KR101158076B1 - method for fabricating light emitting diode having grooved semi-conductor layer and light emitting diode thereof - Google Patents

Abstract

The present invention relates to a method of manufacturing a light emitting diode having an uneven semiconductor layer and a light emitting diode for the same. In particular, the surface of the first conductive semiconductor layer emitting the generated light is uneven to produce a light emitting diode having improved luminous efficiency. A method and a light emitting diode therefor.

To this end, the present invention has a first conductive semiconductor layer having an upper surface and a lower surface, the upper surface of which is grown on a mother substrate having a concave-convex surface, and the concave-convex surface of the concave-convex surface of the concave-convex surface of the mother substrate; A second conductivity type semiconductor layer positioned on a lower surface side of the first conductivity type semiconductor layer; It provides a light emitting diode having an uneven semiconductor layer comprising an active layer interposed between the first conductive semiconductor layer and the second conductive semiconductor layer.

Vertical light emitting diodes, unevenness, light extraction efficiency

Description

Method for manufacturing a light emitting diode having an uneven semiconductor layer and a light emitting diode for the same {method for fabricating light emitting diode having grooved semi-conductor layer and light emitting diode

1 is a cross-sectional view of a conventional vertical light emitting diode.

2 is a cross-sectional view of a vertical light emitting diode according to an embodiment of the present invention.

3 to 5 are cross-sectional views illustrating a method of manufacturing a vertical light emitting diode having an uneven semiconductor layer according to an embodiment of the present invention.

6 is a cross-sectional view illustrating a method of manufacturing a vertical light emitting diode having an uneven semiconductor layer according to another exemplary embodiment of the present invention.

7A to 7C are exemplary cross-sectional views of an uneven part of a vertical light emitting diode having an uneven semiconductor layer according to an embodiment of the present invention.

DESCRIPTION OF THE REFERENCE SYMBOLS

1: mother board 2: insulating film

10,101: conductive substrate 20,102: second electrode

30,103: reflective layer 40,104: semiconductor layers

41,104a: first conductive semiconductor layer 42,104b: active layer

43, 104c: second conductivity-type semiconductor layer 50, 105: first electrode

100: vertical light emitting diode

The present invention relates to a method of manufacturing a light emitting diode having an uneven semiconductor layer and a light emitting diode for the same. In particular, the surface of the first conductive semiconductor layer emitting the generated light is uneven to produce a light emitting diode having improved luminous efficiency. A method and a light emitting diode therefor.

In general, a light emitting diode has a first conductive semiconductor layer, a second conductive semiconductor layer, and an active layer interposed between the semiconductor layers, and light is generated by the recombination of electrons and holes in the active layer and emitted to the outside. .

Recently, a vertical light emitting diode for reducing energy loss in a light emitting diode by shortening a recombination distance between electrons and holes has been disclosed, and FIG. 1 is a cross-sectional view for describing such a vertical light emitting diode.

Referring to FIG. 1, the first electrode 105, the first conductive semiconductor layer 104a, the second conductive semiconductor layer 104c, and the active layer 104b interposed between these conductive semiconductor layers are It is located on the conductive substrate 101. The reflective layer 103 may be interposed between the second conductive semiconductor layer 104c and the conductive substrate 101, and the second electrode 102 may be interposed between the reflective layer 103 and the conductive substrate 101.

The vertical light emitting diode is emitted from the active layer 104b by recombination of electrons and holes, and emits light to the outside through the side surface and the top surface of the first conductivity type semiconductor layer 104a. The reflective layer 103 reflects the light emitted or reflected from the active layer 104b to the conductive substrate 101 to the first conductivity type semiconductor layer 104a.

The vertical light emitting diode can adopt the conductive substrate 101 to easily dissipate heat generated in the active layer 104b to the outside, thereby preventing a decrease in luminous efficiency due to an increase in temperature and compared to a horizontal light emitting diode. By reducing the recombination length of the electrons and holes there is an advantage that can reduce the electrical energy loss. In addition, light emitted from the active layer 104b is refracted on the upper surface of the first conductivity-type semiconductor layer 104a, so that the viewing angle is considerably widened.

