CN203218311U - A power LED chip with N-type transparent electrode structure - Google Patents

Abstract

The utility model belongs to the technical field of manufacturing of semiconductor optoelectronic devices, and specifically relates to a power type LED chip of an N type transparent electrode structure. The power type LED chip comprises a substrate, a buffer layer, an intrinsic layer arranged on the buffer layer, an N type layer arranged on the intrinsic layer, a light emitting layer arranged on the N type layer, a P type layer arranged on the light emitting layer, a current barrier layer arranged on the P type layer, a transparent conductive layer arranged on the P type layer and the current barrier layer, a P electrode, an N type transparent electrode formed on the N type boss surface, and an N type welding-point electrode.. The N type transparent electrode effectively improves the situation of the traditional power type chip that the light is blocked and absorbed by large-area N electrode metal, and increases the light brightness of the chip. At the same time, the technology production is simple, expensive metal electrodes are replaced by the transparent electrodes, and the production cost is greatly reduced.

Description

A power LED chip with N-type transparent electrode structure

technical field

The utility model belongs to the technical field of manufacturing semiconductor optoelectronic devices, and in particular relates to a power LED chip with an N-type transparent electrode structure. the

Background technique

LED is an optoelectronic device that converts electrical energy into light energy. It has the advantages of small size, long life, no pollution, vibration resistance, and high photoelectric conversion efficiency. At present, it has been widely used in full-color display, landscape lighting, traffic lights, backlight and other fields. the

 。如果在理想的情况下只考虑四个侧面的出光，则其光提取效率可以达到18.2%，在理想的情况下从侧面出射的光是很可观的。然而在实际的功率型LED芯片中，由于电极结构复杂，N型电极环绕在芯片外围， 即使从侧面的光能很好地导出，这些出射的光线也被环顾在芯片外围的N型电极阻挡，而现如今大多说N电极都是利用吸收系数很高的金属材料制成的，因此导致芯片侧面出射的光线被不透明的N电极吸收，对于功率型LED芯片来说，大大降低了芯片的发光亮度。   For current power LED chips, sapphire is generally used as the substrate. Since sapphire is an insulator, when making electrodes, the P and N electrodes should be located on the same side of the epitaxial layer. Therefore, for power LED chips with sapphire substrates, the design of the electrode structure is very important, which is related to whether the current can spread evenly. . Generally speaking, three aspects need to be paid attention to when optimizing the electrode structure: 1) The method of using the N electrode to surround the P electrode can allow the current to enter the N electrode from the P electrode in the largest possible area, increasing the effective luminous length; 2 ) The distance between the N and P electrodes should be equal, so that the current can be distributed as evenly as possible; 3) The N electrodes are distributed on the outside, which is the same reason as 1). For gallium nitride-based LEDs, since the refractive index of the gallium nitride material is 2.4, corresponding to a total reflection angle of 24.62°, only light within the light cone can emerge from the surface of the chip. Ideally, according to calculations, there are six outgoing light cones for the light-emitting points in the light-emitting layer, so the total light extraction efficiency of GaN-based LEDs

. If only the light output from the four sides is considered under ideal conditions, the light extraction efficiency can reach 18.2%, and the light output from the sides is very considerable under ideal conditions. However, in the actual power LED chip, due to the complex electrode structure, the N-type electrode surrounds the periphery of the chip. Even if the light from the side can be well guided out, the outgoing light is blocked by the N-type electrode that looks around the periphery of the chip. Nowadays, it is mostly said that the N electrodes are made of metal materials with a high absorption coefficient, so the light emitted from the side of the chip is absorbed by the opaque N electrodes. For power LED chips, the luminance of the chip is greatly reduced. .

Utility model content

In view of the fact that the N-type electrode in the existing power LED chip is made of an opaque electrode with a high absorption coefficient, which causes the light emitted from the side to be blocked and absorbed, the purpose of this utility model is to propose an N-type transparent electrode. Structure to change the absorption and blocking of light by traditional N-type electrodes, thereby improving the brightness of the chip. the

In order to achieve the above object, the technical solution provided by the utility model is:

