| abstract |
An aluminum sputtering process, particularly useful for filling vias andncontacts of high aspect ratios formed through a dielectric layer and also usefulnfor forming interconnects that are highly resistant to electromigration. A liner ornbarrier layer (150) is first deposited by a high-density plasma (HDP) physicalnvapor deposition (PVD, also called sputtering) process, such as is done with anninductively coupled plasma. If a contact (140) is connected at its bottom to ansilicon element (144), the first sublayer (160) of the liner layer is a Ti layer,nwhich is silicided to the silicon substrate. The second sublayer (162) comprisesnTiN, which not only acts as a barrier against the migration of undesirablencomponents into the underlying silicon but also when deposited with an HDPnprocess and biased wafer forms a dense, smooth crystal structure. The thirdnsublayer (164) comprises Ti and preferably is graded from TiN to Ti. Over thenliner layer, an aluminum layer (156) is deposited in a standard, non-HDPnprocess. The liner layer allows the hottest part of the aluminum deposition to benperformed at a relatively low temperature between 320 and 500°C, preferablynbetween 350 and 420°C, while still filling narrow plug holes, and the TiN doesnnot need to be annealed to form an effective barrier against diffusion into thensilicon. A horizontal interconnect formed by the inventive process is resistant tonelectromigration. |