Method for preparing LED chips with positive, inverted and inverted trapezoidal mesa substrates by stealth dicing

Abstract

A method of preparing LED chips with upright, inverted and inverted trapezoidal substrates through invisible cutting comprises the following steps: growing an epitaxial layer on the front of a substrate, and forming multiple LED units; thinning the substrate; focusing a laser focus inside the substrate, and performing cutting to form a first modified layer and a second modified layer; making the formed multiple leftward and rightward modified layers relative to a runway located in the same slopes at the left and right sides of the runway respectively to form a base plate; pasting the back of the base plate to a blue film, and putting the blue film on a splitting machine; and performing splitting by aligning a chopper with the centerline of the runway, wherein delta(x) is the unit distance of movement of the laser focus along the horizontal direction, and delta(z) is the unit distance of movement of the laser focus along the vertical direction. The method has the advantages of simple process and high efficiency, and can effectively improve the light extraction efficiency of LED.

Description

technical field [0001] The invention belongs to the field of semiconductor preparation, in particular to a method for stealth cutting and preparing LED chips of forward, reverse and reverse trapezoidal table substrates. Background technique [0002] Since the 1990s, GaN-based LEDs have attracted widespread attention and achieved rapid development. LED has significant advantages such as adjustable wavelength, light and flexible, low energy consumption, low working voltage, directional light emission, no pollution, long life, fast response time, etc. It has great potential in white light lighting, visible light communication, polymer curing, sterilization and disinfection market value or potential application value. [0003] The luminous efficiency of LED is mainly affected by two factors. One is the internal quantum efficiency, that is, the efficiency of converting the injected electric energy into light energy, which mainly depends on the epitaxial quality of the semicondu...

AI Technical Summary

Problems solved by technology

Surface cutting is a laser ablation process. Surface cutting technology is used to prepare inverted trapezoidal table-shaped LED chips. The angle of inverted trapezoidal table is small, and the effect of improving light extraction efficiency is limited; light-absorbing by-products will be produced during laser ablation. Auxiliary chemical cleaning process to remove, the process is more complicated (document [2]: IEEE Photonics Technology Letters 21, 1078 (2009))

Images