A power LED chip with an N-type transparent electrode structure, which sequentially includes a substrate, a buffer layer, an intrinsic layer, an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer from bottom to top, and the upper end of the P-type semiconductor layer is also provided with The transparent conductive layer and the current blocking layer, both the transparent conductive layer and the current blocking layer are in contact with the P-type semiconductor layer, and the sides of the current blocking layer except the upper and lower end faces are surrounded by the transparent conductive layer, and the upper end face of the current blocking layer is partly covered by a transparent conductive layer. The upper end surface of the current blocking layer not covered by the transparent conductive layer is connected to the P electrode; the N-type semiconductor layer is in the shape of a boss, and an N-type transparent electrode is arranged around the side of the raised part of the boss, and the boss protrudes There is a groove in the middle of the part, the groove is covered by the N-type transparent electrode, and the light-emitting layer, the P-type semiconductor layer and the current blocking layer above the groove have corresponding grooves, and the surrounding of the N-type transparent electrode is in the middle of the boss. The intersection of the slots is provided with electrodes at N-type solder joints. the

Further, the N-type transparent electrode is distributed on the periphery of the chip and the groove in the middle of the boss part, the groove is located on the N-type semiconductor layer, and the lower end surface of the electrode 10b at the N-type electrode pad is in contact with the N-type semiconductor layer, As shown in Figure 1b, there is no transparent electrode directly below, but the edge of the electrode 10b at the solder joint of the N-type electrode touches the transparent electrode, and the metal electrode alloy is deposited at the solder joint of the N-electrode, and the N-type semiconductor layer directly below the solder joint of the N-electrode Form a very good ohmic contact, and form a good contact with the transparent electrode at the edge. the

Further, the width of the N-type transparent electrode is 5um~20um. the

Further, the width of the N-type transparent electrode 10a is 12um. the

Further, the horizontal distance between the edge of the N-type transparent electrode and the edge of the P-type semiconductor layer is 2um-10um. the

Further, the horizontal distance between the edge of the N-type transparent electrode and the edge of the P-type semiconductor layer is 5um.

Further, the thickness of the N-type transparent electrode is 1500 angstroms to 5000 angstroms. the

Further, the thickness of the N-type transparent electrode is 3100 angstroms. the

Further, the N-type transparent electrode uses the same material as the transparent conductive layer, and the N-type transparent electrode can be produced during the process of making the transparent conductive layer without increasing the process. the

Preferably, there is no transparent electrode directly below the N-electrode pad, and only the edge touches the N-type transparent electrode, which increases the ohmic contact between the N-electrode pad and the N-type semiconductor layer. the

Preferably, the N-type transparent electrode structure replaces the traditional metal electrode, which reduces the production cost. the

The N-type transparent electrode and the transparent conductive layer of the utility model use the same material, and the N-type transparent electrode can be produced while evaporating the transparent conductive layer, without adding additional process flow. N-type transparent electrodes replace expensive metal electrodes, reducing production costs. The N-type transparent electrode structure can avoid the traditional N-type metal electrode from blocking and absorbing light, thereby improving the luminance of the chip. the

Preferably, there is no transparent electrode directly below the N-electrode pad, and only the edge touches the N-type transparent electrode, which increases the ohmic contact between the N-electrode pad and the N-type semiconductor layer. N-type transparent electrodes replace traditional metal electrodes, reducing production costs. the

Compared with the existing structure, the beneficial effect of the utility model is: the N-type transparent electrode will not block and absorb the light derived from the side, thereby effectively improving the luminous brightness of the chip, and the N-type transparent electrode structure adopts the same The same material as the transparent conductive layer will not increase the process. There is no transparent electrode structure directly below the N-electrode solder joint, only the edge is in contact with the N-type transparent electrode, which increases the contact characteristics of the N-electrode solder joint with the N-type semiconductor layer and the edge transparent electrode, and replaces it with an N-type transparent electrode Expensive metal electrodes reduce production costs. the

Description of drawings

Fig. 1a is a top view of a power LED chip with an N-type transparent electrode structure of the present invention. the

FIG. 1 b is a partial enlarged view (A-A sectional view) of the electrode 10 b at the N-type solder joint in FIG. 1 . the

Fig. 2 is a sectional view (B-B sectional view) of a left view of a power LED chip with an N-type transparent electrode structure. the

Fig. 3 is a cross-sectional view of the LED epitaxial wafer structure. the

FIG. 4 is a cross-sectional view of an N-type mesa structure formed by etching on the basis of FIG. 3 . the

