KR100982983B1 - Vertical semiconductor light emitting device and manufacturing method of the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical structure semiconductor light emitting device and a method of manufacturing the same. An aspect of the present invention relates to an n-type nitride semiconductor layer, an active layer formed to cover the top and side surfaces of the n-type nitride semiconductor layer, and the active layer. A vertical structure including a light emitting structure having a p-type nitride semiconductor layer formed to cover top and side surfaces, a conductive substrate formed on the p-type nitride semiconductor layer and an n-type electrode formed to be electrically connected to the n-type nitride semiconductor layer Provided is a semiconductor light emitting device.

According to the present invention, it is possible to obtain a vertical structure semiconductor light emitting device in which the crystal quality of the side surface is improved and the high luminous efficiency can be obtained by including an efficient reflective structure.

Light emitting element, LED, vertical structure, nitride, dielectric pattern

Description

Vertical structure semiconductor light emitting device and its manufacturing method {VERTICAL SEMICONDUCTOR LIGHT EMITTING DEVICE AND MANUFACTURING METHOD OF THE SAME}

The present invention relates to a vertical structure semiconductor light emitting device and a method of manufacturing the same, and more particularly to a vertical structure semiconductor light emitting device having improved luminous efficiency and to a method for manufacturing a vertical structure semiconductor light emitting device to enable the growth of a single device unit will be.

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 series 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, in the case of using an insulating substrate such as sapphire, the arrangement of 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 nitride semiconductor light emitting device having a vertical structure is required.

1 is a cross-sectional view showing a part of a manufacturing process of a vertical semiconductor light emitting device according to the prior art.

In the prior art, an n-type nitride semiconductor layer 12, an active layer 13, and a p-type nitride semiconductor layer 14 are sequentially grown on a sapphire substrate 11 serving as a semiconductor single crystal growth substrate to form a light emitting structure. Form. Thereafter, as shown in FIG. 1, the separation is performed in units of elements through dry wetness.

As described above, when dry wetting or the like is performed to separate the device units, side surfaces of each light emitting structure are damaged (for example, plasma damage), resulting in inferior crystallinity, and thus there is a problem in that luminous efficiency is lowered. .

Therefore, there is a need in the art for the development of a vertical semiconductor light emitting device in which the crystal quality of the side is high, and further, the light emitting efficiency can be improved by having an appropriate reflection structure.

The present invention is to solve the above problems, an object of the present invention is to provide a vertical structure semiconductor light emitting device that can improve the crystal quality of the side, and obtain a high luminous efficiency by including an efficient reflective structure have.

Furthermore, another object of the present invention is to provide a method for manufacturing a vertical semiconductor light emitting device which improves the crystal quality of the side surface and enables the growth of a single device unit.

In order to achieve the above object, one aspect of the present invention,

A light emitting structure comprising an n-type nitride semiconductor layer, an active layer formed to cover the top and side surfaces of the n-type nitride semiconductor layer, and a p-type nitride semiconductor layer formed to cover the top and side surfaces of the active layer, the p-type nitride semiconductor A vertical structure semiconductor light emitting device including a conductive substrate formed on a layer and an n-type electrode formed to be electrically connected to the n-type nitride semiconductor layer.

In a preferred embodiment of the present invention, the side surface of the light emitting structure may be an inclined surface having a predetermined slope with respect to the horizontal plane. In this case, the side surface of the light emitting structure is preferably a surface inclined toward the conductive substrate. More specifically, the side of the light emitting structure may have a slope with respect to the horizontal plane of 30 ° or more, less than 90 °.

The vertical semiconductor light emitting device according to the preferred embodiment of the present invention may further include a reflective metal layer formed to cover the top and side surfaces of the p-type nitride semiconductor layer between the p-type nitride semiconductor layer and the conductive substrate. 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.

The side surfaces of the light emitting structure and the reflective metal layer may be inclined surfaces having a predetermined slope with respect to a horizontal plane, and the side surfaces of the light emitting structure and the reflective metal layer are inclined surfaces toward the conductive substrate. Further, the light emitting structure and the side surfaces of the reflective metal layer have an inclination with respect to a horizontal plane of 30 ° or more, preferably less than 90 °.

According to another aspect of the present invention,

An n-type nitride semiconductor layer, an active layer and a p-type nitride semiconductor layer are sequentially grown on a substrate for semiconductor single crystal growth to form a light emitting structure. In the case of the active layer and the p-type nitride semiconductor layer, the n-type nitride semiconductor layer and Growing to cover the top and side surfaces of the active layer, 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 n It provides a vertical semiconductor light emitting device manufacturing method comprising the step of forming an n-type electrode to be electrically connected to the type nitride semiconductor layer.

