Lift-Off Process For CrCuAu Metallurgy
Original Publication Date: 1979-Jun-01
Included in the Prior Art Database: 2005-Feb-20
Current processes for CrCuAu terminal pad metallurgy 3, as in Fig. 4, have involved evaporation through a metal mask to internal AlCu device metallization 4. Since the mask is normally made of molybdenum, there is a fundamental expansivity difference between it and the Si substrate 5. Shifts in the relative position of the mask openings during the evaporation can produce "halos" around the CrCuAu pads, which result in surface leakage and shorting problems between pads. Metal masks also limit the size (diameter) of the CrCuAu pad; the size of the hole etched in the Mo mask cannot be less than the thickness of the Mo mask. This problem is further complicated by the necessary increase in mask size and thickness as the wafer size increases.