TW201417338A - Semiconductor light emitting diode - Google Patents

Abstract

The present invention relates to a semiconductor light-emitting element comprising a light-emitting region separation trench and a contact hole structure. A semiconductor light-emitting element, according to the present invention, can widen an effective light-emitting area by evenly dispersing a current flowing through a semiconductor layer. In addition, according to the separation of each light-emitting region by a light-emitting region separation trench, an effect can be obtained such that individual elements are connected in parallel, and the improvement of optical efficiency can also be expected.

Description

Semiconductor light-emitting element

The present invention relates to a semiconductor light-emitting device comprising a light-emitting region separation trench and a contact hole structure, thereby exhibiting an excellent current dispersion effect and improving luminance characteristics.

Examples of the conventional semiconductor light-emitting device include, for example, a gallium nitride (GaN)-based nitride semiconductor light-emitting device, and the above-described gallium nitride-based nitride semiconductor light-emitting device can be applied to a blue or green LED in its application field. High-speed switching elements such as light-emitting elements, metal semiconductor field effect transistors (MESFETs), and high electron mobility transistors (HEMTs), high-power elements, and the like.

The first figure briefly shows a general nitride-based semiconductor light-emitting device.

Referring to the first figure, the nitride-based semiconductor light-emitting element is formed of the growth substrate 11. More specifically, the nitride-based light-emitting element includes the n-type nitride semiconductor layer 12, the active layer 13, and the p-type nitride semiconductor layer 14.

Further, in order to inject electrons into the n-type nitride semiconductor layer 12, an n-side electrode pad 15 to be electrically connected is formed in the n-type nitride semiconductor layer 12. Further, in order to inject holes into the p-type nitride semiconductor layer 14, a p-side electrode pad 16 to be electrically connected is formed in the p-type nitride semiconductor layer 14.

On the other hand, the p-type nitride semiconductor layer has a high resistivity. So at p The current cannot be uniformly dispersed in the type nitride semiconductor layer, and the current is concentrated on the portion where the p-side electrode plate is formed.

Further, a current flows through the semiconductor layer and is lost to the n-side electrode pad. Thereby, the current concentrates on the portion where the n-side electrode pad is formed in the n-type nitride semiconductor layer, and a problem arises in that current concentrates through the corners of the semiconductor light-emitting element. The concentration of the current as described above causes a reduction in the light-emitting area, ultimately reducing the luminous efficiency.

In particular, the planar structure light-emitting elements in which the two electrodes are arranged almost in the horizontal manner on the upper surface of the light-emitting structure are not uniformly distributed over the entire light-emitting area as compared with the vertical structure light-emitting elements, so that there are The problem of a small effective area for illuminating.

On the other hand, like the light-emitting element for illumination, the light-emitting element gradually approaches a large area of about 1 mm ² or more for high power. However, as the light-emitting element is formed to have a large area, there is a problem that it is difficult to achieve uniform distribution of current in the entire area. Thus, the problem of current dispersion according to a large area is considered to be an important technical problem in a semiconductor light-emitting element.

Conventionally, in order to improve the current density and improve the area effectiveness, it has been studied to improve the morphology and arrangement direction of a plurality of p-side electrodes and n-side electrodes. As an example, a light-emitting element including a plurality of electrode grids extending and meshing with each other at a predetermined interval from the n-side electrode and the p-side electrode is disclosed in U.S. Patent No. 6,486,499. It is desirable to provide an additional current path through such an electrode structure, ensuring a wide effective light-emitting area and forming a uniform current flow.

However, in such an electrode structure, as the current density of the p-type nitride semiconductor layer near the p-side electrode increases, the output efficiency decreases, and the current dispersion efficiency is limited. system.

Therefore, there is a continuing need to develop a semiconductor light-emitting element that can uniformly disperse a current flowing through a semiconductor layer.

