JP5685617B2 - Method for manufacturing light emitting diode device - Google Patents

Description

  The present invention relates to a method for manufacturing a light-emitting diode device using an n-type GaN layer as a main material, and a method for manufacturing a light-emitting diode device using an InAlGaN layer as a main material.

  Most GaN-based semiconductor materials grow on non-conductive sapphire substrates, so when fabricating LED devices, electrodes must be formed on the same surface by etching techniques. However, conventional wet etching is not applicable to GaN-based materials because it has very strong acid-alkali resistance. For this reason, in general, wet etching of GaN-based materials is unsuitable for mass production because the etching rate is too slow. For this reason, dry etching is almost always adopted. A method of dry etching a group semiconductor material is described. However, although dry etching can overcome the problem of wet etching, it is easy to form damage to the epitaxial layer. Therefore, there are many problems that dry etching forms on the device. Non-patent literature 1 reports that the surface is too rough or etching damage forms, which is as reported in Non-Patent Document 1, and in Non-Patent Documents 2 and 3, a mesa side wall (mesa sidewall) The problem of electrical leakage caused by the etching of is described. For this reason, it is necessary to solve the problem of etching in the GaN-based LED manufacturing process.

  In addition, there is a very large difference in refractive index between the III-V semiconductor GaN (n = 2.3) and air (n = 1), and the total reflection critical angle is only about 25 degrees. Therefore, most of the light rays of the light emitting layer are only totally reflected internally and are not emitted. In order to modify the structure of such an interface, the surface of the semiconductor has already been roughened so that the light beam is emitted from the light emitting layer and then the roughened layer interface is passed, the light beam is diffused to modify the path of incident light, Techniques have been provided to increase the probability of light emission after total reflection. Further, Non-Patent Document 4 describes that the luminous efficiency is clearly increased to 40% after roughening. A known roughening method is to etch an epitaxial surface. For example, Patent Document 2 describes a technique for roughening the surface of a light emitting device by chemical etching to achieve the effect of increasing luminous efficiency. Has been. Patent Documents 3 and 4 also describe related techniques. However, such a processing method is applied only to the red LED. The main cause is the property that material processing is relatively easy, and it is not applicable to GaN-based materials, which is due to the very strong acid-alkali resistance properties of GaN-based materials. Although dry etching overcomes the problem of wet etching, it tends to form epitaxial layer damage, and its p-type GaN pole is very prone to form an increase in electrical resistance, and growth of p-type GaN is usually If the p-type GaN is roughened very thinly (0.1 to 0.3 μm), the light emitting layer may be destroyed and the light emitting area may decrease. In general, the transparent electrode used in the GaN LED is very thin (10 nm) due to light transmission, so that the transparent electrode becomes discontinuous and affects current dispersion, and the luminous efficiency is lowered. For this reason, it is extremely difficult to directly roughen p-type GaN, and non-p-type GaN must be grown thick.

International Patent No. WO09854757 US Patent No. 5040044 US Pat. No. 5,429,954 US Pat. No. 5,898,192

Journal of Electronic, 27, No. 4,261,1998 Appl. Phys. Lett. 72, 1998 Jpn. J. et al. Appl. Phys. 37, L1202, 1998 IEEE Transactions on Electron Devices, 47 (7), 1492, 2000

  In order to solve the above-mentioned problems of the prior art, the present invention provides a method for exposing n-type GaN without the need to etch the semiconductor material, thereby improving the problems formed by etching. To do. The present invention provides a method for manufacturing a GaN-based light emitting device, which can provide a light emitting device that prevents various problems formed by etching as compared with a conventional light emitting device.

  In addition, in order to solve the problem of total internal reflection described in the rear part of the above-mentioned prior art, the present invention also provides a roughening diffusion effect by a method of filling a local area of the InAlGaN layer with an SiO2 layer during the epitaxial process. And thereby improve the luminous efficiency of the GaN-based light emitting device. The present invention provides a method capable of achieving the roughening effect without roughening the p-type GaN in the GaN-based light emitting device. According to the present invention, the conventional light emitting device can be obtained without destroying the p-type GaN or the light emitting layer. Compared with the light emitting device, the light emitting efficiency is clearly improved.

