CN110739380B - Micro light-emitting element and display device - Google Patents
Micro light-emitting element and display device Download PDFInfo
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- CN110739380B CN110739380B CN201810801693.2A CN201810801693A CN110739380B CN 110739380 B CN110739380 B CN 110739380B CN 201810801693 A CN201810801693 A CN 201810801693A CN 110739380 B CN110739380 B CN 110739380B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/483—Containers
- H01L33/486—Containers adapted for surface mounting
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
- G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
- G09F9/33—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements being semiconductor devices, e.g. diodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L25/00—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
- H01L25/03—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes
- H01L25/04—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers
- H01L25/075—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00
- H01L25/0753—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00 the devices being arranged next to each other
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/62—Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
Abstract
The invention provides a micro light-emitting element which comprises an element layer, a first electrode and a second electrode. The element layer includes a body and a bump structure disposed on the body. The first electrode is electrically connected with the element layer. The second electrode is electrically connected with the element layer. The first electrode, the second electrode and the protruding structure are arranged on the same side of the body. The protruding structure is located between the first electrode and the second electrode. The connection line of the first electrode and the second electrode passes through the convex structure. The body has a surface. The protruding structure has a first height on the surface. Any one of the surfaces of the first electrode and the second electrode has a second height. The first height is H1, the second height is H2, and H1/H2 is not less than 0.8 and not more than 1.2. A display device having a plurality of micro light emitting elements is also provided.
Description
Technical Field
The present disclosure relates to light emitting devices and display devices, and particularly to a micro light emitting device and a display device.
Background
With the development of the optoelectronic technology, the conventional incandescent and fluorescent lamps have been replaced by a new generation of solid-state light source, such as light-emitting diodes (LEDs), which has advantages such as long lifetime, small size, high shock resistance, high light efficiency and low power consumption, and thus has been widely used as light sources in household lighting and various devices. In addition to the backlight module of the liquid crystal display and the household lighting fixture having widely adopted the light emitting diode as the light source, in recent years, the application field of the light emitting diode has been expanded to the fields of road lighting, large outdoor signboards, traffic signal lamps, UV curing and the like. Light emitting diodes have become one of the main projects for developing light sources with power saving and environmental protection functions.
In the LED field, a new technology called micro light emitting diode (micro light emitting diode) is developed to reduce the size of the original LED chip. Compared with the organic light emitting diode (oled) display on the market, the micro led is expected to become the mainstream of the next generation display technology due to its longer service life and lower production cost, and thus attracts the active investment of many manufacturers. However, the distance between the two electrode pads is shortened while the led is miniaturized, and during the bonding process of the led to the electronic device, the conductive solder respectively connected to the two electrode pads is likely to short-circuit due to overflow, which increases the probability of defective products.
Disclosure of Invention
The invention provides a micro light-emitting element with high transfer success rate.
The invention provides a display device with high production yield.
The embodiment of the invention provides a micro light-emitting device, which comprises a device layer, a first electrode and a second electrode. The element layer includes a body and a bump structure disposed on the body. The body has a surface. The first electrode is electrically connected with the element layer. The second electrode is electrically connected with the element layer. The first electrode, the second electrode and the protruding structure are arranged on the same side of the body. The protruding structure is located between the first electrode and the second electrode, and a connection line of the first electrode and the second electrode passes through the protruding structure. The protruding structure has a first height on the surface. Any one of the surfaces of the first electrode and the second electrode has a second height. The first height is H1, the second height is H2, and H1/H2 is not less than 0.8 and not more than 1.2.
An embodiment of the invention provides a display device, which includes a back plate, a first bonding pad, a second bonding pad, and the above-mentioned micro light-emitting device. The first bonding pads and the second bonding pads are arranged on the back plate. The first electrode of the micro light-emitting element is electrically connected to the back plate through the first bonding pad. The second electrode of the micro light-emitting element is electrically connected to the back plate through the second bonding pad. The first bonding pad and the second bonding pad are separated from each other.
In an embodiment of the invention, the maximum length of the protruding structure of the micro light emitting device is L1. The distance between the first electrode and the second electrode is S1, and L1/S1 is more than or equal to 0.8 and less than or equal to 1.
In an embodiment of the invention, the maximum length of the device layer of the above-mentioned micro light emitting device is L2, and L1/L2 is less than or equal to 0.8.
In an embodiment of the invention, the first height of the micro light emitting device is smaller than the second height, and (H2-H1)/H1 is less than or equal to 0.2.
In an embodiment of the invention, the first height of the micro light emitting device is greater than the second height, and (H1-H2)/H1 is less than or equal to 0.2.
