KR100990645B1 - Manufacturing method of nitride single crystal and manufacturing method of semiconductor light emitting devide using the same - Google Patents

Abstract

The present invention relates to a method of manufacturing a nitride single crystal having a high crystalline and a method of manufacturing a semiconductor light emitting device using the same, characterized in that to form a nitride single crystal seed on the sacrificial layer, and to grow a nitride single crystal around the nitride single crystal seed It is done. As a result, it is possible to grow a high crystalline nitride single crystal and to use a wet etching method when removing the growth substrate, thereby manufacturing a semiconductor light emitting device having excellent luminous efficiency.

Nitride single crystal seed, sacrificial layer, wet etching, semiconductor light emitting device.

Description

Manufacturing method of nitride single crystal and manufacturing method of semiconductor light emitting device using same {Manufacturing method of nitride single crystal and manufacturing method of semiconductor light emitting devide using the same}

The present invention relates to a method for manufacturing a nitride single crystal and a method for manufacturing a semiconductor light emitting device using the same, and more particularly to a method for manufacturing a nitride single crystal having a high crystal formed on the sacrificial layer and a method for manufacturing a semiconductor light emitting device using the same will be.

A light emitting diode (LED) is a semiconductor device capable of generating light of various colors based on recombination of electrons and holes at junctions of p-type and n-type semiconductors when current is applied thereto. These LEDs have a number of advantages over filament based light emitting devices, such as long life, low power, excellent initial driving characteristics, high vibration resistance, and high tolerance for repetitive power interruptions. In recent years, group III nitride semiconductors capable of emitting light in a blue short wavelength region have been in the spotlight.

The nitride semiconductor light emitting device is a light emitting device for obtaining light in a blue or green wavelength band, and has an Al _x In _y Ga _(1-xy) N composition formula (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ x + y). ≤ 1). The nitride semiconductor crystal is grown on a nitride single crystal growth substrate such as a sapphire substrate in consideration of lattice matching. Since the sapphire substrate is an electrically insulating substrate, the final nitride semiconductor light emitting device has a horizontal structure in which a portion of the nitride semiconductor layer and the active layer is etched to form a p-side electrode and an n-side electrode on the same plane.

Since the horizontal structure consumes a portion of the semiconductor layer and the active layer, the light emitting area of the semiconductor light emitting device is reduced, thereby reducing the light emitting efficiency.

The semiconductor light emitting device having a vertical structure does not reduce the light emitting area of the light emitting device by forming a conductive substrate to which voltage can be applied, but requires a process of removing the growth substrate. In general, when the growth substrate is removed, a laser lift-off process of irradiating a laser on the rear surface of the substrate is used. However, when the laser is irradiated on the rear surface of the growth substrate, stress is generated due to mismatch between lattice constants of the substrate and the nitride semiconductor layer and difference in thermal expansion coefficient, resulting in warpage of the substrate. In addition, the nitride semiconductor layer is damaged by the stress of the substrate and the nitride semiconductor layer, thereby lowering the yield of the device.

Another method for removing the substrate may be wet etching, which is a chemical lift off process. However, the sacrificial layer suitable for wet etching is not suitable for growth of the nitride semiconductor layer, and thus it is difficult to manufacture high quality semiconductor light emitting devices.

The present invention is to solve the above problems, to provide a method for producing a nitride single crystal having a high crystallinity on the sacrificial layer and a method for manufacturing a semiconductor light emitting device using the same.

The present invention as a means for solving the above problems, forming a sacrificial layer on a substrate; Forming a plurality of nitride single crystal seeds on the sacrificial layer; Growing the nitride single crystal seed to form a nitride single crystal; And it provides a method for producing a nitride single crystal comprising the step of separating the sacrificial layer from the nitride single crystal.

The sacrificial layer preferably includes a material that can be selectively removed, and more specifically, includes a material that can be wet etched.

It is preferable that the diameter of the said nitride single crystal seed is 100 nm-2 micrometers micrometers.

The second step includes dispersing a plurality of polymer beads on the sacrificial layer; Forming a mask material on the sacrificial layer that does not react with the polymer beads; Removing the polymer beads to form a mask layer having a plurality of openings; Forming a nitride single crystal seed on the mask layer in which the plurality of openings are formed; The method may include removing the mask layer on which the plurality of openings are formed.

The polymer beads may comprise polystyrene-based or polyurethane, and the diameter of the polymer beads is preferably 100 nm to 2 μm.

The mask material may be polyamide, the thickness of the mask layer is preferably smaller than the diameter of the polymer beads, the removal of the mask layer may use a strong acid solution.