The invention of claim 1 is a method of manufacturing a light emitting diode device,
Forming a first semiconductor layer on the substrate;
Forming an isolation layer on the first semiconductor layer;
Removing a portion of the isolation layer to expose a portion of the first semiconductor layer;
Forming a light emitting diode structure in a partial region removed in a previous step of the isolation layer;
Removing the other isolation layer on the first semiconductor layer and exposing another portion of the first semiconductor layer without etching the semiconductor layer;
Forming an ohmic contact electrode on the exposed first semiconductor layer without etching the semiconductor layer;
The manufacturing method of the light emitting diode device includes the above steps.
According to a second aspect of the present invention, in the method of manufacturing a light emitting diode device according to the first aspect, the step of forming the light emitting diode structure further comprises:
Forming a light emitting active layer on the first semiconductor; and
Forming a second semiconductor layer on the light emitting active layer;
It is set as the manufacturing method of the light emitting diode device characterized by including these.
According to a third aspect of the present invention, in the method of manufacturing a light emitting diode device according to the second aspect, the first semiconductor layer is an n-type GaN-based III-V group compound, and the light emitting active layer has a multiple quantum well structure. The second semiconductor layer is made of a p-type GaN-based III-V group compound, which is a method for manufacturing a light-emitting diode device.
According to a fourth aspect of the present invention, in the method for manufacturing a light emitting diode device according to the third aspect, a p-type ohmic contact electrode is further formed on the second semiconductor layer, and the ohmic contact on the first semiconductor layer is formed. The electrode is an n-type ohmic contact electrode, which is a method for manufacturing a light-emitting diode device.
According to a fifth aspect of the present invention, in the method of manufacturing a light emitting diode device according to the fourth aspect, the material of the substrate is sapphire, the material of the n-type ohmic contact electrode is Ti / Al, and the p-type ohmic contact. The electrode is made of Ni / Au, and the isolation layer is made of SiO ₂ , which is a method for manufacturing a light-emitting diode device.
According to a sixth aspect of the present invention, in the method of manufacturing a light emitting diode device according to the first aspect, the buffer layer is formed between the semiconductor layer on the substrate. Yes.
According to a seventh aspect of the present invention, in the method for manufacturing a light emitting diode device according to the sixth aspect, the method for forming the buffer layer is a MOCVD method.
According to an eighth aspect of the present invention, in the method of manufacturing a light emitting diode device according to the second aspect, the isolation layer has a thickness of 0.5 to 1 μm, the first semiconductor layer has a thickness of 2 to 4 μm, and the second semiconductor The thickness of the layer is 0.1 to 0.2 μm, and this is a method for manufacturing a light-emitting diode device.
According to a ninth aspect of the present invention, in the method for manufacturing a light emitting diode device according to the sixth aspect, the buffer layer is made of GaN and the thickness thereof is 20 to 50 nm. It is said.
According to a tenth aspect of the present invention, in the method for manufacturing a light emitting diode device according to the second aspect, the isolation layer is formed by a PECVD method, and the light emitting active layer is formed by a MOCVD method. The manufacturing method.

  The present invention provides a method for exposing n-type GaN without the need to etch the semiconductor material, thereby improving the problems formed by etching. The present invention provides a method for manufacturing a GaN-based light emitting device, which can provide a light emitting device that prevents various problems formed by etching as compared with a conventional light emitting device.

The present invention also achieves a rough diffusion effect by filling the SiO ₂ layer locally in the InAlGaN layer during the epitaxial process, thereby improving the luminous efficiency of the GaN-based light emitting device. The present invention provides a method capable of achieving the roughening effect without roughening the p-type GaN in the GaN-based light emitting device. According to the present invention, the conventional light emitting device can be obtained without destroying the p-type GaN or the light emitting layer. Compared with the light emitting device, the light emitting efficiency is clearly improved.

It is a summary display figure of the manufacture process of the light emitting diode apparatus which uses GaN as the main material of 1st Example of this invention. It is a general | schematic display figure of the manufacturing process of the light emitting diode apparatus which uses InAlGaN of 2nd Example of this invention as a main material. It is a general | schematic display figure of the manufacturing process of the light emitting diode apparatus which uses InAlGaN of 2nd Example of this invention as a main material. It is a general | schematic display figure of the manufacturing process of the light emitting diode apparatus which uses InAlGaN of 2nd Example of this invention as a main material. It is a general | schematic display figure of the manufacturing process of the light emitting diode apparatus which uses InAlGaN of 2nd Example of this invention as a main material. It is a general | schematic display figure of the manufacturing process of the light emitting diode apparatus which uses InAlGaN of 2nd Example of this invention as a main material. It is a general | schematic display figure of the manufacturing process of the light emitting diode apparatus which uses InAlGaN of 2nd Example of this invention as a main material. It is a summary display figure of the manufacture process of the light emitting diode apparatus which uses InAlGaN of 3rd Example of this invention as a main material. It is a summary display figure of the manufacture process of the light emitting diode apparatus which uses InAlGaN of 3rd Example of this invention as a main material. It is a summary display figure of the manufacture process of the light emitting diode apparatus which uses InAlGaN of 3rd Example of this invention as a main material. It is a summary display figure of the manufacture process of the light emitting diode apparatus which uses InAlGaN of 3rd Example of this invention as a main material. It is a summary display figure of the manufacture process of the light emitting diode apparatus which uses InAlGaN of 3rd Example of this invention as a main material. It is a summary display figure of the manufacture process of the light emitting diode apparatus which uses InAlGaN of 3rd Example of this invention as a main material.