As a result, in order to develop a semiconductor light-emitting device having a structure capable of achieving an excellent current dispersion effect, the inventors of the present invention have found that the inside of the contact hole formed to expose the first semiconductor layer is formed. a first extension electrode exposed to the first semiconductor layer of the upper portion of the second semiconductor layer to electrically connect, and forming a trench capable of separating the light-emitting region into a plurality, and between the second semiconductor layer and the first extension electrode Forming an insulating layer between the sidewall of the contact hole and the first extension electrode and between the surface of the trench and the first extension electrode to form a semiconductor light-emitting device having a plurality of light-emitting regions, thereby maximizing current dispersion The brightness can be increased to complete the present invention.

Accordingly, an object of the present invention is to provide an electrode structure having an excellent current dispersion effect and a semiconductor light-emitting element having a light-emitting region separating trench.

A semiconductor light emitting device of the present invention which achieves the above object is characterized by comprising a first semiconductor layer, an active layer, a second semiconductor layer, a contact hole for current diffusion, and a trench.

Further, in the semiconductor light emitting device of the present invention, the light emitting region is separated into a plurality of regions by the trench.

Further, in the semiconductor light emitting device of the present invention, the current diffusion contact hole is formed to expose the first semiconductor layer, and includes: a first extension electrode and a second extension electrode, wherein the first extension electrode is used for Electrical connection by the above current diffusion contact hole The exposed first semiconductor layer is electrically connected to the second extension layer.

Further, the semiconductor light emitting device of the present invention is characterized by comprising an insulating layer for electrically insulating the first extension electrode from the active layer, the second semiconductor layer or the trench region, and for the second extension electrode Electrically insulating from the trench region, and the insulating layer is formed between the second semiconductor layer and the first extension electrode, between the sidewall of the current diffusion contact hole and the first extension electrode, and the surface of the trench Between the first extension electrode and the first extension electrode.

The semiconductor light-emitting device of the present invention can uniformly disperse a current flowing through the semiconductor layer to expand the effective light-emitting area.

Further, as the respective light-emitting regions are separated by the light-emitting region separating grooves, it is possible to obtain the same effect as the individual elements being connected in parallel, and it is expected that the light efficiency can be improved.

Prior art

11‧‧‧ Growth substrate

12‧‧‧n type nitride semiconductor layer

13‧‧‧Active layer

14‧‧‧p-type nitride semiconductor layer

15‧‧‧n side electrode plate

16‧‧‧p side electrode plate

this invention

110‧‧‧Contact hole

111‧‧‧n side extension electrode

112‧‧‧n side electrode plate

120‧‧‧ trench

121‧‧‧p side extension electrode

122‧‧‧p side electrode plate

130‧‧‧Substrate

140‧‧‧buffer layer

150‧‧‧n type nitride layer

151‧‧‧n-contact layer

160‧‧‧active layer

170‧‧‧p type nitride layer

171‧‧‧p-contact layer

180‧‧‧Insulation

The first figure is a cross-sectional view of a conventional semiconductor light emitting device.

The second figure is a plan view of a semiconductor light emitting element according to an embodiment of the present invention.

The third figure is a cross-sectional view taken from the intercept line A-A of the second figure.

The fourth figure is a cross-sectional view taken from the cut line B-B of Fig. 2.

Fig. 5 is a plan view showing a semiconductor light emitting device of a comparative example of the present invention.

Hereinafter, a semiconductor light emitting device according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the following embodiments, the first semiconductor layer is an n-type nitride layer, the second semiconductor layer is a p-type nitride layer, the first extension electrode is an n-side extension electrode, and the second extension electrode is a p-side extension. The electrode, the first electrode plate is an n-side electrode plate, and the second electrode plate is a p-side electrode plate.

The second drawing is a plan view of the level-type semiconductor light-emitting device of the first embodiment of the present invention.

As shown in the second figure, the light-emitting element of the present invention includes a light-emitting region separating trench 120 that penetrates the p-type nitride layer and the active layer to separate the light-emitting region into a plurality of regions.

