JP2000138414A - Manufacture of surface emission laser array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a surface emission laser array have a current constricting layer and an insulating layer both of which are free from characteristic variations in a surface emission laser array with high productivity. SOLUTION: After a first Al-containing compound semiconductor layer 20, an n-type contact layer 4, reflecting mirror layer structures 6 and 14, clad layers 8 and 12, an active layer 10, a second Al-containing compound semiconductor layer 2, and a p-type contact layer 16 are laminated upon a substrate 2, first mesa junction A extending to the boundary between the reflecting mirror layer structure 6 and contact layer 4 or to the surface of the contact layer 4 is formed from the contact layer 16 toward the lower layers, and a current constricting layer 22a having an unoxidized layer in its core section is formed by oxidizing the second Al-containing compound semiconductor layer 22 toward the core section from its sides and ends. Then second mesa junction B extending the boundary between the first Al-containing compound semiconductor layer 20 and substrate 2 or to the surface of the substrate 2 are formed from the contact layer 4 toward the lower layers, and the semiconductor layer 20 is converted into an insulating layer 20a by oxidizing the layer 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a surface emitting laser array used as a light source for optical parallel communication and optical interconnection.

[0002]

2. Description of the Related Art In recent years, a semiconductor laser array in which a large number of independently drivable lasers are arranged has been used as a light source for optical parallel communication and optical interconnection. In particular, since the surface emitting laser array can easily form a one-dimensional array or a two-dimensional array, application to these light sources is expected. This surface emitting laser array is composed of a plurality of laser elements, and each laser element is formed by epitaxially growing various semiconductors on a common substrate and stacking those films, and etching toward the lower layer with respect to the entire stacked structure formed. To form a mesa.

Here, a driving circuit for each laser element is I
Although the C circuit is used, the n-type electrode of each laser element is connected to the drive terminal of the IC circuit and the p-type electrode is kept at the same potential because the IC circuit has a driver on the minus side. By the way, for example, an n-type GaAs compound semiconductor is used for a substrate of a GaAs semiconductor laser. Therefore, in the case of an array in which the n-type substrate is used as a common substrate, the driving current of each laser element is changed to another through the n-type substrate. There is a problem that electric crosstalk occurs due to leakage into the laser element.

Therefore, it has been proposed to use a p-type GaAs compound semiconductor for the substrate.
Not only is the cost three to four times higher than the mold substrate, but also the etch pit density is high. Further, since the activation rate of Zn, which is a p-type dopant, is low, Zn may diffuse into an epitaxially grown layer to be formed in the course of epitaxial growth of a crystal, thereby deteriorating device characteristics.

On the other hand, a technique using a semi-insulating substrate in place of the n-type substrate has been proposed, but a defect added in the crystal to provide insulation may reduce the reliability of the laser. . For this reason, a technique for preventing crosstalk by forming an insulating layer between an n-type substrate and a laser element has been proposed (JH. Sin et al., IEEE Photo
n. Technol. Lett., Vol. 10, No. 6, p. 754, 1998). Laser device proposed in this prior art, on the GaAs substrate, and the DBR mirror made of AlGaAs-Al _x O _y, an active layer, a current confinement layer, AlGaAs-Al _x
Another DBR mirror of O _y has mesas stacked in this order. And this layer structure,
A precursor layer of a DBR mirror composed of AlGaAs-AlAs, an active layer, a precursor layer of a current confinement layer composed of AlAs, and another DBR composed of AlGaAs-AlAs;
The mesas having the mirror precursor layers stacked in this order are denoted by G
After being formed on an aAs substrate, it is formed by oxidizing AlAs by performing an oxidation treatment in a steam atmosphere.

That is, the AlAs layer in the precursor layer of the DBR mirror and the AlAs layer in the precursor layer of the current confinement layer.
The former is entirely oxidized into an insulating layer between the substrate and the substrate in a single oxidation treatment, and the latter is partially oxidized into a current confinement layer. This prior art utilizes the characteristic that when the Al composition ratio in an Al-containing compound semiconductor changes, the oxidation rate of the semiconductor changes, and the Al composition ratio in the AlAs layer is set to a value between the DBR mirror precursor layer and the current confinement. The insulating layer and the current confinement layer are formed at the same time by a single oxidation treatment by changing each of the layer and the precursor layer.