In an embodiment of the invention, the thickness of the device layer of the above-mentioned micro light emitting device is H3, and 0.01 ≦ H1/H3 ≦ 0.95.
In an embodiment of the invention, the device layer of the micro light emitting device has two opposite side edges, and a distance between the two side edges is S2, and a shortest distance between the protrusion structure and any one of the two side edges is S3, and S3/S2 is 0.01-0.2.
In an embodiment of the invention, a ratio of an orthographic projection area of the protruding structures of the micro light emitting device on the surface of the device layer to a surface area of the surface of the device layer is less than or equal to 0.8.
In an embodiment of the invention, the body of the micro light emitting device includes a first type semiconductor layer, a light emitting layer and a second type semiconductor layer. The light emitting layer is arranged on the first type semiconductor layer. The second type semiconductor layer is arranged on the luminous layer. The convex structure is connected with the second type semiconductor layer.
In an embodiment of the invention, the device layer of the micro light emitting device includes a first type semiconductor layer, a light emitting layer and a second type semiconductor layer. The light emitting layer is arranged on the first type semiconductor layer. The second type semiconductor layer is arranged on the luminous layer. The protruding structure includes at least a portion of the second-type semiconductor layer.
In an embodiment of the invention, the protruding structure of the micro light emitting device includes a second type semiconductor layer, a light emitting layer and a portion of the first type semiconductor layer.
In an embodiment of the invention, the micro light emitting device further includes an insulating layer and a conductive layer. The insulating layer partially covers the first type semiconductor layer and the protruding structure. The conductive layer is arranged on the insulating layer and connected with the second type semiconductor layer exposed outside the insulating layer in the protruding structure. The second electrode is connected with the conductive layer, and the first electrode is connected with the first type semiconductor layer.
In an embodiment of the invention, the first electrode and the second electrode of the micro light emitting device have different electrical properties.
In an embodiment of the invention, orthographic projections of the first bonding pad and the second bonding pad of the display device on the back plate are respectively partially overlapped with an orthographic projection of the protruding structure on the back plate.
In an embodiment of the invention, orthographic projections of the first bonding pads, the second bonding pads and the protruding structures of the display device on the back plate are staggered from each other.
In an embodiment of the invention, a top surface of the protruding structure of the display device is aligned with a surface of the back plate.
In an embodiment of the invention, the back plate of the display device has a groove disposed between the corresponding first bonding pad and the second bonding pad. Part of the convex structure of the micro light-emitting element is arranged in the groove of the back plate.
Based on the above, the micro light emitting device and the display apparatus according to an embodiment of the invention have the bump structure disposed between the first electrode and the second electrode, so that in the bonding process of transferring the micro light emitting device to the display apparatus, the bonding pad connected to the first electrode and the bonding pad connected to the second electrode can be effectively prevented from being conducted due to overflow, thereby improving the production yield of the display apparatus and increasing the design margin of the micro light emitting device.
In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.
Drawings
Fig. 1 is a schematic cross-sectional view of a micro light-emitting device according to an embodiment of the invention.
Fig. 2 is a schematic top view of a micro light-emitting device according to an embodiment of the invention.
Fig. 3 is a schematic cross-sectional view of a micro light-emitting device according to another embodiment of the invention.
Fig. 4 is a schematic cross-sectional view of a micro light-emitting device according to another embodiment of the invention.
Fig. 5A to 5B are schematic cross-sectional views illustrating a bonding process of a display device according to an embodiment of the invention.
Fig. 6 is a schematic cross-sectional view of a display device according to another embodiment of the invention.
Fig. 7 is a schematic cross-sectional view of a display device according to yet another embodiment of the invention.
[ notation ] to show
10A, 10B, 10C: display device
11. 11C: back plate
11 Ca: groove
11s, 11Cs, 142 s: surface of
12: first bonding pad
13: second bonding pad
100. 100A, 100B, 100C, 100D: micro light-emitting device
110. 110A, 110B: element layer
110a, 110 b: skirt edge
111. 111A, 111B: first type semiconductor layer
112. 112A, 112B: luminescent layer
113. 113A, 113B: second type semiconductor layer
120. 120A, 120B: a first electrode
130. 130A, 130B: second electrode
140. 140A, 140B, 140C, 140D: bump structure
140 Ct: the top surface
142. 142A, 142B: body
150. 150B, 160: insulating layer
170: conductive layer
D1: a first direction
D2: second direction
D3: third direction
H1: first height
H2: second height
H3: thickness of
L1, L2: length of
S1, S2, S3: distance between each other
W1, W2, W3, W4: width of
A-A': cutting line
Detailed Description
Fig. 1 is a schematic cross-sectional view of a micro light-emitting device according to an embodiment of the invention. Fig. 2 is a schematic top view of a micro light-emitting device according to an embodiment of the invention. Fig. 1 may correspond to section line a-a' of fig. 2. Specifically, fig. 2 omits illustration of the insulating layer 150 of fig. 1.
