JP2946852B2 - Semiconductor light emitting device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device and a method for manufacturing the same. More specifically, the present invention relates to a semiconductor light emitting device such as a surface emitting type (top emission type) semiconductor diode that emits light from a surface, and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIGS. 5 and 6 are a sectional view and a plan view showing the structure of a conventional light emitting diode.

This is a light emitting diode 51 having a double hetero structure, in which an n-Al substrate is provided on an n-GaAs substrate 52.
GaAs lower cladding layer 53, p-GaAs active layer 5
4. After sequentially growing the p-AlGaAs upper cladding layer 55, a radial dot electrode 56 is provided on the upper surface of the upper cladding layer 55, and a back electrode 57 is provided on the lower surface of the substrate 52.

In order to increase the output of the light emitting diode 51 having the above-described structure, it is necessary to move the active layer 5 from the dot electrode 56.
It is necessary to inject a current uniformly into the entirety of the active layer 4, to generate light in the entire active layer 54, and to efficiently emit the light generated in the active layer 54 to the outside without being blocked by the dot electrode 56. .

For this reason, in the conventional light emitting diode 51, the dot electrodes 56 are formed radially as shown in FIG. 6 so that the current is uniformly injected into the active layer 54.

[0006]

However, when the dot electrode is made radial, the area of the electrode increases, so that there is a problem that the amount of light that can be extracted to the outside is reduced due to the shadow of the dot electrode on the active layer. .

In order to make the active layer less likely to be shadowed by the dot electrode, the distance between the active layer and the dot electrode may be increased. For this purpose, it is necessary to increase the thickness of the upper cladding layer. , It takes a lot of man-hours.

Further, of the light traveling from the active layer to the interface between the upper cladding layer and the outside, the light that forms an angle greater than the critical angle with the interface is totally reflected and cannot be extracted outside. As a result, it has become more difficult to improve the light output of the light emitting diode.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object to emit light by uniformly injecting current from the electrode to the entire active layer. Another object of the present invention is to reduce the decrease in the amount of light.

[0010]

A semiconductor device according to claim 1 is provided.
The optical element is a semiconductor light emitting element in which light generated in the active layer is emitted from the light extraction layer to the outside. In the semiconductor light emitting element, almost the entire surface of the light extraction layer is highly doped with impurities of the same conductivity type as the light extraction layer. Forming high-concentration semiconductor regions
An electrode is provided on a part of the surface of the light extraction layer .
The same impurity as that of the high-concentration semiconductor region is added to at least a region on the surface of the light extraction layer where no electrode is provided.
It is characterized in that a non-reflective coating film which is included in the concentration and satisfies the non-reflective condition for light having the emission wavelength is formed .

According to a second aspect of the present invention, in the method of manufacturing a semiconductor light emitting device, a diffusing agent layer containing an impurity of the same conductivity type as the light extraction layer and satisfying a non-reflection condition with respect to light having an emission wavelength is provided on substantially the entire surface of the light extraction layer. Then, the impurity is diffused from the diffusing agent layer to the light extraction layer to form a high-concentration semiconductor region, whereby the semiconductor light emitting device is manufactured.

[0012]

According to the semiconductor light emitting device of the present invention, the current can be diffused wider than the electrode area in the high-concentration semiconductor region where the impurity is doped at a high concentration, and the current can be widely and uniformly injected into the active layer. Light can be emitted from the entire active layer.

Therefore, it is not necessary to form the electrodes radially as in the prior art, the area of the electrodes can be reduced, and the light emitted from the active layer can be efficiently emitted without being shadowed by the electrodes.

In addition, since a non-reflection coating film is formed on the light extraction layer, light emitted from the active layer is emitted to the outside with high efficiency without being reflected inside by the light extraction layer, and the semiconductor light emission The output of the element can be increased.

