A vertical light emitting diode structure

Abstract

The present application is a vertical light emitting diode structure, which comprises a light emitting diode element, a sidewall insulation layer, a soldering electrode and a metal protection layer. The metal protection layer is electrically connected to the soldering electrode, and covers the crystal grain side edge and the carrier side edge of the light emitting diode element through the sidewall insulation layer. In this way, the potential failure of the sidewall insulation layer during the electroplating or chemical plating process and other harsh processes can be solved by the covering protection of the metal protection layer. In addition, the metal protection layer can provide test points to evaluate the quality of the sidewall insulation layer by detecting the forward bias voltage (Vf) and reverse leakage current (Ir) of the light emitting diode element.

Description

Technical Field

[0001] This invention relates to light-emitting diode (LED) structures, and more particularly to a vertical LED structure having a testable and protective metal layer on the sidewalls. Background Technology

[0002] A conventional vertical light-emitting diode (LED) has a chip structure comprising an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer forming a sandwich structure. Under the P-type semiconductor layer, a mirror layer, a buffer layer, a bonding layer, a silicon substrate, and a P-type electrode are sequentially disposed. The surface of the N-type semiconductor layer can be roughened to increase the light emissivity and to accommodate the N-type electrode. Accordingly, when a voltage is applied to the N-type electrode and the P-type electrode, the N-type semiconductor layer provides electrons, and the P-type semiconductor layer provides holes. The electrons and holes combine in the light-emitting layer to generate light.

[0003] When moisture or conductive material adheres to the PN junction of a vertical LED chip, it may cause the device to fail after being powered on. Therefore, vertical LEDs are generally made with an insulating sidewall layer (passivation), which is usually a SiO2 layer with a thickness of 0.1 micrometers (µm) to 1 micrometer (µm) to protect the PN junction of the chip and prevent potential moisture or conductive material from adhering.

[0004] The coating quality of the insulating sidewall layer of vertical LEDs is difficult to control and verify, and microcracks often appear. However, under poor process conditions, increasing the thickness will not improve the quality and may even cause peeling. But for conventional vertical LEDs, the subsequent packaging process mostly uses die bonding and wire bonding processes, so it has little impact. Moreover, once the vertical LED has completed the packaging process, the die of the vertical LED is already well protected, and the quality of the insulating sidewall layer coating has almost no effect.

[0005] However, when subsequent packaging processes involve stringent procedures such as electroplating or chemical plating, if a defective die with a faulty insulating sidewall layer is placed in the electroplating or chemical plating process, metal ions in the electrolyte can enter through these micro-cracks and adhere to the PN junction. This can cause the vertical LED to fail in subsequent processes, resulting in reduced reliability and a significant increase in cost and product risk. Summary of the Invention

[0006] Therefore, the main objective of this invention is to disclose a vertical light-emitting diode (LED) structure with a metal layer coating. This metal layer can be used to test the density and quality of the external insulating layer at the four PN junctions on the sides of the chip in the vertical LED structure. Simultaneously, this stable metal layer also prevents potential moisture adhesion in subsequent processes and avoids conductive materials adhering to the PN junctions.

[0007] This invention relates to a vertical light-emitting diode (LED) structure, comprising an LED element, a sidewall insulating layer, a welding electrode, and a metal protective layer. The LED element includes a conductive substrate and an LED die, the LED die being formed on the conductive substrate. The LED die has an upper edge and a side edge, the side edge connecting to and surrounding the upper edge of the LED die.

[0008] The conductive substrate has a side edge and an upper edge, the side edge of the substrate connecting to the die side edge, and the upper edge of the substrate connecting to the side edge of the substrate, with no LED die above the upper edge of the substrate. A sidewall insulating layer covers the upper edge of the die, the die side edge, and the side edge of the substrate, and the sidewall insulating layer has a first electrode exposed area at the upper edge of the die, which exposes the LED die.

