KR20050096741A - Method of producing nitride singl crystal, nitride semiconductor light emitting diode and method of producing the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride single crystal manufacturing method and a nitride semiconductor light emitting device, comprising: a substrate, a first buffer layer made of ZnO formed on the substrate, and an Al _x Ga _y In _z Ti _{1- (x} formed on the first buffer layer _{+ y + z)} a second buffer layer consisting of N (0 ≦ x, y, z ≦ 1, 0 <x + y + z <1), a first conductivity type nitride semiconductor layer formed on the second buffer layer, An active layer formed on the first conductivity type nitride semiconductor layer, a second conductivity type nitride semiconductor layer formed on the active layer, and first and second electrodes electrically connected to the first and second conductivity type nitride semiconductor layers, respectively. It provides a nitride semiconductor light emitting device comprising a.

Since the additional buffer layer according to the present invention provides growth conditions for nitride single crystals while preventing thermal decomposition of the ZnO buffer layer, not only a high quality nitride single crystal or nitride semiconductor light emitting device can be manufactured, but also has its own electrical conductivity, The current spreading effect is greatly improved and various structures (eg, vertical light emitting devices) can be easily changed.

Description

Nitride single crystal manufacturing method, nitride semiconductor light emitting device and manufacturing method {METHOD OF PRODUCING NITRIDE SINGL CRYSTAL, NITRIDE SEMICONDUCTOR LIGHT EMITTING DIODE AND METHOD OF PRODUCING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride semiconductor light emitting device, and more particularly, to a nitride single crystal manufacturing method using a novel buffer layer capable of compensating a weak ZnO buffer layer at a high temperature, a nitride semiconductor light emitting device and a manufacturing method using the same.

In general, nitride semiconductor single crystals have the advantage of being able to produce short wavelength light in the blue or ultraviolet region as well as in the visible range, for example, in the case of In _x Ga _1-x N compound semiconductor, According to the determination, since the energy band gap varies in a wide range, it shows a change in emission band from blue violet to red. Therefore, the nitride semiconductor is in the spotlight as a light emitting device such as a light emitting diode (LED) or a laser diode (LED) for full color.

In order to manufacture a more efficient optical device, such a nitride semiconductor single crystal requires a technology for growing into a high quality single crystal thin film. However, since nitride semiconductors are not universally suitable for their lattice constants and coefficients of thermal expansion, many constraints arise in growing single crystal thin films.

In general, a limited heterogeneous substrate, such as a sapphire (Al ₂ O ₃ ) substrate or a silicon carbide (SiC) substrate, is used as the substrate for nitride semiconductor crystal growth. The nitride semiconductor single crystal may be grown on the hetero substrate through a hetero-epitaxy growth method using organometallic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE).

However, even when the limited heterogeneous substrate is used, it is difficult to grow a high quality nitride semiconductor single crystal due to the mismatch of lattice constant and thermal expansion coefficient. For example, a sapphire substrate has a lattice constant difference of 16% and a thermal expansion coefficient difference of about 35% with GaN. Therefore, strain due to strain is generated between the interfaces, it is difficult to expect the growth of high quality nitride single crystal. In addition, the SiC substrate has a smaller lattice constant and thermal expansion coefficient difference than the sapphire substrate, but it is difficult to expect high-quality single crystal growth because unwanted micropipes are generated in the grown GaN layer.

In order to solve this problem, a method of providing an additional buffer layer on the hetero substrate is used. As a conventional buffer layer, a low temperature nucleation layer made of Al _x Ga _1-x N (0 <x <1) and a layer such as ZnO are used. 1 is a side sectional view showing a conventional nitride semiconductor light emitting device.

As shown in FIG. 1, the conventional nitride semiconductor light emitting device 10 includes an n-type nitride semiconductor layer 15, an active layer 16, and a p-type nitride semiconductor layer 17 on a sapphire substrate 11. . An n-side electrode 19a is formed in the region of the n-type nitride semiconductor layer 15 exposed by removing portions of the p-type nitride semiconductor layer 17 and the active layer 16 and the p-type GaN semiconductor layer 17 ), A transparent electrode 18 including Ni and Au and a p-side electrode 19b are formed.

In addition, the conventional nitride semiconductor light emitting device 10 includes a buffer layer 12 formed on the sapphire substrate 11. The buffer layer is a layer for forming a high quality single crystal, and the buffer layer 12 may be a low temperature nucleation layer or ZnO layer of Al _x Ga _1-x N (0 <x <1).

