A high-brightness front-mounted LED chip and its manufacturing method

Abstract

The present invention discloses a high-brightness front-mounted LED chip and a manufacturing method thereof. The chip comprises a substrate, a plurality of light-emitting structures arranged on the front side of the substrate, and cutting grooves located between the light-emitting structures. The chip is characterized in that it also comprises a reflection and scattering layer with a patterned structure arranged on the back side of the substrate. The reflection and scattering layer is made of a white inorganic material or an inorganic fluorescent material. The reflection and scattering layer scatters and totally reflects the light emitted from the light-emitting structure to the back side of the substrate. The light reflected by the reflection and scattering layer becomes a full spectrum, so as to reduce the absorption of light by the light-emitting structure and improve the light output efficiency of the chip.

Description

Technical Field

[0001] The invention relates to the technical field of light emitting diodes, and in particular to a high-brightness front-mounted LED chip and a manufacturing method thereof. Background Art

[0002] The existing front-mounted LED chip includes a substrate, an epitaxial layer and an electrode arranged on the front side of the substrate. In order to improve the light extraction efficiency, technicians set a DBR layer or ODR layer on the back side of the substrate to reflect the light emitted from the epitaxial layer to the back side of the substrate to the front side of the substrate. However, the DBR layer or ODR layer has the following two disadvantages: 1. The reflection angle of light is small; 2. After the light is reflected, it will be absorbed by the epitaxial layer, forming secondary reflection. After repeated reflections, the light extraction efficiency will be reduced. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a high-brightness front-mounted LED chip and a manufacturing method thereof, so as to reduce the absorption of reflected light by the active layer and improve the light extraction efficiency of the chip.

[0004] The technical problem that the present invention needs to solve is to provide a high-brightness front-mounted LED chip and a manufacturing method thereof, which is convenient for cutting into single LED chips.

[0005] In order to solve the above technical problems, the present invention provides a high-brightness front-mounted LED chip, including a substrate, a plurality of light-emitting structures arranged on the front side of the substrate, and cutting grooves located between the light-emitting structures, and also including a reflection and scattering layer with a patterned structure arranged on the back side of the substrate, the reflection and scattering layer is made of white inorganic material or inorganic fluorescent material, the reflection and scattering layer scatters and totally reflects the light emitted by the light-emitting structure to the back side of the substrate, and the light reflected by the reflection and scattering layer becomes a full spectrum to reduce the absorption of light by the light-emitting structure.

[0006] As an improvement of the above solution, the reflection and scattering layer is composed of a plurality of granular white balls, the white balls are made of white inorganic material, and the particle size of the white balls is 0.5 to 1.5 μm.

[0007] As an improvement of the above solution, the white inorganic material is zirconium oxide or titanium oxide.

[0008] As an improvement of the above solution, the inorganic fluorescent material is made of alkaline earth metal sulfide or alkaline earth metal aluminate.

[0009] As an improvement of the above solution, the alkaline earth metal sulfide is ZnS or CaS.

[0010] As an improvement of the above scheme, the alkaline earth metal aluminate is SrAl2O4, CaAl2O4 or BaAl2O4.

[0011] As an improvement of the above solution, the thickness of the reflection and scattering layer is 100 to 3000 μm.

[0012] As an improvement of the above solution, the patterned structure includes an isolation groove, which is etched along the surface of the reflection and scattering layer to the surface of the substrate, and the position of the isolation groove corresponds to the cutting groove.

[0013] As an improvement of the above solution, the isolation groove includes a first isolation groove and a second isolation groove, and a notch is provided at the intersection of the first isolation groove and the second isolation groove. The notch is provided at the corner of the reflection and scattering layer to increase the area of ​​the intersection of the first isolation groove and the second isolation groove.

[0014] Accordingly, the present invention also provides a method for manufacturing a high-brightness front-mounted LED chip, comprising the following steps:

[0015] forming a plurality of light emitting structures and cutting grooves on the front surface of the substrate, wherein the cutting grooves are located between the light emitting structures;

[0016] A reflective scattering layer with a patterned structure is formed on the back of the substrate by using photolithography and etching processes. The reflective scattering layer is made of white inorganic material or inorganic fluorescent material. The reflective scattering layer scatters and totally reflects the light emitted by the light-emitting structure to the back of the substrate. The light reflected by the reflective scattering layer becomes a full spectrum to reduce the absorption of light by the light-emitting structure.