[0009] The welding electrode passes through the exposed area of ​​the first electrode and is electrically connected to the light-emitting diode chip. The metal protective layer is electrically connected to the welding electrode, and the metal protective layer covers and protects the chip side edge and the carrier plate side edge through the sidewall insulating layer.

[0010] Accordingly, the present invention covers the upper edge of the grain, the side edge of the grain and the side edge of the carrier plate with the metal protective layer, thereby preventing moisture and conductive materials from adhering to the PN junction of the light-emitting diode element.

[0011] Furthermore, the fine and dense coating layer of the metal protective layer forms a good barrier layer, which can solve the potential failure problem of the sidewall insulation layer of the light-emitting diode element in electroplating or chemical plating processes and other harsh environmental processes.

[0012] Furthermore, the metal protective layer can provide test contacts to evaluate the quality of the sidewall insulation layer by detecting the forward bias voltage (Vf) and reverse leakage current (Ir) of the light-emitting diode element.

[0013] More specifically, the metal protective layer is applied to the outside of the sidewall insulating layer by means of depositing a thin metal film (such as metal evaporation, metal sputtering, etc.). If the sidewall insulating layer on the outside of the PN junction itself has cracks and defects, the deposited metal will seep into the PN junction sidewall during the subsequent application of the metal protective layer. This will cause leakage or conduction in the device, and such defective devices can be detected by LED chip electrical testing, thus allowing devices with poor sidewall insulating layers to be eliminated at the chip stage. At the same time, a metal with better stability can be selected for the metal protective layer, making the sidewall of the LED chip PN junction more stable in subsequent processes. Attached Figure Description

[0014] Figure 1 This is a cross-sectional view of the structure of the first embodiment of the present invention;

[0015] Figure 2 This is a cross-sectional view of the subsequent process structure in the first embodiment of the present invention;

[0016] Figure 3 This is a cross-sectional view of the structure of the second embodiment of the present invention;

[0017] Figure 4 This is a cross-sectional view of the structure according to the third embodiment of the present invention. Detailed Implementation

[0018] To gain a deeper understanding and appreciation of the features, objectives, and effects of this invention, a preferred embodiment is described below in conjunction with the accompanying drawings:

[0019] Please see " Figure 1 The figure shown is a cross-sectional view of the structure of the first embodiment of the present invention. The present invention discloses a vertical light-emitting diode structure, which includes a light-emitting diode element 10, a sidewall insulating layer 40, a welding electrode 50 and a metal protective layer 60.

[0020] The light-emitting diode (LED) element 10 includes a conductive substrate 20 and an LED chip 30, the LED chip 30 being formed on the conductive substrate 20. The LED chip 30 has an upper edge 301 and a side edge 302, the side edge 302 being connected to the upper edge 301 and surrounding the LED chip 30. The conductive substrate 20 has a side edge 201 and an upper edge 202, the side edge 201 being connected to the side edge 302, and the upper edge 202 being connected to the side edge 201, with no LED chip 30 above the upper edge 202.

[0021] The sidewall insulating layer 40 covers the upper edge 301 of the die, the side edge 302 of the die, and the side edge 201 of the carrier plate. The sidewall insulating layer 40 has a first electrode exposed area 401 at the upper edge 301 of the die, which exposes the light-emitting diode die 30. The thickness of the sidewall insulating layer 40 is about 0.5 micrometers (µm).

[0022] The welding electrode 50 passes through the first electrode exposed area 401 and is electrically connected to the light-emitting diode chip 30. In one embodiment, the light-emitting diode chip 30 may include a first metal contact layer 31, a first electrical semiconductor layer 32, an active layer 33, and a second electrical semiconductor layer 34 stacked in sequence, and the thickness of the light-emitting diode chip 30 is approximately 3 micrometers (µm). The welding electrode 50 is electrically connected to the second electrical semiconductor layer 34. The conductive carrier 20 includes a metal electrode 21, a conductive bulk material 22, and a metal connection layer 23 stacked in sequence, and the first metal contact layer 31 is formed on the metal connection layer 23.

