Self-aligned growth of organometallic layers for nonvolatile memories: Comparison of liquid-phase and vapor-phase deposition

Deposition methods for the self-aligned growth of organometallic charge-transfer complexes for use as a conductivity-modulated, nonvolatile switching layer are presented. First, a deposition from liquid phase is investigated and a model for film growth is derived. Then, a deposition technique for charge-transfer complexes, namely selective organic vapor-phase deposition, is introduced which excels in selectivity and homogeneity. In particular, silicon dioxide layers exposed to the precursor molecules during processing remain completely uncovered, whereas copper pads in contact holes are rapidly filled with the desired layer of the charge-transfer complex. Then, both deposition methods are compared regarding reproducibility, selectivity, homogeneity, and the ability to selectively grow thin films in small structures with diameters below 200 nm. Finally, electrical switching properties are investigated and the switching mechanism for the present charge-transfer complex is discussed.