The effect of soft bake on adhesion property between SU‐8 photoresist and Ni substrate by molecular dynamics simulation

SU‐8 photoresist is a negative, epoxy‐type, near UV photoresist and is commonly used in micro electro mechanical systems (MEMS) and other thick resist application fields. However, poor adhesion strength between SU‐8 photoresist and metal substrate makes it difficult to bind, even contributes to the lithography failure. This significantly restricts the improvement of image resolution and depth‐to‐width ratio. As soft bake temperature and time are important for the interfacial adhesion property, in this article, molecular dynamics (MD) simulation was performed to investigate the effects of these two parameters on adhesion property between SU‐8 photoresist and Ni substrate. According to the adsorption theory, the simulation results were analyzed and validated by experiments. It is shown that with increasing soft bake temperature the adhesional work firstly increases and then decreases, and with increasing soft bake time the adhesional work decreases. This study provides theory basis for the confirmation of soft bake parameters. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013