Improved Thermo Mechanical Mask Evaporation Process
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
Two new techniques are reported for improving the quality of evaporated metallurgy by controlling the heat imparted to a metal mask during the evaporation process. The high temperature measured at the mask/wafer interface during deposition causes mask bowing and shifting. This results in a yield loss due to misalignment of the metal deposited on the wafer. To avoid high mask temperatures, a high temperature polyimide film material patterned to match the metal mask is aligned over and placed in contact with the mask so as to intercept evaporant that would normally strike the metal mask directly. The thin insulator facing film keeps the metal mask cooler, is patterned using standard photolithographic techniques and reduces the deleterious thermo mechanical effects on the mask.