Epitaxial wafer structure for flip LED chips and making method thereof

Abstract

The invention provides an epitaxial wafer structure for flip LED chips and a making method thereof. The epitaxial wafer structure for flip LED chips comprises a support substrate, a lattice matching layer, a connecting dielectric layer, an N-type semiconductor layer, an active layer and a P-type semiconductor layer, all of which are formed sequentially, wherein the connecting dielectric layer is provided with periodically arranged columnar structures. The connecting dielectric layer provided with periodically arranged columnar structures exposes part of the lattice matching layer. The N-type semiconductor layer covers the connecting dielectric layer provided with periodically arranged columnar structures and the lattice matching layer. The epitaxial wafer structure and the making method thereof are conductive to increasing the internal quantum efficiency and the external quantum efficiency of flip LED chips.

Description

technical field [0001] The invention belongs to the field of semiconductor optoelectronic chip manufacturing, and in particular relates to an epitaxial wafer structure for flip-chip LED chips 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. In the field of lighting, especially in the field of high-end lighting, the improvement of luminous brightness is the never-ending pursuit of scientific researchers in the LED industry. In recent years, the most active technology in improving LED luminance is undoubtedly the patterned substrate technology. The patterned substrate technology not only improves the crystal quality of LED epitaxy by reducing latt...

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Problems solved by technology

[0004] The high-voltage LED chip structure is generally formed after the epitaxial layer is formed, and the isolation groove is formed by photolithography, and then the isolation groove is filled with insulating material, and finally electrodes are made on each insulated and separated epitaxial layer to form a series structure; although this The structure can improve the luminous brightness of the LED, but the process of forming the isolation groove and filling the insulating material greatly increases the manufacturing cost of the chip. Not only that, but also reduces the reliability of the LED chip to a certain extent. For example, due to the existing etching If the uniformity does not meet the requirements, the deep groove etching is not clean, which will eventually lead to leakage and reduce the breakdown resistance of the LED chip, etc.

[0005] Although the vertical LED chip structure does not need to etch the N-region material, it reduces a part of the production cost of the LED to a certain extent, and is suitable for high-current injection, which can further improve the luminous brightness of the LED chip. However, like the high-voltage chip, the vertical Structured LEDs also need to form isolation grooves, which greatly increases the production cost of LEDs. Not only that, vertical structure chips also need to peel off the growth substrate, which again increases the production cost of LED chips and reduces the cost of LED chips. yield and reliability

[0006] The flip-chip LED chip structure is to flip-chip-weld the front-mounted chip on a substrate with good electrical and thermal conductivity, so that the light-emitting epitaxial layer with relatively concentrated heat generation is closer to the heat-dissipating heat dust, so that most of the heat is exported through the substrate instead of poor heat dissipation. The sapphire growth substrate is exported, which alleviates the heat dissipation problem of the LED chip to a certain extent and improves the reliability of the LED chip; and, when the area of ​​the LED chip is determined, compared with other structures of LED chips, flip-chip The light-emitting area of ​​the LED chip with the structure is larger, so it has more advantages in the face of the challenge of high luminous brightness in the high-end lighting field; however, the flip-chip LED chip structure emits light on the N side, because the refractive index of sapphire is lower than that of nitride The refractive index of gallium, so the light emitted from the epitaxial layer will be reflected on the interface between sapphire and the substrate, resulting in more light not being emitted, especially the patterned substrate currently used in the mainstream LED chip structure has scattering And diffuse reflection, it is easier to cause more light to not be emitted, reducing the light efficiency; but if the patterned substrate technology is not used, the internal quantum efficiency of the LED chip cannot be fully utilized

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