JP3463788B2 - Method for manufacturing semiconductor light emitting device - 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 used for a light source of a display device and a method of manufacturing the same.
In particular, it relates to a high brightness GaP light emitting diode and a method for manufacturing the same.

[0002]

2. Description of the Related Art In general, a semiconductor light emitting element used in a display device or the like consumes less power as the luminance is higher, so that a semiconductor light emitting element having high luminance is desired. In particular, a semiconductor light emitting device with higher brightness is desired because it is easily affected by ambient light when used outdoors.

As an example of this type of semiconductor light emitting device, G
There is an aP light emitting diode. This GaP light emitting diode includes red light emitting diode and green light emitting diode, but a green light emitting diode made of N-doped GaP is mainly used for outdoor displays requiring high brightness.

FIG. 9A shows a sectional structure of a conventional GaP light emitting diode. This GaP light emitting diode has a first n-type GaP layer 32, a second n-type GaP layer 33 and a p-type G formed on an n-type GaP substrate 31 by epitaxial growth.
A structure in which the aP layer 34 is sequentially stacked, that is, n-n-n-
It has a p structure. A light extraction side p-type electrode 35 is formed on the upper surface of the p-type GaP layer 34, and an n-type electrode 30 is formed on the lower surface of the n-type GaP substrate 31. In this GaP light emitting diode, the second n-type Ga forming a pn junction is used.
The P layer 33 has a low carrier concentration.

In this GaP light emitting diode, the recombination process of light emission is an indirect transition. Therefore, in order to increase the brightness of this GaP light emitting diode, it is important to improve its crystal quality, especially, the crystallinity in the vicinity of the pn junction.

Further, since the GaP light emitting diode has a small amount of light absorption of the crystal with respect to the emission wavelength and emits light from the entire crystal to the outside, it is possible to improve the light extraction efficiency in order to increase the brightness. is important.

[0007]

Therefore, the Ga of the conventional example is
In the P light emitting diode, the carrier concentration is kept low in order to improve the crystal quality. However, in this case, the spread of the current with respect to the crystal size becomes poor, and in an extreme case, only the portion directly below the light extraction side p-type electrode 35 emits light. That is, as shown in FIG. 9B, the distribution of the emission intensity Ib in the light emitting portion near the pn junction is concentrated immediately below the light extraction side p-type electrode 35.
There arises a problem that the light extraction efficiency becomes low.

As a method for solving this problem, for example,
Japanese Unexamined Patent Publication No. 6-97498 describes that a current blocking layer is formed in an epitaxial layer structure of a light emitting diode having a heterojunction to improve current spreading.

Therefore, it is conceivable to provide the GaP light emitting diode with the current blocking layer as in the case of the light emitting diode having this heterojunction.

However, when the above method is applied to a GaP light emitting diode, there are the following problems.

(1) There is a problem that the manufacturing efficiency is lowered and the manufacturing cost of the GaP light emitting diode is increased.

The reason is that the crystal growth of the GaP light emitting diode is performed by the liquid phase epitaxial growth method.
This is because growth can be performed in a solution, but in the case of providing a current blocking layer, a plurality of solutions are required, and the manufacturing process is complicated, the number of processes is increased, and the manufacturing time is lengthened.

The conventional GaP light emitting diode shown in FIG. 9 has an n-n-n-p structure. General Ga
In the case of a P light emitting diode, an n type is widely used as a single crystal substrate used for its epitaxial growth. For this reason,
When the current blocking layer is provided before the pn junction formation epitaxial growth, the current blocking layer is p-type. Therefore, the number of solutions required for epitaxial growth is the minimum of two solutions.

However, in this case, since the diffusion length of electrons which are minority carriers in the current blocking layer is long, it is necessary to grow the current blocking layer to a large thickness, and the current blocking layer is etched in the next step. It is disadvantageous in doing.

On the other hand, when the layer thickness is reduced, it is necessary to increase the p-type carrier concentration. Therefore, when Zn is used as the dopant, another problem arises in that the current blocking layer impairs its function because Zn diffuses due to heat during epitaxial growth for forming the next pn junction.

To solve this problem, the pn junction is first formed on the n-type GaP substrate, the n-type current blocking layer is epitaxially grown, the etching process is performed, and then the p-type GaP layer is further epitaxially grown. A method can be considered. However, according to this method, an n-type current blocking layer can be formed, but at least three types of solutions are required,
There is a problem that the manufacturing efficiency is lowered and the manufacturing cost of the GaP light emitting diode is increased.

