JPH09116230A - Semiconductor light emitting device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent solder from reaching the end surface of an active layer, by making the active layer a bent surface approaching one main surface of a semiconductor substrate, toward the outside end surface, as compared with a main flat surface of the active layer, in the vicinity of the outside end surface where insulating coating of the active layer is not formed or imperfect. SOLUTION: A trench G having an U-shaped or V-shaped section is formed at a position for forming an outside end surface where insulating coating is not formed between a plurality of semiconductor laser constituting parts of a main surface 1a of a semiconductor substrate 1 or the insulating coating is imperfect. A buffer layer, a first clad layer 11, a second clad layer 12, an active layer 2 and a cap layer 3 are grown in order on the main surface 1a of the semiconductor substrate 1 containing the inside of the trench G. In this case, the active layer 2 is formed as a surface wherein the semiconductor film surface is bent along the bottom surface of the trench G. Both side end surfaces 2a, 2b of the active layer 2 which face both outside surfaces of a semiconductor chip are made distant from a fixing part 24, so that solder 23 can be prevented from reaching the end surfaces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a semiconductor light emitting device made of III-V group or II-VI group compound semiconductor or the like, for example, in a semiconductor laser, in order to enhance its heat dissipation effect, a header, an electrode on the side close to the active layer of the semiconductor laser, Electrically and thermally coupled to a heat sink or the like.

For example, as shown in the schematic sectional view of FIG. 4, a first main surface of a semiconductor substrate 1 having a first main surface is provided with a first
A conductive type first clad layer 11, for example, an undoped active layer 2, a second conductive type second clad layer 12, and a second conductive type cap layer 3 are formed, and a first electrode 21 is formed thereon.
Is formed by ohmic deposition, and the second electrode 22 is formed by ohmic deposition on the other main surface of the substrate 1, that is, the back surface.

As described above, at least the first cladding layer 11, the active layer 2 and the second cladding layer 1 are formed on the semiconductor substrate 1.
In the semiconductor laser in which 2 is formed, since the thickness of the substrate 1 is usually 100 μm or more, the distance from the active layer 2 to the second electrode 22 on the back surface of the semiconductor substrate 1 is rather large. However, since the distance from the active layer 2 to the first electrode 21 is less than 10 μm, in order to effectively dissipate the heat generated from the active layer 2, the first electrode having a small distance from the active layer 2 is required. On the 21 side, attachment is made to a mounting portion 24 having good heat conductivity, which is made of metal such as a header or a heat sink that can serve as a heat radiation path.

As shown in FIG. 4, a semiconductor laser formed by sequentially epitaxially growing a first clad layer 11, an active layer 2 and a second clad layer 12 on a flat semiconductor substrate 1 has an active layer. 2 is also formed flat. In this semiconductor laser, the light emitting end face, that is, both end faces of the active layer 2 in the cavity length direction (direction orthogonal to the paper surface in FIG. 4) is coated with an insulating film as an optical film having a required reflectance. However, the outer side end faces 2a and 2b, which are different from the outer side faces 2a and 2b, are often not substantially coated with an insulating material or partially removed in the manufacturing process to become incomplete. However, newly applying an insulative coating to these outer end surfaces 2a and 2b significantly impairs mass productivity, resulting in high cost.

By the way, when the semiconductor laser is soldered to the mounting portion 24 of the semiconductor laser by solder 23 as shown in FIG. 4, the solder 23 is pressed against the mounting portion 24 of the semiconductor laser. It is lifted with a considerably high height h along the end face of the semiconductor laser. Therefore, the solder 23 reaches the end surface of the active layer 2,
There is a problem that electrical leakage occurs, the characteristics deteriorate, and in some cases, the semiconductor laser becomes a defective product.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem of current leakage due to the swelling of the solder material in the mounting portion of the semiconductor light emitting device, for example, the semiconductor laser, that is, the mounting on the header, the heat sink, or the like.

[0008]

A semiconductor light emitting device according to the present invention, for example, a semiconductor laser, is provided on one main surface of a semiconductor substrate.
In a semiconductor laser having at least a first clad layer, an active layer, and a second clad layer, the active layer does not have an insulating coating on the active layer or is in the vicinity of an incomplete outer end face. In the above, the curved surface is formed so as to be closer to the other main surface of the semiconductor substrate, as compared with the main surface of the active layer, toward the outer end surface.

