This week I tried to run a few “eq-tests” with some samples from wafer 187 to get some hydraulic permeability value for our membranes to see how they compare to the polymer filters used in the microcon and nanosep systems. Unfortunately I have no results to report, of the two samples I tested one broke…
I’ve been doing some reading, and came across this article by researchers at Sandia Nat’l Labs. They are looking at the stress evolution in thin films, and have observed “nanovoids” in their amorphous silicon. Here is a cross-sectional TEM image (XTEM) from the article. Floro et. al. PRL 2003 There are three layers of a-si…
This week I set up some diffusion experiments with the inner membranes of wafers 187 and 310. From the TEM images posted previously, we see that these inner membranes have what appear to be either very small pores or small divots that do not pass entirely through the membrane. I allowed the protein standards to…
Link to “A closer look at separations” We recently bought purified proteins that I will use to build a molecular weight ladder for membrane separations. I initially dissolved these proteins in salt solution and spun in an ultracentrifuge to remove aggregations. I then sized the proteins using our Malvern Zetasizer, which gives hydrodynamic radius, assuming…
An important result of last weeks experiment showed that Antimony (Sb) doped substrates had no pinhole defects; however, Phosphorous doped substrates from the same batch had many very small pinholes. This agrees with a previous experiment: Antimony wafers have shown no pinhole formation. I propose a model that aims to explain:1) Why we are not…
This week’s production included wafers of antimony (Sb) and phosphorus (P) doping. Process parameters The deposition heater was re-brazed prior to this deposition. We were concerned with the original brazing job because there were areas with “globs” of material and cracks in the solder. The new braze covers most of the surface, and although is…
Process Summary for the week of 12/3 -12/10/2007: Simpore Process Flow.xls JP
I reran a set of hydraulic permeability tests at 16.56psi (3500RPM) hoping that this would clarify the previously collected data at the 21.63psi (4000RPM) and the 33.79psi (5000RPM) range that did not seem to agree with the trend of the other data points. As shown above this point still does not seem to be in…
We have previously discussed how the membranes near the center of the wafer have very small pores, while as you progress outward larger pores begin to appear. I tested one of these central membranes from wafer 304 (TEM sample, position -1,0) using our standard fluorescence microscope based assay. I observed obvious rhodamine diffusion through this…
I took a closer look at some of Lingyun’s samples today, and captured some interesting TEM images. wafer 205 with 10 nm Ti @ 35kx wafer 205 with 10nm Ti @ 250kx wafer 205 with 10nm Ti & 10nm Au @ 35kx wafer 205 with 10nm Ti & 10nm Au @ 200kx The higher mag….