(2) When patterning the electrode on the light extraction side,
There is a problem in performing alignment between the current blocking layer and the light extraction side electrode.

Generally, when a current blocking layer is provided in a light emitting diode having a heterojunction, an infrared ray is applied from the back side of the patterning surface to align the current blocking layer and the light extraction side electrode when patterning the light extraction side electrode. Take the method of transmitting. In the case of a light emitting diode having a heterojunction, an optical path difference occurs in transmitted light due to a difference in refractive index between the current blocking layer and the epitaxial layer covering the current blocking layer, so that the pattern of the current blocking layer can be observed. Therefore, this is used for alignment.

However, since the GaP light emitting diode has a homojunction, there is no difference in refractive index between the current blocking layer and the epitaxial layer covering it, and the above alignment method cannot be used.

Therefore, for example, a method may be considered in which an orientation flat is provided on the wafer before forming the current blocking layer and the patterning direction is determined in advance.

However, in the case of this method,
Since a number of processes are performed from the formation of the current blocking layer to the formation of the electrode on the light extraction side, there is a possibility that the direction of repatterning may not be known due to wafer cracking. In addition, since the epitaxial growth is performed after forming the current blocking layer, the shape of the orientation flat portion provided on the wafer may be slightly changed, which may cause pattern shift.

The present invention solves the above-mentioned problems of the prior art, and is a semiconductor in which the crystallinity of the light emitting portion near the pn junction is good, the light extraction efficiency is high, the brightness is high, and the characteristics are stable. An object is to provide a light emitting device and a method for manufacturing the same.

Another object of the present invention is to provide a method for manufacturing a semiconductor light emitting device, which can accurately align the current blocking layer and the light extraction side electrode when patterning the light extraction side electrode.

Still another object of the present invention is to provide a method for manufacturing a semiconductor light emitting device which can reduce the kinds of solutions required for liquid phase epitaxial growth, improve the manufacturing efficiency and reduce the manufacturing cost.

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

According to a method of manufacturing a semiconductor light emitting device of the present invention, a first conductivity type GaP layer, a first second conductivity type GaP layer and a second conductivity type GaP layer are formed on a first conductivity type GaP substrate. Of the first conductivity type GaP layer are successively subjected to liquid phase epitaxial growth with one solution, and an etching process is performed so that the central portion of the second first conductivity type GaP layer remains.
A step of forming a first conductivity type current blocking layer, and a step of forming the first second
A regrowth step of liquid phase epitaxially growing a second second conductivity type GaP layer on the conductivity type GaP layer and the current blocking layer, and forming the current blocking layer on the second second conductivity type GaP layer. An electrode forming step of forming a light-extraction-side second-conductivity-type electrode in a portion corresponding to the region is included, whereby the above object is achieved.

Preferably, in the growth step, the first and second conductivity type GaP layers and the second and first conductivity type GP layers are used.
The aP layer is formed with a background carrier concentration in liquid phase epitaxial growth by supplying NH ₃ gas.

Further, preferably, the growth temperature in the regrowth step is in the range of 800 ° C to 900 ° C.

Preferably, Zn is used as a dopant in the regrowth step.

Further, according to the method of manufacturing a semiconductor light emitting device of the present invention, when the current blocking layer and the second GaP layer of the second conductivity type are formed, the impurity concentration of the current blocking layer and the second conductivity of the second conductivity type are formed. A difference between the impurity concentration of the type GaP layer and a difference between the refractive index of the current blocking layer and the refractive index of the second second conductivity type GaP layer; When patterning the second conductivity type electrode, a step of irradiating light from the outside of the substrate on the side opposite to the light extraction side second conductivity type electrode, and transmission of the current blocking layer and the second second conductivity type GaP layer The method includes the step of aligning the current blocking layer and the light-extraction-side second-conductivity-type electrode by utilizing the difference in light intensity, whereby the above object is achieved.

The operation of the present invention will be described below with reference to FIG.

According to the above structure, the first-conductivity-type current blocking layer 4 is formed so as to overlap the substantially central portion of the first second-conductivity-type GaP layer 3, and the second second-conductivity-type GaP is formed. A second conductivity type electrode 6 on the light extraction side is formed in a portion corresponding to the formation region of the current blocking layer 4 with the layer 5 interposed therebetween. Moreover, the current blocking layer 4 and the first second conductivity type GaP layer 3 have a low carrier concentration.

