KR102097865B1 - light emitting diodes - Google Patents

Abstract

A method of manufacturing a light emitting device according to an embodiment of the present invention, a GaN buffer layer, a first n-type GaN layer, a first multi-quantum well layer, a first p-type AlGaN layer, and a first p-type GaN sequentially on a growth substrate Forming a layer; Locally removing the p-type GaN layer, the p-type AlGaN layer, and the first multi-quantum well layer; And forming a second n-type GaN layer, a second multi-quantum well layer, a second p-type AlGaN layer, and a second p-type GaN layer at a position where the first multi-quantum well layer is locally removed; It includes.

Description

Light emitting diodes

The present invention relates to a light emitting device, and more particularly, to a light emitting device capable of realizing color.

2. Description of the Related Art Semiconductor light emitting devices are widely used as light sources for lighting devices as well as display devices for various electronic products such as TVs, mobile phones, PCs, and laptops.

Conventional display devices are mainly composed of a display panel and a backlight composed of a liquid crystal display (LCD). However, recently, a micro LED display technology in which a backlight is not required is being developed by using a light emitting device as one pixel. However, when the light-emitting elements mounted on the substrate are used as individual pixels, the display device has a limitation in size reduction for improving resolution and it is difficult to suppress light interference between pixels.

Korean Patent Publication No. 10-2017-010999 discloses a micro LED using an ultraviolet LED and a phosphor for each color. Color LEDs using UV LEDs and R / G / B phosphors cause a lot of energy loss by the phosphors. Therefore, a color LED using a phosphor to a minimum is required.

One technical problem to be solved of the present invention is to provide a light emitting device that implements a color by using a phosphor to a minimum.

The light emitting device according to an embodiment of the present invention provides a method of simultaneously manufacturing a light emitting device that emits green light and a light emitting device that emits blue light.

A method of manufacturing a light emitting device according to an embodiment of the present invention, a GaN buffer layer, a first n-type GaN layer, a first multi-quantum well layer, a first p-type AlGaN layer, and a first p-type GaN sequentially on a growth substrate Forming a layer; Locally removing the p-type GaN layer, the p-type AlGaN layer, and the first multi-quantum well layer; And forming a second n-type GaN layer, a second multi-quantum well layer, a second p-type AlGaN layer, and a second p-type GaN layer at a position where the first multi-quantum well layer is locally removed; It includes.

In one embodiment of the present invention, the first multiple quantum well layer includes a GaN barrier layer and an In _x Ga _y N well layer, x + y = 1, x is 0.04 to 0.14, and the second multiple The quantum well layer includes a GaN barrier layer and In _a Ga _b N well layer, a + b = 1, and a may be 0.2 to 0.22.

In one embodiment of the present invention, forming a first insulating layer on the first p-type GaN layer and the second p-type GaN layer; Patterning the first insulating layer to form contact holes exposing the first n-type GaN layer and the second n-type GaN layer, respectively; Patterning the first insulating layer to form auxiliary contact holes exposing the first p-type GaN layer and the second p-type GaN layer, respectively; Forming insulating sidewalls on sidewalls of the contact holes and the auxiliary contact hole; Forming contact plugs filling the contact holes and the auxiliary contact hole; And forming an intermediate conductive pad disposed on the contact plugs.

In one embodiment of the present invention, forming a first light emitting structure including the first multi-quantum well layer by locally etching the GaN buffer layer and the layers stacked on the GaN buffer layer; And forming a second light emitting structure including the second multi-quantum well layer by locally etching the GaN buffer layer and the layers stacked on the GaN buffer layer.

In an embodiment of the present invention, forming a third light emitting structure including the first multi-quantum well layer by locally etching the GaN buffer layer and the layers stacked on the GaN buffer layer may be further included. have. The first light emitting structure, the second light emitting structure, and the third light emitting structure may be disposed to be spaced apart from each other.

In one embodiment of the present invention, forming a protective layer to cover the first light emitting structure, the second light emitting structure, and the third light emitting structure; Forming a contact pad aligned with the intermediate conductive pad and penetrating the protective layer; Attaching a support substrate so as to face the contact pad and removing the growth substrate; And forming a red fluorescent layer on the GaN buffer layer of the exposed third light emitting structure after removing the growth substrate.

In one embodiment of the present invention, performing a mesa etch to locally expose the first n-type GaN layer and the second n-type GaN layer; An n-type ohmic electrode is formed on the first n-type GaN layer and the second n-type GaN layer exposed by the mesa etching, and a p-type ohmic is formed on the first p-type GaN layer and the second p-type GaN layer. Forming an electrode; And the first multiple quantum well layer by locally etching the exposed first n-type GaN layer and the second n-type GaN layer to expose the growth substrate, and the second multiple quantum well. And forming a second light emitting structure including a layer and a third light emitting structure including the first multi-quantum well layer. The first light emitting structure, the second light emitting structure, and the third light emitting structure may be disposed to be spaced apart from each other.

