Light emitting diode and light emitting device

Abstract

The invention provides a light-emitting diode and a light-emitting device, the light-emitting diode comprises an epitaxial structure, the epitaxial structure comprises a first semiconductor layer, a second semiconductor layer and an active layer, the surface of one side of the first semiconductor layer far away from the active layer is a first table top, and the upper surface of the second semiconductor layer is partially covered by the active layer; and the part, not covered by the active layer, of the upper surface is a second mesa. The first electrode is arranged on the first table top, and the second electrode is arranged on the second table top; wherein the short edge, close to the first electrode, of the second table top is a first edge, the short edge, close to the second electrode, of the second table top is a second edge, a plurality of removal areas are arranged at the second edge, and the depth H1 of each removal area is not smaller than 0.5 micron. According to the invention, the second edge has the morphology which is easy to identify by arranging the plurality of removal areas at the second edge, so that the second electrode can be effectively distinguished through the special morphology when observed from the back surface, thereby facilitating the die bonding process.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor-related technologies, and in particular to a light emitting diode and a light emitting device. Background Art

[0002] Light-emitting diodes have been widely used in solid-state lighting, display, mobile lighting and other fields due to their advantages such as high luminous efficiency, long life and environmental protection.

[0003] Flip-chip LEDs are an effective technical means to further improve the luminous efficiency of LEDs due to their advantages such as no wire bonding, no electrode shading, and excellent heat dissipation. In red light-emitting diodes, the grown epitaxy is usually transferred to a transparent substrate, and a bonding layer is added between the substrate and the epitaxy. In order to further achieve better light output, more and more products choose to pattern the substrate (PSS) to further enable light to be emitted from the back substrate.

[0004] Since red light emitting diodes usually have a thicker P-type layer to improve ESD permeability, when observing the electrode from the back side (usually the substrate side), it is sometimes difficult to distinguish the positive and negative electrodes due to the thicker P-type layer. In order to better emit light, red light emitting diodes sometimes have a PSS patterned substrate as the substrate. Although the patterned substrate and bonding layer are conducive to light emission from the substrate, when observed from the back, due to the poor light transmittance of the patterned substrate, it will be more difficult to distinguish the positive and negative poles of the light emitting diode, which will increase the difficulty in the die bonding process, or require additional steps to identify the position of the positive and negative electrodes, increasing the process cost. Summary of the invention

[0005] The present invention provides a light emitting diode and a light emitting device to solve at least one of the above problems.

[0006] In one aspect, the present invention provides a light emitting diode, comprising: An epitaxial structure comprises a first semiconductor layer, a second semiconductor layer, and an active layer, wherein the active layer is located between the first semiconductor layer and the second semiconductor layer, the surface of the first semiconductor layer away from the active layer is a first table, the upper surface of the second semiconductor layer is partially covered by the active layer, and the portion of the upper surface not covered by the active layer is a second table.

[0007] A first electrode is disposed on the first table surface, and a second electrode is disposed on the second table surface; Among them, the short side edge of the second table near the first electrode is the first edge, the short side edge of the second table near the second electrode is the second edge, and a plurality of removal areas are set at the second edge, and the removal areas extend from the second edge toward the first table. The depth H1 of the removal areas is not less than 0.5 μm, and the depth direction is the direction from the first semiconductor layer to the second semiconductor layer.

[0008] In another aspect, the present invention provides a light emitting device, comprising the light emitting diode mentioned above.

[0009] The light-emitting diode provided by the present invention has a first edge close to the first electrode and a second edge close to the second electrode. By setting a plurality of removal areas at the second edge, the second edge can have an easily identifiable morphology. Therefore, when observed from the back, the second electrode can be effectively distinguished by the special morphology, thereby facilitating the crystal bonding process.