Referring to fig. 1 and fig. 2, in the present embodiment, the micro light emitting device 100 includes a device layer 110, a first electrode 120, and a second electrode 130. The first electrode 120 is electrically connected to the device layer 110. The second electrode 130 is electrically connected to the device layer 110. The device layer 110 of the micro light emitting device 100 includes a protrusion structure 140 and a body 142, wherein the protrusion structure 140 is disposed between the first electrode 120 and the second electrode 130 and disposed on the body 142. The first electrode 120, the second electrode 130 and the protrusion structure 140 are disposed on the same side of the device layer 110. More specifically, the first electrode 120, the second electrode 130 and the protrusion structure 140 are disposed on the same side of the body 142, and orthographic projections on the surface 142s of the body 142 do not overlap. In particular, in the present embodiment, a connection line between the first electrode 120 and the second electrode 130 passes through the protrusion structure 140, the connection line is defined by any point on the first electrode 120 and any point on the second electrode 130, further, an orthographic projection of the connection line on the surface 142s passes through the protrusion structure 140, or in other words, an orthographic projection of the connection line on the surface 142s passes through an orthographic projection of the protrusion structure 140 on the surface 142 s.
In the present embodiment, the material of the bump structure 140, the first electrode 120 and the second electrode 130 may be the same, and is selected from gold (Au), tin (Sn), nickel (Ni), titanium (Ti), indium (In), alloys thereof, and combinations thereof, for example, but the invention is not limited thereto. That is, the protrusion structure 140 and the first and second electrodes 120 and 130 can be formed on the same layer, so as to avoid increasing additional production cost. In other embodiments, the material of the protrusion structure 140 may also be selected from a light-transmitting material, such as silicon oxide, silicon nitride, silicon oxynitride, other suitable inorganic materials, or a stacked layer of at least two of the above materials, so as to avoid blocking the forward light of the micro light-emitting device 100.
In the embodiment, the body 142 includes a first type semiconductor layer 111, a light emitting layer 112 and a second type semiconductor layer 113, wherein the light emitting layer 112 is disposed on the first type semiconductor layer 111, and the second type semiconductor layer 113 is disposed on the light emitting layer 112, but the invention is not limited thereto. For example, in the embodiment, the protrusion structure 140 is connected to the second-type semiconductor layer 113, but the invention is not limited thereto.
The first-type and second-type semiconductor layers 111 and 113 may include ii-vi materials, such as zinc selenium (ZnSe), or iii-v nitride materials, such as gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN), indium gallium nitride (InGaN), aluminum gallium nitride (AlGaN), or aluminum indium gallium nitride (AlInGaN). In the present embodiment, the first type semiconductor layer 111 is, for example, an N-type doped semiconductor layer, and the material of the N-type doped semiconductor layer is, for example, N-type gallium nitride (N-GaN). The second type semiconductor layer 113 is, for example, a P-type doped semiconductor layer, and the material of the P-type doped semiconductor layer is, for example, P-type gallium nitride (P-GaN), but the invention is not limited thereto. In the present embodiment, the structure of the light emitting layer 112 is, for example, a multi-Quantum Well (MQW) structure, the multi-Quantum Well structure includes a plurality of layers of indium gallium nitride (InGaN) and a plurality of layers of gallium nitride (GaN) stacked alternately, and the light emitting wavelength range of the light emitting layer 112 can be adjusted by designing the ratio of indium or gallium in the light emitting layer 112, but the invention is not limited thereto.
In the present embodiment, the first electrode 120 penetrates through the second-type semiconductor layer 113 and the light emitting layer 112 to connect to the first-type semiconductor layer 111, and the second electrode 130 connects to the second-type semiconductor layer 113. However, the invention is not limited thereto, and according to other embodiments, the first electrode 120 and the second electrode 130 may be electrically connected to the first type semiconductor layer 111 and the second type semiconductor layer 113 through other conductive layers, respectively. Here, the first electrode 120 is, for example, an N-type electrode, and the second electrode 130 is, for example, a P-type electrode. More specifically, the first electrode 120 and the second electrode 130 have different electrical properties. In the present embodiment, the material of the first electrode 120 and the second electrode 130 is selected from gold (Au), tin (Sn), nickel (Ni), titanium (Ti), indium (In), alloys of the above materials, and combinations thereof, but the invention is not limited thereto.
