JP2546153B2 - Surface emitting device and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface emitting device which improves thermal characteristics by reducing device resistance and stabilizes a single transverse mode, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In order to apply the parallelism and spatial propagation properties of light to information processing, it is desirable to integrate elements two-dimensionally in the plane direction. High-density integration of such devices requires improvement of thermal characteristics of individual devices and stabilization of a single transverse mode. In order to realize the above, a surface emitting device, which has been reduced in resistance by constructing a two-step mesa structure, has been used up to now.
Photonics Technology Letters (P
photonics Technology Lette
rs) Vol. 5, p. 136, reported by Numai et al., and the buried structure of AlGaAs semiconductor layer was adopted, whereby current confinement and carrier confinement were carried out by using an in situ dry etching process. There is also an example. As this document 1993
Photonics Technology Letters (Ph
otonics Technology Letter
s) There is a paper by Kent D. Choquette et al., Volume 5, page 284.

[0003]

However, in the above report, in the first example, the injection resistance does not pass through the upper multilayer reflective film and the element resistance is reduced by the resistance of the upper multilayer reflective film, but the contact resistance is reduced. Has not been achieved,
Even if this contact layer is doped with high-concentration impurities, the high-concentration doped layer is simultaneously formed in the resonator, which causes disadvantages such as increased light absorption. In addition, stabilization of the single transverse mode is also caused. Therefore, there is a problem that it is necessary to reduce the element size, and accordingly, critical fine processing is required. Also, in the second example, the element resistance was not reduced at all, and there was a problem in improving the temperature characteristics of the element.

Therefore, in the present invention, an element indispensable for high-density integration such as reduction of element resistance including contact resistance and stabilization of a single transverse mode without leaving damage to the surface emitting element itself produced. The purpose is to realize.

[0005]

[Means for Solving the Problems] The means provided by the present invention for solving the above-mentioned problems include a step of forming a first multilayer reflective film on a semiconductor substrate, and an intermediate layer including an active layer thereon. A step of forming a second multilayer reflective film thereon, a step of removing at least a part of the second multilayer reflective film formed above, and a semiconductor pillar remaining after the removal. A surface comprising a light emitting portion, a step of forming a highly doped semiconductor layer by regrowth on both sides thereof as contact layers, and a step of forming a high resistance layer by proton injection on both sides of the active layer thereafter. It is a manufacturing method of a light emitting element.

Alternatively, a step of forming a first multilayer reflective film on a semiconductor substrate, a step of forming an intermediate layer including an active layer thereon, and a step of forming a second multilayer reflective film thereon. , A step of removing at least a part of the intermediate layer including the second multilayer reflective film and the active layer formed above, and the semiconductor pillar remaining after the removal is used as a light emitting portion, and the high resistance semiconductor layer is used as the active layer. A surface emitting device comprising a step of growing a crystal aside and a step of forming a highly-doped semiconductor layer on a side surface of an upper multilayer reflective film portion formed of the multilayer reflective film by crystal growth by a diagonally incident molecular beam. Is a manufacturing method.

Alternatively, the surface emitting element is manufactured by each of the above manufacturing methods.

[0008]

