Surfactants as an additive to wet cleaning solutions for plasma etch residue removal: Compatibility to a porous CVD-SiCOH ultra low-k dielectric material

With decreasing feature sizes and integration of porous low-k dielectrics within the interconnect system of integrated circuits, plasma etch residue removal becomes challenging. Plasma cleaning processes are known to degrade low-k material's properties and wet cleaning becomes a promising alternative. Using water based cleaning solutions turns out to be critical as they may not be able to wet low-energy residue surfaces or to penetrate into small features. Lowering the surface tension of the solutions will be essential and the application of surfactants is a promising approach. We investigated the static and dynamic surface tension of different surfactant solutions in DIW and their compatibility to a porous CVD-SiCOH low-k dielectric. The choice of the rinsing solution applied after surfactant treatment turned out to be essential for removing residual surfactant species. Optical, electrical and structural analysis showed that in contrast to DIW an IPA-rinse is able to remove remaining surfactant species.