JPH10125994A - Semiconductor laser device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor laser device which is lessened in cost by simplifying its manufacturing process. SOLUTION: A resist film 23 is applied onto a wafer 21 and patterned, arranged grooves 24 are provided to the wafer 21, the resist film 23 is removed, an electrode 25 is provided to both the surfaces of the wafer 21, cleaving marks 26 are provided to the wafer 21, and the wafer 21 is cleaved into semiconductor laser bars 27. Furthermore, the semiconductor laser bars 27 are nearly vertically placed on an edge face coating jig 48 so as to make their one cleaved edge faces 28 expose, a protective film 29 is formed on the cleaved edge faces 28, the semiconductor laser bars 27 are nearly vertically placed on an edge face coating jig 48 so as to make their other cleaved edge faces 28 expose, and a protective film 30 is formed on the other cleaved edge faces 28, respectively. The semiconductor laser bars 27 are divided into separate semiconductor laser devices 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor laser device and a method for manufacturing the same.

[0002]

2. Description of the Related Art Such a semiconductor laser device generally comprises a semiconductor substrate 31 and a semiconductor substrate 3 as shown in FIG.
Active layer 32 formed on one first surface along one direction
And a cladding layer 33 sandwiching the active layer 32. Since the structure related to light emission of the semiconductor laser device has already been shown in Japanese Patent Publication No. 6-58988, detailed description of the composition and structure will be omitted here.

Further, a light-emitting surface 34 and a light-emitting back surface 36 are formed on both ends of the active layer 32 of the semiconductor substrate 31, respectively.
The other two faces other than 6, namely the first and second faces,
Electrode surfaces 40 and 38 are formed respectively. And
On the light-emitting surface 34 and the light-emitting back surface 36, a laser light transmitting and reflecting protective film (hereinafter, referred to as a protective film including both) is formed on the light emitting surface 34 and the light emitting rear surface 36, respectively, in order to improve the reliability of the semiconductor laser device and extend the life. Is done.

Hereinafter, such a protective film is formed on the light emitting surface 34 described above.
A conventional method of forming the light emitting back surface 36 will be described.

First, a conventional general protective film forming method will be described with reference to FIG.

In this method of forming a protective film, a plurality of semiconductor laser bars 50 in which semiconductor laser elements formed by cleavage from a semiconductor wafer are arranged in a line are used to cure an end face coating so that one of the light emitting surface 34 and the light emitting back surface 36 is exposed. Tool 5
4 is mounted vertically on the mounting surface 56, and a protective film is formed on the light emitting surface 34 or the light emitting rear surface 36 by sputtering, CVD, or the like.

According to this method, each semiconductor laser bar 5
If even a slight gap is formed between the zeros, spatter,
At the time of CVD or the like, the protective film forming material goes around from the gap and adheres to the electrode surfaces 38 and 40 of the semiconductor laser device.
As a result, when the semiconductor laser bar 50 is separated into chips of the semiconductor laser element in a later step, problems such as peeling of the protective film and generation of cracks may occur. Further, a film is formed on the electrode surfaces 38 and 40 by the protective film forming material, which makes it difficult to mount on the heat sink or wire bonding to the electrode surfaces 38 and 40 cannot be performed, resulting in poor conduction and defective peeling. There is a problem of incentive.

As a method for solving such a problem, FIG.
As shown in (2), a plurality of semiconductor laser bars 50 are aligned so that the electrode surfaces 38 or 40 of the semiconductor laser element are parallel to each other, and a spacer 44 having a length substantially equal to the length of the active layer 32 of each semiconductor laser element is interposed therebetween. There is also adopted a method of inserting the jig into an end face coating jig (not shown) and pressing the jig with a predetermined load from the electrode surface 38 or 40 direction.

According to this method, the spacer 44 covers the electrode surface 38 or 40 of each semiconductor laser element in the semiconductor laser bar 50, and the protective film forming material is applied to the electrode surface 38 or 40 of the semiconductor laser element during sputtering or the like. It is possible to prevent sneak and adhesion.

On the other hand, a method of making the above-mentioned spacer unnecessary is proposed in, for example, JP-A-63-153876. In the method for treating an end face of a semiconductor laser described in Japanese Patent Application Laid-Open No. 63-153876, a gap is formed between the semiconductor laser bars by mounting the semiconductor laser bar at an angle to the mounting surface of the jig. However, it is intended to prevent the formation of a coating film on the electrode surface by making it difficult for the protective film forming substance to enter therethrough.