Referring to fig. 1, in the present embodiment, the micro light emitting device 100 further includes an insulating layer 150 covering the protrusion structure 140, the light emitting layer 112, a portion of the first type semiconductor layer 111 and a portion of the second type semiconductor layer 113. The first electrode 120 penetrates through the insulating layer 150, the second type semiconductor layer 113 and the light emitting layer 112 and is connected to the first type semiconductor layer 111, and the second electrode 130 penetrates through the insulating layer 150 and is connected to the second type semiconductor layer 113. It should be noted that a portion of the insulating layer 150 covering the bump structure 140 can also be regarded as a portion of the bump structure 140, but in an embodiment not shown, the insulating layer 150 can also be omitted. In the present embodiment, the material of the insulating layer 150 is, for example, silicon oxide, silicon nitride, silicon oxynitride, other suitable inorganic materials, or a stacked layer of at least two of the above materials, but the invention is not limited thereto.
In the present embodiment, the vertical height of the protrusion 140 on the surface 100s in the first direction D1 of the surface 142s of the body 142 is a first height H1. The vertical height of any one of the first electrode 120 and the second electrode 130 in the first direction D1 on the surface 142s is a second height H2. For example, the first height H1 of the protrusion structure 140 and the second height H2 of the first electrode 120 or the second electrode 130 may satisfy the following relationship: H1/H2 is 0.8-1.2, wherein less than 0.8 results in poor effect of blocking overflow of the bonding process, and more than 1.2 results in poor yield of the bonding process. The preferred conditions are | H1-H2| ≦ 1 μm, which can effectively avoid overflow of the bonding process and increase the yield of the bonding process, but the invention is not limited thereto. Specifically, the surface 142s of the body 142 refers to the topmost surface of the body 142. In some embodiments, the first height H1 of the protruding structure 140 is less than the second height H2 of any one of the first electrode 120 and the second electrode 130, and satisfies the following relation: (H2-H1)/H1. ltoreq.0.2, and more than 0.2 results in poor effect of blocking the overflow of the joining process. In other embodiments, the first height H1 of the protrusion structure 140 is greater than the second height H2 of any one of the first electrode 120 and the second electrode 130, and satisfies the following relation: (H1-H2)/H1 is less than or equal to 0.2, and more than 0.2 influences the yield of the bonding process.
In the present embodiment, the element layer 110 has a thickness H3 in the first direction D1. For example, the first height H1 of the protrusion structure 140 and the thickness H3 of the device layer 110 may satisfy the following relationship: H1/H3 is 0.01-0.95, wherein, the effect of blocking overflow of the jointing process is not good when the H1/H3 is less than 0.01, and the yield of the jointing process is affected when the H1/H3 is more than 0.95. The preferred implementation condition is 0.3 ≦ H1/H3 ≦ 0.7, which can effectively block the overflow of the bonding process and increase the yield of the bonding process, but the invention is not limited thereto. Referring to fig. 2, in the embodiment, the connection line between the first electrode 120 and the second electrode 130 may be substantially parallel to the second direction D2 (i.e., the extending direction of the cross-section line a-a'), and the second direction D2 is substantially perpendicular to the first direction D1, but the invention is not limited thereto. In the present embodiment, the protrusion structure 140 has a maximum length L1 along the second direction D2, and the first electrode 120 and the second electrode 130 have a distance S1 along the second direction D2. For example, the length L1 of the protrusion structure 140 and the spacing S1 between the first electrode 120 and the second electrode 130 may satisfy the following relation: L1/S1 ≦ 1 of 0.8 ≦ L, and less than 0.8 may result in poor overflow blocking effect, but the present invention is not limited thereto.
In the present embodiment, the element layer 110 has a maximum length L2 in the second direction D2. For example, in the present embodiment, the length L1 of the protrusion structure 140 and the length L2 of the device layer 110 satisfy the following relationship: L1/L2 is less than or equal to 0.8, so as to avoid yield reduction caused by the protrusion structure 140 being too close to the edge of the body 142, but the invention is not limited thereto. In the present embodiment, the bump structure 140 has a maximum width W1 in a third direction D3 perpendicular to the second direction D2, and the element layer 110 has a maximum width W2 in the third direction D3. For example, in the present embodiment, the width W1 of the protrusion structure 140 and the width W2 of the device layer 110 satisfy the following relationship: W1/W2 is not more than 0.8, so as to avoid yield reduction caused by the protrusion structure 140 being too close to the edge of the body 142, but the invention is not limited thereto. Specifically, the first electrode 120 and the second electrode 130 have a maximum width W3 and a maximum width W4 in a third direction D3 perpendicular to the second direction D2, wherein the width W1 is greater than the width W3 and the width W4, respectively, so that the overflow tolerance is better.
