USRE47417E1 - Semiconductor light emitting device, method of manufacturing the same, and semiconductor light emitting device package using the same - Google Patents

Abstract

There is provided a semiconductor light emitting device, a method of manufacturing the same, and a semiconductor light emitting device package using the same. A semiconductor light emitting device having a first conductivity type semiconductor layer, an active layer, a second conductivity type semiconductor layer, a second electrode layer, and insulating layer, a first electrode layer, and a conductive substrate sequentially laminated, wherein the second electrode layer has an exposed area at the interface between the second electrode layer and the second conductivity type semiconductor layer, and the first electrode layer comprises at least one contact hole electrically connected to the first conductivity type semiconductor layer, electrically insulated from the second conductivity type semiconductor layer and the active layer, and extending from one surface of the first electrode layer to at least part of the first conductivity type semiconductor layer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is aThis is a reissue application of U.S. Pat. No. 8,981,395, which was filed on Dec. 9, 2013 as U.S. Ser. No. 14/101,242 and issued on Mar. 17, 2015, which is a Continuation of application Ser. No. 13/568,553, filed on Aug. 7, 2012, now U.S. Pat. No. 8,624,276, which is a Continuation of U.S. application Ser. No. 13/163,107, filed on Jun. 17, 2011, now U.S. Pat. No. 8,263,987, which is a Continuationcontinuation of U.S. application Ser. No. 12/757,557, filed on Apr. 9, 2010, now U.S. Pat. No. 7,985,976, which is a Divisionaldivisional of U.S. patent application Ser. No. 12/189,428, filed on Aug. 11, 2008, now U.S. Pat. No. 7,964,881, which claims the priority of Korean Patent Application No. 10-2007-0105365 filed on Oct. 19, 2007, in the Korean Intellectual Property Office, the entire contents of each of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor light emitting device, a method of manufacturing the same, and a semiconductor light emitting device package using the same, and more particularly, to a semiconductor light emitting device that ensures a maximum light emitting area to maximize luminous efficiency and perform uniform current spreading by using an electrode having a small area, and enables mass production at low cost with high reliability and high quality, a method of manufacturing the same, and a semiconductor light emitting device package using the same.

2. Description of the Related Art

Semiconductor light emitting devices include materials that emit light. For example, light emitting diodes (LEDs) are devices that use diodes, to which semiconductors are bonded, convert energy generated by combination of electrons and holes into light, and emit light. The semiconductor light emitting devices are being widely used as lighting, display devices, and light sources, and development of semiconductor light emitting devices has been expedited.

In particular, the widespread use of cellular phone keypads, side viewers, and camera flashes, which use GaN-based light emitting diodes that have been actively developed and widely used in recent years, contribute to the active development of general illumination that uses light emitting diodes. Applications of the light emitting diodes, such as backlight units of large TVs, headlights of cars, and general illumination, have advanced from small portable products to large products having high power, high efficiency, and high reliability. Therefore, there has been a need for light sources that have characteristics required for the corresponding products.

In general, a semiconductor junction light emitting device has a structure in which p-type and n-type semiconductors are bonded to each other. In the semiconductor junction structure, light may be emitted by recombination of electrons and holes at a region where the two types of semiconductors are bonded to each other. In order to activate the light emission, an active layer may be formed between the two semiconductors. The semiconductor junction light emitting device includes a horizontal structure and a vertical structure according to the position of electrodes of semiconductor layers. The vertical structure includes an epi-up structure and a flip-chip structure. As described above, structural characteristics of semiconductor light emitting devices that are required according to characteristics of individual products are seriously taken into account.

FIGS. 1A and 1B are views illustrating a horizontal light emitting device according to the related art.FIG. 1C is a cross-sectional view illustrating a vertical light emitting device according to the related art. Hereinafter, for the convenience of explanation, inFIGS. 1A to 1C, a description will be made on the assumption that an n-type semiconductor layer is in contact with a substrate, and a p-type semiconductor layer is formed on an active layer.

Referring toFIG. 1A, a horizontal light emitting device having an epi-up structure will be described first. InFIG. 1A, a description will be made on the assumption that a semiconductor layer formed at the outermost edge is a p-type semiconductor layer. A semiconductorlight emitting device1 includes anon-conductive substrate13, an n-type semiconductor layer12, anactive layer11, and a p-type semiconductor layer10. An n-type electrode15 and a p-type electrode14 are formed on the n-type semiconductor layer12 and the p-type semiconductor layer10, respectively, and are connected to an external current source (not shown) to apply a voltage to the semiconductorlight emitting device1.

When a voltage is applied to the semiconductorlight emitting device1 through theelectrodes14 and15, electrons move from the n-type semiconductor layer12, and holes move from the p-type semiconductor layer10. Light is emitted by recombination of the electrons and the holes. The semiconductorlight emitting device1 includes theactive layer11, and light is emitted from theactive layer11. In theactive layer11, the light emission of the semiconductorlight emitting device1 is activated, and light is emitted. In order to make an electrical connection, the n-type electrode and the p-type electrode are located on the n-type semiconductor layer12 and the p-type semiconductor layer10, respectively, with the lowest contact resistances.

The position of the electrodes may change according to the substrate type. For example, when thesubstrate13 is a sapphire substrate that is a non-conductive substrate, the electrode of the n-type semiconductor layer12 cannot be formed on thenon-conductive substrate13, but on the n-type semiconductor layer12.

