Method for forming local interconnects using chlorine bearing agents

A method for etching titanium nitride local interconnects is disclosed. A layer of titanium nitride is formed as a by-product of the formation of titanium silicide by direct reaction; this layer of titanium nitride is present over the titanium silicide layer, as well as over insulators such as oxide. A plasma etch using CCl4 as the etchant is used to etch the titanium nitride anisotropically, and selectively relative to the titanium silicide due to the passivation of the titanium silicide surface by the carbon atoms of the CCl4. Excess chlorine concentration may be reduced, further reducing the undesired etching of the titanium silicide, by providing a consumable power electrode, or by introducing chlorine scavenger gases in the reactor. The plasma may be ignited by exposing the gases to a mercury/argon light source, photodetaching electrons from the anions in the gas.