JPH10223975A - Surface emission type semiconductor laser device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the contact resistances of the electrodes of a semiconductor laser device by forming a heaving doped area containing an impurity of the same conductivity as that of a lower multilayered semiconductor reflecting film in a section where no optical waveguide is formed including the lower multilayered semiconductor reflecting film exposed in an opening. SOLUTION: A cylindrical light control area is formed by successively forming an n-type Al0.9 Ga0.1 As/Al0.3 Ga0.7 As upper multilayered semiconductor reflecting film 9 and an n-type GaAs protective layer 10 and etching off the film 9 and layer 10 except the parts of the film 9 and layer 10 above a light emitting area. The contact resistances of electrodes are reduced by etching off the film 9 from the partial surface of the removed area of the reflecting film 9 to the depth reaching the surface of a p-type lower multilayered semiconductor reflecting film 2 and forming a p-type impurity diffusion area 3 containing beryllium(Be) at a high carrier concentration of 1×10<19> cm<-3> on the surface of the reflecting film 2 and an ohmic contact with a p-side electrode 11 formed on the area 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-emitting type semiconductor laser device and a method of manufacturing the same, and more particularly to a surface-emitting type semiconductor laser device used as a light source for optical communications, optical recording devices, laser printers and the like.

[0002]

2. Description of the Related Art In recent years, in a surface emitting laser in which a resonator is formed perpendicularly to a substrate, an electrode is formed on a semiconductor multilayer reflective film near an active layer as means for injecting current into an active layer in a minute area. A so-called intra-cavity surface-emitting type semiconductor laser device in which a current flows from the electrode to the active layer has been actively studied. In this method, the current is caused to flow as little as possible through the semiconductor multilayer mirror whose resistance is increased by the band offset, so that the generation of Joule heat is suppressed, and the deterioration of the laser characteristics due to the heat can be reduced. Such a surface-emitting type semiconductor laser device is, for example, an IEEE Journal of Quantum Elec
tronics, Vol. 29, No. 5, 1295 (1993), FIG. 11.

As shown in FIG. 29, this surface-emitting type semiconductor laser device has a p-type GaAs substrate
-Type lower semiconductor multilayer reflective film 2, p-type lower spacer layer 4, active layer 5, n-type upper spacer layer 6, n-type AlAs layer 7, and current confinement layers 8, n formed by selective oxidation thereof.
Mold upper semiconductor multilayer reflective film 9 and protective film 10 are sequentially laminated,
A semiconductor pillar is formed, and a part of the n-type upper semiconductor multilayer reflective film 9 around the semiconductor pillar is selectively removed.
A side electrode 12 is formed, and a p-side electrode 11 is further formed so as to be in contact with the p-type lower semiconductor multilayer reflective film 2 therearound. According to such a configuration,
Since the p-side electrode and the n-side electrode are formed on the semiconductor multilayer reflective film closer to the active layer and the current confinement layer 8 is formed, current can be more efficiently injected into the active layer. It has become.

In manufacturing the surface emitting semiconductor laser device, first, as shown in FIG. 30, a lower semiconductor multilayer reflective film 2 is formed on a p-type GaAs substrate 1 by metal organic chemical vapor deposition (MOCVD). Lower spacer layer 4, triple quantum well structure active layer 5, n-type upper spacer layer 6, n-type AlA
The s layer 7, the n-type upper semiconductor multilayer reflective film 9, and the protective film 10 are sequentially laminated.

Then, by photolithography,
As shown in FIG. 31, a resist pattern 13 is formed,
Using this resist pattern as a mask, the upper semiconductor multilayer reflective film 9 is selectively etched away.

Further, a second photolithography is performed to form a resist pattern 13 as shown in FIG. 32, and the resist pattern is used as a mask to selectively remove the lower semiconductor multilayer reflective film 2 by etching until the lower semiconductor multilayer reflective film 2 is exposed.

After that, photolithography is further performed, and as shown in FIG.
And a resist pattern 13 having an overhang shape is formed so as to cover other regions except for a part of the p-type lower semiconductor multilayer reflective film 2.

[0008] Then, an electrode material is formed on the upper layer, and the p-side electrode 11 and the n-side electrode 12 are formed by lift-off, whereby the surface-emitting type semiconductor laser device shown in FIG. 29 is formed.

[0009]

However, this surface-emitting type semiconductor laser device has the following disadvantages. That is, in this structure, the electrodes are formed directly like the semiconductor multilayer reflective film, but in order to suppress absorption by free carriers, the doping concentration of the semiconductor multilayer reflective film is set to
There is a problem that the contact resistance cannot be made high enough to sufficiently lower the contact resistance. For this reason, there has been a problem that a Schottky junction tends to be formed instead of an ohmic contact.

This is particularly remarkable when forming a contact with the p-type semiconductor multilayer reflective film, and this has been a cause of preventing improvement in laser characteristics.

In addition, since the semiconductor multilayer reflective film is slightly oxidized by the oxidation of the AlAs layer 7, when the electrodes are formed, they are closer to Schottky junctions.

The present invention has been made in view of the above circumstances, and has as its object to provide a surface-emitting type semiconductor laser which is easy to manufacture, has high reproducibility, reduces contact resistance of electrodes, and has high luminous efficiency. .