Therefore, referring toFIG. 1A, when the n-type electrode15 is formed on the n-type semiconductor12, parts of the p-type semiconductor layer10 and theactive layer12 that are formed at the upper side are consumed to form an ohmic contact. The formation of the electrode results in a decrease of light emitting area of the semiconductorlight emitting device1, and thus luminous efficiency also decreases.

InFIG. 1B, a horizontal light emitting device has a structure that increases luminous efficiency is illustrated. The semiconductor light emitting device, shown inFIG. 1B, is a flip chip semiconductorlight emitting device2. Asubstrate23 is located at the top.Electrodes24 and25 are in contact withelectrode contacts26 and27, respectively, which are formed on aconductive substrate28. Light emitted from anactive layer21 is emitted through thesubstrate23 regardless of theelectrodes24 and25. Therefore, the decrease in luminous efficiency that is caused in the semiconductor light emitting device, shown inFIG. 1A, can be prevented.

However, despite the high luminous efficiency of the flip chiplight emitting device2, the n-type electrode and the p-type electrode in thelight emitting device2 need to be disposed in the same plane and bonded in the semiconductorlight emitting device2. After being bonded, the n-type electrode and the p-type electrode are likely to be separated from theelectrode contacts26 and27. Therefore, there is a need for expensive precision processing equipment. This causes an increase in manufacturing costs, a decrease in productivity, a decrease in yield, and a decrease in product reliability.

In order to solve a variety of problems including the above-described problems, a vertical light emitting device that uses a conductive substrate, not the non-conductive substrate, appeared. Alight emitting device3, shown inFIG. 1C, is a vertical light emitting device. When aconductive substrate33 is used, an n-type electrode35 may be formed on thesubstrate33. Theconductive substrate33 may be formed of a conductive material, for example, Si. In general, it is difficult to form semiconductor layers on the conductive substrate due to lattice-mismatching. Therefore, semiconductor layers are grown by using a substrate that allows easy growth of the semiconductor layers, and then a conductive substrate is bonded after removing the substrate for growth.

When the non-conductive substrate is removed, theconductive substrate33 is formed on the n-type semiconductor layer32, such that thelight emitting device3 has a vertical structure. When theconductive substrate33 is used, since a voltage can be applied to the n-type semiconductor layer32 through theconductive substrate33, an electrode can be formed on thesubstrate33. Therefore, as shown inFIG. 1C, the n-type electrode35 is formed on theconductive substrate33, and the p-type electrode34 is formed on the p-type semiconductor layer30, such that the semiconductor light emitting device having the vertical structure can be manufactured.

However, when a high-power light emitting device having a large area is manufactured, an area ratio of the electrode to the substrate needs to be high for current spreading. Therefore, light extraction is limited, light loss is caused by optical absorption, luminous efficiency decreases, and product reliability is reduced.

SUMMARY OF THE INVENTION

An aspect of the present invention provides to a semiconductor light emitting device that ensures a maximum light emitting area to maximize luminous efficiency and perform uniform current spreading by using an electrode having a small area, and enables mass production at low cost with high reliability and high quality, a method of manufacturing the same, and a semiconductor light emitting device package using the same.

According to an aspect of the present invention, there is provided a semiconductor light emitting device having a first conductivity type semiconductor layer, an active layer, a second conductivity type semiconductor layer, a second electrode layer, and insulating layer, a first electrode layer, and a conductive substrate sequentially laminated, wherein the second electrode layer has an exposed area at the interface between the second electrode layer and the second conductivity type semiconductor layer, and the first electrode layer comprises at least one contact hole electrically connected to the first conductivity type semiconductor layer, electrically insulated from the second conductivity type semiconductor layer and the active layer, and extending from one surface of the first electrode layer to at least part of the first conductivity type semiconductor layer.

The semiconductor light emitting device may further include an electrode pad unit formed at the exposed area of the second electrode layer.

The exposed area of the second electrode layer may be a region exposed by a via hole formed through the first conductivity type semiconductor layer, the active layer, and the second conductivity type semiconductor layer.

The diameter of the via hole may increase in a direction from the second electrode layer toward the first conductivity type semiconductor layer.

An insulating layer may be formed on an inner surface of the via hole.

The exposed area of the second electrode layer may be formed at the edge of the semiconductor light emitting device.

The second electrode layer may reflect light generated from the active layer.

The second electrode layer may include one metal selected from a group consisting of Ag, Al, and Pt.

An irregular pattern may be formed on the surface of the first conductivity type semiconductor layer.

The irregular pattern may have a photonic crystal structure.

The conductive substrate may include one metal selected from a group consisting of Au, Ni, Cu, and W.

The conductive substrate may include one selected from a group consisting of Si, Ge, and GaAs.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor light emitting device, the method including: sequentially laminating a first conductivity type semiconductor layer, an active layer, a second conductivity type semiconductor layer, a second electrode layer, an insulating layer, a first electrode layer, and a conductive substrate; forming an exposed area at the interface between the second electrode layer and the second conductivity type semiconductor layer; and forming at least one contact hole in the first electrode layer, the contact hole electrically connected to the first conductivity type semiconductor layer, electrically insulated from the second conductivity type semiconductor layer and the active layer, and extending from one surface of the first electrode layer to at least part of the first conductivity type semiconductor layer.

The forming an exposed area of the second electrode layer may include mesa etching the first conductivity type semiconductor layer, the active layer, and the second conductivity type semiconductor layer.

