JPH10335741A - Semiconductor laser element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser element in high mass productivity capable of assembling without causing any defective crystal or transposition in the light emitting region of the semiconductor element. SOLUTION: In a semiconductor laser element 1, a first clad layer 3, an active layer 4, a second clad layer 5, a current strangulated layer 6, a contact layer 7 are successively laminated at least on one surface of a semiconductor substrate 2 while an ohmic electrode 11 is formed on the other surface, a light emitting region B and an electric connection region C are separated by a separating part 8 formed at least in such a manner as separating the first clad layer 3 from the contact layer 7, while a laser outgoing part A is provided in a light emitting region.

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 having an effective structure for improving reliability during assembly and a method of manufacturing the same.

[0002]

2. Description of the Related Art Semiconductor laser elements are widely used as light sources for consumer equipment such as optical pickups and laser printers, and are required to have high reliability. When assembling the semiconductor laser device, it is important to prevent crystal defects and dislocations that cause a reduction in reliability from being generated in the semiconductor laser device, particularly in the active layer. Various forms of a semiconductor laser element and an assembling method for this purpose are considered.

FIG. 9 is a sectional view of a conventional semiconductor laser device. The semiconductor laser device 100 includes an n-GaAs substrate 101, an n-GaAlAs cladding layer 102, a non-doped GaAs active layer 103, and a p-GaAlAs cladding layer 104, which are sequentially stacked. Then, a p-ohmic electrode 105 is formed. The n-GaAs substrate 101 on the opposite side of the lamination direction
Has a structure in which an n-ohmic electrode 106 is formed.

The assembly of the semiconductor laser device 100 on the submount substrate 108 is performed as follows. FIG. 10 is a cross-sectional view showing a first assembly method of the semiconductor laser device 100. The same components as those in FIG. 9 are denoted by the same reference numerals, and detailed description thereof will be omitted.
First, the n-ohmic electrode 106 side is connected to the submount substrate 1.
The semiconductor laser element 100 is adhered to the submount substrate 108 via the brazing material 107 so as to face the semiconductor laser element 100.
On the p-ohmic electrode 105, one end of the Au wire 109 is ultrasonically bonded to the wire, and the other end is ultrasonically bonded to an external device (not shown) to perform electrical connection. Ultrasonic wire bonding is performed by bringing an Au wire 109 into contact with the p-ohmic electrode 105 and then applying Au.
Since this is performed while ultrasonically oscillating the wire 109 at the same time as the wire 109 is pressed, the Au wire 10 on the p-ohmic electrode 105 is
9 has a shape that is crushed and spread laterally.
Generally, as a wire bonding method, ultrasonic wire bonding can be easily performed by simply pressing the semiconductor laser element 100 and generating ultrasonic vibration.
It is widely and commonly used because mass production effects can be expected.

However, in such an ultrasonic wire bonding to the semiconductor laser element 100, the non-doped GaAs active layer 103 is formed at a position within several tens μm from the p-type ohmic electrode 105. The load and impact during ultrasonic wire bonding are directly
In addition to the aAs active layer 103, it causes crystal defects and dislocations. For this reason, the semiconductor laser element 100 causes an increase in threshold current and thermal deterioration, which significantly impairs the reliability. In view of this, an assembly method has been devised in which the semiconductor laser element 100 is turned upside down to reduce the load and impact during ultrasonic wire bonding.

FIG. 11 shows a second example of the semiconductor laser device 100.
10 is a cross-sectional view showing an assembly method of FIG.
The same reference numerals are given to the same components as those described in the above, and the detailed description thereof will be omitted. FIG. 11 shows the semiconductor laser device 100 of FIG.
The semiconductor laser device 100 is bonded to the submount substrate 108 via a brazing material 107 with the 05 side facing downward on the submount substrate 108 side. In this case, since ultrasonic wire bonding is performed on the n-ohmic electrode 106 side, the distance between the non-doped GaAs active layer 103 and the wire bonding position becomes longer, so that the ultrasonic wire bonding is performed. Non-doped GaAs
The impact on the active layer 103 is reduced. However, the semiconductor laser element 100 is bonded to the submount substrate 108 by an alloying reaction between the p-ohmic electrode 105 and the brazing material 107 and the submount substrate 108.
Due to the difference in the thermal expansion coefficient between the ohmic electrode 105, the brazing material 107 and the submount substrate 108, thermal strain and stress are generated in the p-ohmic electrode 105, and the influence is exerted on the non-doped GaAs active layer 103. And non-doped Ga
This causes crystal defects and dislocations to occur in the As active layer 103. As described above, even when the ultrasonic wire bonding is performed on the n-ohmic electrode 106 side, the first
Semiconductor laser device 100 as in the assembly method of FIG.
In this case, the threshold current increases and thermal degradation occurs, and reliability is impaired. Therefore, the impact of the ultrasonic wire bonding is further reduced, and the p-ohmic electrode 105,
In order to reduce the effect of the alloying reaction with the brazing material 107 and the submount substrate 108, the semiconductor laser element 100 is placed on the submount substrate 108 and the A soft bonding assembly method has been devised which does not use an ultrasonic wave so that a shock at the time of wire bonding is not applied.

