JP2008159628A - Semiconductor light-emitting element and manufacturing method of semiconductor light-emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting element having the high flexibility in selecting a material applicable to a window layer and suppressing its manufacturing cost, and also to provide a manufacturing method of the semiconductor light-emitting element. <P>SOLUTION: The semiconductor light-emitting element 1 is provided with a window layer 2 and a semiconductor layer 3. The semiconductor layer 3 has a structure in which an n-type cladding layer 4, a first light-emitting layer 5, a second light-emitting layer 6, a p-type clad layer 7, and a reflection layer 8 are sequentially laminated from the window layer 2 side. The window layer 2 is made of an insulative glass having a thickness of several μm-several hundreds μm and transmitting an infrared ray. The window layer 2 is pasted on the n-type clad layer 4 by thermo-compression bonding. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor light emitting device capable of emitting infrared light and a method for manufacturing the semiconductor light emitting device.

  Conventionally, a semiconductor light emitting element capable of emitting infrared rays used for IrDA optical communication and the like and a manufacturing method thereof are known.

  For example, as a semiconductor light emitting device capable of emitting infrared light, a light emitting layer capable of emitting infrared light grown on a growth substrate, a window layer provided on the infrared irradiation side of the light emitting layer, and an upper surface of the window layer. An electrode provided with an electrode provided on a portion is known. In such a semiconductor light emitting device, the distance between the light emitting layer and the surface of the window layer is increased by forming the window layer thick (for example, several tens of μm or more).

  Thereby, the incident angle of infrared rays at the interface between the surface of the window layer and the outside can be reduced, and total reflection of infrared rays can be suppressed. As a result, the intensity of infrared rays irradiated to the outside is improved.

  However, in general, the window layer requires a thickness of several tens of μm to several hundreds of μm. However, when such a window layer is grown by a semiconductor layer using a vapor phase growth method such as an MOCVD method, it is very long. There is a problem that it requires growth time and is difficult to manufacture.

Therefore, Patent Document 1 discloses a light emitting layer made of an AlGaAs layer grown on a GaAs substrate, a window layer (output coupling layer) made of an AlGaAs layer provided on the infrared irradiation side of the light emitting layer, and a window layer. A semiconductor light emitting device provided with a part of the upper surface of the semiconductor light emitting device is disclosed. In the semiconductor light emitting device of this Patent Document 1, after the epitaxial growth is performed up to the light emitting layer by the vapor phase growth method, the window layer is epitaxially grown by the liquid phase growth method. Thereby, in the semiconductor light emitting device of Patent Document 1, it was possible to easily form a window layer having a thickness of several tens of μm or more.
JP 2000-516768 gazette

  However, when the window layer is epitaxially grown by the liquid phase growth method, the materials applicable to the window layer are limited in terms of lattice matching between the window layer and the semiconductor layer including the light emitting layer formed under the window layer. There is a problem of being. For this reason, there is a problem that the window layer cannot be formed from an inexpensive material and the manufacturing cost increases.

  The present invention has been made to solve the above-described problems, and provides a semiconductor light-emitting device and a method for manufacturing the semiconductor light-emitting device that can have a high degree of freedom in selecting a material that can be applied to the window layer and can suppress manufacturing costs. The purpose is to do.

  In order to achieve the above object, the invention described in claim 1 includes a semiconductor layer including a light emitting layer capable of emitting infrared rays, and an insulating window layer capable of transmitting the infrared rays, wherein the window layer includes: A semiconductor light-emitting element is attached to the semiconductor layer.

  The invention according to claim 2 is the semiconductor light emitting element according to claim 1, wherein the light emitting layer has a first light emitting layer and a second light emitting layer capable of emitting infrared rays having different wavelengths. is there.

  The invention according to claim 3 is a semiconductor light emitting element according to claim 1, further comprising a reflective layer capable of reflecting infrared light emitted from the light emitting layer. is there.

