A kind of LED electrode structure and manufacturing method thereof

Abstract

The invention firstly aims to provide an LED electrode structure. A first Ni layer, an Al layer, a Cr layer, a second Ni layer and an Au layer are sequentially included from the surface layer of a GaN layer, and through holes are formed in the first Ni layer. The Al layer is designed to be closely next to the first Ni layer and can reflect the light transmitted to a P electrode and an N electrode to the inside of a chip, the reflected light is emitted out from the inside of the chip again, and therefore the external quantum efficiency of an LED chip is improved. Cr can achieve an adhesion effect and also can prevent Al metal atoms from diffusing towards the Ni layer and the Au layer above the electrodes, and the stability of the electrodes is improved. The design of the through holes can reduce the absorption to the light of the first Ni layer, the light-emitting efficiency is maximally improved, and the good contact of the Al layer and the surface of GaN can also be guaranteed. The invention secondarily aims to provide a manufacturing method of the LED electrode structure. The manufacturing method is simple, concise and suitable for mass production. The adhesivity between film layers is very good, and the stability of the entire electrode is good.

Description

technical field [0001] The invention relates to the field of optoelectronic devices, in particular to an LED electrode structure and a manufacturing method thereof. Background technique [0002] LED is a solid light source, which is a light-emitting device made of semiconductor P-N junction. During forward conduction, the minority carriers in the semiconductor recombine with the majority carriers, and the released energy is emitted in the form of photons or partly in the form of photons. Semiconductor LED lighting has significant advantages such as high efficiency, energy saving, environmental protection, long service life, etc., and has been widely used in various fields such as street lamps, display screens, indoor lighting, and automobile lights. How to improve luminous efficiency is the main problem that LED needs to solve. [0003] At present, the traditional P and N electrodes generally adopt Ni / Au structure or Cr / Pt / Au structure. These two metal electrode structures...

AI Technical Summary

Problems solved by technology

[0003] At present, the traditional P and N electrodes generally adopt Ni / Au structure or Cr / Pt / Au structure. These two metal electrode structures have better stability, but a large part of the light emitted from the light-emitting area inside the chip will be absorbed by the electrodes. , thereby reducing the luminous efficiency of the LED

There are also reflective layers that use metal Ag or Al as the electrode. Ag has high reflectivity and can be directly deposited on p-GaN to form a good ohmic contact, but its adhesion is poor, and the electrochemical properties of Ag are unstable. , sensitive to the preparation process, easy to oxidize in the air, and will condense when exposed to high temperature

Al can form a strong and stable ohmic contact on n-GaN, but Al cannot form a good ohmic contact on p-GaN

In order to solve the problem of ohmic contact and adhesion, a thin film is usually designed between Al and GaN, but the thin film will absorb light, thus affecting the luminous efficiency of LED

[0004] Patent Application No. 200410058035.7 "Al / Ti / Aluminum / Nickel / Gold Ohmic Contact System for Gallium Nitride Devices" discloses an Al / Ti / Al / Ni / Au electrode, in which the Al layer directly Contact with the GaN surface can guarantee the luminous efficiency of the LED, but there are two problems: one is that the adhesion between the entire electrode and GaN will be poor, and the electrode is easy to fall off during the subsequent wire bonding and bonding process; the other is voltage will increase

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