In this case, the forming of the light emitting structure may be performed such that a side surface thereof has an inclined surface having a predetermined slope with respect to the growth surface of the substrate for growing a semiconductor single crystal. In addition, the step of forming the light emitting structure, may be performed so that the side has a surface inclined toward the growth direction, more specifically, it is preferable that the inclination is performed to be more than 30 °, less than 90 °.

According to another embodiment of the present invention,

Forming a dielectric pattern having a plurality of openings on the semiconductor single crystal growth substrate, and an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer on the semiconductor single crystal growth substrate exposed through the plurality of openings, respectively. Growing light sequentially to form a light emitting structure, and in the case of the active layer and the p-type nitride semiconductor layer, growing to cover the top and side surfaces of the n-type nitride semiconductor layer and the active layer, respectively, and the p-type nitride semiconductor layer Forming a conductive substrate on the substrate, removing the semiconductor single crystal growth substrate from the n-type nitride semiconductor layer, and forming an n-type electrode to be electrically connected to the plurality of n-type nitride semiconductor layers, respectively. And separating the plurality of light emitting structures into respective light emitting structures. It provides a method of manufacturing the light emitting device body.

Preferably, the method may further include forming a reflective metal layer covering the top and side surfaces of the p-type nitride semiconductor layer between growing the p-type nitride semiconductor layer and forming the conductive substrate. .

On the other hand, removing the semiconductor single crystal growth substrate may be performed by a laser lift off process.

Preferably, the height of the light emitting structure may be 3 ~ 15㎛.

In addition, the dielectric pattern is preferably a width of 50 ~ 200㎛.

In addition, the dielectric pattern may be formed of silicon oxide or silicon nitride.

Furthermore, the present invention may further include removing the dielectric pattern after removing the semiconductor single crystal growth substrate from the n-type nitride semiconductor layer.

As described above, according to the present invention, it is possible to obtain a vertical structure semiconductor light emitting device capable of improving the crystal quality of the side surface and obtaining a high luminous efficiency by including an efficient reflective structure.

Furthermore, according to the present invention, it is possible to obtain a vertical structure semiconductor light emitting device manufacturing method which improves the crystal quality of the side surface and enables the growth of a single device unit.

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.

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

2, the vertical nitride semiconductor light emitting device 20 according to the present embodiment includes an n-type nitride semiconductor layer 21, an active layer 22, a p-type nitride semiconductor layer 23, a reflective metal layer 24, The conductive substrate 26 and the n-type electrode 27 are provided. In this case, the dielectric pattern 25 shown in FIG. 2 is provided for device unit growth in the manufacturing process, and may be removed together with the sapphire substrate, which is a substrate for semiconductor single crystal growth, or may remain in the device as described below. However, it is not an essential component in this embodiment.

The n-type nitride semiconductor layer 21, the active layer 22, and the p-type nitride semiconductor layer 23 form a light emitting structure. As used herein, the term “light emitting structure” refers to a structure formed by sequentially stacking the n-type nitride semiconductor layer 21, the active layer 22, and the p-type nitride semiconductor layer 23.

The n-type and p-type nitride semiconductor layers 21 and 23 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 n-type and p-type nitride semiconductor layers 21 and 23 may be grown by organometallic vapor deposition (MOCVD), molecular beam growth (MBE), hybrid vapor deposition (HVPE), or the like.

The active layer 22 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. Like the n-type and p-type nitride semiconductor layers 21 and 23, the active layer may be grown by an organometallic vapor deposition method, a molecular beam growth method, a hybrid vapor deposition method, or the like.

On the other hand, in the present embodiment, the light emitting structure is not a structure laminated only on the upper surface of each semiconductor layer. That is, the active layer 22 is formed to cover both the top and side surfaces of the n-type nitride semiconductor layer 21, and in the same manner, the p-type nitride semiconductor layer 23 covers the top and side surfaces of the active layer 22. Is formed. Accordingly, the p-n junction diode structure is formed on the side of the light emitting structure, so that the light emitting area can be increased. Further, as will be described later, in the case of forming the reflective metal layer on the side to improve the luminous efficiency, in the prior art, an additional insulating layer is required so that the n-type nitride semiconductor layer and the p-type nitride semiconductor layer are not short-circuited with each other. Since the p-type nitride semiconductor layer 23 has a structure surrounding the n-type nitride semiconductor layer 21 as a whole, the reflective metal layer may be directly formed on the p-type nitride semiconductor layer 23.

In addition, the light emitting structure according to the present embodiment is an inclined surface whose side surface has a predetermined inclination with respect to the horizontal surface. As such, by forming the light emitting structure at an inclined side, the light emitting area can be increased by about 5%.