In the present embodiment, the element layer 110 has two opposite side edges 110a and 110b, and the distance between the two side edges 110a and 110b is S2. The shortest distance between the protruding structure 140 and either of the two side edges 110a, 110b is S3. For example, in the present embodiment, the spacing S2 between the two side edges 110a and 110b of the device layer 110 and the shortest spacing S3 between the protruding structure 140 and either of the two side edges 110a and 110b satisfy the following relations: 0.01 ≦ S3/S2 ≦ 0.2, which avoids the problem of the bump structure 140 being too close to the two side edges 110a of the device layer 110, such as the leakage of the side wall, and the yield is reduced, but the invention is not limited thereto. In particular, in some preferred embodiments, the shortest distance S3 between the protrusion 140 and either of the two side edges 110a, 110b can be less than or equal to 10 μm.
In the embodiment, the ratio of the orthographic projection area of the protrusion structure 140 on the surface 142s of the body 142 to the surface area of the surface 142s of the body 142 may be less than or equal to 0.8, and a ratio greater than 0.8 may cause the protrusion structure 140 to occupy too much, thereby reducing the overflow tolerance, but the invention is not limited thereto. Although some embodiments of the present invention are specific to describing micro light emitting devices that include p-n diodes, it should be understood that embodiments of the present invention are not so limited, and that some embodiments may also be applied to other micro semiconductor devices, including micro semiconductor devices (e.g., diodes, transistors, integrated circuits) that may be controlled to perform predetermined electronic functions or micro semiconductor devices with photonic functions (e.g., light emitting diodes, laser diodes, photodiodes). Other embodiments of the invention are also applicable to microchips including circuitry, such as microchips with Si or SOI wafers as the material for logic or memory applications, or GaAs wafers as the material for RF communication applications.
Fig. 3 is a schematic cross-sectional view of a micro light-emitting device according to another embodiment of the invention. Referring to fig. 3, a main difference between the micro light emitting device 100A of the present embodiment and the micro light emitting device 100 shown in fig. 1 is that the protrusion structure 140A of the micro light emitting device 100A includes at least a portion of the second type semiconductor layer 113A.
In the embodiment, the first electrode 120A penetrates through the second-type semiconductor layer 113A of the body 142A and the light emitting layer 112A to be electrically connected to the first-type semiconductor layer 111A exposed outside the insulating layer 150, and the second electrode 130A is connected to the second-type semiconductor layer 113A exposed outside the insulating layer 150, but the invention is not limited thereto. In the present embodiment, the first height H1 of the protrusion structure 140A and the thickness H3 of the device layer 110A satisfy the following relationship: H1/H3 is more than or equal to 0.01 and less than or equal to 0.3, so that overflow of the jointing process is effectively blocked and the yield of the jointing process is increased.
Fig. 4 is a schematic cross-sectional view of a micro light-emitting device according to another embodiment of the invention. Referring to fig. 4, a main difference between the micro light emitting device 100B of the present embodiment and the micro light emitting device 100 shown in fig. 1 is that the protrusion structure 140B of the micro light emitting device 100B includes a second type semiconductor layer 113B and a light emitting layer 112B. For example, in the embodiment, the protrusion structure 140B further includes a portion of the first type semiconductor layer 111B, and the body 142B includes a portion of the first type semiconductor layer 111B, but the invention is not limited thereto. In the present embodiment, the light emitting layer 112B is located in the central protruding structure 140B, and the first electrode 120B and the second electrode 130B are disposed on two sides of the protruding structure 140B. Therefore, the current density of the micro light emitting device 100B is concentrated to increase the light emitting efficiency of the micro light emitting device 100B and avoid the side leakage problem.
Specifically, the protrusion 140B and the body 142B in this embodiment can be formed by the same manufacturing method, such as Metal-organic Chemical Vapor Deposition (Metal-organic Chemical Vapor Deposition). Preferably, the first type semiconductor layer 111B, the light emitting layer 112B and the second type semiconductor layer 113B are first completed, and then the protrusion structure 140B and the body 142B are formed by photolithography and etching, respectively, to increase the manufacturing efficiency of the micro light emitting device 100B, but the invention is not limited thereto. In the present embodiment, the first height H1 of the protrusion structure 140B and the thickness H3 of the device layer 110B satisfy the following relationship: H1/H3 is more than or equal to 0.7 and less than or equal to 0.95, wherein the effect of blocking overflow of the jointing process is poor when the ratio is less than 0.7, and the yield of the jointing process is influenced when the ratio is more than 0.95.