The conductive substrate may be formed by plating method and laminated. The conductive substrate may be laminated by a substrate bonding method.

According to still another aspect of the present invention, there is provided a semiconductor light emitting device package including: a semiconductor light emitting device package body having a recessed part formed at an upper surface thereof; a first lead frame and a second lead frame mounted to the semiconductor light emitting device package body, exposed at a lower surface of the recessed part, and separated from each other by a predetermined distance; a semiconductor light emitting device mounted to the first lead frame, wherein the semiconductor light emitting device has a first conductivity type semiconductor layer, an active layer, a second conductivity type semiconductor layer, a second electrode layer, an insulating layer, a first electrode layer, and a conductive substrate sequentially laminated, the second electrode layer comprises an exposed area at the interface between the second electrode layer and the second conductivity type semiconductor layer, and the first electrode layer comprises at least one contact hole electrically connected to the first conductivity type semiconductor layer, electrically insulated from the second conductivity type semiconductor layer and the active layer, and extending from one surface of the first electrode layer to at least part of the first conductivity type semiconductor layer.

The semiconductor light emitting device may further include an electrode pad unit formed at the exposed area of the second electrode layer, and the electrode pad unit is electrically connected to the second lead frame.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1A is a cross-sectional view illustrating a horizontal light emitting device.

FIG. 1B is a cross-sectional view illustrating the horizontal light emitting device.

FIG. 1C is a cross-sectional view illustrating a vertical light emitting device.

FIG. 2 is a perspective view illustrating a semiconductor light emitting device according to an exemplary embodiment of the present invention.

FIG. 3 is a plan view illustrating the semiconductor light emitting device shown inFIG. 2.

FIG. 4A is a cross-sectional view illustrating the semiconductor light emitting device, shown inFIG. 3, taken along the line A-A′.

FIG. 4B is a cross-sectional view illustrating the semiconductor light emitting device, shown inFIG. 3, taken along the line B-B′.

FIG. 4C is a cross-sectional view illustrating the semiconductor light emitting device, shown inFIG. 3, taken along the line C-C′.

FIG. 5 is a view illustrating light emission in the semiconductor light emitting device having an irregular pattern at the surface thereof according to the embodiment of the present invention.

FIG. 6 is a view illustrating a second electrode layer exposed at the edge of the semiconductor light emitting device according to another embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating a semiconductor light emitting package according to still another embodiment of the present invention.

FIG. 8 is a graph illustrating the relationship between luminous efficiency and current density of a light emitting surface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The invention may however be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

FIG. 2 is a perspective view illustrating a semiconductor light emitting device according to an exemplary embodiment of the invention.FIG. 3 is a plan view illustrating the semiconductor light emitting device shown inFIG. 2. Hereinafter, a description will be made with reference toFIGS. 2 and 3.

A semiconductorlight emitting device100 according to the exemplary embodiment of the invention includes a first conductivitytype semiconductor layer111, anactive layer112, a second conductivitytype semiconductor layer113, asecond electrode layer120, a first insulatinglayer130, afirst electrode layer140, and aconductive substrate150 that are sequentially laminated. At this time, thesecond electrode layer120 has an exposed area at the interface between thesecond electrode layer120 and the second conductivitytype semiconductor layer113. Thefirst electrode layer140 includes at least onecontact hole141. Thecontact hole141 is electrically connected to the first conductivitytype semiconductor layer111, electrically insulated from the second conductivitytype semiconductor layer113 and theactive layer112, and extends from one surface of thefirst electrode layer140 to at least part of the first conductivitytype semiconductor layer111.

In the semiconductorlight emitting device100, the first conductivitytype semiconductor layer111, theactive layer112, and the second conductivitytype semiconductor layer113 perform light emission. Hereinafter, they are referred to as alight emitting lamination110. That is, the semiconductorlight emitting device100 includes thelight emitting lamination110, thefirst electrode layer140, and the first insulatinglayer130. Thefirst electrode layer140 is electrically connected to the first conductivitytype semiconductor layer111. Thesecond electrode layer120 is electrically connected to the second conductivitytype semiconductor layer113. The first insulatinglayer130 electrically insulates the electrode layers120 and140 from each other. Further, theconductive substrate150 is included as a substrate to grow or support the semiconductorlight emitting device100.

Each of the semiconductor layers111 and113 may be formed of a semiconductor, such as a GaN-based semiconductor, a ZnO-based semiconductor, a GaAs-based semiconductor, a GaP-based semiconductor, and a GaAsP-based semiconductor. The semiconductor layer may be formed by using, for example, molecular beam epitaxy (MBE). In addition, each of the semiconductor layers may be formed of any one of semiconductors, such as a III-V semiconductor, a II-VI semiconductor, and Si. Each of the semiconductor layers111 and113 is formed by doping the above-described semiconductor with appropriate impurities in consideration of the conductivity type.

Theactive layer112 is a layer where light emission is activated. Theactive layer112 is formed of a material that has a smaller energy bandgap than each of the first conductivitytype semiconductor layer111 and the second conductivitytype semiconductor layer113. For example, when each of the first conductivitytype semiconductor layer111 and the second conductivitytype semiconductor layer113 is formed of a GaN-based compound, theactive layer112 may be formed by using an InAlGaN-based compound semiconductor that has a smaller energy bandgap than GaN. That is, theactive layer112 may include In_xAl_yGa_(1-x-y)N (0≤x≤1, 0≤y≤1, 0≤x+y≤1).

