Composite patterned substrate and preparation method thereof

Abstract

The invention relates to a composite patterned substrate and a preparation method thereof. The composite patterned substrate comprises a sapphire wafer. The maximum ratio of the diameter of circumcircles of the root portions of patterns of the surface of the wafer to the distance between two adjacent pattern central points is 0.95. The surfaces of the upper portions of the patterns are exposed. AlN layers with the thickness ranging from 15 nm to 35 nm are deposited between the root portions of the patterns. According to the composite patterned substrate and the preparation method of the composite patterned substrate, the advantages of the sapphire patterned substrate are reserved; in addition, the AlN layer which is in low lattice mismatching with GaN materials is introduced below the patterned substrate, and the GaN nucleation quality of the substrate in the later using process is effectively improved, so that the GaN growth quality is improved; moreover, the using efficiency of MOCVD can be effectively improved, and productivity is improved.

Description

technical field [0001] The invention belongs to the field of light-emitting diodes, and in particular relates to a multi-layer composite LED patterned substrate of light-emitting diodes and a preparation method thereof. Background technique [0002] Now mainstream LEDs use patterned substrates for epitaxial growth, such as Figure 9 , 10 As shown, on the one hand, the surface pattern provides a variety of growth crystal phase options for later GaN growth, making GaN change from traditional two-dimensional growth to three-dimensional growth, thereby effectively reducing the dislocation density in GaN-based LED materials and avoiding cracks On the other hand, because the array pattern structure increases the scattering of light, changes the optical circuit of the LED, forms diffuse reflection, and improves the light extraction efficiency. However, there is a 14% lattice mismatch rate between the sapphire substrate and GaN, which makes it difficult to nucleate and grow. In ord...

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Problems solved by technology

However, there is a 14% lattice mismatch rate between the sapphire substrate and GaN, which makes it difficult to nucleate and grow. In order to overcome the problem of difficult nucleation, after the substrate is baked at about 1000 ° C, the general treatment method for epitaxy is to grow a layer of thickness 20-40nm poor-quality low-temperature buffer layer, and then turn to high-temperature 3D growth of high-quality GaN. There is high-low temperature conversion in this process, which will reduce the efficiency of MOCVD and the lattice mismatch rate between GaN and the substrate. There are many high-line dislocations, and the temperature difference between different layers is large, resulting in the stress between different layers affecting the crystal performance.

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