WO2015184773A1 - Light-emitting diode chip and manufacturing method therefor - Google Patents

Abstract

Provided are a light-emitting diode chip and a manufacturing method therefor. The light-emitting diode chip is provided with a light-emitting epitaxial stack layer and comprises at least a first semiconductor layer, a light-emitting layer and a second semiconductor layer in sequence, wherein the second semiconductor layer is set into a structure having an inclined side wall or a bulge structure having an inclined side edge; and then, a top surface thereof is cladded in a transparent conducting layer, and the transparent conducting layer extends to the inclined side wall/side edge thereof, so that the contact area of the transparent conducting layer and the inclined side wall/side edge can be increased, and with respect to a conventional planar structure, the contact area thereof is effectively increased, thereby contributing to the reduction of an operating voltage of a light-emitting diode. In addition, when light rays radiated from the light-emitting layer in the epitaxial stack layer meet with a metal extending electrode with the structure having an inclined side wall (the transparent conducting layer), in accordance with an incidence-reflection principle, the light rays are reflected to the side wall, thereby increasing the light extraction rate of an LED assembly.

Description

Light-emitting diode chip and manufacturing method thereof

The present application claims priority to Chinese Patent Application No. 2014-1024150, filed on Jun. 3, 2014, the entire disclosure of which is hereby incorporated by reference. .

Technical field

The invention relates to an LED chip, and more particularly to an LED chip structure having an obliquely extending electrode and a manufacturing method thereof.

Background technique

A Light Emitting Diode (LED) is a semiconductor diode that converts electrical energy into light energy with a PN junction under positive bias. In recent years, LEDs have been widely used, playing an increasingly important role in various display systems, lighting systems, automotive taillights and other fields. A typical light emitting diode structure can include an n-type electrode and an n-type layer, a substrate, multiple or single quantum well regions, a p-type layer, and a p-type electrode. After the positive bias is applied, most of the light generated in the quantum well region is absorbed by the semiconductor material or the substrate after a plurality of total reflections, so that the absorption loss inside the LED is greatly changed, and the light extraction rate of the component is greatly reduced. Therefore, for this conventional LED structure, even if the internal photoelectric conversion efficiency is high, its external quantum efficiency is not high. There are currently many ways to improve the extraction efficiency of LED light, such as thick window layer, surface roughening, transparent substrate, inverted pyramid structure.

Summary of the invention

The invention provides an LED chip and a manufacturing method thereof, which can increase an ohmic contact area between an electrode and an epitaxial layer, reduce a forward working voltage, and effectively improve the light extraction efficiency of the device.

According to a first aspect of the invention, an LED chip includes: a first semiconductor layer having a first region and a second region; and a light emitting layer formed on the first region of the first semiconductor layer a second semiconductor layer formed on the light-emitting layer, having a top surface, a bottom surface and an inclined sidewall, the inclined sidewall forming an acute angle with the bottom surface of the inner side of the second semiconductor layer; a transparent conductive layer Forming on a top surface of the portion of the second semiconductor layer and extending to the inclined sidewall of the second semiconductor layer; a first electrode and a second electrode are respectively formed on the second region of the first semiconductor layer Upper and transparent conductive layers.

According to a second aspect of the invention, a light emitting diode chip includes: a first semiconductor layer; a light emitting layer formed on the first semiconductor layer; and a second semiconductor layer formed on the light emitting layer It has several protrusions, and The protrusion has a top surface, a bottom surface and at least one inclined side edge, the inclined side edge forms an acute angle with the inner side of the bottom surface; a transparent conductive layer is formed on a top surface of the portion of the protrusion and extends to the An elevated side of the protrusion; an electrode is formed on the transparent conductive layer.