  According to a fourth aspect of the present invention, there is provided a semiconductor layer forming step of forming a semiconductor layer including a light emitting layer capable of emitting infrared light on a growth substrate, a substrate removing step of removing the growth substrate, and the growth substrate comprising: A method of manufacturing a semiconductor light emitting device, comprising: an attaching step of attaching an insulating window layer capable of transmitting infrared rays to the semiconductor layer in the removed region.

  The invention according to claim 5 is the semiconductor light emitting element according to claim 4, wherein in the attaching step, the window layer and the semiconductor layer are attached by thermocompression bonding or anodic bonding. It is a manufacturing method.

  The invention according to claim 6 is the method for manufacturing a semiconductor light emitting element according to claim 4, wherein in the attaching step, the window layer and the semiconductor layer are attached by polymer bonding. It is.

  According to the semiconductor light emitting device of the present invention, since the semiconductor layer and the window layer are pasted, the material of the window layer can be selected without considering the lattice matching of the materials constituting the semiconductor layer and the window layer. it can. As a result, the degree of freedom in selecting the material constituting the window layer can be increased, so that it is possible to select an inexpensive material such as glass or a material that easily transmits infrared rays. Furthermore, the window layer can be easily thickened by selecting a material that can be easily thickened.

  Further, by providing the first light emitting layer and the second light emitting layer capable of emitting infrared rays having different wavelengths, one semiconductor light emitting element can be used for two purposes.

  Further, by providing the reflective layer, infrared light traveling in a direction different from the desired direction can be reflected in the desired direction, so that the emission intensity can be improved.

  Further, by removing the growth substrate, it is possible to suppress absorption of infrared rays by the growth substrate, so that the intensity of infrared rays irradiated to the outside can be further improved.

  In addition, by attaching the semiconductor layer and the window layer by thermocompression bonding or anodization, it is possible to suppress the presence of an obstacle between the semiconductor layer and the window layer when infrared rays are transmitted.

  In addition, by pasting the semiconductor layer and the window layer by polymer bonding, even if a certain degree of irregularities are formed on the surface of the semiconductor layer and the surface of the window layer, the planarization process of both surfaces can be performed. It can be simplified.

  Embodiments in which the present invention is applied to a semiconductor light emitting element for optical communication capable of emitting infrared rays of two wavelengths will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a semiconductor light emitting device according to an embodiment of the present invention.

  As shown in FIG. 1, the semiconductor light emitting element 1 includes a window layer 2 and a semiconductor layer 3 attached on the window layer 2. Further, the semiconductor light emitting device 1 includes a p-side electrode 9 and an n-side electrode 10.

The window layer 2 is for reducing the ratio of infrared rays reflected at the interface with the outside. The window layer 2 has a thickness of several μm to several hundred μm, preferably about 30 μm to about 300 μm, and is made of insulating glass (SiO ₂ ) capable of transmitting infrared rays and having a high refractive index. Here, the high refractive index means that it has a refractive index equivalent to or higher than that of a semiconductor layer (for example, GaP having a refractive index of 3.45).

  In the semiconductor layer 3, an n-type cladding layer 4, a first light-emitting layer 5, a second light-emitting layer 6, a p-type cladding layer 7, and a reflective layer 8 are laminated in order from the window layer 2 side.

The n-type cladding layer 4 has a thickness of about 500 nm and is made of an n-type Al _0.5 Ga _0.5 As layer doped with silicon as an n-type dopant. The first light emitting layer 5 to the reflective layer 8 formed on a part of the upper surface of the n-type cladding layer 4 are removed so that the n-type cladding layer 4 is exposed.

The first light emitting layer 5 is for emitting infrared rays for IrDA optical communication having a wavelength of about 850 nm. The first light emitting layer 5 includes a well layer (not shown) made of a GaAs layer having a thickness of about 6 nm, and a barrier layer (not shown) made of an Al _0.3 Ga _0.7 As layer having a thickness of about 8 nm. Have an MQW (Multi quantum well) structure in which 70 pairs are alternately stacked.

