Flip chip with patterned current expansion layer and manufacturing method of flip chip

Abstract

The invention relates to a flip chip with a patterned current expansion layer and a manufacturing method of the flip chip. The manufacturing method comprises the steps of growing an epitaxial layer isgrown on a substrate; dividing the epitaxial layer into a P region and an N region by etching; fabricating the current expansion layer on the P region, forming a hole in the current expansion layer by etching to fabricate a patterned hole-shaped structure, wherein the hole depth is smaller than the thickness of a film layer of the current expansion layer; fabricating a reflecting layer on the current expansion layer with the hole-shaped structure; sequentially fabricating a passivation layer, a protection layer and a metal electrode on the corresponding P region and the N region; and thinningthe substrate, and cutting to form each independent chip. By the manufacturing method, the ohmic contact area between the reflecting layer and the current expansion layer can be expanded, the contactarea of the current expansion layer and a P-GaN layer is reduced, the problem of unfavorable contact of the reflecting layer and the P-GaN layer is prevented, the current injection efficiency is improved, the absorption of the current expansion current on light is effectively reduced, the interface reflection proportion is improved, and moreover, the adhesion of each film layer structure of the flip chip is improved by roughening contact.

Description

technical field [0001] The invention relates to the field of chip manufacturing, in particular to a flip chip with a patterned current spreading layer and a manufacturing method thereof. Background technique [0002] The existing conventional LED chip production is to fabricate an epitaxial layer including an n-GaN layer, a multi-quantum well light-emitting layer and a p-GaN layer on a substrate (generally sapphire material), and a transparent layer is formed on the p-GaN layer. The conductive layer (generally using ITO material) is made of an n-type electrode and a p-type electrode on the n-GaN layer and the p-GaN layer respectively. Since the refractive index of GaN is about 2.5, and the refractive index of air is 1, the refractive index difference between the two is relatively large, so there is a serious total reflection phenomenon on the interface between the LED chip and the space, resulting in the formation of the light-emitting layer in the LED chip. Only a small pa...

AI Technical Summary

Problems solved by technology

Since the refractive index of GaN is about 2.5, and the refractive index of air is 1, the refractive index difference between the two is relatively large, so there is a serious total reflection phenomenon on the interface between the LED chip and the space, resulting in the formation of the light-emitting layer in the LED chip. Only a small part of the light can be emitted, and most of the light is confined inside the LED chip due to the phenomenon of total reflection, which affects the surface light efficiency of the LED chip

In addition, the transmittance of the transparent conductive layer to visible light is not 100%, and part of the light emitted by the LED chip will be absorbed by it, reducing the brightness of the chip.

[0003] At present, for example, there is a technology to increase the light extraction efficiency by roughening the surface of the LED chip and increasing the thickness of the p-GaN layer. However, the requirements for dry or wet etching in roughening the surface of the p-GaN layer are relatively high, and the production process is not easy. At the same time, due to the direct contact between the transparent conductive layer and the p-GaN layer with a rough surface structure, it will cause the ohmic contact problem between the transparent conductive layer and the p-GaN layer in the LED chip, that is, the surface contact between the two The resistance increases, which in turn leads to an increase in the forward voltage of the LED chip, which eventually leads to a decrease in the current injection efficiency of the LED chip

Another example is to increase the transmittance of the transparent conductive layer by thinning it, but this will increase the sheet resistance and increase the power consumption of the chip.

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