FIG. 12 is a sectional view showing a third method of assembling the semiconductor laser device 100, and FIGS.
The same reference numerals are given to the same components as those described in the above, and the description is omitted. FIG. 12 is a view similar to FIG.
Instead of wire bonding on the p-ohmic electrode 105, a solder material 110 is placed at a predetermined position on the p-ohmic electrode 105, and the Au wire 109 is attached to the solder material 110.
After that, the solder material 110 is heated and fused, then cured and wire-bonded. In this case, since the wire bonding becomes the soft bonding, the impact on the non-doped GaAs active layer 103 is reduced. Further, the semiconductor laser element 100 is bonded to the submount substrate 108 with the n-ohmic electrode 106 side down, and the non-doped GaAs active layer 103 is bonded.
And the submount substrate 108, the influence of thermal strain and stress exerted upon alloying with the brazing material 107 is less likely to propagate to the non-doped GaAs active layer 103. For this reason, non-drain due to thermal strain, stress, etc.
No crystal defects or dislocations are generated in the GaAs active layer 103, and a highly reliable semiconductor laser device 100 can be obtained.

[0008]

However, the size of the semiconductor laser element 100 is very small, about several hundreds of micrometers, and the solder material 110 is easy to spread. It is difficult to form the solder material 110 at a predetermined position on the p-ohmic electrode 105 with high accuracy, so that accurate soft bonding cannot be performed. Further, after the Au wire 109 is brought into contact with the solder material 110, a step of heating and fusing and then curing is required, so that the productivity is reduced. Therefore, the present invention
It was made to solve the above problems,
An object of the present invention is to provide a semiconductor laser device having a structure capable of performing assembly with high mass productivity without generating crystal defects or dislocations in a light emitting region of the semiconductor laser device.

[0009]

SUMMARY OF THE INVENTION A semiconductor laser according to the present invention is provided.
According to a first aspect of the present invention, as a first invention, at least a first clad layer, an active layer, a second clad layer,
A current confinement layer and a contact layer are sequentially laminated, and n
A semiconductor laser device having an ohmic electrode formed thereon,
The semiconductor laser device is separated into a light emitting region and an electric connection region by a separating portion formed so as to separate at least the first cladding layer from the contact layer, and a laser emitting portion is provided in the light emitting region. Is provided.

According to a second aspect of the present invention, in the semiconductor laser device according to the first aspect, the separation portion is a groove formed by etching at least halfway through the first cladding layer. .

According to the method for manufacturing a semiconductor laser device of the present invention, a light emitting region for emitting laser light is provided on a semiconductor substrate;
A first step of separately forming an electric connection region electrically connected to the light emitting region; and forming a metal layer for electrically connecting the light emitting region and the electric connection region on the light emitting region. A second step of integrally forming on the semiconductor substrate between the light emitting region and the electric connection region on the electric connection region.

According to the semiconductor laser device and the method of manufacturing the same of the present invention, the following operations are provided. The light emitting region provided with the laser light emitting portion and the electric connection region for making an electrical connection to the light emitting region are separated by a separating portion, and the light emitting region is connected to the light emitting region when bonding to the electric connection region. Is reduced, the occurrence of crystal defects and dislocations in the laser light emitting portion is greatly reduced, and a highly reliable semiconductor laser device can be obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a semiconductor laser device according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a semiconductor laser device 1 according to the present invention. FIG. 2 is a sectional view showing a method of assembling the semiconductor laser device 1 according to the present invention.