[0023] The metal protective layer 60 is electrically connected to the welding electrode 50, and the metal protective layer 60 covers and protects the grain side edge 302 and the carrier plate side edge 201 through the sidewall insulating layer 40. To clearly show the metal protective layer 60, only a portion of the metal protective layer 60 is drawn with cross-sectional lines. In actual implementation, the material of the sidewall insulating layer 40 is selected from the group consisting of SiO2, SiN, SiN / SiO2 / SiN, TiO2, and TiO2 / SiO2 / TiO2, while the material of the metal protective layer 60 is selected from the group consisting of Pt, TiW, Cr, Pt, Au, CuW, Cr / Au, Al / Cr / Au, Ti / Au, Ge / Ni / Au, Be / Au, and Ni / Au. Preferably, the thickness of the metal protective layer 60 is between 0.05 micrometers (µm) and 3 micrometers (µm). More preferably, the thickness of the metal protective layer 60 is 1.5 micrometers (µm).

[0024] Please refer to "" Figure 2 The diagram shown is a cross-sectional view of the subsequent process structure according to the first embodiment of the present invention. The conductive carrier plate 20 is formed on a substrate 70, which has a first electrode pad 71 and a second electrode pad 72. The second electrode pad 72 is electrically connected to the conductive carrier plate 20, and the first electrode pad 71 is electrically connected to the welding electrode 50. In practice, the first electrode pad 71 is electrically connected to the welding electrode 50 via a metal connecting block 73. The metal connecting block 73 includes a horizontal portion 731 and a vertical portion 732. The horizontal portion 731 is electrically connected to the welding electrode 50, and the vertical portion 732 is electrically connected to the first electrode pad 71. A filler portion 80 may be provided between the vertical portion 732 and the metal protective layer 60.

[0025] like" Figure 2 In the embodiment shown, the metal connector 73 can be manufactured using electroplating or chemical plating processes, which can replace the traditional wire bonding process and is more suitable for mass production. During the electroplating or chemical plating process, regardless of whether the sidewall insulation layer 40 has defects (cracks), the metal protective layer 60 can effectively block moisture and conductive substances (metal ions). Furthermore, before the electroplating or chemical plating process, the metal protective layer 60 can be used as a test contact to detect the forward bias voltage (Vf), reverse leakage current (Ir), and other circuit characteristics of the light-emitting diode element 10. The quality of the sidewall insulation layer 40 can be evaluated by the measured values, thereby eliminating defective products and improving the yield of subsequent processes.

[0026] Please see " Figure 3 The diagram shown is a cross-sectional view of the structure according to a second embodiment of the present invention. The sidewall insulating layer 40 covers the upper edge 202 of the carrier plate, while the metal protective layer 60 covers the upper edge 202 of the carrier plate through the sidewall insulating layer 40. In one embodiment, the width of the upper edge 202 of the carrier plate is between 10 micrometers (µm) and 50 micrometers (µm), and the width of the outer side of the upper edge 202 of the carrier plate without the metal protective layer 60 is at least 5 micrometers (µm).

[0027] like" Figure 1 "and" Figure 3 In the first and second embodiments shown, the conductive carrier plate 20 and the light-emitting diode chip 30 can be rectangular, so that the chip side edge 302 and the carrier side edge 201 respectively have four chip side surfaces 303 and four carrier side surfaces 203. The metal protective layer 60 covers and protects the four chip side surfaces 303 and the four carrier side surfaces 203, thereby achieving a proper protective effect.