Further, the contact hole 110 may be further provided, and the contact hole 110 may be formed to penetrate the p-type nitride layer and the active layer together with the light-emitting region separating trench 120 to expose the n-type nitride layer.

Further, an upper portion of the p-type nitride layer and the light-emitting region separating trench 120 inside the contact hole includes an n-side extension electrode 111 for electrically connecting the n-type nitride layer exposed through the contact hole 110. The light-emitting region separating trench 120 may be formed in a direction perpendicular to the n-side extension electrode 111. The n-side extension electrode 111 is electrically connected to the n-side electrode pad 112, and may include two or more contact holes 110 in one n-side extension electrode 111. The two or more contact holes 110 may be formed separately from each other and regularly formed, but the positions to be formed are not particularly limited, and may be arranged in various forms that are not linear.

Further, the p-side extension electrode 121 is electrically connected to a part of the p-side electrode pad 122 located in the upper portion of the p-type nitride layer, thereby forming a p-side electrode portion. The n-side extension electrode 111 is formed to be electrically insulated from the p-side extension electrode 121.

To illustrate a more specific structure, cross-sectional views taken along the intercept lines A-A, B-B of the second figure are shown in the third and fourth figures.

As shown in the third figure, the semiconductor light emitting device of the present invention faces the substrate 130 The direction of the portion is formed by laminating the buffer layer 140, the n-type nitride layer 150, the active layer 160, and the p-type nitride layer 170.

The substrate 130 may be formed of a compound containing SiC, Si, GaN, ZnO, GaAs, GaP, LiAl ₂ O ₃ , BN, or AlN including sapphire. Further, in order to release the lattice mismatch between the substrate 130 and the n-type nitride layer 150, the buffer layer 140 may be selectively formed, for example, formed of AlN or GaN.

The n-type nitride layer 150 is formed on the upper surface of the substrate 130 or the buffer layer 140, and is formed of a nitride doped with an n-type dopant. As the n-type dopant, bismuth (Si), germanium (Ge), tin (Sn), or the like can be used. Here, the n-type nitride layer 150 may be a first layer composed of Si-doped n-type AlGaN or undoped AlGaN and a second layer composed of undoped or doped n-type GaN alternately formed. Cascading structure. Of course, the n-type nitride layer 150 may be grown as a single-layer n-type nitride layer, but formed in a laminated structure of the first layer and the second layer, so that it can function as a carrier-limiting layer excellent in crystallinity without cracks.

The active layer 160 may be formed of a single quantum well structure or a multiple quantum well structure between the n-type nitride layer 150 and the p-type nitride layer 170, and electrons flowing through the n-type nitride layer 150 and passing through the p-type nitride layer 170 flowing holes re-combination to produce light. Here, the active layer 160 functions as a multiple quantum well structure, and the quantum barrier layer and the quantum well layer may be respectively composed of Al _x Ga _y In _z N (in this case, x+y+z=1,0) x 1,0 y 1,0 z 1) Formation. The active layer 160 of the structure formed by repeating such a quantum barrier layer and a quantum well layer can suppress spontaneous polarization due to stress and deformation generated.

The p-type nitride layer 170 is formed of a nitride doped with a p-type dopant. As the p-type dopant, magnesium (Mg), zinc (Zn), cadmium (Cd) or the like can be used. Here, p-type nitridation The material layer may be formed in a structure in which a first layer composed of Mg-doped p-type AlGaN or undoped AlGaN and a second layer composed of undoped or Mg-doped p-type GaN are alternately stacked. Further, the p-type nitride layer 170 may be grown as a single-layer p-type nitride layer like the n-type nitride layer 150. However, it may be formed in a laminated structure, so that it can act as a carrier having excellent crystallinity without cracks. Floor.

The contact hole 110 is formed to penetrate the p-type nitride layer 170 and the active layer 160 to expose the n-type nitride layer 150. Then, the p-type nitride layer 170 and the active layer 160 are etched to form the light-emitting region separating trench 120.

