Periodic submicrometer structures by sputtering

It is known that glancing angle deposition (GLAD) utilizing extreme self-shadowing during film growth can produce periodic microstructures on a predefined seed layer using electron-beam evaporation. This deposition process has been applied to the fabrication of periodic arrays of magnetic pillars and has possible applications in optical devices. Critical to the production of these microstructures is adherence to a narrow angular flux distribution centered at an oblique incidence angle, and optimizing the seed pattern for the desired film characteristics. In this article, a low-pressure, long-throw collimated GLAD sputter deposition has been used to fabricate submicrometer scale periodic pillar and quasihelical microstructures over a range of seed separations (e.g., 150, 300, 600, 900, and 1200 mn) and deposition angles (82.5 degrees and 86 degrees with respect to the substrate normal). We have found that for fixed deposition parameters, periodic quasihelical growth degenerates into pillars as the seed separation increases, and that the transitional region over which this degeneration occurs shifts to high seed separations with increasing flux incidence angles. This and other growth trends are also observed and described using the three-dimensional (3D) ballistic simulator, 3D-FILMS, which has proven to be successful in simulating the growth of aperiodic and periodic GLAD films. The use of sputtering for periodic GLAD simplifies the process control, and should enable deposition of a broader range of materials for diverse applications including magnetics, optics, and sensors. (C) 2001 American Vacuum Society.