According to the present invention, since the regrowth method is used for forming the contact layer and the semiconductor layer used for burying, there is an advantage that no passivation by a dielectric film or the like is necessary. In addition, since the heavily doped semiconductor layer is used as the contact layer and the current injection path bypasses the upper multilayer film reflection mirror portion, the temperature characteristic of the element can be remarkably improved with the reduction of the element resistance. . In addition, the upper multilayer film reflecting mirror of the device has a buried structure, so that stabilization of a single transverse mode can be achieved at the same time. Further, the manufacturing method according to the fourth aspect has an advantage that the element is not damaged at all.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a sectional view of a surface emitting device shown for explaining an embodiment of the present invention. FIG. 2 is a diagram for explaining the manufacturing process. First, n-type GaAs
An n-type AlAs layer and an n-type GaAs layer are formed on the substrate 1 to have a thickness of λ / 4n (λ is the oscillation wavelength and n is the refractive index of the medium). After that, the above steps are repeated and the n-type semiconductor multilayer film reflecting mirror 2 is formed by stacking the layers for about 20 cycles. Next, n-type Al _x Ga _{1 -x} As (x = 0.3) is formed as an n-type cladding layer 3 on the n-type semiconductor multilayer film reflecting mirror 2.
.About.0.7) layer is formed to a thickness of about 50 nm to 1 .mu.m. On the n-type cladding layer 3, an active layer 4 of In _y Ga _{1 -y} A
s (y = 0.05 to 0.5) is formed to a thickness of about 10 nm to 30 nm. On the active layer 4, p-type Al _z Ga ₁ -z As (z = 0.3-0.
7) Form a layer of about 50 nm to 1 μm. On the p-type cladding layer 5, p-type AlAs and p-type GaAs layers are respectively formed to a thickness of λ / 4n (n is the refractive index of the medium) as in the case of the n-type semiconductor multilayer film reflecting mirror. By repeating the above, about 10 to 20 cycles are laminated. Thereby, the p-type semiconductor multilayer film reflecting mirror 6 is formed.

The wafer of FIG. 2 (a) obtained as described above is subjected to etching as shown in FIG. 2 (b) using, for example, SiO ₂ 7 as a mask, and the p-type semiconductor is left with the semiconductor pillar to be the light emitting portion. At least a part of the multilayer-film reflective mirror 6 is removed. In the removed portion, a highly doped semiconductor layer 8 is formed as a contact layer by regrowth so that the p-type semiconductor multilayer film reflecting mirror 6 is embedded as shown in FIG. 2C. After that, the unnecessary polycrystalline (poly) semiconductor layer 10 formed on the SiO ₂ 7 is removed by lift-off using buffered hydrofluoric acid. In order to carry out this lift-off efficiently, it is desirable to use an etching technique that allows undercutting during etching. Finally, protons (for example, H ⁺ ) are applied to the active layer 4 for current narrowing to the active layer.
2 (d) to form the proton injection region 9 to obtain the surface emitting device according to the present invention.

If the number of cycles of the p-type semiconductor multilayer film reflecting mirror 6 is sufficiently large (for example, 20 cycles or more), the side surface of the p-type semiconductor multilayer film reflecting mirror 6 is masked with a resist agent after the etching is completed. SiO ₂ may be removed by buffered hydrofluoric acid, and then a step of forming a contact layer by regrowth may be performed. Further, the multilayer film reflecting mirror is not limited to the semiconductor.

Similarly, FIG. 3 shows another embodiment according to the present invention. FIG. 4 is a diagram for explaining the manufacturing process. The process up to the first wafer formation is the same as in the case of the embodiment based on FIG. 1 described above. After that, as shown in FIG. 4B, etching is performed using SiO ₂ as a mask,
At least a part of the intermediate layer including the p-type semiconductor multilayer film reflecting mirror 16 and the active layer 14 is removed. Thereafter, after removing SiO ₂ , as shown in FIG. 4C, a high resistance layer 19 such as non-doped A is formed so as to fill at least both sides of the active layer.
lGaAs is formed by regrowth. Then, FIG. 4 (d)
The heavily doped semiconductor layer 18 is, for example, 1 × 10
It is formed of Be-GaAs with a doping concentration of ²⁰ cm ⁻³ . At this time, by performing crystal growth using obliquely incident molecular beams, the embedding up to the p-type semiconductor multilayer film reflecting mirror 16 can be completed.

Here, at the same time as the embodiment according to FIG.
The removal order of ₂ has a degree of freedom depending on the number of cycles of the multilayer film reflecting mirror, and the multilayer reflecting mirror is not limited to the semiconductor. Also, FIG.
The manufacturing method by is greatly affected by the depth of implantation,
Since it does not require the step of proton injection that makes the proton passage region a high resistance region, it is excellent in that there is no need to control the damage to the element, especially the heavily doped semiconductor layer, and the depth control. Furthermore, by using a material having a high thermal conductivity coefficient for the high resistance layer and the heavily doped semiconductor layer, the heat generated near the active layer can be efficiently removed,
It is also excellent in that it is possible to prevent thermal interference between adjacent elements at the time of high-density integration.