[0007]

However, the above prior art has the following problems. First, the first problem is that, in the case of the prior art, the insulating layer and the current confinement layer can be formed by one oxidation treatment only when the Al composition ratio of the AlAs layer is appropriately controlled. When forming the body layer, it is necessary to form the respective precursors by changing the Al composition ratio for the insulating layer and the Al composition ratio for the current confinement layer. As a result, the productivity is deteriorated, and the characteristic variation is caused. This is a problem that may occur.

A second problem is that it is difficult to manufacture a laser device having a multi-stage mesa structure which has been studied recently. This is because if a mesa having the above-described precursor structure is formed in the manufacturing process of the laser element and then exposed to the air for a long time, an oxide film is formed at a portion of the mesa where the AlAs layer or the AlGaAs layer comes into contact with the air. However, even if the above-described steam oxidation is performed on the mesa in such a state, the oxidation does not proceed further, and the insulating layer and the current confinement layer for the purpose of design cannot be formed.

The present invention solves the above-mentioned problems in the prior art. Since the Al composition ratio of the Al-containing compound semiconductor used for forming the insulating layer and the current confinement layer may be arbitrary, the productivity is high, and the multi-stage structure is improved. An object of the present invention is to provide a method of manufacturing a surface emitting laser array in which a plurality of surface emitting laser elements capable of forming mesas are integrated on the same substrate.

[0010]

In order to achieve the above object, according to the present invention, at least one surface emitting laser element is formed on a common substrate made of an n-type semiconductor. A method for manufacturing a surface-emitting laser array, wherein the surface-emitting laser element includes at least a first Al-containing compound semiconductor layer on a common substrate made of an n-type semiconductor;
a contact layer made of an n-type compound semiconductor, a first reflecting mirror layer structure, a lower clad layer made of an n-type compound semiconductor, an active layer, an upper clad layer made of a p-type compound semiconductor, a second
Al-containing compound semiconductor layer, second reflector layer structure, and p
A contact layer made of a p-type compound semiconductor is stacked in this order, and an interface between the first reflecting mirror layer structure and the contact layer made of the n-type compound semiconductor or The first mesa is formed by etching to the depth of the surface of the contact layer made of the n-type compound semiconductor, the first mesa is subjected to a first oxidation treatment, and the second mesa is formed. Al
The compound semiconductor layer is oxidized from its side end toward the core to form a current confinement layer in which the unoxidized Al-containing compound semiconductor layer remains on the core, and further comprises a lower layer from the contact layer made of the n-type compound semiconductor. Toward the interface between the first Al-containing compound semiconductor layer and the common substrate made of the n-type semiconductor or the surface layer of the common substrate made of the n-type semiconductor. After forming a second mesa located outside the side end of the first mesa, a second oxidizing process is performed, and the first mesa in the second mesa is formed.
Is completely oxidized and converted into an insulating layer, and the n-type compound semiconductor contact layer and the p-type
N-type electrode and p-type
The present invention provides a method for manufacturing a surface emitting laser array, which is manufactured by forming a mold electrode.