[0013]

Therefore, a first feature of the present invention is that at least a lower semiconductor multilayer reflective film, an active layer, and an upper semiconductor multilayer reflective film are sequentially laminated on a substrate,
A semiconductor columnar structure composed of an upper multilayer reflective film is selectively formed on the light emitting region, a first electrode is formed near the semiconductor columnar structure so as to contact the upper multilayer reflective film, and a lower electrode is further formed. In a surface-emitting type semiconductor laser device in which an opening is formed so that a semiconductor multilayer reflective film is exposed and a second electrode is formed in a portion where an optical waveguide including a lower semiconductor multilayer reflective film exposed in the opening is not formed. And forming a high-concentration impurity region containing impurities of the same conductivity type as the lower semiconductor multilayer reflection film at a high concentration. In the p-type region, it is particularly difficult to form an ohmic contact because an electrode and a Schottky barrier are easily formed. However, according to this configuration, an ohmic contact can be easily formed. Therefore, it is particularly effective when the lower semiconductor multilayer reflective film is formed of a p-type semiconductor layer.

Still preferably, the high-concentration impurity region extends from the opening to a position immediately below the semiconductor pillar and in the vicinity of a partial central region serving as a light-emitting region defined by a current confinement layer. Have been.

Preferably, a current confinement layer for defining a current path is formed above or below the active layer, and an edge of the current confinement layer for defining a current path and an end of the high-concentration impurity region are formed. It is characterized in that they are configured to substantially match.

According to a second aspect of the present invention, on a semiconductor substrate,
A first conductive type lower semiconductor multilayer reflective film, a semiconductor active layer,
A semiconductor layer laminating step of sequentially laminating an upper semiconductor multilayer reflective film of the second conductivity type, selectively removing at least a portion of the upper semiconductor multilayer reflective film to form a semiconductor columnar region, and further in the vicinity thereof An etching step of selectively etching and removing the semiconductor active layer to expose the lower semiconductor multilayer reflective film, and a portion of the upper semiconductor multilayer reflective film near the semiconductor columnar region and further exposed to the vicinity thereof. An electrode forming step of forming first and second electrodes, respectively, so as to contact the lower semiconductor multilayer reflective film. After the formation of the semiconductor active layer, prior to the electrode forming step, Including an impurity introducing step of introducing a first conductivity type impurity into the surface of the lower semiconductor multilayer reflective film at a high concentration to form a high concentration impurity region. Preferably, the upper or lower semiconductor multilayer reflective film,
At least one Al _x Ga _{1 -x} As layer (x: 0 <x <
An oxidation step of forming a current confinement layer by oxidizing the Al _x Ga _{1 -x} As layer except for a part of the center from a side wall by heating in an oxygen atmosphere after the electrode forming step. It is characterized by including.

According to a third aspect of the present invention, on a semiconductor substrate:
A first conductive type lower semiconductor multilayer reflective film, a semiconductor active layer,
A semiconductor layer laminating step of sequentially laminating an upper semiconductor multilayer reflective film of the second conductivity type, selectively removing at least a portion of the upper semiconductor multilayer reflective film to form a semiconductor columnar region, and further in the vicinity thereof An etching step of selectively etching and removing the semiconductor active layer to expose the lower semiconductor multilayer reflective film, and a portion of the upper semiconductor multilayer reflective film near the semiconductor columnar region and further exposed to the vicinity thereof. An electrode forming step of forming first and second electrodes respectively so as to contact the lower semiconductor multilayer reflective film, and forming a first electrode on the surface of the lower semiconductor multilayer reflective film in an electrode formation region before forming the semiconductor active layer. The method is characterized by including an impurity introduction step of introducing a one-conductivity-type impurity at a high concentration to form a high-concentration impurity region.

Preferably, the upper or lower semiconductor multilayer reflective film contains at least one Al _x Ga _{1 -x} As layer (x: 0 <x <1), and is formed in an oxygen atmosphere after the electrode forming step. By heating, the Al _x Ga _1-x A
An oxidation step of oxidizing the s layer except for a part of the center from the side wall to form a current confinement layer is included.

Preferably, the active layer is formed by the oxidation step to define a current path above or below the active layer,
The high-concentration impurity region is extended to just below the semiconductor pillar so that the edge of the current constriction layer that defines the current path and the end of the high-concentration impurity region substantially coincide with each other. .

According to the present invention, since a high-concentration impurity region is formed in a region having a high contact resistance due to absorption of free carriers, a good ohmic contact can be obtained without deteriorating laser characteristics. It becomes possible.

Further, from the opening, a high concentration impurity region is formed.
It is configured to extend to a part of the central area, which is the light emitting area defined by the current confinement layer, just below the semiconductor pillar, so that a low-resistance area is formed near the area contributing to laser oscillation. Therefore, the resistance at the time of current injection is reduced, the threshold voltage is lowered, and the laser characteristics are significantly improved.

Furthermore, since the high-concentration impurity region has a high refractive index and a light confinement effect, it is possible to increase the luminous efficiency. Further, by forming a current confinement layer that defines a current path below the active layer, the current injection efficiency is further improved, and the threshold voltage is greatly improved.

Further, the high-concentration impurity region is extended to just below the semiconductor pillar so that the edge of the current constriction layer defining the current path substantially coincides with the end of the high-concentration impurity region. Carriers and light are efficiently guided, and the luminous efficiency is further improved.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a surface emitting semiconductor laser device according to a first embodiment of the present invention.

