As the title states, I partially etched some different material (Wafer 2238, 100 nm NPN) to create nanofeatures with blown out holes. With a thicker membrane, we can blow out the pores more (etch longer) without compromising the strength of the material (with regard to templating purposes). These membranes were fractured and coated with 6 nm of platinum. These images are only the NPN; not coated with gold or templated with MgF2.
Equivalent pore diameter histograms for partially etched substrates.
Minor Axis histograms of partial etch (0, 20, 40, 60, 80s) of Wafer 2238 (from top to bottom). Average length: 42, 48, 53, 56, 72 nm. Based on estimates of etch rate, the thicknesses of these membranes are (100, 80, 60 40, 20 nm, from top to bottom). Pores merge considerably below 40nm.
Zoom-in of wafer 2238. The scaly structures are residual pieces (siloxynitride?) used as a mask to create the thicker NPN materials. there also appears to be some conical shape to the pores, instead of anisotropic sidewalls.
Viewed off-normal, the thickness of the siloxynitride is appreciable.
40s etch crossection, 64 nm thick. (vibration hinders some resolution). The pores have a conical crossection.
80s etch aerial image. Residue pattern from the silicoxynitride is transferred through the nanomembrane’s volume.80s etch crossection. 23nm thick. The silicoxynitride acts as an etch mask (with poor selectivity) and is causing the texture at the surface.80s crossection. Shows the scalloped merged pores with sharp peaks.
I think the 2238-80s material is too weak to hold up to MgF2 processing, but there is hope for the 60s material.
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