KR20090026688A

KR20090026688A - Semiconductor light emitting device and fabrication method thereof

Info

Publication number: KR20090026688A
Application number: KR1020070091806A
Authority: KR
Inventors: 한영헌
Original assignee: 엘지이노텍 주식회사
Priority date: 2007-09-10
Filing date: 2007-09-10
Publication date: 2009-03-13

Abstract

An embodiment of the present invention relates to a semiconductor light emitting device.

A semiconductor light emitting device according to an embodiment of the present invention includes a first conductive semiconductor layer formed of a hexagonal concave-convex structure; An active layer formed on the first conductive semiconductor layer; And a second conductive semiconductor layer formed on the active layer.

Description

Semiconductor light emitting device and method of manufacturing the same {Semiconductor light emitting device and fabrication method

An embodiment of the present invention relates to a semiconductor light emitting device and a method of manufacturing the same.

Group III-V nitride semiconductors are spotlighted as core materials of light emitting devices such as light emitting diodes (LEDs) or laser diodes (LDs) due to their physical and chemical properties.

Ⅲ-Ⅴ nitride semiconductor is made of a semiconductor material having a compositional formula of normal _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x + y≤1). BACKGROUND ART Light emitting devices for obtaining light of LEDs or LDs using such nitride semiconductor materials have been widely used, and have been applied to light sources of various products such as keypad light emitting units, electronic displays, and lighting devices of mobile phones.

1 is a side cross-sectional view of a conventional nitride semiconductor light emitting device, in particular showing a nitride semiconductor light emitting diode (LED) device.

Referring to FIG. 1, the light emitting device 10 has a structure in which an n-type GaN layer 13, an active layer 15, and a p-type GaN layer 17 are sequentially stacked on a sapphire substrate 11. A portion of the n-type GaN layer 13 is exposed by a mesa etching process. At this time, the n-side electrode 19 is formed on the exposed top surface of the n-type GaN layer 13, and the p-side electrode 21 is formed on the top surface of the p-type GaN layer 17.

The light emitting device 10 generates light by recombination of electrons and holes in the active layer and is emitted to the outside. In order to improve the efficiency in which such light is emitted to the outside, that is, the external quantum efficiency, research is being conducted.

An embodiment of the present invention provides a semiconductor light emitting device and a method of manufacturing the same that can improve light extraction efficiency and external quantum efficiency.

Method of manufacturing a semiconductor light emitting device according to an embodiment of the present invention comprises the steps of forming a first conductive semiconductor layer with a hexagonal uneven structure; Forming an active layer on the first conductive semiconductor layer; Forming a second conductive semiconductor layer on the active layer.

According to the semiconductor light emitting device according to the embodiment of the present invention, the light extraction efficiency can be improved by providing a hexagonal concave-convex structure in which the side surface is inclined at the interface of the light emitting device.

In addition, the surface area of the semiconductor layer, in particular, the active layer is increased by the hexagonal grooves and / or protrusions, thereby improving internal and external quantum efficiency.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

2 is a side cross-sectional view of a semiconductor light emitting device according to an exemplary embodiment of the present invention, and FIG. 3 is a plan view of the substrate of FIG. 2. 4 is a partial detail view of FIG. 2.

2 to 4, the semiconductor light emitting device 100 may include a substrate 110 having a hexagonal groove (concave or intaglio) 112, a buffer layer 120, a first conductive semiconductor layer 130, and an active layer. 140, a second conductive semiconductor layer 150, a transparent electrode layer 160, a first electrode layer 171, and a second electrode layer 173.

The substrate 110 may be selected from the group consisting of sapphire substrate (Al ₂ O ₃ ) and Si, and may be removed before forming the electrode of the light emitting device.

The substrate 110 has a hexagonal groove 112 as shown in FIG. 3, and the hexagonal groove 112 has three horizontal axes and an inclined side surface 113 that cross each other at an angle of 60 ° on a plane. ). The top of the inclined side 113 is formed with a substrate surface and a circular border. Here, the plane of the hexagonal groove 112 and the substrate surface 111 are C planes in a hexagonal system, and the inclined side surfaces 113 are A-plane and R-planes in a hexagonal system. , At least one of the M-planes.

