JP3203128B2 - Semiconductor laser device - Google Patents

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 such as an AlGaAs semiconductor laser device and an AlGaInP semiconductor laser device.

[0002]

2. Description of the Related Art A semiconductor laser device has a plurality of semiconductor layers including an active layer on a semiconductor substrate, and has electrodes on the lower surface of the semiconductor substrate and on a contact layer.

In general, in a semiconductor laser device, light is confined in the vertical direction by sandwiching an active layer between cladding layers having a small refractive index, and by changing the thickness of at least one of the cladding layers in the lateral direction. By causing a difference in the refractive index, light is confined in the lateral direction.

In the case of such a semiconductor laser device, when wire bonding is performed on an electrode provided on the contact layer on the oscillation region, the active layer in the oscillation region is damaged due to the impact of wire bonding, resulting in a short life and a defective product. To become
This wire bonding is performed avoiding the oscillation region.

[0005]

However, even when wire bonding is performed on the electrode on the contact layer while avoiding over the oscillation region, defective products such as short lifetimes increase even though over the oscillation region. However, a problem such as a low yield has occurred.

[0006] The present invention has been made in view of the above problems, and has as its object to provide a semiconductor laser device having a high production yield.

[0007]

A semiconductor laser device according to the present invention has a semiconductor substrate having an inclined surface, a non-flat semiconductor layer formed on the inclined surface, and a non-flat semiconductor layer formed on the non-flat semiconductor layer. A contact layer having a shape-change portion based on the inclination on the surface, and an electrode formed on the contact layer, and wire-bonding the electrode except on the shape-change portion and the oscillation region. It is characterized by.

Further, the semiconductor laser device of the present invention provides a semiconductor substrate of a first conductivity type having an inclined surface, a first cladding layer of a first conductivity type formed on the inclined surface, An active layer formed on the cladding layer, a second conductive type second cladding layer having a stripe-shaped ridge formed on the active layer, and a first conductive type formed to bury the ridge. A current blocking layer, a second conductive type contact layer formed on the current blocking layer and the ridge portion, and having a convex portion based on the slope on the surface, and an electrode formed on the contact layer, And wire-bonding to the electrode except on the protrusion and the oscillation region.

In particular, the thickness of the contact layer is 4 μm or more and 8 μm or less.

In particular, the semiconductor substrate is a GaAs substrate, and the inclined surface is a surface inclined from 1 degree to 16 degrees in the <011> direction from the {100} plane. The direction is <01-1> of the substrate.
It is characterized by being parallel to the direction.

Further, the invention is characterized in that the wire bonding is performed on the electrode on the side opposite to the inclined direction.

[0012]

The present inventor has proposed that a non-planar semiconductor layer is formed on an inclined surface of a semiconductor substrate by metal organic chemical vapor deposition (MO).
In the case of a semiconductor laser device grown by a vapor phase growth method such as a CVD method, small projections depending on the crystal growth plane orientation are formed on the contact layer surface at a position separated from the oscillation region due to a difference in manufacturing conditions. It has been found that a shape change portion occurs.

Such a shape-changed portion is minute, and it is considered that there is no problem if wire bonding is performed on this shape-changed portion. By performing the wire bonding while avoiding the change portion, the manufacturing yield is remarkably improved without shortening the element life.

In particular, when the thickness of the contact layer is 4 μm or more, it is considered that the impact at the time of wire bonding is absorbed by this layer, and the production yield is remarkably improved. If it is made in the opposite direction to the inclination direction, it is considered that the impact at the time of wire bonding may not be easily transmitted to the active layer and the like, and the production yield is significantly improved.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view schematically showing an AlGaAs-based semiconductor laser device of the present embodiment, FIG. 2 is a schematic cross-sectional view taken along a broken line AA in FIG. 1, and a dotted arrow in FIG. The direction of is shown.

In FIG. 1, reference numeral 1 denotes an n-type GaAs semiconductor substrate having a main surface 1a whose surface is inclined from the (100) plane by θ (1 ° ≦ θ ≦ 16 °) in the [011] direction, and 2 denotes a surface above the main surface 1a. A buffer layer 3 made of n-type GaAs having a layer thickness of 0.5 μm and a cladding layer 3 made of n-type Al _xa Ga _1-xa As having a layer thickness of 2 μm xa = 0.4).

Reference numeral 4 denotes an active layer made of undoped Al _q Ga _{1 -q} As and having a thickness of 0.07 μm and formed on the n-type cladding layer 3 (0 ≦ q <xa, xb: for example, the composition ratio q = 0) .
1).

