Area-Selective Atomic Layer Deposition of Crystalline BaTiO3

Patterned, crystalline BaTiO3 (BTO) films were formed directly on STO(001) surfaces using atomic layer deposition and restricting Ba and Ti precursor adsorption to STO(001) by passivating regions of the substrate with a polystyrene blocking layer. Patterns were prepared by spin-coating polystyrene onto STO(001), UV-crosslinking the polystyrene, and rinsing away uncrosslinked polystyrene with toluene. Amorphous 9-12 nm thick BTO films were deposited at 225 degrees C on polystyrene-patterned STO(001) surfaces. These films were crystallized upon annealing at elevated temperatures. Atomic force microscopy, scanning electron microscopy, and time of flight secondary ion mass spectroscopy were used after growth of BTO and removal of polystyrene resist and reveal BTO features with dimensions similar to the shadow mask. Reflection high-energy electron diffraction and X-ray diffraction show that BTO epitaxially crystallizes to the substrate, forming BTO(001), after annealing under vacuum at >= 770 degrees C with an oxygen partial pressure of 1 X 10(-6) Torr.