Further, Japanese Patent Application Laid-Open No. 7-30196 discloses a simple and high-yield protective film without depending on the shape of an end face, and a wafer state without subdivision into a laser bar state. A method is described in which a groove is formed by etching with a method and a protective film is formed on an end face. This method of forming a protective film is a semiconductor device comprising a channel waveguide such as a semiconductor laser, wherein a groove serving as a resonator or an end face of the channel waveguide is formed on a semiconductor substrate, and the semiconductor laser is further provided on a side wall of the groove. After forming a protective film such as the above, an epitaxial layer having a channel waveguide structure is formed in the groove, and a portion other than the channel waveguide is etched to form a light emitting surface and a light emitting back surface of a semiconductor laser or the like. is there.

[0012]

However, in the conventional method shown in FIG. 6, the spacer 44 is sandwiched when the plurality of semiconductor laser bars 50 are aligned, so that the cost is increased by the necessity of the spacer 44. . Further, in order to accurately align and align the end faces of the respective semiconductor laser bars 50 and the spacers 44, a precise end face coating jig provided with a more complicated mechanism than the end face coating jig 54 shown in FIG. There was a problem that tools were required.

On the other hand, in the method described in Japanese Patent Application Laid-Open No. 63-153876, each semiconductor laser bar is mounted so as to be inclined with respect to the mounting surface of the jig. It was difficult to form a protective film having a thickness. Also, when the width of the semiconductor laser bar varies, the surface on which the protective film is to be provided may not always be arranged in a stepwise manner. As a result, for example, when a narrow semiconductor laser bar overlaps with a lower semiconductor laser bar, the latter may be shaded by the former in the sputtering direction, and the protective film may be thin or the protective film may not be formed.

Further, in the method described in JP-A-7-30196, since the light emitting surface and the light emitting back surface are formed by etching, the light emitting surface has irregularities and is not as sharp as the surface formed by cleavage. And the light emission efficiency is poor. Further, in order to obtain the same light emission amount as that of the related art, a large amount of current must be flown, so that the energy loss inside the semiconductor laser device increases. For this reason, the amount of heat generated also increases, which causes a reduction in the life of the semiconductor laser element.

An object of the present invention is to provide a low-cost semiconductor laser device and a manufacturing method thereof by simplifying a manufacturing process of the semiconductor laser device.

It is another object of the present invention to provide a method of manufacturing a semiconductor laser device capable of forming a protective film having a uniform thickness on a light emitting surface or the like of the semiconductor laser device.

Still another object of the present invention is to provide a method of manufacturing a semiconductor laser device capable of simplifying a manufacturing process while maintaining excellent luminous efficiency of a cleavage plane.

[0018]

According to the present invention, there is provided a semiconductor substrate having first and second surfaces facing each other, and an active substrate formed along one direction on the first surface of the semiconductor substrate. A semiconductor light emitting device comprising: a semiconductor substrate; a light emitting surface and a light emitting back surface formed on both ends of the active layer of the semiconductor substrate; and electrode surfaces formed on the first and second surfaces, respectively. A semiconductor laser device is provided in which a notch is provided at a boundary between at least one of the light emitting surface or the light emitting back surface of the substrate and the second surface.

According to the invention, there is provided a semiconductor laser device characterized in that the depth of the notch is not less than 5 μm and not more than the thickness of the semiconductor substrate.

Further, according to the present invention, a step of forming an optical resonator on a first surface of a wafer, and forming a plurality of arrangement grooves orthogonal to the optical resonator on a second surface of the wafer. Forming electrodes on both surfaces of the wafer, cleaving along the center line in the width direction of the arrangement grooves to form a plurality of semiconductor laser bars, and exposing cleavage end faces of the plurality of semiconductor laser bars. And a step of forming a protective film on the cleaved end face, thereby providing a method of manufacturing a semiconductor laser device.

According to the present invention, there is provided a method for manufacturing a semiconductor laser device, wherein the protective film is formed by a sputtering method, and the cleavage end faces are aligned in a direction substantially perpendicular to a sputtering direction. .

According to the invention, there is provided a method of manufacturing a semiconductor laser device, wherein the arrangement groove is formed by etching the semiconductor substrate.

