Record porosity and size in 15 nm pnc-Si
As a continuation of the substrate bias series, I deposited a 15 nm film with 05 W substrate bias and annealed at 1000 C. TEM shows that this condition generates a 13.4% porosity and a max pore size of ~40 nm! Here is a comparison of all the bias conditions tested thus far:
I believe that the 05 W bias generates a “sweet spot” in the film stress that promotes pore formation. The next experiments will test powers to either side of 05 W (02 W and 10 W) and also look at low substrate biases on thicker films.
This wafer had a low pinhole density (I counted < 10 membranes with >= 1 pinhole). This wafer was deposited immediately after a chamber clean and had the high pressure protective oxide. The burst pressures for the seven samples I tested were: 3.26, 6.2, 9.6, 15.2, 15.4, 18.0, 18.4 PSI. For all these samples only one slit burst at the listed pressures.
very interesting result! I am not sure which TEM corresponds to which curve. Also, could you compare the porosity in these 4 films?
Thanks
For the TEM, from left to right it is 0, 5, 25, 50 W.