Importance

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Abstract

An aluminum sputtering process, particularly useful for filling vias and contacts of high aspect ratios formed through a dielectric layer and also usefull for forming interconnects that are highly resistant to electromigration. A liner or barrier layer is first deposited by a high-density plasma (HDP) physical vapor deposition (PVD, also called sputtering) process, such as is done with an inductively coupled plasma. If a contact is connected at its bottom to a silicon element, the first sublayer of the liner layer is a Ti layer, which is silicided to the silicon substrate. The second sublayer comprises TiN, which not only acts as a barrier against the migration of undesirable components into the underlying silicon but also when deposited with an HDP process and biased wafer forms a dense, smooth crystal structure. The third sublayer comprises Ti and preferably is graded from TiN to Ti. Over the liner layer, an aluminum layer is deposited in a standard, non-HDP process. The liner layer allows the hottest part of the aluminum deposition to be performed at a relatively low temperature between 320 and 500.degree. C., preferably between 350 and 420.degree. C., while still filling narrow plug holes, and the TiN does not need to be annealed to form an effective barrier against diffusion into the silicon. A horizontal interconnect formed by the inventive process is resistant to electromigration.

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First Claim