In consideration of characteristics of theactive layer112, theactive layer120 is preferably not doped with impurities. A wavelength of light emitted can be controlled by adjusting a mole ratio of constituents. Therefore, the semiconductorlight emitting device100 can emit any one of infrared light, visible light, and UV light according to the characteristics of theactive layer112.

Each of the electrode layers120 and140 is formed in order to apply a voltage to the same conductivity type semiconductor layer. Therefore, in consideration of electroconductivity, the electrode layers120 and140 may be formed of metal. That is, the electrode layers120 and140 include electrodes that electrically connect the semiconductor layers111 and113 to an external current source (not shown). The electrode layers120 and140 may include, for example, Ti as an n-type electrode, and Pd or Au as a p-type electrode.

Thefirst electrode layer140 is connected to the first conductivitytype semiconductor layer111, and thesecond electrode layer120 is connected to the second conductivitytype semiconductor layer113. That is, since the first andsecond layers140 and120 are connected to the different conductivity type semiconductor layers from each other, the first andsecond layers140 and120 are electrically separated from each other by the first insulatinglayer130. Preferably, the first insulatinglayer130 is formed of a material having low electroconductivity. The first insulatinglayer130 may include, for example, an oxide such as SiO₂.

Preferably, thesecond electrode layer120 reflects light generated from theactive layer112. Since thesecond electrode layer120 is located below theactive layer112, thesecond electrode layer120 is located at the other side of a direction in which the semiconductorlight emitting device100 emits light on the basis of theactive layer112. Light moving from theactive layer112 toward thesecond electrode layer120 is in an opposition direction to the direction in which the semiconductorlight emitting device100 emits light. Therefore, the light proceeding toward thesecond electrode layer120 needs to be reflected to increase luminous efficiency. Therefore, when thesecond electrode layer120 has light reflectivity, the reflected light moves toward a light emitting surface to thereby increase the luminous efficiency of the semiconductorlight emitting device100.

In order to reflect the light generated from theactive layer112, preferably, thesecond electrode layer120 is formed of metal that appears white in the visible ray region. For example, the white metal may be any one of Ag, Al, and Pt.

Thesecond electrode layer120 includes an exposed area at the interface between thesecond electrode layer120 and the second conductivitytype semiconductor layer113. A lower surface of thefirst electrode layer140 is in contact with theconductive substrate150, and thefirst electrode layer140 is electrically connected to the external current source (not shown) through theconductive substrate150. However, thesecond electrode layer120 requires a separate connecting region so as to be connected to the external current source (not shown). Therefore, thesecond electrode layer120 includes an area that is exposed by partially etching thelight emitting lamination110.

InFIG. 2, an example of a viahole114 is shown. The viahole114 is formed by etching the center of thelight emitting lamination110 to form an exposed area of thesecond electrode layer120. Anelectrode pad unit160 may be further formed at the exposed area of thesecond electrode layer120. Thesecond electrode layer120 can be electrically connected to the external power source (not shown) by the exposed region thereof. At this time, thesecond electrode layer120 is electrically connected to the external power source (not shown) by using theelectrode pad unit160. Thesecond electrode layer120 can be electrically connected to the external current source (not shown) by a wire or the like. For convenient connection to the external current source, preferably, the diameter of the via hole increases from the second electrode layer toward the first conductivity type semiconductor layer.

The viahole114 is formed by selective etching. In general, thelight emitting lamination110 including the semiconductors is only etched, and thesecond electrode layer120 including the metal is not etched. The diameter of the viahole114 can be appropriately determined by those skilled in the art in consideration of the light emitting area, electrical connection efficiency, and current spreading in thesecond electrode layer120.

Thefirst electrode layer140 includes at least onecontact hole141. Thecontact hole141 is electrically connected to the first conductivitytype semiconductor layer111, electrically insulated from the second conductivitytype semiconductor layer113 and theactive layer112, and extends to at least part of the first conductivitytype semiconductor layer111. Thefirst electrode layer140 includes at least onecontact hole141 in order to connect the first conductivitytype semiconductor layer111 to the external current source (not shown). Thecontact hole141 is formed through thesecond electrode layer120 between thefirst electrode layer140 and the second conductivitytype semiconductor layer113, the second conductivitytype semiconductor layer113, and theactive layer112, and extends to the first conductivitytype semiconductor layer111. Further, thecontact hole141 is formed of an electrode material.

When thecontact hole141 is only used for the electrical connection, thefirst electrode layer140 may include onecontact hole141. However, in order to uniformly spread a current that is transmitted to the first conductivitytype semiconductor layer111, thefirst electrode layer140 may include a plurality ofcontact holes141 at predetermined positions.

Theconductive substrate150 is formed in contact with and is electrically connected to thefirst electrode layer140. Theconductive substrate150 may be a metallic substrate or a semiconductor substrate. When theconductive substrate150 is formed of metal, the metal may be any one of Au, Ni, Cu, and W. Further, when theconductive substrate150 is the semiconductor substrate, the semiconductor substrate may be formed of any one of Si, Ge, and GaAs. Theconductive substrate150 may be a growth substrate. Alternatively, theconductive substrate150 may be a supporting substrate. After a non-conductive substrate, such as a sapphire substrate having small lattice-mismatching, is used as a growth substrate, and the non-conductive substrate is removed, the supporting substrate is bonded.

