Light-emitting diode structure

Abstract

A light-emitting diode structure includes a metal reflective layer, a first transparent conductive layer, a dielectric layer, a plurality of second transparent conductive layers, a first semiconductor layer, an active layer, and a second semiconductor layer. The metal reflective layer has a plurality of first recessed areas, and each first recessed area has a bump. The first transparent conductive layer is conformally formed on these first recessed areas and bumps of the metal reflective layer. The dielectric layer is formed on the first transparent conductive layer and has a plurality of second recessed areas, and each second recessed area has a through hole for exposing the area of the first transparent conductive layer aligned with the bump. The plurality of second transparent conductive layers are respectively located in these second recessed areas and are connected to the first transparent conductive layer through the through holes. The first semiconductor layer, the active layer, and the second semiconductor layer are sequentially formed on the dielectric layer and these second transparent conductive layers.

Description

Technical Field

[0001] The present invention relates to a light emitting diode structure. Background Art

[0002] A light emitting diode (LED) is a light emitting element made of semiconductor material, which can convert electrical energy into light. It has the advantages of small size, high energy conversion efficiency, long life, power saving, etc., and thus is widely used as a light source for various electronic devices.

[0003] A light emitting diode with a metal reflective layer often fails to achieve better light extraction efficiency due to structural factors. In view of this, suppliers need various solutions to improve the light reflection efficiency of the metal reflective layer. Summary of the Invention

[0004] The present invention proposes an innovative diode packaging structure and its manufacturing method to solve the problems of the prior art.

[0005] In some embodiments of the present invention, a light emitting diode structure includes a metal reflective layer, a first transparent conductive layer, a dielectric layer, a plurality of second transparent conductive layers, a first semiconductor layer, an active layer, and a second semiconductor layer. The metal reflective layer has a plurality of first recessed areas, and each first recessed area has a bump. The first transparent conductive layer is conformally formed on these first recessed areas and bumps of the metal reflective layer. The dielectric layer is formed on the first transparent conductive layer and has a plurality of second recessed areas, and each second recessed area has a through hole for exposing the area of the first transparent conductive layer aligned with the bump. The plurality of second transparent conductive layers are respectively located in these second recessed areas and are connected to the first transparent conductive layer through the through holes. The first semiconductor layer, the active layer, and the second semiconductor layer are sequentially formed on the dielectric layer and these second transparent conductive layers.

[0006] In some embodiments of the present invention, these second transparent conductive layers have a larger grain size than the first transparent conductive layer.

[0007] In some embodiments of the present invention, the total area of these second transparent conductive layers is less than one-third of the area of the first transparent conductive layer.

[0008] In some embodiments of the present invention, the second recessed area is smaller than the first recessed area.

[0009] In some embodiments of the present invention, each second transparent conductive layer is smaller than the first recessed area.

[0010] In some embodiments of the present invention, the size of the through hole is less than or equal to the area of each second transparent conductive layer.

[0011] In some embodiments of the present invention, the grain size of these second transparent conductive layers is 2 to 5 times that of the first transparent conductive layer.

[0012] In some embodiments of the present invention, a light-emitting diode structure includes a metal reflective layer, a first transparent conductive layer, a dielectric layer, a plurality of second transparent conductive layers, a first semiconductor layer, an active layer, and a second semiconductor layer. The metal reflective layer has a plurality of first recessed regions. The first transparent conductive layer is conformally formed on these first recessed regions of the metal reflective layer. The dielectric layer is formed on the first transparent conductive layer and has a plurality of through holes for exposing the first transparent conductive layer. The plurality of second transparent conductive layers are formed on the dielectric layer and are connected to the first transparent conductive layer through the through holes, wherein a local portion of each second transparent conductive layer connected to the first transparent conductive layer forms a T-shaped cross-section within each first recessed region. The first semiconductor layer, the active layer, and the second semiconductor layer are sequentially formed on the dielectric layer and these second transparent conductive layers.

[0013] In some embodiments of the present invention, these second transparent conductive layers have a larger grain size than the first transparent conductive layer.

[0014] In some embodiments of the present invention, the total area of these second transparent conductive layers is less than one-third of the area of the first transparent conductive layer.

[0015] In some embodiments of the present invention, each first recessed region has a bump that is aligned with the corresponding through hole.

[0016] In some embodiments of the present invention, each first recessed region has a bump that connects to the T-shaped cross-section.