Further, in the present invention according to claim 2,
The surface-emitting laser device includes at least a first Al-containing compound semiconductor layer, a p-type compound semiconductor contact layer, a first reflector layer structure, and a second Al-containing semiconductor layer on a common substrate made of an n-type semiconductor. A compound semiconductor layer, a lower cladding layer made of a p-type compound semiconductor, an active layer, an upper cladding layer made of an n-type compound semiconductor, a second reflector layer structure, and a contact layer made of an n-type compound semiconductor are laminated in this order. ,
From the contact layer made of the n-type compound semiconductor to the lower layer, to the interface between the first reflector layer structure and the contact layer made of the p-type compound semiconductor or to the surface layer of the contact layer made of the p-type compound semiconductor To form a first mesa, perform a first oxidation treatment on the first mesa, and move the second Al-containing compound semiconductor layer from a side end thereof toward a core portion. Oxidation forms a current constriction layer in which an unoxidized Al-containing compound semiconductor layer remains on the core, and further, from the contact layer made of the p-type compound semiconductor to the lower layer, the first Al-containing compound semiconductor layer Of a common substrate made of n-type semiconductor and n
Etching is performed to a depth of the surface layer of the common substrate made of the mold semiconductor to form a second mesa whose side end is located outside the side end of the first mesa, and then a second oxidation is performed. A process is performed, and only the first Al-containing compound semiconductor layer in the second mesa is oxidized and converted into an insulating layer, and the n-type compound semiconductor contact layer and the p-type compound semiconductor contact layer are respectively n-type. There is provided a method for manufacturing a surface emitting laser array, which is manufactured by forming an electrode and a p-type electrode.

It is preferable that the n-type semiconductor and the compound semiconductor are GaAs, and the first Al-containing compound semiconductor layer and the second A-containing compound semiconductor layer are GaAs.
1. The surface emitting laser array according to claim 1, wherein the compound semiconductor layer comprises an AlAs layer or an AlGaAs layer, and the first reflecting mirror layer structure and the second reflecting mirror layer structure comprise a multilayer film of a GaAs layer and an AlGaAs layer. A manufacturing method is provided.

[0013]

According to the present invention, since the protective film is formed on the side surface of the current constriction layer formed by the first oxidation treatment by oxidation in the air, the second oxidation treatment is performed to form the insulating layer. In this case, the inside of the current confinement layer is not further oxidized, so that the insulating layer and the current confinement layer can be formed separately, thereby stabilizing the characteristics of the laser and improving the production yield.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, once an oxidation treatment is performed on an Al-containing compound semiconductor layer, a protective film is formed in a portion of the oxidized region which comes into contact with the atmosphere, and the protective film is formed even after steam oxidation is performed. No further oxidation proceeds towards the inside of the layer,
It was developed based on the new knowledge that
Specifically, this is a method of forming an insulating layer and a current confinement layer by two oxidation treatments.

Hereinafter, a method of manufacturing a surface emitting laser array according to the present invention will be described with reference to FIG. First, as shown in FIG. 1A, a first Al-containing compound semiconductor layer 20 and a contact layer 4 made of an n-type compound semiconductor are formed on a common substrate 2 made of an n-type semiconductor by an epitaxial growth method.
First reflector layer structure 6, lower cladding layer 8 made of n-type compound semiconductor, active layer 10, upper cladding layer 12 made of p-type compound semiconductor, second Al-containing compound semiconductor layer 2
2. A second reflector layer structure 14 and a contact layer 16 made of a p-type compound semiconductor are laminated in this order.

As the n-type semiconductor substrate 2, an InP-based compound semiconductor such as InP can be used in addition to a GaAs-based compound semiconductor such as GaAs. Examples of the n-type dopant include Si, Ge, Sn, Se, and the like. Note that a buffer layer (not shown) may be formed on the upper surface of the substrate 2. The buffer layer is for preventing crystal arrangement mismatch when various films are epitaxially formed thereon, and may be formed using the same kind of semiconductor as the substrate 2.

The first Al-containing compound semiconductor layer 20 is converted into an insulating layer mainly composed of Al oxide by a second oxidation treatment described later, thereby realizing electrical insulation between the substrate 2 and a laser element described later. Layer, for example, AlA
It is formed of an s layer or an AlGaAs layer. The contact layer 4 made of an n-type compound semiconductor and the contact layer 16 made of a p-type compound semiconductor are layers for realizing an ohmic contact with an electrode formed on an upper surface thereof as described later. These are, for example, GaAs
The s-semiconductor is doped with the above-mentioned n-type dopant to make it n-type (in the case of the contact layer 4), Zn, Cd, B
e, a p-type dopant doped with a p-type dopant such as Mg (in the case of the contact layer 16) can be used.