According to a third aspect of the invention, a method for fabricating an LED chip includes: providing a substrate; forming a light emitting epitaxial layer on the substrate, the method comprising at least a first semiconductor layer, a light emitting layer, and a second a semiconductor layer, wherein the first semiconductor layer has a first region and a second region; etching down from the surface of the second semiconductor to the first semiconductor layer by an etching process, so that a portion of the first semiconductor layer is exposed Coming out, that is, the second region is exposed, and the light emitting layer is located on the first region of the first semiconductor layer; forming the second semiconductor by an etching process or laser cutting or a knife cutting or any combination of the foregoing An inclined sidewall forming an acute angle with a bottom surface of the inner side of the second semiconductor layer; depositing a transparent conductive layer on a top surface of the portion of the second semiconductor layer and extending to the inclined sidewall of the second semiconductor layer And forming a first electrode and a second electrode on the second region of the first semiconductor layer and the transparent conductive layer, respectively.

According to a fourth aspect of the invention, a method for fabricating an LED chip includes: providing a substrate; forming an emissive epitaxial stack on the substrate, the method comprising at least a first semiconductor layer, a light emitting layer, and a second a semiconductor layer; formed by the etching process or laser cutting or dicing cutting or any combination of the foregoing, having a plurality of protrusions on the second semiconductor layer, and having the protrusions have a top surface, a bottom surface, and at least An inclined side edge, that is, the inclined side edge forms an acute angle with the inner side of the bottom surface; at least the top surface of the partially convex portion forms a transparent conductive layer and extends to the inclined side edges of the protrusion; An electrode is fabricated on the layer.

In some embodiments, the region sandwiched between the bumps is defined as a channel, and a transparent conductive layer is also formed on the trench.

In some embodiments, a buffer layer may also be formed on the substrate prior to forming the light-emitting epitaxial stack.

In some embodiments, the acute angle is preferably between 15 and 75 degrees.

In some embodiments, the transparent conductive layer may be a metal electrode such as AuZn, AuBe, CrAu or the like which can be in ohmic contact with the semiconductor, or a non-metal electrode such as ITO, IZO, GZO or the like.

In some embodiments, the transparent conductive layer extends to the inclined sidewall or the inclined side of the second semiconductor layer, which can effectively increase the ohmic contact area and reduce the operating voltage of the LED.

In some embodiments, the sloped sides of the protrusions are parallel to each other.

In some embodiments, the etching process is selected from dry etching or wet etching or a combination of the foregoing.

The foregoing light-emitting diode chip can be applied to various display systems, lighting systems, automobile taillights and the like.

Other features and advantages of the invention will be set forth in the description which follows,

DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are intended to be a In addition, the drawing figures are a summary of the description and are not drawn to scale.

1 is a cross-sectional view showing the structure of an LED chip of Embodiment 1.

2 is a plan view showing the structure of an LED chip of Embodiment 1.

3 is a cross-sectional view showing the structure of an LED chip of Embodiment 2.

4 is a plan view showing the structure of an LED chip of Embodiment 2.

Fig. 5 is a cross-sectional view showing the structure of a light-emitting diode chip of the third embodiment.

Fig. 6 is a plan view showing the structure of the light-emitting diode chip of the third embodiment.

7-12 are process flow diagrams of fabricating an LED chip of Embodiment 4.

Graphical description

Substrate 101, 201, 301, 401; first semiconductor layers 102, 202, 302, 402; luminescent layers 103, 203, 303, 403; second semiconductor layers 104, 204, 304, 404; transparent conductive layers 105, 205, 305, 405; first electrodes 106, 206, 306, 406; second electrodes 107, 207, 307, 407; protrusions 208, 308, 408.

detailed description

The LED device structure and the preparation method thereof according to the present invention will be described in detail below with reference to the schematic diagram, thereby how to apply the technical means to solve the technical problem, and realize the realization process of the technical effect can be fully understood and implemented. It should be noted that the various embodiments of the present invention and the various features of the various embodiments may be combined with each other, and the technical solutions formed are all within the scope of the present invention.

Example 1

Referring to FIG. 1 and FIG. 2, the LED chip of the present embodiment includes: a substrate 101 for epitaxial growth, a first semiconductor layer 102, a light-emitting layer 103, a second semiconductor layer 104 having inclined sidewalls, and a transparent conductive layer 105. The first electrode 106 and the second electrode 107.