However, in the present invention, the side surface of the light emitting structure does not necessarily have to be an inclined surface, and may be formed perpendicular to the horizontal surface as shown in FIG. 3. 3 is a cross-sectional view illustrating a vertical structure semiconductor light emitting device according to an embodiment modified from the embodiment of FIG. 2, wherein the n-type nitride semiconductor layer 31, the active layer 32, the p-type nitride semiconductor layer 33, and the reflective metal layer are shown. 34, the conductive substrate 36, and the n-type electrode 37, and the dielectric pattern 35 may be removed or included as it is. Since the light emitting structure side surface is the same as the embodiment of FIG. 2 except that the side surface is perpendicular to the horizontal plane, detailed description of FIG. 3 will be omitted.

Referring back to the embodiment of FIG. 2, the reflective metal layer 24 formed on the p-type nitride semiconductor layer 23 directs the light emitted from the active layer 22 toward the n-type nitride semiconductor layer 21. It can perform the function of reflecting, and consists of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au and the like. In this case, although not shown in detail, the reflective metal layer 24 may have a structure of two or more layers to improve reflection efficiency. As a specific example, Ni / Ag, Zn / Ag, Ni / Al, Zn / Al, Pd / Ag, Pd / Al, Ir / Ag. Ir / Au, Pt / Ag, Pt / Al, Ni / Ag / Pt, etc. are mentioned.

The reflective metal layer 24 is similar to the shape of the active layer 22 and the p-type nitride semiconductor layer 23 to cover the top and side surfaces of the p-type nitride semiconductor layer 23, and the side surfaces thereof are inclined. As described above, the reflection efficiency can be greatly improved by adopting the reflective metal layer 24 having the inclined surface on the side while covering the side surface of the light emitting structure. However, since the reflective metal layer 24 is not an essential component in the present invention, it may be excluded depending on the embodiment.

The conductive substrate 26 serves as a support for supporting the light emitting structure together with the p-side electrode of the vertical semiconductor light emitting device 20. In this case, the conductive substrate 26 may be made of a material such as Si, Cu, Ni, Au, W, Ti, or the like. The n-type electrode 27 is made of a material such as Ni / Au, and can be formed by a known method such as APCVD, LPCVD, PECVD, and the like.

Hereinafter, the manufacturing process of the vertical structure semiconductor light emitting device having the above-described structure will be described. 4A to 4F are cross-sectional views of processes for describing a method of manufacturing the vertical semiconductor light emitting device of FIG. 2.

First, as shown in FIG. 4A, a dielectric pattern 45 is formed on the sapphire substrate 40.

The sapphire substrate 40 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 direction. 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 40 is relatively easy to grow a nitride thin film, and is mainly used as a nitride growth substrate because it is stable at high temperatures. However, not only the only thing that can be a sapphire substrate in the present invention as a substrate for growing a single crystal, SiC, MgAl ₂ O _4, MgO, LiAlO ₂ and LiGaO ₂ substrate also can be employed, such as made of.

The dielectric pattern 45 formed on the sapphire substrate 40 may be employed in a stripe structure or the like so as to have an opening O provided to the growth region of the light emitting device. That is, in the present embodiment, unlike the prior art, one vertical structure light emitting device may be formed in each opening O (chip-by-chip growth), and the distance between the dielectric patterns 45 adjacent to each other may vary with the size of the device. Substantially the same. In this case, in order for the light emitting structures grown in the respective openings O to be independent devices, adjacent ones should not be contacted during the growth of the semiconductor layer. To this end, the distance between the openings O, that is, the width of the dielectric pattern 45 should be ensured to some extent, and in view of the general light emitting structure having a height of 3 to 15㎛, the dielectric pattern 45 The width d of about 50-200 micrometers is preferable.

Although not shown, the dielectric pattern 45 may be formed by forming a dielectric layer covering the entire sapphire substrate 40 and then etching a region corresponding to the opening O using a mask. , Silicon oxide or silicon nitride.

As a next step, as shown in FIG. 4B, an n-type nitride semiconductor layer 41 is grown in each of the sapphire substrate 40 regions exposed by the opening.

In the case of this embodiment, the n-type nitride semiconductor layer 41 can be grown from the top surface of the sapphire substrate 40 through lateral growth, and in particular, the side surface thereof is grown to be an inclined surface. Accordingly, as described above, the effect of increasing the emission area can be expected. In this case, it is preferable that the angle θ formed between the side surface and the growth surface of the sapphire substrate 40 is 30 ° or more, which means that when the angle θ is too small, it is grown on the same sapphire substrate 40 surface. This is because the number of possible light emitting structures is reduced.

In addition, in order for the side surface of the n-type nitride semiconductor layer 41 to be an inclined surface, it is possible to increase the vertical growth rate compared to the horizontal growth rate, which is carried out through a known method such as controlling the injection of source gas Can be.