The inclined side surface 113 of the hexagonal groove 112 is etched in the crystal direction of at least one of A-plane, R-plane, and M-plane in the hexagonal system, and thus at an inclination angle (= 54.7 °). It has a total reflection structure, thereby reducing the rate of absorption in the traveling path of the light, it is possible to improve the external quantum efficiency. The substrate 110 may be provided with an uneven structure 115 (111, 112, 113) using a hexagonal groove 112.

And, as shown in Figure 4, the depth (D1) of the hexagonal groove 112 is 10Å-300um with respect to the substrate surface 111, the diameter (D2) of the hexagonal groove 112 It becomes 1 ~ 500um. These hexagonal grooves 112 may be arranged at regular or irregular sizes and intervals. The interval between the hexagonal groove 112 and the groove 112 is 1 ~ 500um.

Here, although the hexagonal concave-convex structure 115 using the hexagonal grooves (ie, concave or intaglio) 112 has been described, the hexagonal projections (ie, iron or embossed) are used on the substrate surface. It is also possible to form a hexagonal uneven structure. In the description of the embodiment of the present invention, the hexagonal intaglio is described as an example, and the hexagonal embossment and the intaglio can be formed on the surface of the substrate, thereby providing a concave-convex structure using the hexagonal embossed and / or intaglio. Can be.

A portion of the uneven structure of the active layer 140, that is, the uneven portion 146 has an extension line P1 formed above the extension line P2 of the surface 111 of the substrate 110. The location of the portion 146 can be adjusted lower or higher by the thickness of the buffer layer 120, thereby reducing wave guiding of the light.

2 and 4, a buffer layer 120 is formed on the substrate 110, and the buffer layer 120 is a layer for reducing a difference in lattice constant from the substrate 110. AlN, AlGaN, InGaN and the like may be selectively formed. The buffer layer 120 is formed of an uneven structure 125 using the hexagonal grooves (or protrusions) formed on the surface of the substrate 110.

An undoped semiconductor layer (not shown) may be formed on the buffer layer 120, and the undoped semiconductor layer may be implemented as an undoped GaN layer. Only one of the buffer layer 120 and the undoped semiconductor layer may be formed on the substrate 110, or neither or both layers may be removed.

The first conductive semiconductor layer 130 is formed on the buffer layer 120. The first conductive semiconductor layer 130 is, for example, n-type to which may comprise a semiconductor layer, the n-type semiconductor layer is _{In x Al y Ga 1 -x- y} N (0≤x≤1, 0 ≤y A semiconductor material having a composition formula of ≤ 1, 0 ≤ x + y ≤ 1, for example, InAlGaN, GaN, AlGaN, InGaN, AlN, InN, etc. may be selected, and n-type dopants (eg, Si, Ge, Sn, etc.) Doped. The first conductive semiconductor layer 130 is formed of a concave-convex structure 135 using the hexagonal grooves on the surface of the buffer layer 120.

An active layer 140 is formed on the first conductive semiconductor layer 130, and the active layer 140 may be formed in a single or multiple quantum well structure. A conductive clad layer (not shown) may be formed on and under the active layer 140, and the conductive clad layer may be implemented as an AlGaN layer.

The active layer 140 is formed of a concave-convex structure 145 using hexagonal grooves on the first conductive semiconductor layer 130. The uneven structure 145 may increase the surface area of the active layer 140 and may improve internal quantum efficiency.

A second conductive semiconductor layer 150 is formed on the active layer 140, and the second conductive semiconductor layer 150 may be implemented as a p-type semiconductor layer, wherein the p-type semiconductor layer is In _x Al _y Ga. ₁ _-x- _y N semiconductor materials having a composition formula of (0≤x≤1, 0 ≤y≤1, 0≤x + y≤1) , for example, InAlGaN, can be selected from GaN, AlGaN, InGaN, AlN, InN P-type dopant (eg, Mg) is doped.