In particular, since the ZnO buffer layer can be acid etched using aqua regia or the like, it can be advantageously employed when separation of the sapphire substrate is required. For example, the ZnO layer may be used as a useful buffer layer in a nitride single crystal substrate manufacturing process or a vertical structure light emitting device manufacturing process.

However, despite the inherent advantages of the ZnO buffer layer, there is a fatal problem in that the surface of the ZnO buffer layer is seriously deteriorated due to severe redevaporation of Zn above 1000 ° C., which is the growth temperature of the nitride single crystal. Due to such thermal instability, there is a problem in that the nitride semiconductor layer grown in a subsequent process is inferior in adhesion with the ZnO layer and floats or even unintentionally leaves.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to provide a method for producing a nitride single crystal which forms an additional buffer layer that can solve the thermal instability of the ZnO buffer layer.

Another object of the present invention is to provide a method for preparing a nitride single crystal to form an additional buffer layer that can solve the thermal instability of the ZnO buffer layer.

In order to achieve the above technical problem, the present invention

Forming a first buffer layer of ZnO on a substrate, and Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 on the first buffer layer It provides a method for producing a nitride single crystal comprising the step of forming a second buffer layer consisting of <x + y + z <1), and forming a nitride single crystal on the second buffer layer.

Preferably, the method further comprises etching the first buffer layer to separate the nitride single crystal layer including the second buffer layer from the substrate, thereby obtaining a nitride single crystal layer usable as a nitride single crystal substrate.

According to another aspect of the present invention, there is provided a substrate, a first buffer layer formed of ZnO formed on the substrate, and Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0≤ ₎ formed on the first buffer layer. a second buffer layer consisting of x, y, z ≦ 1, 0 <x + y + z <1), a first conductivity type nitride semiconductor layer formed on the second buffer layer, and on the first conductivity type nitride semiconductor layer Provided are a nitride semiconductor light emitting device comprising an active layer formed on the substrate, a second conductive nitride semiconductor layer formed on the active layer, and first and second electrodes electrically connected to the first and second conductive semiconductor layers, respectively. .

Since the second buffer layer used in the present invention is a conductive layer having electrical conductivity, preferably, the first electrode has an upper surface of the second buffer layer exposed by removing portions of the first and second conductive semiconductor layers and the active layer. Can be formed on.

The first conductive semiconductor layer may be a p-type nitride semiconductor layer, and the second conductive semiconductor layer may be an n-type nitride semiconductor layer, and in this embodiment, an n-type nitride semiconductor layer having relatively low electrical resistance is mainly used. Since it is provided in the light emitting portion (upper), there is an advantage that it is not necessary to employ a transparent electrode having a low transmittance.

In order for the second buffer layer to have sufficient electrical conductivity without causing other property deterioration, the Ti content of the second buffer layer is preferably in the range of 0.001 to 0.5, and the thickness of the second buffer layer is at least 0.001 μm. It is desirable to.

Furthermore, the present invention provides a nitride semiconductor light emitting device having a new vertical structure. The light emitting device includes a conductive layer made of Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 <x + y + z <1), and A first conductive nitride semiconductor layer formed on the conductive layer, an active layer formed on the first conductive nitride semiconductor layer, a second conductive nitride semiconductor layer formed on the active layer, a lower surface of the conductive layer and the second And first and second electrodes respectively formed on the upper surface of the conductive nitride semiconductor layer.

Furthermore, the present invention provides a method of manufacturing a novel nitride semiconductor light emitting device. The method comprises forming a first buffer layer of ZnO on a substrate, and Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z on the first buffer layer _). Forming a second buffer layer consisting of ≦ 1, 0 <x + y + z <1), forming a first conductivity type nitride semiconductor layer on the second buffer layer, and forming the first conductivity type nitride semiconductor Forming an active layer on the layer, forming a second conductive nitride semiconductor layer on the active layer, and forming first and second electrodes electrically connected to the first and second conductive semiconductor layers, respectively. It includes a step.

In one embodiment of the method according to the present invention, the forming of the first electrode may include removing portions of the first and second conductivity-type semiconductor layers and portions of the active layer to expose a portion of the second buffer layer. And forming the first electrode on the exposed upper surface of the second buffer layer.

Further, in another embodiment of the method according to the present invention, after forming the second conductivity type nitride semiconductor layer, removing the substrate by etching the first buffer layer so that the bottom surface of the second buffer layer is exposed. The method may further include forming the first and second electrodes, and forming the first and second electrodes on the bottom surface of the second buffer layer and the top surface of the second conductivity type nitride semiconductor layer, respectively. By implementing the light emitting device having a vertical structure can be provided.