Next, as shown in FIG. 4C, the active layer 42 and the p-type nitride semiconductor layer 43 are sequentially grown to cover the top and side surfaces of the n-type nitride semiconductor layer 41. The growth process of the active layer 42 and the p-type nitride semiconductor layer 43 may be performed in the same manner as the growth process of the n-type nitride semiconductor layer 41. In this case, the n-type nitride semiconductor layer 41, the active layer 42, and the p-type nitride semiconductor layer 43 may be grown through processes such as organometallic vapor deposition, molecular beam growth, and hybrid vapor deposition.

Subsequently, as shown in FIG. 4D, the reflective metal layer 44 is formed to cover the top and side surfaces of the p-type nitride semiconductor layer 43, but the side surfaces thereof are inclined similarly to the side surfaces of the p-type nitride semiconductor layer 43. The reflective metal layer 44 may be formed by a deposition method or a sputtering process, which is a conventional metal layer forming method.

Subsequently, as shown in FIG. 4E, the conductive substrate 46 is formed on the reflective metal layer 44.

The conductive substrate 46 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 40 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 46.

In the case where the conductive substrate 46 is made of metal, plating, vapor deposition, sputtering, or the like may be performed. However, a plating process is preferable in terms of process efficiency. The plating process includes a known plating process used to form metal layers 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 46 may be bonded to the reflective metal layer 44 through wafer bonding.

Next, the sapphire substrate 40 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 40. 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 40 rather than being irradiated on the entire surface of the sapphire substrate 40.

On the other hand, the step of removing the sapphire substrate 40 is preferably a laser lift-off process as in this embodiment, the present invention is not limited thereto, and can be removed through other mechanical or chemical processes. 4F illustrates a state in which the sapphire substrate is removed.

Next, an n-type electrode (shown as 37 in FIG. 2) is formed on the surface from which the sapphire substrate is removed from the n-type nitride semiconductor layer 41, and then separated into individual light emitting structure units by a process such as dicing. In this case, the n-type electrode forming step and the dicing step may be reversed. The n-type electrode 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.

Meanwhile, in the above description, the manufacturing of each device by forming a plurality of light emitting structures by using a dielectric pattern and cutting the same has been described. However, the present invention is not limited thereto, and only one device may be formed without a cutting process. It will be possible. Further, although not particularly shown, irregularities may be formed on the light exit surface of the n-type nitride semiconductor layer in order to improve light extraction efficiency.

The present invention is not limited by the above-described embodiments and the accompanying drawings, but is intended to be limited only by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

1 is a cross-sectional view showing a part of a manufacturing process of a vertical semiconductor light emitting device according to the prior art.

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

3 is a cross-sectional view illustrating a vertical structure semiconductor light emitting device according to an embodiment modified from the embodiment of FIG. 2.

4A through 4F are cross-sectional views illustrating processes for manufacturing the vertical semiconductor light emitting device of FIG. 2.

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

21: n-type nitride semiconductor layer 22: active layer

23: p-type nitride semiconductor layer 24: reflective metal layer

25 dielectric pattern 26 conductive substrate

27: n-type electrode 40: sapphire substrate

Claims (21)

delete delete delete delete delete delete delete delete delete delete delete delete delete Forming a dielectric pattern having a plurality of openings on the semiconductor single crystal growth substrate; An n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer are sequentially grown on the semiconductor single crystal growth substrate exposed through the plurality of openings, respectively, to form a light emitting structure, wherein the active layer and the p-type nitride semiconductor layer In this case, the step of growing to cover the top and side surfaces of the n-type nitride semiconductor layer and the active layer, respectively; Forming a reflective metal layer to cover both the exposed top and side surfaces of the p-type nitride semiconductor layer; Forming a conductive substrate on the reflective metal layer; Removing the semiconductor single crystal growth substrate from the n-type nitride semiconductor layer; Forming an n-type electrode opposite the conductive substrate with the light emitting structure interposed therebetween to be electrically connected to the plurality of n-type nitride semiconductor layers, respectively; And And separating the plurality of light emitting structures into units of respective light emitting structures. delete The method of claim 14, 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 14, Removing the semiconductor single crystal growth substrate is performed by a laser lift-off process. The method of claim 14, The height of the light emitting structure is a vertical structure semiconductor light emitting device manufacturing method characterized in that 3 ~ 15㎛. The method of claim 14, The dielectric pattern has a width of 50 ~ 200㎛ vertical manufacturing method of the semiconductor light emitting device. The method of claim 14, The dielectric pattern is a method of manufacturing a vertical semiconductor light emitting device, characterized in that consisting of silicon oxide or silicon nitride. The method of claim 14, And removing the dielectric pattern after removing the semiconductor single crystal growth substrate from the n-type nitride semiconductor layer.

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