In one embodiment of the present invention, forming a protective layer to heat the first light emitting structure, the second light emitting structure, the third light emitting structure; Forming a first contact pad aligned with the n-type ohmic electrode and penetrating the protective layer and a second contact pad aligned with the p ohmic electrode and penetrating the protective layer; And attaching a support substrate facing the first contact pad and the second contact pad and removing the growth substrate.

In one embodiment of the present invention, the method may further include forming a red fluorescent layer on the GaN buffer layer of the second light emitting structure exposed by removing the growth substrate.

The light emitting devices according to the exemplary embodiment of the present invention include light emitting structures including a first light emitting structure, a second light emitting structure and a third light emitting structure spaced apart from each other; And a red fluorescent layer disposed on one surface of the third light emitting structure to receive blue light and emit red light. The first light emitting structure and the third light emitting structure emit blue light, and the second light emitting structure emits green light.

In one embodiment of the present invention, the first light emitting structure and the third light emitting structure include a first n-type GaN layer, a first multi-quantum well layer, a first p-type AlGaN layer, and a first p-type GaN layer. And the second light emitting structure includes a second n-type GaN layer, a second multi-quantum well layer, a second p-type AlGaN layer, and a second p-type GaN layer, and the first multi-quantum well layer comprises the It may have a different structure or composition from the second multiple quantum well layer.

In one embodiment of the present invention, the first light emitting structure and the second light emitting structure may further include transparent insulating layers respectively disposed on one surface.

In one embodiment of the present invention, a black partition wall disposed between the transparent insulating layers or between the transparent insulating layer and the red fluorescent layer may be further included.

In one embodiment of the present invention, it may further include a transparent film disposed on the transparent insulating layers and the red fluorescent layer.

In one embodiment of the present invention, the first light emitting structure, the second light emitting structure and the third light emitting structure may further include a support substrate disposed on the other surface.

In one embodiment of the present invention, the first light emitting structure, the second light emitting structure, and may further include intermediate electrode pads and contact pads respectively disposed on the other surfaces of the third light emitting structure.

In one embodiment of the present invention, the n-type ohmic electrode disposed on the first n-type GaN layer or the second n-type GaN layer of the first to third light emitting structures; A p-type ohmic electrode disposed on the first p-type GaN layer or the second p-type GaN layer of the first to third light emitting structures; And electrically connecting the n-type ohmic electrode and the p-type ohmic electrode and further comprising contact pads.

The light emitting device according to an embodiment of the present invention simultaneously manufactures a light emitting device that emits green light and a light emitting device that emits blue light, and the red device can implement a color by using a phosphor in a blue device.

1 is a cross-sectional view showing a light emitting device according to an embodiment of the present invention.
2A to 2M are cross-sectional views illustrating a method of manufacturing a light emitting device according to an embodiment of the present invention.
3 is a cross-sectional view illustrating a light emitting device according to another embodiment of the present invention.
4A to 4F are cross-sectional views illustrating a method of manufacturing a light emitting device according to another embodiment of the present invention.

Micro LEDs require R / G / B pixels to realize color. R / G / B pixels are difficult to grow simultaneously on a single growth substrate. Accordingly, each of the R / G / B light-emitting elements grown on different substrates is transferred to the support substrate using pick & place equipment. However, pick & place equipment is difficult to transport a micrometer-sized LED device due to low precision. Therefore, direct transfer technology is required. R / G / B phosphors are required to realize color after directly transferring UV LED elements. However, it is not easy to pattern the R / G / B fluorescent layer to a micrometer size, and the use of multiple fluorescent layers reduces energy efficiency. Therefore, it is required to reduce the R / G / B fluorescent layer in the direct transfer method.

According to an embodiment of the present invention, after forming a pair of blue LEDs and green LEDs on the same growth substrate at the same time, the light emitting device may form an R / G / B color LED pixel using a red phosphor only on one blue LED. Can be. In the method of simultaneously forming the blue LED and the green LED on the same growth substrate, after forming the thin films of the blue light emitting structure, the blue light emitting structure is locally removed, and then the green light emitting structure is formed again in the locally removed blue light emitting structure region. Subsequently, when a red phosphor is used for the blue light emitting structure, an R / G / B color LED pixel can be realized.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. However, these examples are intended to illustrate the present invention in more detail, and it will be apparent to those skilled in the art that the present invention is not limited or limited by experimental conditions, material types, and the like.

1 is a cross-sectional view showing a light emitting device according to an embodiment of the present invention.

Referring to FIG. 1, in one embodiment of the present invention, the light emitting devices 100 include a first light emitting structure 101a, a second light emitting structure 101b, and a third light emitting structure 101c disposed spaced apart from each other. Light-emitting structures 101a to 101c including; And a red fluorescent layer 178 disposed on one surface of the third light emitting structure 101c to receive blue light and emit red light. The first light emitting structure 101a and the third light emitting structure 101c emit blue light, and the second light emitting structure 101b emits green light.