Further, according to the present invention, there is provided a method of manufacturing a semiconductor laser device, wherein the etching is performed by either wet etching with an acidic solution or dry etching with a halogen-based gas.

[0024]

Embodiments of the present invention will be described with reference to the drawings.

As shown in FIGS. 1A, 1B and 1C, a semiconductor laser device 1 according to a first embodiment of the present invention has a semiconductor substrate 2 and a first semiconductor substrate 2. A lower cladding layer 3 and an upper cladding layer 5 formed on the surface, and sandwiched between the lower cladding layer 3 and the upper cladding layer 5;
An active layer (also referred to as an optical resonator) 4 is formed on the first surface of the semiconductor substrate 2 along one direction, and a contact layer 7 is formed on the upper clad layer 5. Semiconductor substrate 2
A light-emitting surface 6 and a light-emitting back surface 8 are formed on both ends of the active layer 4, respectively, and protective films 29 and 30 are coated on the respective surfaces. Electrode surfaces 12 and 10 are formed on two opposing surfaces of the semiconductor substrate 2 other than the light emitting surface 6 and the light emitting back surface 8, that is, the first and second surfaces.
As described in the section of the prior art, the structure related to the light emission of the semiconductor laser device is described in Japanese Patent Publication No. 6-5898.
As already described in No. 8, etc., a detailed description of the composition and structure is omitted here.

The semiconductor laser device 1 according to the present embodiment is characterized in that each of the light emitting surface 6 and the light emitting back surface 8 of the semiconductor substrate 2 and the electrode surface 10 formed on the second surface of the semiconductor substrate 2.
Notches 14 and 14 are provided at the boundary with. If the protective film is formed on only one of the light emitting surface 6 and the light emitting back surface 8, the notch 14 may be provided on only one of them.

FIG. 2 is a diagram schematically showing a manufacturing process of the semiconductor laser device according to the first embodiment shown in FIG.
The method of forming the active layer 4, the lower cladding layer 3, and the upper cladding layer 5 is the same as the conventional method, so that the illustration and description are omitted. FIG. 2A shows a state in which a layer required for a semiconductor laser has already been formed on the surface of the wafer 21.

In order to manufacture the semiconductor laser device of this embodiment, first, as shown in FIG. 2A, resist patterning is performed on the back surface of the wafer 21. That is, the wafer 21
After a resist film 23 is applied on the back surface of the wafer 21 having the active layer 4 formed on the surface thereof, patterning is performed by photolithography to form a mask pattern.
In this embodiment, the thickness of the wafer 21 is about 100 μm.
m. An organic protective film was used as the type of the resist.

Next, as shown in FIG. 2B, the wafer 21 is wet-etched at room temperature for 2 to 3 minutes using an acid-based etchant such as sulfuric acid using the resist film 23 as an etching mask. A plurality of arrangement grooves 24 are formed on the back surface. Here, the arrangement groove 24 is formed in a direction orthogonal to the active layer 4.

Subsequently, as shown in FIG. 2C, the resist is removed using an organic solvent. Thereby, as shown in the figure, a flat portion 46 having a width of about 500 μm and a flat portion 46 having a width of about 40 μm are formed.
An array groove 24 having a depth of about 20 μm is formed.

Further, as shown in FIG.
The electrodes 25 are formed on both the front and back surfaces of No. 1. In this embodiment,
A Cr-Au electrode for the p-side ohmic electrode,
AuGe-Au electrodes for the n-side ohmic electrode were each formed by a vacuum deposition method. In order to make ohmic contact between the p-type and n-type electrodes, 200 to 3
Heat treatment was performed at 00 ° C. for 20 to 30 minutes.

Next, as shown in FIG. 2E, a diamond pointer is used to cleave to a depth of several μm on the front side of the wafer 21 so as to correspond to the center in the width direction of the arrayed grooves 24 on the back side. 2 (f), the wafer 21 is cleaved, and a plurality of semiconductor laser bars 2 are formed.
7 is formed. As a result, as shown in FIG.
Cleaved end faces 2 are provided on both sides of each semiconductor laser bar 27 in the width direction.
8 are formed respectively.

Subsequently, as shown in FIG. 2 (g), the plurality of semiconductor laser bars 27 are aligned substantially perpendicular to the mounting surface 48a of the end face coating jig 48, and Hold and fix by applying force from the left and right,
As shown in FIGS. 2H and 2I, the cleavage end face 28
Protective films 29 and 30 are respectively formed on both surfaces of.

