KR101259996B1 - Flip bonding type light emitting device and mehtod for fabricating the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a flip-bonded light emitting device, wherein the metal bumps connecting the electrode layers of the LED chip and the electrode pads of the submount on the p-type semiconductor layer and the n-type semiconductor layer are softly formed to have sufficient deformation margin. It is a technical subject to form.

To this end, the present invention provides a method of manufacturing a flip-bonded light emitting device having a submount and an LED chip flip-bonded to the submount, the method of manufacturing a flip-bonded light-emitting device according to the present invention, the opposite side of the transparent substrate preparing an LED chip having a p-type semiconductor layer and an n-type semiconductor layer stepped and providing first and second electrode layers on the p-type semiconductor layer and the n-type semiconductor layer, respectively, the first electrode layer and the second electrode Forming first and second metal bumps on each of the electrode layers by plating, and varying heights of the first and second metal bumps, respectively, the first and second electrode pads on the submount and the first and second bumps; Connecting between the second electrode layers with the first and second metal bumps.

Flip bonding, metal bump, LED chip, plating, light emitting device, pattern

Description

Flip bonding type light emitting device and manufacturing method thereof {FLIP BONDING TYPE LIGHT EMITTING DEVICE AND MEHTOD FOR FABRICATING THE SAME}

1 to 3 are schematic perspective views for explaining a manufacturing process of the LED chip of the flip-bonded light emitting device according to an embodiment of the present invention.

4 to 6 are schematic cross-sectional views for explaining a metal bump forming process of a flip-bonded light emitting device according to an embodiment of the present invention.

7 and 8 are cross-sectional views illustrating a process of flip-bonding an LED chip to a submount according to an embodiment of the present invention.

9 is a photograph showing a light emitting area of a flip-bonded light emitting device manufactured according to an embodiment of the present invention.

10A to 10C are photographs showing light emitting regions of flip-bonded light emitting devices manufactured according to another exemplary embodiment of the present invention.

Figure 11 is a photograph showing the light emitting area of the flip-bonded light emitting device manufactured according to the prior art.

<Code Description of Main Parts of Drawing>

100: LED chip 10: transparent substrate

20: n-type semiconductor layer 30: active layer

40: p-type semiconductor layer 52, 54: electrode layer

62, 64: metal bump 80: submount

The present invention relates to a flip-bonding light emitting device having an LED chip and a submount to which the LED chip is flip-bonded, and a method of manufacturing the same.

The flip-bonded light emitting device is manufactured by flip-bonding an LED chip having a transparent substrate to a submount so that light is emitted from the transparent substrate. The flip bonding type light emitting device uses an LED chip in which an n-type semiconductor layer, an active layer, and a p-type semiconductor layer are sequentially formed on a transparent substrate. At this time, the LED chip has a structure in which a portion of the n-type semiconductor layer is exposed from the opposite side of the transparent substrate by removing the active layer and a portion of the p-type semiconductor layer. Further, for example, Ni / Au series electrode layers are formed on each of the p-type semiconductor layer and the n-type semiconductor layer opposite to the transparent substrate. For flip bonding of the LED chip, metal bumps connecting between the electrode layers of the LED chip and the electrode pads (or electrode patterns) on the submount are formed in each of the electrode layers. As the metal bumps connect the electrode layers of the LED chip and the electrode pads of the submount, the transparent substrate of the LED chip forms an area where light generated in the active layer is emitted to the outside.

In the conventional method of manufacturing a flip-bonded light emitting device, an E-beam Evaporation method is used to form metal bumps. That is, by using a photoresist and exposure, the area where the metal bumps are to be formed in the electrode layer is predetermined, and the target metal material is evaporated using an electron beam having a high energy to deposit the vaporized metal material in the areas on the predetermined electrode layer. In this way metal bumps of high hardness are formed.

However, the conventional method of connecting between the electrode layers of the LED chip and the electrode pads of the submount using metal bumps of high hardness as described above has the following problems. First, since the metal bumps described above have very little or no deformation margin in the height direction, the gaps between them are not compensated by height deformation when connecting between different electrode layers and electrode pads. This impairs the reliable bonding connection of the LED chip to the submount, and as a result, the light emitting region defined by the active layer, the p-type bond layer, and the metal bumps on the p-type semiconductor layer when viewed from above the transparent substrate is shown in FIG. As shown in the photograph, a spectrum that lowers the luminous efficiency is generated. In addition, the conventional flip-bonded light-emitting device is to improve the luminous performance due to the lack of deformation margin of the metal bump and the process limitation that the metal bump can only be formed with a relatively small thickness (for example, 1.5㎛). There was a big limitation in changing the pattern of the p-type semiconductor layer, active layer and / or metal bumps.