The light emitting device 100 may include at least one pixel. The pixels may be arranged in a matrix form to construct a display. Each pixel may include a blue sub-pixel, a green sub-pixel, and a red sub-pixel. The blue sub-pixel may include the first light emitting structure 101a and the transparent insulating layer 176 stacked on the first light emitting structure 101a. The green sub-pixel may include the second light emitting structure 101b and the transparent insulating layer 176 stacked on the second light emitting structure 101b. The red sub-pixel may include the third light emitting structure 101c and the red fluorescent layer 178 stacked on the third light emitting structure 101c.

The first light emitting structure 101a and the third light emitting structure 101c are sequentially stacked first n-type GaN layer 112, first multi-quantum well layer 113, and first p-type AlGaN layer 114 ), And the first p-type GaN layer 115.

The second light emitting structure 101c includes a second n-type GaN layer 122 sequentially stacked, a second multi-quantum well layer 123, a second p-type AlGaN layer 124, and a second p-type GaN layer. (125). The first multiple quantum well layer 113 may have a different structure or composition from the second multiple quantum well layer 123. The first light emitting structure 101a and the third light emitting structure 101c may emit blue light, and the second light emitting structure 101b may emit green light. The first light emitting structure 101a, the second light emitting structure 101b, and the third light emitting structure 101c may be formed on the same growth substrate.

The first light emitting structure 101a and the third light emitting structure 101c are sequentially stacked GaN buffer layer 111, first n-type GaN layer 112, first multi-quantum well layer 113, and first It may include a p-type AlGaN layer 114, a first p-type GaN layer 115, and the first insulating layer 132. Among the layers constituting the first light emitting structure and the third light emitting structure, neighboring layers may be vertically aligned with each other. The first multiple quantum well layer 114 includes a GaN barrier layer and an In _x Ga _y N well layer, x + y = 1, and x may be 0.04 to 0.14. The thickness of the GaN barrier layer may be 4 nm, and the thickness of the In _x Ga _y N well layer may be 4 nm. The number of stacked GaN barrier layers and In _x Ga _y N well layers in the first multiple quantum well layer 113 may be 5. The first multi-quantum well layer 113 may emit blue light.

The second light emitting structure 101b includes a sequentially stacked GaN buffer layer 111, a first n-type GaN layer 112, a second n-type GaN layer 122, a second multi-quantum well layer 123, and a second 2 p-type AlGaN layer 124, a second p-type GaN layer 125, and may include a first insulating layer 132. Among the layers constituting the second light emitting structure 101b, neighboring layers may be vertically aligned with each other. The second multiple quantum well layer 123 includes a GaN barrier layer and an _a Ga _b N well layer, a + b = 1, and a may be 0.2 to 0.22. The thickness of the GaN barrier layer is 10 nm, and the thickness of the In _a Ga _b N well layer may be 3 nm. The number of stacked GaN barrier layers and In _x Ga _y N well layers in the second multiple quantum well layer may be 6. The second multi-quantum well layer 123 may emit green light.

In the first light emitting structure 101a, the contact plug 142 includes a first multi-quantum well layer 113, a first p-type AlGaN layer 114, a first p-type GaN layer 115, and a first insulation It may be disposed to penetrate the layer 132 and contact the first n-type GaN layer 112. In addition, the contact plug 144 may be disposed to penetrate the first insulating layer 132 and contact the first p-type GaN layer 115. The insulating side wall 137 is disposed to surround the side surfaces of the contact plugs 142 and 144.

In the second light emitting structure 101b, the contact plug 142 includes a second multi-quantum well layer 123, a second p-type AlGaN layer 124, a second p-type GaN layer 125, and a first insulation It may be disposed to penetrate the layer 132 and contact the second n-type GaN layer 122. In addition, the contact plug 144 may be disposed to penetrate the first insulating layer 132 and contact the second p-type GaN layer 125. The insulating side wall 137 is disposed to surround the side surfaces of the contact plugs 142 and 144.

The intermediate conductive pads 146 and 148 may be disposed for electrical connection at the bottom surface of the contact plugs 142 and 144.

Contact pads 151 and 152 are disposed under the intermediate conductive pads 146 and 148, and between the n-type GaN layers 112 and 122 and the p-type GaN layers 115 and 125 through the contact plugs 142 and 144 and the intermediate conductive pads 146 and 148. Can inject current.

The protective layer 150 may be disposed to expose one surface of the contact pads 151 and 152 and fill a space between the intermediate conductive pads 146 and 148 and the light emitting structures 101a to 101c. The protective layer 150 may be an insulating material.

The transparent insulating layers 176 may be respectively disposed on one surface of the first light emitting structure 101a and the second light emitting structure 101b. The transparent insulating layer 176 may be a transparent insulating material.

 The black partition wall 174 may be disposed between the transparent insulating layers 176 or between the transparent insulating layer 176 and the red fluorescent layer 178. The black partition wall 174 may operate as a black matrix separating sub-pixels from each other.