[0010] The light emitting device provided by the present invention has the above-mentioned light emitting diode, and therefore also has the above-mentioned advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a top view of an existing light emitting diode; Figure 2 is a cross-sectional view of the first embodiment of the present invention; Figure 3 A top view of an example of embodiment 1 of the present invention; Figure 4 To further reflect Figure 3 A schematic diagram of parameters of Embodiment 1; Figure 5 is a top view of another example of the first embodiment of the present invention; Figure 6 A top view of an example of the second embodiment of the present invention; Figure 7 is a top view of another example of the second embodiment of the present invention; Figure 8 is a top view of another example of the second embodiment of the present invention; Fig. 9 A top view of an example of the third embodiment of the present invention; Fig.10 is a top view of another example of the third embodiment of the present invention; Fig.11 is a schematic diagram of a light emitting device according to a fourth embodiment of the present invention; Reference numerals: 10 light emitting diode 100 substrate 110 bonding layer 120 epitaxial structure 121 first semiconductor layer 122 active layer 123 second semiconductor layer 131 first electrode 132 second electrode 141 first pad 142 second pad 150 insulating layer T1 first mesa T2 second mesa B1 first edge B2 second edge P removal area 20 light emitting device 21 driving substrate DETAILED DESCRIPTION

[0012] The following specific embodiments illustrate the embodiments of the present invention, and those familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0013] It should be noted that the diagrams provided in the embodiments of the present invention are only used to illustrate the basic concept of the present invention in a schematic manner. Although the diagrams only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, the form, quantity and proportion of each component can be changed at will during actual implementation, and the layout of the components may also be more complex. The structures, proportions, sizes, etc. illustrated in the drawings of the specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions that can be implemented in this application, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by the present invention.

[0014] like Figure 1 As shown, the existing light-emitting diode has a first electrode 131 and a second electrode 132. However, when viewed from above, since the first edge of the short side of the second table T2 close to the first electrode 131 and the second edge of the short side close to the second electrode 132 are completely consistent in morphology, during the crystal bonding process, when observing the electrodes from the back side of the electrodes, it is difficult to distinguish the first electrode 131 and the second electrode 132, which brings certain difficulties to the crystal bonding.

[0015] In order to solve the above problems, the inventors have invented a light emitting diode after experimental design and verification, including: An epitaxial structure, the epitaxial structure comprising a first semiconductor layer, a second semiconductor layer, and an active layer, wherein the active layer is located between the first semiconductor layer and the second semiconductor layer, a surface of the first semiconductor layer away from the active layer is a first table, an upper surface of the second semiconductor layer is partially covered by the active layer, and a portion of the upper surface not covered by the active layer is a second table; A first electrode is disposed on the first table surface, and a second electrode is disposed on the second table surface; Among them, the short side edge of the second table near the first electrode is the first edge, the short side edge of the second table near the second electrode is the second edge, and a plurality of removal areas are set at the second edge, and the removal areas extend from the second edge toward the first table. The depth H1 of the removal areas is not less than 0.5 μm, and the depth direction is the direction from the first semiconductor layer to the second semiconductor layer.

[0016] Optionally, the second semiconductor layer has a thickness H2, and a ratio of a depth H1 of the removed region to the thickness H2 is H1 / H2≥1 / 3.

[0017] Optionally, the direction along the second edge is the X direction, and the removal area has a width D in the X direction at the second edge, where D is ≥ 2 μm and is smaller than the width of the second edge.

[0018] Optionally, the direction perpendicular to the second edge is the Y direction, and the removal area has a maximum length L in the Y direction, and L≥2 μm.

[0019] Optionally, the first mesa and the removal area have a shortest perpendicular distance d, 2 μm≤d≤15 μm.

[0020] Optionally, there are a plurality of removal areas with the same morphology at the second edge.

[0021] Optionally, a plurality of removal areas with the same morphology are arranged at the same interval W.

[0022] Optionally, a plurality of removal regions with the same morphology are arranged at the same interval W, and the interval W ranges from 0 to 30 μm.

