METHOD OF MAKING LIGHT EMITTING DEVICE AND LIGHT EMITTING DEVICE MADE THEREOF
This disclosure discloses a method of making a light-emitting device. The method comprises forming a plurality of light-emitting chips, each of the light-emitting chips comprising an epitaxial structure and an electrode formed on the epitaxial structure; forming a protection layer on the electrode in each of the light-emitting chips; forming a plurality of light-emitting groups by collecting the light-emitting chips, wherein each of the light-emitting groups having substantially the same opto-electrical characteristics; forming a wavelength converted layer in each of the light-emitting groups to cover the epitaxial structure and the protection layer; and removing the wavelength converted layer on the protection layer to expose the protection layer.
Latest Epistar Corporation Patents:
1. Technical Field
The present disclosure relates to a method of making a light-emitting device, and in particular to a method comprising forming a protection layer on each of light-emitting units on a single wafer.
2. Description of the Related Art
The light-emitting diodes (LEDs) of the solid-state lighting elements have the characteristics of low power consumption, low heat generation, long operational life, shockproof, small volume, quick response and good opto-electrical property like light emission with a stable wavelength, so the LEDs have been widely used in household appliances, indicator light of instruments, and opto-electrical products, etc.
A phosphor material is widely used on blue LEDs to generate a white light LED. When manufacturing the white light LED, since blue LEDs have different emission wavelengths and optical powers, it is difficult to obtain a desired CIE coordinate for each blue LEDs on a single wafer.
In addition, the white light LED can be further connected to other components in order to form a light emitting apparatus. The white light LED may be mounted onto a submount with the side of the substrate, or a solder bump or a glue material may be formed between the submount and the white light LED, therefore a light-emitting apparatus is formed. Besides, the submount further comprises the circuit layout electrically connected to the electrode of the white light LED.
SUMMARY OF THE DISCLOSUREThe present disclosure provides a method of making a light-emitting device and a light-emitting device made thereof.
The method of making a light-emitting device comprises: forming a plurality of light-emitting chips, wherein each of the light-emitting chips comprising an epitaxial structure and an electrode formed on the epitaxial structure; forming a protection layer on the electrode in each of the light-emitting chips; forming a plurality of light-emitting groups by collecting the light-emitting chips, wherein each of the light-emitting groups having substantially the same opto-electrical characteristics; forming a wavelength converted layer in each of the light-emitting groups to cover the epitaxial structure and the protection layer; and removing the wavelength converted layer on the protection layer to expose the protection layer.
The present disclosure also provides a light-emitting device.
The light-emitting device comprises: a substrate; a substrate; a light-emitting stack formed on the substrate and having a top region; a wavelength converted layer formed on the light-emitting stack and has a first portion covering on the top region of the light-emitting stack and a second portion protruding from the first portion with a first distance.
The present disclosure also provides a light-emitting device.
The light-emitting device comprises: a substrate having a top surface, a bottom surface, and four side regions between the top and bottom surfaces; a light-emitting stack on the top surface of the substrate and having a top region; a metal bump electrically couple to the light-emitting stack; and a wavelength converted layer formed on the four side regions and the top region of the light-emitting stack without covering the metal bump.
The accompanying drawing is included to provide easy understanding of the application, and is incorporated herein and constitutes a part of this specification. The drawing illustrates the embodiment of the application and, together with the description, serves to illustrate the principles of the application.
The following shows the description of embodiments of the present disclosure in accordance with the drawing.
