KR20090085877A - Vertical structure semiconductor light emitting device manufacturing method - Google Patents

Abstract

The present invention relates to a method for manufacturing a vertical semiconductor light emitting device, and a preferred embodiment of the present invention includes forming an etch stop layer having an opening on a substrate for semiconductor single crystal growth, and for growing the semiconductor single crystal through the opening. Sequentially growing an n-type nitride semiconductor layer, an active layer and a p-type nitride semiconductor layer on the substrate and the etch stop layer, forming a conductive substrate on the p-type nitride semiconductor layer, and growing the semiconductor single crystal Removing the substrate from the n-type nitride semiconductor layer, etching the n-type nitride semiconductor layer exposed through the opening of the etch stop layer to form an uneven structure, and electrically connecting the n-type nitride semiconductor layer It provides a vertical structure semiconductor light emitting device manufacturing method comprising the step of forming an n-type electrode to The.

According to the present invention, in the formation of the uneven structure on the light emitting surface, it is possible to obtain a manufacturing method of the vertical structure semiconductor light emitting device which can easily control the size and shape without compromising the crystallinity of the semiconductor single crystal.

Description

Manufacturing method of vertical semiconductor light emitting device {MANUFACTURING METHOD OF VERTICAL SEMICONDUCTOR LIGHT EMITTING DEVICE}

The present invention relates to a method for manufacturing a vertical semiconductor light emitting device, and more particularly, to a method for manufacturing a vertical semiconductor light emitting device including forming a concave structure on a light emitting surface.

BACKGROUND A light emitting diode (LED) is a semiconductor device capable of generating light of various colors based on recombination of electrons and holes at a junction portion of a p and n type semiconductor when current is applied thereto. The demand for these LEDs continues to increase because of their advantages such as long life, low power, excellent initial drive characteristics, high vibration resistance, and high tolerance for repetitive power interruptions. In particular, in recent years, group III nitride semiconductors capable of emitting light in a blue short wavelength region have been in the spotlight.

The nitride single crystal constituting the light emitting device using the group III nitride semiconductor is formed on a specific single crystal growth substrate, such as a sapphire or SiC substrate. However, when an insulating substrate such as sapphire is used, the arrangement of the electrodes is greatly limited. That is, in the conventional nitride semiconductor light emitting device, since the electrodes are generally arranged in the horizontal direction, the current flow becomes narrow. Due to such a narrow current flow, the operating voltage (Vf) of the light emitting device is increased, the current efficiency is lowered, and at the same time, there is a problem of being vulnerable to electrostatic discharge. In order to solve this problem, a semiconductor light emitting device having a vertical structure is required.

In the case of the vertical semiconductor light emitting device, the light generated in the active layer has a different degree of reflection depending on the incident angle when incident on the air / GaN interface. In this case, theoretically, when the incident angle is 26 ° or more, all light generated in the active layer is totally internally reflected. Therefore, in order to minimize such a problem and improve the external light extraction efficiency, the concave-convex structure can be formed on the surface through which light is transmitted to the outside.

According to experimental results known in the art, light extraction efficiency is improved when there is an uneven pattern, and when the cross-section of the uneven structure is rectangular, but slightly triangular or trapezoidal, the light extraction efficiency is slightly higher. High is common. Further, the uneven structure may be more advantageous in improving light extraction efficiency as the size thereof is smaller (nano size).

On the other hand, in the vertical semiconductor light emitting device, reactive ion etching (RIE) or the like is generally applied to the n-type nitride semiconductor layer in order to form the uneven structure, but in this case, the region around the uneven structure suffers plasma damage, resulting in high light extraction efficiency. There is a problem of deterioration.

Therefore, in the art, it is required to develop a technology that can easily control the size and shape of the uneven structure without compromising the crystallinity of the semiconductor single crystal.

The present invention is to solve the above problems, an object of the present invention is to form an uneven structure on the light emitting surface, it is possible to easily control the size and shape of the semiconductor single crystal without compromising the crystallinity The present invention provides a method for manufacturing a vertical semiconductor light emitting device.

