HAST failure investigation on ultra-high density lines for 2.1D packages

Silicon interposers have a potential problem which is high cost. Therefore, a 2.1D package using organic material is proposed and the research becomes hot. In this paper, to check whether insulators have enough HAST reliability, biased HAST and unbiased HAST were performed using 40-micron thick insulators. The insulators meet our criteria from both insulation resistance between lines and series resistance points of view in Line/Space 2microns/2microns. Series resistance increase ratio of meander lines depends on the interruption due to putting off from HAST chamber. Therefore, it is preferable to measure the series resistance in-situ in HAST chamber. Based on the experimental results that the series resistance increase was found not only in biased HAST but also in unbiased HAST, a model was proposed. The model is that the series resistance increase is not simply in proportion to electric field strength but in proportion to sum of a fitting parameter and electric field strength. Based on the model, a material with filler may pass our criteria in Line/Space 1micron/1micron in 40-micron thick. Insulation resistance of Line/Space 1micron/1micron need to be evaluated as a future work due to no failure no failure in the experiments down to Line/Space 2microns/2microns during the biased HAST.