When theconductive substrate150 is the supporting substrate, it may be formed by using a plating method or a substrate bonding method. Specifically, examples of a method of forming theconductive substrate150 in the semiconductorlight emitting device100 may include a plating method of forming a plating seed layer to forma substrate and a substrate bonding method of separately preparing theconductive substrate150 and bonding theconductive substrate150 by using a conductive adhesive, such as Au, Au—Sn, and Pb—Sr.

FIG. 3 is a plan view illustrating the semiconductorlight emitting device100. The viahole114 is formed in an upper surface of the semiconductorlight emitting device100, and theelectrode pad unit160 is positioned at the exposed region of thesecond electrode layer120. In addition, though not shown in the upper surface of the semiconductorlight emitting device100, in order to display the positions of the contact holes141, the contact holes141 are shown as a dotted line to display the positions of the contact holes141. The first insulatinglayer130 may extend and surround thecontact hole141 so that thecontact hole141 is electrically separated from thesecond electrode layer120, the second conductivitytype semiconductor layer113, and theactive layer112. This will be described in more detail with reference toFIGS. 4B and 4C.

FIG. 4A is a cross-sectional view illustrating the semiconductor light emitting device, shown inFIG. 3, taken along the line A-A′.FIG. 4B is a cross-sectional view illustrating the semiconductor light emitting device, shown inFIG. 3, taken along the line B-B′.FIG. 4C is a cross-sectional view illustrating the semiconductor light emitting device, shown inFIG. 3, taken along the line C-C′. The line A-A′ is taken to show a cross section of the semiconductorlight emitting device100. The line B-B′ is taken to show a cross section that includes the contact holes141 and the viahole114. The line C-C′ is taken to show a cross section that only includes the contact holes141. Hereinafter, the description will be described with reference toFIGS. 4A to 4C.

With reference toFIG. 4A, neither thecontact hole141 nor the viahole114 is shown. Since thecontact hole141 is not connected by using a separate connecting line but electrically connected by thefirst electrode layer140, thecontact hole141 is not shown in the cross section inFIG. 3.

Referring toFIGS. 4B and 4C, thecontact hole141 extends from the interface between thefirst electrode layer140 and thesecond electrode layer120 to the inside of the first conductivitytype semiconductor layer111. Thecontact hole141 passes through the second conductivitytype semiconductor layer113 and theactive layer112 and extends to the first conductivitytype semiconductor layer111. Thecontact hole141 extends at least to the interface between theactive layer112 and the first conductivitytype semiconductor layer111. Preferably, thecontact hole141 extends to part of the first conductivitytype semiconductor layer111. However, thecontact hole141 is used for the electrical connection and current spreading. Once thecontact hole141 is in contact with the first conductivitytype semiconductor layer111, thecontact hole141 does not need to extend to the outer surface of the first conductivitytype semiconductor layer111.

Thecontact hole141 is formed to spread the current in the first conductivitytype semiconductor layer111. Therefore, a predetermined number of contact holes141 are formed, and each of the contact holes141 has an area small enough to allow uniform current spreading in the first conductivitytype semiconductor layer111. A small number of contact holes141 may cause deterioration in electrical characteristics due to difficulties in performing current spreading. A large number of contact holes141 may cause difficulties in forming the contact holes141 and a reduction in light emitting area due to a decrease in area of the active layer. Therefore, each of the contact holes141 is formed to have as small area as possible and allow uniform current spreading.

Thecontact hole141 extends from thesecond electrode layer120 to the inside of the first conductivitytype semiconductor layer111. Since thecontact hole141 is formed to spread the current in the first conductivity type semiconductor layer, thecontact hole141 needs to be electrically separated from the second conductivitytype semiconductor layer113 and theactive layer112. Therefore, preferably, thecontact hole141 is electrically separated from thesecond electrode layer120, the second conductivitytype semiconductor layer113, and theactive layer112. Therefore, the first insulatinglayer130 may extend while surrounding thecontact hole141. The electrical separation may be performed by using an insulating material, such as a dielectric.

InFIG. 4B, the exposed region of thesecond electrode layer120 is formed so that thesecond electrode layer120 is electrically connected to the external current source (not shown). Theelectrode pad unit160 may be positioned at the exposed region. At this time, a second insulatinglayer170 may be formed on an inner surface of the viahole114 so that thelight emitting lamination110 and theelectrode pad unit160 can be electrically separated from each other.

As shown inFIG. 4A, since thefirst electrode layer140 and thesecond electrode layer120 are formed in the same plane, the semiconductorlight emitting device100 has characteristics of the horizontal semiconductorlight emitting device100. As shown inFIG. 4B, since theelectrode pad unit160 is formed at the surface of the second conductivitytype semiconductor layer120, the semiconductorlight emitting device100 can have characteristics of the vertical light emitting device. Therefore, the semiconductorlight emitting device100 has a structure into which the vertical structure and the horizontal structure are integrated.

InFIGS. 4A to 4C, the first conductivitytype semiconductor layer111 may be an n-type semiconductor layer, and thefirst electrode layer140 may be an n-type electrode. In this case, the second conductivitytype semiconductor layer113 may be a p-type semiconductor layer, and thesecond electrode layer120 may be a p-type electrode. Therefore, thefirst electrode layer140 formed of the n-type electrode and thesecond electrode layer120 formed of the p-type electrode may be electrically insulated from each other with the first insulatinglayer130 interposed therebetween.

