Charge-Pattern Indicated Relaxation Dynamics and Glass Transition of Polymer Thin Films Studied by Atomic Force Microscopy

Polymers are widely used as dielectrics in microelectronics. As the thickness of polymer films decreases to the submicrometer or nanometer scale, abnormal relaxation deviations from the bulk matrix are expected. Evaluation of the relaxation dynamics in an efficient and quantitative manner is highly desired. Utilizing this patterned charge as an indicator, we demonstrate here that the polymer relaxation dynamics and glass transition temperature (<i>T</i>_g) of thin polymer films can be investigated by monitoring the charge decay behaviors. This approach of charge patterning combined with atomic force microscopy is more facile to evaluate polymer relaxation behavior with direct contrast between charged and electrically neutral domains versus conventional polymer <i>T</i>_g and relaxation dynamic measurements. This study also illuminates the coexisting processes of polymer relaxation and trapped charge decay in thin polymer film. This sheds light on the microscopic mechanism of charge storage and relaxation properties in the polymer