[0028] Please refer to "" Figure 4 As shown in the third embodiment of the present invention, in order to reduce manufacturing costs, the metal protective layer 60 may only cover and protect the grain side surface 303 and the carrier plate side surface 203 closest to the welding electrode 50. This is because, in the electroplating or chemical plating process, the grain side surface 303 and the carrier plate side surface 203 closest to the welding electrode 50 are most likely to be exposed to moisture and conductive substances (metal ions). Therefore, the metal protective layer 60 can be applied to the grain side surface 303 and the carrier plate side surface 203 closest to the welding electrode 50 to save manufacturing costs.

[0029] As described above, the features of the present invention include at least:

[0030] 1. Through the coating of this metal protective layer, it can effectively block moisture and conductive substances (metal ions), thus strengthening and providing double protection for the sidewall insulation layer.

[0031] 2. The metal protective layer can be used as a test contact to detect the forward bias voltage (Vf), reverse leakage current (Ir), etc. of the light-emitting diode element, so as to evaluate the quality of the sidewall insulation layer through the measured values.

[0032] 3. The metal protective layer can be partially applied to the grain side surface and the carrier plate side surface closest to the welding electrode to save manufacturing costs.

Claims

1. A vertical light-emitting diode structure, characterized in that, Include: A light-emitting diode (LED) element includes a conductive substrate and an LED die formed on the conductive substrate. The LED die has an upper edge and a side edge connected to the upper edge and surrounding the LED die. The conductive substrate has a side edge connected to the side edge and an upper edge connected to the side edge and without the LED die above the upper edge of the substrate. A sidewall insulating layer covers the upper edge of the die, the side edge of the die, and the side edge of the carrier plate. The sidewall insulating layer has a first electrode exposed area at the upper edge of the die, and the first electrode exposed area exposes the light-emitting diode die. A welding electrode that passes through the exposed area of ​​the first electrode and is electrically connected to the light-emitting diode chip; and A metal protective layer is electrically connected to the welding electrode, and the metal protective layer covers and protects the edge of the die and the edge of the carrier plate through the sidewall insulating layer. The conductive carrier plate and the light-emitting diode die are rectangular, so that the edge of the die and the edge of the carrier plate have four edge faces and four edge faces respectively, and the metal protective layer covers and protects the four edge faces of the die and the four edge faces of the carrier plate.

2. The vertical light-emitting diode structure according to claim 1, characterized in that, The light-emitting diode chip includes a first metal contact layer, a first electrical semiconductor layer, an active layer and a second electrical semiconductor layer stacked in sequence, wherein the welding electrode is electrically connected to the second electrical semiconductor layer.

3. The vertical light-emitting diode structure according to claim 2, characterized in that, The conductive substrate includes a metal electrode, a conductive block and a metal connection layer stacked in sequence, and the first metal contact layer is formed on the metal connection layer.

4. The vertical light-emitting diode structure according to claim 1, characterized in that, The sidewall insulation layer covers the upper edge of the carrier plate, while the metal protective layer covers the upper edge of the carrier plate through the sidewall insulation layer.

5. The vertical light-emitting diode structure according to claim 4, characterized in that, The width of the upper edge of the substrate is between 10 micrometers and 50 micrometers, while the width of the outer side of the upper edge of the substrate without the metal protective layer is at least 5 micrometers.

6. The vertical light-emitting diode structure according to claim 1, characterized in that, The material of the sidewall insulating layer is selected from the group consisting of SiO2, SiN, SiN / SiO2 / SiN, TiO2 and TiO2 / SiO2 / TiO2, while the material of the metal protective layer is selected from the group consisting of Pt, TiW, Cr, Pt, Au, CuW, Cr / Au, Al / Cr / Au, Ti / Au, Ge / Ni / Au, Be / Au and Ni / Au.

7. The vertical light-emitting diode structure according to claim 1, characterized in that, The thickness of the metal protective layer is between 0.05 micrometers and 3 micrometers.

8. The vertical light-emitting diode structure according to claim 7, characterized in that, The thickness of the metal protective layer is 1.5 micrometers.

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