That is, first, as shown in FIG. 2H, a protective film 29 as a highly reflective film is formed on one cleavage end face 28 to a thickness of 300 to 500 nm by a sputtering method. As shown in FIG. 2 (i), a protective film 30 as an anti-reflection film is formed on the other cleavage end face 28 to a thickness of about 100 nm similarly by the sputtering method. Here, the cleavage end face 28 is in the direction in which particles fly from the sputtering source (hereinafter, referred to as
(Referred to as the sputter direction).
A uniform film thickness can be obtained regardless of the arrangement position of the semiconductor laser bars. The sputtering conditions were as follows:
Under 0-20 mTorr, high frequency power of 1-3 kW output was used. The material of the film is SiO ₂ or Al ₂ O
No. ₃ single layers, or these were alternately laminated.

As a result, as shown in FIG. 2J, each semiconductor laser bar 27 on which the protective films 29 and 30 are formed is obtained. Subsequently, the semiconductor laser bar 27 is pelletized with a size of 300 μm.
As shown in (k), each semiconductor laser bar 27 is separated into individual chip-shaped semiconductor laser elements (pellets) 1.

The semiconductor laser device 1 according to the first embodiment manufactured by the above method has a rectangular shape of 540 × 300 μm shown in FIG. 1A, and as shown in FIG. A width of about 20 μm and a depth of about 20 μm formed by splitting the array groove 24 into two on the back surface.
m are formed at both ends in the width direction. These steps make each of the light emitting surface 6 and the light emitting back surface 8 and one of the electrode surfaces 10.
Cutouts 14 and 14 are formed at the boundary with.
The semiconductor laser element (pellet) 1 includes a flat portion 46 having a width of about 500 μm as shown in FIG. It has been confirmed that the same effect can be obtained if the depth of the array groove 24 is 5 μm or more. In addition, when the arrangement groove 24 reaches the lower cladding layer 3, the light emitting surface becomes uneven, and the luminous efficiency decreases. Therefore, the depth of the arrangement groove 24 needs to be smaller than the thickness of the semiconductor substrate 2.

As can be seen from FIGS. 1 (a) and 1 (c), in the protective film forming step shown in FIGS. 2 (h) and 2 (i), the material for forming the protective film is a semiconductor laser device (pellet).
However, the adhesion stays in the cutouts 14 and 14 and does not reach the flat portion 46. Therefore, when the semiconductor laser bars 27 are separated into individual semiconductor laser elements (pellets) 1 in the above-described pelletizing step after the formation of the protective films 29 and 30, the protective films 29 and 30 are peeled or cracks are formed. It is possible to effectively prevent the occurrence of troubles such as being performed.

Further, the protective film forming substance which wraps around and adheres to the electrode surfaces 10 and 12 of the semiconductor laser device (pellet) 1 stays in the cutouts 14 and 14 and does not reach the flat portion 46, so Electrode surface 1 by film forming substance
It is also possible to solve the problems that a coating is formed on the layers 0 and 12 and that mounting on a heat sink becomes difficult, and that wire bonding to the electrode surfaces 10 and 12 cannot be performed, resulting in poor conductivity and poor disconnection. .

Further, unlike the conventional method shown in FIG.
Since the spacer is not required, the semiconductor laser device (pellet) 1 can be manufactured at a low cost. In addition, since no spacer is interposed, a complicated mechanism and a precise jig are not required for aligning the plurality of semiconductor laser bars 27, so that the manufacturing process of the semiconductor laser element (pellet) 1 is simplified.

Furthermore, each semiconductor laser bar 27 is placed substantially perpendicular to the placement surface 48a of the end face coating jig 48, and is aligned so that the cleavage end face 28 is a plane orthogonal to the sputtering direction. Each semiconductor laser bar 27
Even when the width of the semiconductor laser bar varies, no shadow can be formed, and a protective film having a uniform thickness can be formed over the entire end face of each semiconductor laser bar 27.

A second embodiment of the present invention will be described with reference to FIG.

In the present embodiment, as shown in FIG. 3, notches 14 ', 14' formed at both ends in the width direction of a semiconductor laser element (pellet) 1 'have a concave groove structure.