In the present invention, Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 <x + y + z <1) material (hereinafter, Ti (Al, Ga) (Indicated by In) N) to provide an additional buffer layer. A Ti (Al, Ga, In) N buffer layer is additionally provided on top of the ZnO buffer layer to control other Al, Ga, In compositions along with Ti to serve as an excellent buffer layer with small lattice constants and thermal expansion coefficients, and at high temperatures during nitride growth. It can serve as a protective layer for the ZnO buffer layer due to thermal decomposition and a buffer layer for the ZnO defect occurrence surface.

In addition, since the Ti (Al, Ga, In) N buffer layer includes Ti composition and has electric conductivity itself, there is an advantage in that the light emitting device can be easily changed to have better efficiency. Typically, the n-type nitride semiconductor layer is easily implemented as a light emitting device and / or a vertical structure light emitting device disposed on the active layer, it can be expected to further excellent effect.

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

2A through 2D are cross-sectional views illustrating a method of manufacturing a nitride single crystal according to the present invention.

First, as shown in FIG. 2A, a first buffer layer 22 made of ZnO is formed on the substrate 21. The substrate 21 may be a substrate commonly used to grow nitride semiconductor crystals. For example, the substrate 21 may be a sapphire substrate or a SiC substrate. Since ZnO used as the first buffer layer 22 in the present invention has low thermal stability, there is a problem that the Zn component is evaporated at the nitride growth temperature (1000 ° C.) to cause surface defects. Thus, the present invention provides an additional second buffer layer.

Referring to FIG. 2B, Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 <x + y + formed on the first buffer layer 22). A second buffer layer 24 composed of z <1 is shown. The Ti (Al, Ga, In) N material used as the second buffer layer 24 may be expected to mitigate lattice matching and thermal expansion coefficient difference better than ZnO by controlling the composition of Ti and the like. In addition, the ZnO buffer layer 22 described above serves as a protective layer to prevent thermal decomposition easily in a high temperature environment.

2C, a nitride single crystal layer 25 is formed on the second buffer layer 24. The nitride single crystal layer 25 may be formed by a hetero-epitaxial growth method such as MOCVD, MBE, HPVE process. The nitride single crystal layer 25 may be an Al _x Ga _y In _z N (0 ≦ x, y, _z ≦ 1, x + y + z = 1) crystal layer, or a GaN layer for manufacturing a GaN single crystal substrate. . As such, since the nitride single crystal layer 25 formed on the second buffer layer 24 is formed on the second buffer layer 24 having additionally relaxed growth conditions, the nitride single crystal of higher quality may be manufactured.

Next, as shown in FIG. 2D, the first buffer layer 22 may be additionally etched to separate the nitride single crystal layer 25 including the second buffer layer 24 from the substrate 21. The first buffer layer 22, which is ZnO, can be easily removed using a suitable known etching solution such as aqua regia. As a result, a nitride (Ti (Al, Ga, In) N layer, which is a second buffer layer 24, is provided on the lower surface thereof. Single crystal substrates may be provided. Although a portion of ZnO 22 'may remain in this process, at least ZnO remaining on the second buffer layer 24 is preferably removed. In addition, since the Ti (Al, Ga, In) N layer 24 is an electrically conductive layer, the Ti (Al, Ga, In) N layer 24 may be preferably applied in the manufacture of various electrical devices such as light emitting devices even if they are not removed. More specifically, when the conductivity is increased by controlling the Ti component and the layer thickness, the contact resistance is improved, and thus it may be used more advantageously than the pure nitride single crystal layer.

3 is a side cross-sectional view of the nitride semiconductor light emitting device 30 according to the embodiment of the present invention.

The nitride semiconductor light emitting device 30 according to the present embodiment includes first and second buffer layers 32 and 34 formed on the substrate 31, and an n-type nitride semiconductor layer on the second buffer layer 34. 35, the active layer 36 and the p-type nitride semiconductor layer 37 have a structure formed sequentially. The substrate 31 may be a conventional substrate such as a sapphire substrate or a SiC substrate, and the p-type and n-type nitride semiconductor layers 35 and 37 may be p-type and n-type AlGaInN layers, respectively. In addition, the active layer 36 may have a multi-quantum well structure and may include a plurality of InGaN / GaN layers. The n-side electrode 39a is formed on the n-type nitride semiconductor layer 35 exposed by removing partial regions of the p-type nitride semiconductor layer 37 and the active layer 36, and the p-side electrode 39b is p It may be formed on a transparent electrode 38, such as a Ni / Au layer formed on the type nitride semiconductor layer 37.

