Novel Low Temperature Curable Photosensitive Negative-tone Polyimide with Higher Resolution and Reliability

Abstract

Hitachi Chemical DuPont MicroSystems (HDMS) has been developing photo sensitive negative-tone polyimides (PIs) as dielectrics for re-distribution layers (RDLs) in wafer level packages (WLPs) and as protection layers in semiconductor ICs. Photo sensitive negative-tone PIs can simplify the manufacturing process and ensure high reliability owing to their good mechanical properties, high thermal stability, and high electrical properties. On the other hand, since advanced packaging application such as Fan-Out WLP (FO-WLP) requires finer L/S design as well as higher reliability, lithographic performance of PIs has to be further improved and good cured film property should be achieved when cured at lower temperature (<230 °C). In order to meet these requirements, HDMS started the development of new PI which shows enhanced lithographic performance with good film property. In this paper, we will demonstrate our novel low temperature curable photo sensitive solvent developable negative-tone PI. By adopting a new photo-package to improve lithographic performance, this PI can achieve 3 μm via opening at 5 μm cured thickness and 5 μm via opening at 10 μm cured thickness with smooth pattern profile after cure. In addition, this PI shows good film property when cured at 200 °C and no electrical failure is observed during 300h bias-HAST using 2/2 μm L/S pattern.