title: TEM-based metrology for HfO2 layers and nanotubes formed in anodic aluminum oxide nanopore structures.
abstract: Nanotubes are fabricated by atomic layer deposition (ALD) into nanopore arrays created by anodic aluminum oxide (AAO). A transmission electron microscopy (TEM) methodology is developed and applied to quantify the ALD conformality in the nanopores (thickness as a function of depth), and the results are compared to existing models for ALD conformality. ALD HfO2 nanotubes formed in AAO templates are released by dissolution of the Al2O3, transferred to a grid, and imaged by TEM. An algorithm is devised to automate the quantification of nanotube wall thickness as a function of position along the central axis of the nanotube, by using a cylindrical model for the nanotube. Diffusion-limited depletion occurs in the lower portion of the nanotubes and is characterized by a linear slope of decreasing thickness. Experimentally recorded slopes match well with two simple models of ALD within nanopores presented in the literature. The TEM analysis technique provides a method for the rapid analysis of such nanostructures in general, and is also a means to efficiently quantify ALD profiles in nanostructures for a variety of nanodevice applications.
authors.affiliation: Department of Materials Science and Engineering and Institute for Systems Research, University of Maryland, 2145 A. V. Williams Building, College Park, MD 20742-3285, USA.
authors.forename: Israel
authors.initials: I
authors.lastname: Perez
authors.forename: Erin
authors.initials: E
authors.lastname: Robertson
authors.forename: Parag
authors.initials: P
authors.lastname: Banerjee
authors.forename: Laurent
authors.initials: L
authors.lastname: Henn-Lecordier
authors.forename: Sang Jun
authors.initials: SJ
authors.lastname: Son
authors.forename: Sang Bok
authors.initials: SB
authors.lastname: Lee
authors.forename: Gary W
authors.initials: GW
authors.lastname: Rubloff
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D006195:Hafnium / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D036103:Nanotechnology; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: D000537:Aluminum Oxide; D006195:Hafnium