US-12622097-B2 - Micro light-emitting diode structure

US12622097B2US 12622097 B2US12622097 B2US 12622097B2US-12622097-B2

Abstract

The present invention provides a micro light-emitting diode structure, which comprises: a first light-emitting layer, a second light-emitting layer, a third light-emitting layer, a first dielectric layer, a second dielectric layer, and a third dielectric layer stacked on one another sequentially. The first light-emitting layer, the second light-emitting layer, and the third light-emitting layer are connected electrically by fan-out circuit layers, respectively. A first area of the first dielectric layer is greater than a second area of the second dielectric layer. The second area is greater than a third area of the third dielectric layer. A first refractive index of the first dielectric layer is smaller than a second refractive index of the second dielectric layer. The second refractive index is smaller than a third refractive index of the third dielectric layer. By using this structure, the light-emitting angle of a micro LED can be further shrunk.

Inventors

Jr-Hau He
Zhi-Ting YE
Chun-Wei Tsai
Yuk-Tong Cheng

Assignees

RAYLEIGH VISION LIMITED

Dates

Publication Date: 20260505
Application Date: 20230524

Claims (10)

1 . A micro light-emitting diode structure, comprising: a first light-emitting layer; a second light-emitting layer, disposed on said first light-emitting layer, a first fan-out circuit layer disposed below said second light-emitting layer and connected electrically to said first light-emitting layer and said second light-emitting layer; a third light-emitting layer, disposed on said second light-emitting layer, a second fan-out circuit layer disposed below said third light-emitting layer and connected electrically to said second light-emitting layer and said third light-emitting layer; a first dielectric layer, disposed on said third light-emitting layer; a second dielectric layer, disposed on said first dielectric layer; and a third dielectric layer, disposed on said second dielectric layer; wherein a first area of said first dielectric layer is greater than a second area of said second dielectric layer; said second area is greater than a third area of said third dielectric layer; a first refractive index of said first dielectric layer is smaller than a second refractive index of said second dielectric layer; and said second refractive index is smaller than a third refractive index of said third dielectric layer; wherein one of said first light-emitting layer, said second light-emitting layer, and said third light-emitting layer is configured to emit red light, one of said first light-emitting layer, said second light-emitting layer, and said third light-emitting layer is configured to emit green light, and one of said first light-emitting layer, said second light-emitting layer, and said third light-emitting layer is configured to emit blue light; wherein light emitted from said first light-emitting layer, said second light-emitting layer, and said third light-emitting layer is incident in said first dielectric layer and passes successively through said first dielectric layer, said second dielectric layer, and said third dielectric layer; and wherein said first dielectric layer, said second dielectric layer, and said third dielectric layer form a multilayer optical structure configured to progressively focus the incident light such that the incident light becomes more focused when passing from said first dielectric layer into said second dielectric layer and becomes further focused when passing from said second dielectric layer into said third dielectric layer.
2 . The micro light-emitting diode structure of claim 1 , further comprising a substrate, said first light-emitting layer disposed on said substrate, a third fan-out circuit layer disposed below said first light-emitting layer, and said third fan-out circuit layer connected electrically to said first light-emitting layer and said substrate.
3 . The micro light-emitting diode structure of claim 2 , wherein the material of said substrate is selected from the group consisting of gallium nitride, gallium arsenide, gallium phosphide, indium phosphide, silicon carbide, and aluminum oxide.
4 . The micro light-emitting diode structure of claim 1 , wherein said first dielectric layer is a grid index layer.
5 . The micro light-emitting diode structure of claim 1 , wherein said first dielectric layer, said second dielectric layer, and said third dielectric layer are formed by the reactive-ion etching (RIE).
6 . The micro light-emitting diode structure of claim 1 , wherein the material of said first light-emitting layer, said second light-emitting layer, and said third light-emitting layer is selected from the group consisting of gallium nitride, aluminum indium gallium phosphide, aluminum gallium arsenide, and aluminum gallium phosphide.
7 . The micro light-emitting diode structure of claim 1 , wherein said first light-emitting layer, said second light-emitting layer, and said third light-emitting layer include an n-type semiconductor and a p-type semiconductor, respectively.
8 . The micro light-emitting diode structure of claim 1 , wherein the energy bandgap of said first light-emitting layer is greater than the energy bandgap of said second light-emitting layer; the energy bandgap of said second light-emitting layer is greater than the energy bandgap of said third light-emitting layer.
9 . The micro light-emitting diode structure of claim 1 , wherein the energy bandgap of said first light-emitting layer is smaller than the energy bandgap of said second light-emitting layer; the energy bandgap of said second light-emitting layer is smaller than the energy bandgap of said third light-emitting layer.
10 . A micro light-emitting diode structure, comprising: a first light-emitting layer; a second light-emitting layer, disposed on said first light-emitting layer, a first fan-out circuit layer disposed below said second light-emitting layer and connected electrically to said first light-emitting layer and said second light-emitting layer; a third light-emitting layer, disposed on said second light-emitting layer, a second fan-out circuit layer disposed below said third light-emitting layer and connected electrically to said second light-emitting layer and said third light-emitting layer; a first dielectric layer, disposed on said third light-emitting layer; a second dielectric layer, disposed on said first dielectric layer; and a third dielectric layer, disposed on said second dielectric layer; wherein a first area of said first dielectric layer is smaller than a second area of said second dielectric layer; said second area is smaller than a third area of said third dielectric layer; a first refractive index of said first dielectric layer is greater than a second refractive index of said second dielectric layer; and said second refractive index is greater than a third refractive index of said third dielectric layer; wherein one of said first light-emitting layer, said second light-emitting layer, and said third light-emitting layer is configured to emit red light, one of said first light-emitting layer, said second light-emitting layer, and said third light-emitting layer is configured to emit green light, and one of said first light-emitting layer, said second light-emitting layer, and said third light-emitting layer is configured to emit blue light; wherein light emitted from said first light-emitting layer, said second light-emitting layer, and said third light-emitting layer is incident in said first dielectric layer and passes successively through said first dielectric layer, said second dielectric layer, and said third dielectric layer; and wherein said first dielectric layer, said second dielectric layer, and said third dielectric layer form a multilayer optical structure configured to progressively focus the incident light such that the incident light becomes more focused when passing from said first dielectric layer into said second dielectric layer and becomes further focused when passing from said second dielectric layer into said third dielectric layer.