In the above embodiment, the device is a vertical cavity surface emitting laser, but the present invention is not limited to this, and the present invention can be applied to a pnpn surface emitting device.

[0015]

As described above, according to the present invention, it is possible to manufacture a surface emitting device which realizes reduction of device resistance and stabilization of a single transverse mode. As a result, the temperature characteristics of the device can be improved, stable light output can be realized, and high-density two-dimensional integration of the surface emitting device can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the present invention.

FIG. 2 is a cross-sectional view showing the steps of a manufacturing method according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining the present invention.

FIG. 4 is a cross-sectional view showing a step of another manufacturing method of the present invention.

[Explanation of symbols]

1 Semiconductor Substrate 2 n-type Semiconductor Multilayer Reflector 3 n-type Cladding Layer 4 Active Layer 5 p-type Cladding Layer 6 p-type Semiconductor Multilayer Reflector 7 SiO ₂ 8 Highly Doped Semiconductor 9 Proton Injection Region 10 Poly Semiconductor 11 Semiconductor Substrate 12 n-type semiconductor multilayer mirror 13 n-type cladding layer 14 active layer 15 p-type cladding layer 16 p-type semiconductor multilayer mirror 17 SiO ₂ 18 heavily doped semiconductor 19 high resistance layer 20 poly semiconductor

Continuation of front page (56) Reference JP-A-4-275485 (JP, A) JP-A-63-205979 (JP, A) JP-A-61-271886 (JP, A)

Claims (5)

(57) [Claims] 1. A semiconductor substrate, a first multilayer reflective film formed on the semiconductor substrate, an intermediate layer including an active layer formed on the first multilayer reflective film, and an intermediate layer of the intermediate layer. A second multilayer reflective film formed on the above, an opening from which at least a part of the second multilayer reflective film is removed, a semiconductor pillar to be a light emitting portion surrounded by the opening, and formed in the opening 2. A surface emitting device comprising: a contact layer containing a high concentration impurity as described above; and a high resistance layer in which protons are injected into the opening so as to reach at least the active layer. 2. A step of forming a first multilayer reflective film on a semiconductor substrate, a step of forming an intermediate layer including an active layer thereon, and a step of forming a second multilayer reflective film thereon. A step of removing at least a part of the second multilayer reflection film, and the semiconductor pillar remaining after the removal is used as a light emitting portion, and both sides of the semiconductor pillar are used as contact layers to re-grow a highly doped semiconductor layer. And a step of forming a high resistance layer on both sides of the active layer by injecting protons thereafter. 3. A semiconductor substrate, a first multilayer reflective film formed on the semiconductor substrate, an intermediate layer including an active layer formed on the first multilayer reflective film, and an intermediate layer of the intermediate layer. The second multilayer reflective film formed above, the opening removed to at least a part of the intermediate layer including the second multilayer reflective film and the active layer, and the semiconductor pillar to be a light emitting part surrounded by the opening A surface emitting device comprising: a high resistance layer formed around the active layer formed in the opening; and a high concentration impurity semiconductor layer formed on the high resistance layer. 4. A step of forming a first multilayer reflective film on a semiconductor substrate, a step of forming an intermediate layer including an active layer thereon, and a step of forming a second multilayer reflective film thereon. A step of removing at least a part of the intermediate layer including the second multilayer reflection film and the active layer, and a semiconductor pillar remaining after the removal is used as a light emitting portion, and a high resistance semiconductor layer is crystal-grown on both sides of the active layer. And a step of forming a highly-doped semiconductor layer on the side surface of the upper multilayer reflective film portion constituted by the multilayer reflective film by crystal growth by obliquely incident molecular beams. Device manufacturing method. 5. using a mask in the process the removal of the second multilayer reflective film or the second multilayer reflection film and the intermediate layer, after the high concentration impurity semiconductor layer is formed, is removed by the lift-off of polycrystalline semiconductor on the unnecessary mask 3. The method according to claim 2, wherein
Alternatively, the method for manufacturing the surface emitting device according to the item 4.