The transparent film 172 may be disposed on the transparent insulating layers 176 and the red fluorescent layer 178. The transparent film 172 may be a plastic film or a glass film. After the transparent film 172 and the black partition wall 174, the transparent insulating layer 176, and the red fluorescent layer 178 are integrally formed in a film form, they are aligned on one surface of the light emitting structures 101a to 101c. Can be combined.

The support substrate 160 may be disposed on other surfaces (or lower surfaces) of the first light emitting structure 101a, the second light emitting structure 101b, and the third light emitting structure 101c. The support substrate 160 may include connection pads electrically connected to the contact pads 151 and 152. In addition, the support substrate 160 may further include a thin film transistor or a transistor to drive each sub-pixel. The support substrate 160 may be a printed circuit board, a glass substrate, or a silicon substrate.

2A to 2N are cross-sectional views illustrating a method of manufacturing a light emitting device according to an embodiment of the present invention.

2A to 2N, a method of manufacturing a light emitting device according to an exemplary embodiment of the present invention includes a GaN buffer layer 111, a first n-type GaN layer 112, and a first, on the growth substrate 110. Forming a multiple quantum well layer 113, a first p-type AlGaN layer 114, and a first p-type GaN layer 115; Locally removing the p-type GaN layer 115, the p-type AlGaN layer 114, and the first multi-quantum well layer 113; And a second n-type GaN layer 122, a second multi-quantum well layer 123, a second p-type AlGaN layer 124, and a second multi-quantum well layer 113 where the first multi-quantum well layer 113 is locally removed. Forming a 2 p-type GaN layer 125; It includes. The first multiple quantum well layer 113 includes an alternately stacked GaN barrier layer and an In _x Ga _y N well layer, x + y = 1, and x may be 0.04 to 0.14. The second multi-quantum well layer 123 may include alternatingly stacked GaN barrier layers and In _a Ga _b N well layers, a + b = 1, and a 0.2 to 0.22.

2A, a GaN buffer layer 111, a first n-type GaN layer 112, a first multi-quantum well layer 113, and a first p-type AlGaN layer 114 on the growth substrate 110 in turn, And a first p-type GaN layer 115 is formed. The growth substrate 110 may be Si, Al2O3, SiC. Preferably, the growth substrate may be a sapphire (Al2O3) substrate. The sapphire substrate may be a double side polished substrate.

The GaN buffer layer 111 may be formed on the growth substrate 110. The GaN buffer layer 111 is a GaN layer that is not doped with impurities, and may have a thickness of 2 μm. The GaN buffer layer 111 may be grown by MOCVD.

The first n-type GaN layer 112 may be formed on the GaN buffer layer 111. The first n-type GaN layer 112 may be a GaN layer doped with n-type impurities (for example, Si). The thickness may be 3 μm level. The first n-type GaN buffer layer 112 may be grown by MOCVD.

The first multi-quantum well layer 113 may be formed on the first n-type GaN layer 112. The first multiple quantum well layer 113 includes an alternately stacked GaN barrier layer and an In _x Ga _y N well layer, x + y = 1, and x may be 0.04 to 0.14. The thickness of the GaN barrier layer may be 4 nm, and the thickness of the In _x Ga _y N well layer may be 4 nm. The number of stacks of the GaN barrier layer and the In _x Ga _y N well layer in the first multiple quantum well layer may be 5. The first multi-quantum well layer 113 may emit blue light.

 The first p-type AlGaN layer 114 may be formed on the first multiple quantum well layer 113. The first p-type AlGaN layer 114 may be an AlGaN layer doped with p-type impurities (eg Mg). The first p-type AlGaN layer 114 may have a thickness of 50 nm. The first p-type AlGaN layer 114 may be grown by MOCVD technique.

The first p-type GaN layer 115 may be formed on the first p-type AlGaN layer 114. The first p-type GaN layer 115 may be a GaN layer doped with p-type impurities (eg, Mg). The first p-type GaN layer 115 may have a thickness of 60 nm. The first p-type GaN layer 115 may be grown by MOCVD.

Referring to FIG. 2B, the p-type GaN layer 115, the p-type AlGaN layer 114, and the first multi-quantum well layer 113 are locally removed. Specifically, an epitaxial mask pattern 116 is formed on the first p-type GaN layer 115. The epitaxial mask pattern may be a silicon oxide film. The epitaxial mask pattern 116 may be a line pattern extending side by side in the first direction. The epitaxial mask pattern 116 may be formed by depositing an insulating film, such as a silicon oxide film, on the first p-type GaN layer 115, applying a photoresist, and exposing the photoresist mask. The epitaxial mask pattern 116 may be formed by etching the silicon oxide film using the photoresist mask as an etch mask. The epitaxial mask pattern 116 may have a thickness of 200 nm.

Subsequently, the first p-type GaN layer 115, the first p-type AlGaN layer 114, and the first multiply using the epitaxial mask pattern 116 or the photoresist mask as an etch mask. The quantum well layer 113 is removed locally. Subsequently, the photoresist mask is removed. Accordingly, a first region in which the first multi-quantum well layer 113 is present and a second region in which the first multi-quantum well layer 113 is removed are defined.

