Hafnium oxide itself doesn't seem to be proprietary, and neither does the process of producing thin films that have ferroelectric properties[1]. My guess is that they've made some additional modifications to the compound and/or process.

I'm venturing way outside of my field here, so I could be completely wrong.

[1]: http://aip.scitation.org/doi/abs/10.1063/1.3634052 (search for the title in Google Scholar to get a PDF)