The present invention is an n-type GaN layer on the surface of the wafer by epitaxial growth, the interface layer SiO ₂ was added, by lithography, to prepare a mesa (mesa) on the surface of SiO _2, and removing the SiO ₂ of the mesa In addition, the n-type GaN layer is exposed, and a light emitting diode structure is epitaxially grown on the wafer in the mesa region by MOCVD. Depending on the characteristics of the selectively epitaxially grown GaN epitaxial layer, a pn coplanar structure is formed, and finally SiO ₂ is removed to obtain a pn coplanar light emitting diode structure. As a result, the present invention completes the pn-coplanar structure necessary for the LED device without using an etching process, thereby solving a number of problems formed by etching.

The present invention also provides an epitaxial growth of InAlGaN, followed by a lithography process to form a groove in the surface, remove the local region and expose the substrate, and grow a SiO ₂ layer in the groove, and finally A light emitting diode structure is formed thereon to form a light emitting diode device. By providing the diffusion effect using this SiO ₂ as a diffusion layer, the light emitted from the light emitting layer is diffused by this diffusion layer and the total reflection is reduced, thereby increasing the light emission efficiency.

In order to solve the above-mentioned object of the present invention, the sapphire substrate (1) is placed in an MOCVD system as shown in FIG. 1 and is 20 to 50 nm thick at 500 to 600 ° C. The GaN buffer layer (2) is grown. Subsequently, the substrate temperature is increased to 1000 to 1200 ° C. to grow a silicon doped GaN layer having a thickness of 2 to 4 μm. Thereafter, the wafer is taken out, and 0.5 to 1 μm of SiO ₂ (3) is grown by PECVD. Subsequently, SiO ₂ in the mesa region (4) is removed by a lithography process. Subsequently, this wafer is placed in a MOCVD system at 700 to 900 ° C., and an InGaN / GaN multiple quantum well structure (5) is grown in the mesa region to form a light emitting layer. Thereafter, the substrate temperature is raised to 1000 to 1200 ° C. to grow a single layer of a magnesium-doped GaN contact layer having a thickness of 0.1 to 0.2 μm. Finally, this wafer is taken out, and SiO ₂ other than the mesa region is removed, and thus a light emitting diode epitaxial structure (10) having the same surface as that of pn is completed. Further, Ni / Au is formed on the p-type GaN surface to form a p-type ohmic contact electrode (7), and Ti / Al is formed on the n-type GaN surface to form an n-type ohmic contact electrode (8). The die structure of the present invention is formed.

In order to specifically implement the object described in the rear part of the problem to be solved by the above-described invention, the present invention adopts the following scheme. Please refer to FIG. 2 to FIG. First, the sapphire substrate (11) is placed in an MOCVD system, and an InAlGaN layer (12) having a thickness of more than 0.1 μm is grown. Subsequently, the wafer is taken out, and this InAlGaN which is a buffer layer by a lithography process and dry etching The layer (12) is etched to form a groove (14), and the thickness of the groove (14) is the thickness of the InAlGaN layer. Subsequently, SiO ₂ (13) is grown in this groove, and the wafer is further placed in MOCVD, and the substrate temperature is raised to 800-1200 ° C. to grow a silicon-doped InAlGaN layer having a thickness of 1-2 μm. Subsequently, the substrate temperature is lowered to 700 to 900 ° C., and an InGaN / GaN multiple quantum well structure (15) is grown to form a light emitting layer. Thereafter, the substrate temperature is raised to 1000 to 1200 ° C. to grow a magnesium-doped GaN contact layer (16) having a thickness of 0.1 to 0.2 μm, thus forming a light emitting diode epitaxial structure (20). For this epitaxial structure, some p-type GaN (magnesium-doped GaN contact layer (16)) and InGaN / GaN multiple quantum well structure (15) are removed by dry etching, and the n-type GaN surface is exposed. Further, a p-type ohmic contact electrode (17) is formed on the p-type GaN surface with Ni / Au, and an n-type ohmic contact electrode (18) is formed on the n-type GaN surface with Ti / Al, thus forming the die structure of the present invention. Complete.

