JPH11274654A - Semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the main face of a silicon substrate from being inclining from a vertical direction and to improve the lift reception efficiency of a laser output detection photodiode, when a groove where a slope is formed on the silicon substrate of a face (100) by a face (111) and one slope is set to be a reflection mirror face reflecting emitted light from a semiconductor laser chip. SOLUTION: A groove formed by a face (111) is formed on the silicon substrate 20 of a face (100) having the off angle of 5-15 degree with a direction (100) as an axis. A face whose inclination is approximated to 45 degrees is set to be a reflection mirror face 21. A part of the main face 33 of the silicon substrate on a side facing the face is made to be lower than a peripheral main face 32 so as to form a recessed part. A semiconductor laser chip 13 is fixed so that an output face becomes parallel to the upper end ridge line of a face facing the reflection mirror face 21. A laser output detection photodiode is formed in a step part at the back of the semiconductor laser chip 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor laser device used for optical information processing, optical measurement, optical communication and the like.

[0002]

2. Description of the Related Art A conventional semiconductor laser device will be described with reference to a sectional view shown in FIG.

In this structure, a heat sink 2 is fixed above one side surface of an element fixing base 1, a semiconductor laser chip (hereinafter referred to as a laser chip) 3 is fixed thereon, and a light emitting surface of the laser chip 3 and a heat sink 2 are fixed. The laser output light detecting photodiode 4 is mounted on the side opposite to the light emitting surface of the laser chip 3, and the signal detecting photodiode 5 is mounted on the upper surface of the element fixing base 1. Is placed.

Next, the operation of this structure will be described. The emitted light 6 emitted from the laser chip 3 to the upper side of the drawing is reflected by the object, input to the photodiode 5 for signal detection as reflected light 7, and subjected to signal processing. On the other hand, the laser light emitted from the opposite side of the emission light surface of the laser chip 3 is input to the laser output light detecting photodiode 4, and is converted into a current signal corresponding to the intensity of the laser light. This signal is fed back to the laser chip drive circuit to stably control the output of the laser light.

In this conventional configuration, the signal detecting photodiode 5 and the laser output light detecting photodiode 4 are fixed in a plane that is horizontal and nearly horizontal with respect to the element fixing base 1, while the laser chip 3 Must be fixed in a vertical plane, the assembly work efficiency is poor, and there is a major problem in alignment accuracy.

As a structure for solving this problem, there is a semiconductor laser device as shown in a sectional view of FIG.

In this structure, a V-shaped groove whose both slopes are formed by the (111) plane is formed in the (100) plane silicon substrate 8, and one of the slopes of the groove is formed by the laser emission light. The main surface of the silicon substrate 8 on the side facing the mirror surface 9 is made lower than the other main surface, and the lowered main surface of the silicon substrate intersects the slope of the V-shaped groove. The laser chip 3 is fixed so that the front end face from which the laser light of the laser chip 3 is emitted is parallel to the ridge line.

According to this structure, the laser chip 3
The emitted light emitted in the horizontal direction is reflected by the reflecting mirror surface 9 and can be taken out substantially upward. This allows
A photodiode for signal detection (not shown) or a photodiode for laser output light detection (not shown) can be mounted on the main surface of the silicon substrate 8, and the alignment accuracy can be improved.

[0009]

When a V-shaped groove whose slope is formed by the (111) plane is formed in the (100) plane silicon substrate 8, the reflection mirror surface 9 of the groove and the surface of the silicon substrate 8 are formed. Is about 55 °, the center axis of the emitted light is about 20 ° from the direction perpendicular to the main surface of the silicon substrate.
There was a problem of tilting.

In addition, there has been a problem that photodiodes for various uses have to be mounted on a silicon substrate, which complicates an assembling process.

