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.
The unwashed membrane has a definite “film” over it which makes the pores look textured. The MeOH & H2O seems to clear the pores up, but there are some places where there is remaining PVP that sticks to the inside walls of the pore.
The purpose of this post is to see if there is a pattern in the Pore Density vs. Pore Radius graphs at certain manufacturing conditions. The following wafers all have widths of 15nm and RTPs of 1000. The porosities range from 6.48% to 8.33%. **** note: the y-axis label should actually read “pore density (#/nm2)”…
This is the first post I have made with respect to the project proposed by Mark Dumont of the department of Biochemistry and Biophysics. As a reminder of the scope of the project Mark has shown an interest in using our pnc-Si membranes to separate detergent from trans-membrane proteins during the process of preparing samples…
Introduction Static endothelial cell cultures have been routinely performed and optimized on the µSiM platform for multiple membrane and cell types. In order to increase the physiological relevance of our device with tissue vasculature mimetics, we need to incorporate fluid flow to emulate shear stresses experienced by endothelium under physiological circulatory conditions. Recently Mehran has…
In Nottingham this summer, I attempted to use a Makerbot2 printer to create culture devices for SEPCON chips. I had varying degrees of success, but I was not able to get a good seal between the PLA and gaskets using only machined grooves. This would have limited our ability to do TEER and other 2-chamber…
Follow up to this post. As a brief reminder, I have performed 3-D simulations of separations in large and small volume systems. I have defined an effective diffusion coefficient that takes into account the membrane hindrance and compared this to free diffusion. As the Deff/D0 ratio drops, this means the membrane has a higher impact…