Accordingly, the technical problem of the present invention is to softly form metal bumps connecting the electrode layers of the LED chip and the electrode pads of the submount on the p-type semiconductor layer side and the n-type semiconductor layer side so as to have a sufficient deformation margin, so that the flip-bonding may be performed. The deformation of the metal bumps in the height direction enables reliable flip bonding of the LED chip, thereby improving the light emitting performance of the flip bonding type light emitting device.

In addition, another technical problem of the present invention is to extend the light emitting area by using soft metal bumps having sufficient deformation margin in the height direction and simultaneously forming patterns of the active layer, the p-type semiconductor layer, and the electrode layer and the metal bumps on the p-type semiconductor layer. It is formed in a shape capable of improving the light emitting performance of the flip-bonded light emitting device.

According to an aspect of the present invention, there is provided a method of manufacturing a flip-bonded light emitting device having a submount and an LED chip flip-bonded to the submount, the manufacturing method comprising a p-type semiconductor layer and an n-type opposite the transparent substrate Preparing a LED chip having a semiconductor layer stepped and providing first and second electrode layers on the p-type semiconductor layer and the n-type semiconductor layer, respectively, by plating on each of the first electrode layer and the second electrode layer; Forming soft first and second metal bumps, varying heights of the first and second metal bumps, and between the first and second electrode pads on the submount and the first and second electrode layers. Connecting with the first and second metal bumps.

Preferably, the forming of the first and second metal bumps may include forming photoresist on the LED chip and patterning photoresist on the first and second electrode layers to define bump formation regions, respectively. And forming a seed metal homogeneous to the first and second metal bumps in each of the bump forming regions, and plating the seed metal to form the first and second metal bumps. Steps.

Preferably, the step of forming the first and second metal bumps, further comprises the step of further softening by baking heat treatment of the first and second metal bumps obtained by the plating.

Preferably, the preparing of the LED chip may include sequentially forming an n-type semiconductor layer, an active layer, and a p-type semiconductor layer on the transparent substrate, and removing the p-type semiconductor layer and some regions of the active layer. Exposing a portion of the n-type semiconductor layer, wherein the exposed region of the n-type semiconductor layer surrounds an area of the active layer and the p-type semiconductor layer that is a light emitting region.

Preferably, the first electrode layer and the first metal bump, the second electrode layer and the second metal bump are formed corresponding to the p-type semiconductor layer and the n-type semiconductor layer. In addition, the active layer and the p-type semiconductor layer preferably has a central portion and a branch extending from the center portion in the form of a branch.

According to another aspect of the invention, the p-type semiconductor layer and the n-type semiconductor layer and the sub-mount having the first and second electrode pads on one surface, and the opposite side of the transparent substrate is provided stepped and the p-type semiconductor layer and the The first and second LED chips are provided on the n-type semiconductor layer, respectively, and are formed on the first electrode layer and the second electrode layer by plating, respectively, and are softly formed. Provided is a flip-bonding light emitting device including first and second metal bumps connecting the second electrode layers to the first and second electrode pads, respectively.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example to ensure that the spirit of the invention to those skilled in the art can fully convey. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, widths, lengths, thicknesses, and the like of components may be exaggerated for convenience. Like numbers refer to like elements throughout.

Example

Hereinafter, a GaN-based light emitting device having a sapphire transparent substrate will be described as an example, but this is only one embodiment and is not intended to limit the present invention.

1 to 3 are diagrams for explaining a process of manufacturing a GaN-based mesa type LED chip according to an embodiment of the present invention.

First, as shown in FIG. 1, an n-type semiconductor layer 20, an active layer 30, and a p-type semiconductor layer 40 are sequentially formed on the sapphire transparent substrate 10. Although not shown, a buffer layer may be interposed between the sapphire transparent substrate 10 and the n-type semiconductor layer 20 to mitigate lattice mismatch. In order to form the above n-type semiconductor layer 20, active layer 30, p-type semiconductor layer 40, metal organic chemical vapor deposition (MOCVD), molecular beam growth (MBE) or hydride gas phase growth (HVPE), etc. This can be used. In addition, the above layers 20, 30, 40 may be formed continuously in the same process chamber.

