Figure 1
From: Top-down fabrication of high-uniformity nanodiamonds by self-assembled block copolymer masks
Fabrication process flow in 8 steps, with colour legend at upper left indicating the material of each layer. Each subfigure corresponds to one fabrication step, with schematic side-view diagram, and text showing the specific process carried out in the particular step, together with SEM images taken after that step, showing resultant device morphology. All scale bars indicate 100 nm. Note that images for steps (a–c) are top view, and images for other steps were obtained with samples tilted at 45 degrees. (a) Polished bulk single crystal diamond, coated with ~30 nm SiO2 layer using PECVD, with AlOx hexagonal dot array patterned by BCP film using spin coating, SA and SIS. (b) Gentle O2 plasma treatment removes the polymer content in the BCP film, leaving AlOx hexagonal dot array pattern. (c) Directional plasma etching of SiO2, transferring the dot array pattern to SiO2 layer. (d) Directional O2 plasma etching of diamond, transferring the dot array pattern to bulk diamond, forming diamond pillars arranged in hexagonal array. (e) ALD of ~2 nm SiO2 coating to protect the sidewall of etched diamond pillars. (f) A short directional plasma etch removes SiO2 from bottom surfaces of the open gaps between diamond pillars. (g) The sample is exposed to a quasi-isotropic O2 plasma to undercut the diamond pillars. (h) The bulk diamond is immersed in HF acid to remove the residue SiO2 layer.