However, since the upper surface of the first conductivity type semiconductor layer 104a is formed as a flat surface, light reaching the upper surface at an incident angle of more than a critical angle is not emitted to the outside and proceeds toward the active layer 104b by total internal reflection. In particular, when the first conductivity-type semiconductor layer 104a is a gallium nitride (GaN) -based semiconductor layer, the refractive index is high as about 2.4, so the critical angle is small. Therefore, a large part of the light generated in the active layer 4b is not emitted directly to the outside, and the internal reflection is repeated, thereby causing light loss in the vertical light emitting diode. This light loss has a problem that leads to a decrease in light extraction efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and to provide a light emitting diode and a method of manufacturing the same, in which light loss due to internal reflection is prevented and light extraction efficiency is improved.

Another object of the present invention is to provide a light emitting diode having an optimal light extraction efficiency and a directivity angle according to the generated light frequency and a method of manufacturing the same.

According to an aspect of the present invention for achieving the above object, the upper and lower surfaces, but the upper surface separated from the mother substrate is grown on the mother substrate having one surface uneven by the insulating film pattern is uneven surface of the mother substrate A first conductivity type semiconductor layer that is uneven in an inverted phase on one surface; An insulating film pattern filling the unevenness of the uneven first conductive semiconductor layer; A second conductivity type semiconductor layer positioned on a lower surface side of the first conductivity type semiconductor layer; And an active layer interposed between the first conductive semiconductor layer and the second conductive semiconductor layer.

Preferably, the conductive substrate located on the lower surface side of the second conductive semiconductor layer; And a reflective layer interposed between the conductive substrate and the second conductive semiconductor layer.

More preferably, the first electrode is located in a partial region of the upper surface side of the first conductivity type semiconductor layer; And a second electrode interposed between the reflective layer and the conductive substrate.

More preferably, the convex portion of the concave and convex upper surface of the first conductive semiconductor layer has a shape of any one of a conical shape, a hemispherical shape, a square shape, and a square pyramid shape.

According to another aspect of the present invention for achieving the above object, a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer is formed on a mother substrate having a concave-convex surface, and on the second conductive semiconductor layer Forming a conductive substrate on the substrate, and separating the mother substrate to expose one surface of the first conductive semiconductor layer, the surface of which is concave and convex, to the reversed surface of the concave and convex surface of the mother substrate. It is characterized by.

Preferably, the method further includes forming a reflective layer on the second conductive semiconductor layer before forming the conductive substrate on the second conductive semiconductor layer.

More preferably, the method may further include forming a first electrode in a partial region on the exposed upper surface of the first conductive semiconductor layer, and forming a second electrode between the reflective layer and the conductive substrate.

More preferably, the convex portion of the concave-convex upper surface of the first conductive semiconductor layer is formed to have any one of a conical shape, a hemispherical shape, a square shape, or a square pyramid shape.

According to another aspect of the present invention for achieving the above object, after forming an insulating film on one surface of the mother substrate to form an uneven surface by etching the insulating film, an epitaxial lateral over-growth (ELOG) on the uneven surface Forming a first conductivity type semiconductor layer, forming an active layer and a second conductivity type semiconductor layer on the first conductivity type semiconductor layer, forming a conductive substrate on the second conductivity type semiconductor layer, and forming the mother substrate. It is characterized in that the light emitting diode manufacturing method having a concave-convex semiconductor layer comprising separating and exposing one surface of the concave-convex surface of the first conductivity-type semiconductor layer of the concave-convex surface of the mother substrate.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view of a vertical light emitting diode having an uneven semiconductor layer according to an exemplary embodiment of the present invention.