Description

BACKGROUND OF THE INVENTION The micro light-emitting diode (micro LED) is a novel display technology formed by miniature light-emitting chips. In comparison to the LED or organic LED (OLED) display technology according to the prior art, micro LEDs own higher brightness, contrast, and color expressiveness as well as greater performance and longer lifetime. Compared with the display technologies according to the prior art, micro LEDs own many advantages including primarily the brightness and contrast. The brightness of a micro LED can reach ten times the brightness of a general OLED. The contrast of a micro LED is also higher. These advantages make micro LED displays are apparently superior in color reproduction and image quality. The advantage of micro LEDs is their color expressiveness. Since micro LED displays adopt pure light sources, they can display a broader color gamut and hence providing truer and more vivid colors. In addition, micro LED displays also provide local brightness adjustment. This means that they can adjust brightness in different regions of a display independently and thus achieving superior contrast and performance. The third advantage is greater performance and longer lifetime. In addition, micro LED use pure light sources. Thereby, no backlight and color filter layer is required, which enhances the light-emitting efficiency. Owing to the advantages of micro LEDs, they have become the primary choice for high-end display products, including smartphones, tablet computers, televisions, VR/AR helmets, and automotive displays. As consumers' requests for higher quality and resolution, the micro LED technology has attracted more attention. Compared to LCD displays, LED displays, and OLED displays, micro LED display have higher brightness and better contrast. Besides, they also have broader color gamut. Consequently, micro LED displays have been regarded as an important development direction for next-generation display technologies. Furthermore, the advantages of micro LEDs also include reliability and long-term costs. Thanks to their longer lifetime and durability, compared to other technologies, micro LEDs are more economical. In addition, due to their low power consumption and long lifetime, this technology can maintain high-quality displays for a long time without excessive maintenance or replacement of parts. Unfortunately, owing its miniature size, the micro LED according to the prior art cannot install a light-concentrating device on the light-emitting surface like the prior art, making micro LEDs difficult in shrinking the light-emitting angle and leading to inconsistent brightness. Moreover, when the dies of the micro LEDs according to the prior art emit light, the light-emitting angle is too wide, resulting in light mixing and inaccurate colors. Accordingly, it is urged to have a micro LED structure capable shrinking the light-emitting angle effectively. To solve the above problem according to the prior art, the present invention provides a micro LED structure, which uses a plurality of dielectric layers with gradually shrinking widths from the bottom up. By adopting a plurality of light-emitting layers with fan-out packaging, the light emitting by the plurality of light-emitting layers can be concentrated and thus shrinking the light-emitting angle of the micro LED structure. SUMMARY OF THE INVENTION An objective of the present invention is to provide a micro LED structure, which disposes a plurality of dielectric layer with gradually shrinking widths from the bottom up on a plurality of light-emitting layers with fan-out packaging so that the light emitted by the plurality of light-emitting layers can be concentrated an thus shrinking the light-emitting angle of the micro LED structure. To achieve the above objective and efficacy, the present invention provides a micro LED structure, which comprises: a first light-emitting layer, a second light-emitting layer, a third light-emitting layer, a first dielectric layer, a second dielectric layer, and a third dielectric layer. The second light-emitting layer is disposed on the first light-emitting layer. A first fan-out circuit layer is disposed below the second light-emitting layer and connected electrically to the first light-emitting layer and the second light-emitting layer. The third light-emitting layer is disposed on the second light-emitting layer. A second fan-out circuit layer is disposed below the third light-emitting layer and connected electrically to the second light-emitting layer and the third light-emitting layer. The first dielectric layer is disposed on the third light-emitting layer. The second dielectric layer is disposed on the first dielectric layer. The third dielectric layer is disposed on the second dielectric layer. A first area of the first dielectric layer is greater than a second area of the second dielectric layer. The second area is greater than a third area of the third dielectric layer. A first refracti