Process of new negative photo-dielectric polymer ALX with high reliability

We present the results of study on the manufacturability and reliability of ALX211 polymer in wafer level packaging processes and structures. Previously, the processing windows of ALX211 polymer and the impact of the delays between processing steps on the stability of the process were studied. In this paper, we present a new method to achieve high resolution using ALX211, by putting a certain period of dwell time between treatment with AP903 and processing ALX211, and utilizing relatively low exposure dose. In addition, we present reliability results comparing the performance of polyimide, BCB, and ALX211 as evaluated in a bump-on-polymer test structure. Results of board level temperature cycling testing are presented.