Wet releasing and stripping SU-8 structures with a nanoscale sacrificial layer

This paper presents a new method of wet releasing SU-8 structures using very thin Omnicoat™ as sacrificial layer and NMD-3 developer as releasing solution. Four-inch sized SU-8 structures with different pattern and thickness of 65 μm have been successfully released from silicon substrate by this method. Experiments show that Omnicoat™ layer is very helpful to strip SU-8 molds in which metal structures are electroplated. SU-8 can be removed directly using remover if there is an Omnicoat™ layer between the substrate and SU-8 and the electroplated structures is with large dimension. In the case of electroplated structures with small feature size, SU-8 can be removed by combining wet stripping and plasma etching. Nickel micro coils with linewidth of 10 μm and aspect ratio of 4.1 have been fabricated. The analysis about the influence of Omnicoat™ layer’s thickness on integrity of SU-8 micro coils is also given in our work.