Specifically, the epitaxial growth substrate 101 may be a non-conductive substrate such as Al ₂ O ₃ , AlN, PCB or MCPCB, or a Si conductive substrate, and sapphire (Al ₂ O ₃ ) is preferred in this embodiment.

The light emitting epitaxial layer is formed on the substrate 101. The first semiconductor layer 102, the light emitting layer 103 and the second semiconductor layer 104 are sequentially arranged from bottom to top, wherein the first semiconductor layer 102 is an N-type semiconductor coating layer having a a first region and a second region; the light emitting layer 103 is a multiple quantum well structure; and the second semiconductor layer 104 is a P type semiconductor having inclined sidewalls The body overcoat, in some variant embodiments, may also include a growth buffer layer prior to growing the luminescent epitaxial stack.

In this embodiment, the first semiconductor 102 is formed on the first region; the second semiconductor layer 104 is formed on the light-emitting layer 103, and has a top surface, a bottom surface, and a slant sidewall, wherein the slant sidewall and the second sidewall The bottom surface of the inner side of the semiconductor layer forms an acute angle θ, which may be between 15 and 75 degrees, preferably 45 degrees in this embodiment.

The transparent conductive layer 105 is formed on the top surface of the portion of the second semiconductor layer 104 and extends to the inclined sidewalls thereof, so that the ohmic contact area can be effectively increased and the operating voltage of the LED can be reduced.

In this embodiment, the transparent conductive layer 105 may be a metal electrode such as AuZn, AuBe, CrAu or the like which can form an ohmic contact with the semiconductor, or a non-metal electrode such as ITO, IZO or GZO, and the transparent conductive layer 105 is preferably an IZO material. As an extension electrode of the subsequent metal electrode.

The first electrode 106 and the second electrode 107 are respectively formed on the second region of the first semiconductor layer 102 and the transparent conductive layer 105. Generally, the first electrode and the second electrode are selected from metal electrodes.

In this embodiment, the second semiconductor layer is disposed as a sidewall inclined structure, and then a transparent conductive layer is coated on the top surface thereof and extended to the inclined sidewall thereof, so that the transparent conductive layer and the inclined sidewall can be increased. The contact area is effectively increased relative to a conventional planar structure (vertical/non-tilted sidewall structure), which helps to reduce the operating voltage of the LED. In addition, the luminescent layer in the epitaxial stack radiates a metal extending electrode (transparent conductive layer) in which the light illuminates the sidewall inclined structure, and reflects the light to the sidewall according to the incident-reflection principle, thereby increasing the light output rate of the LED component. It is no longer as the conventional structure of the luminescent layer radiates light and is reflected back to the luminescent layer to absorb the phenomenon, thereby improving the light extraction efficiency.

The LED structure shown in Figures 1 and 2 is a horizontal structure, which is only a preferred embodiment of the present invention, and is equally applicable to vertical structure LEDs.

Example 2

Referring to FIG. 3 and FIG. 4, the LED chip of the present embodiment includes: an epitaxial growth substrate 201, a first semiconductor layer 202, a light-emitting layer 203, a second semiconductor layer 204 having a convex structure 208, and a transparent conductive layer 205. The first electrode 206 and the second electrode 207.

Specifically, the epitaxial growth substrate 201 is preferably an AlN non-conductive substrate, and a buffer layer (not shown) is formed over the substrate 201.

The light emitting epitaxial layer is formed on the buffer layer, and includes a first semiconductor layer 202, a light emitting layer 203, and a second semiconductor layer 204 in order from bottom to top, wherein the first semiconductor layer 202 is an N-type semiconductor coating layer having a The first region and the second region; the light-emitting layer 203 is a multiple quantum well structure; and the second semiconductor layer 204 is a P-type semiconductor cladding layer having a raised structure 208.

In this embodiment, the first semiconductor 202 is formed on the first region; the second semiconductor layer 204 is formed on the The light layer 203 has a plurality of convex structures 208 having a top surface, a bottom surface and at least one inclined side edge, wherein the inclined side wall forms an acute angle θ with the inner side of the bottom surface, and the acute angle θ can be selected. Between 15 and 75, a preferred angle of 40 is preferred in this embodiment.