This surface-emitting type semiconductor laser device includes a p-type A-type semiconductor formed on a p-type gallium arsenide (GaAs) substrate 1.
1 _0.9 Ga _0.1 As / Al _0.3 Ga _0.7 As Lower semiconductor multilayer reflective film 2, lower spacer layer 4 made of undoped Al _0.6 Ga _0.4 As, and undoped Al _0.11 Ga _0.89 formed on lower spacer layer 4 A quantum well active layer 4 composed of a quantum well layer and an undoped Al _0.3 Ga _0.7 As barrier layer; an upper spacer layer 6 composed of undoped Al _0.6 Ga _0.4 As; an n-type AlAs layer 7 and a current confinement layer formed by oxidation thereof 8, and n-type Al _0.9 Ga _0.1 As /
Al _0.3 Ga _0.7 As upper semiconductor multilayer reflective film 9 and n-type Ga
An As protective layer 10 is sequentially laminated, and the upper semiconductor multilayer reflective film 9 and the n-type GaAs protective layer 10 are removed by etching except for the area above the light emitting region, thereby forming a columnar light control region. Then, the upper semiconductor multilayer reflection film 9
Is removed by etching from a part of the surface of the removal region to a depth reaching the p-type lower semiconductor multilayer reflective film 2, and the surface of the p-type lower semiconductor multilayer reflective film 2 has a carrier concentration of 1 × 10 ¹⁹ c.
A p-type impurity diffusion region 3 containing beryllium Be at a high concentration of m ^-3 is formed, and an ohmic contact with a p-side electrode 11 formed thereon is formed. As a result, the contact resistance is reduced to about one third of the conventional resistance.
Thus, the surface of the n-type upper semiconductor multilayer reflective film 9 and the p-type
P-side electrodes 11 and n made of Au / Ti are formed on the surface of p-type impurity diffusion region 3
The side electrode 12 is formed.

The lower semiconductor multilayer reflective film 2 is made of Al
It is formed by laminating a _0.9 Ga _0.1 As layer and an Al _0.7 Ga _0.3 As layer with a thickness of λ / (4n _r ) (λ: oscillation wavelength, n _r : refractive index) for about 40.5 periods. is there. The lower spacer layer 4 is made of undoped Al _0.6 Ga _0.4
The quantum well active layer 5 is composed of an undoped Al _0.11 Ga _0.89 quantum well layer (film thickness 8 nm ×
3) and undoped Al _{0. 3} Ga _0.7 As barrier layer (thickness 5
nm × 4), the upper spacer layer 6 is made of undoped Al _0.6 Ga _0.4 As, and the total thickness is an integral multiple of λ / n _r . The upper semiconductor multilayer reflection film 9, Al _0.9 Ga _0.1 As layer and the Al _{0 .7} Ga
_0.3 AsGaAs layer and λ / (4n _r )
(Λ: oscillation wavelength, n _r : refractive index) are formed by alternately laminating 30 periods. In order to prevent oxidation, the uppermost protective layer 10 was an n-type GaAs layer. Further, the n-type AlAs layer 7 has a λ / (4n _r ) protective layer 1.
0 is 3λ / (4n _r ). The number of periods of the upper semiconductor multilayer reflective film 9 is made smaller than the number of periods of the lower semiconductor multilayer reflective film 2 in order to extract outgoing light from the upper surface of the substrate with a difference in reflectance. The kind of the dopant is not limited to the one used here, and it is also possible to use silicon and selenium for n-type and beryllium for zinc or magnesium for p-type. The impurity diffusion region 3 increases the carrier concentration of the surface layer, changes the state to a state where electrical contact can be easily made, and causes a mixed crystal with the surrounding semiconductor layer. It also has the effect of increasing the energy band gap of the region compared to the active region,
The current confinement effect in the light emitting region is improved, and further, the refractive index is increased in the impurity diffusion region 3 and the light confinement is improved. The current flows through the quantum well active layer 5 between the n-side electrode 12 and the p-side electrode 11 formed on the n-type upper semiconductor multilayer reflective film 9 and the p-type impurity diffusion region 3.

In this manner, a laser beam having an oscillation wavelength λ = 780 nm can be extracted from the substrate surface.

According to this structure, the current path and the light confinement can be performed by a relatively easy process, so that the refraction index guided surface emitting laser device having good laser characteristics and high reproducibility can be realized. Can be provided.
In addition, even when the number of elements is large in a two-dimensional array, a high yield can be obtained.

Next, the manufacturing process of this surface emitting semiconductor laser device will be described. First, as shown in FIG. 2, a p-type A is deposited on a p-type gallium arsenide (GaAs) (100) substrate 1 by metal organic chemical vapor deposition (MOCVD).
l _0.9 Ga _0.1 As / Al _0.3 Ga _0.7 As Lower semiconductor multilayer reflective film 2, lower spacer layer 4 made of undoped Al _0.6 Ga _0.4 As, undoped Al _0.11 Ga _0.89 quantum well layer and undoped Al _0.3 Ga _0.7 A quantum well active layer 5 composed of an As barrier layer and undoped Al _0.6 Ga
_An upper spacer layer 6 made of _0.4 As, an n-type AlAs layer 7, and an n-type Al _0.9 Ga _0.1 As / Al _0.3 Ga _0.7
An As upper semiconductor multilayer reflective film 9 and a protective layer 10 made of an n-type GaAs layer are sequentially laminated. Then, the substrate is taken out of the growth chamber, a resist mask 13 is formed by photolithography as shown in FIG. 3, and the upper semiconductor multilayer reflective film 9 is selectively removed using a sulfuric acid-based etchant. This etching step was stopped at such a depth that the n-type AlAs layer 7 was not exposed. As a result, a semiconductor pillar was formed.