The first buffer layer 32 formed on the substrate 31 is made of ZnO, and the second buffer layer 34 formed on the first buffer layer 32 is made of Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 <x + y + z <1). The Ti (Al, Ga, In) N layer employed as the second buffer layer 34 serves as an excellent buffer having a small lattice constant and a coefficient of thermal expansion by controlling another Al, Ga, In composition together with Ti, and further, a nitride single crystal. Can act as a protective layer for the ZnO buffer layer due to thermal decomposition at high temperatures during growth and as an additional quality buffer layer for ZnO defects

4 is a side cross-sectional view of the nitride semiconductor light emitting device 40 according to another embodiment of the present invention.

The nitride semiconductor light emitting device 40 according to the present embodiment includes first and second buffer layers 42 and 44 formed on the substrate 41, and a p-type nitride semiconductor layer on the second buffer layer 44. 47, the active layer 46 and the n-type nitride semiconductor layer 45 have a structure formed sequentially. Similar to the embodiment shown in FIG. 3, the substrate 41 may be a sapphire substrate or a SiC substrate, and the p-type and n-type nitride semiconductor layers 47 and 45 may be AlGaInN layers. In addition, the active layer 46 may be composed of a plurality of InGaN / GaN layers having a multi-quantum well structure.

However, in this embodiment, unlike the embodiment shown in FIG. 3, the n-type nitride semiconductor layer 45 is formed on the active layer 46. In addition, the n-side electrode 49a is formed in the n-type conductive semiconductor layer 45, and the p-side electrode 49b is formed of the p-type and n-type nitride semiconductor layers 47 and 45 and the active layer 46. The partial region is removed and is formed on the exposed second buffer layer 44.

The second buffer layer 44 formed on the first buffer layer 42 which is a ZnO material is Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 <x + y + z <1). Similarly to the embodiment shown in FIG. 2, the second buffer layer 44 serves to protect the first buffer layer 42, which is ZnO, with an additional buffer role, and contains Ti, and thus has electrical conductivity. In addition, the conductive layer function is also performed. Accordingly, the p-side electrode 49b may electrically connect the second buffer layer 44, which is a conductive layer, to the p-type nitride semiconductor layer 47.

Like the second buffer layer 44 of the present embodiment, in order to effectively perform the conductive layer function, it is preferable to appropriately limit the content of Ti composition and / or the layer thickness t.

More specifically, the second buffer layer 44 as the conductive layer preferably has a Ti content in the range of 0.001 to 0.5. If the Ti content is less than 0.001, it is difficult to have sufficient conductivity. If the Ti content is more than 0.5, crystallinity becomes a problem and it is difficult to sufficiently perform the buffer role. The second buffer layer 44 preferably has a thickness t in the range of 0.001 μm. When the thickness t of the second buffer layer is less than 0.001, it is difficult to expect sufficient buffer and protective layer roles. However, in consideration of thin film growth time and characteristics, the thickness of the second buffer layer 44 may not exceed 500 μm.

In addition, the second buffer layer 44 having Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 <x + y + z <1) has an upper roll. Increasingly, it is desirable that the x, y, z, which determines the mixing ratio, gradually increase. As x, y, and z gradually increase, near-surface of the second buffer layer 44 is formed of (Al) Ga (In) N having almost the same lattice constant as GaN, so that subsequent crystal growth may be advantageous. .

As such, in the present embodiment, the second buffer layer 44 can be used as a contact resistance improvement layer for the p-side electrode 49b. Therefore, since the current diffusion efficiency from the p-side electrode 49b can be greatly improved, the area S of the mesa etching portion for forming the p-side electrode 49b can be reduced as compared with the conventional light emitting device under the same conditions. In addition, since the active layer removal area is reduced, the effective light emitting area can be increased to greatly improve the overall luminous efficiency.

In addition, whether or not the second buffer layer 44 is employed as a contact resistance improvement layer may be considered in a structure in which the p-type nitride semiconductor layer 37 is disposed on the upper portion. That is, by removing the p-type and n-type nitride semiconductor layers 37 and 35 and the active layer 36 in a structure similar to that of FIG. 3, and forming the n-side electrode 39a on the second buffer layer 34, In principle, the current diffusion efficiency and the luminous efficiency thereof can be greatly improved.