Referring to FIG. 2C, a second n-type GaN layer 122, a second multi-quantum well layer 123, and a second p-type AlGaN in the second region where the first multi-quantum well layer 113 is locally removed. A layer 124 and a second p-type GaN layer 125 are formed. The epitaxial mask pattern 116 is In the first region It is disposed on the first p-type GaN layer 115 to suppress the growth of the thin film.

The second n-type GaN layer 122 may be formed on the first n-type GaN layer in the second region. The second n-type GaN layer 122 may have a thickness of 0.4 μm.

The second multi-quantum well layer 123 may be formed on the second n-type GaN layer 122. The second multi-quantum well layer 123 may include alternatingly stacked GaN barrier layers and In _a Ga _b N well layers, a + b = 1, and a 0.2 to 0.22. The thickness of the GaN barrier layer is 10 nm, and the thickness of the In _a Ga _b N well layer may be 3 nm. The number of stacked GaN barrier layers and In _x Ga _y N well layers in the second multiple quantum well layer 123 may be 6. The second multi-quantum well layer 123 may emit green light.

The second p-type AlGaN layer 124 may be formed on the second multi-quantum well layer 123. The second p-type AlGaN layer 124 may have a thickness of 50 nm.

The second p-type GaN layer 125 may be formed on the second p-type AlGaN layer 124. The thickness of the second p-type GaN layer 125 may be 60 nm.

2D and 2E, after removing the epitaxial mask pattern 116, a first insulating layer (on the first p-type GaN layer 115 and the second p-type GaN layer 125) 132). The first insulating layer 132 may be a silicon oxide film or a silicon nitride film.

Referring to FIG. 2F, the first n-type GaN layer 112 and the second n-type GaN layer 122 are patterned by patterning the first insulating layer 132 and the lower layers of the first insulating layer 132. Contact holes 134 to be exposed may be formed. The contact holes 134 may be formed in the first region and the second region, respectively.

Referring to FIG. 2G, the first insulating layer 132 is patterned to form auxiliary contact holes 136 exposing the first p-type GaN layer 115 and the second p-type GaN layer 125, respectively. can do.

Referring to FIG. 2H, insulating sidewalls 137 are formed on sidewalls of the contact holes 134 and the auxiliary contact hole 136. The insulating sidewall 137 may be formed through anisotropic etching after conformally thickening an insulating layer. Accordingly, the lower surface of the contact holes 134 contacts the first n-type GaN layer 112 or the second n-type GaN layer 122. In addition, the lower surface of the auxiliary contact hole 137 contacts the first p-type GaN layer 115 or the second p-type GaN layer 125.

Referring to FIG. 2I, contact plugs 142 and 144 filling the contact holes 134 and the auxiliary contact hole 136 are formed, respectively. The contact plugs 142 and 144 may perform ohmic bonding with the semiconductor layers.

Referring to FIG. 2J, intermediate conductive pads 146 and 148 disposed on the contact plugs 142 and 144 are formed. The intermediate conductive pads 146 and 148 may electrically connect to the contact plugs 142 and 144 and the contact pads 148. The intermediate conductive pads 146 and 148 may be metal or metal alloy.

Referring to FIG. 2K, the GaN buffer layer 111 and the layers stacked on the GaN buffer layer 111 are locally etched to form a first light emitting structure 101a including the first multi-quantum well layer 113. To form. In addition, the GaN buffer layer 111 and the layers stacked on the GaN buffer layer 111 may be locally etched to form a second light emitting structure 101b including the second multi-quantum well layer 123. . In addition, the GaN buffer layer 111 and the layers stacked on the GaN buffer layer 111 may be locally etched to form a third light emitting structure 101c including the first multiple quantum well layer 113. . The first light emitting structure 101a, the second light emitting structure 101b, and the third light emitting structure 101c may be simultaneously formed. The first light emitting structure, the second light emitting structure, and the third light emitting structure may be disposed to be spaced apart from each other. The first light emitting structure, the second light emitting structure, and the third light emitting structure may be formed by etching the GaN buffer layer and the layers stacked on the GaN buffer layer using a photoresist as an etching mask. The first light emitting structure and the third light emitting structure may emit blue light, and the second light emitting structure may emit green light.

Referring to FIG. 2L, a protective layer 150 may be formed to cover the first light emitting structure 101a, the second light emitting structure 101b, and the third light emitting structure 101c. The protective layer 150 may be a silicon oxide film, a silicon nitride film, a plastic layer, or an acrylic layer, or a polymer. The upper surface of the protective layer 150 may be planarized.

2M, contact pads 151 and 152 aligned with the intermediate conductive pads 146 and 148 and penetrating the protective layer 150 may be formed. The contact pads 151 and 152 may be metal or metal alloy. One surface of the contact pads 151 and 152 may be exposed to the outside.

