Thin films with nanometer-scale pillar microstructure

Thin films possessing microstructure composed of isolated vertical pillars were deposited by glancing angle deposition (GLAD) without the need for subsequent etch processing. The GLAD technique uses substrate rotation and oblique angle flux incidence to deposit a porous columnar thin film with engineered microstructures. Thin films with a pillar microstructure were fabricated from a variety of metals, metal oxides and fluorides, and semiconductors. The rate and incident angle of vapor flux, as well as the substrate rotation speed during deposition, were found to critically affect pillar microstructure. Thin films with pillar diameters and densities as low as 30 nm and 3 pillars per μm², respectively, were deposited. The low stress, high surface area, and porous nature of these films suggests use of pillar microstructure films in optical, chemical, biological, mechanical, magnetic, and electrical applications.