The semiconductor laser device 1 of the present invention has the following structure. 0.8 μm thick on n-GaAs substrate 2
N-GaAlAs cladding layer 3, non-doped GaAs active layer 4 having a thickness of 0.06 μm, p-G having a thickness of 0.8 μm
aAlAs clad layer 5, n-type GaAs 0.8 μm thick
An s current confinement layer 6 is sequentially stacked, and a groove 6 a is formed in a part of the n-GaAs GaAs current confinement layer 6 by etching up to the p-GaAlAs cladding layer 5. Therefore, n
One GaAs current confinement layer 6 has two regions 6 with a groove 6a interposed therebetween.
_1, 6 ₂ are formed. Furthermore, to form these n one GaAs current confinement layer region 6 _1, 6 ₂ and p-GaAlAs cladding layer 5 thickness 1μm is formed on p-GaAlAs contact layer 7. The p-GaAlAs contact layer 7, n one GaAs current confinement layer region 6 _1, 6 ₂ of the recess 7a on the groove 6a so are stacked along the shape is formed.

Further, the p-GaAlAs contact layer 7 is divided into approximately two parts.
To the middle of the n-GaAs substrate 2 to form a groove 8 by etching. Therefore, the p-GaAlAs contact layer 7 two regions 7 to _1, 7 ₂ is formed. Here, the light emitted from the non-doped GaAs active layer 4 will be considered. The light emitted from the non-doped GaAs active layer 4 spreads in the stacking direction or the direction opposite to the stacking direction.
-GaAs current blocking layer regions 6 _1, the refractive index of the 6 ₂ p-Ga
Since it is designed higher than the AlAs cladding layer 5,
The n-GaAs current confinement layer 6 functions as an absorption layer, in which light emitted from the non-doped GaAs active layer 4 is absorbed. As a result, through the p-GaAlAs cladding layer 5, n-GaAs current confining layer region 6 _1, the 6 ₂ p-GaAlAs contact layer 7 sandwiched between the lower throat - in the light-area A of the flop GaAs active layer 4 Only light is ray
Contributes to the oscillation. Therefore, the region A of the non-doped GaAs active layer 4 becomes a laser emitting portion. Thus, the groove 8
Is separated into a light emitting region B having a laser emitting portion A for emitting laser light, and an electric connecting region C which does not contribute to light emission but can be used for making electrical connection by wire bonding or the like. .

Furthermore, p-GaAlAs contact layer ₇₁ of a portion of the light emitting region B, and the groove 8 so as to cover all of the electrical connection regions 7 ₂ to form an insulating layer 9. Next, p-Ga
A p-ohmic electrode 10 is formed on the AlAs contact layer 7 and the insulating layer 9. Also, n- on the opposite side to the laminating direction
An n-ohmic electrode 11 is formed on the GaAs substrate 2.

[0017] p o - when current is injected from the ohmic electrodes 10, current, p o - ohmic electrode 10, n-GaAs current confining layer region 6 _1, 6 ₂ p-GaAlAs contact layer 7 sandwiched between, p-GaAlAs clad layer 5, non-doped
GaAs active layer 4, n-GaAlAs clad layer 3,
After flowing through the n-GaAs substrate 2 and the n-ohmic electrode 11 and exceeding the oscillation threshold, the non-doped GaAs active layer 4
The laser light is emitted from the laser emission part A of FIG.

The assembly of the semiconductor laser device 1 on the submount substrate 13 is performed as follows. FIG.
As shown in FIG. 5, the semiconductor laser element 1 is bonded to the sub-mount substrate 13 via a brazing material 12 such as In or Ag paste with the n-ohmic electrode 11 side facing the sub-mount substrate 13. I do. Next, one end of the Au wire 14 is ultrasonically bonded to the p-ohmic electrode 10 in the electric connection region C, and the other end is ultrasonically bonded to an external connection device (not shown). The electrical connection with the element 1 is made.