Referring to FIG. 2, a vertical light emitting diode 100 having an uneven semiconductor layer according to an exemplary embodiment of the present invention may include a conductive substrate 10, first and second electrodes 50 and 20, first and second electrodes. The second conductive semiconductor layers 41 and 43, the active layer 42, and the reflective layer 30 are included.

The conductive substrate 10 may be a metal or silicon (Si) substrate positioned on the lower surface side of the second conductive semiconductor layer 43 and having excellent thermal conductivity.

The reflective layer 30 is interposed between the conductive substrate 10 and the second conductive semiconductor layer, and may include silver (Ag) and / or aluminum (Al). The reflective layer 30 reflects the light generated by the active layer 42 to the upper portion of the vertical light emitting diode 100 and emits light.

The second electrode 20 is interposed between the conductive substrate 10 and the reflective layer 30, and the reflective layer 30 forms an ohmic contact with the second conductive semiconductor layer 43. It is used when it is not possible or when the contact resistance is large. For example, when the second conductivity-type semiconductor layer 43 is a P-type semiconductor, the second electrode 20 may include platinum (Pt), nickel (Ni) and / or titanium (Ti) / gold (Au). It may include. In addition, when the second conductivity-type semiconductor layer 43 is an N-type semiconductor, the second electrode 20 may include Ti and / or Al.

The first and second conductivity-type semiconductor layers 41 and 43 are formed of P-type and N-type, or N-type and P-type semiconductors, respectively, and are positioned above and below the active layer 42, respectively.

In particular, the first conductivity-type semiconductor layer 41 has upper and lower surfaces, and the upper surface has an uneven shape. The uneven upper surface of the first conductivity type semiconductor layer 41 is grown on a mother substrate having one uneven surface and then separated from the mother substrate to be uneven in a reversed phase of one uneven surface of the mother substrate.

Since the upper surface of the first conductive semiconductor layer 41 has an uneven shape, the vertical light emitting diode 100 has an improved light extraction performance compared to a conventional vertical light emitting diode having a flat light emitting surface. . This is because the unevenness serves to increase the critical angle of the light emitted.

The convex portions of the uneven upper surface of the first conductive semiconductor layer 41 may be hemispherical as shown in FIG. 2 or conical, rectangular, or square pyramid shaped as shown in FIGS. 7A to 7C, respectively. In general, when the light generated in the active layer 42 is blue, the luminous efficiency of the light emitting diode 100 is best when the hemispherical convex portion is provided. On the other hand, when the light generated in the active layer 42 is white, the luminous efficiency of the light emitting diode 100 is best when the hemispherical iron portion. The directing angle of the emitted light is larger when the iron portion is hemispherical or square pyramid-shaped than when the iron portion is conical.

In addition, the uneven surface of the upper surface of the first conductive semiconductor layer 41 is not formed by performing a separate process after forming the first conductive semiconductor layer 41, but is formed before the removal of the mother substrate. The process yield of 100) can be increased and manufacturing time can be reduced by shortening the manufacturing time.

The active layer 42 is interposed between the first and second conductivity type semiconductor layers 41 and 43 and may be a single quantum well or multiple quantum wells. The active layer 42 has a narrower bandgap than the first and second conductive semiconductor layers 41 and 43.

The semiconductor layers 41, 42, and 43 may be GaN-based semiconductor layers formed of (B, Al, Ga, In) N, respectively, but are not limited thereto, and may be other material layers such as ZnO.

The first electrode 50 is positioned in a partial region on the side of the first conductivity type semiconductor layer 41 and forms ohmic contact with the first conductivity type semiconductor layer 41 to contact the first electrode 50. Inflow / outflow of the current through the light emitting diode 100 through.

3 to 5 are cross-sectional views illustrating a method of manufacturing a vertical light emitting diode having an uneven semiconductor layer according to an embodiment of the present invention.

Hereinafter, a method of manufacturing a vertical light emitting diode having an uneven semiconductor layer according to an embodiment of the present invention will be described with reference to FIGS. 3 to 5.