5A to 5E are cross-sectional views illustrating a method of manufacturing a nitride semiconductor light emitting device according to still another embodiment of the present invention.

First, as shown in FIG. 5A, a first buffer layer 52 made of ZnO is formed on the substrate 51. The substrate 51 may be a substrate commonly used to grow nitride semiconductor crystals. For example, the substrate may be a sapphire substrate or a SiC substrate.

5B, Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 <x + y +) is formed on the first buffer layer 52. A second buffer layer 54 made of z <1 is formed. The Ti (Al, Ga, In) N material used as the second buffer layer 54 may be expected to further mitigate the lattice matching and thermal expansion coefficient difference superior to ZnO by controlling the composition of Ti and the like. In addition, the first buffer layer, which is ZnO, may act as a protective layer so that thermal decomposition is not easily performed even in a high temperature environment.

Next, a first conductivity type nitride semiconductor layer 55, an active layer 56, and a second conductivity type nitride semiconductor layer 57 are sequentially formed on the second buffer layer 54. The first and second conductivity type nitride semiconductor layers 55 and 57 and the active layer 56 may be formed by a hetero-epitaxial growth method such as a MOCVD, MBE, and HPVE process. The nitride single crystal layers 55, 56, and 57 formed on the second buffer layer 54 may be made of higher quality nitride single crystals under improved growth conditions (lattice matching and thermal expansion coefficient difference) than those of the first buffer layer 52. .

Next, as illustrated in FIG. 5D, the first buffer layer 52 is etched to expose the bottom surface of the second buffer layer 54. In the present etching process, the first buffer layer 52, which is ZnO, is removed (at least partially removed), so that the substrate 51 can be removed, and when the portion of ZnO 52 'remains, it can be removed with it. have. The etching of the first buffer layer 52, which is a ZnO material, may be performed using a known etchant such as aqua regia.

Next, as shown in FIG. 5E, the first and second electrodes 59a and 59b are formed on the bottom surface of the second buffer layer 54 and the top surface of the second conductivity type nitride semiconductor layer 57, respectively. As described above, in order to effectively perform the function of the conductive layer, the second buffer layer 54 may be formed by appropriately limiting the Ti composition and / or the layer thickness t in FIG. 2D. More specifically, the second buffer layer 54 as the conductive layer preferably has a Ti content in the range of 0.001 to 0.5, and preferably has a thickness of at least 0.001 µm.

5A to 5E, the manufacturing method of the vertical structure light emitting device has been described. However, similar to the above process, the manufacturing method of the horizontal structure light emitting device having the lateral current flow as shown in FIG. 3 or 4 can be provided.

In another embodiment of the present invention, in the method of manufacturing the horizontal structure light emitting device, after the nitride single crystal layers 55, 56, 57 are grown in a manner similar to FIGS. 5A to 5C, a part of the upper surface of the second buffer layer 54 is formed. The second conductive nitride semiconductor layer 57 and a partial region of the active layer 56 (the first electrode 59a is formed on the second buffer layer 54 so as to expose the first conductive semiconductor layer). A portion of the first semiconductor layer 55 is removed, and first and second layers are formed on the first conductive nitride semiconductor layer 55 (or the second buffer layer 54) and the second conductive nitride semiconductor layer 57. It can also be implemented by a method of forming the two electrodes (59a, 59b) respectively.

As such, the invention is not limited by the embodiments described above and the accompanying drawings, but rather by the appended claims. Therefore, it will be apparent to those skilled in the art that various forms of substitution, modification, and alteration are possible without departing from the technical spirit of the present invention described in the claims.

As described above, according to the present invention, Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 <x + y + z < ₎ on the ZnO buffer layer. 1) By forming an additional buffer layer with the material, it is possible to provide growth conditions for the nitride single crystal while preventing thermal decomposition of the ZnO buffer layer. Therefore, a high quality nitride single crystal or nitride semiconductor light emitting device can be manufactured, and furthermore, since the buffer layer according to the present invention including Ti composition has its own electrical conductivity, the current diffusion effect can be greatly improved and various structures (eg, vertical structures) The light emitting device provides an advantage that it is easy to change.

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

2A through 2D are cross-sectional views illustrating a method of manufacturing a nitride single crystal according to the present invention.

3 is a side cross-sectional view of a nitride semiconductor light emitting device according to one embodiment of the present invention.

4 is a side cross-sectional view of a nitride semiconductor light emitting device according to another embodiment of the present invention.

5A to 5E are cross-sectional views illustrating a method of manufacturing a nitride semiconductor light emitting device according to still another embodiment of the present invention.