The transparent conductive layer 205 is formed on a top surface of the portion of the protruding structure 208 and extends to the inclined side thereof, so that the ohmic contact area can be effectively increased and the operating voltage of the light emitting diode can be reduced.

In this embodiment, the transparent conductive layer 205 may be a metal electrode such as AuZn, AuBe, CrAu or the like which can form an ohmic contact with the semiconductor, or a non-metal electrode such as ITO, IZO or GZO, and the transparent conductive layer 205 is preferably an ITO material. As an extension electrode of the subsequent metal electrode.

A first electrode (metal electrode) 206 and a second electrode (metal electrode) 207 are formed on the second region of the first semiconductor layer 202 and on the transparent conductive layer 205, respectively.

In this embodiment, the second semiconductor layer is disposed as a convex structure having inclined sides, and then a transparent conductive layer is coated on the top surface thereof and extended to the inclined side edges thereof, thereby increasing the transparent conductive layer and The contact area of the slanted side edges is effectively increased with respect to a conventional planar structure (non-convex structure), which contributes to lowering the operating voltage of the light emitting diode. In addition, the illuminating layer in the epitaxial stack radiates light from the obliquely extending electrode of the inclined structure of the sidewall, and reflects the light to the side wall of the opposite side according to the incident-reflection principle, thus increasing the light output rate of the LED component without Further, if the radiant light of the conventional structure is reflected on the metal electrode and reflected back to the luminescent layer to generate an absorption phenomenon, the light extraction efficiency is improved.

Example 3

Referring to FIG. 5 and FIG. 6, different from the second embodiment, the inclined sides of the protruding structure 308 of the embodiment are parallel to each other, and the light radiated from the light-emitting layer is reflected upward through the mutually inclined inclined sides ( Outside), this helps to further improve the light extraction efficiency.

Example 4

Referring to FIG. 7 to FIG. 12, the embodiment provides a method for fabricating an LED chip. The specific process steps are as follows:

Referring to FIG. 7 , an epitaxial growth substrate 401 , preferably a sapphire substrate is provided. A light-emitting epitaxial laminate is formed on the substrate 401 by epitaxy, and includes at least a first semiconductor layer 402 , a light-emitting layer 403 and a The second semiconductor layer 404, wherein the first semiconductor layer has a first region and a second region.

Referring to FIG. 8, a surface of the second semiconductor layer 404 is etched down from the surface of the second semiconductor 404 to the inside of the first semiconductor layer 402 by a dry etching process, so that a portion of the first semiconductor layer 402 is exposed, that is, the second region is exposed, and the light is emitted. The layer is located on the first region of the first semiconductor layer, and may be combined with a chemical etching gas such as BCl ₃ , CF ₄ or the like in the dry etching process.

Referring to FIG. 9, a plurality of bumps 408 are formed on the second semiconductor layer by a dry etching process. Through the boring cutting process, the protrusion has a top surface, a bottom surface and at least one inclined side edge, and a region sandwiched between the protrusions is defined as a channel, that is, the inclined side edge forms an acute angle with the inner side of the bottom surface. θ, the acute angle θ is optionally between 15 and 75°, and is preferably 60° in this embodiment.

Referring to FIG. 10, on a portion of the protrusions 408 of the second semiconductor layer, an IZO transparent conductive layer 405 is deposited by a CVD process and extended to the inclined sides of the protrusions 408, and further, in the trenches. A portion of the transparent conductive layer is also deposited in the track.

Referring to FIG. 11, a first electrode (metal electrode) 406 and a second electrode (metal electrode) 407 are formed on the second region of the first semiconductor layer 402 and the IZO transparent conductive layer 405, respectively, from FIG. The light path diagram shows that the light emitted by the light-emitting layer passes through the convex inclined side wall, and after one or more total reflections, it is emitted from the front side or the side surface of the chip.

