| AVS 54th International Symposium | |
| Thin Film | Monday Sessions |
| Session TF-MoA |
| Session: | Emerging Topics in Atomic Layer Deposition |
| Presenter: | E. Robertson, University of Maryland |
| Authors: | E. Robertson, University of Maryland I. Perez, University of Maryland L. Henn-Lecordier, University of Maryland S.J. Son, University of Maryland S.B. Lee, University of Maryland G.W. Rubloff, University of Maryland |
| Correspondent: | Click to Email |
The very high conformality for thin film deposition in high aspect ratio structures is a major driver for broad use and adoption of atomic layer deposition (ALD) processes. ALD is particularly promising for applications coupled to anodic aluminum oxide (AAO) membranes, in which cylindrical nanopores with uniform dimensions (15-300nm dia) and spacing are formed by self-assembly during anodization. In turn these structures form templates useful for creating energy and display devices within the AAO template, or released nanotube or nanowire systems after AAO dissolution, e.g. for nanoparticle-based targeted drug delivery. We have created high-K dielectric nanotubes by HfO2 ALD in AAO templates to investigate the relationship between ALD process parameters and the conformality of the ALD films in the nanopores as a function of nanopore dimensions and aspect ratios. SEM was used to measure pore diameters (40-80nm) before and after the ALD deposition. The HfO2 nanotubes were then released by dissolution of the AAO template and examined via TEM imaging of the nanotubes on standard grids. TEM profiles showed HfO2 nanotubes with lengths 1-2 microns (determined by the AAO template) and having wall thicknesses in the range 3-10 nm which vary with position along the depth of the original AAO nanopores. The AAO templates are attractive both for the applications above and for the ease with which they generate very high aspect ratio nanopores to study ALD conformality, while the nanotube release through AAO template dissolution provides a very simple means to achieve TEM analysis of ALD conformality. These advantages are particularly striking in comparison to requirements for more conventional high aspect ratio devices such as DRAM trench structures, where challenging lithography, dry etching, etc. must be combined with difficult cross-sectional TEM sample preparation to understand and optimize ultrathin conformal device layers.