KR100782433B1 - Method for fabricating a light emitting diode of a nitride compound semiconductor and a light emitting diode fabricated by the method - Google Patents

Abstract

A method for manufacturing a light emitting diode of a nitride semiconductor and a light emitting diode manufactured by the method are provided to reduce crystal defects and an active layer and to increase the light emitting efficiency of the light emitting diode by forming a repetition layer. A buffer layer(23) is formed on a substrate(21). A first conductive-type lower semiconductor layer(25) of a AlxInyGa(1-x-y)N material film is formed on the buffer layer. A discontinuous layer(27) of SiN material and a first conductive-type upper semiconductor layer(29) of a AlxInyGa(1-x-y)N material film are alternatively formed on the first conductive-type lower semiconductor layer to form a repetition layer(28). An active layer(31) is formed on the repetition layer. A second conductive-type semiconductor layer(33) of a AlxInyGa(1-x-y)N material film is formed on the active layer.

Description

FIELD OF THE INVENTION A method for manufacturing a nitride semiconductor light emitting diode and a light emitting diode manufactured by the same.

1 is a cross-sectional view illustrating a conventional method for manufacturing a nitride semiconductor light emitting diode.

2 to 6 are cross-sectional views illustrating a method of manufacturing a nitride semiconductor light emitting diode according to an embodiment of the present invention.

The present invention relates to a method for manufacturing a nitride semiconductor light emitting diode and a light emitting diode produced by the same, and more particularly, to a method for manufacturing a nitride semiconductor light emitting diode capable of reducing the density of crystal defects in the active layer and a light emitting diode produced by the same will be.

In general, nitrides of group III elements, such as gallium nitride (GaN) and aluminum nitride (AlN), have excellent thermal stability and have a direct transition energy band structure. As a lot of attention. In particular, blue and green light emitting diodes using gallium nitride (GaN) are used in various applications such as large-scale color flat panel display devices, traffic lights, indoor lighting, high density light sources, high resolution output systems, and optical communications.

The nitride semiconductor layer of the group III element is grown through a process such as metal organic chemical vapor deposition (MOCVD) on a heterogeneous substrate such as sapphire or silicon carbide (SiC) having a hexagonal structure. However, when a nitride semiconductor layer of a group III element is formed on a dissimilar substrate, cracks or warpage occur in the semiconductor layer due to a difference in lattice constant and thermal expansion coefficient between the semiconductor layer and the substrate, Dislocations are created. Cracks, distortions and dislocations in the semiconductor layer deteriorate the characteristics of the light emitting diode. Therefore, a buffer layer is generally used to relieve stress due to the lattice constant and thermal expansion coefficient difference between the substrate and the semiconductor layer.

1 is a cross-sectional view for explaining a method of manufacturing a conventional nitride semiconductor light emitting diode.

Referring to FIG. 1, a buffer layer 13 is formed on a substrate 11. The buffer layer 13 is generally formed of Al _x Ga _1-x N (0 ≦ _x ≦ 1) using a MOCVD process or the like. Subsequently, an n-type GaN layer 15 is formed on the buffer layer 13, and an active layer 17 and a p-type GaN layer are formed thereon.

According to the prior art, by forming a buffer layer 13 between the n-type GaN layer 15 and the substrate 11, cracks due to the lattice constant and thermal expansion coefficient difference between the substrate 11 and the semiconductor layer 15 and The occurrence of dislocations and the like can be reduced.

However, despite the adoption of the buffer layer 13, the crystal defect density in the active layer is still high. Crystal defects in the active layer are generated by transferring the crystal defects of the n-type GaN layer 15, which reduces the luminous efficiency.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a nitride semiconductor light emitting diode manufacturing method capable of reducing crystal defects in an active layer and a nitride semiconductor light emitting diode manufactured thereby.

In order to achieve the above technical problem, the present invention provides a method for manufacturing a nitride semiconductor light emitting diode and a light emitting diode produced by the same. In the LED manufacturing method according to an aspect of the present invention, a buffer layer is formed on a substrate, and Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + ₎ is formed on the buffer layer. Y≤1) forming the first conductivity type lower semiconductor layer of the material film. A discontinuous layer of SiN material and a first film of an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material layers on the first conductive lower semiconductor layer A repeating layer in which the conductive upper semiconductor layers are alternately stacked at least twice is formed. Thereafter, an active layer is formed on the repeating layer, and an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material film is formed on the active layer. A two conductivity type semiconductor layer is formed. The repeating layer may prevent the crystal defects in the first conductivity type lower semiconductor layer from being transferred to the active layer, thereby reducing the density of crystal defects in the active layer.

In addition, the first conductivity type lower semiconductor layer, the discontinuous layer and the first conductivity type upper semiconductor layer are preferably continuously formed in the same process chamber.