Here, the light emitting region B and the electric connection region C are
Since the Au wire 14 is separated by the groove 8, when the Au wire 14 is bonded to the p-ohmic electrode 10 in the electric connection region C by ultrasonic wire bonding, the propagation of the shock to the light emitting region B is reduced. Therefore, the occurrence of crystal defects and dislocations in the light emitting region B, especially in the non-doped GaAs active layer 4, is eliminated. Further, the semiconductor laser element 1 is connected to the n-ohmic electrode 11.
Since the non-doped GaAs active layer 4 and the sub-mount substrate 13 are adhered to each other via the brazing material 12 with the side facing down, the distance between the non-doped GaAs active layer 4 and the sub-mount substrate 13 is increased. Brazing material 12 and submount substrate 13
The effect of thermal strain and stress during alloying with non-doped Ga
Propagation to the As active layer 4 becomes difficult, and non-doped GaAs
Crystal defects and dislocations generated in the active layer 4 can be prevented. As a result, the semiconductor laser device 1 has high reliability because there is no increase in threshold current and no thermal deterioration. The groove 8
It is sufficient that the groove 8 is at least separated from the light-emitting region B so that the shock at the time of ultrasonic bonding in the electric connection region C does not propagate to the non-doped GaAs active layer 4. , N-GaAlAs cladding layer 3.

Next, a method of manufacturing the semiconductor laser device 1 according to the embodiment of the present invention will be described. 3 to 8 are views showing the steps of manufacturing the semiconductor laser device 1 of the present invention.

(First Step) MOCVD (Me not shown)
tal Organic Chemical Vapo
an n-GaAlAs cladding layer 3 having a thickness of 0.8 μm, a non-doped GaAs active layer 4 having a thickness of 0.06 μm on an n-GaAs substrate 2 by an r Deposition method,
A 0.8 μm thick p-GaAlAs cladding layer 5 and a 0.8 μm thick n-GaAs current confinement layer 6 are sequentially stacked (FIG. 3).

(Second Step) Next, a photoresist (not shown) is applied on the n-GaAs current confinement layer 6, a photoresist pattern is formed by a photolithography method, and then sulfuric acid: hydrogen peroxide solution: water = Using a 3: 1: 1 sulfuric acid mixture, the n-GaAs current confinement layer 6 is formed of p-GaAlA.
Etch to the s-cladding layer 5 and sandwich the groove 6a
One of the n one GaAs current confinement layer region 6 _1, to form a 6 _2.
Thereafter, the photoresist pattern (not shown) is removed using an organic solvent (FIG. 4).

(Third Step) Next, MOCVD (not shown)
The second round of growth by law, laminating the p-GaAlAs contact layer 7 having a thickness of 1μm on the n one GaAs current confinement layer region 6 _1, 6 _2. p-GaAlAs contact layer 7 has a shape having a recess 7a on the groove 6a so are stacked along the shape of the current confinement layer region 6 _1, 6 ₂ (Fig. 5). Here, interposed through the p-GaAlAs cladding layer 5 in n-GaAs current confining layer region 6 _1, 6 ₂ p-
Non-doped GaAs below the GaAlAs contact layer 7
The active layer 4 becomes the laser emission part A.

(Fourth Step) Next, the p-GaAlAs
A photoresist (not shown) is applied on the contact layer 7 to form a photoresist pattern, and phosphoric acid: hydrogen peroxide: water = 8: 1: 1 until the middle of the n-GaAs substrate 2.
The groove 8 is formed by etching using a phosphoric acid mixed solution consisting of Therefore, the p-GaAlAs contact layer 7 two regions 7 to _1, 7 ₂ is formed. After this,
The photoresist pattern (not shown) is removed using an organic solvent (FIG. 6). Thus, the light emitting region B having the separated laser emitting portion A and the electric connection region C which can be used for performing wire bonding or the like are formed by the grooves 8. The phosphoric acid mixed solution has almost the same etching rate for GaAs and GaAlAs, is fast, and has p-G
aAlAs contact layer 7, current confinement layer 6, p-GaAs
1As second cladding layer 5, non-doped GaAs active layer 4
And the total thickness of the n-GaAlAs first cladding layer 3 is 4
Since it is as thin as about μm, the groove 8 can be formed by etching in a short time. Therefore, the amount of side etching in the same plane as the etching surface of each layer is very small, and the groove 8 can be formed as designed.

(Fifth Step) Further, the p-GaAlAs
An insulating layer 9 made of Al ₂ O ₃ is formed by a sputtering method (not shown) so as to cover the contact layer 7 and the entire groove 8. Next, a photoresist (not shown) is applied on the insulating layer 9 to form a photoresist pattern, and only the periphery of the concave portion 7a of the p-GaAlAs contact layer 7 on the light emitting region B is etched away. Thereafter, the photoresist pattern (not shown) is removed using an organic solvent (FIG. 7).