In order to achieve the above object, a preferred embodiment of the present invention,

Forming an etch stop layer having an opening on the semiconductor single crystal growth substrate, and forming an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer on the semiconductor single crystal growth substrate and the etch stop layer through the openings; Sequentially growing; forming a conductive substrate on the p-type nitride semiconductor layer; removing the semiconductor single crystal growth substrate from the n-type nitride semiconductor layer; and openings of the etch stop layer And forming an uneven structure by etching the exposed n-type nitride semiconductor layer and forming an n-type electrode to be electrically connected to the n-type nitride semiconductor layer.

Preferably, the step of forming the uneven structure by etching the n-type nitride semiconductor layer may be performed by wet etching, in this case, KOH solution may be used.

In particular, the region removed by wet etching in the n-type nitride semiconductor layer preferably has a pyramid shape. In addition, the n-type nitride semiconductor layer surface forming the uneven structure may be a (11-2-2) crystal surface.

In a preferred embodiment of the present invention, further comprising the step of growing an undoped nitride semiconductor layer on the semiconductor single crystal growth substrate before forming the etch stop layer, by etching the n-type nitride semiconductor layer uneven structure The step of forming may include removing the undoped nitride semiconductor layer.

The method may further include removing the etch stop layer after etching the n-type nitride semiconductor layer to form an uneven structure.

Preferably, the etch stop layer may include at least one material selected from the group consisting of metal oxides, silicon oxides and silicon nitrides.

In addition, the thickness of the etch stop layer is preferably 10 ~ 500nm.

The etch stop layer preferably has a lattice pattern structure. In this case, the lattice pattern forming the etch stop layer preferably has a diameter of 100 to 500 nm, and a period of the lattice pattern is 200 to 500 nm. .

On the other hand, between the step of growing the p-type nitride semiconductor layer and the step of forming the conductive substrate, forming a reflective metal layer to cover the upper surface and the side of the p-type nitride semiconductor layer. In this case, the reflective metal layer may include at least one material selected from the group consisting of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, and Au.

In addition, the removing of the semiconductor single crystal growth substrate may be performed by a laser lift-off process.

As described above, according to the present invention, in forming a concave-convex structure on the light emitting surface, a method of manufacturing a vertical structure semiconductor light emitting device which can easily control the size and shape of the semiconductor single crystal without harming the crystallinity. Can be obtained.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

1A to 1H are cross-sectional views illustrating processes for manufacturing a vertical structure semiconductor light emitting device according to one embodiment of the present invention.

First, as shown in FIG. 1A, an etch stop layer 12 is formed on the sapphire substrate 11.

The sapphire substrate 11 is a crystal having hexagonal-Rhombo R3c symmetry and has a lattice constant in the c-axis direction of 13.001Å and a lattice distance of 4.765Å in the a-axis, An orientation plane includes a C (0001) plane, an A (1120) plane, an R (1102) plane, and the like. The C surface of the sapphire substrate 11 is mainly used as a nitride growth substrate because it is relatively easy to grow a nitride thin film and stable at high temperatures. However, in the present invention, not only sapphire can be used as the single crystal growth substrate, but a substrate made of SiC, MgAl ₂ O ₄ , MgO, LiAlO ₂ , LiGaO _2, or the like may be employed.

The etch stop layer 12 formed on the sapphire substrate 11 has a pattern structure to have an opening that exposes a predetermined region of the upper surface of the sapphire substrate 11. As described below, the etch stop layer 12 may prevent some regions of the n-type nitride semiconductor layer from being etched so that the uneven structure becomes a desired shape in the wet etching process for forming the uneven structure in the n-type nitride semiconductor layer. To this end, the etch stop layer 12 is a material that is not etched in a wet etching solution (eg, KOH) is employed, specifically, a metal oxide, silicon oxide, silicon nitride, and the like can be used. When the etch stop layer 12 is formed of a metal oxide, it is preferable to use TCO, ZnO, or the like having both light transmittance and electrical conductivity. The height t of the etch stop layer 12 may be adjusted according to the size and shape of the desired concave-convex structure, but an appropriate height t is 10 to 500 nm.

