Fig. 2.

Fabrication process for DMs. (A) EBR on fused silica (or equivalent transparent substrate) with thickness t_resist that ultimately sets the height of the final structure (perspective view)_. (B) Inverse of the final metasurface pattern imprinted into the EBR by electron beam lithography and subsequent development of the pattern (top view). The boxed area is an expanded cross-section of the maximum feature width, w. (C) Initial TiO₂ deposition via ALD conformally coats sidewalls and top of the EBR and exposed substrate (side view). TDMAT molecule used for ALD is also shown. (D) Completed deposition of the TiO₂ yields a film thickness greater than half the width of the maximum feature size, t_film ≥ w/2. (E) Exposed tops of the TiO₂ metasurface and residual EBR after reactive ion etching with a mixture of Cl₂ and BCl₃ ions (top and side view). (F) Final DM after removal of remaining EBR (top and side view).