Research on the Patterning Polyimide Layer Based on Laser Ablation Technology.

Polyimide (PI) has emerged as a critical material in advanced semiconductor packaging owing to its high temperature stability, low dielectric constant and loss, mechanical flexibility and stress relief, and chemical and moisture resistance. The passivation (PA) layer is usually formed by polyimide-based lithography technology during the whole process of IC packaging, such as bumping packaging, fan-in wafer-level packaging (FIWLP), and fan-out wafer-level packaging (FOWLP). A study on the patterning of a polyimide layer based on laser ablation technology is introduced in this manuscript. A series of samples with the structure of Si substrate/PI layer were prepared, and four different laser ablation conditions were applied to these samples. An inverted trapezoid shape of the opening structure was observed in the PI layer after the effect of laser ablation, which also indicated that the top width was about 6.4 ± 0.6 μm larger than the bottom width according to the measurement data based on scanning electron microscopy (SEM). Research on patterning PI layers based on laser ablation technology could also play an effective role in promoting the popularization of laser ablation technology in the advanced chip packaging industry.