FIG. 5 is a view illustrating light emission in a semiconductor light emitting device having an irregular pattern formed at the surface thereof according to an exemplary embodiment of the present invention. The description of the same components that have already been described will be omitted.

In the semiconductorlight emitting device100 according to the exemplary embodiment of the invention, the first conductivitytype semiconductor layer111 forms the outermost edge in a direction in which emitted light moves. Therefore, anirregular pattern180 can be easily formed on the surface by using a known method, such as photolithography. In this case, the light emitted from theactive layer112 passes through theirregular pattern180 formed at the surface of the first conductivitytype semiconductor layer111, and then the light is extracted. Theirregular pattern180 results in an increase in light extraction efficiency.

Theirregular pattern180 may have a photonic crystal structure. Photonic crystals contain different media that have different refractive indexes and are regularly arranged like crystals. The photonic crystals can increase light extraction efficiency by controlling light in unit of length corresponding to a multiple of a wavelength of light.

FIG. 6 is a view illustrating a second electrode layer exposed at the edge of a semiconductor light emitting device according to another exemplary embodiment of the present invention.

According to another exemplary embodiment of the present invention, a method of manufacturing a semiconductor light emitting device is provided. The method includes sequentially laminating a first conductivitytype semiconductor layer211, anactive layer212, a second conductivitytype semiconductor layer213, asecond electrode layer220, an insulatinglayer230, afirst electrode layer240, and aconductive substrate250; forming an exposed area at the interface between thesecond electrode layer220 and the second conductivitytype semiconductor layer213; and forming at least one contact hole241 in the second conductivitytype semiconductor layer213, the contact hole241 electrically connected to the first conductivitytype semiconductor layer211, electrically insulated from the second conductivitytype semiconductor layer213 and theactive layer212, and extending from one surface of thefirst electrode layer240 to at least part of the first conductivitytype semiconductor layer211.

At this time, the exposed area of thesecond electrode layer220 may be formed by forming the viahole214 in a light emitting lamination210 (refer toFIG. 2). Alternatively, as shown inFIG. 6, the exposed area of thesecond electrode layer220 may be formed by mesa etching thelight emitting lamination210. In this embodiment, the description of the same components as those of the embodiment that has been described with reference to 2 will be omitted.

Referring toFIG. 6, one edge of a semiconductorlight emitting device200 is mesa etched. A corner of the semiconductorlight emitting device200 is etched to expose thesecond electrode layer220 at the interface between thesecond electrode layer220 and the second conductivitytype semiconductor layer213. The exposed area of thesecond electrode layer220 is formed at the corner of the semiconductorlight emitting device200. A process of forming the exposed region at the corner of the semiconductorlight emitting device200 is simpler than the process of forming the via hole in the above-described embodiment, and also allows a subsequent process of electrical connection to be easily performed.

FIG. 7 is a cross-sectional view illustrating a semiconductor light emittingdevice package300 according to still another embodiment of the present invention. The semiconductor light emittingdevice package300 includes a semiconductor light emittingdevice package body360a,360b, and360c having an upper surface in which a recessed part is formed, afirst lead frame370a and asecond lead frame370b mounted to the semiconductor light emittingdevice package body360a,360b, and360c, exposed at a lower surface of the recessed part, and separated from each other by a predetermined distance, and a semiconductorlight emitting device310 and320 mounted to thefirst lead frame370a. The semiconductorlight emitting device310 and320 is the semiconductor light emitting device having the via hole at the center thereof according to the exemplary embodiment of the invention that has been described with reference toFIG. 2. The description of the same components having been described will be omitted.

The semiconductorlight emitting device310 and320 includes alight emitting unit310 and aconductive substrate320. Thelight emitting unit310 includes first and second semiconductor layers, an active layer, and electrode layers. A via hole is formed in thelight emitting unit310, and the semiconductorlight emitting device310 and320 further includes anelectrode pad unit330 at an exposed region. Theconductive substrate320 is electrically connected to thefirst lead frame370a, and theelectrode pad unit330 is electrically connected to thesecond lead frame370b by awire340 or the like.

The semiconductorlight emitting device310 and320 is electrically connected to thesecond lead frame370b, to which the semiconductorlight emitting device310 and320 is not mounted, bywire bonding340. Therefore, the semiconductor light emitting device can obtain high luminous efficiency and has a vertical structure. As shown inFIG. 7, the semiconductor light emitting device is mounted to thelead frame370a by die bonding and to thelead frame370b by wire bonding. Therefore, the process can be performed at relatively low costs.

FIG. 8 is a graph illustrating the relationship between luminous efficiency and current density of a light emitting surface. When current density is about 10 A/cm²or more, if the current density is low, luminous efficiency is high, and if the current density is high, luminous efficiency is low.

The relationship between the current density and the luminous efficiency, and light emitting area are numerically shown in Table 1.

TABLE 1
			Luminous
	Light emitting	Current density	efficiency	Improvement
	area (cm2)	(A/cm2)	(lm/W)	(%)
	0.0056	62.5	46.9	100
	0.0070	50.0	51.5	110
	0.0075	46.7	52.9	113
	0.0080	43.8	54.1	115

Referring toFIG. 8 and Table 1, as the light emitting area increases, luminous efficiency increases. However, in order to ensure the light emitting area, the area of the distributed electrodes needs to be reduced, which reduces current density of the light emitting surface. The reduction in current density of the light emitting surface may deteriorate electrical characteristics of the semiconductor light emitting device.