(Sixth Step) Thereafter, an Au p-type ohmic electrode 10 is formed on the p-GaAlAs contact layer 7 and the insulating layer 9 by a sputtering method (not shown) (FIG. 8). Further, an Au-based n-ohmic electrode 11 is formed on the n-GaAs substrate 2 on the side opposite to the lamination direction to obtain the semiconductor laser device 1 shown in FIG.

As described above, since the etching rate of the phosphoric acid mixed solution for GaAs and GaAlAs is almost equal and fast, the amount of side etching in the same plane as the etching surface can be small, and a stable shape can be obtained. A groove 8 is obtained. In addition, the groove 8 emits laser light.
A light emitting region B having the light emitting portion A and an electric connection region C which does not contribute to light emission but can be used for performing electric connection by performing wire bonding or the like can be formed. As a result, the impact of the ultrasonic wire bonding when the ultrasonic wire bonding is performed on the electric connection region C does not propagate to the light emitting region B, so that crystal defects and dislocations in the non-doped GaAs active layer 4 are not generated. Thus, a highly reliable semiconductor laser device 1 can be obtained.

[0028]

According to the semiconductor laser device and the method of manufacturing the same of the present invention, the light emitting region provided with the laser light emitting portion and the electric connection region having the same laminated structure as the light emitting region are separated by the separating portion. The active layer is separated and the physical impact on the light emitting region during bonding to the electrical connection region is reduced, so that the occurrence of crystal defects and dislocations in the active layer is greatly reduced, and a highly reliable semiconductor laser is obtained. -The element is obtained. Also,
Since the grooves are formed by using a phosphoric acid mixture having the same etching rate for the first cladding layer, the active layer and the second cladding layer, and a high-speed mixture of phosphoric acid, the amount of side etching in the same plane as the etching surface is reduced. Since it can be made very small, a groove having a stable shape can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view showing a structure in which a semiconductor laser element according to the present invention is bonded to a submount substrate and wire bonding is performed.

FIG. 3 is a view showing a first step of a manufacturing process of a semiconductor laser device according to the present invention.

FIG. 4 is a view showing a second step of the manufacturing process of the semiconductor laser device according to the present invention.

FIG. 5 is a view showing a third step in the process of manufacturing the semiconductor laser device according to the present invention.

FIG. 6 is a view showing a fourth step in the process of manufacturing a semiconductor laser device according to the present invention.

FIG. 7 is a view showing a fifth step in the process of manufacturing a semiconductor laser device according to the present invention.

FIG. 8 is a view showing a sixth step in the process of manufacturing the semiconductor laser device according to the present invention.

FIG. 9 is a sectional view showing a conventional semiconductor laser device.

FIG. 10 is a sectional view showing a first method of assembling a semiconductor laser device in the related art.

FIG. 11 is a sectional view showing a second method for assembling a semiconductor laser device in the related art.

FIG. 12 is a sectional view showing a third conventional method for assembling a semiconductor laser device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser element, 2 ... n-GaAs substrate, 3 ... n
-GaAlAs cladding layer, 4 ... non-doped GaAs active layer, 5 ... p-GaAlAs cladding layer, 6 ... n-Ga
As current confinement layer, 7 ... p-GaAlAs contact layer,
8 ... groove, 9 ... insulating layer, 10 ... p-ohmic electrode, 11 ...
n-ohmic electrode, 12: brazing material, 13: mounting substrate, 14: Au wire, A: laser emitting portion, B: light emitting region, C: electric connection region

Claims (3)

[Claims] 1. A semiconductor in which a first cladding layer, an active layer, a second cladding layer, a current confinement layer, and a contact layer are sequentially laminated on at least one surface of a semiconductor substrate, and an n-ohmic electrode is formed on the other surface. The semiconductor laser element is separated into a light emitting region and an electric connection region by a separation portion formed so as to separate at least the first cladding layer from the contact layer. A semiconductor laser device, wherein a laser emitting portion is provided in a region. 2. The semiconductor laser device according to claim 1, wherein said separation portion is a groove formed by etching at least halfway through said first cladding layer. 3. A first step of separately forming, on a semiconductor substrate, a light emitting region for emitting laser light and an electrical connection region electrically connected to the light emitting region; Forming a metal layer for electrically connecting a connection region to the light emitting region, the electric connection region, and the semiconductor substrate between the light emitting region and the electric connection region; And a method of manufacturing a semiconductor laser device.