[0023] Optionally, the light emitting diode further includes a substrate, and the substrate is a patterned sapphire substrate.

[0024] Optionally, the light emitting diode further includes a bonding layer, which is disposed on the substrate and is an oxide bonding layer.

[0025] The present invention also provides a light-emitting device, comprising any one of the light-emitting diodes described above.

[0026] The present invention is described in detail below with reference to specific embodiments. Embodiment 1

[0027] This embodiment provides a flip-chip light emitting diode. Figure 2The light emitting diode 10 may include a substrate 100, which may be a sapphire substrate. In this embodiment, in order to further enhance the transmission of light from the substrate 100, a patterned sapphire substrate (PSS sapphire substrate) is selected. An epitaxial structure 120 is arranged on the substrate 100, which includes, from top to bottom, a first semiconductor layer 121, an active layer 122, and a second semiconductor layer 123. The first semiconductor layer 121 may be an N-type semiconductor layer, the active layer 122 may be a multi-layer quantum well layer, which may provide red light or infrared light radiation, and the second semiconductor layer 123 may be a P-type semiconductor layer. The N-type semiconductor layer, the multi-layer quantum well layer, and the P-type semiconductor layer are only the basic constituent units of the semiconductor stacking layer. On this basis, the semiconductor stacking layer may also include other functional structural layers that have an optimizing effect on the performance of the light emitting diode, such as an ohmic contact layer or a current spreading layer. In this embodiment, the light emitting diode is preferably a flip-chip light emitting diode, and is preferably a red light diode or an infrared light diode. The material of the active layer 122 is AlGaInP, and the material of the second semiconductor layer 123 is GaP.

[0028] The surface of the first semiconductor layer 121 away from the active layer 122 is a first mesa T1 , the upper surface of the second semiconductor layer 123 is partially covered by the active layer 122 , and the portion of the upper surface not covered by the active layer 122 is a second mesa T2 .

[0029] It also includes a first electrode 131, which is arranged on the first table T1 and electrically connected to the first semiconductor layer 121, and a second electrode 132, which is arranged on the second table T2 and electrically connected to the second semiconductor layer 123. The first electrode 131 and the second electrode 132 can be selected from one or an alloy of Au, Pt, Ti, Ge, Ni, Be.

[0030] This embodiment is a flip-chip light emitting diode, further comprising a first pad 141, which is disposed on the first electrode 131 and electrically connected to the first electrode 131, and a second pad 142, which is disposed on the second electrode 132 and electrically connected to the second electrode 132. The present invention does not exclude the situation where the first electrode 131 and the second electrode 132 include pads. The first pad 141 and the second pad 142 can be one or more of Ti / Al / Ni / Au / Pt / Sn.

[0031] A bonding layer 110 may also be included, and the bonding layer 110 is used to connect the substrate 100 and the epitaxial structure 120. In some embodiments, in order to enhance the ability of light to be emitted from the substrate 100, the bonding layer 110 may be etched into a concave-convex shape. Furthermore, the bonding layer 110 may be a transparent oxide bonding layer, such as aluminum oxide or silicon oxide or a combination thereof, to increase a more suitable refractive index, thereby forming a refractive index change with the substrate 100, which is more conducive to the emission of light. In this embodiment, the substrate 100 is sapphire with a refractive index of 1.7, and the bonding layer 110 is silicon oxide with a refractive index of 1.45. Such a refractive index is conducive to the light generated by the epitaxial structure 120 to be emitted from the substrate 100 through the bonding layer 110. This embodiment also includes an insulating layer 150, which can protect the epitaxial structure 120. The insulating layer 150 can be a single-layer structure, such as magnesium fluoride or silicon nitride, or a multi-layer structure, such as a DBR reflector composed of SiO2 and TiO2, or a combination of at least two of a variety of structures such as magnesium fluoride, silicon nitride, SiO2, TiO2, ZnO2, ZrO2, Cu2O3, etc. In this embodiment, the insulating layer 150 is a combination of magnesium fluoride and a DBR reflector, which can enhance the reflection of light and effectively protect the epitaxial structure 120.