[0011]

According to the semiconductor laser device of the present invention, a (100) plane silicon substrate having an off angle of 5 to 15 ° with respect to the <110> direction is formed on a (100) plane silicon substrate, and both side slopes are (111) planes. A groove formed by the surface is formed, and the slope of the groove with respect to the surface of the silicon substrate is 4 °.
A surface close to 5 ° is a reflecting mirror surface for reflecting the laser beam, and a part of the main surface of the silicon substrate facing the surface is lower than the surrounding main surface to form a concave portion. The semiconductor laser chip is fixed to the concave portion of the silicon substrate so that the front end face of the semiconductor laser chip is parallel to the upper edge line of the surface facing the semiconductor chip, and the semiconductor on the silicon substrate to which the semiconductor chip is fixed is fixed. A photodiode for detecting laser output light is formed in a step portion of a concave portion behind a laser chip.

According to this structure, since the main surface of the silicon substrate is a surface provided with an off-angle of 5 to 15 degrees from the (100) plane, the inclined surfaces on both sides are formed by the (111) plane. The angle θ between the reflection mirror surface and the main surface of the silicon substrate can be in the range of 40 ° ≦ θ ≦ 50 °.
Therefore, the central axis of the laser light emitted from the laser chip after being reflected by the reflection mirror surface can be made substantially perpendicular to the main surface of the silicon substrate.

Further, since the laser output light detecting photodiode is formed at the step portion behind the semiconductor laser chip, most of the light output from the rear of the laser chip is received by the laser output light detecting photodiode. Therefore, monitoring with very high detection sensitivity is possible.

[0014]

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

(First Embodiment) A first embodiment of a semiconductor laser device according to the present invention will be described with reference to the perspective view shown in FIG. 1 and a cross-sectional view taken along line AA.

This is because a V-shaped groove in which both inclined surfaces are formed by the (111) plane on the (100) plane silicon substrate 10 having an off angle of about 10 ° with the <110> direction as the rotation axis. (Hereinafter referred to as V-grooves) 11 are formed, and of these slopes, the inclination θ with respect to the surface of the silicon substrate 10 is formed.
Is the reflection mirror surface 12, and the main surface 33 of the silicon substrate on the side facing this surface is the other main surface 3.
2, and the laser chip 13 is fixed to the surface of the silicon substrate 10 such that the front end face of the semiconductor laser chip 13 is parallel to the upper edge of the groove on the surface facing the reflection mirror surface. is there. Note that a gold thin film 14 of 3000 to 5000 ° is formed on the surface of the reflection mirror surface 12, and the reflectance of the mirror is 90% or more. Further, the laser chip 13 is fixed with a solder material so that the light emitting portion is on the lower side.

With this structure, the laser light emitted from the laser chip 13 in the horizontal direction is reflected by the reflection mirror as shown by the optical path 15, travels in the vertical or near vertical direction, and is extracted as output light.

The (100) plane having an off angle of about 10 ° was used as the surface of the silicon substrate.
It has an off-angle of 5 to 15 ° in actual use (10
0) plane. At this time, the inclination θ of the reflection mirror surface with respect to the surface of the silicon substrate can be kept within the range of 40 ° ≦ θ ≦ 50 °.

The same can be said for the other embodiments described later. (Embodiment 2) Next, a second embodiment of the semiconductor laser device of the present invention will be described with reference to a perspective view and a sectional view shown in FIG.

This is because the area of the main surface 33 which is lower than the main surface 32 of the (100) plane of the silicon substrate 10 provided with the off-angle described in FIG. The structure is not limited to this, and at least a region in which the laser chip 13 can be accommodated. The structures of the reflection mirror surface 12 and the semiconductor laser chip 13 are as described with reference to FIG.

(Embodiment 3) Next, a third embodiment of the semiconductor laser device of the present invention will be described with reference to the sectional view shown in FIG.

The V-groove shown in FIG. 1 is formed on a (100) plane P-type silicon substrate 20 having an off-angle of about 10 ° with the <110> direction as a rotation axis. A reflection mirror surface 21 for reflecting a laser beam is formed on a surface having a groove whose inclination with respect to the surface of the silicon substrate 20 is closer to 45 °.
The main surface 33 of the silicon substrate facing this surface is made lower than the other main surface 32, and the n-type diffusion region 22 is formed on the P-type silicon substrate 20 side of the reflection mirror surface. An insulating silicon oxide film 23 and a gold thin film 24 are laminated on the surface 21, and the laser chip 13 is placed such that the front end surface of the laser chip 13 is parallel to the upper edge of the surface facing the reflection mirror surface 21. The structure is fixed to the silicon substrate 20.

