Oxygen enhancement of ion metal plasma (IMP) sputter deposited barrier layers

The present disclosure pertains to our discovery that depositing various film layers in a particular order using a combination of Ion Metal Plasma (IMP) and traditional sputter deposition techniques with specific process conditions results in a barrier layer structure which provides excellent barrier properties and allows for metal/conductor filling of contact sizes down to 0.25 micron and smaller without junction spiking. Specifically, the film layers are deposited on a substrate in the following order: (a) a first layer of a barrier metal (M), deposited by IMP sputter deposition; (b) a second layer of an oxygen-stuffed barrier metal (MOx), an oxygen-stuffed nitride of a barrier metal (MNOx), or a combination thereof; (c) a third layer of a nitride of a barrier metal (MNx), deposited by IMP sputter deposition of the barrier metal in the presence of nitrogen; and (d) a fourth, wetting layer of a barrier metal, deposited by traditional sputter deposition. The first layer of barrier metal can optionally be annealed to form a silicide of the barrier metal (MSi2) in order to reduce contact resistance and interdiffusion of the silicon and metal/conductor which may result from overetching of contacts. An additional layer of barrier metal can optionally be deposited between the second oxygen-stuffed layer and the third barrier metal nitride layer in order to further improve the barrier properties of the barrier layer structure and to provide for better metal/conductor fill. A thin layer of metal/conductor may be deposited on the walls of the contact via by ""long throw"" sputter deposition prior to filling the via with metal/conductor in order to provide more uniform fill. The optimum process conditions for sputter deposition of the barrier layer structure of the invention are disclosed herein.