Current blocking layer 4 and first and second conductivity type GaP
Since the layer 3 has a low carrier concentration, the crystal quality is improved and the light transmittance is improved. Further, by providing the current blocking layer 4, the spread of the current is improved and the light extraction efficiency is improved. Therefore, it is possible to increase the brightness of the semiconductor light emitting device.

Further, the current blocking layer 4 and the first and second conductivity type G
The carrier concentration in the joint surface with the aP layer 3 is minimized, and the carrier concentrations in the current blocking layer 4 and the first second conductivity type GaP layer 3 increase from the joint surface in the layer thickness direction of each layer. The structure. According to the experimental results of the inventors, it was confirmed that the crystal quality was further improved and the light transmittance was further improved.

Specifically, these carrier concentrations are shown in FIG.
It is desirable to set it in the range of 5 × 10 ¹⁵ cm ^{−3 to} 20 × 10 ¹⁵ cm ^{−3 shown} in FIG.

On the other hand, when the carrier concentration is low, the diffusion length of electrons which become minority carriers in the current blocking layer 4 becomes long, but since the epitaxial growth is performed by the liquid phase epitaxial growth method, the current blocking layer 4 can be made thick. Therefore, the function of the current blocking layer 4 does not deteriorate. Specifically, it is desirable that the current blocking layer 4 has a layer thickness of 5 μm or more.

As a result, the current spreads around the light-extraction-side second-conductivity-type electrode 6 in the semiconductor light-emitting element, so that the distribution of the emission intensity is not concentrated immediately below the second-conductivity-type electrode 6 and the light-emission is prevented. The distribution of the intensity Ia is as shown in FIG. That is, it is possible to improve the light extraction efficiency and the luminous intensity by causing the peripheral portion of the second conductivity type electrode 6 that has not conventionally emitted light to emit light. Therefore, it is possible to increase the brightness of the semiconductor light emitting device.

In addition, if the current blocking layer 4 is set to be transparent with respect to the emission wavelength, the amount of light attenuation can be reduced,
Since it is possible to further improve the luminous intensity, it is effective in increasing the brightness of the semiconductor light emitting element.

By setting the segregation coefficient of impurities serving as carriers in the current blocking layer 4 to be smaller than the segregation coefficient of impurities serving as carriers in the first second conductivity type GaP layer 3, the current blocking layer 4 becomes the first. It becomes conductive type.

Therefore, two kinds of solutions are required for the liquid phase epitaxial growth, the manufacturing process is simplified, the number of processes is reduced, and the manufacturing time is shortened. Therefore, it is possible to improve the manufacturing efficiency and reduce the manufacturing cost of the semiconductor light emitting device.

In the growth step, when NH ₃ gas is supplied, the NH ₃ gas reacts with Si in the GaP solution,
The carrier concentration decreases rapidly, and carbon C, which is a p-type impurity supplied from the carbon epitaxial growth boat, and S, which is an n-type impurity supplied from the n-type GaP substrate 1, remain more than the Si concentration in the GaP solution. The impurity concentration becomes dominant. Therefore, the polarity of epitaxial growth is dominated by the background carrier concentration. Therefore, as the wafer is gradually cooled, the first N-doped p-type GaP layer 3 is formed by C or the like, which is a p-type impurity having a segregation coefficient larger than 1, due to the difference in segregation coefficient of residual impurities. S, which is an n-type impurity having a segregation coefficient smaller than 1,
As a result, the second N-doped n-type GaP layer 4 ′ is formed.

In the regrowth step, the growth temperature is set to 80.
When the temperature is in the range of 0 ° C. to 900 ° C., the growth rate in the liquid phase epitaxial growth becomes small, so that holes and the like are frequently generated in the second second conductivity type GaP layer 5, and the crystal quality deteriorates. Therefore, a difference can be provided between the light absorption coefficient of the current blocking layer 4 and the light absorption coefficient of the second GaP layer 5 of the second conductivity type.

In the re-growth step, Zn is used as a dopant, and the light absorption coefficient of the current blocking layer 4 and the second absorption coefficient are increased by utilizing the relationship that the absorption amount of light increases as the doping amount of Zn increases. A difference can be provided between the two-conduction type GaP layer 5 and the light absorption coefficient.

Moreover, when Zn is used as the dopant, since the segregation coefficient of Zn is approximately 1, a uniform concentration profile can be obtained as shown in FIG. 5, so that the characteristics of the semiconductor light emitting device can be stabilized. It will be possible. still,
If the segregation coefficient is approximately 1, the same effect can be obtained by using an element other than Zn, such as Mg.