The second light emitting layer 6 is for emitting infrared rays for sensors having a wavelength of about 950 nm. The second light emitting layer 6 is composed of an In _0.2 Ga _0.8 As layer having a thickness of about 10 nm.

The p-type cladding layer 7 has a thickness of about 500 nm and is composed of a p-type Al _0.5 Ga _0.5 As layer doped with zinc as a p-type dopant.

The reflection layer 8 is for reflecting the infrared rays reflected from the first light emitting layer 5 and the second light emitting layer 6 and traveling in the direction of arrow A to travel in the direction of arrow B (infrared irradiation direction). The reflective layer 8 has a DBR (Distributed Bragg Reflector) structure in which 10 pairs of p-type Al _0.8 Ga _0.2 As layers having a thickness of about 70 nm and p-type GaAs layers having a thickness of about 60 nm are alternately stacked. Have. The Al _0.8 Ga _0.2 As layer and the GaAs layer are doped with zinc as a p-type dopant.

  The n-type cladding layer 4 to the reflective layer 8 are formed on the growth substrate 21 described later by epitaxial growth.

  The p-side electrode 9 has a structure in which a plurality of metal layers are stacked, and is formed in an ohmic connection with a part of the upper surface of the reflective layer 8. The n-side electrode 10 has a structure in which a plurality of metals are stacked, and is formed in an ohmic connection with a part of the upper surface of the n-type cladding layer 4.

  Next, the operation of the semiconductor light emitting element described above will be described.

  First, when a current is supplied to the semiconductor light emitting element 1 via the p-side electrode 9 and the n-side electrode 10, holes are supplied from the p-side electrode 9 and electrons are supplied from the n-side electrode 10. Then, holes are injected into the light emitting layers 6 and 5 through the reflective layer 8 and the p-type cladding layer 7. Electrons are injected into the light emitting layers 5 and 6 through the n-type cladding layer 4.

  Then, the holes and electrons injected into the first light emitting layer 5 are combined to emit infrared light having a wavelength of about 850 nm, and the holes and electrons injected into the second light emitting layer 6 are combined to form about 950 nm. Infrared light having a wavelength is emitted.

  Here, the infrared rays traveling in the arrow A direction are reflected by the reflective layer 8 and travel in the arrow B direction. The infrared rays traveling in the direction of arrow B are irradiated to the outside through the n-type cladding layer 4 and the window layer 2. Here, since the window layer 2 has a thickness of several μm to several hundred μm, the incident angle of infrared rays at the interface between the window layer 2 and the outside becomes small. Thereby, the ratio of the infrared rays totally reflected is reduced, and the intensity of the infrared rays irradiated to the outside can be increased.

  Next, a method for manufacturing the semiconductor light emitting element described above will be described. 2 to 4 are diagrams for explaining a manufacturing process of the semiconductor light emitting element.

  First, the growth substrate 21 made of n-type GaAs is carried into the MOCVD apparatus.

Next, as shown in FIG. 2, trimethylaluminum (hereinafter referred to as TMA), trimethylgallium (hereinafter referred to as TMG), arsine and monosilane are supplied by a carrier gas (H ₂ gas), and about 500 nm of silicon doped. An n-type cladding layer 4 made of an n-type Al _0.5 Ga _0.5 As layer having a thickness is formed.

Next, TMG and arsine are supplied by a carrier gas to form a well layer made of a GaAs layer having a thickness of about 6 nm. Thereafter, TMA, TMG, and arsine are supplied by a carrier gas to form a barrier layer made of an Al _0.3 Ga _0.7 As layer having a thickness of about 8 nm. Then, the first light emitting layer 5 is formed by alternately stacking 70 p pairs of these well layers and barrier layers.

Next, trimethylindium (hereinafter referred to as TMI), TMG and arsine are supplied by a carrier gas to form the second light emitting layer 6 composed of an In _0.2 Ga _0.8 As layer having a thickness of about 10 nm.

Next, TMA, TMG, arsine and dimethylzinc are supplied by a carrier gas, and a p-type cladding layer 7 made of a p-type Al _0.5 Ga _0.5 As layer having a thickness of about 500 nm doped with zinc is formed. Form.