Although not shown, the etch stop layer 12 may be formed using a method known in the art, for example, by photolithography, imprint, hollithography, or the like. After forming the mask, it may be formed using a method of removing the remaining regions except for the desired etch stop layer 12 pattern.

Next, as shown in FIG. 1B, the n-type nitride semiconductor layer 13 is grown through the sapphire substrate 11 exposed through the opening to cover the sapphire substrate 11 and the etch stop layer 12. Next, as shown in FIG. 1C, the active layer 14 and the p-type nitride semiconductor layer 15 are grown on the n-type nitride semiconductor layer 13.

The n-type and p-type nitride semiconductor layers 13 and 15 are Al _x In _y Ga _(1-xy) N composition formulas, where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ x + y ≦ 1. ), And may be formed of a semiconductor material doped with n-type impurities and p-type impurities, respectively. Representative examples thereof include GaN, AlGaN, and InGaN. In addition, Si, Ge, Se, Te or C may be used as the n-type impurity, and the p-type impurity may be representative of Mg, Zn or Be.

The active layer 14 is a layer in which light is generated by recombination of electrons and holes, and is composed of a nitride semiconductor layer having a single or multiple quantum well structure. The n-type nitride semiconductor layer, the active layer, and the p-type nitride semiconductor layer 13, 14, and 15 may be grown by organometallic vapor deposition (MOCVD), molecular beam growth (MBE), hybrid vapor deposition (HVPE), or the like. .

Subsequently, as illustrated in FIG. 1D, the conductive substrate 16 is formed on the p-type nitride semiconductor layer 15.

The conductive substrate 16 is an element included in the final vertical structure light emitting device, and serves as a support for supporting the light emitting structure together with the p-side electrode. In particular, when the sapphire substrate 11 is removed by a laser lift-off process to be described later, the light emitting structure having a relatively thin thickness can be more easily handled by the conductive substrate 16.

On the other hand, when the conductive substrate 16 is a metal, it is possible to perform plating, deposition, sputtering, or the like, but a plating process is preferable in terms of process efficiency. The plating process includes a known plating process used to form a metal layer, such as electroplating, non-plating, and deposition plating, and among these, it is preferable to use an electroplating method that requires a short plating time. However, the method of forming the conductive substrate in the present invention is not limited thereto, and the conductive substrate 16 may be bonded through wafer bonding.

Next, the sapphire substrate 11 is removed by a laser lift off (LLO) process. To this end, a laser beam is irradiated onto the lower surface of the sapphire substrate 11. In this case, the laser beam is preferably irradiated a plurality of times to each of the light emitting structures so that the laser beam can be separated into the size of the final light emitting device formed on the sapphire substrate 11 rather than being irradiated on the entire surface of the sapphire substrate 11.

Meanwhile, the step of removing the sapphire substrate 11 is preferably a laser lift-off process as in the present embodiment, but the present invention is not limited thereto, and may be removed through other mechanical or chemical processes. In FIG. 1E, the sapphire substrate is removed. As shown in FIG. 1E, the surface of the n-type nitride semiconductor layer 13 that is in contact with the sapphire substrate is exposed to the outside.

Next, as shown in FIG. 1F, the exposed surface of the n-type nitride semiconductor layer 13 is etched to form an uneven structure P. In the case of this embodiment, the uneven structure (P) may be formed using a wet etching, in detail, KOH solution. Accordingly, damage to the semiconductor single crystal in the region around the uneven structure can be minimized as compared with the case of using dry etching such as RIE. Furthermore, the etch stop layer 12 having a pattern structure can easily form a concave-convex structure of a desired shape. More details regarding the formation of the uneven structure will be described with reference to FIGS. 2, 3 and 4.

