[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.
[0033] See figure 2 The present invention provides a flip-chip LED chip for backlight display, which includes a substrate 10, a light-emitting structure, a first reflective layer 30 and a scattering layer 40.
[0034] The front surface of the substrate 10 includes a light-emitting area and a reflection area, the reflection area is located around the light-emitting area, the back of the substrate 10 is provided with a scattering area and a light-emitting area, and the reflection area is located around the light-emitting area. The light emitting area is located around the scattering area, and the scattering area is located above the light emitting area.
[0035] The light emitting structure of the present invention is arranged in the light emitting area, and the first reflective layer 30 is arranged in the reflecting area. Specifically, the light-emitting structure includes a first semiconductor layer 21, an active layer 22, a second semiconductor layer 23, a transparent conductive layer 24, and a second reflective layer 25 sequentially disposed on the substrate 10. The second reflective layer 25 reflects the light emitted by the active layer 22 to one side of the substrate 10 and exits. The light-emitting structure further includes a first electrode 26 and a second electrode 27. The first electrode 26 is electrically connected to the first semiconductor layer 21, so The second electrode 27 is electrically connected to the second semiconductor layer 23.
[0036] The chip of the present invention further includes an insulating layer 50 disposed on the surface of the light emitting structure and extending to the first reflective layer 30. The insulating layer 50 is made of SiO 2 , Si 3 N 4 , Al 2 O 3 , TiO 2 And Ta 2 O 3 Made of one or more of the materials.
[0037] The first reflective layer 30 of the present invention is made of SiO 2 , Si 3 N 4 , Al 2 O 3 , TiO 2 And Ta 2 O 3 Made of two or more of the materials. The second reflective layer 25 is made of SiO 2 , Si 3 N 4 , Al 2 O 3 , TiO 2 And Ta 2 O 3 Made of two or more of the materials. The second reflective layer may also be a metal reflective layer.
[0038] The scattering layer 40 of the present invention is arranged on the scattering area, which is located above the light emitting area. The light emitted from the light emitting structure to the side of the substrate 10 is scattered and reflected by the scattering layer 40, and the light reflected by the scattering layer 40 is first The reflective layer 30 reflects to the back surface of the substrate 10 and emits light to increase the light exit angle of the chip.
[0039] The scattering layer 40 of the present invention includes SiO 2 Layer 41 and Al layer 42, the SiO 2 The layer 41 is provided between the substrate 10 and the Al layer 42. SiO of the present invention 2 The layer 41 serves as an intermediate adhesion layer so that the Al layer 42 is fixed on the back of the substrate 10. If the Al layer 42 is directly vapor-deposited on the back surface of the substrate 10, the Al layer 42 will easily fall off. The Al layer 42 of the present invention is used to reflect light above the light emitting structure.
[0040] The existing DBR reflective layer is generally SiO 2 /Ti 2 O 5 Double composite layer, where SiO 2 As a constructive reflection (its own refractive index is 1.46 lower), Ti 2 O 5 As a destructive reflection (its own refractive index is about 2.5), it can be used as a reflective layer by adjusting the thickness of the two layers with optical simulation. However, the conventional DBR reflective layer is difficult to process in a certain area like the scattering layer 40 of the present invention.
[0041] The scattering layer 40 of the present invention first uses a DBR vapor deposition machine to vaporize a layer of SiO on the back of the substrate 10 2 Layer 41, and then using a metal evaporation machine, in SiO 2 An Al layer 42 is evaporated on the layer 41.
[0042] It should be noted that the SiO of the present invention 2 The thickness of the layer 41 and the Al layer 42 play an important role in the performance of the scattering layer 40. Preferably, the SiO 2 The thickness of the layer 41 is 30-200 nm, and the thickness of the Al layer 42 is 100-500 nm. If SiO 2 The thickness of the layer 41 is less than 30nm, the thickness is too thin, and it is difficult to adhere the Al layer 42 on the substrate 10; if the SiO 2 The thickness of the layer 41 is greater than 200 nm, if the thickness is too thick, it will absorb light and reduce the light output efficiency of the chip. If the thickness of the Al layer 42 is less than 100 nm, the thickness is too thin and affects the reflectivity of the scattering layer 40; if the thickness is greater than 500 nm, the thickness is too thick, which not only increases the volume of the chip, but also wastes cost.
[0043] See image 3 The light emitted by the active layer 22 passes through the substrate 10 and exits from the back of the substrate 10, and the scattering layer 40 provided on the back of the substrate 10 reflects the light above the light emitting structure to the first reflective layer 30. A reflective layer 30 reflects the light to the light exit area, thereby increasing the light exit angle of the chip.
[0044] In the present invention, the scattering layer 40 and the first reflective layer 30 cooperate with each other to prevent the light emitted by the light-emitting structure from directly emitting from the substrate 10, but to increase the chip size by the principle of reflection between the scattering layer 40 and the first reflective layer 30 The angle of light.
[0045] Preferably, the scattering area is located directly above the light-emitting area, that is, the scattering layer 40 is located directly above the light-emitting structure.
[0046] The contact area between the scattering layer 40 and the substrate 10 of the present invention is a, and the contact area between the light-emitting structure and the substrate 10 is b, a=(0.8-1.1)*b. Only when the ratio of a to b is in the above range can the light-emitting angle and light-emitting area be increased while preventing light from being absorbed by the quantum well due to bounce back and forth, thereby ensuring the light-emitting efficiency of the chip. Preferably, a=b.