However, if the doping amount of Zn is too large, the light extraction efficiency is lowered. Therefore, the carrier concentration of the second GaP layer 5 of the second conductivity type is 1 × 10 ¹⁸ cm ^{−3 to} 5 ×.
It is desirable to set it in the range of 10 ¹⁸ cm ⁻³ . When the carrier concentration range is set, the growth temperature may be set to any range.

Further, since there is an inverse correlation between the light absorption coefficient and the refractive index, the light absorption coefficient of the current blocking layer 4 and the light absorption coefficient of the second second conductivity type GaP layer 5 are as described above. The difference between the refractive index of the current blocking layer 4 and the refractive index of the second second-conductivity-type GaP layer 5 is caused by providing the difference between the current blocking layer 4 and the current blocking layer 4. Therefore, in the electrode forming step, when light is irradiated from the outside of the substrate on the side opposite to the light extraction side second conductivity type electrode 6, the current blocking layer 4 and the second second layer are caused due to the difference in the refractive index. Conductivity type Ga
Since an intensity difference occurs in the transmitted light from the P layer 5, it is possible to distinguish the current blocking layer and the second second conductivity type GaP layer by using the transmission image obtained thereby. Therefore, even in a semiconductor light emitting device having a homojunction, the second light extraction side second
When patterning the conductivity type electrode 6, alignment with the current blocking layer 4 can be performed accurately.

[0055]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1A shows a sectional structure of the GaP light emitting diode of the present invention. This GaP light emitting diode is
A first n-type GaP layer 2 and a first p-type GaP layer 3 are sequentially stacked on a Ga-type GaP substrate (wafer) 1 by liquid phase epitaxial growth.
The n-type current blocking layer 4 made of aP is superposed, and the first p-type GaP layer 3 and the n-type current blocking layer 4 are formed so as to cover the n-type current blocking layer 4.
Structure in which the second p-type GaP layer 5 is laminated on the type current blocking layer 4, that is, nn in which the n-type current blocking layer 4 is provided inside
-P-p structure.

On the upper surface of the second p-type GaP layer 5, n
The light extraction side p is formed in a portion corresponding to the formation region of the mold current blocking layer 4.
The mold electrode 6 is formed, and the n-type electrode 7 is formed on the lower surface of the n-type GaP substrate 1. In this GaP light emitting diode, the first p-type GaP layer 3 and the n-type current blocking layer 4 have a low carrier concentration.

A method of manufacturing the GaP light emitting diode of the present invention will be described based on the manufacturing process chart of FIG. 2 and the temperature program of liquid phase epitaxial growth of FIGS. 3 and 4.

The wafer is set in the growth apparatus, hydrogen gas is used as a carrier gas, and the flow rate is 4 L (liter) / m.
in, and the GaP solution is dipped on the n-type GaP substrate 1 at a temperature of 1000 ° C. (see FIG. 2A and FIG. 3A).

Next, the wafer is slowly cooled at a rate of 0.5 ° C./min.
At 900 ° C. At this time, Si is doped and the first n-type GaP layer 2 is formed on the n-type GaP substrate 1.
Are formed (see FIG. 2B and FIG. 3B).

Next, NH ₃ gas is supplied together with hydrogen gas at 900 ° C. At this time, 900 ° C. is held for about 30 minutes (see FIG. 3c). This is the time for reacting the NH ₃ gas and the GaP solution. As a result, NH ₃ gas and G
Si in the aP solution reacts, the carrier concentration is rapidly reduced, and it is supplied from the carbon C or n-type GaP substrate 1, which is a p-type impurity supplied from the carbon epitaxial growth boat, compared to the Si concentration in the GaP solution. The concentration of residual impurities such as S, which is an n-type impurity, becomes dominant.

Next, the wafer is cooled to 850 ° C. at a slow cooling rate of 0.
Cool at 5 ° C / min. At this time, the residual impurity concentration is dominant, and the polarity of epitaxial growth is dominated by the background carrier concentration. Therefore, due to the difference in the segregation coefficient of the residual impurities, first, the segregation coefficient is 1
The first N-doped p-type GaP layer 3 is formed by C, which is a larger p-type impurity, and then the second N-doped n-type Ga is formed by S, which is an n-type impurity having a segregation coefficient smaller than 1.
A P layer 4'is formed (see FIG. 2B, FIG. 3d).
The carrier concentration of each formed layer is 5 × 10 ¹⁵ cm ⁻³ or more.
It is in the range of 20 × 10 ¹⁵ cm ⁻³ . With this, the first growth is completed, and the wafer is taken out from the growth apparatus.

