As the sapphire substrate thermal conductivity is poor, affecting the LED luminous efficiency. In order to solve the problem of LED cooling, the future may be the main structure of the vertical structure of the LED, LED industry to promote the development of technology. On the vertical structure of LED technology believe that we have heard, the following only from the technical surface of the introduction, for reference.
We know that LED chips have two basic structures, the lateral structure (Lateral) and the vertical structure (Vertical). The two electrodes of the lateral structure LED chip are on the same side of the LED chip, and the current flows in the n- and p-type confinement layers in a transverse direction. The two electrodes of the LED chip of the vertical structure are used as the second electrode on both sides of the LED epitaxial layer, so that almost all of the current flows vertically through the LED epitaxial layer due to the patterned electrode and all of the p-type confinement layer, Of the current, can improve the plane structure of the current distribution problem, improve the luminous efficiency, but also can solve the P pole shading problem, enhance the LED light emitting area.
We first understand the vertical structure of the LED manufacturing technology and basic methods:
Manufacturing vertical structure LED chip technology has three main methods:
First, the use of silicon carbide substrate growth GaN film, the advantage is the same operating current conditions, light attenuation, long life, the lack of silicon substrate will absorb light.
Second, the use of chip bonding and stripping technology manufacturing. The advantage is light attenuation, long life, the lack of the need to deal with the LED surface to improve the luminous efficiency.
Three is the use of heterogeneous substrates such as silicon substrate growth gallium nitride LED epitaxial layer, the advantage is good heat dissipation, easy processing.
There are two basic ways to fabricate a vertical structure LED chip: peeling the grown substrate and not stripping the grown substrate. The vertical structure of the GaP-based LED chip grown on the gallium arsenide growth substrate has two structures:
Non-stripping conductive gallium arsenide growth substrate: depositing a conductive DBR reflective layer on a conductive gallium arsenide growth substrate, growing a GaP-based LED epitaxial layer on a conductive DBR reflective layer.
Stripping gallium arsenide growth substrate: laminated reflective layer on the GaP-based LED epitaxial layer, bonding conductive support substrate, stripping gallium arsenide substrate. The conductive support substrate includes a gallium arsenide substrate, a gallium phosphide substrate, a silicon substrate, a metal, an alloy, and the like.
In addition, the vertical GaN-based LEDs grown on silicon have two structures:
Does not peel off the silicon growth substrate: the metal reflective layer or the conductive DBR reflective layer is laminated on the conductive silicon growth substrate, and the gallium nitride-based LED epitaxial layer is grown on the metal reflective layer or the conductive DBR reflective layer.
Peel off the silicon growth substrate: Laminated metal reflective layer On the gallium nitride-based LED epitaxial layer, the conductive reflective substrate is bonded to the metal reflective layer to peel the silicon growth substrate.
And then a simple description of the manufacture of vertical gallium nitride-based LED process: laminated reflective layer in the gallium nitride-based LED epitaxial layer, in the reflective layer bonded conductive support substrate, stripping sapphire growth substrate. The conductive support substrate includes a metal and an alloy substrate, a silicon substrate, and the like.
Whether it is GaP-based LED, GaN-based LED, or ZnO-based LED vertical through this type of vertical structure of the LED, compared to the traditional structure of LED has a greater advantage, the specific performance:
1. The current, all the existing vertical structure of the color LED: red LED, green LED, blue LED and UV LED, can be made through the vertical structure of the hole LED has a great application market.
2.All the manufacturing process is in the chip (wafer) level.
3.Because there is no need to play gold line with the external power supply connected to the use of vertical through the vertical structure of the LED chip package thickness reduction. Therefore, it can be used to manufacture ultra-thin devices such as backlighting.
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