[0017] The implementation of the present invention has the following beneficial effects:

[0018] The present invention uses white inorganic materials to make granular white balls to form a reflection and scattering layer. The reflection and scattering layer of the present invention can not only scatter and reflect the light emitted from the active layer to the substrate side, but also reflect the light from the back of the substrate to the front of the substrate for emission, thus playing the role of the existing structure DBR layer or ODR layer. The more important role of the reflection and scattering layer of the present invention is that it can also convert the light emitted by the active layer into a full spectrum. The light reflected or scattered from the reflection and scattering layer to the front of the substrate will not be absorbed by the active layer because it is converted into a full spectrum, thereby improving the light extraction efficiency of the chip.

[0019] The present invention adopts an inorganic fluorescent material to form a reflection and scattering layer. The reflection and scattering layer of the present invention can not only scatter and reflect the light emitted from the active layer to the substrate side, but also reflect the light from the back of the substrate to the front of the substrate for emission, thus playing the role of the existing structure DBR layer or ODR layer. The more important role of the reflection and scattering layer of the present invention is that it can also convert the light emitted by the active layer into a full spectrum. The light reflected or scattered from the reflection and scattering layer to the front of the substrate will not be absorbed by the active layer because it is converted into a full spectrum, thereby improving the light extraction efficiency of the chip.

[0020] Since the present invention forms a reflection and scattering layer on the back side of the substrate and the material of the reflection and scattering layer is special, the reflection and scattering layer of the present invention needs to have a graphic structure, which is convenient for subsequent cutting to form a single LED chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of an LED chip embodiment 1 of the present invention;

[0022] Figure 2 Schematic diagram of light emission of LED chip embodiment 1 of the present invention;

[0023] Figure 3 is a schematic structural diagram of an LED chip embodiment 2 of the present invention;

[0024] Figure 4 is a top view of a first solution of a reflective scattering layer of an LED chip of the present invention;

[0025] Figure 5 is a top view of a second solution of the reflective scattering layer of the LED chip of the present invention;

[0026] Figure 6 It is a top view of the third solution of the reflection and scattering layer of the LED chip of the present invention. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0028] Example 1

[0029] See also Figure 1 The present invention provides a high-brightness front-mounted LED chip, including a substrate 10, a plurality of light-emitting structures 20 arranged on the front side of the substrate 10, and a cutting groove 30 located between the light-emitting structures 20. The present invention also includes a reflective scattering layer 40 with a patterned structure arranged on the back side of the substrate 10.

[0030] The light emitting structure 20 of the present invention comprises a first semiconductor layer 21 disposed on a substrate 10, an active layer 22 and a first electrode 24 disposed on the first semiconductor layer 21, and a second semiconductor layer 23 and a second electrode 25 disposed on the active layer 22. The substrate of the present invention is preferably a sapphire substrate, and the first semiconductor layer, the active layer and the second semiconductor layer are mainly made of gallium nitride material.

[0031] The reflection and scattering layer 40 is composed of a plurality of granular white balls made of white inorganic material. The reflection and scattering layer 40 scatters and totally reflects the light emitted from the active layer 22 to the back side of the substrate 10. The light reflected by the reflection and scattering layer 40 becomes a full spectrum to reduce the absorption of light by the active layer 22.

[0032] See also Figure 2 The present invention uses white inorganic materials to make granular white balls to form a reflection and scattering layer. The reflection and scattering layer of the present invention can not only scatter and reflect the light emitted from the active layer to the substrate side, but also reflect the light from the back of the substrate to the front of the substrate for emission, playing the role of the existing structure DBR layer or ODR layer. The more important role of the reflection and scattering layer of the present invention is that it can also convert the light emitted by the active layer into a full spectrum. The light reflected or scattered from the reflection and scattering layer to the front of the substrate will not be absorbed by the active layer because it becomes a full spectrum, thereby improving the light extraction efficiency of the chip.

[0033] It should be noted that the particle size of the white balls in the reflection and scattering layer plays an important role in the light extraction efficiency of the chip. Preferably, the particle size of the white balls is 1 to 10 μm. The size of an atom is about 0.3 μm. When the particle size of the white balls is greater than 3 atoms, a good scattering effect can be formed; in addition, if the particle size of the white balls is greater than 10 μm, the pores of the reflection and scattering layer are too large, and most of them are colloids, which reduces the brightness of the chip.

[0034] Preferably, the white inorganic material is zirconium oxide or titanium oxide.