The thickness of the gold thin film 24 is set to 500 to 100.
This is a structure in which a semi-transmissive film is set as 0 °, and a part of the laser light is incident on a photodiode constituted by the P-type silicon substrate 20 and the n-type diffusion region 22.

With this structure, a part of the laser light emitted in the horizontal direction from the laser chip 13 passes through the semi-transmissive film formed of the gold thin film 24 and enters the photodiode, and the rest is a semi-transmissive film. The reflected light travels in the vertical or nearly vertical direction as shown in the optical path 25, and is extracted as output light.

The light incident on the photodiode is converted into a current signal according to the light intensity, and this current signal is fed back to the laser chip driving circuit and used to keep the output of the laser light constant. You.

Embodiment 4 Next, a fourth embodiment of the semiconductor laser device of the present invention will be described with reference to the sectional view shown in FIG.

The V-groove shown in FIG. 1 is formed on a (100) plane P-type silicon substrate 20 having an off angle of about 10 ° with the <110> direction as a rotation axis. A reflection mirror surface 21 for reflecting a laser beam on a surface having a groove whose inclination with respect to the surface of the silicon substrate 20 is close to 45 °.
The main surface 33 of the silicon substrate on the side facing this surface is lowered with respect to the other main surface 32 so that the front end surface of the laser chip 13 is parallel to the upper edge of the surface facing the reflection mirror surface. The laser chip 13 is fixed to the silicon substrate 20, and the n-type diffusion region 26 is formed over the step formed by the main surface 32 and the main surface 33 of the P-type silicon substrate 20 behind the laser chip 13.

P-type silicon substrate 20 and n-type diffusion region 26
The photodiode formed by receives most of the laser light emitted from the rear end face of the laser chip 13 and generates a current signal converted according to the light intensity. This current signal is fed back to the laser chip drive circuit, and is used for monitoring to keep the intensity of the laser light emitted from the front end face of the laser chip 13 constant. By forming the photodiode at the step portion in this manner, most of the laser light can be received, so that monitoring with extremely high detection sensitivity can be made possible.

The laser light emitted in the horizontal direction from the front end face of the laser chip 13 is reflected by the reflecting mirror surface 21 coated with the gold thin film, travels vertically or almost vertically, and is extracted as output light. .

Reference numeral 27 denotes an optical path of laser light emitted from the rear end face of the laser chip 13, and reference numeral 28 denotes an optical path of laser light emitted from the front end face of the laser chip 13.

Embodiment 5 Next, a fifth embodiment of the semiconductor laser device of the present invention will be described with reference to the perspective view shown in FIG.

This structure has a (100) plane P with an off angle of about 10 ° with the <110> direction as a rotation axis.
V-grooves 11 are formed on the silicon substrate 20 on both sides of which are formed by (111) planes. Of these inclined planes, the reflection mirror surface 12 whose inclination with respect to the surface of the silicon substrate 20 is closer to 45 °, The main surface 33 of the silicon substrate on the side opposite to this surface is lowered with respect to the other main surface 32 so that the front end surface of the laser chip 13 is parallel to the upper edge of the groove on the surface facing the reflection mirror surface. Silicon substrate 20
The laser chip 13 is fixed on the surface of the
A laser output light detecting photodiode 29 is formed by forming an n-type diffusion region in a step portion behind 3
Further, a photodiode 30 for signal detection is formed on a silicon substrate 20.

With this configuration, the laser light emitted in the horizontal direction from the front end face of the laser chip 13 is reflected by the reflecting mirror surface 12 coated with the gold thin film, and as shown in the optical path 15, in the vertical or nearly vertical direction. And the light is extracted as output light. The signal light 31 whose output light is reflected by the object is input to the signal detection photodiode 30,
The signal is processed. On the other hand, the laser light emitted from the rear end face of the laser chip 13 is input to the laser output light detecting photodiode 29 and is converted into a current signal according to the light intensity. This current signal is fed back to the laser chip drive circuit, and is used to make the output of the laser light emitted from the front end face of the laser chip constant.