The present invention as another means for solving the above problems, forming a sacrificial layer on the growth substrate; Forming a plurality of nitride single crystal seeds on the sacrificial layer; Growing the nitride single crystal seed to form a first conductivity type nitride semiconductor layer; Forming a light emitting structure by forming an active layer and a second conductive semiconductor layer on the first conductive nitride semiconductor layer; Forming a conductive substrate on the second conductive semiconductor layer; Separating the growth substrate and the sacrificial layer from the light emitting structure; It provides a method of manufacturing a semiconductor light emitting device comprising the step of forming a first electrode on the first conductive semiconductor layer.

Separating the growth substrate and the sacrificial layer from the light emitting structure is preferably a wet etching method.

According to the present invention, a nitride single crystal is grown around a nitride single crystal seed having a micrometer size formed on a sacrificial layer, thereby providing a nitride single crystal having high crystallinity. In addition, the sacrificial layer may be removed by wet etching, thereby manufacturing a vertical structure semiconductor light emitting device having excellent luminous efficiency.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention. 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. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, formation and size of elements in the drawings may be exaggerated for clarity, and elements represented by the same reference numerals in the drawings are the same elements.

1A to 1C are cross-sectional views illustrating a method for producing a nitride single crystal according to an embodiment of the present invention.

First, as shown in FIG. 1A, the sacrificial layer 12 is formed on the nitride growth substrate 11. The nitride single crystal growth substrate 11 is not limited thereto. For example, any one of a sapphire (α-Al ₂ O ₃ ) substrate, a silicon carbide (SiC) substrate, a silicon (Si) substrate, and a zinc oxide (ZnO) substrate may be used. It may be one substrate.

The sacrificial layer 12 preferably includes a material that can be selectively removed. More specifically, it is preferable that the wet etching is made of a material. For example, but not limited to metal; Alloys composed of binary, ternary or quaternary systems; Oxides; Nitrides; Oxynitride; Boride; Carbide; Or silicides; Can be selected from.

Preferably it may include a metal and metal nitride, a metal selected from the group consisting of Ga, Nb, V, Ta, Zr, Hf, Ti, Al, Cr, Mo, W, Cu, Fe, C, and In and It may include a metal nitride layer including the same.

Next, as shown in FIG. 1B, a plurality of nitride single crystal seeds 13a are formed on the sacrificial layer 12. The nitride single crystal seed 13a serves as a nucleus for nitride single crystal growth. The diameter of the nitride single crystal seed 13a is not limited thereto, but is preferably 100 nm to 2 μm. The nitride single crystal seed 13a can be easily formed on the sacrificial layer 12 because it has a size of micrometer level.

The nitride single crystal seed 13a is formed by depositing a crystalline phase at low temperature using physical vapor deposition (PVD). The nitride single crystal seed 13a is not limited thereto, but is highly thermally stable metal alloy, oxide, nitride, oxynitride, boride, carbide, And silicides. Preferably, SiO ₂ , SiC, AlN, TiN or InN may be used.

Finally, as shown in FIG. 1C, the nitride single crystal seed 13 a is grown to form the nitride single crystal 13 on the sacrificial layer 12. When the nitride single crystal is grown directly on the sacrificial layer 12, the nitride single crystal generates so many defects and cracks that it cannot be put to practical use. In the present invention, a nitride single crystal seed 13a that is easily deposited on the sacrificial layer 12 is first formed, and the nitride single crystal is grown using the nitride single crystal, thereby forming a high quality nitride single crystal having excellent crystallinity.

The method for producing the nitride single crystal 13 may use a method known in the art. For example, organometallic vapor deposition (MOCVD), molecular beam growth (MEB), or hybrid vapor deposition (HVPC) can be used.

During the growth of the nitride single crystal 13, the growth pressure, the growth temperature, and the like may be adjusted to control the lateral growth rate and the vertical growth rate. Specifically, the temperature and pressure are initially adjusted to increase the lateral growth rate, and when the gap between the plurality of nitride single crystal seeds 13a is filled, the temperature and pressure may be adjusted to increase the vertical growth rate.

The nitride single crystal 13 reduces the occurrence of defects such as dislocations caused by lattice mismatch between the sacrificial layer and the nitride single crystal due to growth through the nitride single crystal seed 13a.

Thereafter, the method may include separating the sacrificial layer from the nitride single crystal. The sacrificial layer is a material that can be selectively removed. For example, the nitride single crystal and the sacrificial layer may be separated by a wet etching method using a solution capable of removing the sacrificial layer.

2A to 2H are cross-sectional views illustrating a method of forming the nitride single crystal seed 23a on the sacrificial layer 22 according to the exemplary embodiment, but are not limited thereto.