The semiconductor laser device (pellet) 1 'of this embodiment is formed by dry etching using the resist film 23 as an etching mask instead of the above-described step of FIG. An array groove (not shown) may be formed in a rectangular cross section having a size of about 20 μm. The types of etching gas include Cl, SiCl ₄ , HB
A halogen-based gas such as r or BCl ₃ may be used.

As can be seen from FIG. 3, also in the semiconductor laser device (pellet) 1 'according to the present embodiment, the material forming the protective films 29 and 30 which wraps around and adheres to the electrode surface side is the notch portion 14', Stays in 14 'and flats 46'
Never reach. Therefore, effects similar to those of the semiconductor laser device (pellet) 1 according to the first embodiment described above can be obtained.

[0045]

According to the present invention, since no spacer is required, the manufacturing process of the semiconductor laser device can be simplified, and a low-cost semiconductor laser device can be provided.

Further, since each semiconductor laser bar is mounted perpendicular to the mounting surface of the jig, a protective film having a uniform thickness can be formed over the entire end face of each semiconductor laser bar.

Further, in the present invention, since the light emitting surface including the active layer is formed by cleavage, the light emitting efficiency is higher than when the light emitting surface is formed by etching to form the protective film.

In addition, since the same light emission amount as that of the related art can be obtained with low power consumption, the calorific value is reduced and the life of the element is prolonged.

[Brief description of the drawings]

FIG. 1 is a view showing a structure of a semiconductor laser device according to a first embodiment of the present invention, wherein FIG.
(B) is the front view, (c) is the side view.

2 (a) to 2 (k) are diagrams schematically showing a manufacturing process of the semiconductor laser device shown in FIG.

FIG. 3 is a side view of a semiconductor laser device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a conventional general semiconductor laser device.

FIG. 5 is a view showing a state in which a conventional semiconductor laser device is loaded on a jig for forming an end face protective film.

FIG. 6 is a view for explaining a conventional method for forming an end face protective film using a spacer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor laser element (pellet) 1 'Semiconductor laser element (pellet) 2 Semiconductor substrate 3 Lower cladding layer 4 Active layer 5 Upper cladding layer 6 Light emitting surface 8 Light emitting back surface 10 Electrode surface 12 Electrode surface 14 Notch 14' Notch 21 Wafer Reference Signs List 22 active layer 23 resist film 24 array groove 25 electrode 26 flaw for cleavage 27 semiconductor laser bar 28 cleavage end face 29 protective film 30 protective film 31 semiconductor substrate 32 active layer 33 clad layer 34 light emitting surface 36 light emitting back surface 38 electrode surface 40 electrode surface 44 Spacer 46 Flat part 46 'Flat part 48 End face coating jig 50 Semiconductor laser bar 54 End face coating jig 56 Mounting surface

Claims (6)

[Claims] A semiconductor substrate having first and second surfaces opposed to each other; an active layer formed on the first surface of the semiconductor substrate along one direction; and the active layer of the semiconductor substrate. A light-emitting surface and a light-emitting back surface respectively formed on both ends of the semiconductor laser device, and an electrode surface formed on the first and second surfaces, respectively, at least the light-emitting surface or the light-emitting back surface of the semiconductor substrate. A semiconductor laser device comprising a notch provided at a boundary between one surface and the second surface. 2. The semiconductor laser device according to claim 1, wherein a depth of said notch is not less than 5 μm and not more than a thickness of said semiconductor substrate. 3. A step of forming an optical resonator on a first surface of a wafer, a step of forming a plurality of arrangement grooves orthogonal to the optical resonator on a second surface of the wafer, Forming electrodes on both sides, and forming a plurality of semiconductor laser bars by cleaving along the center line in the width direction of the arrangement grooves;
A method for manufacturing a semiconductor laser device, comprising: a step of aligning the cleavage end faces of the plurality of semiconductor laser bars so as to be exposed; and a step of forming a protective film on the cleavage end faces. 4. The method for manufacturing a semiconductor laser device according to claim 3, wherein said protective film is formed by a sputtering method.
A method for manufacturing a semiconductor laser device, wherein the cleavage end faces are aligned in a direction substantially perpendicular to a sputtering direction. 5. The method of manufacturing a semiconductor laser device according to claim 3, wherein said arrangement groove is formed by etching said semiconductor substrate. 6. The method of manufacturing a semiconductor laser device according to claim 5, wherein the etching is performed by either wet etching with an acidic solution or dry etching with a halogen-based gas. Manufacturing method.