According to this structure, the laser output light detecting photodiode 29 and the signal detecting photodiode 30
Are formed on the same substrate, so that they can be compactly integrated.

In the embodiment, the photodiodes for detecting the laser output light and for detecting the signal have been described. However, the present invention is not limited to this, and an amplifier circuit for a signal obtained from the photodiode, a driving circuit for a laser chip, and An optical signal processing circuit and the like can be formed over the same substrate.

[0036]

According to the semiconductor laser device of the present invention,
Using a (100) silicon substrate having an off angle of 5 to 15 ° with respect to the <110> direction as an axis, grooves formed on both sides by the (111) plane are formed.
One of the (111) planes has an inclination of about 45 ° with respect to the surface of the silicon substrate, and this plane can be used as a reflection mirror surface. Since the semiconductor laser chip is fixed to the silicon substrate so that the front end face of the chip is parallel, the laser light emitted from the laser chip in the horizontal direction is reflected by the reflection mirror surface and can be taken out almost vertically. The alignment of the emission direction can be simplified.

In addition, since the concave portion is formed by lowering a part of the main surface of the silicon substrate on the side facing the reflecting mirror surface than the surrounding main surface, the reflection of the laser output light on the reflecting mirror surface is increased. And increase efficiency.

Also, since the laser output light detecting photodiode is formed at the step portion of the concave portion behind the semiconductor laser chip, most of the light output from the rear of the laser chip can be used for the laser output light detecting photodiode. , The detection sensitivity can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view and a cross-sectional view of a semiconductor laser device of the present invention having a V-groove and a region where the main surface of a silicon substrate is lowered.

FIG. 2 is a perspective view and a cross-sectional view of a semiconductor laser device according to the present invention in which a region whose main surface is lowered is limited to a region where at least a laser chip can be stored;

FIG. 3 is a cross-sectional view of a semiconductor laser device of the present invention in which a photodiode is formed on a reflection mirror surface side.

FIG. 4 is a cross-sectional view of a semiconductor laser device of the present invention in which a photodiode is formed at a step portion behind a laser chip.

FIG. 5 is a perspective view of a semiconductor laser device of the present invention in which various elements are formed on a silicon substrate on which a laser chip is mounted.

FIG. 6 is a sectional view of a conventional semiconductor laser device in which a laser chip is mounted on a fixed base.

FIG. 7 is a sectional view of a conventional semiconductor laser device in which a laser chip is mounted on a silicon substrate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Silicon substrate 11 V-shaped groove (V groove) 12, 21 Reflection mirror surface 13 Semiconductor laser chip 14, 24 Gold thin film 15, 25 Optical path 20 P-type silicon substrate 22, 26 n-type diffusion region 23 Silicon oxide film 27 Laser chip Optical path of laser light emitted from rear end face 28 Optical path of laser light emitted from front end face of laser chip 29 Photodiode for detecting laser output light 30 Photodiode for detecting signal 31 Signal light 32 Main surface of silicon substrate 33 Reduced silicon Main surface of substrate

Continuing from the front page (72) Inventor Yuichi Shimizu 1-1, Komachi, Takatsuki-shi, Osaka Matsushita Electronics Corporation

Claims (1)

[Claims] 1. An angle of 5 ° to 15 ° about a <110> direction as an axis.
On the (100) silicon substrate having the off-angle of (1), a groove is formed in which both slopes are formed by the (111) plane, and the slope of the slope with respect to the silicon substrate surface is close to 45 °. The surface is a reflection mirror surface for reflecting the laser light, and a part of the main surface of the silicon substrate on the side facing the reflection mirror surface is made lower than the surrounding main surface to form a recess, and the concave surface is opposed to the reflection mirror surface. The semiconductor laser chip is fixed to the concave portion of the silicon substrate so that the front end surface of the semiconductor laser chip is substantially parallel to the upper edge line of the surface to be formed, and the semiconductor on the silicon substrate to which the semiconductor laser chip is fixed is fixed. A semiconductor laser device, wherein a laser output light detecting photodiode is formed in a step portion of a concave portion behind a laser chip.