Effects of supercritical carbon dioxide treatment on bending properties of micro-sized SU-8 Specimens

The bending properties of micro-sized photoresist patterns are quantitatively evaluated using microsized SU-8 cantilever type test specimens to clarify the effects of supercritical carbon dioxide-treatment (ScCO2-treatment). The SU-8 specimens were treated with different types of treatments before the bending tests, which were ScCO2-treatment, heat-treatment, and non-treatment of specimens. In addition, FT-IR analysis of these specimens was performed to clarify the relationship between the degree of crosslinking and the bending properties. The values of Young's modulus, yield stress, and bending strength in heat-treated SU-8 specimens are all greater than those of the non-treated ones because of a higher degree of crosslinking. On the other hand, the bending properties in SU-8 only change slightly by the ScCO2-treatment in spite of the fact that the degree of the epoxide rings in SU-8 is significantly lower. This result suggests that ScCO2 does not only affect the bending properties by influencing the degree of crosslinking, but ScCO2 also seems to work as a plasticizer. (C) 2011 Elsevier B.V. All rights reserved.