Further, in the method of manufacturing a semiconductor device such as a semiconductor laser according to the present invention, the outer end surface of the one main surface of the semiconductor substrate, on which the insulating coating of the finally formed semiconductor laser is not formed or is incomplete, is formed. A step of forming a groove at a position corresponding to the portion, a step of epitaxially growing at least a first cladding layer, an active layer, and a second cladding layer including the inside of the groove of the semiconductor substrate; And a dividing step of dividing at a position having a groove.
Then, the outer end face is formed by the divided cross section, and the active layer is closer to the outer end face in the vicinity of the outer end face, and the active layer is closer to the other main face of the semiconductor substrate than its main plane. A semiconductor light emitting device having a curved surface, for example, a semiconductor laser is configured.

According to the semiconductor light emitting device such as a semiconductor laser and the manufacturing method thereof according to the present invention as described above, the insulating coating on the end face of the active layer is not formed or the incomplete outer end face approaches the semiconductor substrate side. Therefore, even if a semiconductor light emitting device such as a semiconductor laser is soldered to its mounting portion such as a header or a heat sink on the side opposite to the semiconductor substrate, that is, the surface closer to the active layer, It is possible to avoid the disadvantage that the solder reaches the outer end surface, which is a problem of the layer, and causes the problem of leakage.

[0011]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic sectional view of an example of a semiconductor light emitting device according to the present invention, for example, a semiconductor laser,
3 and 3 are cross-sectional views of respective steps of an example of the manufacturing method of the present invention.

An example of application to, for example, an AlGaAs semiconductor laser will be described. In this case, as shown in FIG. 2, a semiconductor substrate 1 made of a single crystal GaAs substrate having the first conductivity type, that is, n type or p type is used. prepare. This substrate 1 is usually composed of a wide area semiconductor wafer capable of simultaneously forming a plurality of semiconductor lasers. Then, in the main surface 1a of the semiconductor substrate 1, between the constituent portions of the plurality of semiconductor lasers, particularly, in the case where the insulating coating is not finally formed or the position where the outer end surface where the insulating coating is incomplete is formed, for example, Finally, a groove G having a U-shaped or V-shaped cross section, for example, is formed in a portion forming both outer end surfaces in the direction along the width direction of the laser.

Thereafter, the semiconductor substrate 1 including the inside of the groove G is
If necessary, GaAs, AlGaA on the main surface 1a of
A buffer layer (not shown) of s or the like is formed, and AlG of the first conductivity type, that is, the same conductivity type as the substrate 1 is sequentially formed thereon.
The first clad layer 11 made of aAs and the active layer 2 made of AlGaAs or GaAs having a non-doped or low impurity concentration and a smaller amount of Al than the clad layer.
And a second conductivity type, for example, p-type or n-type AlGaA
second cladding layer 12 made of s and Ga of the second conductivity type
The cap layer 3 made of As is sequentially formed, for example, by MOCVD.
Epitaxial growth is performed by the (Metal Organic Chemical Vapor Deposition) method.

At this time, the depth and sectional shape of the groove G are selected such that at least the active layer 2 is formed as a curved surface of the semiconductor film along the bottom surface of the groove G.

Although not shown, an insulating film is formed on the cap layer 3 as needed, and a stripe is formed on a portion of the insulating film which finally constitutes a stripe resonator of the semiconductor laser. -Shaped electrode contact window is formed, and one electrode, for example, the first electrode 21 is brought into ohmic contact with the cap layer 3 through the contact window.

On the back surface of the semiconductor substrate 1, that is, on the main surface opposite to the main surface 1a on which each semiconductor layer is epitaxially grown, the other electrode, for example, the second electrode 22 is ohmicly deposited.

In FIG. 3, a position indicated by a chain line a, that is, a groove G
The substrate 1 having the respective semiconductor layers 11, 2, 12 and 3 is separated along a substantially central part thereof by a well-known method such as scoring and breaking and divided into semiconductor lasers to form semiconductor chips. In this case, end surfaces 2a and 2b facing the outer surface of the chip on the width direction side of the stripe-shaped resonator are formed in the dividing plane of the groove G, and end surfaces in the resonator length direction orthogonal to this are formed, that is, the light emitting end surface ( Figure 1
3 to 3) is formed by, for example, a cleavage plane of a crystal, and an optical film having a required reflectance by an insulating film is usually coated on the end face.

This semiconductor laser chip is shown in FIG.
As shown in FIG. 3, the mounting portion 24, for example, a header, a heat sink, or the like is soldered with the solder 23.

In the semiconductor laser according to the present invention thus formed, as shown in FIG. 1, both end faces 2a and 2b of the active layer 2 different from the end face in the cavity length direction are
Compared to the main plane of the active layer 3, that is, the plane along the main surface 1a of the semiconductor substrate 1, the active layer 2 has its both end surfaces 2a and 2b so as to be closer to the other main surface 1b of the semiconductor substrate 1.
It becomes a curved surface in the vicinity of. That is, both end faces 2a and 2b of the semiconductor chip, which are located in the width direction of the stripe laser resonator of the active layer and face both outer surfaces, are lifted in a direction away from the mounting portion 24 as compared with the central portion of the active layer. Is formed so as to be in a fixed position.

