US Patent 7700474 Barrier deposition using ionized physical vapor deposition (iPVD)

An iPVD system uses a high density inductively coupled plasma (ICP) at high pressure of at least 50 mTorr to deposit uniform ultra-thin layer of a tantalum nitride material barrier material onto the sidewalls of high aspect ratio nano-size features on semiconductor substrates, preferably less than 2 nm thick with less than 4 nm in the field areas. The process includes depositing an ultra-thin TaN barrier layer having a high nitrogen concentration that produces high resistivity, preferably at least 1000 micro-ohm-cm. The ultra-thin TaN film is deposited by a low deposition rate process of less than 20 nm/minute, preferably 2-10 nm/min, to produce the high N/Ta ratio layer without nitriding the tantalum target. The layer provides a barrier to copper (Cu) diffusion and a high etch resistant etch-stop layer for subsequent deposition-etch processes.