First, as shown in FIG. 2A, a plurality of polymer beads 24a are dispersed on the sacrificial layer 22. Although not limited thereto, the polymer beads 24a may include polystyrene or polyurethane, and the diameter of the polymer beads may be 100 nm to 2 μm.

An aqueous solution in which a plurality of polymer beads 24a are dispersed may be formed on the sacrificial layer 22 by using a method such as dropping, dipping, and spin coating in a scanning manner. 2B is a photograph showing an upper portion of the sacrificial layer 22 having a plurality of polymer beads 24a formed thereon.

Next, as shown in FIG. 2C, the mask material 24 is coated on the sacrificial layer 22 in which the polymer beads 24a are dispersed. The mask material 24 does not react with the polymer beads 24a, and it is preferable to use a relatively viscous polymer solution. Although not limited thereto, for example, a polyamide in a solution state having a viscosity may be used. The mask material 24 does not react with the polymer beads but fills the space between the polymer beads 24a.

At this time, the thickness of the mask material 24 applied to facilitate selective removal of the polymer beads 24a is preferably smaller than the diameter of the polymer beads 24a.

Thereafter, when the mask material 24 is cured as shown in FIG. 2D, the mask material 24 is left, and only the polymer beads 24a are selectively removed. For example, a solution capable of selectively removing only the polymer beads 24a may be used, for example, a basic to strong basic solution such as acetone. As a result, a mask layer having a plurality of openings 24b exposing the surface of the sacrificial layer is formed. That is, the opening 24b is formed by removing the polymer beads 24a. FIG. 2E is a photograph showing the top of the mask layer having a plurality of openings 24b formed therein.

Next, as shown in FIG. 2F, the nitride single crystal seed 23a is formed on the mask layer on which the plurality of openings 24b are formed. In this case, the nitride single crystal seed 23a is formed in the opening 24b formed in the mask layer. That is, starting from the surface of the sacrificial layer exposed by the opening is formed in the form of a seed in the process of filling the opening.

The formation region of the nitride single crystal seed can be adjusted according to the position, number and shape of the openings of the mask layer. Thereafter, only the mask layer is selectively removed, except for the nitride single crystal seed, as shown in FIG. 2G. The mask layer may be removed by a strong acid solution, for example, tetrachloroethane (TCE) or sulfuric acid may be used.

Thereafter, as shown in FIG. 2H, the nitride single crystal 23 is grown around the nitride single crystal seed 23a. As described above, the nitride single crystal 23 can be grown using methods known in the art. For example, organometallic vapor deposition (MOCVD), molecular beam growth (MEB), or hybrid vapor deposition (HVPC) can be used.

3A to 3B are cross-sectional views illustrating a method of manufacturing a nitride semiconductor light emitting device according to one embodiment of the present invention.

First, as shown in FIG. 3A, the sacrificial layer 32, the first conductivity type nitride semiconductor layer 33, the active layer 35, and the second conductivity type nitride semiconductor layer 36 are formed on the nitride single crystal growth substrate 31. To form a light emitting structure comprising a).

As described above, the first conductivity type nitride semiconductor layer 33 may form the nitride single crystal seed 33a on the sacrificial layer 35, and then form the first conductivity type nitride semiconductor layer around the same. . In the first conductivity type nitride semiconductor layer grown through the nitride single crystal seed 31a, deformation such as dislocation defects, warpage or cracking is reduced, thereby improving crystallinity.

The first conductivity type nitride semiconductor layer 33 and the second conductivity type nitride semiconductor layer 36 are composed of Al _x In _y Ga _(1-xy) N composition formulas (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0). ≦ x + y ≦ 1, typically GaN, AlGaN, or InGaN. In addition, n-type impurities or p-type impurities may be doped in consideration of each conductivity type. Si, Ge, Se, Te, or C may be used as the n-type impurity, and Mg, Zn, or Be may be used as the p-type impurity. Although not limited thereto, the first conductive nitride semiconductor layer is preferably an n-type semiconductor layer, and the second conductive nitride semiconductor layer is preferably a p-type nitride semiconductor layer.

The active layer 35 is a layer in which light is generated by recombination of electrons and holes. In the present embodiment, the active layer 35 may be formed of a nitride semiconductor layer having a single or multiple quantum well structure.

Thereafter, a supporting substrate 37 for supporting the light emitting structure is formed on the second conductivity type nitride semiconductor layer 36. In this case, the support substrate 37 is a conductive material, and may include a material selected from the group consisting of Si, Cu, Ni, Au, W, and Ti. Subsequently, when the single crystal growth substrate 31 is removed, the light emitting structure having a relatively thin thickness can be easily handled by the support substrate 37.

