Method for fabricating light-emitting diode (LED) chip

Abstract

The invention provides a method for fabricating light-emitting diode (LED) chip. The method comprises the following steps: (1) forming a N type nitride layer and a P type nitride layer on a sapphire substrate and a multiquantum trap layer between the N type nitride layer and the P type nitride layer to obtain a LED wafer; (2) performing right side scribing to the LED wafer by laser irradiation technology until scribing in to the substrate; (3) etching the LED wafer in the step (2) by etching technology and fabricating a N electrode and a P electrode; (4) performing back side grinding, thinning and splitting to the LED wafer in the step (3) to obtain the LED chip. In the invention, the right side scribing is performed before fabrication of the N and P electrode; the melted level generated in the laser irradiation cutting formation and the residues deposited on the LED wafer side and the surface electrode are removed by the etching process in the fabrication of N and P electrode; thereby, the photoelectric parameter of the chip and the yield rate of the LED chip are optimized.

Description

technical field [0001] The invention relates to a method for manufacturing a light-emitting diode chip, in particular to a method for cutting a GaN epitaxial wafer based on a sapphire substrate into a light-emitting diode chip. Background technique [0002] GaN-based III-V nitrides are an important wide-bandgap semiconductor material with a direct bandgap. Due to its unique bandgap range, excellent optical and electrical properties, and excellent physical and chemical properties, it can be used in blue and green , violet, ultraviolet and white light-emitting diodes, short-wavelength laser diodes, ultraviolet detectors, power electronic devices and other optoelectronic devices and electronic devices, as well as semiconductor devices under special conditions, have been widely used. At present, the sapphire substrate is one of the most commonly used substrates for the epitaxial growth of heterogeneous GaN light-emitting diodes. The nitride-based light-emitting diode wafer is ob...

AI Technical Summary

Problems solved by technology

[0003] Figure 1a , 1b It is a process for forming a traditional light-emitting diode chip. On a sapphire substrate 14, an N-type nitride layer 13, a P-type nitride layer 11, and a multi-quantum layer between the N-type nitride layer 13 and the P-type nitride layer 11 are grown. After the well layer 12 is etched to expose the N-type layer 13 by an etching process, the N-electrode 20 and the P-electrode 10 are fabricated. After the back grinding and thinning, laser scribing is used, and then the light-emitting diode chip is obtained by splitting with a splitter. The splitting process of the splitter In the above, the crack extends from the sapphire substrate 14 to the contact surface of the sapphire substrate 14 and the N-type nitride layer 13, however, based on the heteroepitaxial structure of the nitride layer on the sapphire substrate 14, it has a large Lattice mismatch, there is a large stress, when the crack reaches the contact surface, it cannot crack along the predetermined direction, and when the crack cracks along the epitaxial layer, it will lead to the generation of bad light-emitting diode chips

The shape of the light-emitting diode chip obtained by this method is irregular, the yield rate is low, and the edge of the chip is rough.

[0004] In order to avoid the above defects, after etching to expose the N-type layer 13, making the N electrode 20 and the P electrode 10, the laser is used to irradiate and cut from the front of the light-emitting diode wafer, so that the substrate is exposed or cut into part of the substrate, such as Figure 2a , 2b As shown, the light-emitting diode wafer obtained by this method usually forms a melting layer 16 on the contact surface cut by laser irradiation. Although the light-emitting diode chip with a relatively regular shape is obtained, the yield rate has also been greatly improved, but in practice On the one hand, the residue obtained by laser treatment is easy to deposit on the side of the light-emitting diode chip or deposit and cover the surface of the electrode to be formed, and the Ga ions attached to the side will also seriously affect the photoelectric parameters of the light-emitting diode chip. In addition, the opacity of the melting layer 16 will also affect the luminous efficiency; on the other hand, the laser burns the GaN layer often occurs during laser scribing. After the laser burns the GaN, the photoelectric parameters of the chip will change, especially the increase of the leakage parameter. , will cause the chip to be scrapped

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