The first reflecting mirror layer structure 6 and the second reflecting mirror layer structure 14 constitute a resonator as a laser reflecting mirror and reduce a threshold current at the time of laser oscillation. , And a semiconductor multilayer film in which GaAs layers and AlGaAs layers are alternately stacked. In this case, it is preferable to use an n-type or a p-type semiconductor according to the polarity of the laser. For example, in the case of the laser structure shown in FIG. The mirror layer structure 14 may be p-type. Further, instead of the semiconductor multilayer film, a dielectric multilayer film or a metal thin film may be used.

The lower cladding layer 8 made of an n-type compound semiconductor, the active layer 10, and the upper cladding layer 12 made of a p-type compound semiconductor constitute a double hetero structure, and have a smaller band gap and a lower refractive index than the cladding layers 8, 12. Electrons and light are confined in the large active layer 10, and laser oscillation is performed with high efficiency. As the cladding layers 8 and 12 and the active layer 10, for example, a GaAs semiconductor may be used. Also,
The cladding layers 8 and 12 may be doped with, for example, a small amount of Al to increase the band gap as compared with the active layer 10.

In the second Al-containing compound semiconductor layer 22, a certain region from the side end toward the core is converted into an insulating layer mainly composed of Al oxide by a first oxidation treatment described later, and the core has a core. The current constriction layer 22a in which the unoxidized Al-containing compound semiconductor layer remains. Second Al-containing compound semiconductor layer 22
Is the same as in the case of the first Al-containing compound semiconductor layer 20.
It is formed of an lAs layer or an AlGaAs layer.

The above layers may be formed by, for example, molecular beam epitaxy (MBE) using an organic metal or chemical vapor deposition (MOCVD) using an organic metal. Next, a procedure for forming the first mesa will be described. First, a resist is applied to the surface of the contact layer 16 made of a p-type compound semiconductor, and a resist pattern 50 having the same cross-sectional shape as a target mesa is formed by, for example, photolithography (FIG. 1A).

Then, using this resist pattern 50 as a mask, from the contact layer 16 toward the lower layer, an interface between the first reflecting mirror layer structure 6 and the contact layer 4 made of an n-type compound semiconductor or a surface layer of the contact layer 4 is formed. The first mesa A is formed by selectively etching away the portion up to the depth (FIG. 1B). As the etching, for example, dry etching such as plasma etching or reactive ion etching can be performed.

In FIG. 1B, a first reflecting mirror layer structure 6 and a contact layer 4 made of an n-type compound semiconductor are shown.
Although the embodiment in which the etching is performed up to the interface is illustrated, the invention is not limited to such an example. In short, the etching may be performed so that the surface of the n-type contact layer 4 is exposed.
Although the illustrated first mesa A is formed in a columnar shape,
The mesa shape is not limited to this, and may be, for example, a square pillar or a triangular pillar. Further, the number of mesas A formed on the common substrate 2 is not limited to a specific number.

After the formation of the mesa A shown in FIG. 1B, a first oxidation treatment is performed. When an oxidation treatment is performed on the Al-containing compound semiconductor layer, Al in the layer becomes an oxide having an insulating property (for example, AlO _x ) from the side end toward the core.
It is known that this oxidation reaction is affected by the oxygen potential, for example, in the case of steam oxidation,
By changing the dew point of steam, the temperature, the treatment time, and the like, the rate of oxidation and the degree of oxidation can be changed.

Therefore, in the first oxidation treatment, only the second Al-containing compound semiconductor layer 22 of the first mesa A laminated structure is oxidized from its side end toward the core. However, the second Al-containing compound semiconductor layer 20 located below the contact layer 4 is not oxidized. At this time, the current constriction layer is formed by selecting the condition of the oxidation treatment so that the core portion of the second Al-containing compound semiconductor layer 22 remains in an unoxidized state.

