Method for preparing and bonding wafer-level chip used in micro-led

A method for preparing and bonding a wafer-level chip used in micro light emitting diode (Micro-LED), comprising:

• step 1, spin coating a negative photoresist on a complementary metal oxide semiconductor (CMOS) driving substrate to form a first photoresist layer on the CMOS driving substrate, and processing the first photoresist layer and the CMOS driving substrate by using a photolithography process to expose pixel areas on the CMOS driving substrate;
• step 2, patterning and growing metal electrodes on the pixel areas, and removing the first photoresist layer and a metal on the first photoresist layer;
• step 3, depositing a silicon dioxide (SiO2) insulation layer on the metal electrodes and a part of the CMOS driving substrate not covered by the metal electrodes, and spin coating a positive photoresist on the SiO2 insulation layer to form a second photoresist layer on the SiO2 insulation layer;
• etching a part of the SiO2 insulation layer on the metal electrodes, following by removing the second photoresist layer to obtain a first structure;
• step 4, bonding a Micro-LED chip with the first structure by using a bonding process;
• step 5, striping off a substrate of the Micro-LED chip after the bonding to expose a GaN layer of the Micro-LED chip;
• step 6, spin coating a positive photoresist on the GaN layer of the Micro-LED chip to form a third photoresist layer on the GaN layer of the Micro LED chip, and etching the GaN layer, a ITO layer and a metal layer after exposure to prepare Micro-LED pixels;
• step 7, corroding splashed ITO and a splashed metal on side walls of the Micro-LED pixels, and then removing the third photoresist layer;
• step 8, depositing, by using a composition process, an insulation layer on the Micro-LED pixels and a part of the SiO2 insulation layer not covered by the Micro-LED pixels, exposing a part of a GaN layer of each Micro-LED pixel and a bonded metal layer of an outer ring cathode of the CMOS driving substrate, and covering unexposed parts of the GaN layers of the Micro-LED pixels, the side walls of the Micro-LED pixels and the part of the SiO2 insulation layer not covered by the Micro-LED pixels;
• step 9, preparing a co-negative electrode by using a composition process, and the co-negative electrode being connected with the bonded metal layer of the outer ring cathode of the CMOS driving substrate.