However, this problem can be solved by ensuring current spreading by using contact holes according to the embodiments of the invention. Therefore, the deterioration in electrical characteristics that may be caused by the reduction in current density can be prevented by using a method of forming contact holes in the semiconductor light emitting device that do not extend to the light emitting surface for current spreading but are formed therein. Therefore, the semiconductor light emitting device according to the embodiments of the invention performs desired current spreading and ensures a maximum light emitting area to obtain desirable luminous efficiency.

As set forth above, according to exemplary embodiments of the invention, the semiconductor light emitting device can prevent emitted light from being reflected or absorbed by electrodes and ensure the maximum light emitting area by forming the electrodes of semiconductor layers, located in a light emitting direction, below an active layer except for part of the electrodes, thereby maximizing luminous efficiency.

Further, at least one contact hole is formed in the electrode to smoothly perform current spreading, such that uniform current spreading can be performed with the electrode having a small area.

Further, since the via hole is formed at the upper surface of the semiconductor light emitting device, alignment is not required during die bonding, and wire bonding can be easily performed. In addition, since the semiconductor light emitting device has a vertical structure, wire bonding and die bonding that can be easily performed at low cost can be used together when manufacturing a package. Therefore, mass production can be achieved at low cost.

Therefore, according to the embodiments of the invention, mass production of light emitting devices at low cost with high reliability and high quality can be realized.

While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (30)

What is claimed is:

1. A semiconductor light emitting device having a first conductivity type semiconductor layer, an active layer, a second conductivity type semiconductor layer, a second electrode layer, and insulating layer, a first electrode layer, and a conductive substrate sequentially laminated, wherein:

the second electrode layer has an exposed area at an interface between the second electrode layer and the second conductivity type semiconductor layer,

the first electrode layer comprises at least one contact hole electrically connected to the first conductivity type semiconductor layer, electrically insulated from the second conductivity type semiconductor layer and the active layer, and extending from one surface of the first electrode layer to at least part of the first conductivity type semiconductor layer, and

an irregular pattern is defined on a surface of the first conductivity type semiconductor layer.

2. The semiconductor light emitting device ofclaim 1, further comprising an electrode pad unit formed at the exposed area of the second electrode layer.

3. The semiconductor light emitting device ofclaim 1,

wherein the exposed area of the second electrode layer is a region exposed by a via hole formed through the first conductivity type semiconductor layer, the active layer, and the second conductivity type semiconductor layer.

4. The semiconductor light emitting device ofclaim 3, wherein the diameter of the via hole increases in a direction from the second electrode layer toward the first conductivity type semiconductor layer.

5. The semiconductor light emitting device ofclaim 3, wherein an insulating layer is formed on an inner surface of the via hole.

6. The semiconductor light emitting device ofclaim 1, wherein the exposed area of the second electrode layer is formed at the edge of the semiconductor light emitting device.

7. The semiconductor light emitting device ofclaim 1, wherein the second electrode layer reflects light generated from the active layer.

8. The semiconductor light emitting device ofclaim 7, wherein the second electrode layer comprises one metal selected from a group consisting of Ag, Al, and Pt.

9. The semiconductor light emitting device ofclaim 1, wherein the irregular pattern has a photonic crystal structure.

10. The semiconductor light emitting device ofclaim 1, wherein the conductive substrate comprises one metal selected from a group consisting of Au, Ni, Cu, and W.

11. The semiconductor light emitting device ofclaim 1, wherein the conductive substrate comprises one selected from a group consisting of Si, Ge, and GaAs.

12. The semiconductor light emitting device ofclaim 1, wherein the irregular pattern is defined on an edge of the semiconductor light emitting device, which is an outermost edge in a direction in which light is emitted from the semiconductor light emitting device.

13. A method of manufacturing a semiconductor light emitting device, the method comprising:

sequentially laminating a first conductivity type semiconductor layer, an active layer, a second conductivity type semiconductor layer, a second electrode layer, an insulating layer, a first electrode layer, and a conductive substrate;

forming an exposed area at an interface between the second electrode layer and the second conductivity type semiconductor layer; and

forming at least one contact hole in the first electrode layer, the contact hole electrically connected to the first conductivity type semiconductor layer, electrically insulated from the second conductivity type semiconductor layer and the active layer, and extending from one surface of the first electrode layer to at least part of the first conductivity type semiconductor layer,

wherein the forming of the exposed area of the second electrode layer comprises mesa etching the first conductivity type semiconductor layer, the active layer, and the second conductivity type semiconductor layer.

14. The method ofclaim 13, wherein the conductive substrate is formed by a plating method and laminated.

15. The method ofclaim 13, wherein the conductive substrate is laminated by a substrate bonding method.

16. The method ofclaim 13, wherein the forming of the exposed area includes etching a corner of the semiconductor light emitting device to expose the second electrode layer at the interface between the second electrode layer and the second conductivity type semiconductor layer.

17. A semiconductor light emitting device package comprising:

a semiconductor light emitting device package body having a recessed part defined at an upper surface thereof;

a first lead frame and a second lead frame disposed on the semiconductor light emitting device package body, exposed at a lower surface of the recessed part, and separated from each other by a predetermined distance;

a semiconductor light emitting device disposed on the first lead frame, wherein:

the semiconductor light emitting device comprises a first conductivity type semiconductor layer, an active layer, a second conductivity type semiconductor layer, a second electrode layer, an insulating layer, a first electrode layer, and a conductive substrate sequentially laminated,

the second electrode layer comprises an exposed area at an interface between the second electrode layer and the second conductivity type semiconductor layer,

the first electrode layer comprises at least one contact hole electrically connected to the first conductivity type semiconductor layer, electrically insulated from the second conductivity type semiconductor layer and the active layer, and extending from one surface of the first electrode layer to at least part of the first conductivity type semiconductor layer, and

the semiconductor light emitting device further comprises an electrode pad unit disposed at the exposed area of the second electrode layer, and the electrode pad unit is electrically connected to the second lead frame.