Further, in the semiconductor light emitting device and the method of manufacturing the same according to the present invention, a non-reflective coating film is formed using a diffusing agent layer for forming a high concentration semiconductor region by diffusion. Therefore, the manufacturing process of the semiconductor light emitting device can be simplified, and the cost of the semiconductor light emitting device can be reduced.

Further, since it is not necessary to make the upper clad layer unnecessarily thick unlike the conventional case, the production becomes simpler.

[0017]

1 and 2 are a sectional view and a plan view showing a surface emitting type light emitting diode 1 according to one embodiment of the present invention.
(A)-(e) is sectional drawing which shows the manufacturing method.

Hereinafter, the light emitting diode 1 will be described according to a manufacturing order. First, for example, MOCVD (Metal-
The Organic CVD) or the like, an upper clad having a composition of the lower cladding layer 3 having the composition of n-Al _0.3 Ga _0.7 As on the n-GaAs substrate 2, p-GaAs active layer _{4, p-Al 0.3 Ga 0.7} As Layer 5 is sequentially grown (FIG. 3)
(A)).

Next, a coatable diffusing agent (OCD) composed of, for example, SiO ₂ and Zn (diffusion element) is applied on the upper cladding layer 5 by a spinner (not shown). Then, a diffusing agent layer 6 serving as a Zn diffusion source is formed (FIG. 3B). The thickness of the diffusing agent layer 6 is controlled to be λ / 4n (non-reflection condition), where λ is the emission center wavelength of the light emitting diode and n is the refractive index of the diffusing agent layer 6. For example, in this embodiment, lamp annealing is finally performed at 800 ° C. for 10 minutes.
Assuming that the refractive index of the diffusing agent layer 6 is n = 1.44 and the emission wavelength is λ = 880 nm, the coating thickness of the diffusing agent layer 6 needs to be 1530 °.

FIG. 4 shows various characteristics in the case where a coatable diffusing agent (OCD) comprising SiO ₂ and a diffusing element is applied by a spinner to form a diffusing agent layer 6 and baked at 800 ° C. for 10 minutes after the application. FIG. 4 is a graph showing the relationship between the rotation speed of a spinner and the film thickness of a diffusing agent layer with respect to the SiO ₂ concentration of FIG. Therefore, a diffusing agent (OC) having a SiO ₂ concentration of, for example, 5.9%
Assuming that D) was used, in order to finally obtain a film thickness of 1530 ° under a lamp annealing condition at 800 ° C. for 10 minutes, according to FIG. 4, the spinner rotation speed was 1800 rpm.
And it is sufficient.

Next, the diffusing agent layer 6 is baked at 300 ° C. for 60 minutes.

Further, the diffusing agent layer 6 is heated at 800 ° C. for 10 minutes by, for example, lamp annealing to diffuse Zn into the upper cladding layer 5. Thereby, a part of the p-AlGaAs upper cladding layer 5 becomes a high-concentration p-type layer, and p ⁺ −
An AlGaAs high-concentration semiconductor region 7 is formed (FIG. 3).
(C)).

Thereafter, an AZ resist 8 is formed on the diffusing agent layer 6.
Then, the center portion is opened in a circular shape with a diameter of 100 μm using a normal photolithography technique, and the diffusion agent layer 6 in a portion exposed from the opening 9 of the AZ resist 8 is further etched using hydrofluoric acid (HF). Etching removal (Fig. 3
(D)).

Next, an electrode material of Cu / Au is vapor-deposited on the upper surface, and the AZ resist 8 is removed to form a circular dot electrode 10 of Cu / Au at the opening of the diffusing agent layer 6 by a lift-off method.

Finally, Au is formed on the lower surface of the n-GaAs substrate 2.
The back electrode 11 made of GeNi is formed (FIG. 3).
(E)).