As described above, for example, steam oxidation is preferable as the oxidation treatment. FIG. 2 is a schematic view showing an example of the current confinement layer 22a formed in this manner. The Al-containing compound semiconductor layer 25 remains at the center, and the insulating layer which is an oxide region concentric with the Al-containing compound semiconductor layer 25 is located outside. The portion 27 is formed in a columnar shape, and the current i flows intensively in the Al-containing compound semiconductor layer 25.

After forming the current confinement layer in this manner, next, the second mesa B is formed. First, a resist is applied to the surface of the first mesa A and the surface of the contact layer 4 made of the n-type compound semiconductor, and the first outer surface of the resist on the surface of the n-type contact layer 4 is larger than the first mesa A. A resist pattern 52 surrounding the mesa A is formed (FIG. 1)
(B)).

Then, using the resist pattern 52 as a mask, from the contact layer 4 to the lower layer, it reaches the interface between the first Al-containing compound semiconductor layer 20 and the common substrate 2 made of the n-type semiconductor or the surface layer of the substrate 2. The second mesa B is formed by etching to a depth of up to
(C)). Although FIG. 1C illustrates an example in which etching is performed up to the surface layer of the substrate 2, the present invention is not limited to such an example, and the point is that the surface of the substrate 2 is exposed. Etching may be performed. In FIG. 1C, the second mesa B is formed in a cylindrical shape concentrically with the first mesa A. However, the present invention is not limited to these embodiments. The first mesa A may not be concentric with the first mesa A.
The point is that the outer shape of the second mesa B should be larger than the first mesa A.

At this time, as described above, an oxide film is formed on the surface of the side edge (insulating layer portion 27) of the current constriction layer 22a in the first mesa from the time when the first oxidation process is completed. At first, before the fabrication of the second mesa B is completed, it is a dense protective film. Next, 2
The second oxidation treatment is performed. The second oxidation treatment acts on both the first mesa A and the second mesa B, and causes the current confinement layer 22a and the first Al-containing compound semiconductor layer 2 to be formed.
0 is similarly exposed to an oxidizing atmosphere. However, since a dense protective film is formed on the side surface of the current confinement layer 22a, further oxidation does not proceed in the current confinement layer 22a by the second oxidation treatment, as shown in FIG. The state is maintained. On the other hand, the side end surface of the first Al-containing compound semiconductor layer 20 is oxidized by the second oxidation treatment because the protective film as in the case of the current confinement layer 22a is not grown.

This means that, in the second oxidation treatment, only the first Al-containing compound semiconductor layer 20 can be selectively oxidized without considering further oxidation of the current confinement layer 22a. . Therefore, by appropriately selecting the conditions of the oxidation treatment, the semiconductor layer 20 is reliably oxidized all the way to the core, and the insulating layer 20a mainly composed of Al oxide is formed.
Can be converted to

As the second oxidation treatment, a steam oxidation method can be used as in the first oxidation treatment. In order to proceed oxidation to the core of the semiconductor layer 20, the first oxidation treatment is performed. In comparison, the processing temperature may be increased or the processing time may be increased. Finally, the remaining resist is removed, and an n-type electrode 30 is formed on the periphery of the n-type contact layer 4 and a p-type electrode 32 is formed on the periphery of the p-type contact layer 16 (FIG. 1).
(D)). As the n-type electrode 30, for example, Au-Ge-N
The i-alloy may be formed, for example, in a ring shape according to the peripheral shape of the mesa, using, for example, an Au—Zn alloy as the p-type electrode 32. Further, the respective p-type electrodes 32 may be connected to each other by a conductor 34 so as to have the same potential, and the respective n-type electrodes 30 may be connected to drive terminals of a control circuit (not shown).

In this manner, a surface emitting laser array in which at least one surface emitting laser element is formed on the common substrate 2 can be obtained. Although the above description has been made with respect to the invention described in claim 1, the invention described in claim 2 is substantially the same, and a description thereof will be omitted. However,
In the second aspect of the invention, the polarity of the electrodes is inverted upside down from that of the first aspect, so that the laminated structure of the first mesa is also formed upside down as the first aspect. do it.

