Charge dissipation layer optimisation for nano-scale electron-beam lithography pattern definition onto diamond

This paper demonstrates that the pattern feature size achieved for electron beam lithography (EBL) on diamond substrates can be minimised through optimisation of the thickness of a surface deposited metallic discharge layer. The purpose and benefits of a charge dissipation layer are presented and the subsequent trade-off with feature size examined. 5 nm of Al is demonstrated to be the optimum thickness of charge dissipation layer for polymethyl methacrylate (PMMA) resist on polycrystalline diamond as the feature size retains a similar variance to thicker layers, has good reproducibility and ultimately produces the smallest feature sizes. PMMA can be used as either a metal deposition mask, or an etch mask for SiO2 which in turn can be used as an etch mask for diamond. Using this process we have demonstrated pattern transfer and metallisation of features onto diamond and SiO2 coated diamond down to a dimension of 20 nm.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Demonstrate that e-beam feature size scales with discharge layer thickness on diamond. ► Illustrate the impact of not having a thick enough discharge layer. ► Concluded that the optimum thickness of Al discharge layer for e-beam lithography is 5 nm. ► Demonstrate that the above highlights also stand for SiO2 coated diamond.