In the present embodiment, the first electrode 120B and the second electrode 130B are disposed on the first type semiconductor layer 111B. The micro light-emitting device 100B further includes an insulating layer 160 and a conductive layer 170. The insulating layer 160 partially covers the first type semiconductor layer 111B and the protruding structure 140B. The conductive layer 170 is disposed on the insulating layer 160 and connected to the second-type semiconductor layer 113B of the protrusion 140B exposed outside the insulating layer 160. For example, the second electrode 130B is electrically connected to the second-type semiconductor layer 113B through the conductive layer 170, and the first electrode 120B is connected to the first-type semiconductor layer 111B exposed outside the insulating layer 150B, but the invention is not limited thereto. In the present embodiment, the insulating layer 160 and the insulating layer 150B may be made of the same material, such as silicon oxide, silicon nitride, silicon oxynitride, other suitable inorganic materials, or a stacked layer of at least two of the above materials, but the invention is not limited thereto. In particular, a portion of the insulating layer 150B, the insulating layer 160 and the conductive layer 170 covering the bump structure 140B can also be regarded as a portion of the bump structure 140B.
In the present embodiment, the material of the conductive layer 170 is generally a metal material in consideration of conductivity. However, the invention is not limited thereto, and in some embodiments, other conductive materials may be used for the material of the conductive layer 170, such as an alloy, a nitride of a metal material, an oxide of a metal material, an oxynitride of a metal material, or other suitable materials, or a stacked layer of a metal material and other conductive materials. In other embodiments, the material of the conductive layer 170 may also be a conductive material with high reflectivity, such as silver (Ag), aluminum (Al) or gold (Au), to improve the effective light-emitting intensity of the micro-light-emitting element 100B.
Fig. 5A to 5B are schematic cross-sectional views illustrating a bonding process of the display device 10A according to an embodiment of the invention. Fig. 5A shows a schematic cross-sectional view of a plurality of micro-light emitting elements 100 transferred onto a backplane 11. Referring to fig. 5A, in the present embodiment, a display device 10A includes a plurality of micro light emitting elements 100, a back plate 11, a plurality of first bonding pads 12, and a plurality of second bonding pads 13. The first bonding pads 12 are disposed on the back plate 11 corresponding to the first electrodes 120 of the micro light-emitting devices 100, and the second bonding pads 13 are disposed on the back plate 11 corresponding to the second electrodes 130 of the micro light-emitting devices 100. In the present embodiment, the material of the first bonding pad 12 and the second bonding pad 13 is selected from gold, copper, tin, indium, alloys thereof, and combinations thereof, or solder paste (solder paste), but the invention is not limited thereto. According to other embodiments, the material of the first bonding pad 12 and the second bonding pad 13 may also be Anisotropic Conductive Film (ACF) or other suitable bonding materials.
Fig. 5B is a schematic cross-sectional view of the display device 10A of the present embodiment after the first bonding pads 12 and the second bonding pads 13 are heated and cured. Referring to fig. 5B, after the first bonding pads 12 and the second bonding pads 13 in fig. 5A are heated to a molten state, the first bonding pads 12 and the second bonding pads 13 in the molten state overflow along the surface 11s of the back plate 11, respectively. Wherein the first bonding pads 12 and the second bonding pads 13 flowing toward the protruding structures 140 overflow into between the protruding structures 140 and the back plate 11. In particular, in the present embodiment, the first bonding pads 12 and the second bonding pads 13 overflowing between the protrusion structures 140 and the back plate 11 do not contact each other. That is, the bump structure 140 in the present embodiment can greatly reduce the probability of short circuit caused by overflow when the first bonding pad 12 and the second bonding pad 13 are in a molten state.
After the first bonding pads 12 and the second bonding pads 13 are cooled and cured, the first electrodes 120 of the micro light emitting devices 100 are electrically connected to the back plate 11 through the first bonding pads 12, and the second electrodes 130 of the micro light emitting devices 100 are electrically connected to the back plate 11 through the second bonding pads 13, so as to form the display device 10A of the embodiment. In the embodiment, the orthographic projections of the first bonding pads 12 and the second bonding pads 13 on the back plate 11 are partially overlapped with the orthographic projections of the bump structures 140 on the back plate 11, but the invention is not limited thereto. In some embodiments, orthographic projections of the first bonding pads 12, the second bonding pads 13 and the bump structures 140 on the back plate 11 are staggered from each other.
Specifically, in the present embodiment, the Display device 10A is, for example, a Micro light emitting diode Display (Micro LEDs Display). Depending on its application, the micro light emitting diode display may contain other components. Such other components include (but are not limited to): memory, mould sense screen controller and battery. In other embodiments, the micro light emitting diode display may be a television, a tablet, a telephone, a laptop, a computer monitor, a stand-alone terminal service stand, a digital camera, a handheld game console, a media display, an electronic book display, a vehicle display, or a large area electronic watch display. In addition, compared with the common light emitting diode technology, the micro light emitting element is reduced from millimeter level to micron level, so that the micro light emitting diode display can achieve high resolution, reduce the power consumption of display, and has the advantages of energy conservation, simple mechanism, thinness and the like.
