TiW is used as a barrier to interdiffusion between aluminum or aluminum copper thin films (used as interconnections in integrated circuits) and silicon or PtSi contacts, thereby preventing junction short circuits. One method of defining VLSI interconnection patterns is by a lift-off technique. A stencil is defined, and after evaporation, the unwanted metal is removed with the stencil, leaving the interconnection metallization. However, TiW is most practically deposited by sputtering, which is not compatible with this method. If TiW were sputtered through a lift-off mask, the pattern would have sloped walls, and coverage of the walls of the lift-off stencil is a potential problem. A more practical process for the formation of patterns in TiW is subtractive etching, following lift-off formation of the aluminum or aluminum copper on top of a blanket layer of TiW. To insure the absence of undercutting, reactive ion etching (RIE) is used to etch the TiW.