In this case, the n-type semiconductor layer 20 may be formed of n-type Al _x In _y Ga _{1 -x- y} N (0≤x, y, x + y≤1), and may include an n-type cladding layer. Can be. In addition, the p-type semiconductor layer 40 may be formed of p-type Al _x In _y Ga _1-xy N (0 ≦ x, y, x + y ≦ 1), and may include a p-type cladding layer. The n-type semiconductor layer 20 may be formed by doping silicon (Si), and the p-type semiconductor layer 40 may be formed by doping zinc (Zn) or magnesium (Mg). In addition, the active layer 30 is an area where electrons and holes are recombined, and includes InGaN. The emission wavelength extracted according to the kind of material constituting the active layer 30 is determined. The active layer 30 may be a multilayer film in which a quantum well layer and a barrier layer are repeatedly formed. The quantum well layer and the barrier layer may be binary to quadruple compound semiconductor layers represented by general formula Al _x In _y Ga _{1 −x− y} N (0 ≦ x, y, x + y ≦ 1).

Next, a mesa forming process as shown in FIG. 2, that is, a portion of the active layer 30 and the p-type semiconductor layer 40 is etched in a predetermined pattern, and the n-type semiconductor layer ( A process of exposing 20 together with the p-type semiconductor layer 40 is performed. Although not shown, for the mesa forming process, steps of forming a photoresist on the p-type semiconductor layer 40 and exposing the photoresist in the predetermined pattern are preceded. At this time, the active layer 30 and the p-type semiconductor layer 40 remaining after the etching comprises a central portion 42 and a branch portion 44 extending in a branch form from the central portion 42 to have a substantially cross shape. Achieve. The pattern of the active layer 30 and the p-type semiconductor layer 40 as described above contributes to expanding the light emitting area of the flip-bonded light emitting device as described in detail below.

Next, the first and second electrode layers 52 and 54 in the form of metal pads are formed on the exposed regions of the p-type semiconductor layer 40 and the n-type semiconductor layer 20, as shown in FIG. 3. The process is carried out. According to an embodiment of the present invention, the first and second electrode layers 52 and 54 are formed of reflective electrode layers of Ni / Au. At this time, the first electrode layer 52 is formed in a substantially cross shape corresponding to the shape of the protruding portion of the p-type semiconductor layer 40, the second electrode layer 54 is in the exposed shape of the n-type semiconductor layer 20 Correspondingly formed to surround the entirety of the p-type semiconductor layer 40. The LED chip 100 thus formed is well illustrated in FIG. 3. In this specification, the term 'LED chip' is broadly defined as meaning flip-bonding to the submount 80 described below.

4 to 6 illustrate first and second metal bumps 62 and 64 (shown in FIG. 6) on the first electrode layer 52 and the second electrode layer 54 of the LED chip 100, respectively. It is sectional drawing for demonstrating a process.

First, as shown in FIG. 4, all regions of the LED chip 100 except for the first electrode layer 52 and the second electrode layer 54, or the first electrode layer 52 and the second electrode layer 54 except for the first electrode layer 52 and the second electrode layer 54. The photoresist 2 is formed in the conductive region of the LED chip 100 and the metal bump forming regions 62a and 64a are previously defined on the first and second electrode layers 52 and 54. In this case, the metal bump forming regions 62a and 64a are respectively formed on the first and second electrode layers 52 and 54 by exposing the photoresist 2 in a desired pattern. Each of the metal bump forming regions 62a and 64a may have a cross shape and a shape surrounding the cross shape, substantially corresponding to the shapes of the first and second electrode layers 52 and 54.

Next, as shown in FIG. 5, a process of forming Au as seed metals 62b and 64b in the metal bump formation regions 62a and 64a on the first and second electrode layers 52 and 54 (see FIG. 4) is performed. Is performed. In the embodiment of the present invention, the seed metal is deposited on the electrode layers 52 and 54 of the metal bump forming regions 62a and 64a by sputtering under vacuum conditions, but the seed metal 62b, It is also possible to form 64b).