The contact hole 110 and the trench 120 may be formed by a photoresist or the like as a pattern mask, and in the case of using a photoresist, photo-lithography or electron beam lithography (e- may be used). Beam lithography), Ion-beam Lithography, Extreme Ultraviolet Lithography, Proximity X-ray Lithography, or nano imprint Lithography The method is formed, and such a method can utilize Dry or Wet etching.

An n-contact layer 151 may also be included on the n-type nitride layer 150 exposed by the contact hole 110 described above. The n-contact layer 151 is in ohmic contact with the n-type nitride 150 to lower the contact resistance. The n-contact layer 151 may be composed of a transparent conductive oxide, and the material thereof may include an element of In, Sn, Al, Zn, Ga, or the like, and may be, for example, one of ITO, CIO, ZnO, NiO, and In ₂ O ₃ . form.

Further, an insulating layer 180 is formed on the sidewall of the contact hole 110 for separating the sidewall of the contact hole 110 and the n-side extension electrode 111, and exposing a part of the n-type nitride layer exposed by the contact hole 110. Moreover, the insulating layer 180 extends toward the upper portion of the p-type nitride 170, thereby The p-type nitride layer 170 and the n-side extension electrode 111 are separated and extended toward the upper portion of the trench 120 region, thereby separating the trench 120 region and the n-side extension electrode 111. The insulating layer 180 may be formed of tantalum oxide or hafnium nitride, or may be a plasma enhanced chemical vapor deposition (PECVD) method, a sputtering method, or a metal organic chemical chemical weather precipitation method (MOCVD). Or formed by electron beam evaporation (e-beam evaporation).

The n-side extension electrode 111 is formed inside the contact hole 110, the upper portion of the p-type nitride layer 170, and the upper portion of the trench 120, and functions to electrically connect the n-type nitride layer exposed by the contact hole 110. It is formed of a metal, an alloy, a metal oxide, or the like that can be electrically connected.

Further, the n-side extension electrode 111 is electrically connected to the n-side electrode pad 112 existing on the insulating layer 180.

The p-contact layer 171 may be formed under the p-side extension electrode 121 partitioned from the n-side extension electrode 111, and the p-contact layer 171 may be in ohmic contact with the p-type nitride layer 170 to lower the contact resistance. The p-contact layer 171 may be made of a transparent conductive oxide, and the material thereof may include an element such as In, Sn, Al, Zn, or Ga. For example, it may be one of ITO, CIO, ZnO, NiO, and In ₂ O ₃ . A form.

As shown in the fourth figure, the buffer layer 140, the n-type nitride layer 150, the active layer 160, the p-type nitride layer 170, and the p-contact layer 171 are sequentially formed in the lower portion of the p-side extension electrode 121 toward the upper direction of the substrate 130. A region of the trench 120 in which the active layer 160 and the p-type nitride layer 170 are etched is also formed, and the p-side extension electrode 121 is electrically connected to the p-side electrode pad 122. Further, the trench 120 is electrically insulated from the p-side extension electrode 121 by the insulating layer 180. As shown in FIG. 3, the insulating layer 180 separating the p-contact layer 171 from the sidewalls and the bottom surface of the trench 120 may be used to separate the sidewalls of the n-side extension electrode 111 and the contact hole 110 and the p-type nitride layer 170. The insulating layer 180 is connected or separated from the terrain to make.

On the other hand, as shown in the plan view of the second figure, the cross section of the contact hole 110 may be formed as a circle, but is not limited thereto, and may be formed in a triangular shape, a quadrangular shape or a polygonal form.

Further, the diameter of the cross section of the contact hole 110 may be in the range of 1 μm to 200 μm, preferably in the range of 5 μm to 150 μm, and in the case where two or more contact holes are formed, the cross-sectional dimensions may be the same or different.

The distance between the adjacent contact holes 110 in the one n-side extension electrode 111 may be different according to the cross-sectional area of the entire light-emitting element, but preferably, between the adjacent contact holes 110 in the one n-side extension electrode The distance is adjusted in the range of 10 μm to 500 μm, and more preferably in the range of 50 μm to 400 μm.