[0047] Preferably, the light-emitting structure is located on the geometric center of the front surface of the substrate 10. It should be noted that the difference between the thickness of the substrate 10 and the area of the substrate 10 and the light-emitting structure has an important influence on the light-emitting efficiency of the chip.
[0048] See Figure 4 , The distance between the light-emitting structure and the edge of the substrate 10 is d, the thickness of the substrate 10 is h, d=(0.7-1.2)*h.
[0049] Since the light emitted by the light-emitting structure needs to be reflected by the substrate 10, in principle, the area of the substrate 10 is larger than the area of the light-emitting structure, the better, but when the area of the substrate 10 is larger than the area of the light-emitting structure by a certain range , That is, when d is greater than 1.2h, the light emitted from the edge of the substrate 10 is less. Since the flip-chip LED chip of the present invention is used for backlight display, if the area of the substrate 10 is too large, it will affect the use. In addition, if d is less than 0.7h, the light-emitting angle of the chip will be relatively reduced. Preferably, d=h.
[0050] Correspondingly, the present invention also provides a method for manufacturing a flip-chip LED chip for backlight display, including:
[0051] 1. Form a light-emitting structure on the light-emitting area on the front side of the substrate;
[0052] Specifically, MOCVD is used to sequentially form a first semiconductor layer, an active layer, and a second semiconductor layer on the front surface of the substrate to form an epitaxial layer. The epitaxial layer is etched to the surface of the substrate, the exposed area is the reflective layer, and the area of the remaining epitaxial layer is the light-emitting area, and the reflective area is located around the light-emitting area.
[0053] A transparent conductive layer, a second reflective layer, a first electrode and a second electrode are formed on the epitaxial layer.
[0054] 2. Form a first reflective layer on the reflective area on the front surface of the substrate;
[0055] A first reflective layer is formed on the exposed substrate, and the first reflective layer is made of SiO 2 , Si 3 N 4 , Al 2 O 3 , TiO 2 And Ta 2 O 3 Made of two or more of the materials.
[0056] In addition, in order to protect the light emitting structure, an insulating layer is formed on the surface of the light emitting structure and the first reflective layer. The insulating layer is made of SiO 2 , Si 3 N 4 , Al 2 O 3 , TiO 2 And Ta 2 O 3 Made of one or more of the materials.
[0057] 3. A scattering layer is formed on the scattering area on the back of the substrate, the scattering layer includes SiO 2 Layer and Al layer, the SiO 2 The layer is arranged between the substrate and the Al layer;
[0058] Specifically, a DBR evaporation machine is used to deposit a layer of SiO on the scattering area on the back of the substrate 2 Layer, and then using metal evaporation machine, in SiO 2 An Al layer is evaporated on the layer.
[0059] It should be noted that the SiO of the present invention 2 The thickness of the layer and the Al layer play an important role in the performance of the scattering layer. Preferably, the SiO 2 The thickness of the layer is 30-200 nm, and the thickness of the Al layer is 0-500 nm. If SiO 2 The thickness of the layer is less than 30nm, the thickness is too thin, it is difficult to adhere the Al layer on the substrate; if the SiO 2 The thickness of the layer is greater than 200 nm, if the thickness is too thick, it will absorb light and reduce the light extraction efficiency of the chip. If the thickness of the Al layer is less than 0 nm, the thickness is too thin, which affects the reflectivity of the scattering layer; if the thickness is greater than 500 nm, the thickness is too thick, which not only increases the volume of the chip, but also wastes cost.
[0060] In the present invention, the scattering layer and the first reflective layer 30 cooperate with each other to prevent the light emitted by the light emitting structure from directly emitting from the substrate, but to increase the light output angle of the chip by the principle of reflection between the scattering layer and the first reflective layer 30 .
[0061] Preferably, the scattering area is located directly above the light-emitting area, that is, the scattering layer is located directly above the light-emitting structure.
[0062] The contact area between the scattering layer and the substrate of the present invention is a, and the contact area between the light-emitting structure and the substrate is b, a=(0.8-1.1)*b. Only when the ratio of a to b is in the above range, can the light-emitting angle and light-emitting area be increased while preventing light from being absorbed by the quantum well due to bounce back and forth, thereby ensuring the light-emitting efficiency of the chip. Preferably, a=b.
[0063] Preferably, the light emitting structure is located on the geometric center of the front surface of the substrate. It should be noted that the difference between the thickness of the substrate and the area of the substrate and the light-emitting structure has an important influence on the light-emitting efficiency of the chip.
[0064] The distance between the light-emitting structure and the edge of the substrate is d, and the thickness of the substrate is h, d=(0.7-1.2)*h.
[0065] Since the light emitted by the light-emitting structure needs to be reflected by the substrate, in principle, the area of the substrate is larger than the area of the light-emitting structure, the better, but when the area of the substrate is larger than the area of the light-emitting structure by a certain range, that is, d When it is greater than 1.2h, the light emitted from the edge of the substrate is less. Since the flip-chip LED chip of the present invention is applied to a backlight display, if the area of the substrate is too large, the use will be affected. In addition, if d is less than 0.7h, the light-emitting angle of the chip will be relatively reduced. Preferably, d=h.
[0066] What is disclosed above is only a preferred embodiment of the present invention, which of course cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope of the present invention.