Referring to FIG. 12, it should be noted that, besides depositing a whole transparent conductive layer on the inclined side of the protrusion 408, a transparent conductive layer may be deposited on the top surface and the channel of the protrusion to form a strip shape. Or a strip shape, which can be perpendicular to the channel in the horizontal direction, so that the transparent conductive layer can serve as a good current spreading strip, and can be reduced as much as possible while ensuring an effective increase in the ohmic contact area. The shading area reduces the operating voltage and improves the light extraction efficiency.

The light-emitting diode chips in the above embodiments can be applied to various display systems, illumination systems, automobile taillights and the like.

Claims (10)

LED chips, including: a first semiconductor layer having a first region and a second region; a light emitting layer formed on the first region of the first semiconductor layer; a second semiconductor layer is formed on the light emitting layer, and has a top surface, a bottom surface and an inclined sidewall, the inclined sidewall forming an acute angle with the bottom surface of the inner side of the second semiconductor layer; a transparent conductive layer formed on a top surface of the portion of the second semiconductor layer and extending to the inclined sidewall of the second semiconductor layer; A first electrode and a second electrode are respectively formed on the second region of the first semiconductor layer and on the transparent conductive layer. LED chips, including: a first semiconductor layer; a light emitting layer formed on the first semiconductor layer; a second semiconductor layer is formed on the light-emitting layer, and has a plurality of protrusions, and the protrusion has a top surface, a bottom surface and at least one inclined side edge, and the inclined side edge forms a side with the inner side of the bottom surface Sharp angle a transparent conductive layer formed on a top surface of a portion of the protrusion and extending to an inclined side of the protrusion; An electrode is formed on the transparent conductive layer. The light emitting diode chip according to claim 2, wherein a region sandwiched between the adjacent protrusions is defined as a channel, and a transparent conductive layer is also formed on the channel. The light emitting diode chip according to claim 2, wherein the inclined sides of the protrusions are parallel to each other. The light emitting diode chip according to claim 1 or 2, wherein the acute angle is between 15 and 75 degrees. The LED chip according to claim 1 or 2, wherein the transparent conductive layer extends to the inclined sidewall or the inclined side of the second semiconductor layer, thereby effectively increasing the ohmic contact area and reducing the operating voltage of the LED. The manufacturing method of the LED chip includes: Providing a substrate; Forming a light emitting epitaxial stack on the substrate, the method comprising at least a first semiconductor layer, a light emitting layer and a second semiconductor a layer, wherein the first semiconductor layer has a first region and a second region; Etching down from the surface of the second semiconductor to the first semiconductor layer by an etching process such that a portion of the first semiconductor layer is exposed, that is, the second region is exposed, and the light emitting layer is located at the first of the first semiconductor layer Regionally Forming, by the etching process or laser cutting or dicing cutting or any combination of the foregoing, the second semiconductor to form an inclined sidewall, the inclined sidewall forming an acute angle with the bottom surface of the inner side of the second semiconductor layer; Depositing a transparent conductive layer on a top surface of a portion of the second semiconductor layer and extending onto the inclined sidewall of the second semiconductor layer; respectively forming a second region on the first semiconductor layer and on the transparent conductive layer An electrode and a second electrode. The manufacturing method of the LED chip includes: Providing a substrate; Forming a light emitting epitaxial stack on the substrate, comprising at least a first semiconductor layer, a light emitting layer and a second semiconductor layer; Forming a plurality of protrusions on the second semiconductor layer by an etching process or laser cutting or dicing cutting or any combination of the foregoing, and having the protrusions have a top surface, a bottom surface, and at least one inclined side An edge, that is, the inclined side edge forms an acute angle with the inner side of the bottom surface; Forming a transparent conductive layer on at least a top surface of the partially convex portion and extending to an inclined side edge of the protrusion; An electrode is formed on the transparent conductive layer. The method of fabricating an LED chip according to claim 8, wherein a region sandwiched between the adjacent protrusions is defined as a channel, and a transparent conductive layer is further formed on the channel. The method of fabricating an LED chip according to claim 8, wherein the inclined sides of the protrusion are parallel to each other.

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