A plating process is then performed to form metal bumps 62 and 64 over the seed metals 62b and 64b. The plating process is performed by electrolysis by inserting the LED chip 100 having the seed metals 62a and 62b into a plating solution. In this embodiment, the plating process is carried out under a current condition of 20 mA using a plating solution of model name "Micro FAB Au 310" purchased from "eeja" in Japan. At this time, in order to form the metal bumps 62 and 64 having a sufficient height, a photoresist having a predetermined height is further formed around the bump formation regions 62a and 64a after the above-described seed metal formation and before plating plating ( 5).

When the photoresist is removed after the plating process is completed, the first and second metal bumps 62 and 64 as shown in FIG. 6 are formed by the above plating process. Since the first and second metal bumps 62 and 64 are formed by plating, they have softer characteristics than the metal bumps according to the prior art formed by electron beam deposition. Therefore, the first and second metal bumps 62 and 64 have a larger deformation margin in the height direction than the metal bumps used in the conventional flip-bonded light emitting devices, and thus, flip bonding of the LED chip 100 described below. The width at which the height is adjusted is relatively large. In this case, it is preferable to further perform a baking heat treatment to further soften the first and second metal bumps 62 and 64. In this embodiment, the first and second metal bumps are maintained at a temperature of approximately 200 ° C. for 1 hour. Heat treatment is performed on (62, 64).

7 and 8 illustrate a process of flip-bonding the LED chip 100 to the submount 80 using the first and second metal bumps 62 and 64. 7 and 8, the submount 80 includes a p-type semiconductor layer 40 of the LED chip 100, a first electrode corresponding to the electrode layer 52, and the metal bumps 62 thereon. A pad 82 and a second electrode pad 84 corresponding to the n-type semiconductor layer 20 of the LED chip 100, the electrode layer 54 thereof, and the metal pump 64 are provided. The second electrode pad 84 is formed to have a height greater than that of the first electrode pad 82, so that the second metal bumps 62 have a stepped structure between the P-type semiconductor layer 40 and the N-type semiconductor layer 20. Do not significantly increase the height of the.

In the process of placing the first and second metal bumps 62 and 64 on the first and second electrode pads 82 and 84 and flip-bonding the LED chip 100 to the submount 80, A force F for pressing the LED chip 100 against the submount 80 is provided, by which the first and / or second metal bumps 62, 64 contract within the deformation margin they have and As a result, the LED chip 100 is reliably flip-bonded while being horizontal with respect to the submount 80. In addition, since the heights of the first and second metal bumps 62 and 64 can be formed without a significant economic cost up to approximately 5 μm, the LED chip 100 and the submount 80 may have sufficient deformation margin and height. It enables reliable flip bonding.

Reliable flip bonding and electrical contact between electrodes using the metal bumps 62 and 64 made of plating are realized, and this eliminates the spectrum that occurs in the light emitting region of the conventional flip-bonded light emitting device and inhibits the light emitting performance. 9 is a photograph of the flip-bonded light emitting device formed according to the embodiment of the present invention seen from above the transparent substrate 10. Referring to FIG. 9, the cross of the active layer 30 and the p-type semiconductor layer 40 is shown. It can be seen that the emission region corresponding to the shape is formed without a spectrum.

On the other hand, according to the shape and area of the active layer and the p-type semiconductor layer 40, and further, the first electrode layer 52 and the first metal bump 64 formed thereon, light emission of various shapes and areas corresponding thereto. Regions can be formed.

10A, 10B, and 10C are photographic views of light emitting devices according to other exemplary embodiments of the present disclosure, which vary light emitting regions according to shapes and areas of p-type semiconductor layers and the like. 10A to 10C, it can be seen that light emitting devices having various shapes including a central portion and branch portions extending from the center portion in a branch form are formed in the light emitting device.

While the invention has been described above with reference to specific embodiments, various modifications, changes or modifications may be made in the art within the spirit of the invention and the appended claims, and thus, the foregoing description and drawings It should be construed as illustrating the present invention, not limiting the technical spirit of the present invention.