FIG. 2 is a plan view from above of an etch stop layer formed on a sapphire substrate, and FIG. 3 is a plan view showing an uneven structure formed by etching an n-type nitride semiconductor layer, and FIG. 4 is a distance between patterns of the etch stop layer. It is sectional drawing which shows the change of the uneven structure along.

2, in the present embodiment, the etch stop layer 12 has a lattice pattern structure, more specifically, a hexagonal lattice pattern structure, and a sapphire substrate in a region where the etch stop layer 12 is not formed. 11 is exposed to the outside. The pattern shape of the etch stop layer 12 may determine the shape and size of the uneven structure formed on the n-type nitride semiconductor layer. That is, the period s and the diameter d of the pattern determine the width and height of each of the uneven structure.

As shown in FIGS. 3 and 4, the uneven structure P formed in the n-type nitride semiconductor layer 13 is formed by removing regions between adjacent patterns of the etch stop layer 12. In addition, the removed region has a pyramid structure or similar shape, and the uneven structure P is formed along a hexagonal lattice pattern.

That is, when an etching solution such as a KOH solution or the like is applied to the exposed upper surface of the n-type nitride semiconductor layer 13, the n-type nitride semiconductor layer 13 may face a specific crystal plane, for example, a (11-2-2) plane. The uneven structure having can be formed. In this case, [-2] in the Miller index (11-2-2) indicates that a bar is attached over [2]. As such, the n-type nitride semiconductor layer 13 is removed by the etching solution until a specific crystal plane is exposed, and the shape and size of the uneven structure are easily controlled by appropriately adjusting the pattern structure of the etch stop layer 13. can do.

In this case, as shown in FIG. 4, as the distance between the etch stop layer 12 patterns increases, the height h of the uneven structure increases, and as described above, the etch stop layer 12 pattern structure is appropriately adjusted. Need to be. Taking the preferred form as an example, the diameter d of the etch stop layer 12 pattern is 100 to 500 nm, and the period s is 200 to 5000 nm. As described above, the uneven structure forming process proposed in the present embodiment can precisely control the desired uneven shape by appropriately arranging the size and spacing of the etch stop layer pattern, and further reduce the crystal damage of the n-type nitride semiconductor layer. Can be.

After the uneven structure is formed in the n-type nitride semiconductor layer, the etch stop layer is removed as shown in FIG. 1G, and then the n-type electrode 17 is formed in the uneven structure of the n-type nitride semiconductor layer 13 as shown in FIG. 1H. Form. The n-type electrode 17 may be formed by metal thin film deposition using APCVD, LPCVD, PECVD, or the like, and a material made of Ni / Au may be employed. The structure of the final device formed up to the n-type electrode is as shown in FIG. In some embodiments, the etch stop layer may be included in the final device without removing the etch stop layer.

5 and 6 are cross-sectional views illustrating a method of manufacturing a vertical structure semiconductor light emitting device according to an embodiment modified from the embodiment shown in FIG. 1.

First, in the embodiment shown in FIG. 5, the undoped nitride semiconductor layer 58 is grown on the upper surface of the sapphire substrate 51 before the etch stop layer 52 is formed. The undoped nitride semiconductor layer 58 may function as a buffer layer to improve crystal quality of the n-type nitride semiconductor layer 53, the active layer 54, and the p-type nitride semiconductor layer 55 sequentially grown thereon. It is removed in the etching process for forming the uneven structure.

Next, the embodiment shown in FIG. 6 further includes forming the reflective metal layer 69 on the p-type nitride semiconductor layer 65 prior to forming the conductive substrate 66. The reflective metal layer 69 has a function of reflecting light emitted from the active layer 64 toward the n-type nitride semiconductor layer 63 and the n-type electrode 67 in the vertical light emitting device, and the p-type nitride semiconductor layer 65. ) Can be used as an ohmic contact. Considering the reflection and ohmic contact function of the reflective metal layer 69, the reflective metal layer 69 includes materials such as Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, and the like. It can be done by. The reflective metal layer 69 may be formed by a deposition method or a sputtering process, which is a conventional metal layer forming method. However, the reflective metal layer 69 is employed to further improve the light extraction efficiency and is not an essential element in the present invention, and thus may not be employed in other embodiments.