<Code Description of Main Parts of Drawing>

31,41,51: substrate

32, 42, 52: ZnO buffer layer (or first buffer layer)

34,44,54: Ti (Al, Ga, In) N buffer layer (or second buffer layer)

35,45,55: n-type nitride semiconductor layer 36,46,56: active layer

37, 47, 57: p-type nitride semiconductor layer 39a, 49a, 59a: n-side electrode

39b, 49b, 59b: p-side electrode

Claims (16)

Forming a first buffer layer of ZnO on the substrate; A second buffer layer including Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 <x + y + z <1) is formed on the first buffer layer. Forming; And, Forming a nitride single crystal layer on the second buffer layer. The method of claim 1, Etching the first buffer layer to separate the nitride single crystal layer including the second buffer layer from the substrate. Board; A first buffer layer made of ZnO formed on the substrate; A second buffer layer made of Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 <x + y + z <1) formed on the first buffer layer ; A first conductivity type nitride semiconductor layer formed on the second buffer layer; An active layer formed on the first conductivity type nitride semiconductor layer; A second conductivity type nitride semiconductor layer formed on the active layer; And, And a first electrode and a second electrode electrically connected to the first and second conductivity type nitride semiconductor layers, respectively. The method of claim 3, The first electrode may include a second exposed second portion of the first and second conductivity type nitride semiconductor layers and the active layer removed to be electrically connected to the first conductivity type nitride semiconductor layer through the second buffer layer. A nitride semiconductor light emitting device, characterized in that formed on the buffer layer upper surface. The method of claim 4, wherein And the first conductivity type nitride semiconductor layer is a p-type nitride semiconductor layer, and the second conductivity type nitride semiconductor layer is an n-type nitride semiconductor layer. The method of claim 4, wherein The Ti content of the second buffer layer is a nitride semiconductor light emitting device, characterized in that 0.001 to 0.5. The method of claim 4, wherein The thickness of the second buffer layer is a nitride semiconductor light emitting device, characterized in that at least 0.001㎛. A conductive layer made of Al _x Ga _y In _z Ti _{1-(x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 <x + y + z <1); A first conductivity type nitride semiconductor layer formed on the conductive layer; An active layer formed on the first conductivity type nitride semiconductor layer; A second conductivity type nitride semiconductor layer formed on the active layer; And, And a first electrode and a second electrode formed on the lower surface of the conductive layer and the upper surface of the second conductive nitride semiconductor layer, respectively. The method of claim 8, The Ti content of the second buffer layer is a nitride semiconductor light emitting device, characterized in that 0.001 to 0.5. The method of claim 8, The thickness of the second buffer layer is a nitride semiconductor light emitting device, characterized in that at least 0.001㎛. Forming a first buffer layer of ZnO on the substrate; A second buffer layer including Al _x Ga _y In _z Ti _{1- (x + y + z)} N (0 ≦ x, y, z ≦ 1, 0 <x + y + z <1) is formed on the first buffer layer. Forming; Forming a first conductivity type nitride semiconductor layer on the second buffer layer; Forming an active layer on the first conductivity type nitride semiconductor layer; Forming a second conductivity type nitride semiconductor layer on the active layer; And And forming first and second electrodes electrically connected to the first and second conductivity type nitride semiconductor layers, respectively. The method of claim 11, Forming the first electrode, Removing partial regions of the first and second conductivity-type semiconductor layers and the active layer to expose a portion of the second buffer layer; And forming the first electrode on an exposed top surface of the second buffer layer to be electrically connected to the first conductivity type semiconductor layer through the second buffer layer. The method of claim 12, And the first conductivity type nitride semiconductor layer is a p-type nitride semiconductor layer, and the second conductivity type nitride semiconductor layer is an n-type nitride semiconductor layer. The method of claim 11, After forming the second conductivity type nitride semiconductor layer, removing the substrate by etching the first buffer layer to expose the bottom surface of the second buffer layer, The forming of the first and second electrodes may include forming the first and second electrodes on the bottom surface of the second buffer layer and the top surface of the second conductivity type nitride semiconductor layer, respectively. Device manufacturing method. The method according to claim 12 or 14, wherein The Ti content of the second buffer layer is a method for manufacturing a nitride semiconductor light emitting device, characterized in that 0.001 to 0.5. The method according to claim 12 or 14, wherein The thickness of the second buffer layer is at least 0.001㎛ manufacturing method of the nitride semiconductor light emitting device.