According to an embodiment of the present invention, since the metal bumps connecting the electrode layer of the LED chip and the electrode pad of the submount on the p-type semiconductor layer side and the n-type semiconductor layer side are formed soft so as to have sufficient deformation margin, during flip bonding In addition, through the deformation in the height direction of the metal bumps, it is possible to flip the bonding of the reliable LED chip, thereby improving the light emitting performance of the flip-bonding light emitting device. In addition, soft metal bumps having sufficient deformation margin in the height direction are used, and patterns of the active layer, the p-type semiconductor layer, and the electrode layers and metal bumps on the p-type semiconductor layer can extend the light emitting area, and the branch shape therefrom. The light emitting performance of the flip-bonded light emitting device may be further improved by being formed in a shape including branching portions extending to each other.

Claims (11)

A method of manufacturing a flip-bonded light emitting device having a submount and an LED chip flip bonded to the submount, Preparing an LED chip having a p-type semiconductor layer and an n-type semiconductor layer stepped on opposite sides of the transparent substrate, and first and second electrode layers disposed on the p-type semiconductor layer and the n-type semiconductor layer, respectively; Forming first and second metal bumps by plating on each of the first electrode layer and the second electrode layer; Connecting the first and second electrode pads on the submount and the first and second electrode layers with the first and second metal bumps while varying the heights of the first and second metal bumps. Flip bonding type light emitting device manufacturing method characterized in that. The method of claim 1, wherein the forming of the first and second metal bumps, Forming a photoresist on the LED chip and patterning the photoresist on the first and second electrode layers to define bump formation regions, respectively; Forming a seed metal homogeneous with the first and second metal bumps in each of the bump forming regions; Plating the seed metal to form the first and second metal bumps; Flip bonding type light emitting device manufacturing method comprising a. The method of claim 2, wherein the forming of the first and second metal bumps, the flip-bonding light emitting device further comprises the step of baking heat treatment of the first and second metal bumps obtained by performing the plating Manufacturing method. The method of claim 1, wherein preparing the LED chip, Sequentially forming an n-type semiconductor layer, an active layer, and a p-type semiconductor layer on the transparent substrate; Partial regions of the p-type semiconductor layer and the active layer are removed to expose a portion of the n-type semiconductor layer, and an exposed region of the n-type semiconductor layer surrounds the regions of the active layer and the p-type semiconductor layer which become light emitting regions. Steps to do this, Flip bonding type light emitting device manufacturing method comprising a. The flip bonding of claim 4, wherein the first electrode layer and the first metal bump, the second electrode layer and the second metal bump are formed to correspond to the p-type semiconductor layer and the n-type semiconductor layer. Method of manufacturing a light emitting device. The method of claim 4, wherein the active layer and the p-type semiconductor layer have a central portion and a branch portion extending from the central portion in a branch form. delete A submount having first and second electrode pads disposed on one surface thereof; An LED chip having a p-type semiconductor layer and an n-type semiconductor layer provided on the opposite side of the transparent substrate, and first and second electrode layers disposed on the p-type semiconductor layer and the n-type semiconductor layer, respectively; And first and second metal bumps formed on the first electrode layer and the second electrode layer, respectively, connecting the first and second electrode layers to the first and second electrode pads. The LED chip includes an n-type semiconductor layer, an active layer, and a p-type semiconductor layer sequentially formed on a transparent substrate, and the n-type semiconductor layer has an exposed area exposed by removing some regions of the p-type semiconductor layer and the active layer. And an exposed region of the n-type semiconductor layer surrounds regions of the active layer and the p-type semiconductor layer. A submount having first and second electrode pads disposed on one surface thereof; An LED chip having a p-type semiconductor layer and an n-type semiconductor layer provided on the opposite side of the transparent substrate, and first and second electrode layers disposed on the p-type semiconductor layer and the n-type semiconductor layer, respectively; And first and second metal bumps formed on the first electrode layer and the second electrode layer, respectively, connecting the first and second electrode layers to the first and second electrode pads. And the first electrode layer and the first metal bump, the second electrode layer and the second metal bump are formed corresponding to the p-type semiconductor layer and the n-type semiconductor layer. The flip-bonded light emitting device of claim 8, wherein the active layer and the p-type semiconductor layer have a central portion and a branch portion extending from the central portion in a branch form. The flip bond type according to claim 8 or 9, wherein the first metal bumps are formed on the first electrode layer and by plating, and the second metal bumps are formed on the second electrode layer by plating. Light emitting element.

Images