In the light emitting diode 1 manufactured as described above, when a voltage is applied between the dot electrode 10 and the back surface electrode 11, the current i injected from the dot electrode 10 becomes as shown in FIG. In the p ⁺ -AlGaAs high-concentration semiconductor region 7, the active layer 4 spreads to the periphery, and
To be uniformly injected. Therefore, the active layer 4 emits light not only in the area directly below the dot electrode 10 but also in almost the entire area. For this reason, the dot electrode 10 can be made relatively small, and the ratio of the light emitted from the active layer 4 to the shadow of the dot electrode 10 decreases, and the light output emitted from the upper surface increases. Further, the upper clad layer 5 does not need to be formed to a thickness larger than necessary.

Moreover, since the diffusing agent layer 6 left on the upper surface (light extraction surface) of the light emitting diode 1 satisfies the above-described non-reflection condition, it functions as a non-reflection coating film for light generated in the active layer 4. In addition, the light emitted from the active layer 4 and the reflected light cancel each other out, and there is no light reflected on the upper surface of the light emitting diode 1. In particular, total reflection at the interface between the upper cladding layer 5 and the outside can be eliminated. That is,
All the light generated in the active layer 4 is emitted to the outside without being reflected on the upper surface, the intensity of the emitted light from the light emitting diode 1 increases, and the output becomes high.

In the above embodiment, AlGaAs was used.
Although the semiconductor light emitting device having the s / GaAs double hetero structure has been described, the present invention can be applied to semiconductor light emitting devices having other structures, and may be applied to a single-hetero structure or a homo structure. Can be. Also, I
Similar effects can be obtained with other materials such as nGaAsP / InP. Further, the conductivity types of p and n may be opposite to those in the above-described embodiment. In this case, the diffusion source may be doped with a donor impurity.

[0029]

According to the present invention, the current can be diffused more widely than the electrode area in the high-concentration semiconductor region.
Light can be emitted from the entire active layer, and the area of the electrode can be reduced, so that light emitted from the active layer does not easily become a shadow of the electrode.

Further, the light emitted from the active layer is emitted to the outside with high efficiency without being reflected inside by the light extraction layer, and the output of the semiconductor light emitting device can be increased.

Further, since the anti-reflection coating film is formed by using the diffusing agent layer for forming the high-concentration semiconductor region by diffusion, the manufacturing process of the semiconductor light emitting device can be simplified. The cost of the light emitting element can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a plan view of the same.

FIGS. 3 (a), (b), (c), (d), and (e) are cross-sectional views showing the same manufacturing method.

FIG. 4 is a diagram showing the relationship between the rotation speed of a spinner and the thickness of a diffusing agent layer for various SiO ₂ concentrations.

FIG. 5 is a sectional view of a conventional example.

FIG. 6 is a plan view of the same.

[Explanation of symbols]

 Reference Signs List 4 active layer 5 upper cladding layer 6 diffusing agent layer (anti-reflection coating film) 7 high-concentration semiconductor region 10 dot electrode

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-34984 (JP, A) JP-A-51-57298 (JP, A) JP-A-3-84969 (JP, A) JP-A 64-64 18279 (JP, A) JP-A-2-174272 (JP, A) JP-A-4-100279 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 33/00

Claims (2)

(57) [Claims] 1. A semiconductor light emitting device in which light generated in an active layer is emitted from a light extraction layer to the outside,
High-concentration semiconductor region substantially the entire surface is doped the same conductivity type impurity and the light extraction layer to the high concentration of the light extraction layer
An electrode is provided on a part of the surface of this light extraction layer.
The same impurity as the high-concentration semiconductor region in at least a region on the surface of the light extraction layer where no electrode is provided.
A semiconductor light emitting device comprising a non-reflective coating film which is contained at a high concentration and satisfies a condition for non-reflection of light having an emission wavelength. 2. The method for manufacturing a semiconductor light emitting device according to claim 1, wherein the light diffusing agent layer includes an impurity of the same conductivity type as the light extraction layer and satisfies a condition of non-reflection for light of an emission wavelength. A method for manufacturing a semiconductor light emitting device, comprising: forming a high-concentration semiconductor region by applying the impurity from the diffusing agent layer to the light extraction layer after applying the coating to almost the entire surface of the extraction layer.