[0033]

Embodiment 1 A laser array having the laser element structure shown in FIG.
It was manufactured according to the manufacturing method shown in FIG. 1 using MOCVD. First, the n-type GaAs common substrate 2 is subjected to a predetermined MOCVD.
The substrate is set on a susceptor of the growth apparatus, and the substrate temperature is maintained at about 600 ° C.

A carrier gas (H ₂ ) containing, for example, trimethyl gallium (TMG) as a saturated vapor is used as a Ga source, and AsH ₃ is used as a source of As.
A GaAs buffer layer 3 is grown on the substrate 2. Then, in addition to the above-mentioned Ga source and As source, a carrier gas (H ₂ ) containing, for example, trimethylaluminum (TMA) as a saturated vapor is used as the Al source on the first AlGaAs layer 20. Grow. Here, the composition of the AlGaAs layer is Al _x Ga _{1 -x} A
s (0.9 <x <1).

Next, an n-type GaAs contact layer 4 is grown by using hydrogen selenide (H ₂ Se) as an n-type dopant source in addition to the above-mentioned Ga source and As source. Further, an n-type GaAs layer is grown in the same manner as the n-type GaAs contact layer 4, and an n-type AlGaAs is formed on the n-type GaAs layer by using the above-mentioned Al source, Ga source, As source, and n-type dopant source. Grow the layer. This operation is repeated to form n-type GaAs / AlGa
A reflector layer structure 6 composed of an As multilayer film is grown. Here, the composition of the AlGaAs layer is n-type Al _y Ga _1-y As (y
≪x).

On top of this, an n-type GaAs contact layer 4
The n-type GaAs lower cladding layer 8 is grown in the same manner as described above.
The s active layer 10 is grown. In addition, in addition to the above-mentioned Ga source and As source, dimethyl zinc (DMZ) is used as a source of a p-type dopant to grow the p-type GaAs upper cladding layer 12. When growing the n-type GaAs lower cladding layer 8 and the p-type GaAs upper cladding layer 12, a small amount of Al is used by using the above-mentioned Al source.
To make the band gap larger than that of the active layer 10.

Then, in the same manner as the first AlGaAs layer 20, using the source of the above-described p-type dopant,
A second AlGaAs layer 22 is grown. Here, the second
The composition of the AlGaAs layer is p-type Al _x Ga _{1 -x} As.
(0.9 <x <1). On top of that, p-type G
p-type GaAs layer 13 in the same manner as the aAs clad layer 12
Grow.

Further, a p-type GaAs layer is grown in the same manner as the p-type GaAs cladding layer 12, and an Al source, a Ga source, an As source, and a p-type dopant source are formed thereon. An AlGaAs layer is grown. This operation is repeated to form p-type GaAs / AlGaAs
A reflector layer structure 14 composed of a multilayer film is grown. Here, the composition of the AlGaAs layer is p-type Al _y Ga _1-y As (y≪
x).

Finally, a p-type GaAs contact layer 16 is grown in the same manner as the p-type GaAs clad layer 12.
Thus, the semiconductor multilayer structure shown in FIG. 1A was obtained. Next, a resist was applied on the surface of the p-type GaAs contact layer 16, and a circular resist pattern 50 having a diameter of 30 μm was formed by photolithography. Then, using this resist pattern 50 as a mask, plasma etching is performed from the p-type GaAs contact layer 16 to the lower layer, and the first reflecting mirror layer structure 6 and the n-type Ga
A portion having a depth up to the interface of the As contact layer 4 was removed to form a cylindrical first mesa A having a diameter of 30 μm as shown in FIG.