[0035] It should be noted that the thickness of the reflective scattering layer of the present invention also has an important influence on the light extraction efficiency of the chip. Preferably, the thickness of the reflective scattering layer is 100 to 3000 μm. If the thickness of the reflective scattering layer is less than 100 μm, the thickness is too thin, and the light emitted by the active layer directly passes through the reflective scattering layer and light leakage occurs; if the thickness of the reflective scattering layer is greater than 3000 μm, the thickness is too thick, which increases the cost and is not easy to cut later.

[0036] More preferably, the thickness of the reflection and scattering layer is 300-800 μm.

[0037] Since the present invention forms a reflection and scattering layer on the back of the substrate, and the material of the reflection and scattering layer is special, the reflection and scattering layer of the present invention needs to have a graphic structure, so that it is convenient to cut and form a single LED chip later. The graphic structure of the reflection and scattering layer of the present invention includes an isolation groove 50, which is etched along the surface of the reflection and scattering layer 40 to the surface of the substrate 10, and the isolation groove 50 corresponds to the position of the cutting groove 30.

[0038] See also Figures 4 to 6 The isolation groove includes a first isolation groove 51 and a second isolation groove 52. A notch 53 is provided at the intersection of the first isolation groove 51 and the second isolation groove 52. The notch 53 is provided at the corner of the reflection and scattering layer 40 to increase the area of ​​the intersection of the first isolation groove 51 and the second isolation groove 52.

[0039] Example 2

[0040] See also Figure 3 The present invention provides a high-brightness front-mounted LED chip, including a substrate 10, a plurality of light-emitting structures 20 arranged on the front side of the substrate 10, and a cutting groove 30 located between the light-emitting structures 20. The present invention also includes a reflective scattering layer 40 with a patterned structure arranged on the back side of the substrate 10.

[0041] The light emitting structure 20 of the present invention comprises a first semiconductor layer 21 disposed on a substrate 10, an active layer 22 disposed on the first semiconductor layer 21, and a second semiconductor layer 23 disposed on the active layer 22. The substrate of the present invention is preferably a sapphire substrate, and the first semiconductor layer, the active layer and the second semiconductor layer are mainly made of gallium nitride material.

[0042] The reflective scattering layer 40 is made of inorganic fluorescent material, and scatters and totally reflects the light emitted from the active layer 22 to the back of the substrate 10 . The light reflected by the reflective scattering layer 40 becomes a full spectrum to reduce the absorption of light by the active layer 22 .

[0043] It should be noted that the present invention uses an inorganic fluorescent material to form a reflective scattering layer. The reflective scattering layer of the present invention can not only scatter and reflect the light emitted from the active layer to the substrate side, but also reflect the light from the back of the substrate to the front of the substrate for emission, thus playing the role of the existing structure DBR layer or ODR layer. The more important role of the reflective scattering layer of the present invention is that it can also convert the light emitted by the active layer into a full spectrum. The light reflected or scattered from the reflective scattering layer to the front of the substrate will not be absorbed by the active layer because it becomes a full spectrum, thereby improving the light extraction efficiency of the chip.

[0044] Specifically, the blue light emitted by the active layer is converted into white light after passing through the inorganic fluorescent material. Since the energy level of blue light is higher than that of white light, the white light reflected or scattered from the reflective scattering layer to the front of the substrate will not be absorbed by the active layer, thereby improving the light extraction efficiency of the chip.

[0045] Preferably, the inorganic fluorescent material is made of alkaline earth metal sulfide or alkaline earth metal aluminate.

[0046] More preferably, the alkaline earth metal sulfide is ZnS or CaS; the alkaline earth metal aluminate is SrAl2O4, CaAl2O4 or BaAl2O4.

[0047] It should be noted that the thickness of the reflective scattering layer of the present invention also has an important influence on the light extraction efficiency of the chip. Preferably, the thickness of the reflective scattering layer is 100 to 3000 μm. If the thickness of the reflective scattering layer is less than 100 μm, the thickness is too thin, and the light emitted by the active layer directly passes through the reflective scattering layer and light leakage occurs; if the thickness of the reflective scattering layer is greater than 3000 μm, the thickness is too thick, which increases the cost and is not easy to cut later.

[0048] More preferably, the thickness of the reflection and scattering layer is 300-800 μm.