In addition, a nitride semiconductor light emitting diode according to another aspect of the present invention, Al _X In _Y Ga _(1-XY) N (where 0≤X, Y≤1 and 0≤X + Y≤1) ) The first conductive lower semiconductor layer of the material film. A buffer layer may be interposed between the substrate and the first conductive lower semiconductor layer. Meanwhile, a discontinuous layer of SiN material and an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material films may be formed on the first conductive lower semiconductor layer. A repeating layer in which the first conductive upper semiconductor layer is alternately stacked at least twice is positioned. An active layer is positioned on the repeating layer, and a second conductive semiconductor of an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material layer is formed on the active layer. The floor is located. Accordingly, the repeating layer prevents the crystal defects of the first conductivity type lower semiconductor layer or the first conductivity type upper semiconductor layer located below from being transferred to the upper semiconductor layer, thereby reducing the density of crystal defects in the active layer.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention; The following embodiments are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. In the drawings, widths, lengths, thicknesses, and the like of components may be exaggerated for convenience. Like numbers refer to like elements throughout.

2 to 6 are cross-sectional views illustrating a method of manufacturing a nitride semiconductor light emitting diode according to an embodiment of the present invention.

Referring to FIG. 2, a buffer layer 23 is formed on the substrate 21. The substrate may be sapphire, silicon carbide (SiC), zinc oxide (ZnO), gallium arsenide (GaAs), gallium nitride (GaN), silicon (Si), lithium aluminum oxide (LiAlO ₂ ) or lithium gallium oxide (LiGaO ₂ ). It may be a sapphire or SiC substrate. The buffer layer 23 may be formed of an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material films, and typically, AlN, GaN, or AlGaN. Etc. are used.

The buffer layer 23 can be formed using a MOCVD process. That is, the buffer layer 23 supplies TMA, TMI, TMG, TEA and / or TEG as a source gas in a chamber at 400 to 800 ° C, and supplies ammonia and / or dimethyl hydrazine (hereinafter referred to as DMHy) as a reaction gas. The substrate 21 may be formed to a thickness of 20 kPa to 10000 kPa. When the buffer layer 23 is formed of AlN, TMA or TEA may be used as the source gas, and when the buffer layer is formed of GaN, TMG or TEG may be used as the source gas.

The first conductive lower semiconductor layer 25 of Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material film is formed on the buffer layer 23. Is formed. The first conductivity type lower semiconductor layer 25 may be formed using a MOCVD process at a chamber temperature of 900 ~ 1200 ℃. That is, the lower semiconductor layer 25 may be formed by increasing the chamber temperature in the same process chamber as the buffer layer 23, and may include TMA, TMI, TMG, It is formed by supplying TEA, TMAA, DMEAA and / or TEG, supplying ammonia and / or DMHy as a reaction gas, and doping silicon (Si).

Meanwhile, in order to reduce the crystal defect density in the first conductivity type lower semiconductor layer 25, an undoped nitride semiconductor layer (not shown) is further formed before the first conductivity type lower semiconductor layer 25 is formed. can do.

Referring to FIG. 3, a discontinuous layer 27 of silicon nitride (SiN) material is formed on the first conductive lower semiconductor layer 25.

The discontinuous layer 27 may be formed in a temperature range of 900 ~ 1200 ℃ using the MOCVD process. Therefore, after the first conductive lower semiconductor layer 25 is formed, the discontinuous layer 27 may be continuously formed in the same chamber. As the discontinuous layer 27 is formed at a high temperature, silicon nitride (SiN) material is dispersed on the first conductive lower semiconductor layer 25 in an island form, thereby forming a surface of the first conductive lower semiconductor layer 25. Partially exposed.

Meanwhile, the discontinuous layer 27 blocks TMA, TMG, TEA or TEG, which is a source gas used when the first conductive lower semiconductor layer 25 is formed, and blocks ammonia and silane (SiH4) as a source gas. Can be used.

Referring to FIG. 4, an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material layers are formed on a substrate on which the discontinuous layer 27 is formed. The semiconductor layer 29 is formed. Thus, the upper semiconductor layer 29 covers the discontinuous layer 27 and the first conductive lower semiconductor layer 25.

The upper semiconductor layer 29 may be formed using a MOCVD process, like the first conductive lower semiconductor layer 25. That is, the upper semiconductor layer 29 supplies TMA, TMI, TMG, TEA, TMAA, DMEAA and / or TEG as a source gas in a chamber at a temperature of 900 to 1200 ° C., and supplies ammonia and / or DMHy as a reaction gas. Can be formed.

In addition, the upper semiconductor layer 29 is preferably the same first conductive type as the first conductive lower semiconductor layer 25.