[0032] refer to Figure 3 The short side edge of the second mesa T2 close to the first electrode 131 is the first edge B1, and the short side edge of the second mesa T2 close to the second electrode 132 is the second edge B2. In the present invention, a plurality of removal areas P are provided at the second edge B2. Figure 2 , Figure 3 The removed area P represents that the portion of the second semiconductor layer 123 is removed. Therefore, from a top view, a special morphology can be observed at the second edge B2, thereby identifying the position of the second electrode 132. The removed area P extends from the second edge B2 toward the first mesa T1. Figure 2 As shown, the removal area P has a depth H1 from the first semiconductor layer 121 to the second semiconductor layer 123, and the value of the depth H1 is not less than 0.5μm. The size of this value affects the observability of the removal area P. If the value is too small, such as less than 0.5μm, the depth of the removal area is too shallow, and it is difficult to distinguish the different graphic appearances at the second edge B2 from a top view, so that it is difficult to distinguish the first electrode 131 and the second electrode 132. Preferably, H1>2μm, in this embodiment, the value of H1 is 5μm. In this embodiment, the morphology of the removal area P can be an arc when viewed from above.

[0033] refer to Figure 2, the second semiconductor layer 123 has a thickness H2, and the depth H1 of the removal area and the thickness H2 of the second semiconductor layer 123 have a ratio H1 / H2. In some embodiments, the ratio H1 / H2 ≥ 1 / 3. The ratio indicates the significance of the removal area P at the second edge B2. The larger the value, the deeper the removal area P is, and the easier it is to observe and identify, so as to determine the position of the second electrode 132. Preferably, the value H1 / H2 ≥ 2 / 3. In this embodiment, the value H1 / H2 ≥ 4 / 5. In some embodiments, the ratio can be 1, that is, the depth H1 of the removal area P is consistent with the thickness H2 of the second semiconductor layer 123.

[0034] refer to Figure 4 , the direction along the second edge B2 is the X direction, and the removal area P has a width D in the X direction at the second edge B2. In some embodiments, D ≥ 2 μm and is smaller than the width of the second edge B2. The width D also reflects the observability of the removal area P. If the value is too small, it is difficult to observe. At the same time, D should be smaller than the width of the second edge B2, otherwise the second edge B2 is completely removed. From a top view, the edge is still flat and cannot be distinguished from the first edge B1. Preferably, D ≥ 10 μm.

[0035] The direction perpendicular to the second edge B2 is the Y direction, and the removal area P has a maximum length L in the Y direction. In some embodiments, L≥2 μm, so that the removal area P is more obvious and easier to observe and identify the second electrode 132. Preferably, L≥5 μm.

[0036] Furthermore, the first mesa T1 and the removal area P have a shortest perpendicular distance d. In some embodiments, 2μm≤d≤15μm. If the value is too small, such as less than 2μm, the removal area P is too close to the first mesa T1, which may easily damage the first mesa T1 and the second electrode 132. If the value is too large, such as greater than 15μm, the removal area P is too far away from the removal area P, thereby affecting the identifiability of the second electrode 132.

[0037] Figure 3 In the figure, the shape of the removal area P is an arc shape when viewed from above, but the present invention is not limited to this. The shape of the removal area P can also be a square, a semicircle, a triangle or other shapes.

[0038] Figure 5 A square removal area P is shown. Embodiment 2

[0039] like Figure 6 , Figure 7 , Figure 8As shown, in some embodiments, the second edge B2 has multiple removal areas P with the same morphology. Such removal areas P can form a cluster, which is more convenient for observation. During the solid crystal process, when observing the electrode from the back, the second electrode 132 can be effectively distinguished by the special morphology at the second edge B2. Embodiment 3

[0040] Embodiment 3 is obtained on the basis of embodiment 2.