Then, as shown in FIG. 4, a resist mask 13 is formed by a photolithography technique.
Lower semiconductor multilayer reflective film 2 using sulfuric acid based etchant
Was etched to a depth at which. Thereby, a terrace for forming the n-side electrode was formed. further,
A p-type impurity was introduced outside the terrace by ion implantation. Here, beryllium ions were used as p-type impurities, and ion implantation was performed at a dose of 1 × 10 ¹⁹ cm ^{−3 and an} acceleration voltage of 1 keV. Thereby, the p-type impurity diffusion region 3
Was formed.

Next, the resist mask 13 is removed and 800
Activation annealing was performed at 10 ° C. for 10 minutes. This gives p
Carrier concentration of the impurity diffusion region 3 is approximately 1 × 10 ¹⁹ c
m ^-3 was confirmed.

Further, by photolithography and monochlorobenzene treatment, an overhang-shaped resist pattern 13 was formed as shown in FIG.

An Au / Ti film was formed thereon by the EB vapor deposition method, and the p-side electrode 11 and the n-side electrode 12 were formed by lifting off the resist and the Au / Ti on the resist. This was further annealed to alloy Au / Ti. This is exposed to a steam atmosphere, and n-type AlA
The s layer 7 was oxidized from the side to form a current confinement layer 8. Thus, the surface emitting semiconductor laser device according to the embodiment of the present invention shown in FIG. 1 is completed.

In the above embodiment, each semiconductor layer is formed by metal organic chemical vapor deposition. However, the present invention is not limited to this. For example, molecular beam epitaxy (MBE) may be used.

As a result of examining the contact resistance of the p-side electrode of this surface-emitting type semiconductor laser device, an ohmic contact was obtained instead of the conventional Schottky characteristic.
The contact resistance was also reduced to one third of the conventional one. The operation of the surface-emitting type semiconductor laser device manufactured as described above is as follows. Here, carriers are injected from the p-side electrode 11 into the lower semiconductor multilayer reflective film 2 and the quantum well active layer 5 via the p-type diffusion region 3, and current is supplied to the n-side electrode 12 via the upper semiconductor multilayer reflective film 9. Is flowing. Then, the carriers injected into the quantum well layer emit light by electron-hole recombination. The light is reflected by the upper and lower semiconductor multilayer reflection films, and laser oscillation occurs when the gain exceeds the loss. Laser light is emitted from the surface of the semiconductor pillar.

Next, a method of manufacturing a surface emitting semiconductor laser device according to a second embodiment of the present invention will be described with reference to FIGS. This method is characterized in that the method of forming the p-type impurity diffusion region is different from that of the first embodiment, and the p-type impurity diffusion region is formed by metal organic chemical vapor deposition (MOCVD).
Gallium arsenide (GaAs) (100) substrate 1
After the p-type _{Al 0.9 Ga 0.1 As / Al 0} .3 Ga 0.7 As lower semiconductor multilayer reflection film 2 is laminated, as shown in FIG. 6, a resist mask 1 by a photolithography technique
3 is formed, and using this as a mask by ion implantation,
A p-type impurity was introduced. Here, beryllium ions were used as p-type impurities, and ion implantation was performed at a dose of 1 × 10 ¹⁹ cm ^{−3 and an} acceleration voltage of 1 keV. Thus, a p-type impurity diffusion region 3 was formed.

Subsequently, after removing the resist mask 13,
Similarly, a lower spacer layer 4 made of undoped Al _0.6 Ga _0.4 As and an undoped Al _0.11 Ga _{0.89 are formed on the} upper layer by metal organic chemical vapor deposition (MOCVD).
A quantum well active layer 5 composed of a quantum well layer and an undoped Al _0.3 Ga _0.7 As barrier layer, and an undoped Al _0.6 G
a _0.4 As upper spacer layer 6 and n-type AlAs
Layer 7 and n-type _{Al 0 .9 Ga 0.1 As / Al} 0.3 Ga
_{A 0.7} As upper semiconductor multilayer reflective film 9 and a protective layer 10 made of an n-type GaAs layer are sequentially laminated (see FIG. 7). Then, the substrate is taken out of the growth chamber, and a resist mask 13 is formed by photolithography as shown in FIG.
Upper semiconductor multilayer reflection film 9 using a sulfuric acid-based etchant
Is selectively removed. This etching step is an n-type Al
It was stopped at a depth where the As layer 7 was not exposed. As a result, a semiconductor pillar was formed.

Further, as shown in FIG. 9, a resist mask 13 is formed by a photolithography technique.
Etching is performed using a sulfuric acid-based etchant to a depth where the p-type impurity diffusion region 3 is exposed. Thereby, a terrace for forming the n-side electrode was formed.

Further, an overhang-shaped resist pattern 13 was formed by photolithography and monochlorobenzene treatment as shown in FIG.

A Au / Ti film was formed thereon by the EB vapor deposition method, and the p-side electrode 11 and the n-side electrode 12 were formed by lifting off the resist and the Au / Ti on the resist. This was further annealed to alloy Au / Ti. This is exposed to a steam atmosphere, and n-type AlA
The s layer 7 was oxidized from the side to form a current confinement layer 8. Thus, the surface emitting semiconductor laser device according to the embodiment of the present invention shown in FIG. 1 is completed.