[0017] In summary, for the light-emitting diode structure of the present invention, the area of the relatively rough transparent conductive layer is reduced so that it can still perform its ohmic contact function, while covering a relatively thick dielectric layer to reduce the rough surface. Another transparent conductive layer with a smoother surface is covered on the dielectric layer and is connected to the relatively rough transparent conductive layer through the through holes on the dielectric layer, so that the subsequently formed metal reflective layer has a larger flat area, thereby increasing the light reflection efficiency and improving the light extraction efficiency.

[0018] The following will describe the above description in detail by way of embodiments and provide a further explanation of the technical solution of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To make the above and other objects, features, advantages and embodiments of the present invention more obvious and understandable, the description of the accompanying drawings is as follows:

[0020] Figure 1 is a cross-sectional view showing a light-emitting diode structure according to some embodiments of the present invention; and

[0021] Figures 2-9 It is a cross-sectional view showing a method of manufacturing a light-emitting diode structure according to some embodiments of the present invention.

[0022]

Symbol Explanation

[0023] To make the above and other objects, features, advantages and embodiments of the present invention more obvious and understandable, the description of the attached symbols is as follows:

[0024] 100: Light-emitting diode structure

[0025] 102: Substrate

[0026] 102a: Back metal layer

[0027] 104: Conductive bonding layer

[0028] 106: Metal reflective layer

[0029] 106a: Recessed area

[0030] 106b: Bump

[0031] 108: Transparent conductive layer

[0032] 108a: Raised area

[0033] 110: Dielectric layer

[0034] 110a: Recessed area

[0035] 110b: Through hole

[0036] 112: Transparent conductive layer

[0037] 114: Semiconductor layer

[0038] 116: Active layer

[0039] 118: Semiconductor layer

[0040] 118a: Rough surface

[0041] 120a: Metal electrode layer

[0042] 120b: Metal electrode layer

[0043] 120c: Metal electrode layer

[0044] 122: Native substrate Detailed implementation

[0045] To make the description of the present invention more detailed and complete, reference may be made to the accompanying drawings and the various embodiments described below. The same numbers in the drawings represent the same or similar elements. On the other hand, well-known elements and steps are not described in the embodiments to avoid unnecessary limitations on the present invention.

[0046] In the embodiments and claims, the description of "electrically connected" may generally refer to an element being indirectly electrically coupled to another element through other elements, or an element being directly electrically connected to another element without passing through other elements.

[0047] In the embodiments and claims, unless otherwise specifically defined in the context for articles, "a" and "the" may generally refer to a single one or more.

[0048] Please refer to Figure 1 , which shows a cross-sectional view of a light-emitting diode structure according to some embodiments of the present invention. The light-emitting diode structure 100 includes a substrate 102, a metal reflective layer 106, a transparent conductive layer 108, a dielectric layer 110, a transparent conductive layer 112, a semiconductor layer 114, an active layer 116, and a semiconductor layer 118. In some embodiments of the present invention, the material of the metal reflective layer 106 may include copper (Cu), aluminum (Al), indium (In), ruthenium (Ru), tin (Sn), gold (Au), platinum (Pt), zinc (Zn), silver (Ag), titanium (Ti), lead (Pb), nickel (Ni), chromium (Cr), magnesium (Mg), palladium (Pd), or a combination thereof, but is not limited thereto. In some embodiments of the present invention, the metal reflective layer 106 has a plurality of recessed areas 106a, and each recessed area 106a has a bump 106b. In some embodiments of the present invention, the transparent conductive layer 108 is conformally formed on these recessed areas 106a and bumps 106b of the metal reflective layer 106. The material of the transparent conductive layer 108 may include transparent conductive oxide (TCO) or thin-layer metal. For example, the transparent conductive oxide may include indium oxide (In2O3), indium tin oxide (ITO), tin oxide (SnO2), zinc oxide (ZnO), aluminum zinc oxide (AZO), or indium zinc oxide (IZO), but is not limited thereto. The thin-layer metal may include copper (Cu), aluminum (Al), indium (In), ruthenium (Ru), tin (Sn), gold (Au), platinum (Pt), zinc (Zn), silver (Ag), titanium (Ti), lead (Pb), nickel (Ni), chromium (Cr), magnesium (Mg), palladium (Pd), or a combination thereof, but is not limited thereto.

[0049] In some embodiments of the present invention, a dielectric layer 110 is formed on the transparent conductive layer 108 and has a plurality of recessed regions 110a. Each recessed region 110a has a through hole 110b for exposing the raised region 108a of the transparent conductive layer 108 that aligns with the bump 106b. In some embodiments of the present invention, a plurality of transparent conductive layers 112 are respectively located within these recessed regions 110a and are connected to the raised region 108a of the transparent conductive layer 108 through the through holes 110b.