On the other hand, the width of the light-emitting region separating trench 120 is in the range of 0.5 μm to 20 μm, preferably in the range of 3 μm to 10 μm.

Further, the width of the n-side extension electrode 111 can be adjusted to be 1 μm to 100 μm, preferably adjusted to be in the range of 5 μm to 50 μm, but is not limited thereto. In particular, the n-side extension electrode 111 may be formed in a constant maintaining manner, but the further away from the n-side electrode pad 112, the more the width of the n-side extension electrode 111 connecting the contact holes is reduced, and conversely, in the above-mentioned one n The farther from the n-side electrode pad 112 in the side extension electrode, the wider the width of the n-side extension electrode 111 for connecting the contact hole.

The n-side electrode pad 112 may be electrically connected to one or two or more n-side extension electrodes 111. In this case, one or more contact holes may be formed in each of the n-side extension electrodes. In particular, the n-side extension electrode 111 can form not only a straight line shape without a bending point, but also It is formed into a form having one or more bending points.

Further, the p-side electrode pad 122 may be electrically connected to one or two or more p-side extension electrodes 121. When the two or more p-side extension electrodes 121 are formed, they are generally separated at the ends of the opposite surfaces that are not connected to the p-side electrode pad 122, but the ends may be connected to each other to form a closed pattern. As described above, even if the terminals of the p-side extension electrodes 121 are connected to each other, it is possible to separate from the n-side extension electrodes 111 by means of an insulating layer, as will be apparent to those skilled in the art. Further, the p-side electrode pad 122 may be electrically connected to one or two or more p-side extension electrodes 121. When the two or more p-side extension electrodes 121 are formed, they are generally separated at the ends of the reverse side that are not connected to the p-side electrode pad 122, but the ends may be connected to each other to form a closed pattern. As described above, even if the terminals of the p-side extension electrodes 121 are connected to each other, it is possible to separate from the n-side extension electrodes 111 by means of an insulating layer, as will be apparent to those skilled in the art.

The light-emitting region of the semiconductor light-emitting device of the present invention described above can be divided into a plurality of regions by the above-described trenches 120, and as shown in the second diagram, in the case where two trenches 120 are formed, the light-emitting regions are separated into three regions. As the trench 120 region is formed between the plurality of contact holes 110 described above, each of the light emitting regions will have more than one contact hole 110. The number of light-emitting regions separately formed by means of the above-described grooves in one element is not greatly limited, but is preferably separated into three to five regions, more preferably at equal intervals, so that the respective light-emitting portions are formed. The area of the area is even.

With the separation of the above-described light-emitting regions, the respective light-emitting regions can obtain the same effect as the parallel connection of the individual elements by the n-side extension electrode 111 and the p-side extension electrode 121, and the current dispersion effect based on the plurality of contact holes can be expected, and the current density can be improved. To increase the brightness.

Hereinafter, the semiconductor light-emitting element of the present invention is applied by the following embodiments of the present invention A more specific description.

Example

In order to constitute the semiconductor light-emitting element as shown in the second to fourth embodiments, gallium nitride is used as the nitride layer of the nitride light-emitting element, and is applied to the sapphire substrate, and as the extended electrode, a general Au base electrode is used to obtain light. element.

Comparative example

A nitride-based component which is the same as that of the embodiment is laminated on a sapphire substrate, and a light-emitting element having a plan view as shown in FIG. 5 is prepared.

The light-emitting power in the light-emitting elements of the above-described examples and comparative examples was measured by inputting the same current of 120 mA in the element state, and the results are shown in Table 1 below.

As shown in the above Table 1, it was confirmed that the light-emitting element of the example has an improvement in optical power characteristics of about 3.1% or more as compared with the comparative example. Therefore, it can be confirmed that the light-emitting element of the embodiment can exhibit excellent performance. Optical power characteristics.