As a result of examining the contact resistance of the p-side electrode of this surface-emitting type semiconductor laser device, it was found that an ohmic contact was obtained instead of the conventional Schottky characteristic.
The contact resistance was also reduced to one third of the conventional one. In the first and second embodiments, the high-concentration impurity region 3 for the p-side electrode contact is formed only in the contact region and its vicinity, but extends to just below the light emitting region defined by the current confinement layer. You may form so that it may be. The high-concentration impurity region 3 has two functions such as low resistance and low contact resistance, while having a high refractive index and capable of increasing the light confinement effect. Next, as a third embodiment of the present invention, which is one example of this, a high-concentration impurity region 3 for a p-side electrode contact is provided.
A structure will be described below, which extends to the light emitting region defined by the current confinement layer 8 immediately below the semiconductor pillar as shown in FIG.

In this surface-emitting type semiconductor laser device, the high concentration impurity region 3 in the first embodiment of the present invention shown in FIG. 1 is formed only on the terrace for forming the p-side electrode 11. On the other hand, this surface-emitting type semiconductor laser device is different only in that the high-concentration impurity region 3 extends to the vicinity of the inner end of the current confinement layer 8, and the other structures are exactly the same.

Next, a method of manufacturing the surface emitting semiconductor laser device of the third embodiment will be described with reference to FIGS. First, metal organic chemical vapor deposition (MOCV
D) method, p-type gallium arsenide (GaAs) (10
0) p-type Al _0.9 Ga _0.1 As / Al _0.3
After the Ga _0.7 As lower semiconductor multilayer reflective film 2 is formed by lamination, as shown in FIG. 12, a resist mask 13 is formed immediately above a region corresponding to a light emitting region by photolithography.
Is formed, and using this as a mask, p
Type impurities were introduced. Here, as in the second embodiment, beryllium ions were used as p-type impurities, and ion implantation was performed at a dose of 1 × 10 ¹⁹ cm ^{−3 and an} acceleration voltage of 1 keV. Thus, a p-type impurity diffusion region 3 was formed.

Subsequently, after the resist mask 13 is removed,
Similarly, a lower spacer layer 4 made of undoped Al _0.6 Ga _0.4 As and an undoped Al _0.11 Ga _{0.89 are formed on the} upper layer by metal organic chemical vapor deposition (MOCVD).
A quantum well active layer 5 composed of a quantum well layer and an undoped Al _0.3 Ga _0.7 As barrier layer, and an undoped Al _0.6 G
a _0.4 As upper spacer layer 6 and n-type AlAs
Layer 7 and n-type _{Al 0 .9 Ga 0.1 As / Al} 0.3 Ga
_{A 0.7} As upper semiconductor multilayer reflective film 9 and a protective layer 10 made of an n-type GaAs layer are sequentially laminated (see FIG. 13). Then, the substrate is taken out of the growth chamber, a resist mask 13 is formed by photolithography as shown in FIG. 14, and the upper semiconductor multilayer reflective film 9 is selectively removed using a sulfuric acid-based etchant. This etching step was stopped at such a depth that the n-type AlAs layer 7 was not exposed. This allows
Semiconductor pillars were formed.

Further, as shown in FIG. 15, a resist mask 13 is formed by a photolithography technique, and is etched using a sulfuric acid-based etchant to a depth at which the p-type impurity diffusion region 3 is exposed. This gives n
Terraces for forming side electrodes were formed.

Further, by photolithography and monochlorobenzene treatment, an overhang-shaped resist pattern 13 having an opening formed in the electrode forming region was formed as shown in FIG.

An Au / Ti film was formed thereon by the EB vapor deposition method, and the resist and the Au / Ti on the resist were lifted off to form the p-side electrode 11 and the n-side electrode 12. This was further annealed to alloy Au / Ti. This is exposed to a steam atmosphere, and n-type AlA
The s layer 7 was oxidized from the side to form a current confinement layer 8. Thus, the surface emitting semiconductor laser device according to the embodiment of the present invention shown in FIG. 11 is completed.

As a result of examining the contact resistance of the p-side electrode of this surface-emitting type semiconductor laser device, the contact resistance was further reduced as compared with the second embodiment, and the luminous efficiency was improved. This is presumably because the high-concentration impurity region reduces the contact resistance and forms a high-refractive-index light-trapping region.

Next, a fourth embodiment of the present invention will be described. In this example, in addition to the structure of the surface emitting semiconductor laser device of the third embodiment, the edge of the high-concentration impurity region 3 extending to the vicinity of the light emitting region is also provided below the active layer 5. A feature is that a current constriction layer 8 is formed so as to match. This current confinement layer 8 is made of p-type Al
It is formed by selective oxidation from the side of the As layer 14.
The other structure is formed in exactly the same manner as in the third embodiment. Next, a method of manufacturing the surface emitting semiconductor laser device according to the fourth embodiment will be described with reference to FIGS. First, as shown in FIG. 12 in the third embodiment, metal organic chemical vapor deposition (MOC)
VD) method, p-type gallium arsenide (GaAs) (1
00) p-type Al _0.9 Ga _0.1 As / Al
After laminating the _0.3 Ga _0.7 As lower semiconductor multilayer reflective film 2, as shown in FIG. 18, a resist mask 13 is formed immediately above a region corresponding to a light emitting region by a photolithography technique.
Is formed, and using this as a mask, p
Type impurities were introduced. Here, as in the second embodiment, beryllium ions were used as p-type impurities, and ion implantation was performed at a dose of 1 × 10 ¹⁹ cm ^{−3 and an} acceleration voltage of 1 keV. Thus, a p-type impurity diffusion region 3 was formed.

