3D self-assembling of SU-8 microstructures on silicon by plasma induced compressive stress

This paper presents the development of suspended movable microstructures made of SU-8 photoresist where compressive stress leads to 3D self-assembled microstructures. Internal compressive stress in the photoresist is induced by an SF₆ based plasma process. Clamped-clamped beam structures have been fabricated to characterize the stress depending on the plasma duration and the lengths of the beams. A compressive stress of 48 MPa was calculated for a 3 minute plasma. X-ray photoelectron spectroscopy (XPS) analysis has been performed to characterize the surface of the structures. These mechanical properties could be used to make 3D self-assembled structures for applications in biological sciences.