Next, an SiO ₂ film is formed on the surface of the wafer, and patterning of about 80 μmφ to 120 μmφ is performed.
Second N-doped n-type GaP layer 4'is formed by etching.
The peripheral portion of the is removed to form the n-type current blocking layer 4 (see FIG. 2).
(See (C)). The SiO ₂ film is removed and light etching is performed again. After that, the wafer is set in the growth apparatus again, and the second epitaxial growth is performed.

FIG. 4 shows a temperature program for the second liquid phase epitaxial growth.

As with the first time, hydrogen gas was used as the carrier gas, and the carrier gas was supplied at a flow rate of 4 L (liter) / min, and the GaP solution was immersed on the wafer at a temperature of 900 ° C. (see FIG. 4e).

Next, the wafer is slowly cooled at a rate of 0.5 ° C./min.
To cool to 850 ° C. At this time, Zn is doped to form the second p-type GaP layer 5 (FIG. 2).
(D), see FIG. 4f). The carrier concentration of the second p-type GaP layer 5 is 7 × 10 ¹⁷ cm ^{−3 to} 20 × 10 ¹⁷ cm.
The range is ^-3 . This completes the second growth.

When the second epitaxial growth is carried out at a temperature higher than the above, the carrier concentration of the second p-type GaP layer 5 formed is 1 × 10 ¹⁸ cm ⁻³ or more.
It may be in the range of 5 × 10 ¹⁸ cm ⁻³ .

The thickness of each epitaxial layer is 40 μm for the first n-type GaP layer 2 and 20 μm for the first p-type GaP layer 3.
m, n-type current blocking layer 4 is 5 μm, second p-type GaP layer 5
Is 10 μm.

FIG. 5 shows the result of measuring the carrier concentration just below the p-type electrode 6 on the light extraction side by the Schottky method.
Here, the vertical axis represents the impurity concentration and the horizontal axis represents the epitaxial growth direction. The carrier concentration of each epitaxial layer is
The first n-type GaP layer 2 is 2 × 10 ¹⁷ cm ⁻³ , and the first p-type GaP layer 3 is 0.5 × 10 ¹⁶ cm ⁻³ to 2 × 10 ¹⁶ c.
m ⁻³ , n-type current blocking layer 4 is 0.5 × 10 ¹⁶ cm ^{−3 to} 3 ×
10 ¹⁶ cm ⁻³ , the second p-type GaP layer 5 is 2 × 10 ¹⁸ cm
^-3 .

As shown in FIG. 5, the carrier concentration at the junction between the n-type current blocking layer 4 and the first p-type GaP layer 3 is minimized, and the n-type current blocking layer 4 and the first There is such a relationship that the carrier concentration of the p-type GaP layer 3 increases from the junction surface in the layer thickness direction of each layer.

By setting the segregation coefficient of impurities serving as carriers in the current blocking layer 4 to be smaller than the segregation coefficient of impurities serving as carriers in the first p-type GaP layer 3, the current blocking layer 4 becomes n-type. .

When Zn is used as the dopant for the second p-type GaP layer 5, since the segregation coefficient of Zn is about 1, a uniform concentration profile is obtained as shown in FIG. The characteristics of the device can be stabilized.

However, if the doping amount of Zn is too large, the light extraction efficiency is lowered. Therefore, the carrier concentration of the second second conductivity type GaP layer 5 is 1 × 10 ¹⁸ cm ^{−3 to} 5 ×.
It is desirable to set it in the range of 10 ¹⁸ cm ⁻³ . When the carrier concentration range is set, the growth temperature may be set to any range.

Next, a p-type electrode 6 on the light extraction side was formed in accordance with the current blocking layer 4 of this substrate and divided into 0.30 mm apertures, and the luminous intensity of the GaP light emitting diode was measured. As a result, the luminous intensity of the conventional GaP light emitting diode is 100 (light emitting color: yellowish green, light emitting wavelength λp: 565
(around nm), the GaP light emitting diode of the present invention obtained a luminous intensity of 140. This is because the distribution of the emission intensity Ib of the conventional GaP light emitting diode is concentrated immediately below the light extraction side p-type electrode 35 as shown in FIG. 9 (B), whereas in the GaP light emitting diode of the present invention, By spreading the current around the light extraction side p-type electrode 6 in the light emitting diode, the distribution of the emission intensity Ia becomes as shown in FIG. 1 (B), and the light extraction side p-type electrode 6 that has not conventionally emitted light is shown. This is because the effect of improving the luminous intensity was obtained by emitting light in the peripheral portion of.