Subsequently, after removing the resist mask 13,
Similarly, a lower spacer layer 4 made of undoped Al _0.6 Ga _0.4 As, a p-type AlAs layer 14 and an undoped Al _0.11 Ga _0.89 quantum well layer are formed on the upper layer by metal organic chemical vapor deposition (MOCVD). Undoped Al
_A quantum well active layer 5 comprising a _0.3 Ga _0.7 As barrier layer;
An upper spacer layer 6 made of undoped Al _0.6 Ga _0.4 As, an n-type AlAs layer 7, and an n-type Al _0.9 Ga
_0.1 As / Al _0.3 Ga _0.7 As upper semiconductor multilayer reflective film 9
And a protective layer 10 made of an n-type GaAs layer are sequentially laminated (see FIG. 19). Then, the substrate is taken out of the growth chamber, a resist mask 13 is formed by photolithography as shown in FIG. 20, and the upper semiconductor multilayer reflective film 9 is selectively removed using a sulfuric acid-based etchant. This etching step was stopped at such a depth that the n-type AlAs layer 7 was not exposed. As a result, a semiconductor pillar was formed.

Further, as shown in FIG. 21, a resist mask 13 is formed by a photolithography technique, and is etched using a sulfuric acid-based etchant to a depth at which the p-type impurity diffusion region 3 is exposed. As a result, a terrace for forming the n-side electrode was formed inside the etching region.

Further, by photolithography and monochlorobenzene treatment, an overhang-shaped resist pattern 13 having an opening formed in the electrode forming region was formed as shown in FIG.

An Au / Ti film was formed thereon by the EB vapor deposition method, and the p-side electrode 11 and the n-side electrode 12 were formed by lifting off the resist and the Au / Ti on the resist. This was further annealed to alloy Au / Ti. This is exposed to a steam atmosphere, and p-type AlA
The s layer 14 and the n-type AlAs layer 7 were oxidized from the side to form a current confinement layer 8. Thus, the surface-emitting type semiconductor laser device according to the embodiment of the present invention shown in FIG. 17 is completed.

In the surface-emitting type semiconductor laser device, in addition to the effect of the third embodiment, the current injection efficiency is improved by providing the current confinement layer below the active layer, and the laser characteristics are improved. .

Next, a fifth embodiment of the present invention will be described. In this example, in addition to the structure of the surface emitting semiconductor laser device of the first (and second) embodiment shown in FIG. 1, a light emitting region is also provided below the active layer 5 as shown in FIG. The current confining layer 8 is formed so as to substantially coincide with the end of the high-concentration impurity region 3 extending to the vicinity of. This current confinement layer 8 is formed of a p-type AlAs layer 14.
Is formed by selective oxidation from the side of. The other structure is formed in exactly the same manner as in the first embodiment.

Next, a method of manufacturing the surface emitting semiconductor laser device of the fifth embodiment will be described with reference to FIGS. First, in the second embodiment, FIG.
Metal-organic chemical vapor deposition (MOCVD)
P-type gallium arsenide (GaAs) (100)
On a substrate 1, a p-type Al _0.9 Ga _0.1 As / Al _0.3 G
After laminating a _0.7 As lower semiconductor multilayer reflective film 2,
As shown in FIG. 18, a resist mask 13 is formed in a region excluding an electrode formation region by a photolithography technique,
Using this as a mask, a p-type impurity was introduced by ion implantation. Here, as in the second embodiment, beryllium ions are used as p-type impurities, and the dose amount is 1 × 10 4.
Ion implantation was performed at an acceleration voltage of ¹⁹ cm ^{-3 and} 1 keV. Thus, a p-type impurity diffusion region 3 was formed.

Subsequently, after the resist mask 13 is removed,
Similarly, a lower spacer layer 4 made of undoped Al _0.6 Ga _0.4 As, a p-type AlAs layer 14 and an undoped Al _0.11 Ga _0.89 quantum well layer are formed on the upper layer by metal organic chemical vapor deposition (MOCVD). Undoped Al
_A quantum well active layer 5 comprising a _0.3 Ga _0.7 As barrier layer;
An upper spacer layer 6 made of undoped Al _0.6 Ga _0.4 As, an n-type AlAs layer 7, and an n-type Al _0.9 Ga
_0.1 As / Al _0.3 Ga _0.7 As upper semiconductor multilayer reflective film 9
And a protective layer 10 made of an n-type GaAs layer are sequentially laminated (see FIG. 25). Then, the substrate is taken out of the growth chamber, a resist mask 13 is formed by photolithography as shown in FIG. 26, and the upper semiconductor multilayer reflective film 9 is selectively removed using a sulfuric acid-based etchant. This etching step was stopped at such a depth that the n-type AlAs layer 7 was not exposed. As a result, a semiconductor pillar was formed.

Further, as shown in FIG. 27, a resist mask 13 is formed by a photolithography technique, and is etched using a sulfuric acid-based etchant to a depth at which the p-type impurity diffusion region 3 is exposed. As a result, a terrace for forming the n-side electrode was formed inside the etching region.

Further, as shown in FIG. 28, an overhang-shaped resist pattern 13 having an opening formed in the electrode forming region was formed by photolithography and monochlorobenzene treatment.

An Au / Ti film was formed thereon by EB vapor deposition, and the resist and the Au / Ti on the resist were lifted off to form the p-side electrode 11 and the n-side electrode 12. This was further annealed to alloy Au / Ti. This is exposed to a steam atmosphere, and p-type AlA
The s layer 14 and the n-type AlAs layer 7 were oxidized from the side to form a current confinement layer 8. Thus, the surface emitting semiconductor laser device according to the embodiment of the present invention shown in FIG. 23 is completed.

In the surface-emitting type semiconductor laser device, in addition to the effects of the first embodiment, the current injection efficiency is improved by providing the current confinement layer below the active layer, and the laser characteristics are improved. .

