In an attempt to help wet the pores prior to permeability experiments, I’ve started soaking assembled SepCons in a %50 ethanol solution. Each SepCon is inserted into an eppendorf so that the membrane side is fully submerged. I realized that in my last post, I was soaking multiple samples in a beaker which did not…
I’ve recently been exploring hydraulic permeability using the pressure cell. As you may recall, the majority of our permeability measurements have been done in the centrifuge (EQ format or closed bucket). The pressure cell allows for a more accurate measurement of permeability because it is not affected by changing water levels or variable driving pressures….
Last week, I annealed a few amorphous 15 nm TEM grids in the RTP. We have always speculated that the stress from the bulk silicon was a necessary condition to induce pore formation and I wanted to confirm this. I picked six different temperatures: 600, 700, 750, 800, 900, and 1000 C. They were annealed…
The current method of testing water permeability through SepCons is to place a volume of water inside a SepCon and spin it inside a centrifuge. After a set period of time, the volume passed is collected. The “approximate” permeability can be calculated as: volume passed/(pressure*area*time of experiment) in units of uL/PSI/cm^2/min. The reason this is…
In the last production cycle, there were several wafers annealed for longer than our standard 1 minute RTP soak time. Recall in my earlier post, I observed a significant change in pore morphology in a 30 nm thick silicon membrane annealed at 1050 C for 1 min/5 min. In this series of experiments, we observe…
A while back, we discussed leaving the rotation stage off during the a-Si deposition to induce a thickness gradient over a single wafer. The purpose of this experiment was to explore the different morphologies vs. thickness at a given RTP treatment. We estimated that we could cover a 3x thickness range over a 8 cm…
A simple hydraulic permeability study was performed to determine whether carbonization would negatively impact water transport through the membranes. 5 slit square SepCons from SC 471 were carbonized and put in the ultra-centrifuge with a 500 uL starting volume. The samples were spun for 10 minutes at 3000 RPM (equiv to 4.95 PSI starting). SC…
SiMPore has been collaborating with the Infotonics Center to scale our SepCon production to a 6-inch wafer. The wafers are patterned and deposited at their facility and then brought back to UR where we anneal and etch. This week, we etched several wafers and the initial results look promising. The big news is that we…
During the last production run, we experimented with varying the RTP annealing time (1 min vs. 5 min) at three different RTP temperatures (1050 C, 1100 C, 1150 C) in a 30 nm thick membrane. Below are the TEM micrographs with corresponding histograms and average pore diameter/porosity plot. Of note is the 1050 C anneal…
During the history of pnc-Si fabrication, we have always observed that pore formation is intimately related to the crystallization process. In general, large nanocrystals in a film correspond with larger pore diameters. A partially crystallized film will have a low density of films. Following the work that describes crystallization of a-Si in terms of kinetic…