Next, TMA, TMG, arsine, and dimethylzinc are supplied with a carrier gas to form a p-type Al _0.8 Ga _0.2 As layer having a thickness of about 70 nm doped with zinc. Thereafter, TMG, arsine, and dimethylzinc are supplied by a carrier gas to form a p-type GaAs layer having a thickness of about 60 nm doped with zinc. Then, 10 pairs of these p-type Al _0.8 Ga _0.2 As layers and p-type GaAs layers are alternately stacked to form the reflective layer 8.

  Next, as shown in FIG. 3, the growth substrate 21 is removed by polishing and wet etching.

Next, a window layer 2 made of an insulating transparent substrate made of SiO ₂ is prepared. Thereafter, the surface of the n-type cladding layer 4 and the surface of the window layer 2 are smoothed by CMP (Chemical Mechanical Polish). Thereafter, the surface of the n-type cladding layer 4 and the surface of the window layer 2 are subjected to a hydrophilic treatment with an alkaline solution such as a KOH aqueous solution.

  Next, as shown in FIG. 4, the surface of the n-type cladding layer 4 and the surface of the window layer 2 are brought into contact with each other through pure water. In this state, while heating the window layer 2 and the semiconductor layer 3 between room temperature and about 800 ° C., a pressure of several MPa to about 10 MPa is applied so that the window layer 2 and the n-type cladding layer 4 are not separated. Perform thermocompression bonding. As a result, the water responsible for initial bonding at the bonding interface between the window layer 2 and the n-type cladding layer 4 and the hydrogen-bonded OH group (hydroxyl group) are evaporated as water vapor to bond the window layer 2 and the n-type cladding layer 4 together. Let

  Next, the p-type cladding layer 7 to the first light emitting layer 5 are etched to expose a part of the upper surface of the n-type cladding layer 4. Thereafter, the p-side electrode 9 is formed on the upper surface of the p-type cladding layer 7, and the n-side electrode 10 is formed on the upper surface of the n-type cladding layer 4. Finally, the semiconductor light emitting device 1 is completed by being divided into device units.

  As described above, in the semiconductor light emitting device 1, since the window layer 2 and the n-type cladding layer 4 are attached, it is necessary to consider the lattice matching of the materials constituting the n-type cladding layer 4 and the window layer 2. Therefore, the degree of freedom in selecting the material constituting the window layer 2 can be increased. For this reason, it is possible to select a material having a high refractive index, such as a glass substrate, which is inexpensive and easily transmits infrared rays. Furthermore, the window layer 2 can be easily thickened by using a glass substrate.

  Further, by removing the growth substrate 21 made of n-type GaAs that absorbs infrared rays, the absorbed infrared rays can be reduced, so that the intensity of infrared rays irradiated to the outside can be further improved.

  Moreover, since the semiconductor light emitting device 1 includes the first light emitting layer 5 and the second light emitting layer 6 that can emit infrared rays having different wavelengths, the single semiconductor light emitting device 1 can be used for two purposes.

  Moreover, since the semiconductor light emitting element 1 is provided with the reflective layer 8, the infrared rays traveling in the arrow A direction can be reflected and taken out in the arrow B direction. Thereby, the light emission intensity can be improved.

  In addition, by attaching the window layer 2 and the n-type cladding layer 4 by thermocompression bonding, it is possible to suppress the presence of an obstacle between the window layer 2 and the n-type cladding layer 4 when infrared rays are transmitted. it can. Furthermore, since the hydrophilic treatment of the surfaces of the window layer 2 and the n-type cladding layer 4 is performed using an alkaline solution, it can be implemented with inexpensive equipment and materials.

  As mentioned above, although this invention was demonstrated in detail using embodiment, this invention is not limited to embodiment described in this specification. The scope of the present invention is determined by the description of the claims and the scope equivalent to the description of the claims. Hereinafter, modified embodiments in which the above-described embodiment is partially modified will be described.