[0050] In some embodiments of the present invention, a semiconductor layer 114, an active layer 116, and a semiconductor layer 118 are sequentially formed on the dielectric layer 110 and these transparent conductive layers 112. A part of the light emitted by the excited active layer 116 is directly output through the upper surface of the semiconductor layer 118, and another part is reflected by the metal reflective layer 106 and then output through the upper surface of the semiconductor layer 118.

[0051] In some embodiments of the present invention, the transparent conductive layer 108 has a smaller grain size, so the surface is smoother. The metal reflective layer 106 formed in contact with the transparent conductive layer 108 also forms a smoother surface, which is beneficial for reflecting the light emitted by the active layer 116 and making the light extraction efficiency of the light-emitting diode structure better.

[0052] In some embodiments of the present invention, the transparent conductive layer 112 has a larger grain size and serves as an ohmic contact layer with the semiconductor layer 114. Therefore, the transparent conductive layer 112 has a larger grain size than the transparent conductive layer 108.

[0053] In some embodiments of the present invention, the total area of the plurality of transparent conductive layers 112 is less than one-third of the area of the transparent conductive layer 108, so that the influence of the transparent conductive layer 112 with a larger grain size on light extraction can be reduced, but it is not limited thereto.

[0054] In some embodiments of the present invention, the area of the recessed region 110a is less than the area of the recessed region 106a, but it is not limited thereto. In some embodiments of the present invention, the area of each transparent conductive layer 112 is less than the area of the corresponding recessed region 106a, but it is not limited thereto.

[0055] In some embodiments of the present invention, the size of the through hole 110b is less than or equal to the area of each transparent conductive layer 112. In some embodiments of the present invention, the grain size of these transparent conductive layers 112 is 2 to 5 times the grain size of the transparent conductive layer 108, but it is not limited thereto.

[0056] In some embodiments of the present invention, a T-shaped cross-section is formed locally in each recessed area 106a of the metal reflective layer 106 where each transparent conductive layer 112 is connected to the transparent conductive layer 108. In some embodiments of the present invention, the bump 106b in the recessed area 106a is connected to the above-mentioned T-shaped cross-section.

[0057] Please refer to Figures 2-9 , which shows a cross-sectional view of a method for manufacturing a light-emitting diode structure according to some embodiments of the present invention. In Figure 2 , on a native substrate 122, a semiconductor layer 118, an active layer 116, and a semiconductor layer 114 are sequentially formed. In some embodiments of the present invention, the semiconductor layer 118 may be an N-type semiconductor layer, the active layer 116 may be a multiple-quantum well (MQW), and the semiconductor layer 114 may be a P-type semiconductor layer.

[0058] In Figure 3 , a transparent conductive film is formed on the surface of the semiconductor layer 114 and patterned into a plurality of transparent conductive layers 112, serving as an ohmic contact layer with the semiconductor layer 114. In some embodiments of the present invention, the shape (top view shape) of each transparent conductive layer 112 may be circular or any polygon. In some embodiments of the present invention, the thickness of the transparent conductive layer 112 is at least 30 angstroms or more, but is not limited thereto. The transparent conductive layer 112 has the characteristics of a larger grain size and a larger surface roughness, serving as an ohmic contact layer with the semiconductor layer 114.

[0059] In Figure 4 , a dielectric layer 110 is conformally formed on the semiconductor layer 114 and the plurality of transparent conductive layers 112, thereby forming a plurality of recessed areas 110a for accommodating the transparent conductive layers 112, and through holes 110b are formed in each recessed area 110a. In some embodiments of the present invention, the thickness of the dielectric layer 110 is at least 400 angstroms or more, but is not limited thereto. The relatively thick dielectric layer 110 prevents the characteristic of the larger surface roughness of the transparent conductive layer 112 from being presented on the dielectric layer 110.

[0060] In Figure 5 , a transparent conductive layer 108 is conformally formed on the surface of the dielectric layer 110, forming a raised area 108a, and the raised area 108a is connected to the transparent conductive layer 112 through the through hole 110b. In some embodiments of the present invention, the thickness of the transparent conductive layer 108 is at least 50 angstroms or more, but is not limited thereto.

[0061] In Figure 6In [description], a metal reflective layer 106 is formed on the surface of the transparent conductive layer 108, thereby forming a plurality of recessed areas 106a and bumps 106b of the metal reflective layer 106, and the bumps 106b are located within each recessed area 106a. Since the grain size of the transparent conductive layer 108 is small and its surface is relatively smooth (compared with the transparent conductive layer 112), the metal reflective layer 106 in contact therewith thus has a relatively flat and smooth surface for reflecting light.

