInP cladding layer 23, the p-type G
The aAs cap layer 24 is sequentially laminated. In addition, AlGa
The InP active layer 20 includes a GaInP quantum well layer 20b, an AlGaInP barrier layer 20c, a GaInP quantum well layer 20b, and an AlGaIn
P barrier layer 20c, GaInP quantum well layer 20b, Al
It is formed by sequentially laminating the GaInP guide layers 20a.
At this time, these layers do not grow on the SiO ₂ layer 26,
It grows only on the n-type GaAs substrate 2.

This can be explained as follows. In general, when growing a group III-V compound semiconductor crystal using the MOCVD method, an organic metal gas containing a group III element constituting the semiconductor crystal and a group V element are deposited on the semiconductor substrate while the semiconductor substrate is heated. A hydrogen compound gas containing the compound, and thermally decomposes the organic metal gas into a group 3 element and an organic substance and the hydrogen compound gas into a group 5 element and hydrogen by the catalytic action of the semiconductor substrate;
The thermal decomposition is performed by chemically bonding the thermally decomposed Group 3 element and Group 5 element on the semiconductor substrate. For this reason,
Since the n-type GaAs substrate 2 has a catalytic action to thermally decompose these organometallic gases and hydrogen compounds, the thermally decomposed Group 3 element and Group 5 element are chemically bonded to form the n-type GaAs substrate 2. It is formed. On the other hand, since the SiO ₂ layer 26 does not have the above-described catalytic action, it cannot be formed on the SiO ₂ layer 26 by thermally decomposing an organic metal gas or a hydrogen compound gas. Therefore, each of the above-described layers is made of n-type GaAs.
It grows only on the substrate 2 and does not grow on the SiO ₂ layer 26.

(Fifth Step) Subsequently, as shown in FIG.
After the SiO ₂ layer 26 is removed by etching, SiO ₂ is formed on the p-type GaAs cap layers 13 and 24 by sputtering, and photoresist patterns 29 and 29 are formed on the SiO ₂ by photolithography. At this time, the interval between the photoresist patterns 29, 29 is 10
Keep it within 0 μm. After that, the photoresist pattern 2
SiO ₂ other than those covered with 9 and 29 are removed by etching to form SiO ₂ patterns 28 and 28.

(Sixth Step) Thereafter, using an organic solvent,
The photoresist patterns 29 are removed. Furthermore,
As shown in FIG.
_Second p-type AlGaAs other than covered with _two layers 28, 28
s cladding layer 12, p-type GaAs cap layer 13, second p-type AlGaInP cladding layer 23, p-type GaAs
The cap layer 24 is etched to the p-type AlGaAs etching stop layer 11 and the p-type AlGaInP etching stop layer 22, respectively, to form the ridge portions 14 and 25. At this time, the ridge 14 and the ridge 25 become trapezoidal due to the flow of the etching solution.

(Seventh Step) Next, as shown in FIG.
By the OCVD method, n-type Ga is formed on the ridge portion 14, the ridge portion 25, the p-type AlGaAs etching stop layer 11 and the second p-type AlGaInP etching stop layer 22.
An As current confinement layer 15 is formed. At this time, n-type GaAs
The current confinement layer 15 grows only on the ridge portion 14, the ridge portion 25, the p-type AlGaAs etching stop layer 11 and the second p-type AlGaInP etching stop layer 22, and does not grow on the SiO ₂ patterns 28. This is the same as the reason explained in the above (the fourth step).

As shown in (eighth step) FIG. 9, SiO ₂
After removing the patterns 28 and 28 by etching, the MOCV
The ridge portion 14, the ridge portion 25 and the n-type Ga
A p-type GaAs contact layer 16 is formed on the As current confinement layer 15.
To form Further, a p-type ohmic electrode 17 is formed on the p-type GaAs contact layer 16 by a vacuum deposition method,
An n-type ohmic electrode 18 is formed on the n-type GaAs substrate 2 on the side opposite to the stacking direction.