[0049] Since the present invention forms a reflection and scattering layer on the back of the substrate, and the material of the reflection and scattering layer is special, the reflection and scattering layer of the present invention needs to have a graphic structure, so that it is convenient to cut and form a single LED chip later. The graphic structure of the reflection and scattering layer of the present invention includes an isolation groove 50, which is etched along the surface of the reflection and scattering layer 40 to the surface of the substrate 10, and the isolation groove 50 corresponds to the position of the cutting groove 30.

[0050] See also Figures 4 to 6 The isolation groove includes a first isolation groove 51 and a second isolation groove 52. A notch 53 is provided at the intersection of the first isolation groove 51 and the second isolation groove 52. The notch 53 is provided at the corner of the reflection and scattering layer 40 to increase the area of ​​the intersection of the first isolation groove 51 and the second isolation groove 52.

[0051] Accordingly, the present invention also provides a method for manufacturing a high-brightness front-mounted LED chip, comprising the following steps:

[0052] forming a plurality of light emitting structures and cutting grooves on the front surface of the substrate, wherein the cutting grooves are located between the light emitting structures;

[0053] A reflective scattering layer with a patterned structure is formed on the back of the substrate by using photolithography and etching processes. The reflective scattering layer is made of white inorganic material or inorganic fluorescent material. The reflective scattering layer scatters and totally reflects the light emitted by the light-emitting structure to the back of the substrate. The light reflected by the reflective scattering layer becomes a full spectrum to reduce the absorption of light by the light-emitting structure.

[0054] Specifically, the method for manufacturing the reflective scattering layer having a patterned structure is as follows:

[0055] 1. Use yellow light process to form a photoresist with the required pattern on the back of the substrate, perform proximity exposure, development and hard baking on the photoresist to form a photolithography mask pattern layer;

[0056] Specifically, the thickness of the photoresist is 7.5-8.5 μm, the coating speed is 800-1200 rpm, the soft baking temperature is 90-130°C, the distance between the proximity exposure mask and the photoresist is 10-20 μm, and the exposure amount is 140-170 mJ / cm 2 ; The developing time is 130 to 180 seconds, the hard baking temperature is 120 to 150°C, and the hard baking time is 20 to 50 minutes.

[0057] 2. A reflective scattering layer is formed on the back side of the substrate by an evaporation method.

[0058] It should be noted that the notch is etched into the reflective scattering layer by inductively coupled plasma (ICP), the etching gas is CF4, the ratio of CF4 to O2 is (8-10):1, and the etching time is 4200-4800s.

[0059] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A high-brightness front-mounted LED chip, comprising a substrate, a plurality of light-emitting structures disposed on the front surface of the substrate, and cutting grooves located between the light-emitting structures, characterized in that: It also includes a reflective scattering layer with a patterned structure arranged on the back of the substrate, the reflective scattering layer is made of an inorganic fluorescent material, the reflective scattering layer scatters and totally reflects the light emitted by the light-emitting structure to the back of the substrate, and the light reflected by the reflective scattering layer becomes a full spectrum, so as to reduce the absorption of light by the light-emitting structure; the thickness of the reflective scattering layer is 100-3000 μm; The inorganic fluorescent material is made of alkaline earth metal sulfide or alkaline earth metal aluminate; The alkaline earth metal sulfide is ZnS or CaS; the alkaline earth metal aluminate is SrAl2O4, CaAl2O4 or BaAl2O4.

2. The high brightness front-mounted LED chip according to claim 1, characterized in that: The patterned structure includes an isolation groove, which is etched along the surface of the reflection and scattering layer to the surface of the substrate, and the isolation groove corresponds to the position of the cutting groove.

3. The high brightness front-mounted LED chip according to claim 2, characterized in that: The isolation groove comprises a first isolation groove and a second isolation groove. A notch is arranged at the intersection of the first isolation groove and the second isolation groove. The notch is arranged at the corner of the reflection and scattering layer to increase the area of ​​the intersection of the first isolation groove and the second isolation groove.

4. A method for manufacturing a high-brightness front-mounted LED chip, used for manufacturing the high-brightness front-mounted LED chip as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: forming a plurality of light emitting structures and cutting grooves on the front surface of the substrate, wherein the cutting grooves are located between the light emitting structures; A reflective scattering layer with a patterned structure is formed on the back of the substrate by using photolithography and etching processes. The reflective scattering layer is made of an inorganic fluorescent material. The reflective scattering layer scatters and totally reflects the light emitted by the light-emitting structure to the back of the substrate. The light reflected by the reflective scattering layer becomes a full spectrum to reduce the light absorption by the light-emitting structure.

Images