Referring to FIG. 3, a first conductive semiconductor layer 41, an active layer 42, and a second conductive semiconductor layer 43 are formed on a mother substrate 1 having an uneven surface, and the second substrate is formed on the mother substrate 1 having an uneven surface. The reflective layer 30, the second electrode 20, and the conductive substrate 10 are sequentially formed on the conductive semiconductor layer 43.

The mother substrate 1 may be, for example, a sapphire substrate.

The first conductive semiconductor layer 41, the active layer 42, and the second conductive semiconductor layer 43 may be formed using metal organic chemical vapor deposition (MOCVD). The first and second conductivity-type semiconductor layers 41 and 43 may be formed of (B, Al, Ga, In) N, but are not limited thereto and may be formed of another material such as ZnO. Meanwhile, GaN-based P-type semiconductors and N-type semiconductors may be formed by doping magnesium (Mg) and silicon (Si), respectively.

The conductive substrate 10 may be formed using, for example, a plating technique, a physical vapor deposition technique or a chemical vapor deposition technique, or may be formed by bonding a metal substrate or a silicon substrate.

The reflective layer 30 may be formed of, for example, Ag and / or Al, and the second electrode 20 may include, for example, Pt, Ni, and / or Ti / Au.

Referring to FIG. 4, the mother substrate 1 is separated to expose one surface of the first conductivity-type semiconductor layer 41 in which the irregularities of the irregular surface of the mother substrate 1 are reversed.

The mother substrate 1 may be separated using, for example, a laser, or by polishing, dry etching or wet etching techniques.

When using a laser, it is preferable that the said mother substrate 1 is a light transmissive substrate which transmits laser light like a sapphire substrate. The laser is irradiated from the mother substrate 1 side, and the laser may be, for example, a KrF (248 nm) laser. Since the mother substrate 1 is a light transmissive substrate, the interface of the first conductive semiconductor layer 41 is decomposed by the absorbed energy at the interface between the mother substrate 1 and the first conductive semiconductor layer 41. The mother substrate 1 is separated to thereby expose the uneven top surface of the first conductivity-type semiconductor layer 41.

Meanwhile, a buffer layer (not shown) may be formed before forming the first conductivity type semiconductor layer 41. The buffer layer may also be formed of a GaN-based semiconductor using MOCVD. When the laser is irradiated, the buffer layer is decomposed by the absorbed radiation energy at the interface between the buffer layer and the mother substrate 1, and the mother substrate 1 is separated. After the mother substrate 1 is separated, the remaining buffer layer is removed using an etching technique or a polishing technique.

Referring to FIG. 5, the first electrode 50 is formed in a partial region on the exposed upper surface of the first conductivity type semiconductor layer 41. The first electrode 50 forms an ohmic contact with the first conductive semiconductor layer 41, and current flows in and out through the first electrode 50.

6 is a cross-sectional view illustrating a method of manufacturing a vertical light emitting diode having an uneven semiconductor layer according to another exemplary embodiment of the present invention.

Since the light emitting diode manufacturing method according to another embodiment of the present invention is mostly the same as the manufacturing method of the light emitting diodes shown in FIGS. 3 to 5, the difference will be described.

Referring to FIG. 6, after forming the insulating film 2 on one surface of the flat mother substrate 1, the insulating film 2 is etched to form an uneven surface. Thereafter, the first conductivity type semiconductor layer 41 is formed on the uneven surface by using an epitaxial lateral over-growth (ELOG) method. The ELOG method is described in detail in MRS Internet Journal Nitride Semiconductor Research 3.6 (1998) "Study of the Epitaxial Lateral Overgrowth (ELO) Process for GaN on Sapphire Using Scanning Electron Microscopy and Monochromatic Cathodoluminescence". An active layer 42 and a second conductive semiconductor layer 43 are formed on the first conductive semiconductor layer 41.