Therefore, according to this structure, as shown in FIG. 1, the end faces 2a and 2b of the active layer 3 are located above the swell of the solder 23 over the height h of the side surface of the semiconductor laser. can do. With such a configuration, it is possible to prevent the solder 23 from reaching the end faces 2a and 2b of the active layer 3,
This makes it possible to avoid the occurrence of leakage due to the adhesion of solder to the active layer 2.

In the above example, the end faces 2a and 2b of the semiconductor chip in the width direction of the resonator are attached to the mounting portion 2.
Although the configuration is such that the active layer 3 is separated from the active layer 3, the active layer 2 may have a shape in which the surfaces of the active layer 2 are curved in the vicinity of the end surfaces of the active layer 3 in the cavity length direction.

In the above-mentioned example, the active layer 2 is applied to a double heterojunction type semiconductor laser sandwiched by the first cladding layer 11 and the second cladding layer 12. Not limited to semiconductor lasers,
For example, an SCH (Separat) in which at least one of the active layers is sandwiched by a clad layer via a guide layer.
The present invention can be applied to semiconductor lasers having various configurations such as e-fine structure (heterostructure) structure, and further to light emitting semiconductor devices such as light emitting diodes.

Further, in the above-mentioned example, the present invention is applied to a single-beam semiconductor laser in which one resonator is formed in one semiconductor chip, that is, one light-emitting section, but a multi-beam type having a plurality of light-emitting sections is used. In a semiconductor laser,
The present invention can also be applied.

In this case, between the light emitting parts, as shown in FIG.
The groove G shown in is formed, and the semiconductor substrate is not broken in the groove G between the light emitting portions.

Further, in the above-mentioned example, the present invention is applied to a semiconductor light emitting device such as a semiconductor laser having a so-called horizontal resonator structure formed in a direction in which the laser resonator length direction is mainly along the plate surface of the substrate 1. In some cases, the same effect can be obtained by applying the present invention to a so-called surface emitting laser in which the thickness direction of the active layer is the cavity length direction.

Further, the present invention is not limited to the AlGaAs semiconductor light emitting device, but a III-V group compound semiconductor light emitting device such as an AlGaInP semiconductor laser, and II.
It goes without saying that it can be applied to a -VI compound semiconductor laser. That is, the present invention is not limited to the above-described example, but various modifications and changes can be made.

[0027]

As described above, according to the present invention, the end face, for example, the outer end face in the width direction of the laser cavity where the active layer is not coated with the insulating layer or is insufficient, is provided in the vicinity of this outer end face. By curving the surface of the active layer, these outer end surfaces are kept away from the mounting portion side of the semiconductor light emitting device, that is, for example, the semiconductor laser, so that the occurrence of leakage due to the rise of solder in the mounting portion is avoided. As a result, it is possible to reduce the deterioration of characteristics and the occurrence of defective products.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an example of a semiconductor light emitting device according to the present invention.

FIG. 2 is a schematic cross sectional view in a step of an example of the method for manufacturing the semiconductor light emitting device according to the present invention.

FIG. 3 is a schematic cross-sectional view in another step of the example of the method for manufacturing the semiconductor light emitting device according to the present invention.

FIG. 4 is a schematic cross-sectional view of a conventional semiconductor light emitting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Active layers 2a, 2b End surface 3 Cap layer 11 First clad layer 12 Second clad layer 21 First electrode 22 Second electrode 23 Solder 24 Attachment part

Claims (2)

[Claims] 1. A semiconductor light emitting device in which at least a first cladding layer, an active layer, and a second cladding layer are formed on one main surface of a semiconductor substrate, wherein the active layer is the active layer. In the vicinity of the outer end surface where the insulating coating is not formed or is imperfect, a curved surface that is closer to the other main surface of the semiconductor substrate as compared with the main surface of the active layer toward the outer end surface. A semiconductor light emitting device characterized by the above. 2. A step of forming a groove on one main surface of a semiconductor substrate at a position corresponding to a formation portion of an outer end surface where an insulating coating of a semiconductor light emitting device to be finally formed is not formed or is incomplete. A step of epitaxially growing at least a first clad layer, an active layer and a second clad layer in the groove of the semiconductor substrate, and a step of dividing the semiconductor substrate at a position having the groove The outer end face is formed by the divided surface, and the active layer is closer to the outer end face in the vicinity of the outer end face than the main plane of the active layer and is the other one of the semiconductor substrates. A method of manufacturing a semiconductor light-emitting device, characterized in that the curved surface is close to the main surface.