The first conductivity type upper semiconductor layer 29 is grown on the surface of the first conductivity type lower semiconductor layer 25. That is, the exposed surface of the first conductivity type lower semiconductor layer 25 serves as a seed of the first conductivity type upper semiconductor layer 29. Therefore, after the first conductivity type upper semiconductor layer 27 is grown beyond the height of the discontinuous layer 27, the first conductive upper semiconductor layer 27 may grow horizontally with respect to the substrate 21, and thus the crystal defect density may be reduced.

In addition, the first conductive upper semiconductor layer 29 is preferably the same first conductive type as the first conductive lower semiconductor layer 25.

Referring to FIG. 5, the discontinuous layer 27 and the first conductivity type upper semiconductor layer 29 are alternately formed a plurality of times, and thus a repeating layer 28 is formed. The discontinuously repeated discontinuous layer and the first conductive upper semiconductor layer 29 may be formed of the same material, but are not limited thereto and may be formed of different materials.

The discontinuous layer 27 repeatedly formed is mainly formed at a crystal defect position of the first conductive upper semiconductor layer 29 disposed below the semiconductor layer 29 to block crystal defects in the first conductive upper semiconductor layer 29. . Therefore, the first conductivity-type upper semiconductor layers 29 formed on each discontinuous layer 27 have a lower crystal defect density toward the top.

As a result, the discontinuous layer 27 is mainly formed at the crystal defect position of the first conductivity type lower semiconductor layer 25 or the first conductivity type upper semiconductor layer 29 to prevent the crystal defects from transferring upward, Since the first conductive upper semiconductor layer 29 grows horizontally, the density of crystal defects in the first conductive upper semiconductor layer 29 increases as the alternating repetitions are repeated. Significantly reduced compared to density.

Here, the first conductivity type upper semiconductor layer 29 positioned at the uppermost layer of the repeating layer 28 is more than the first conductivity type upper semiconductor layer 29 positioned below to form a semiconductor layer free of crystal defects. It is preferable to form the thickness sufficiently thick.

Referring to FIG. 6, an active layer 31 is formed on the repeating layer 28. The active layer 31 may be formed using a MOCVD process at a chamber temperature of 700 ~ 1200 ℃, it may be formed to have a single quantum well or multiple quantum well structure. The active layer 31 may be continuously formed in the same process chamber as the repeating layer 28 forming chamber.

The active layer 31 may be formed of an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material films, and each may be formed according to the required emission wavelength. The composition ratio of the metal element is determined.

Meanwhile, the second conductive semiconductor layer 33 of Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material film is formed on the active layer 31. Is formed. When the first conductivity type is n-type, the second conductivity-type semiconductor layer 33 is p-type and may be formed by doping Mg. In addition, when the first conductivity type is p-type, the second conductivity-type semiconductor layer 33 is n-type and may be formed by doping Si.

According to the embodiments of the present invention, the first conductive upper semiconductor layer having less crystal defects may be provided by forming a repeating layer in which discontinuous layers and upper semiconductor layers are alternately stacked on the first conductive lower semiconductor layer. As a result, the density of crystal defects in the active layer formed on the repeating layer may be reduced, thereby improving luminous efficiency of the light emitting diode.

Claims (5)

Forming a buffer layer on the substrate, Forming a first conductive lower semiconductor layer of an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material film on the buffer layer, A discontinuous layer of SiN material and a first film of an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material layers on the first conductive lower semiconductor layer Alternately stacking the conductive upper semiconductor layer at least twice to form a repeating layer, An active layer is formed on the repeating layer, A nitride semiconductor comprising forming a second conductive semiconductor layer of an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material film on the active layer. Light emitting diode manufacturing method. The method according to claim 1, And the first conductive lower semiconductor layer, the discontinuous layer and the first conductive upper semiconductor layer are continuously formed in the same process chamber. The method according to claim 1, The first conductive upper semiconductor layer formed on the uppermost layer of the repeating layer is formed thicker than the first conductive upper semiconductor layer formed below. A buffer layer located on the substrate; A first conductivity type lower semiconductor layer of an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material layer on the buffer layer; A discontinuous layer of SiN material and an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material layer on the first conductive lower semiconductor layer A repeating layer in which the first conductivity type upper semiconductor layers are alternately stacked at least twice; An active layer positioned on the repeating layer; And A nitride semiconductor light emitting device comprising a second conductive semiconductor layer of an Al _X In _Y Ga _(1-XY) N (where 0 ≦ _{X, Y} ≦ 1 and 0 ≦ X + Y ≦ 1) material layers on the active layer. diode. The method according to claim 4, The first conductive upper semiconductor layer positioned on the uppermost layer of the repeating layer is thicker than the first conductive upper semiconductor layer positioned below the nitride semiconductor light emitting diode.

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