[0062] In Figure 7 [description], a conductive bonding layer 104 is used to bond the metal substrate 102.

[0063] In Figure 8 In Figure 7 the completed structure is turned upside down, and the native substrate 122 is removed.

[0064] In Figure 9 [description], a multi-metal electrode layer (120a, 120b, 120c) is formed on the semiconductor layer 118, and a back metal layer 102a is formed under the metal substrate 102.

[0065] Referring to Figure 1 , finally, a rough surface 118a is formed on the surface of the semiconductor layer 118 to increase the light extraction efficiency, and the light-emitting diode structure 100 is completed.

[0066] For the light-emitting diode structure of the present invention, the area of the relatively rough transparent conductive layer is reduced so that it can still perform its ohmic contact function, while covering a thicker dielectric layer to reduce roughness. Another transparent conductive layer with a finer and smoother surface is covered on the dielectric layer and is connected to the relatively rough transparent conductive layer through a through hole in the dielectric layer, so that the subsequently formed metal reflective layer has a larger flat area, thereby increasing the light reflection efficiency and improving the light extraction efficiency.

[0067] Although the present invention has been disclosed as above in embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the appended claims.

Claims

1. A light-emitting diode structure, characterized in that, Comprising: A metal reflective layer having a plurality of first recessed areas, and each of the first recessed areas has a bump; A first transparent conductive layer conformally formed on the plurality of first recessed areas and the bumps of the metal reflective layer; A dielectric layer formed on the first transparent conductive layer and having a plurality of second recessed areas, and each of the second recessed areas has a through hole for exposing an area of the first transparent conductive layer aligned with the bump; A plurality of second transparent conductive layers respectively located in the plurality of second recessed areas and connected to the first transparent conductive layer through the through holes, and the plurality of second transparent conductive layers have a larger grain size than the first transparent conductive layer; and A first semiconductor layer, an active layer and a second semiconductor layer are sequentially formed on the dielectric layer and the plurality of second transparent conductive layers.

2. The light-emitting diode structure according to claim 1, wherein The total area of the plurality of second transparent conductive layers is less than one-third of the area of the first transparent conductive layer.

3. The light-emitting diode structure according to claim 1, characterized in that, The second recessed area is smaller than the first recessed area.

4. The light-emitting diode structure according to claim 1, characterized in that Each of the second transparent conductive layers is smaller than the first recessed area.

5. The light-emitting diode structure according to claim 1, wherein The size of the through hole is less than or equal to the area of each of the second transparent conductive layers.

6. The light-emitting diode structure according to claim 1, characterized in that, The grain size of the plurality of second transparent conductive layers is 2 to 5 times that of the first transparent conductive layer.

7. The light-emitting diode structure according to claim 3, wherein It further comprises a metal electrode layer on the second semiconductor layer and a back metal layer under the metal reflective layer.

8. The light emitting diode structure according to claim 7, wherein The metal electrode layer and the plurality of second transparent conductive layers do not overlap in the vertical direction.

9. The light-emitting diode structure according to claim 7, wherein, It further comprises a conductive bonding layer between the back metal layer and the metal reflective layer.

10. A light-emitting diode structure, characterized in that, Comprising: A metal reflective layer having a plurality of first recessed areas; A first transparent conductive layer conformally formed on the plurality of first recessed areas of the metal reflective layer; A dielectric layer formed on the first transparent conductive layer and having a plurality of through holes for exposing the first transparent conductive layer; A plurality of second transparent conductive layers formed on the dielectric layer and connected to the first transparent conductive layer through the plurality of through holes, wherein a local part of each of the second transparent conductive layers connected to the first transparent conductive layer forms a T-shaped cross-section in each of the first recessed areas, and the plurality of second transparent conductive layers have a larger grain size than the first transparent conductive layer; and A first semiconductor layer, an active layer and a second semiconductor layer are sequentially formed on the dielectric layer and the plurality of second transparent conductive layers.

11. The light-emitting diode structure according to claim 10, characterized in that, The total area of the plurality of second transparent conductive layers is less than one-third of the area of the first transparent conductive layer.

12. The light-emitting diode structure according to claim 10, wherein, Each of the first recessed areas has a bump, and the bump is aligned with the corresponding through hole.

13. The light emitting diode structure according to claim 10, wherein Each of the first recessed areas has a bump, and the bump is connected to the T-shaped cross-section.

Images