The sample having the laminated structure was placed in a steam oxidation apparatus, and steam generated by bubbling nitrogen into water at 80 ° C. was introduced, and the sample was subjected to steam oxidation at 400 ° C. to perform the first oxidation treatment. went. As a result of this processing, as shown in FIG. 2, a region having a depth of 10 μm from the side end of the second AlGaAs layer 22 toward the core is oxidized to change into an insulating layer portion 27 mainly composed of Al oxide. At the core, a current constriction layer 22a in which an unoxidized AlGaAs layer 25 remained in a columnar shape having a diameter of about 10 μm was obtained. Reflector layer structure (6, 1
Since the Al content in 4) and the cladding layers (8, 12) was smaller than that in the second AlGaAs layer 22, they were hardly oxidized. It should be noted that the oxidation treatment
As in the GaAs layer 22 evaporates, and a small amount of Ga remains in the layer, but its composition is considered to be substantially AlO.

Next, a resist is applied to the surface of the first mesa A and the surface of the n-type contact layer 4, and the resist on the surface of the n-type contact layer 4 has a first outer shape larger than that of the first mesa A. A ring-shaped resist pattern 52 having an outer diameter of 100 μm surrounding the mesa A was formed. Then, using this resist pattern 52 as a mask, plasma etching is performed from the n-type contact layer 4 to the lower layer to remove a portion having a depth reaching the surface layer of the common substrate 2, as shown in FIG. Thus, a cylindrical second mesa B having a diameter of 100 μm and formed concentrically with the first mesa A was formed.

Then, this sample was placed in a steam oxidation apparatus, and a second oxidation treatment was performed. By making the processing time longer than that of the first oxidation treatment and completely oxidizing the first AlGaAs layer 20 and converting it into the insulating layer 20a, FIG.
A laser device having the cross-sectional structure shown by was manufactured. In this element, in a multi-stage structure composed of first and second mesas, an insulating layer 20a and a current confinement layer 2 each having predetermined characteristics are provided.
2a is formed.

Finally, the remaining resist was removed, and FIG.
As shown in (d), a ring-shaped n-type electrode 30 is formed on the periphery of the n-type contact layer 4 and a ring-shaped p-type electrode 32 is formed on the periphery of the p-type contact layer 16. The laser array of the present invention was set at the same potential by connecting at 34.

Example 2 A laser array having the laser element structure shown in FIG. 4 was manufactured in the same manner as in Example 1. In this case, the n-type electrode 3
0 is attached to the first mesa A, and the p-type electrode 32 is attached to the second mesa B, and the laminated structure of the first mesa A is upside down from that of the first embodiment. Others are the same as the embodiment. Also in this case, the insulating layer 20a and the current confinement layer 22a having predetermined characteristics can be formed.

[0045]

As is apparent from the above description, according to the method for manufacturing the surface emitting laser array of the present invention, the current confinement layer and the insulating layer are separately formed by two oxidation treatments. It is not necessary to adjust the Al composition ratio of the Al compound semiconductor layer, and an Al-containing compound semiconductor layer having an arbitrary composition can be used.

In the first oxidation treatment, only the current confinement layer is formed, and in the second oxidation treatment, only the insulating layer is formed. The insulating layer can be formed reliably,
Laser characteristic stability and manufacturing yield are greatly improved. In particular, the effects described above are significant when forming multi-stage mesas.

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for manufacturing a surface emitting laser array of the present invention.

FIG. 2 is a schematic diagram showing a structure of a current confinement layer.

FIG. 3 is a diagram showing an example of a structure of a laser element constituting a laser array manufactured by the manufacturing method of the present invention.

FIG. 4 is a diagram showing another example of the structure of the laser element constituting the laser array manufactured by the manufacturing method of the present invention.

