Siemens Aktiengesellschaft

Guenther Roeska

Josef Winnerl

Franz Neppl

Peter Kuecher

For self-aligned manufacture of contacts referred to as vias between interconnects that are contained in wiring levels arranged above one another in an integrated circuit, a pillar technique is employed where the contacts are produced before the deposition of an inter-metal dielectric to produce the pillar, a layer structure is produced that contains at least one metal layer for the lower wiring level and at least one conductive layer for the contacts. The longitudinal expanse of the contact is defined by a mask that reliably overlaps the desired width of the lower interconnect. The transversal expanse of the contact is defined by the mask needed for producing the lower interconnect. The contacts and the lower interconnects are produced by step-by-step etching.

Method for self-aligned manufacture of contacts between interconnects

To improve the planarization and reliability of low-impedance aluminum metallizations, a substrate provided with a titanium/titanium nitride double layer diffusion barrier layer and having a contact hole is provided or, respectively, filled with an aluminum/silicon alloy sandwich structure composed of a sequence of n aluminum/silicon layers having n-1 intermediate layers of titanium applied thereon, whereby the layer thickness ratio of the titanium intermediate layers to the overall layer thickness d of the metallization behaves like 1:10. The multisandwich metallization manufactured in this way is used in VLSI circuits and, given the same specific resistance achieves a life expectancy that is 10 through 100 times higher than that of the aluminum/silicon/titanium alloys that are otherwise standard.

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Holzkirchen, Germany

Guenther Roeska