The transparent electrode layer 160 is formed on the second conductive semiconductor layer 150, and the second electrode layer 173 is formed on the transparent electrode layer 160. A third conductive semiconductor layer (not shown) may be further formed between the second conductive semiconductor layer 150 and the second electrode layer 173, and the transparent electrode layer 160 may not be formed. The transparent electrode layer 160 may be formed of at least one of ITO, ZnO, RuOx, TiOx, and IrOx.

The second conductive semiconductor layer 150 is formed of an uneven structure 155 using the hexagonal grooves on the active layer 140, and the transparent electrode layer 160 is formed on the second conductive semiconductor layer 150. It may be formed in a concave-convex structure using a hexagonal groove.

In addition, the first electrode layer 171 and the second electrode layer 173 may be formed in a concave-convex structure by the concave-convex structures 135 and 165 of the lower semiconductor layers 130 and 150.

As shown in FIG. 4, the semiconductor layers 120 to 150 on the substrate 110 have at least one of a C-plane, an A-plane, an R-plane, and an M-plane in a hexagonal system using hexagonal grooves. Due to the uneven structure 125 to 155 having a plane, light extraction efficiency may be improved.

5 to 7 are cross-sectional views illustrating a process of manufacturing the semiconductor light emitting device according to the first embodiment.

First, a pattern is formed on the substrate 110. To this end, an oxide film (not shown) is formed on the sapphire or silicon substrate 110 as shown in FIG. 5. The oxide film is a Si0 ₂ or SiN-based oxide film is deposited to a predetermined thickness (for example 0.1 ~ 0.6um). After the photoresist pattern 118 is formed on the oxide film (not shown), the oxide film is etched to expose the substrate surface as shown in FIG. 5.

Here, the oxide layer etching method may use a dry or / and a wet etching method. For example, buffered oxide etch (BOE), HF, and dry etching may be selectively used. As a result, an etching region 116 is formed between the oxide layer patterns 117.

Thereafter, the photoresist pattern 118 is removed.

The substrate etching step is then performed. When etching is performed on the surface of the substrate 110 by using the oxide layer pattern 117 of FIG. 5, the hexagonal groove 112 and the A-plane in the hexagonal system are formed in the substrate 110 as shown in FIG. 6. At least one plane of the plane, the M-plane, will form an inclined side surface 113. In this case, the substrate etching method may selectively use sulfuric acid (H ₂ SO ₄ ) and phosphoric acid (H ₃ PO ₄ ) or may use a chemical etching method.

Thereafter, the oxide pattern 117 remaining on the substrate 110 is removed. Here, not only the concave-convex structure having a hexagonal groove, but also the crystal structure of the substrate may be formed into a concave-convex structure having a hexagonal protrusion.

Referring to FIG. 7, the buffer layer 120, the first conductive semiconductor layer 130, the active layer 140, and the second layer are formed on the surface of the uneven structure 115 using the hexagonal grooves as shown in FIG. 2 on the substrate 110. The conductive semiconductor layer 150 is grown sequentially. At this time, due to the uneven structure of the hexagonal structure of the substrate 110, each layer 120 to 150 on the substrate 110 is formed of the uneven structure (125, 135, 1450, 155) using a hexagonal groove.

8 to 10 are semiconductor light emitting devices illustrating a second embodiment of the present invention. The second embodiment will not be repeated with respect to the same parts as the first embodiment.

Referring to FIG. 8, the semiconductor light emitting device 200 may include a buffer layer 220, a first conductive semiconductor layer 230, an active layer 240, and the like on a substrate 210 having a concave-convex structure 215 using a hexagonal groove. The second conductive semiconductor layer 250, the transparent electrode layer 260, and the first and second electrode layers 271 and 273 are included. In this case, the thickness of the buffer layer 220 is minimized.