Referring to FIG. 2N, a support substrate 160 may be attached to the contact pads 151 and 152 and the growth substrate 110 may be removed. The growth substrate 110 may be removed through etching or a laser lift-off process. The support substrate 160 may be a temporary substrate to be removed later, a printed circuit board having electrical wiring, a substrate including a thin film transistor, or a silicon substrate including a transistor.

Referring to FIG. 1 again, after removing the growth substrate 110, a red fluorescent layer 178 may be formed on the GaN buffer layer 111 of the exposed third light emitting structure 101c. The transparent insulating layers 176 may be respectively disposed on one surface of the first light emitting structure 101a and the second light emitting structure 101b.

The black partition wall 174 may be disposed between the transparent insulating layers 176 or between the transparent insulating layer and the red fluorescent layer 178. The black partition wall may be transformed into a reflective partition wall.

 The transparent film 172 may be disposed on the transparent insulating layers 176 and the green fluorescent layer 176. The transparent film 172, the transparent insulating layer 176, and the red fluorescent layer 176 may be integrated in a film form and combined with the light emitting structures 101a to 101c.

According to an embodiment of the present invention, the first light emitting structure 101a emits blue light, the second light emitting structure 101b emits green light, and the third light emitting structure 101c emits blue light and a red fluorescent layer. It can be converted to red. Accordingly, the light emitting device of the present invention can implement a color. Compared with the use of a plurality of conventional fluorescent layers, the type of the fluorescent layer is reduced to one, thereby increasing the light efficiency.

A light emitting device according to an embodiment of the present invention may be arranged in a matrix form to provide a micro LED display. The micro LED display may be used in a display of a smart watch.

3 is a cross-sectional view illustrating a light emitting device according to another embodiment of the present invention.

Referring to FIG. 3, in one embodiment of the present invention, the light emitting devices 200 include a first light emitting structure 201a, a second light emitting structure 201b, and a third light emitting structure 201c disposed spaced apart from each other. Light-emitting structures 201a to 201c including; And a red fluorescent layer 178 disposed on one surface of the third light emitting structure 201c to receive blue light and emit red light. The first light emitting structure 201a and the third light emitting structure 201c emit blue light, and the second light emitting structure 201b emits green light.

The light emitting device 200 may include at least one pixel. The pixels may be arranged in a matrix form to construct a display. Each pixel may include a blue sub-pixel, a green sub-pixel, and a red sub-pixel. The blue sub-pixel may include the first light emitting structure 201a and the transparent insulating layer 176 stacked on the first light emitting structure 201a. The green sub-pixel may include the second light emitting structure 201b and the transparent insulating layer 176 stacked on the second light emitting structure 201b. The red sub-pixel may include the third light emitting structure 201c and the red fluorescent layer 178 stacked on the third light emitting structure 201c.

The first light emitting structure 201a and the third light emitting structure 201c are sequentially stacked first n-type GaN layer 112, first multi-quantum well layer 113, and first p-type AlGaN layer 114 ), And the first p-type GaN layer 115.

The second light emitting structure 201c includes a second n-type GaN layer 122 sequentially stacked, a second multi-quantum well layer 123, a second p-type AlGaN layer 124, and a second p-type GaN layer. (125). The first multiple quantum well layer 113 may have a different structure or composition from the second multiple quantum well layer 123. The first light emitting structure 201a and the third light emitting structure 201c may emit blue light, and the second light emitting structure 201b may emit green light. The first light emitting structure 201a, the second light emitting structure 201b, and the third light emitting structure 201c may be formed on the same growth substrate.

The first light emitting structure 201a and the third light emitting structure 201c are sequentially stacked GaN buffer layer 111, first n-type GaN layer 112, first multi-quantum well layer 113, and first The p-type AlGaN layer 114 and the first p-type GaN layer 115 may be included. Among the layers constituting the first light emitting structure and the third light emitting structure, neighboring layers may be vertically aligned with each other. The first multiple quantum well layer 114 includes a GaN barrier layer and an In _x Ga _y N well layer, x + y = 1, and x may be 0.04 to 0.14. The thickness of the GaN barrier layer may be 4 nm, and the thickness of the In _x Ga _y N well layer may be 4 nm. The number of stacked GaN barrier layers and In _x Ga _y N well layers in the first multiple quantum well layer 113 may be 5. The first multi-quantum well layer 113 may emit blue light.

The second light emitting structure 201b is a sequentially stacked GaN buffer layer 111, a first n-type GaN layer 112, a second n-type GaN layer 122, a second multi-quantum well layer 123, a second A 2 p-type AlGaN layer 124 and a second p-type GaN layer 125 may be included. Among the layers constituting the second light emitting structure 201b, neighboring layers may be vertically aligned with each other. The second multiple quantum well layer 123 includes a GaN barrier layer and an _a Ga _b N well layer, a + b = 1, and a may be 0.2 to 0.22. The thickness of the GaN barrier layer is 10 nm, and the thickness of the In _a Ga _b N well layer may be 3 nm. The number of stacked GaN barrier layers and In _x Ga _y N well layers in the second multiple quantum well layer may be 6. The second multi-quantum well layer 123 may emit green light.