Although not shown, a reflective electrode may be formed between the second conductivity type nitride semiconductor layer 36 and the support substrate 37 or after formation of the support substrate 37. Although the reflective electrode is not a necessary component in the present embodiment, the light emitted from the active layer 35 is combined with the ohmic contact function with the second conductivity type nitride semiconductor layer 36. It can contribute to the improvement of the luminous efficiency by performing the function of reflecting in the direction. For this purpose, the reflective electrode preferably has a reflectance of 70% or more, and for example, may be formed of a material including Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, and the like. In addition, the structure may be adopted in two or more layers to improve reflection efficiency. Specific examples thereof include Ni / Ag, Zn / Ag, Ni / Al, Zn / Al, Pd / Ag, Pd / Al and Ir / Ag. Ir / Au, Pt / Ag, Pt / Al, Ni / Ag / Pt, etc. are mentioned.

Next, as shown in FIG. 3B (upside down), the growth substrate 31 and the sacrificial layer 32 are separated from the light emitting structure to expose one surface of the first conductivity type nitride semiconductor layer 33 to the outside. . Removal of the growth substrate 31 is preferably using a wet etching method. In the wet etching method, there is no heat and mechanical impact generated when using a conventional laser lift-off method, thereby making a nitride-based semiconductor light emitting device having a superior material.

The first electrode 38 is formed for each chip device region on the first conductivity type nitride semiconductor layer 33. In this case, a pattern may be formed on the top surface of the first conductivity type nitride semiconductor layer 33 to improve light extraction efficiency. Thereafter, a plurality of semiconductor light emitting devices are manufactured by separating the chip units.

While the above has been shown and described with respect to preferred embodiments of the present invention, the present invention is not limited to the above-described appropriate embodiments, it is usually in the art without departing from the gist of the invention claimed in the claims. Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

1A to 1C are cross-sectional views showing a process for producing a nitride single crystal according to an embodiment of the present invention.

2A to 2H are cross-sectional views showing a process for producing a nitride single crystal according to another embodiment of the present invention.

3A and 3B are cross-sectional views illustrating a method of manufacturing a semiconductor light emitting device according to one embodiment of the present invention.

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

11, 21, 31: substrate for nitride single crystal growth 12, 22, 32: sacrificial layer

13, 23: nitride single crystal 13a, 23a: nitride single crystal seed

24: mask layer 24a: polymer beads

33: first conductivity type nitride semiconductor layer 35: active layer

36: second conductivity type nitride semiconductor layer 37: support substrate

38: first electrode

Claims (12)

Forming a sacrificial layer on the substrate; Forming a plurality of nitride single crystal seeds on the sacrificial layer; Growing the nitride single crystal seed to form a nitride single crystal; And Removing the sacrificial layer from the nitride single crystal. The method of claim 1, And the sacrificial layer comprises a material capable of selective removal. The method of claim 1, The sacrificial layer is a method for producing a nitride single crystal characterized in that it comprises a material capable of wet etching. The method of claim 1, The nitride single crystal seed has a diameter of 100nm to 2㎛ method of producing a nitride single crystal. The method of claim 1, Forming the single crystal seed Dispersing a plurality of polymer beads on the sacrificial layer; Forming a mask material on the sacrificial layer that does not react with the polymer beads; Removing the polymer beads to form a mask layer having a plurality of openings; Forming a nitride single crystal seed on the mask layer in which the plurality of openings are formed; Removing the mask layer having the plurality of openings formed therein. The method of claim 5, The polymer beads are a method for producing a nitride single crystal, characterized in that containing polystyrene-based or polyurethane. The method of claim 5, The diameter of the polymer beads is 100nm to 2㎛ 방법 The method of producing a nitride single crystal. The method of claim 5, And the mask material is polyamide. The method of claim 5, And the thickness of the mask layer is smaller than the diameter of the polymer beads. The method of claim 5, The removal of the mask layer is a method for producing a nitride single crystal, characterized in that using a strong acid solution. Forming a sacrificial layer on the growth substrate; Forming a plurality of nitride single crystal seeds on the sacrificial layer; Growing the nitride single crystal seed to form a first conductivity type nitride semiconductor layer; Forming a light emitting structure by forming an active layer and a second conductive nitride semiconductor layer on the first conductive nitride semiconductor layer; Forming a conductive substrate on the second conductive semiconductor layer; Separating the growth substrate and the sacrificial layer from the light emitting structure; Forming a first electrode on the first conductive semiconductor layer. The method of claim 11, The separating of the growth substrate and the sacrificial layer from the light emitting structure is a method of manufacturing a semiconductor light emitting device, characterized in that using a wet etching method.

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