Referring to
Referring to
Generally, in this embodiment, the light generated by the light-emitting chip is mixed with the converted light converted by the wavelength converted layer to generate a white light having a CIE coordinate within the seven color temperature regions. It is noted that, since each of the light-emitting groups has different emission wavelength, the light-emitting groups are required to be covered by different wavelength converted layers emitting different light that each light can be defined by a CIE coordinate, thereby obtaining white light within one color temperature region. To be more specific, the light converted by different wavelength converted layers can have different main emission peak wavelength while having the same CIE coordinate. For example, when a first light-emitting group comprises the light-emitting chips having a main emission wavelength of about 450 nm, and a second light-emitting group comprises the light-emitting chips having a main emission wavelength of about 460 nm, a first wavelength converted layer emitting a light that has a first CIE coordinate (x=0.426, y=0.548) is adopted in the first light-emitting group to generate a first white light, and a second wavelength converted layer emitting a light that has a second CIE coordinate (x=0.444, y=0.536) is adopted in the second light-emitting group to generated a second white light. The first and the second white light have a CIE coordinate in the same color temperature region (for example, the region having a center point of 6500k). In this embodiment, the first wavelength converted layer with the first CIE coordinate has a main emission peak wavelength of 551 nm, and the second wavelength converted layer with the second CIE coordinate has a main emission peak wavelength of 558 nm. Alternatively, the first wavelength converted layer having a main emission peak wavelength of 554 nm can emit a light having the first CIE coordinate (x=0.426, y=0.548), and the second wavelength converted layer having a main emission peak wavelength of 560 nm can emit a light having the second CIE coordinate (x=0.444, y=0.536). In this embodiment, a thickness of the wavelength converted layer on the first light-emitting group is substantially the same as that on the second light-emitting group.
Furthermore, as shown in
Referring to
The light-emitting device can be composed of several materials such as the series of aluminum gallium indium phosphide (AlGaInP), the series of aluminum gallium indium nitride (AlGaInN), and/or the series of zinc oxide (ZnO). The active layer can be configured to be a single heterostructure (SH), a double heterostructure (DH), a double-side double heterostructure (DDH), or a multi-quantum well (MWQ) structure. Besides, the wavelength of the emitted light could be controlled by changing the number of the pairs of the quantum well.
The material of the substrate(s) used for growing or supporting the light-emitting structure unit(s) can include but does not limit to germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), sapphire, silicon carbide (SiC), silicon (Si), lithium aluminium oxide (LiAlO2), zinc oxide (ZnO), gallium nitride (GaN), aluminum nitride (AlN), glass, composite, diamond, CVD diamond, diamond-like carbon (DLC) and any combination thereof. The wavelength converted layer is phosphor, for example, Y3Al5O12. Besides, the wavelength converted layer can also be Gd3Ga5O12:Ce, (Lu,Y)3Al5O12:Ce, SrS:Eu, SrGa2S4:Eu, (Sr,Ca,Ba)(Al,Ga)2S4:Eu, (Ca,Sr)S:Eu,Mn, (Ca,Sr)S:Ce, (Sr,Ba,Ca)2Si5N8:Eu, (Ba,Sr,Ca)2SiO4:Eu, (Ca,Sr,Ba)Si2O2N2:Eu, and CdZnSe.
The foregoing description has been directed to the specific embodiments of this invention. It will be apparent to those having ordinary skill in the art that other alternatives and modifications can be made to the devices in accordance with the present disclosure without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the present disclosure covers modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.
Claims
1.-11. (canceled)
12. A light-emitting device comprising:
- a substrate;
- a light-emitting stack formed on the substrate and having a top region;
- a wavelength converted layer formed on the light-emitting stack and has a first portion covering the top region of the light-emitting stack and a second portion protruding from the first portion with a first distance.
13. The light-emitting device of claim 12, wherein the first distance ranges from 10 μm to 70 μm.
14. The light-emitting device of claim 12, wherein the second portion has a width less than that of the first portion.
15. The light-emitting device of claim 12, wherein each of the substrate and the light-emitting stack has a side region, and the wavelength converted layer covering and the side region of the substrate and the light-emitting stack.
16. The light-emitting device of claim 15, wherein the wavelength converted layer on the side region has a width smaller than a thickness of the wavelength converted layer on the top region.