The uneven structure 215 of the substrate 210 is formed as shown in FIG. 9, and the buffer layer 220, the first conductive semiconductor layer 230, and the active layer are formed in a hexagonal groove area of the substrate 210. At least a portion of the active layer 240 may be inserted into the recessed portion 240. That is, as shown in FIG. 10, the extension line P1 of the yaw portion of the active layer 240 is disposed below the extension line P2 of the surface of the substrate 210. This can minimize the wave guiding of the light emitted from the active layer 240 by allowing the recessed portion of the uneven structure 245 of the active layer 240 to be disposed in the hexagonal groove region of the substrate 210. have.

In addition, the concave-convex structure 215 using the hexagonal groove of the substrate 210 may be reflected in each layer as it is, thereby increasing the surface area of the active layer 240, thereby improving internal quantum efficiency. In addition, the uneven structures 225 to 255 of each of the semiconductor layers 220 to 250 may change the reflection angle at the interface to improve external quantum efficiency.

11 and 12 are diagrams illustrating a semiconductor light emitting device according to a third embodiment.

Referring to FIG. 11, an uneven structure 315 using a hexagonal groove is formed in the substrate 310. The buffer layer 320, the first conductive semiconductor layer 330, the active layer 340, and the second conductive semiconductor layer 350 are sequentially formed on the substrate 310. In addition, a second electrode layer 360 is formed on the second conductive semiconductor layer 350, and a conductive support substrate 370 is formed on the second electrode layer 360. The buffer layer 320 to the second conductive semiconductor layer 350 may be formed in a concave-convex structure using a hexagonal groove.

The second electrode layer 360 may include a reflective electrode layer and / or a transparent electrode layer, which are not shown, and may have a concave-convex structure using hexagonal grooves. Here, the reflective electrode layer may be implemented with one or a combination of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, Hf. The conductive support substrate 370 may be implemented with copper or gold.

In addition, a third conductive semiconductor layer (not shown) having a concave-convex structure using a hexagonal groove may be further formed on the second conductive semiconductor layer 350, as well as an NP or NPN structure, as well as a PN and PNP type junction. It can also be implemented as a structure.

When the conductive support substrate 370 is formed, the substrate 310 and the buffer layer 320 are removed. In this case, the method of removing the substrate 310 may be removed by a laser lift-off (LLO) method, and the buffer layer 320 may be removed by a physical or / and chemical removal method. Here, the substrate 310 and the buffer layer 320 may not be removed when the conductivity is good.

Referring to FIG. 12, a first electrode layer 371 is formed on the first conductive semiconductor layer 330 (as illustrated). The semiconductor light emitting device 300 functions as a vertical semiconductor light emitting device.

In the description of an embodiment according to the present invention, each layer (film), region, pattern or structure is "on" or "under" the substrate, each layer (film), region, pad or patterns. In the case where it is described as being formed in, "on" and "under" include both the meaning of "directly" and "indirectly". In addition, the criteria for the top or bottom of each layer will be described with reference to the drawings.

Although the present invention has been described above with reference to the embodiments, these are only examples and are not intended to limit the present invention, and those skilled in the art to which the present invention pertains may have an abnormality within the scope not departing from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not illustrated.

For example, each component shown in detail in the embodiment of the present invention may be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

1 is a side cross-sectional view showing a conventional semiconductor light emitting device.

2 is a side cross-sectional view showing a semiconductor light emitting device according to the first embodiment of the present invention.

3 is a plan view of a substrate in the light emitting device of FIG.

4 is a partially enlarged cross-sectional view of FIG. 2.

5 to 7 illustrate a process of manufacturing a semiconductor light emitting device according to the first embodiment of the present invention.

8 is a side sectional view showing a semiconductor light emitting device according to a second embodiment of the present invention;

9 is a plan view of a substrate in the light emitting device of FIG. 5;

10 is a partially enlarged view of FIG. 5;

11 and 12 are side cross-sectional views illustrating a semiconductor light emitting device according to a third embodiment of the present invention.

