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^(TM) as sacrificial layer and NMD-3 developer as releasing solution. Four-inch sized SU-8 structures with different pattern and thickness of [email protected] have been successfully released from silicon substrate by this method. Experiments show that Omnicoat^(TM) 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^(TM) 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 [email protected] and aspect ratio of 4.1 have been fabricated. The analysis about the influence of Omnicoat^(TM) layer's thickness on integrity of SU-8 micro coils is also given in our work.