In the embodiment, the back plate 11 is, for example, a pixel array substrate, and the pixel array substrate may be selected from a complementary Metal Oxide semiconductor (cmos) substrate, a liquid Crystal on silicon (lcos) substrate, a thin Film transistor (tft) (thin Film transistor) substrate, or other substrates having a driving circuit. The micro light emitting devices 100 may include micro light emitting diodes with different light emitting wavelength ranges (e.g., red, blue, green), but the invention is not limited thereto.
In the present embodiment, the orthographic projection profile of the convex structure 140 of the micro light-emitting device 100 on the surface 11s of the back plate 11 is rectangular. However, the invention is not limited thereto, and according to other embodiments, the orthographic projection profile of the convex structure 140 of the micro light-emitting element 100 on the surface 11s of the back plate 11 can also be square, circular, diamond or other suitable shapes. It should be noted that, in some embodiments, the orthographic projection profile of the convex structure 140 of the plurality of micro light-emitting elements 100 applied to the display device (e.g. a micro light-emitting diode display) on the surface 11s of the back plate 11 can take different shapes according to different light-emitting wavelength ranges. In this way, the protrusion structures 140 with different appearances can improve the alignment accuracy of different color pixels during the process of transferring the micro light emitting devices to the backplane (e.g., the pixel array substrate).
Fig. 6 is a schematic cross-sectional view of a display device according to another embodiment of the invention. Referring to fig. 6, the difference between the display device 10B of the present embodiment and the display device 10A of fig. 5B is that the top surface 140Ct of the protrusion structure 140C of the micro light emitting device 100C is aligned with the surface 11s of the back plate 11. Therefore, in the bonding process, the first bonding pad 12 and the second bonding pad 13 in the molten state can be completely blocked by the protrusion structure 140C of the micro light emitting device 100C, and the probability of short circuit caused by overflow when the first bonding pad 12 and the second bonding pad 13 are in the molten state can be greatly reduced. It is specifically noted that the bump structure 140C includes the insulating layer 150, but the insulating layer 150 may be omitted, so long as the first bonding pad 12 and the second bonding pad 13 in the molten state are blocked, which is within the scope of the present invention.
Fig. 7 is a schematic cross-sectional view of a display device 10C according to yet another embodiment of the invention. Referring to fig. 7, a difference between the display device 10C of the present embodiment and the display device 10B of fig. 6 is that the back plate 11C has a plurality of grooves 11Ca, and each groove 11Ca is respectively disposed between a set of first bonding pads 12 and a set of second bonding pads 13 corresponding to one micro light emitting device 100D. In the present embodiment, a part of the protrusion structures 140D of the micro light emitting device 100D is disposed in the groove 11Ca of the back plate 11C. Therefore, compared to the display device 10B shown in fig. 6, the display device 10C of the present embodiment can further reduce the probability of short circuit caused by overflow when the first bonding pads 12 and the second bonding pads 13 are in a molten state.
It should be noted that the orthographic projection profile of the groove 11Ca of the back plate 11C on the surface 11Cs of the back plate 11C in this embodiment is, for example, rectangular, but the invention is not limited thereto, and in some embodiments, the orthographic projection profile of the groove 11Ca of the back plate 11C on the surface 11Cs of the back plate 11C may also be square, circular, diamond or other suitable shapes to match the orthographic projection profile of the micro light emitting element 100D on the surface 11Cs of the back plate 11C. That is, the micro light emitting devices 100D (e.g., micro light emitting diodes with different light emitting colors) applied to the display device (e.g., a micro light emitting diode display) can be aligned by using the projection profile of the groove 11Ca on the back plate 11C on the surface 11Cs, so as to improve the alignment accuracy of different color pixels.
In summary, the micro light emitting device and the display apparatus according to the embodiments of the invention have the protrusion structure disposed between the first electrode and the second electrode, so that in the bonding process of transferring the micro light emitting device to the display apparatus, the bonding pad connected to the first electrode and the bonding pad connected to the second electrode are effectively prevented from being conducted due to overflow, thereby improving the production yield of the display apparatus and increasing the design margin of the micro light emitting device.
Although the present invention has been described with reference to the above embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention.