18. The method ofclaim 17, wherein a portion of the semiconductor light emitting device package body is exposed at the lower surface of the recess part between the first lead frame and the second lead frame.

19. A semiconductor light emitting device comprising:

a substrate;

a first electrode layer disposed on the substrate;

a first insulating layer disposed on the first electrode layer;

a second electrode layer disposed on the first insulating layer and including an exposed surface;

a second conductivity type semiconductor layer disposed on the second electrode layer;

an active layer disposed on the second conductivity type semiconductor layer; and

a first conductivity type semiconductor layer disposed on the active layer and including an irregular pattern on a surface of the first conductivity type semiconductor layer,

wherein the first electrode layer includes at least one protruding portion that extends to the first conductivity type semiconductor layer and is electrically connected to the first conductivity type semiconductor layer.

20. The semiconductor light emitting device of claim 19, wherein the at least one protruding portion is electrically insulated from the second electrode layer, the active layer and the second conductivity type semiconductor layer.

21. The semiconductor light emitting device of claim 19, wherein the exposed surface is exposed through the second conductivity type semiconductor layer, the active layer and the first conductivity type semiconductor layer.

22. The semiconductor light emitting device of claim 19, wherein the exposed surface is formed at an edge of the semiconductor light emitting device.

23. The semiconductor light emitting device of claim 21, wherein the exposed surface is exposed through an opening that is obliquely formed through the second conductivity type semiconductor layer, the active layer and the first conductivity type semiconductor layer.

24. A semiconductor light emitting device comprising:

a substrate;

a first electrode layer disposed on the substrate;

a first insulating layer disposed on the first electrode layer;

a second electrode layer disposed on the first insulating layer and including an exposed surface;

a second conductivity type semiconductor layer disposed on the second electrode layer;

an active layer disposed on the second conductivity type semiconductor layer;

a first conductivity type semiconductor layer disposed on the active layer and including an irregular pattern on a surface of the first conductivity type semiconductor layer; and

at least one contact layer extending from the first electrode layer to the first conductivity type semiconductor layer and electrically connecting the first conductivity type semiconductor layer to the first electrode layer.

25. The semiconductor light emitting device of claim 24, wherein the first electrode layer includes the at least one contact layer.

26. A semiconductor light emitting device comprising:

a substrate;

a first electrode layer disposed on the substrate;

a first insulating layer disposed on the first electrode layer;

a second electrode layer disposed on the first insulating layer;

a second conductivity type semiconductor layer disposed on the second electrode layer;

an active layer disposed on the second conductivity type semiconductor layer; and

a first conductivity type semiconductor layer disposed on the active layer,

wherein the first electrode layer includes at least one protruding portion that extends to the first conductivity type semiconductor layer and is electrically connected to the first conductivity type semiconductor layer, and

the second electrode layer includes a first surface that is partially exposed through the second conductivity type semiconductor layer, the active layer and the first conductivity type semiconductor layer.

27. The semiconductor light emitting device of claim 26, wherein the first conductivity type semiconductor layer includes an irregular pattern on a surface of the first conductivity type semiconductor layer.

28. A semiconductor light emitting device comprising:

a first electrode layer;

a first insulating layer disposed on the first electrode layer;

a second electrode layer disposed on the first insulating layer and including an exposed surface;

a second conductivity type semiconductor layer disposed on the second electrode layer;

an active layer disposed on the second conductivity type semiconductor layer; and

a first conductivity type semiconductor layer disposed on the active layer and including an irregular pattern on a surface of the first conductivity type semiconductor layer,

wherein the first electrode layer includes at least one protruding portion that extends to the first conductivity type semiconductor layer, and

the at least one protruding portion is electrically connected to the first conductivity type semiconductor layer, and is electrically insulated from the second electrode layer, the active layer and the second conductivity type semiconductor layer.

29. The semiconductor light emitting device of claim 28, further comprising a substrate on which the first electrode layer is disposed.

30. A semiconductor light emitting device package comprising:

a package body;

a first lead frame and a second lead frame mounted on the package body; and

a semiconductor light emitting device disposed on the first lead frame, and including:

a first electrode layer;

a first insulating layer disposed on the first electrode layer;

a second electrode layer disposed on the first insulating layer and including an exposed surface;

an electrode pad unit electrically connected to the second lead frame and disposed on the exposed surface of the second electrode layer;

a second conductivity type semiconductor layer disposed on the second electrode layer;

an active layer disposed on the second conductivity type semiconductor layer; and

a first conductivity type semiconductor layer disposed on the active layer and including an irregular pattern on a surface of the first conductivity type semiconductor layer,

wherein the first electrode layer includes at least one protruding portion that extends to the first conductivity type semiconductor layer, and

wherein the at least one protruding portion is electrically connected to the first conductivity type semiconductor layer, and is electrically insulated from the second electrode layer, the active layer and the second conductivity type semiconductor layer.

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