Please refer to FIG. 8 to FIG. A sapphire substrate (21) is placed in a MOCVD system, and a 0.1 μm thick InAlGaN layer (22) is grown thereon. Subsequently, the wafer is taken out, and a groove (24) is etched on the InAlGaN buffer layer using a lithography process and dry etching, so that the depth of the groove is 0.2 to 5 μm deeper than the thickness of the InAlGaN layer. Subsequently, SiO ₂ (23) is grown in the trench, and the wafer is further placed in MOCVD, and the substrate temperature is raised to 800-1200 ° C. to grow a silicon-doped InAlGaN layer having a thickness of 1-2 μm. Subsequently, the substrate temperature is lowered to 700 to 900 ° C., and an InGaN / GaN multiple quantum well structure (25) is grown to form a light emitting layer. Thereafter, the substrate temperature is further raised to 1000 to 1200 ° C. to grow a magnesium-doped GaN contact layer (26) having a thickness of 0.1 to 0.2 μm, and an abnormal light-emitting diode epitaxial structure (30) is completed. The p-type GaN (magnesium-doped GaN contact layer (26)) and the InGaN / GaN multiple quantum well structure (25) are removed by dry etching on the epitaxial structure, and the n-type GaN surface is exposed. The p-type ohmic contact electrode (27) is formed on the p-type GaN surface with Ni / Au, and the n-type ohmic contact electrode (28) is formed on the n-type GaN surface with Ti / Al. Complete.

1 substrate 2 GaN buffer layer 3 SiO ₂ region 4 mesa region 5 multiple quantum well structure 7 p-type ohmic contact electrode 8 n-type ohmic contact electrode 10 light emitting diode epitaxial structure 11 substrate 12 InAlGaN layer 13 SiO ₂ region 14 groove 15 multiple quantum well Structure 16 GaN contact layer 17 p-type ohmic contact electrode 18 n-type ohmic contact electrode 20 light-emitting diode epitaxial structure 21 substrate 22 InAlGaN layer 23 SiO ₂ region 24 groove 25 multiple quantum well structure 26 GaN contact layer 27 p-type ohmic contact electrode 28 n Type ohmic contact electrode 30 light emitting diode epitaxial structure

Claims (10)

In the manufacturing method of the light emitting diode device,
Forming a buffer layer on the substrate;
Removing a portion of the buffer layer, forming a plurality of grooves in the buffer layer, exposing the substrate;
Forming an isolation layer on the substrate exposed in each of the plurality of grooves;
The buffer layer is continuously grown as a first semiconductor layer to fill the trench,
Forming a light emitting active layer on the first semiconductor layer;
Forming a second semiconductor layer on the light emitting active layer;
Removing a part of the deposited structure of the second semiconductor layer, the light emitting active layer and the first semiconductor layer, exposing the first semiconductor layer;
Forming a first ohmic contact electrode on the exposed first semiconductor layer and forming a second ohmic contact electrode on a portion of the second semiconductor layer;
Including the above steps ,
The method for manufacturing a light-emitting diode device, wherein the buffer layer is made of InAlGaN and has a thickness of 0.1 μm .   2. The method of manufacturing a light emitting diode device according to claim 1, wherein the first semiconductor layer is an n-type GaN-based III-V group compound, the light emitting active layer has a multiple quantum well structure, and the second semiconductor layer is A method for manufacturing a light-emitting diode device, characterized by being a p-type GaN-based III-V group compound.   3. The method of manufacturing a light emitting diode device according to claim 2, further comprising forming a p-type ohmic contact electrode on the second semiconductor layer, and the first ohmic contact electrode on the first semiconductor layer is an n-type. A method of manufacturing a light-emitting diode device, characterized by being an ohmic contact electrode. 4. The method of manufacturing a light emitting diode device according to claim 3, wherein the material of the substrate is sapphire, the material of the n-type ohmic contact electrode is Ti / Al, and the material of the p-type ohmic contact electrode is Ni / Au. The method for manufacturing a light emitting diode device is characterized in that the material of the isolation layer is SiO ₂ .   5. The method for manufacturing a light emitting diode device according to claim 1, wherein the buffer layer is formed between the first semiconductor layer on the substrate. Production method.   6. The method for manufacturing a light emitting diode device according to claim 1, wherein the buffer layer is formed by an MOCVD method.   The method of manufacturing a light emitting diode device according to claim 1, wherein the first semiconductor layer has a thickness of 1 to 2 μm, and the second semiconductor layer has a thickness of 0.1 to 0.2 μm. A method of manufacturing a light-emitting diode device. The method of manufacturing a light emitting diode device of any one of claims 1 7, wherein the isolation layer is formed by PECVD method, the light emitting active layer is characterized by being formed by the MOCVD method, the light emitting diode device Manufacturing method. The method of manufacturing a light emitting diode device of any one of claims 1 8, the depth of the grooves of said plurality of, respectively, deeper than the thickness of the buffer layer, the manufacturing method of the light emitting diode device. 10. The method for manufacturing a light emitting diode device according to claim 9 , wherein the depth of each of the plurality of grooves is 0.2 to 5 [mu] m deeper than the thickness of the buffer layer.

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