(Ninth Step) Thereafter, as shown in FIG. 10, an opening (not shown) is formed in the portion corresponding to the portion between the ridge portion 14 and the ridge portion 25 on the p-type ohmic electrode 17 by photolithography. Is formed. Next, the p-type ohmic electrode 17 exposed from this opening is used to dry the n-type G
The isolation groove 5 is formed by etching a part of the aAs substrate 2. Here, the p-type ohmic electrode 17 is connected to the p-type ohmic electrodes 17 a and 17 b by the separation groove 5.
The GaAs contact layer 16 includes an n-type GaAs current confinement layer 15 on the p-type GaAs contact layers 16a and 16b.
Are separated into n-type GaAs current confinement layers 15a and 15b.

(Tenth Step) Further, after a photoresist pattern (not shown) is formed by photolithography, an insulating film made of SiO ₂ , Si ₂ N ₃ or the like is formed in the photoresist pattern (not shown) and the separation groove 5 by sputtering. A layer 6 and a metal layer 7 made of Ti, Au or the like are sequentially formed. Thereafter, the photoresist pattern (not shown) is removed with an organic solvent to obtain the semiconductor laser device 1 shown in FIG. The insulating layer 6 and the metal layer 7 formed on the photoresist pattern (not shown) are removed at the same time as removing the photoresist pattern with an organic solvent.

As described above, since the separation groove 5 is etched using ions by the dry etching method, it can be manufactured with high accuracy regardless of a metal or semiconductor material. For this reason, the metal layer 7 formed in the separation groove 5 can also be formed with high accuracy, so that the heat generated from the semiconductor laser device 1 can be constantly and stably emitted.

The reliability of the semiconductor laser device 1 manufactured as described above was measured by passing a current of 50 mA in an environment at an ambient temperature of 70 ° C.
Had only a 100-hour reliability life,
It has been found that the semiconductor laser device 1 has a reliable life up to 00 hours and has sufficient reliability.

[0034]

According to the semiconductor laser device of the present invention, the semiconductor laser device is formed between the first semiconductor laser device and the second semiconductor laser device formed adjacent to each other on the semiconductor substrate, and A separation groove etched and formed halfway in the semiconductor substrate, and an insulating layer sequentially formed in the separation groove,
The first semiconductor laser element and the second
And the heat generated when operating the first semiconductor laser element and the second semiconductor laser element can be efficiently released to the outside. Therefore, the semiconductor laser device can reduce the occurrence of crystal defects and dislocations, and can obtain good reliability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a semiconductor laser device of the present invention.

FIG. 2 is a cross-sectional view showing a first step of the method for manufacturing a semiconductor laser device of the present invention.

FIG. 3 is a sectional view showing a second step of the method for manufacturing a semiconductor laser device of the present invention.

FIG. 4 is a sectional view showing a third step of the method for manufacturing a semiconductor laser device of the present invention.

FIG. 5 is a sectional view showing a fourth step of the method for manufacturing a semiconductor laser device of the present invention.

FIG. 6 is a sectional view showing a fifth step of the method for manufacturing a semiconductor laser device of the present invention.

FIG. 7 is a sectional view showing a sixth step of the method for manufacturing a semiconductor laser device of the present invention.

FIG. 8 is a cross-sectional view showing a seventh step of the method for manufacturing a semiconductor laser device of the present invention.

FIG. 9 is a cross-sectional view showing an eighth step of the method for manufacturing a semiconductor laser device of the present invention.

FIG. 10 shows a ninth method of manufacturing a semiconductor laser device of the present invention.
It is sectional drawing which shows a process.

FIG. 11 is a sectional view showing a conventional semiconductor laser device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser element, 2 ... n-type GaAs substrate (semiconductor substrate), 3 ... AlGaAs semiconductor laser element (first semiconductor laser element), 4 ... AlGaInP semiconductor laser element (second semiconductor laser element), 5 ... Separation groove, 6 ... Insulating layer, 7 ... Metal layer

Claims (2)

[Claims] 1. A semiconductor laser device having a first semiconductor laser device and a second semiconductor laser device formed adjacent to each other on a semiconductor substrate, wherein the first semiconductor laser device and the second semiconductor laser device A semiconductor laser, comprising: a separation groove formed between a semiconductor laser element and etched partway through the semiconductor substrate; an insulating layer sequentially formed in the separation groove; and a metal layer. element. 2. The semiconductor laser device according to claim 1, wherein said metal layer is made of Ti or Au.