According to the structure of the embodiment described above, the n-side electrode 12 and the p-side electrode 11 can be formed simultaneously using the same material. This is advantageous when arranging a plurality of individual devices to form electrodes that can be accessed independently of each other, for example, when creating a matrix arrangement device. In this case, it is desirable to use a metal material having good bonding characteristics to both n and p. However, it goes without saying that the n-side electrode and the p-side electrode may be formed of different materials and using two photolithography processes.

Further, since the wiring can be performed only at the bottom of the semiconductor pillar, a step which causes a decrease in the yield of the element such as a step breakage in the case of performing photolithography in a stepped area is not required. Thus, a highly reliable device can be obtained.

In the above embodiment, the case where the MOCVD apparatus is used as the crystal growth apparatus has been described. However, the present invention is not limited to this. For example, a molecular beam epitaxy (MBE) apparatus, a liquid phase epitaxy (LPE) apparatus, etc. May be used.

Further, in the above-described embodiment, a GaAs / AlGaAs-based semiconductor is used as a material constituting the quantum well active layer. However, the present invention is not limited to this. For example, a GaAs / InGaAs-based semiconductor or a quantum well active layer may be used. I
It is also possible to use an nP / InGaAsP-based semiconductor.

As the electrode metal, not only Au / Ti but also Ti-based alloys such as Pt / Ti, and other Au-based alloys may be used as materials used in the compound semiconductor process. The conditions for ion implantation may be such that the accelerating voltage, impurity type, and dose are changed according to the electrode material and the like. As p-type impurities, in addition to Be, Mg, Z
You may use n, C, etc. Depending on the properties of the device, an n-type impurity may be introduced into the n-side instead of the p-side.

Needless to say, the present invention can be realized by other methods within a range satisfying the constitutional requirements of the present invention.

[0069]

As described above, according to the present invention, the p-side electrode can be brought into ohmic contact, and the contact resistance can be reduced while the p-side electrode and the n-side electrode are formed of the same material. It is possible to provide a surface-emitting type semiconductor laser device having excellent laser characteristics.

Further, since the electrodes are formed at the bottom of the semiconductor pillar and the p-side electrode and the n-side electrode can be formed of the same material, a highly reliable surface emitting semiconductor laser can be obtained. Can be. In particular, this structure is very effective for integration.

[Brief description of the drawings]

FIG. 1 is a diagram showing a surface emitting semiconductor laser device according to a first embodiment of the present invention;

FIG. 2 is a first manufacturing process diagram of the surface-emitting type semiconductor laser device.

FIG. 3 is a first manufacturing process diagram of the surface-emitting type semiconductor laser device;

FIG. 4 is a first manufacturing process diagram of the surface-emitting type semiconductor laser device;

FIG. 5 is a first manufacturing process diagram of the surface-emitting type semiconductor laser device.

FIG. 6 is a second manufacturing process diagram of the surface-emitting type semiconductor laser device.

FIG. 7 is a second other manufacturing process diagram of the surface-emitting type semiconductor laser device;

FIG. 8 is a second manufacturing process diagram of the surface-emitting type semiconductor laser device.

FIG. 9 is a second manufacturing process diagram of the surface-emitting type semiconductor laser device.

FIG. 10 is a second manufacturing process diagram of the surface-emitting type semiconductor laser device.

FIG. 11 is a view showing a surface-emitting type semiconductor laser device according to a third embodiment of the present invention;

FIG. 12 is a manufacturing process diagram of a surface-emitting type semiconductor laser device according to a third embodiment of the present invention;

FIG. 13 is a manufacturing process diagram of the surface-emitting type semiconductor laser device according to the third embodiment of the present invention.

FIG. 14 is a manufacturing process diagram of the surface emitting semiconductor laser device according to the third embodiment of the present invention;

FIG. 15 is a manufacturing process diagram of the surface emitting semiconductor laser device according to the third embodiment of the present invention;

FIG. 16 is a manufacturing process diagram of the surface-emitting type semiconductor laser device according to the third embodiment of the present invention;

FIG. 17 is a view showing a surface-emitting type semiconductor laser device according to a fourth embodiment of the present invention;

FIG. 18 is a manufacturing process diagram of the surface-emitting type semiconductor laser device according to the fourth embodiment of the present invention;

FIG. 19 is a manufacturing process diagram of the surface-emitting type semiconductor laser device according to the fourth embodiment of the present invention.

FIG. 20 is a manufacturing process diagram of the surface-emitting type semiconductor laser device according to the fourth embodiment of the present invention;

FIG. 21 is a manufacturing process diagram of the surface-emitting type semiconductor laser device according to the fourth embodiment of the present invention;

FIG. 22 is a manufacturing process diagram of the surface-emitting type semiconductor laser device according to the fourth embodiment of the present invention;

FIG. 23 is a view showing a surface emitting semiconductor laser device according to a fifth embodiment of the present invention;

FIG. 24 is a manufacturing process diagram of the surface emitting semiconductor laser device according to the fifth embodiment of the present invention;

FIG. 25 is a view showing a manufacturing process of a surface-emitting type semiconductor laser device according to a fifth embodiment of the present invention;

FIG. 26 is a manufacturing process diagram of the surface emitting semiconductor laser device according to the fifth embodiment of the present invention;

FIG. 27 is a manufacturing process diagram of the surface-emitting type semiconductor laser device according to the fifth embodiment of the present invention;

FIG. 28 is a view showing a manufacturing process of a surface-emitting type semiconductor laser device according to a fifth embodiment of the present invention;

FIG. 29 is a diagram showing a conventional surface-emitting type semiconductor laser device.