100,200,300: semiconductor light emitting device 110,210,310: substrate

111,211: Hexagon Grooves

115,125,135,145,155,215,225,235,245,255,315: uneven structure

120,220,320: buffer layer 130,230,330: first conductive semiconductor layer

140,240,340: active layer 150,250,350: second conductive semiconductor layer

160,260 transparent electrode layer 171,271,371 first electrode layer

173,273,360: second electrode layer 370: conductive support substrate

Claims

A first conductive semiconductor layer formed of a hexagonal uneven structure;

An active layer formed on the first conductive semiconductor layer;

A semiconductor light emitting device comprising a second conductive semiconductor layer formed on the active layer.

The method of claim 1,

The first conductive semiconductor layer is a plane of the concave-convex structure is a C-plane in the hexagonal system, the side of the concave or iron is at least one plane of the A-plane, R-plane and M-plane in the hexagonal system A semiconductor light emitting device characterized in that.

The method of claim 1,

The active layer and the second conductive semiconductor layer are formed on the first conductive semiconductor layer is a semiconductor light emitting device having a hexagonal concave-convex structure.

The method of claim 1,

And at least one of a buffer layer and an undoped semiconductor layer having a hexagonal concave-convex structure and a substrate having a hexagonal concave-convex structure under the first conductive semiconductor layer.

The method of claim 4, wherein

And a recessed portion of the buffer layer, the undoped semiconductor layer, the first conductive semiconductor layer, and the active layer, or the recessed portion of the active layer, inside the recessed structure.

The method of claim 4, wherein

Hexagonal yaw depth of the substrate is a semiconductor light emitting device formed of 10Å-300um.

The method of claim 4, wherein

The hexagonal concave portion of the substrate diameter of the semiconductor light emitting device is formed in 1-500um.

The method of claim 4, wherein

The interval between the hexagonal yaw and the yaw of the substrate is formed of 1-500um semiconductor light emitting device.

The method of claim 4, wherein

The substrate is a semiconductor light emitting device made of sapphire or silicon series.

The method of claim 1,

And at least one of a transparent electrode layer, a second electrode layer, a third conductive semiconductor layer, and a conductive support substrate on the second conductive semiconductor layer.

The method of claim 10,

At least one of the transparent electrode layer, the second electrode layer and the third conductive semiconductor layer is a semiconductor light emitting device formed of a hexagonal concave-convex structure.

Forming a first conductive semiconductor layer with a hexagonal uneven structure;

Forming an active layer on the first conductive semiconductor layer;

And forming a second conductive semiconductor layer on the active layer.

The method of claim 12,

In the hexagonal concave-convex structure, a plane is a C-plane in a hexagonal system, and a side surface is at least one plane among A-plane, R-plane, and M-plane in a hexagonal system. .

The method of claim 12,

The active layer and the second conductive semiconductor layer is a semiconductor light emitting device manufacturing method formed of a concave-convex structure corresponding to the concave-convex structure of the first conductive semiconductor layer.

The method of claim 12,

And a buffer layer and an undoped semiconductor layer having a hexagonal concave-convex structure under the first conductive semiconductor layer, and a substrate having a hexagonal concave-convex structure.

The method of claim 15,

The hexagonal concave-convex structure on the substrate,

Forming an oxide film on the substrate;

Forming an oxide layer pattern on the oxide layer using a photoresist pattern to expose an etching region on the surface of the substrate;

And etching the exposed surface of the substrate along the oxide layer pattern to form a hexagonal concave-convex structure.

The method of claim 16,

The substrate is etched using a semiconductor light emitting device using at least one of sulfuric acid and phosphoric acid.

The method of claim 16,

And a recessed portion of at least one of the buffer layer, the undoped semiconductor layer, the first conductive semiconductor layer, and the active layer or all layers is disposed in the recess of the hexagonal concave-convex structure of the substrate.

The method of claim 16,

The substrate is a semiconductor light emitting device manufacturing method comprising a sapphire substrate or a silicon substrate.