  As a modified form of the embodiment described above, a modified form in which a part of the pasting process is changed will be described.

(First modification)
In the first modification, after removing the growth substrate 21 from the semiconductor layer 3, a thickness of about 1 μm to about 10 μm is applied to the surface of at least one of the window layer 2 and the n-type cladding layer 4 by spin coating. Apply with. In addition, as a bonding agent, for example, a polyimide-based polymer or a cyclobran-based polymer can be applied. Next, the solvent is evaporated from the bonding agent by baking, and the surface of the window layer 2 and the surface of the n-type cladding layer 4 are brought into contact with each other. Thereafter, the window layer 2 and the n-type cladding layer are heated by heating the window layer 2 and the semiconductor layer 3 to the vicinity of the glass transition point of the bonding agent while applying pressure so as to maintain the contact between the window layer 2 and the n-type cladding layer 4. 4 is polymer-bonded. In the first modification, bonding can be performed even if there are irregularities of several μm on the surfaces of the window layer 2 and the n-type cladding layer 4, so that the process for smoothing both surfaces can be simplified. .

(Second modification)
In the second modification, the window layer 2 and the n-type cladding layer 4 are bonded by anodic bonding instead of bonding by heating and pressing in the above-described embodiment.

(Third modification)
In the third modified embodiment, the surface of the window layer 2 and the n-type cladding layer 4 is activated and hydrophilized by oxygen plasma ashing under conditions of about 1000 W and about 10 MHz instead of the hydrophilization treatment with the alkaline solution in the above-described embodiment. Process. In the fourth modification, the surface of the window layer 2 and the n-type cladding layer 4 can be made hydrophilic even with a material that is difficult to be hydrophilized with an alkaline aqueous solution.

  Moreover, in the above-mentioned embodiment, although glass was applied as the window layer 2, you may comprise the window layer 2 with the insulating material which can permeate | transmit infrared rays, such as quartz.

  In the above-described embodiment, the semiconductor light emitting device 1 including the two light emitting layers 5 and 6 is taken as an example. However, only one light emitting layer or three or more light emitting layers may be provided.

  Moreover, the thickness and material of each layer of the semiconductor light emitting element 1 can be changed as appropriate.

1 is a cross-sectional view of a semiconductor light emitting device according to an embodiment of the present invention. It is a figure for demonstrating the manufacturing process of a semiconductor light-emitting device. It is a figure for demonstrating the manufacturing process of a semiconductor light-emitting device. It is a figure for demonstrating the manufacturing process of a semiconductor light-emitting device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor light-emitting device 2 Window layer 3 Semiconductor layer 4 N-type clad layer 5 1st light-emitting layer 6 2nd light-emitting layer 7 p-type clad layer 8 Reflective layer 9 p-side electrode 10 n-side electrode 21 Growth substrate

Claims (6)

A semiconductor layer including a light emitting layer capable of emitting infrared rays;
An insulating window layer capable of transmitting the infrared rays,
The semiconductor light emitting element, wherein the window layer is attached to the semiconductor layer.   2. The semiconductor light emitting device according to claim 1, wherein the light emitting layer includes a first light emitting layer and a second light emitting layer capable of emitting infrared rays having different wavelengths.   The semiconductor light-emitting element according to claim 1, further comprising a reflective layer capable of reflecting infrared light emitted from the light-emitting layer. Forming a semiconductor layer including a light emitting layer capable of emitting infrared light on a growth substrate; and
A substrate removal step of removing the growth substrate;
A method of manufacturing a semiconductor light emitting device, comprising: an attaching step of attaching an insulating window layer capable of transmitting infrared light to the semiconductor layer in a region where the growth substrate is removed.   5. The method of manufacturing a semiconductor light emitting element according to claim 4, wherein in the attaching step, the window layer and the semiconductor layer are attached by thermocompression bonding or anodic bonding.   The method for manufacturing a semiconductor light emitting element according to claim 4, wherein in the attaching step, the window layer and the semiconductor layer are attached by polymer bonding.

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