Next, in the electrode forming step, the light extraction side p
A method of performing alignment with the n-type current blocking layer 4 when patterning the mold electrode 6 will be described with reference to FIGS.

This method is performed using the alignment apparatus shown in FIG. Wafer 1 taken out from the growth apparatus
2 is placed on the stage 11 of the alignment apparatus. The alignment light source 10 is provided below the stage 11.
Is provided, and a CCD camera 14 is provided above the wafer 12. The stage 11 is provided with an opening 16 at a portion through which the light from the alignment light source 10 passes. Also, on the side of the CCD camera 14,
An exposure light source 15 is provided.

Next, the alignment process will be described with reference to FIGS.

First, the epitaxially grown wafer 1
2 is lapped from the substrate side until the thickness of the wafer 12 becomes 280 μm, and further polished,
The surface of No. 2 is mirror-finished (step S1 in FIG. 8).

Next, an n-type electrode material is vapor-deposited on the surface of the mirror-finished wafer 12 to form an n-type electrode. At this time, in order to form the p-type electrode 6 on the light extraction side later, the n-type electrode is not formed on a part (R region) of the wafer edge (step S2 in FIG. 8).

Next, a p-type electrode material is vapor-deposited on the surface of the epitaxial growth layer of the wafer 12 to form the p-type electrode 6 on the light extraction side. At this time, similarly to the above, the p-type electrode 6 is not formed on a part (R region) of the wafer edge (step S2 in FIG. 8).

Next, a procedure for performing alignment with the n-type current blocking layer 4 when patterning the p-type electrode 6 on the light extraction side will be described.

A resist is applied to the upper surface of the wafer 12 placed on the stage 11 (step S3 in FIG. 8).

Mask pattern M of the p-side photomask 13
Has the same size as the shape of the n-type current blocking layer 4 or slightly larger than it.

Light from the alignment light source 10, for example, infrared rays L1 is radiated from the opening 16 of the stage to the back surface side of the wafer 12, and the infrared rays L1 are emitted from a part (R region) of the wafer edge where the previous electrode is not formed. Through. At this time, C
When the transmitted light L2 is observed by the CD camera 14, FIG.
, The n-type current blocking layer 4 and the second p-type GaP layer 5 are
At the interface with and, the contour P composed of a ring-shaped dark portion can be confirmed by the difference in brightness of transmitted light.

In order to provide the difference in the refractive index, in the second growth step, for example, Zn is used as the dopant.
By using the relationship that the absorption amount of light increases as the doping amount of Zn increases, the difference between the light absorption coefficient of the current blocking layer and the light absorption coefficient of the second second-conductivity-type GaP layer is determined. Set up.
Since there is an inverse correlation between the light absorption coefficient and the refractive index,
A difference in refractive index occurs between the n-type current blocking layer 4 and the second p-type GaP layer 5.

As another method, in the second growth step, the growth temperature in the range of 800 ° C. to 900 ° C. is set to reduce the growth rate in the liquid phase epitaxial growth, and the second second conductivity type GaP is used. It is also possible to provide a difference between the light absorption coefficient of the current blocking layer and the light absorption coefficient of the second second-conductivity-type GaP layer by reducing the crystal quality by generating a large number of holes or the like in the layer.

Using the R region, the transmission image N and the mask pattern M of the photomask 13 are aligned (step S4 in FIG. 8).

With the wafer 12 placed on the stage 11 and the photomask 13 aligned,
The stage 11 is moved to the exposure light source 15 side, and exposure is performed by the exposure light source 15 to form a pattern of the light extraction side p-type electrode 6 (step S4 in FIG. 8).

After etching the electrode material, the resist is peeled off and alloyed to complete the formation of the light extraction side p-type electrode 6 (steps S5 to S7 in FIG. 8).

Through the above steps, a GaP light emitting diode having the structure shown in FIG. 1A is manufactured.

The GaP described in the above embodiment is used.
The conductivity type of each semiconductor layer and electrode forming the light emitting diode may be reversed between the p type and the n type.

[0092]

As described above, according to the semiconductor light emitting device of the present invention, the current blocking layer and the first and second conductivity type Ga are provided.
Since the P layer has a low carrier concentration, the crystal quality is improved and the light transmittance is improved. Further, by providing the current blocking layer, the spread of the current is improved and the light extraction efficiency is improved. Therefore, it is possible to increase the brightness of the semiconductor light emitting device.