Claims (17)
1. A micro light-emitting device, comprising:
an element layer comprising a body and a raised structure disposed on the body, the body having a surface;
the first electrode is electrically connected with the element layer; and
a second electrode electrically connected to the device layer, wherein the first electrode, the protrusion structure and the second electrode are disposed on the same side of the body, wherein the protrusion structure is disposed between the first electrode and the second electrode, and a connection line between the first electrode and the second electrode passes through the protrusion structure,
wherein the protrusion structure has a first height on the surface, either the first electrode or the second electrode has a second height on the surface, the first height is H1, the second height is H2, and 0.8 ≦ H1/H2 ≦ 1.2,
the maximum length of the convex structure is L1, the distance between the first electrode and the second electrode is S1, and L1/S1 is more than or equal to 0.8 and less than or equal to 1.
2. The micro light-emitting element according to claim 1, wherein the maximum length of the element layer is L2, and L1/L2 ≦ 0.8.
3. The micro light-emitting element according to claim 1, wherein the first height is smaller than the second height, and (H2-H1)/H1 ≦ 0.2.
4. The micro light-emitting element according to claim 1, wherein the first height is greater than the second height, and (H1-H2)/H1 ≦ 0.2.
5. The micro light-emitting element according to claim 1, wherein the element layer has a thickness of H3, and 0.01. ltoreq.H 1/H3. ltoreq.0.95.
6. The micro light-emitting device as claimed in claim 1, wherein the device layer has two opposite side edges, and the distance between the two side edges is S2, the shortest distance between the protrusion structure and either of the two side edges is S3, and 0.01 ≦ S3/S2 ≦ 0.2.
7. The micro light-emitting element according to claim 1, wherein a ratio of an orthographic projection area of the projection structure on the surface of the body to a surface area of the surface of the body is 0.8 or less.
8. The micro light-emitting element of claim 1, wherein the body comprises:
a first type semiconductor layer;
a light emitting layer disposed on the first type semiconductor layer; and
and the second type semiconductor layer is arranged on the luminous layer, wherein the bulge structure is connected with the second type semiconductor layer.
9. The micro light-emitting element according to claim 1, wherein the element layer comprises:
a first type semiconductor layer;
a light emitting layer disposed on the first type semiconductor layer; and
and the second type semiconductor layer is arranged on the luminous layer, wherein the protruding structure comprises at least part of the second type semiconductor layer.
10. The micro light-emitting device as claimed in claim 9, wherein the protrusion structure comprises the second type semiconductor layer, the light-emitting layer and a portion of the first type semiconductor layer.
11. The micro light-emitting element of claim 10, further comprising:
the insulating layer partially covers the first type semiconductor layer and the protruding structures; and
a conductive layer disposed on the insulating layer and connected to the second-type semiconductor layer exposed outside the insulating layer in the protrusion structure,
wherein the second electrode is connected to the conductive layer, and the first electrode is connected to the first type semiconductor layer.
12. The micro light-emitting device of claim 1, wherein the first electrode and the second electrode have different electrical properties.
13. A display device, comprising:
a plurality of micro light-emitting elements comprising:
an element layer comprising a body and a raised structure disposed on the body, the body having a surface;
the first electrode is electrically connected with the element layer; and
the second electrode is electrically connected with the element layer;
wherein the first electrode, the protrusion structure and the second electrode are disposed on the same side of the body, wherein the protrusion structure is located between the first electrode and the second electrode, and a connection line of the first electrode and the second electrode passes through the protrusion structure, the protrusion structure is perpendicular to the surface and has a first height, any one of the first electrode and the second electrode is perpendicular to the surface and has a second height, the first height is H1, the second height is H2, and 0.8 ≤ H1/H2 ≤ 1.2; the maximum length of the convex structure is L1, the distance between the first electrode and the second electrode is S1, and L1/S1 is more than or equal to 0.8 and less than or equal to 1;
a back plate; and
a first bonding pad and a second bonding pad disposed on the back plate,
wherein the first electrode of the micro light-emitting element is electrically connected to the back plate through the first bonding pad, the second electrode of the micro light-emitting element is electrically connected to the back plate through the second bonding pad, and the first bonding pad and the second bonding pad are separated from each other.
14. The display device of claim 13, wherein orthographic projections of the first and second bonding pads on the backplane respectively partially overlap orthographic projections of the raised structures on the backplane.
15. The display device of claim 13, wherein orthographic projections of the first bonding pads, the second bonding pads, and the raised structures on the backplane are offset from one another.
16. The display device of claim 15, wherein a top surface of the raised structures is flush with a surface of the backplane.
17. The display device according to claim 13, wherein the back plate has a groove disposed between the corresponding first bonding pad and the second bonding pad, and a part of the protruding structure of the micro light-emitting element is disposed in the groove of the back plate.
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