17. The light-emitting device of claim 13, wherein the wavelength converted layer covering the top region of the light-emitting stack is spaced apart from the electrode with a second distance ranging from 1 to 10 μm.
18. The light-emitting device of claim 13, further comprising an electrode and a metal bump, wherein the metal bump is formed on a top surface of the electrode and has a sidewall and a top surface, and wherein the wavelength converted layer surrounds the sidewall without covering the top surface.
19. The light-emitting device of claim 18, further comprising a wire electrically connecting with the metal bump, and wherein the wavelength converted layer does not cover the wire.
20. A light-emitting device comprising:
- a substrate having a top surface, a bottom surface, and four side regions between the top and bottom surfaces;
- a light-emitting stack on the top surface of the substrate and having a top region;
- a metal bump electrically coupled to the light-emitting stack; and
- a wavelength converted layer formed on the four side regions and the top region of the light-emitting stack without covering the metal bump.
21. A method of making a light-emitting diode, comprising:
- preparing a plurality of light-emitting chips, one of the plurality of light-emitting chips comprising an electrode and a protection layer covering the electrode;
- forming a wavelength conversion layer on the protection layer after covering the electrode; and
- exposing the electrode after forming the wavelength conversion layer.
22. The method of claim 21, wherein the plurality of light-emitting chips have an emission wavelength difference smaller than 10 nm.
23. The method of claim 21, wherein the plurality of light-emitting chips have a forward voltage difference less than 0.4V.
24. The method of claim 21, wherein the preparing step comprises separating a plurality of light-emitting units after the protection layer is formed on the electrode.
25. The method of claim 24, wherein the plurality of light-emitting units are commonly formed on a wafer.
26. The method of claim 24, wherein the plurality of light-emitting units comprises a first light-emitting unit formed on a first wafer, and a second light-emitting unit formed on a second wafer.
27. The method of claim 21, wherein the exposing step comprises partially removing the wavelength conversion layer.
28. The method of claim 21, wherein the exposing step comprises substantially removing the protection layer.
29. The method of claim 21, wherein the exposing step comprises exposing the protection layer.
30. The method of claim 21, further comprising a step of removing a part of the protection layer before forming the wavelength conversion layer.
31. The method of claim 21, wherein the electrode is surrounded by the wavelength conversion layer.
32. The method of claim 21, wherein the electrode has a top surface which is entirely exposed at the exposing step.
33. The method of claim 21, wherein the one of the plurality of light-emitting chips further comprises an epitaxial structure which is not covered by the protection layer before forming the wavelength conversion layer.
34. A method of making a light-emitting diode, comprising:
- preparing a plurality of light-emitting units which are connected with each other, one of the plurality of light-emitting units comprising an epitaxial structure and an electrode;
- forming a protection layer on the electrode;
- disconnecting the plurality of light-emitting units from each other; and
- removing the protection layer to substantially expose the electrode.
35. The method of claim 34, further comprising a step of forming a wavelength conversion layer on the protection layer.
36. The method of claim 34, wherein the electrode has a top surface which is entirely exposed after the removing step.
37. The method of claim 34, wherein the removing step comprises using a solvent of N-methyl-2-pyrrolidone.
38. The method of claim 34, wherein the removing step is conducted after the disconnecting step.
39. The method of claim 34, wherein the epitaxial structure is substantially not covered by the protection layer.
40. The method of claim 34, further comprising a step of grouping a part of the plurality of light-emitting units into a light-emitting group before the removing step.
Type: Application
Filed: Aug 9, 2012
Publication Date: Feb 13, 2014
Applicant: Epistar Corporation (Hsinchu)
Inventors: Ming-Chi Hsu (Hsinchu), Chih-Ming Wang (Hsinchu), Chien-Yuan Wang (Hsinchu)
Application Number: 13/570,558
International Classification: H01L 33/50 (20100101); H01L 33/08 (20100101);