Material characterization to model linear viscoelastic behavior of thin organic polymer films in microelectronics

In microelectronic packaging technologies organic thin film materials, e.g. photo resists acting as dielectric layers or solder masks, gain more and more importance due to trends towards miniaturization and high system integration. Therefore, a profound characterization of these materials is an important issue for reliable FEM simulations and improved process control. In this paper, viscoelastic material behavior of dielectric polymer thin films is characterized in time and frequency domain and implemented into ANSYS. The FEM results are compared to relaxation experiments for consistency check and it was found that material models from frequency data simulate a stiffer long term material behavior compared to data from time domain. The latter showed good agreement with accordant experiments. In addition to the standard macroscopic material characterization methods we initiated the steps towards a local microscopic material characterization method on device level using nanoindentation technique. The indentation creep compliance of organic thin films was measured and compared to standard methods. The advantage of analyzing in a small volume scale is to consider material characteristics of real processed thin films with thermal load histories as they appear in final products.