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Improved Al-Via Fill Process Technology for Sub-0.251µm Interconnect
Published online by Cambridge University Press: 10 February 2011
Abstract
In this paper, a simple and improved method for Al via fill is demonstrated. The ALPS (Aluminum Low Pressure Seed) technique was used to deposit a smooth, highly conformal Al seed layer over an all-IMP (ionized metal plasma) Ti/TiN/Ti stack. Subsequent warm Al deposition was carried out in a conventional warm Al chamber. The ALPS method was compared to standard hot Al deposition. Physical SEM characterization and electrical data showed lower via resistances, with better yield for ALPS. No voiding was observed even within unlanded vias. With the ALPS seed layer, the IMP Ti/TiN/Ti liner stack provided a superior wetting surface compared to an IMP Ti-only liner which resulted in voids within unlanded vias. Electrical data obtained for ALPS- and hot Al-deposited Kelvin vias and via chains with various via/metal underlaps were compared with conventional CVD W plugs (using IMP TiN as the glue layer). Both Al fill methods gave lower via resistance compared with W plugs, as expected.
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- Copyright © Materials Research Society 1999
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