The insulating film 2 is made of a material in which gallium nitride (GaN) growth is not performed, for example, SiO 2 or SiN. When the gallium nitride is grown after the insulating film 2 is etched, the gallium nitride grows in a vertical direction to a predetermined thickness only in the portion of the mother substrate 1 exposed by the etching, and then the gallium nitride in the horizontal direction again. This grows and merges, and then the gallium nitride grows in the vertical direction again. The growth method is not only a high quality thin film can be obtained by the ELOG method, but also when the gallium nitride is grown to have a constant angle, the surface of the first conductivity-type semiconductor layer 41 in which the mother substrate 1 is separated and exposed. It can be made to have this desired uneven | corrugated shape.

Then, as shown in FIGS. 4 and 5, the mother substrate 1 is separated and one surface of the first conductivity-type semiconductor layer 41 is recessed in the reverse phase of the irregular surface of the mother substrate 1. Is exposed and the first electrode 50 is formed on a portion of the first conductivity-type semiconductor layer 41.

The invention being thus described, it will be obvious that the same way may be varied in many ways. Such modifications are intended to be within the spirit and scope of the invention as defined by the appended claims.

According to the present invention as described above there is an effect to provide a light emitting diode and a method of manufacturing the light emitting diode is improved by preventing the light loss due to internal reflection by the uneven surface of the conductive semiconductor layer is emitted light generated.

In addition, according to the present invention as described above by selecting the concave-convex shape of the surface of the conductive semiconductor layer that emits light in accordance with the frequency of the generated light to provide a light emitting diode having an optimal light extraction efficiency and directing angle and a method of manufacturing the same It also works.

Claims (12)

A first conductivity type semiconductor layer having upper and lower surfaces, wherein the first conductive semiconductor layer is grown on a mother substrate having an uneven surface by an insulating film pattern, and the upper surface separated from the mother substrate is uneven in an inverted phase of the uneven surface of the mother substrate; An insulating film pattern filling the unevenness of the uneven first conductive semiconductor layer; A second conductivity type semiconductor layer positioned on a lower surface side of the first conductivity type semiconductor layer; And An active layer interposed between the first conductive semiconductor layer and the second conductive semiconductor layer; A light emitting diode having an uneven semiconductor layer comprising a. The method according to claim 1, A conductive substrate positioned on a lower surface of the second conductive semiconductor layer; A reflective layer interposed between the conductive substrate and the second conductive semiconductor layer; A light emitting diode having an uneven semiconductor layer further comprising. The method according to claim 2, A first electrode positioned in a partial region of the upper surface side of the first conductive semiconductor layer; A second electrode interposed between the reflective layer and the conductive substrate; A light emitting diode having an uneven semiconductor layer further comprising. The light emitting diode of claim 1, wherein the convex portion of the concave and convex upper surface of the first conductive semiconductor layer has any one of a conical shape, a hemispherical shape, a square shape, and a square pyramid shape. delete delete delete delete After forming an insulating film on one surface of the mother substrate to form an uneven surface by etching the insulating film, Forming a first conductive semiconductor layer on the uneven surface by using an epitaxial lateral over-growth method; An active layer and a second conductive semiconductor layer are formed on the first conductive semiconductor layer, Forming a conductive substrate on the second conductive semiconductor layer, And separating the mother substrate to expose one surface of the first conductive semiconductor layer, which is concave and convex in the reverse phase of the concave and convex surface of the mother substrate. The method of claim 9, Before forming the conductive substrate on the second conductive semiconductor layer, forming a reflective layer on the second conductive semiconductor layer. The method of claim 10, Forming a first electrode on a partial region on the exposed upper surface of the first conductivity type semiconductor layer, A method of manufacturing a light emitting diode having an uneven semiconductor layer, further comprising forming a second electrode between the reflective layer and the conductive substrate. The method of claim 9, wherein the convex portion of the concave-convex top surface of the first conductive semiconductor layer is formed to have any one of a conical shape, a hemispherical shape, a square shape, and a square pyramid shape.

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