In particular, according to the semiconductor light emitting device of the second aspect, the carrier concentration at the junction surface between the current blocking layer and the first second conductivity type GaP layer is minimized, and the current blocking layer and the first blocking layer are formed. Since the carrier concentration of the first GaP layer of the second conductivity type increases from the bonding surface in the layer thickness direction of each layer, the crystal quality can be further improved and the light transmittance can be further improved.

In particular, according to the semiconductor light emitting device of the fifth aspect, since the current blocking layer is set to be transparent with respect to the emission wavelength, the luminous intensity can be further improved and the semiconductor light emitting device can be further improved. It is effective in achieving higher brightness.

In particular, according to the semiconductor light emitting device of the sixth aspect, the carrier concentrations of the current blocking layer and the first second conductivity type GaP layer are 5 × 10 ¹⁵ cm ^{−3 to} 20 × 10 ¹⁵ cm ^−3.
Since the range is set to, the light transmittance can be further improved.

In particular, according to the semiconductor light emitting element of the seventh aspect, since the layer thickness of the current blocking layer is 5 μm or more,
It is possible to prevent deterioration of the function of the current blocking layer.

Further, according to the semiconductor light emitting device of the eighth aspect, the carrier concentration of the second GaP layer of the second conductivity type is in the range of 1 × 10 ¹⁸ cm ^{−3 to} 5 × 10 ¹⁸ cm ^−3. Therefore, it is possible to prevent the light extraction efficiency from decreasing. Moreover, in this case, the growth temperature may be set to any range.

In particular, according to the semiconductor light emitting device of the third aspect, the segregation coefficient of the impurity which becomes the carrier in the current blocking layer is smaller than the segregation coefficient of the impurity which becomes the carrier in the first second conductivity type GaP layer. Therefore, the current blocking layer can be of the first conductivity type.

According to the method of manufacturing a semiconductor light emitting device according to the tenth aspect of the present invention, two kinds of solutions are required for the liquid phase epitaxial growth, which improves the manufacturing efficiency and reduces the manufacturing cost of the semiconductor light emitting device. be able to.

According to the method for manufacturing a semiconductor light emitting device according to the eleventh aspect, in particular, in the growing step, NH ₃
Since the liquid phase epitaxial growth is performed by supplying the gas, the first second conductivity type GaP layer and the second first conductivity type GaP layer can be formed with the background carrier concentration.

Further, according to the method for manufacturing a semiconductor light emitting device according to the twelfth aspect, since the growth temperature is set in the range of 800 ° C. to 900 ° C. in the re-growth step, the growth rate in liquid phase epitaxial growth is reduced. Then, a large number of holes and the like are generated in the second second conductivity type GaP layer to lower the crystal quality, so that the light absorption coefficient of the current blocking layer and the light absorption coefficient of the second second conductivity type GaP layer are reduced. There can be a difference between the two.

According to the method for manufacturing a semiconductor light emitting device according to the thirteenth aspect, since Zn is used as the dopant in the re-growth step, the light absorption coefficient of the current blocking layer is changed by changing the doping amount of Zn. And a light absorption coefficient of the second GaP layer of the second conductivity type can be provided with a difference. Moreover, since a uniform concentration profile can be obtained,
The characteristics of the semiconductor light emitting device can be stabilized.

According to the method for manufacturing a semiconductor light emitting device according to claim 14, particularly, at the time of patterning the light-extraction side second conductivity type electrode, the current blocking layer and the second second conductivity caused by the difference in the refractive index. The current blocking layer and the second GaP layer of the second conductivity type are distinguished from each other by utilizing the intensity difference in the transmitted light from the GaP layer of the second conductivity type.
Therefore, even in a semiconductor light emitting device having a homojunction, the current blocking layer and the light extraction side electrode can be accurately aligned.

[Brief description of drawings]

FIG. 1 is a sectional structural view (A) of a semiconductor light emitting device of the present invention,
FIG. 3 is a diagram showing a light emission intensity distribution (B) in a light emitting portion near the pn junction.

FIG. 2 is a diagram showing a manufacturing process of the semiconductor light emitting device of the present invention.

FIG. 3 is a diagram showing a first liquid phase epitaxial growth temperature program of the semiconductor light emitting device of the present invention.

FIG. 4 is a diagram showing a second liquid phase epitaxial growth temperature program for the semiconductor light emitting device of the present invention.