The first light emitting structure 201a, the second light emitting structure 201b, and the third light emitting structure 201c may be mesa-etched. Accordingly, in the first light-emitting structure 201a and the third light-emitting structure 201c, the first multi-quantum well layer 113 and the first p-type so that a part of the first n-type GaN layer 112 is exposed. The AlGaN layer 114 and the first p-type GaN layer 115 may be removed locally. In addition, in the second light emitting structure 201b, the second multi-quantum well layer 123, the second p-type AlGaN layer 124, and the second p such that a portion of the second n-type GaN layer 122 is exposed. The type GaN layer 125 may be removed locally.

An n-type ohmic electrode 237 is disposed on the first n-type GaN layer and the second n-type GaN layer exposed by the mesa etching. In addition, a p-type ohmic electrode 238 is disposed on the first p-type GaN layer and the second p-type GaN layer.

The contact pads 251 and 252 are disposed on the n-type ohmic electrode 237 and the p-type ohmic electrode 238 to inject current between the n-type GaN layers 112 and 122 and the p-type GaN layers 115 and 125.

The protective layer 150 may be disposed to expose one surface of the contact pads 251 and 252, cover the contact pads 251 and 252, and fill the space between the light emitting structures 201a to 201c. The protective layer 150 may be an insulating material.

The transparent insulating layers 176 may be disposed on one surface of the first light emitting structure 201a and the second light emitting structure 201b, respectively. The transparent insulating layer 176 may be a transparent insulating material.

 The black partition wall 174 may be disposed between the transparent insulating layers 176 or between the transparent insulating layer 176 and the red fluorescent layer 178. The black partition wall 174 may operate as a black matrix separating sub-pixels from each other.

The transparent film 172 may be disposed on the transparent insulating layers 176 and the red fluorescent layer 178. The transparent film 172 may be a plastic film or a glass film. After the transparent film 172 and the black partition 174, the transparent insulating layer 176, and the red fluorescent layer 178 are integrally formed in a film form, they are aligned on one surface of the light emitting structures 201a to 201c. Can be combined.

The support substrate 160 may be disposed on other surfaces (or lower surfaces) of the first light emitting structure 201a, the second light emitting structure 201b, and the third light emitting structure 201c.

4A to 4F are cross-sectional views illustrating a method of manufacturing a light emitting device according to another embodiment of the present invention.

Referring again to FIGS. 2A to 2D, the GaN buffer layer 111, the first n-type GaN layer 112, the first multi-quantum well layer 113, and the first p-type AlGaN are sequentially grown on the growth substrate 110. Forming a layer 114 and a first p-type GaN layer 115; Locally removing the first p-type GaN layer 115, the first p-type AlGaN layer 114, and the first multi-quantum well layer 113; And a second n-type GaN layer 122, a second multi-quantum well layer 123, a second p-type AlGaN layer 124, and a second multi-quantum well layer 113 where the first multi-quantum well layer 113 is locally removed. Forming a 2 p-type GaN layer 125; It includes. Accordingly, the first p-type GaN layer 115 is exposed in the first region, and the second p-type GaN layer 125 is exposed in the second region.

4A and 4B, a mesa etch is performed to locally expose the first n-type GaN layer 115 and the second n-type GaN layer 125. After forming the photoresist pattern at the position where the light emitting structures 201a to 201c are formed, the thin film under the photoresist pattern is etched using an etching mask.

Referring to FIG. 4C, an n-type ohmic electrode 237 is formed on the first n-type GaN layer and the second n-type GaN layer exposed by the mesa etching, and the first p-type GaN layer and the second A p-type ohmic electrode 238 is formed on the p-type GaN layer. The n-type ohmic electrode 237 and the p-type ohmic electrode 238 may be performed by a lift-off process.

4D, the exposed first n-type GaN layer 112 and the second n-type GaN layer 122 are locally etched so that the growth substrate 110 is exposed to the first multi-quantum well layer A first light emitting structure 201a including 113, a second light emitting structure 201b including the second multiple quantum well layer 123, and a first light emitting structure including the first multiple quantum well layer 113 3 A light emitting structure 201c can be formed.

The first light emitting structure 201a, the second light emitting structure 201b, and the third light emitting structure 201c may be simultaneously formed by etching using a photoresist as an etching mask. The first light emitting structure 201a, the second light emitting structure 201b, and the third light emitting structure 201c are spaced apart from each other.

Referring to FIG. 4E, a protective layer 150 is formed to heat the first light emitting structure 201a, the second light emitting structure 201b, and the third light emitting structure 201c. The upper surface of the protective layer 150 may be planarized. The protective layer 150 may be a silicon oxide film, a silicon nitride film, a plastic layer, or an acrylic layer, or a polymer.

Referring to FIG. 4F, the first contact pad 251 aligned with the n-type ohmic electrode 237 and penetrating the protective layer 150 and the p ohmic electrode 238 are aligned with the protective layer 150. A second contact pad 252 penetrating the may be formed. The first contact pad 251 and the second contact pad 252 may be metal or a metal alloy.

