Burst Pressure Tests of Annealed and Unannealed SiO2 Membranes
Overview
I burst pressure tested TEM chips with 1×1 mm windows of 100 nm SiO2 that were both annealed and unannealed (provided by JP and Josh Miller). In our experience it seems that the forming gas (H2/N2) annealed chips are stronger and never wrinkle. These burst pressure tests were performed in an attempt to quantify this robustness.
Methods
Three Annealing Conditions
– No Anneal
– N2 Anneal for 1 hr
– H2/N2 (Forming Gas) Anneal for 1 hr
Unannealed chips were processed yesterday (9/3/14) was were wrinkled.
N2 annealed chips were processed on __________ and were wrinkled by the time this test was carried out. They were reported to be flat immediately following anneal and likely wrinkled within ~2 weeks. The wrinkling appeared comparable to the unannealed chips.
H2/N2 Forming gas annealed chips were processed on _________ and were still perfectly flat.
Data
| Unannealed | N2 Anneal | H2/N2 Anneal |
| 2.0 psi | 2.7 psi | 3.3 psi |
| 2.2 | 3.0 | 3.5 |
| 2.2 | 3.1 | 3.7 |
| 2.2 | 2.9 | 3.7 |
| 2.2 | 3.1 | 3.7 |
| 2.3 | 2.9 | 3.8 |
| 2.2 | 3.2 | 3.6 |
| Mean = 2.2 +/- 0.1 SD | Mean = 3.0 +/- 0.2 SD | Mean = 3.6 +/- 0.2 SD |
Conclusion
Forming gas annealed membranes are indeed significantly stronger than unannealed chips. While N2 annealed membranes were wrinkled and appeared similar to the unannealed membranes under the microscope, they had significantly higher burst pressures. Additionally, I was impressed with how tightly clustered the data was for condition.
Thanks to Josh Winans for helping me and reminding me how to carry out burst pressure tests!
Last week (23 Feb 2015), JP and Josh made 300 nm thick, 500×500 micron flat oxide membranes. Using the somewhat leaky flow setup we have at SiMPore, Josh measured BP of 60+ PSI when flow was applied against the membrane side and 12 PSI when applied against the well side. N = 2 for both tests. The leaky setup may be over-estimating the BP of 60+. Based on Tom’s other data, the theoretical BP should be ~42 PSI.