Reference numeral 5 denotes a stripe-shaped width W extending 4 μm and a height 0.8 μm extending in a direction perpendicular to the paper surface of the active layer 4 (resonator length direction: [01-1] direction of the substrate 1). P-type Al _xb which is a non-flat semiconductor layer including a ridge portion 5a and flat portions 5b and 5b each having a thickness of 0.3 μm on both sides of the ridge portion.
Ga _1-xb As clad layer (for example, composition ratio xb
= 0.4), 6 is a layer thickness of 0. 0 formed on the ridge portion 5a.
2 μm p-type GaAs cap layer, 7 and 7 are ridge portions 5
a and flat portions 5b and 5b so as to embed the cap layer 6.
An n-type GaAs current blocking layer having a layer thickness of 1 μm formed thereon.

Reference numeral 8 denotes a p-type contact layer formed on the cap layer 6 and the current blocking layers 7, 7 and having a thickness of t μm on a flat portion of the current blocking layer. In the present embodiment, on the surface of the contact layer 8, a height of about 1 μm and a width of 20
A stripe-shaped convex portion (shape changing portion) 9 having a size of about μm is formed, and the separation distance is larger as the inclination angle θ or the layer thickness t of the contact layer 8 is larger.

Reference numeral 10 denotes Cr formed on the contact layer 8.
-A p-side electrode made of Au. This electrode 10 has
Through-window portion 10 located on stripe-shaped ridge portion 5a
a, 10a, and a mark portion 10b including a plurality of through holes indicating bonding positions.

Reference numeral 11 denotes a mark portion 10 of the p-type side electrode 10.
b, a bonding line made of Au or the like bonded in the mark portion 10b, the bonding portion in the mark portion 10b is in the vicinity of the ridge portion 5a and within about 10 μm from the end of the ridge portion 5a (that is, the oscillating portion and the vicinity thereof). (Oscillation region), and on the stripe-shaped projections 9. In the present embodiment, the direction is opposite to the above-mentioned inclination direction, that is, the side without the stripe-shaped convex portion 9 with respect to the ridge portion 5a.

Reference numeral 12 denotes Cr-S formed on the lower surface of the substrate 1.
This is an electrode made of n-Au, and this electrode is die-bonded to a conductive heat sink (not shown).

Next, the yield rate when the bonding wire 11 was bonded to the p-side electrode 10 of the semiconductor laser device was examined. In addition, each of the elements having the predetermined layer thickness t is 5
0 were examined.

As a result, in the case of an element having a layer thickness t of 4 μm or more, the yield rate in the case of an element having a layer thickness t of less than 4 μm is 70 to 78% (for example, when the layer thickness t is 3 μm, the yield rate is 76%). %), And a remarkably large yield rate of 86%. In particular, when the layer thickness t is 5 μm or more, the yield rate is preferably 90% or more, which is preferable.

If the layer thickness t is too large, the contact layer formation time is prolonged and the series resistance of the element is increased. Therefore, the layer thickness t is preferably 8 μm or less, more preferably 7 μm or less. is there.

Next, as a comparative example, the yield rate was examined in the same manner as in the above-mentioned element except that the layer thickness t was smaller than 4 μm and the bonding position was on the convex portion. In this case, it was worse than the case where the layer thickness t in the above-described embodiment was smaller than 4 μm.

Further, as a comparative example, the yield was examined in the same manner as in the above example except that the layer thickness t was 5 μm or more and 7 μm or less and the bonding position was on the convex portion.

As a result, the yield was poor even though the thickness t of the contact layer was a preferable value.

Further, when the bonding position is the above-mentioned inclination direction,
That is, the yield rate was examined for the same device as that of the above-described embodiment except that the ridge portion 5a was on the side where the stripe-shaped convex portion 9 was present. The layer thickness t is 4 μm or more and 8 μm.
It is as follows.

In this case, the yield was better than each of the above comparative examples, but worse than the above examples.

Therefore, in the present invention, the bonding position of the electrode on the contact layer is a position avoiding the oscillation region and the shape change portion such as the convex portion.

The thickness of the contact layer is preferably 4 μm or more and 8 μm or less, and more preferably 5 μm or more and 7 μm or less. The thickness of the contact layer according to the present invention is defined as the thickness between the flat portion of the current blocking layer and the electrode, and the contact layer does not need to be a single layer as described above.

Further, the preferred bonding position is on the side opposite to the inclined direction with respect to the oscillation region.

In particular, the inclined surface is preferably a surface inclined from the {100} surface, and the inclination angle is preferably about 16 degrees or less.

In the above description, a GaAs substrate of the first conductivity type;
AlG of the first conductivity type formed on the inclined surface of the substrate
aAs clad layer, AlG formed on the clad layer
an active layer made of aAs, and a second layer formed on the active layer.
A conductive type AlGaAs cladding layer.
Although the description has been given of the As-based semiconductor laser device, other materials are effective.

For example, a GaAs substrate of the first conductivity type and an AlGa of the first conductivity type formed on an inclined surface of the substrate.
InP clad layer, AlG formed on the clad layer
The same effect can be obtained in an AlGaInP-based semiconductor laser device including an active layer made of aInP or GaInP and an AlGaInP clad layer of the second conductivity type formed on the active layer.