FIG. 5 is a diagram showing a carrier concentration profile immediately below a p-type electrode of the semiconductor light emitting device of the present invention.

FIG. 6 is a diagram illustrating a method of aligning a current blocking layer and a light extraction side electrode during electrode patterning in the electrode forming step of the semiconductor light emitting device of the present invention.

FIG. 7 is a diagram showing how the contour of the current blocking layer can be observed as a transmission image when infrared rays are transmitted from the back side of the electrode patterning surface in the electrode forming step of the semiconductor light emitting device of the present invention.

FIG. 8 is a diagram showing a procedure for performing alignment between the current blocking layer and the light extraction side electrode during electrode patterning in the electrode forming step of the semiconductor light emitting device of the present invention.

FIG. 9 is a diagram showing a cross-sectional structural view (A) of a conventional semiconductor light emitting device and a light emission intensity distribution (B) in a light emitting portion near the pn junction.

[Explanation of symbols]

1 n-type GaP single crystal 2 First n-type GaP layer 3 First p-type GaP layer 4'second n-type GaP layer 4 n-type current blocking layer 5 Second p-type GaP layer 6 p-type electrode 7 n-type electrode 10 Alignment light source 11 stages 12 wafers 13 Photomask 14 CCD camera 15 Light source for exposure 16 openings

Continuation of front page (56) Reference JP-A-6-97498 (JP, A) JP-A-4-212479 (JP, A) JP-A-4-229665 (JP, A) JP-A-6-29570 (JP , A) JP-A-6-196753 (JP, A) JP-A-55-63889 (JP, A) JP-A-48-88874 (JP, A) JP-A-7-326792 (JP, A) JP-A-7-326792 6-342935 (JP, A) JP 56-32779 (JP, A) JP 9-293896 (JP, A) JP 55-75277 (JP, A) JP 2-288373 (JP, A) A) JP-A-52-116072 (JP, A) JP-A-54-162494 (JP, A) JP-A-52-6094 (JP, A) JP-A-54-133093 (JP, A) JP-A-6 -120561 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 33/00 H01S 5/00-5/50

Claims (5)

(57) [Claims] 1. A first conductivity type GaP layer, a first second conductivity type GaP layer, and a second first conductivity type GaP layer are successively formed on a first conductivity type GaP substrate by one solution. And a growth step of performing liquid phase epitaxial growth, a step of performing an etching process so that the central portion of the second first-conductivity-type GaP layer remains, and forming a first-conductivity-type current blocking layer; A regrowth step of liquid-phase epitaxially growing a second second-conductivity GaP layer on the second-conductivity-type GaP layer and the current-blocking layer; and a step of forming the current-blocking layer on the second second-conductivity-type GaP layer. An electrode forming step of forming a light-extraction-side second-conductivity-type electrode in a portion corresponding to a formation region. 2. In the growing step, the first second
A conductive GaP layer and the second first conductive GaP layer,
2. The method for manufacturing a semiconductor light emitting device according to claim 1 , wherein an NH ₃ gas is supplied to form the semiconductor light emitting device at a background carrier concentration in liquid phase epitaxial growth. 3. The growth temperature in the regrowth step is set to 80.
The method for manufacturing a semiconductor light emitting device according to claim 1 or 2 , wherein the temperature is in the range of 0 ° C to 900 ° C. 4. The method for manufacturing a semiconductor light emitting device according to claim 1 , wherein Zn is used as a dopant in the regrowth step. 5. A second second conductor so as to cover the current blocking layer.
And a second GaP layer of the second conductivity type.
A portion corresponding to the formation region of the current blocking layer with the aP layer interposed therebetween.
The second extraction electrode on the light extraction side formed in the half
A method of manufacturing a conductive light emitting device, the current blocking layer and in forming the second second-conductivity-type GaP layer, a second impurity concentration and the second of the current blocking layer
A step of providing a difference between the impurity concentration of the conductivity type GaP layer and a difference between the refractive index of the current blocking layer and the refractive index of the second second conductivity type GaP layer; and the light extraction side. When patterning the second conductivity type electrode, a step of irradiating light from the outside of the substrate on the side opposite to the light extraction side second conductivity type electrode, the current blocking layer and the second second conductivity type GaP layer A method of manufacturing a semiconductor light emitting device, comprising the step of aligning the current blocking layer and the light-extraction-side second-conductivity-type electrode by utilizing a difference in intensity of transmitted light.