FIG. 30 is a manufacturing process diagram of a surface-emitting type semiconductor laser device according to a conventional example.

FIG. 31 is a manufacturing process diagram of a surface-emitting type semiconductor laser device according to a conventional example.

FIG. 32 is a view showing a manufacturing process of a surface-emitting type semiconductor laser device according to a conventional example.

FIG. 33 is a manufacturing process diagram of a surface-emitting type semiconductor laser device according to a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 p-type gallium arsenide (GaAs) substrate 2 p-type lower semiconductor multilayer reflective film 3 p-type high-concentration impurity region 4 p-type lower spacer layer 5 quantum well active layer 6 n-type upper spacer layer 7 n-type AlAs layer 8 current Narrowing layer 9 Upper semiconductor multilayer reflective film 10 Protective film 11 p-side electrode 12 n-side electrode 13 resist 14 p-type AlAs layer

Claims (9)

[Claims] 1. A semiconductor columnar structure in which at least a lower semiconductor multilayer reflection film, an active layer, and an upper semiconductor multilayer reflection film are sequentially stacked on a substrate, and the upper multilayer reflection film is selectively formed on a light emitting region. Forming a first electrode adjacent to the semiconductor columnar structure so as to contact the upper multilayer reflective film, and further forming an opening so as to expose the lower semiconductor multilayer reflective film; A surface emitting semiconductor laser device in which a second electrode is formed in a region exposed inside the semiconductor laser device, wherein a portion not forming an optical waveguide including a lower semiconductor multilayer reflective film exposed in the opening is the same as the lower semiconductor multilayer reflective film. A surface-emitting type semiconductor laser device wherein a high-concentration impurity region containing a high-conductivity-type impurity is formed. 2. The surface-emitting type semiconductor laser device according to claim 1, wherein said lower semiconductor multilayer reflection film is formed of a p-type semiconductor layer. 3. The high-concentration impurity region is configured to extend from the opening to a position immediately below a semiconductor pillar and to a vicinity of a partial central region serving as a light-emitting region defined by a current confinement layer. The surface-emitting type semiconductor laser device according to claim 1, wherein: 4. A current confinement layer defining a current path is formed above or below the active layer, and an edge of the current confinement layer defining a current path substantially coincides with an end of the high-concentration impurity region. 4. The surface-emitting type semiconductor laser device according to claim 3, wherein: 5. A semiconductor layer laminating step of sequentially forming a first conductive type lower semiconductor multilayer reflective film, a semiconductor active layer, and a second conductive type upper semiconductor multilayer reflective film on a semiconductor substrate; An etching step of selectively removing a portion of the upper semiconductor multilayer reflection film to form a semiconductor columnar region and selectively removing the semiconductor active layer in the vicinity thereof by selective etching to expose the lower semiconductor multilayer reflection film; Forming first and second electrodes so as to contact a part of the upper semiconductor multilayer reflective film in the vicinity of the semiconductor columnar region and the lower semiconductor multilayer reflective film exposed in the vicinity thereof, respectively; After the formation of the semiconductor active layer, prior to the electrode forming step, a first semiconductor multilayer reflection film on the surface of the lower semiconductor multilayer reflective film in the etching removal region is provided. Method for producing a conductive type impurities are introduced at a high concentration, the surface-emitting type semiconductor laser device which comprises an impurity introduction step for forming a high-concentration impurity regions. 6. The upper or lower semiconductor multilayer reflective film includes at least one Al _x Ga _{1 -x} As layer (x: 0 <x
An oxidation step of forming a current confinement layer by heating the substrate in an oxygen atmosphere after the electrode forming step to oxidize the Al _x Ga _{1 -x} As layer except for a part of the center from a side wall. 6. The method for manufacturing a surface-emitting type semiconductor laser device according to claim 5, comprising: 7. A semiconductor layer laminating step of sequentially laminating a first conductive type lower semiconductor multilayer reflective film, a semiconductor active layer, and a second conductive type upper semiconductor multilayer reflective film on a semiconductor substrate; An etching step of selectively removing a portion of the upper semiconductor multilayer reflection film to form a semiconductor columnar region and selectively removing the semiconductor active layer in the vicinity thereof by selective etching to expose the lower semiconductor multilayer reflection film; Forming first and second electrodes so as to contact a part of the upper semiconductor multilayer reflective film in the vicinity of the semiconductor columnar region and the lower semiconductor multilayer reflective film exposed in the vicinity thereof, respectively; Prior to the formation of the semiconductor active layer, a first conductivity type impurity is introduced at a high concentration on the surface of the lower semiconductor multilayer reflective film in the electrode formation region, A method for manufacturing a surface-emitting type semiconductor laser device, comprising an impurity introducing step of forming a concentration impurity region. 8. The upper or lower semiconductor multilayer reflective film has at least one Al _x Ga _{1 -x} As layer (x: 0 <x
An oxidation step of forming a current confinement layer by oxidizing the Al _x Ga _{1 -x} As layer except for a part of a center from a side wall by heating in an oxygen atmosphere after the electrode forming step. The method for manufacturing a surface-emitting type semiconductor laser device according to claim 7, comprising: 9. An edge of the current constriction layer formed by the oxidation step to define a current path above or below the active layer and defining a current path, and an end of the high concentration impurity region. 9. The method according to claim 8, wherein the high-concentration impurity region is extended to just below the semiconductor pillar so as to substantially coincide with each other.