FIG. 5 is a cross-sectional view after forming a current blocking layer structure on the basis of FIG. 4 . the

FIG. 6 is a cross-sectional view after forming a transparent conductive layer and an N-type transparent electrode structure on the basis of FIG. 5 . the

Fig. 7 is a schematic structural diagram of a power LED chip with an N-type transparent electrode structure. the

In the figure: 1-substrate, 2-buffer layer, 3-intrinsic layer, 4-N-type semiconductor layer, 5-light-emitting layer, 6-P-type semiconductor layer, 7-current blocking layer, 8-transparent conductive layer, 9-P electrode, 10a-N type transparent electrode, 10b-N type solder joint electrode. the

Detailed ways

The implementation of the utility model will be further described below in conjunction with the accompanying drawings, but the implementation and protection of the utility model are not limited thereto. the

As shown in Figure 1a and Figure 2, a power LED chip with an N-type transparent electrode structure includes a substrate 1, a buffer layer 2, an intrinsic layer 3, an N-type semiconductor layer 4, a light-emitting layer 5, and a P-type semiconductor layer from bottom to top. Semiconductor layer 6, the upper end of P-type semiconductor layer 6 is also provided with transparent conductive layer 8 and current blocking layer 7, transparent conductive layer 8 and current blocking layer 7 are all in contact with P-type semiconductor layer 6, and current blocking layer 7 except upper and lower end faces The side surfaces of the current blocking layer 7 are surrounded by a transparent conductive layer 8, the upper end surface of the current blocking layer 7 is covered by the transparent conductive layer 8, and the upper end surface of the current blocking layer 7 not covered by the transparent conductive layer 8 is connected to the P electrode; the N-type semiconductor Layer 4 is in the shape of a boss, and an N-type transparent electrode 10a is provided around the side of the protruding part of the boss, and a groove is opened in the middle of the protruding part of the boss. 5. Both the P-type semiconductor layer 6 and the current blocking layer 7 are provided with corresponding grooves, and the N-type solder joint electrode 10b is provided at the intersection of the periphery of the N-type transparent electrode 10a and the groove in the middle of the boss. the

N-type transparent electrodes are distributed on the periphery of the chip and at the groove in the middle of the boss part, the groove is located above the N-type semiconductor layer, and the lower end surface of the N-type electrode pad 10b is in contact with the N-type semiconductor layer, as shown in Figure 1b, There is no transparent electrode directly below, but the edge of 10b at the N-type electrode solder joint touches the transparent electrode, and the metal electrode alloy is deposited at the N-type electrode solder joint, and the N-type electrode solder joint forms a good ohmic contact with the N-type semiconductor layer directly below Contact, and form a good contact with the transparent electrode at the edge

In the actual production process, according to production requirements, a DBR (Distributed Bragg Reflection) layer formed under the substrate 1 and a passivation layer on the chip surface are also included. After the substrate 1 is thinned to the required thickness by chemical or mechanical polishing, a DBR reflective layer is back-plated on the bottom of the substrate 1. For power LED chips with a front-mounted structure, the light emitted to the substrate 1 can be reflected Go back, thereby improving the light extraction efficiency of the chip. As for the passivation layer on the surface of the chip, on the one hand, it can prevent the short circuit of the LED during operation and protect the chip; on the other hand, by controlling the refractive index of the passivation layer, the loss of the critical angle can be reduced. In the utility model, the N-type transparent electrode can make better use of the light emitted to the side, thereby improving the luminous brightness of the chip. Referring to Fig. 1, the width 10a of the N-type transparent electrode structure is between 5um and 20um, and the preferred width is 12um; the distance between the N-type transparent electrode structure and the edge of the P-type semiconductor layer is 2um to 10um. The preferred distance is 5um. Referring to FIG. 2 , the thickness of the N-type transparent electrode structure is 1500 angstroms to 5000 angstroms, preferably 3100 angstroms. the