Referring back to FIG. 3, a support substrate 160 facing the first contact pad 251 and the second contact pad 252 may be attached and the growth substrate 110 may be removed. The growth substrate 110 may be removed through etching or a laser lift-off process. The support substrate 110 may be a temporary substrate to be removed later, a printed circuit board having electrical wiring, a substrate including a thin film transistor, or a silicon substrate including a transistor.

The red fluorescent layer 178 may be formed on the GaN buffer layer of the second light emitting structure 201b exposed by removing the growth substrate 110.

Transparent insulating layers 176 may be respectively disposed on one surface of the first light emitting structure 201a and the second light emitting structure 201b.

The black partition wall 174 may be disposed between the transparent insulating layers 176 or between the transparent insulating layer and the red fluorescent layer. The black partition wall 174 may be transformed into a reflective partition wall.

 The transparent film 172 may be disposed on the transparent insulating layers and the green fluorescent layer. The transparent film 172, the transparent insulating layer 176, and the red fluorescent layer 178 may be integrated into a film form and combined with the light emitting structures 201a to 210c.

According to an embodiment of the present invention, the first light emitting structure 201a emits blue light, the second light emitting structure 201b emits green light, and the third light emitting structure 201c emits blue light and a red fluorescent layer. Can be converted to red.

According to a modified embodiment of the present invention, a refractive index matching layer may be disposed between the light emitting structures 201a to 201c and the transparent insulating layer or the red fluorescent layer. The refractive index matching layer may have a value between the refractive index of the transparent insulating layer and the refractive index of GaN.

In the above, the present invention has been illustrated and described with respect to specific preferred embodiments, but the present invention is not limited to these embodiments, and those skilled in the art to which the present invention pertains claim in the claims It includes all of the various types of embodiments that can be carried out without departing from the technical spirit.

100: light-emitting element
101a, 101b, 101c: Light emitting structure
178: red fluorescent layer

Claims (17)

delete delete delete delete delete delete delete delete delete In the light emitting device comprising a light emitting structure including a first light emitting structure and a second light emitting structure spaced apart from each other,
The first light emitting structure includes a GaN buffer layer, a first n-type GaN layer, a first multiple quantum well layer, a first p-type AlGaN layer, a first p-type GaN layer, and a first insulating layer,
The second light emitting structure includes the GaN buffer layer, a second n-type GaN layer, a second multiple quantum well layer, a second p-type AlGaN layer, a second p-type GaN layer, and the first insulating layer,
The first multiple quantum well layer has a different structure or composition from the second multiple quantum well layer,
A first fill hole that penetrates the first insulating layer, the first p-type GaN layer, the first p-type AlGaN layer, and the first multiple quantum well layer to expose the first n-type GaN layer; 1 contact plugs;
A second contact hole that penetrates the first insulating layer, the second p-type GaN layer, the second p-type AlGaN layer, and the second multi-quantum well layer to expose the second n-type GaN layer; 2 contact plugs;
Auxiliary contact plugs filling the auxiliary contact holes penetrating the first insulating layer and exposing the first p-type GaN layer and the second p-type GaN layer, respectively;
An insulating sidewall disposed on sidewalls of the first contact holes, the second contact holes, and the auxiliary contact holes;
An intermediate conductive pad disposed on the first contact plugs, the second contact plugs, and the auxiliary contact plugs;
The first light emitting structure is separated by locally etching the layers including the GaN buffer layer and the first multi-quantum well layer stacked on the GaN buffer layer, and includes the first multi-quantum well layer,
The second light-emitting structure is separated by locally etching the layers including the GaN buffer layer and the second multi-quantum well layer stacked on the GaN buffer layer, and includes the second multi-quantum well layer,
A third light emitting structure including the first multiple quantum well layer is further etched by locally etching the layers including the GaN buffer layer and the first multiple quantum well layer stacked on the GaN buffer layer,
In the first light emitting structure, the second light emitting structure, and the third light emitting structure, the GaN buffer layer is locally removed and spaced apart from each other,
A protective layer covering the first light emitting structure, the second light emitting structure, and the third light emitting structure;
A contact pad aligned with the intermediate conductive pad and penetrating the protective layer;
A support substrate attached to face the contact pad; And
Further comprising a red fluorescent layer disposed on the GaN buffer layer of the third light emitting structure,
Further comprising a transparent insulating layer disposed on each surface of the first light emitting structure and the second light emitting structure,
And a black partition wall disposed between the transparent insulating layers or between the transparent insulating layer and the red fluorescent layer. The method of claim 10,
The first multiple quantum well layer includes a GaN barrier layer and an In _x Ga _y N well layer,
x + y = 1, x is 0.04 to 0.14,
The second multi-quantum well layer includes a GaN barrier layer and an In _a Ga _b N well layer,
a + b = 1, and a is 0.2 to 0.22. delete delete delete delete delete delete

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