[Explanation of symbols]

 2 Common substrate made of n-type semiconductor 4 Contact layer made of n-type compound semiconductor 6 First reflector layer structure 8 Cladding layer made of n-type compound semiconductor 10 Active layer 12 Cladding layer made of p-type compound semiconductor 14 Second Reflector layer structure 16 Contact layer made of p-type compound semiconductor 20 First Al-containing compound semiconductor layer 20a Insulating layer 22 Second Al-containing compound semiconductor layer 22a Current confinement layer 25 Al-containing compound semiconductor layer 27 Insulating layer portion 30 n Type electrode 32 p-type electrode

Claims (3)

[Claims] 1. A method of manufacturing a surface-emitting laser array, comprising forming at least one surface-emitting laser element on a common substrate made of an n-type semiconductor, wherein the surface-emitting laser element is made of an n-type semiconductor. On a common substrate, at least a first Al-containing compound semiconductor layer, a contact layer made of an n-type compound semiconductor, a first reflector layer structure, a lower cladding layer made of an n-type compound semiconductor, an active layer, and a p-type compound semiconductor An upper clad layer made of, a second Al-containing compound semiconductor layer, a second reflector layer structure, and a contact layer made of a p-type compound semiconductor are laminated in this order, and the contact layer made of the p-type compound semiconductor and the lower layer are stacked in this order. Toward the interface between the first reflector layer structure and the contact layer made of the n-type compound semiconductor or the surface layer of the contact layer made of the n-type compound semiconductor To form a first mesa, a first oxidation treatment is performed on the first mesa, and the second Al-containing compound semiconductor layer is moved from its side end toward the core. To form a current confinement layer in which an unoxidized Al-containing compound semiconductor layer remains in the core portion, and further, from the contact layer made of the n-type compound semiconductor to a lower layer, the first Al-containing compound semiconductor Etching to the depth of the interface between the layer and the common substrate made of the n-type semiconductor or the surface layer of the common substrate made of the n-type semiconductor,
After forming a second mesa whose side end is located outside of the side end of the first mesa, a second oxidation treatment is performed, and only the first Al-containing compound semiconductor layer in the second mesa is formed. Are converted to an insulating layer by oxidizing all of them, and are manufactured by forming an n-type electrode and a p-type electrode on the n-type compound semiconductor contact layer and the p-type compound semiconductor contact layer, respectively. Array manufacturing method. 2. A method of manufacturing a surface-emitting laser array comprising at least one surface-emitting laser element formed on a common substrate made of an n-type semiconductor, wherein the surface-emitting laser element is made of an n-type semiconductor. On a common substrate, at least a first Al-containing compound semiconductor layer, a contact layer made of a p-type compound semiconductor, a first reflecting mirror layer structure, a second Al-containing compound semiconductor layer, and a lower clad made of a p-type compound semiconductor A layer, an active layer, an upper cladding layer made of an n-type compound semiconductor, a second reflector layer structure, and a contact layer made of an n-type compound semiconductor, which are laminated in this order, from the contact layer made of the n-type compound semiconductor to a lower layer. Toward the interface between the first reflecting mirror layer structure and the contact layer made of the p-type compound semiconductor or the surface layer of the contact layer made of the p-type compound semiconductor To form a first mesa, a first oxidation treatment is performed on the first mesa, and the second Al-containing compound semiconductor layer is moved from its side end toward the core. To form a current confinement layer in which an unoxidized Al-containing compound semiconductor layer remains in the core portion, and further, from the contact layer made of the p-type compound semiconductor to the lower layer, the first Al-containing compound semiconductor Etching to the depth of the interface between the layer and the common substrate made of the n-type semiconductor or the surface layer of the common substrate made of the n-type semiconductor,
After forming a second mesa whose side end is located outside of the side end of the first mesa, a second oxidation treatment is performed, and only the first Al-containing compound semiconductor layer in the second mesa is formed. Are converted to an insulating layer by oxidizing all of them, and are manufactured by forming an n-type electrode and a p-type electrode on the n-type compound semiconductor contact layer and the p-type compound semiconductor contact layer, respectively. Array manufacturing method. 3. The n-type semiconductor and the compound semiconductor are GaAs, and the first Al-containing compound semiconductor layer and the second Al-containing compound semiconductor layer are an AlAs layer or an AlG
The surface emitting laser array according to claim 1, wherein the first and second reflecting mirror layer structures comprise an aAs layer, and the first and second reflecting mirror layer structures comprise a multilayer film of a GaAs layer and an AlGaAs layer. Production method.