[0041] like Fig. 9 As shown, in some embodiments, multiple removal areas P of the same morphology are arranged at the same interval W. Furthermore, W can range from 0 to 30 μm. If it exceeds 30 μm, the array period will be unclear and difficult to observe. Preferably, W can be 0-15 μm.

[0042] like Fig.10 As shown, in some embodiments, the interval W may be 0, that is, a plurality of removal areas P with the same morphology are closely arranged together.

[0043] In this embodiment, a plurality of removal areas P arranged at the same interval W are provided. The removal areas P can form a more prominent array, which is beneficial for identifying the second edge B2 and further distinguishing the second electrode 132 . Embodiment 4

[0044] like Fig.11 As shown, the present invention further provides a light emitting device 20, which has a driving substrate 21, and a plurality of light emitting diodes 10 are arranged on the driving substrate 21. The light emitting diodes 10 are any one of the light emitting diodes mentioned above or a combination thereof.

[0045] In summary, the present invention provides a light emitting diode 10, which is different from conventional light emitting diodes (such as Figure 1 ), the present invention provides several embodiments, in which several significant removal areas are set at the second edge to obtain a special morphology. Therefore, when observed from the back, the position of the second edge B2 can be identified by the special morphology, thereby effectively distinguishing the first electrode 131 from the second electrode 132, thereby facilitating the crystal bonding process.

[0046] The present invention further provides a light emitting device 20, which is equipped with the above-mentioned light emitting diode 10 and thus also has the above-mentioned advantages.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A light emitting diode, characterized in that: include: An epitaxial structure, the epitaxial structure comprising a first semiconductor layer, a second semiconductor layer, and an active layer, the active layer being located between the first semiconductor layer and the second semiconductor layer, the surface of the first semiconductor layer away from the active layer being a first mesa, the upper surface of the second semiconductor layer being partially covered by the active layer, and the portion of the upper surface not covered by the active layer being a second mesa; A first electrode is disposed on the first table surface, and a second electrode is disposed on the second table surface; Among them, the short side edge of the second mesa close to the first electrode is the first edge, the short side edge of the second mesa close to the second electrode is the second edge, and a plurality of removal areas are arranged at the second edge, and the removal areas extend from the second edge toward the first mesa, and the depth H1 of the removal areas is not less than 0.5 μm, and the depth direction is the direction from the first semiconductor layer to the second semiconductor layer.

2. A light emitting diode according to claim 1, characterized in that The second semiconductor layer has a thickness H2, and a ratio of a depth H1 of the removal area to the thickness H2 is H1 / H2 ≥ 1 / 3.

3. A light emitting diode according to claim 1, characterized in that , the direction along the second edge is the X direction, and the removal area has a width D in the X direction at the second edge, D≥2μm, and is smaller than the width of the second edge.

4. A light emitting diode according to claim 1, characterized in that , the direction perpendicular to the second edge is the Y direction, and the removal area has a maximum length L in the Y direction, L≥2μm.

5. A light emitting diode according to claim 4, characterized in that , the first table and the removal area have a shortest perpendicular distance d, 2μm≤d≤15μm.

6. A light emitting diode according to claim 1, characterized in that , the second edge has multiple removal areas with the same morphology.

7. A light emitting diode according to claim 6, characterized in that: The plurality of removal areas with the same morphology are arranged at the same interval W.

8. A light emitting diode according to claim 7, characterized in that: The removed areas with the same morphology are arranged at the same interval W, and the range of W is 0-30 μm.

9. The light emitting diode according to claim 1, characterized in that: The light emitting diode further comprises a substrate, which is a patterned sapphire substrate.

10. The light emitting diode according to claim 9, characterized in that: The light emitting diode further comprises a bonding layer, which is arranged on the substrate and is an oxide bonding layer.

11. A light emitting device, characterized in that: A light emitting diode comprising any one of items 1-10 above.

Images