The utility model discloses a manufacturing process of the above-mentioned structure. In the first step, the sapphire substrate 1 is placed in MOCVD (metal organic compound vapor phase epitaxy), and the alkyl compound vapor of group III metal elements and the non-metallic hydride gas are introduced, and the pyrolysis reaction is performed at high temperature to generate III- Group V compounds. A buffer layer 2, an intrinsic layer 3, an N-type semiconductor layer 4, a light-emitting layer 5, and a P-type semiconductor layer 6 are sequentially grown on the substrate 1 to grow an LED epitaxial wafer structure, as shown in FIG. 3 . The second step is to form the mesa structure for making the N-type transparent electrode 10a by etching, and use the ICP (inductively coupled plasma) etching technology to etch the N-type mesa (convex shape) through pattern exposure semiconductor planar technology, The thickness of the etched edge part is smaller than the thickness of the unetched central part, and then the mask layer is etched away by chemical etching to obtain a convex shape of the N-type semiconductor layer, as shown in FIG. 4 . The third step is to form a current blocking layer structure on the top of the P-type layer. The material used for the current blocking layer can be SiO ₂ , SiON, _Six N _y , etc. After cleaning and drying, the current blocking layer can be passed through PECVD ( Plasma-enhanced chemical vapor deposition) process, and then through the photolithography process, and then by chemical etching, the part that is not used as the current blocking layer is etched away, and then the mask layer is removed, and after cleaning and drying, the structure of the current blocking layer is obtained. See Figure 5 shows. The fourth step is to evaporate ITO (indium tin oxide) thin film on the surface of P-type semiconductor layer and N-type semiconductor layer by using evaporation table or sputtering coating method, and then through photolithography, corrosion, cleaning, and alloy process to obtain transparent conductive The layer structure 8 and the N-type transparent electrode structure 10a are shown in FIG. 6 . The fifth step is to form a P electrode 9 with a metal electrode structure on the transparent conductive layer 8 and directly above the corresponding current blocking layer 7 through processes such as evaporation, yellow light, stripping, and cleaning. The electrode 10b is formed at the edge of the electrode at the N-type solder joint, and the material used as the electrode can be Cr/Pt/Au alloy, Ni/Au alloy, Ti/Al/Ti/Au alloy or any combination of the foregoing, so that A power LED chip with an N-type transparent electrode structure was produced, as shown in FIG. 7 .

The above description is only for convenience to illustrate the utility model patent. Without departing from the spirit category of the utility model patent, the simple disguise and modification made by those skilled in the art still belong to the protection scope of the utility model. the

Claims (5)

1. the power-type LED chip of a N-type transparent electrode structure, it is characterized in that comprising successively from bottom to up substrate, resilient coating, intrinsic layer, n type semiconductor layer, luminescent layer and p type semiconductor layer, the p type semiconductor layer upper end also is provided with transparency conducting layer and current barrier layer, transparency conducting layer all contacts with p type semiconductor layer with current barrier layer, and the side of current barrier layer except the upper and lower end face all surrounded by transparency conducting layer, the upper surface part of current barrier layer is covered by transparency conducting layer, and current barrier layer is not connected with the P electrode by the upper surface part that transparency conducting layer covers; Described n type semiconductor layer is the boss shape, the part side periphery that boss protrudes is provided with the N-type transparency electrode, the middle fluting of part that boss is outstanding, this groove is covered by the N-type transparency electrode, and the luminescent layer of the top of this groove, p type semiconductor layer and current blocking all have corresponding groove layer by layer, and the infall with the middle fluting of boss around the N-type transparency electrode is provided with N-type solder joint place electrode.

2. the power-type LED chip of a kind of N-type transparent electrode structure according to claim 1 is characterized in that: the N-type transparency electrode is distributed in the periphery of chip and the fluting place in the middle of the projection section, and this groove is positioned at above the n type semiconductor layer; The lower surface of N-type electrode pads place electrode contacts with n type semiconductor layer, under do not have transparency electrode, just the EDGE CONTACT of N-type electrode pads place electrode is to transparency electrode, N electrode pads place deposit metal electrodes alloy, N-type electrode pads place both and under n type semiconductor layer form good ohmic contact, form excellent contact with the transparency electrode of edge again.

3. the power-type LED chip of a kind of N-type transparent electrode structure according to claim 1, it is characterized in that: the width of described N-type transparency electrode is 5um ~ 20um.

4. the power-type LED chip of a kind of N-type transparent electrode structure according to claim 1, it is characterized in that: the edge of described N-type transparency electrode is 2um ~ 10um far from the horizontal range at p type semiconductor layer edge.

5. the power-type LED chip of a kind of N-type transparent electrode structure according to claim 1, it is characterized in that: the thickness of described N-type transparency electrode is 1500 dusts ~ 5000 dusts.

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