Flip-chip LED chip structure and manufacturing method thereof

Abstract

The invention provides a reverse LED chip structure. A two-sided patterned substrate is adopted, and microlens arrays with the light condensation effect are arranged on the two opposite surfaces of the two-sided patterned substrate, so that the light-emitting brightness and the axial light-emitting brightness of a reverse LED chip are improved on the premise that the crystalline quality of an LED epitaxial layer is not affected. The invention provides a manufacturing method of the reverse LED chip structure. A first microlens structure arranged in an array is manufactured on the first surface of the substrate, the photoetching self-alignment process is achieved through light emission of the LED chip and in combination with the characteristics of the first microlens structure arranged in the array on the first surface of the substrate in the follow-up process, a mask layer on the second surface of the substrate is manufactured on the premise that no mask plate or alignment is needed, finally, patterning of the second surface of the substrate is achieved through the etching process, a second microlens structure arranged in an array is formed on the second surface of the substrate, and the reverse LED chip with the two-sided patterned substrate is manufactured.

Description

technical field [0001] The invention belongs to the field of semiconductor optoelectronic chip manufacturing, and in particular relates to a flip-chip LED chip structure and a manufacturing method thereof. Background technique [0002] Since the commercialization of GaN-based LEDs in the early 1990s, after more than 20 years of development, its structure has become mature and perfect, and it has been able to meet people's current needs for lighting decoration; but it must completely replace traditional light sources and enter the lighting industry. field, the improvement of luminous brightness is the never-ending pursuit of scientific researchers in the LED industry. Under the premise that the internal quantum efficiency (already close to 100%) can be improved, researchers in the LED industry turned their attention to the external quantum efficiency, and proposed various technical solutions and methods that can improve the light extraction rate, such as graphics Substrate t...

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Problems solved by technology

[0004] Compared with LED chips, flip chips can solve the problem of difficult heat dissipation. Commercial LED chips are mostly grown on sapphire substrates, and then fixed on the packaging bracket. Such LED chips mainly dissipate heat through conduction, while sapphire substrates Because it is thicker, it is difficult to export heat, and heat accumulation in the chip will affect the reliability of the chip, increase the light decay and reduce the life of the chip; the problem of low light efficiency, the electrode blocking light, will reduce the light output of the chip; current crowding will increase the voltage of the chip , these will reduce the light efficiency of the chip; the problem of complex packaging, the voltage of a single LED chip is about 3V, so it is necessary to change the voltage or connect the package in series, which increases the difficulty of packaging and application, and the difficulty of the process increases. The reliability of the whole chip becomes worse

[0005] The flip-chip structure with so many advantages will become the most promising GaN-based LED structure that can greatly increase the brightness of LEDs in the future. However, the LED chip of the flip-chip structure emits light on the N side. On the one hand, due to the refractive index of sapphire The refractive index is lower than that of gallium nitride, so the light emitted from the epitaxial layer will be totally reflected on the interface between sapphire and the substrate, resulting in more light not coming out and reducing the light extraction efficiency; on the other hand, due to the growth substrate surface pattern Existence, at the interface between the substrate and the epitaxial layer, more light will be reversed from the N side to the P side again, which further affects the light extraction efficiency of the flip-chip LED chip. If the flip-chip does not use a patterned substrate, Instead, use a flat substrate, which will seriously affect the crystal quality of the epitaxial layer

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