In the AlGaAs-based semiconductor laser device and the AlGaInP-based semiconductor laser device, the contact layer is preferably a GaAs layer as described above, and the current blocking layer is not only a GaAs layer of the first conductivity type but also a first conductivity type. It may be an AlGaAs layer, a first conductivity type AlGaInP layer, or the like.

The main surface of the GaAs substrate has (10
Although the plane inclined in the [011] direction from the 0) plane is used and the extending direction of the stripe-shaped ridge portion is set to the [01-1] direction, it is a matter of course that an equivalent relationship may be used. That is, a plane inclined in the <011> direction from the {100} plane may be used as the main surface of the GaAs substrate, and the extending direction of the stripe-shaped ridge portion may be the <01-1> direction. In particular, AlGaAs
In the case of an s-based semiconductor laser device, the inclination angle θ is 2 degrees to
The angle is preferably 9 degrees, and in the case of an AlGaInP-based semiconductor laser device, it is preferably 5 degrees or more and 16 degrees or less.

In the present invention, the active layer may have a quantum well structure, and of course, another layer such as an etching stop layer may be provided in the cladding layer.

The width W and height of the ridge are not limited to those described above.

Furthermore, the semiconductor laser device having the above-mentioned stripe-shaped ridge portion has been described. However, other self-aligned type semiconductor laser devices having a non-flat layer under the contact layer, such as a self-aligned semiconductor laser device, are provided on the inclined surface of the substrate. As a result of the crystal growth of the semiconductor layer, the present invention can be applied to a semiconductor laser device in which a shape change portion such as a convex portion or a concave portion is formed on the contact layer surface. For example, a semiconductor substrate having an inclined surface, a non-flat semiconductor layer formed on the inclined surface, a current blocking layer formed on the semiconductor layer, and a surface formed on the current blocking layer, And a contact layer having a shape change portion based on the inclination.

Further, in the above description, the gold wire is used as the wire bonding wire. However, the present invention is not limited to this, and the wire diameter is not limited to about several tens of μm, and may be appropriately changed depending on the size of the element and the like. .

[0043]

According to the present invention, since the wire bonding is performed not only on the oscillation region but also on the shape change portion such as the convex portion, the device yield is not shortened and the production yield is remarkably improved.

In particular, when the thickness of the contact layer is 4 μm or more, it is considered that the impact at the time of wire bonding is absorbed by this layer, and the production yield is remarkably improved. If it is made on the side opposite to the inclination direction, it is considered that the impact at the time of wire bonding is difficult to propagate to the active layer and the like, and the production yield is remarkably improved.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a semiconductor laser device according to one embodiment of the present invention.

FIG. 2 is a schematic sectional view of the semiconductor laser device of the above embodiment.

[Explanation of symbols]

 Reference Signs List 1 n-type GaAs substrate 1a main surface 3 n-type cladding layer 4 active layer 5 p-type cladding layer (non-flat semiconductor layer) 5a ridge portion 5b flat portion 8 contact layer 9 convex portion (shape changing portion) 10 p-type side electrode 11 Bonding wire

──────────────────────────────────────────────────続 き Continued on the front page (72) Nobuhiko Hayashi 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) Reference JP-A-4-206983 (JP, A) JP-A 58-33885 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01S 5/00-5/50

Claims (5)

(57) [Claims] 1. A semiconductor substrate having an inclined surface, a non-flat semiconductor layer formed on the inclined surface, and a shape change portion formed on the non-flat semiconductor layer and having a surface based on the inclination. A semiconductor laser device, comprising: a contact layer having a contact layer; and an electrode formed on the contact layer, and wire-bonded to the electrode except on the shape change portion and the oscillation region. 2. A semiconductor substrate of a first conductivity type having an inclined surface, and a first conductivity type semiconductor substrate formed on the inclined surface.
A cladding layer, an active layer formed on the first cladding layer, a second cladding layer of a second conductivity type having a stripe-shaped ridge formed on the active layer, and burying the ridge. a first conductivity type current blocking layer formed, is formed on the current blocking layer and the ridge on the above the surface
A contact layer of a second conductivity type having a protrusion based on the inclination ; and an electrode formed on the contact layer, wherein the electrode is wire-bonded to the electrode except on the protrusion and the oscillation region. Semiconductor laser device. 3. The contact layer has a thickness of 4 μm or more and 8 or more.
3. The semiconductor laser device according to claim 1, wherein the thickness is not more than μm. 4. The semiconductor substrate is a GaAs substrate, wherein the inclined surface is a surface inclined from 1 degree to 16 degrees in a <011> direction from a {100} plane, and the stripe-shaped ridge portion extends 4. The semiconductor laser device according to claim 2, wherein a direction is parallel to a <01-1> direction of the substrate. 5. The semiconductor laser device according to claim 1, wherein said wire bonding is performed on said electrode on a side opposite to a direction of inclination of said inclined surface.