Novel water-soluble protective adhesive for wafer's laser dicing

Abstract

In the field of high brightness LED, the requirements of miniaturization, output and yield are urgent. At the same time, low k dielectric layers are more and more widely applied in integrated circuit filed, in order to solve the problem of crosstalk and stray capacitance. Laser grooving technology is developed and be seen as an ideal solution for high brightness LED wafer and low-k wafer dicing. Because the chips dicing by non-contact laser grooving technology always have fewer defects than traditional blade sawing technology, such as surface chipping, backside chipping, metal peeling, inside cracks, and delamination. In this paper, two water-soluble adhesives containing different light absorbents are used in laser dicing process. Both adhesives have excellent absorption of special wave length light, and perfect wetting ability with substrates. In the LED wafers UV laser dicing, adhesive named LGP1020 can achieve a good dicing protective efficacy and no crack formed. The low-k wafer protected by LGP2020 after green laser grooving, chips are all in perfect condition. And the protective adhesive would not to be serious carbonized which difficult to clean, even if the power of the green light laser up to 7W. Experiment results show that both adhesives have a perfect protective effect and a widely usage range of laser power.