Sputter deposition collimated

Z. Lin, T.S. Cale, Flux distribution and deposition profiles from hexagonal collimators during sputter deposition, J. Vac. Sci. Technol. 13(4) (1995) 2183. 

Aluminum, the most common material used for contacts, is easy to use, has low resistivity, and reduces surface Si02 to form interfacial metal-oxide bonds that promote adhesion to the substrate. However, as designs reach submicrometer dimensions, aluminum, Al, has been found to be a poor choice for metallization of contacts and via holes. Al has relatively poor step coverage, which is nonuniform layer thickness when deposited over right-angled geometric features. This leads to keyhole void formation when spaces between features are smaller than 0.7 p.m. New collimated sputtering techniques can extend the lower limit of Al use to 0.5-p.m appHcations. 

Sputtering from a large-area source produces a vapor flux that has a wide distribution of angle-of-incidence at the substrate surface. To produce a more normal incidence pattern, the sputtered atoms can be colhmated using a honeycomb-shaped baffle between the target and the substrate. This collimation tends to decrease the tendency of the deposition to produce a columnar morphology in the deposited him and enhances the hlling of vias in semiconductor device fabrication. 

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