The embodiments of the present invention have been described above, but are merely illustrative, and other embodiments that can be modified and equivalent can be understood by those skilled in the art to which the present invention pertains. Therefore, the true technical protection scope of the present invention should be judged based on the scope of the patent application described below.

110‧‧‧Contact hole

111‧‧‧n side extension electrode

112‧‧‧n side electrode plate

120‧‧‧ trench

121‧‧‧p side extension electrode

130‧‧‧Substrate

140‧‧‧buffer layer

150‧‧‧n type nitride layer

151‧‧‧n-contact layer

160‧‧‧active layer

170‧‧‧p type nitride layer

171‧‧‧p-contact layer

180‧‧‧Insulation

Claims (16)

A semiconductor light emitting device comprising: a first semiconductor layer; an active layer formed on the first semiconductor layer; a second semiconductor layer formed on the active layer; and a trench for the second semiconductor layer and The active layer is separated into a plurality of regions. The semiconductor light-emitting device according to the first aspect of the invention, wherein the trench is formed such that respective areas of the plurality of regions separated by the trench are uniform. The semiconductor light-emitting device according to claim 1, further comprising a current diffusion contact hole, the current diffusion contact hole forming the first semiconductor layer in a plurality of ways separated by the trench region. The semiconductor light emitting device according to claim 3, further comprising: a first extension electrode for electrically connecting the first semiconductor layer exposed through the current diffusion contact hole; and a second extension electrode, Electrically connecting to the second semiconductor layer. The semiconductor light emitting device of claim 4, further comprising: an insulating layer for electrically connecting the first extension electrode and the active layer, the second semiconductor layer or the trench region Insulating and electrically insulating the second extension electrode and the trench region. The semiconductor light emitting device according to claim 5, wherein the insulating layer is formed between the second semiconductor layer and the first extension electrode, between the sidewall of the current diffusion contact hole and the first extension electrode, and The surface of the trench is between the first extension electrode. The semiconductor light emitting device of claim 4, wherein the first extended electricity The pole is formed inside the contact hole for current diffusion, the upper portion of the second semiconductor layer and the trench. The semiconductor light-emitting device according to claim 4, wherein two or more of the current diffusion contact holes are included in the first extension electrode. The semiconductor light emitting device of claim 4, further comprising: a first electrode pad electrically connected to the first extension electrode; and a second electrode pad electrically connected to the second extension electrode connection. The semiconductor light-emitting device according to the third aspect of the invention, wherein the diameter of the cross section of the current diffusion contact hole is in the range of 1 μm to 200 μm. The semiconductor light-emitting device according to claim 3, wherein the cross section of the current diffusion contact hole has a circular, triangular or quadrangular shape. The semiconductor light-emitting device according to Item 1, wherein the width of the trench is in the range of 0.5 μm to 20 μm. A semiconductor light emitting device comprising: a first semiconductor layer; an active layer formed on the first semiconductor layer; a second semiconductor layer formed on the active layer; a trench for the second semiconductor layer and active Separating the layers into a plurality of regions; a contact hole for current diffusion, the first semiconductor layer being formed in an exposed manner in a plurality of regions separated by the trench; and a first extension electrode for contacting the contact hole through the current diffusion The exposed first semiconductor layer is electrically connected; and an insulating layer to the first extension electrode and the active layer, the second semiconductor layer or the trench region Electrically insulated. The semiconductor light emitting device according to claim 13, wherein the insulating layer is formed between the second semiconductor layer and the first extension electrode, between the sidewall of the current diffusion contact hole and the first extension electrode, and The surface of the trench is between the first extension electrode. The semiconductor light-emitting device according to claim 13, wherein the first extension electrode is formed inside the current diffusion contact hole, the second semiconductor layer, and the upper portion of the trench. The semiconductor light emitting device of claim 13, further comprising: a second extension electrode electrically connected to the second semiconductor layer; the insulating layer to the second extension electrode The trench regions are formed by electrical insulation.