I am developing a process for fabricating microporous Parylene Liftoff membranes. I am interested in these as a more flexible substrate for cell culturing. Parylene is relatively strong (compared to say pdms), so it is feasible to work with lifted off pieces of membranes on the order of 1 micron or less in thickness. I list…
The NSF STTR phase I project officially ended last week, and we are writing the final report and preparing to submit a Phase II proposal. I will attempt here to summarize the program achievements and list some of the persisting technical issues we are facing. Program Technical Objectives: Optimize nanoporous silicon nitride (NPN) membrane properties…
Josh Miller and Elizabeth Hirschman (RIT co-op student working on STTR lift-off project) obtained preliminary successful results lifting off ~1 in2 sections of NPN membrane where the nanopores were only transferred into the nitride layer in a microporous pattern (ø3 µm pores, hex-close-packed on 6 µm pitch). Details of process are given below. Bruce…
Summary The CEIS project ended in June, and I am summarizing the last few weeks of activities below by Josh and me. We did a little more work on reducing the SU-8 film stress through the processing conditions. We also succeeded in obtaining smooth poly-Si films in the RIT SMFL. We made a few test…
Summary: Annealing to above glass transition T (200 C) doesn’t reduce film stress. Adjusting post-exposure bake protocol seems to reduce it. A short post to document my efforts at reducing tensile stress in SU-8-3000 coatings by annealing in vacuum to its glass transition temperature (200 °C according to MicroChem). This is in relation to the…
Background Details: Josh Miller & I have made some recent progress in the NPN LO work. We had several ø6″ wafers w/ 100 nm of thermal oxide processed by Rogue Valley, wherein they deposited 650 nm of poly-Si (LP-CDV) followed by 50 nm of low-stress SiN (LP-CVD). Josh added the a-Si + SiO2 layers at…
This is a summary I wrote ~3 weeks ago of the work Josh Miller and I are doing under the CEIS grant for NPN Lift-off. Summary: Josh and I have been working for about four weeks so far on this program. During that time we have done preliminary lift-off (LO) tests on two wafers: one…
I attended the 2014 Gordon Research Conference (GRC) on Fuel Cells in August. For those of you not familiar with Gordon conferences, I will make a plug for them as a great venue for learning much detail and interacting closely with many of the major contributors in a specific field. GRC has a wide variety…
I posted previously about an issue we have with needing to strip the native oxide from the sacrificial silicon layer prior to performing the through-pore etch with XeF2 that enables separation of the oxide membrane from the wafer substrate. The issue is that the membrane is generally attacked by whatever etch method is used to…
Today, I finally demonstrated liftoff of microporous SiOx from a bare Si wafer. The sample is a 2 x 2 cm section of wafer 209A02, which has a 100 nm layer of TEOS SiOx that stress stabilizing anneal. The film was patterned with close-packed ø3 µm pores (6 µm pitch) using S1813 resist, G-line stepper…