The present invention is not limited by the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims. Accordingly, various forms of substitution, modification, and alteration may be made by those skilled in the art without departing from the technical spirit of the present invention described in the claims, which are also within the scope of the present invention. something to do.

1A to 1H are cross-sectional views illustrating processes for manufacturing a vertical structure semiconductor light emitting device according to one embodiment of the present invention.

FIG. 2 is a plan view from above of an etch stop layer formed on a sapphire substrate, and FIG. 3 is a plan view showing an uneven structure formed by etching an n-type nitride semiconductor layer, and FIG. It is sectional drawing which shows the change of uneven structure.

5 and 6 are cross-sectional views illustrating a method of manufacturing a vertical structure semiconductor light emitting device according to an embodiment modified from the embodiment shown in FIG. 1.

<Description of the symbols for the main parts of the drawings>

11: sapphire substrate 12: etch stop layer

13: n-type nitride semiconductor layer 14: active layer

15: p-type nitride semiconductor layer 16: conductive substrate

17: n-type electrode 58: undoped nitride semiconductor layer

69: reflective metal layer

Claims (15)

Forming an etch stop layer having an opening on the substrate for semiconductor single crystal growth; Sequentially growing an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer on the semiconductor single crystal growth substrate and the etch stop layer through the openings; Forming a conductive substrate on the p-type nitride semiconductor layer; Removing the semiconductor single crystal growth substrate from the n-type nitride semiconductor layer; Etching the n-type nitride semiconductor layer exposed through the opening of the etch stop layer to form an uneven structure; And And forming an n-type electrode to be electrically connected to the n-type nitride semiconductor layer. The method of claim 1, And etching the n-type nitride semiconductor layer to form the uneven structure by wet etching. The method of claim 2, The wet etching method of manufacturing a vertical semiconductor light emitting device, characterized in that performed using a KOH solution. The method of claim 2, And a region removed by wet etching in the n-type nitride semiconductor layer has a pyramid shape. The method of claim 4, wherein And the n-type nitride semiconductor layer surface forming the uneven structure is a (11-2-2) crystal surface. The method of claim 1, Further comprising growing an undoped nitride semiconductor layer on the semiconductor single crystal growth substrate before forming the etch stop layer. And etching the n-type nitride semiconductor layer to form the uneven structure includes removing the undoped nitride semiconductor layer. The method of claim 1, After the step of forming the uneven structure by etching the n-type nitride semiconductor layer, the step of removing the etch stop layer further comprises a vertical structure semiconductor light emitting device manufacturing method. The method of claim 1, And the etch stop layer comprises at least one material selected from the group consisting of metal oxides, silicon oxides and silicon nitrides. The method of claim 1, The thickness of the etch stop layer is a vertical semiconductor light emitting device manufacturing method, characterized in that 10 ~ 500nm. The method of claim 1, The etch stop layer has a lattice pattern structure, characterized in that the semiconductor light emitting device manufacturing method. The method of claim 10, The lattice pattern forming the etch stop layer has a diameter of each pattern 100 ~ 500nm characterized in that the manufacturing method of the vertical structure semiconductor light emitting device. The method of claim 10, The period of the lattice pattern constituting the etch stop layer is a method of manufacturing a vertical semiconductor light emitting device, characterized in that 200 ~ 5000nm. The method of claim 1, And forming a reflective metal layer covering the top and side surfaces of the p-type nitride semiconductor layer between the growing of the p-type nitride semiconductor layer and the forming of the conductive substrate. Semiconductor light emitting device manufacturing method. The method of claim 13, And the reflective metal layer comprises at least one material selected from the group consisting of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt and Au. The method of claim 1, Removing the semiconductor single crystal growth substrate is performed by a laser lift-off process.

Images