Al/Cu METAL SKIRT REMOVAL PROCESS
Original Publication Date: 1985-Jan-01
Included in the Prior Art Database: 2005-Feb-18
This process provides a method of removing the pad-to-wafer skirt formed during Al/Cu metal deposition. The undesirable skirt causes diffusion problems and device failures during subsequent process steps. An undercut photoresist image 1 is created by a conventional multilayer process to provide a lift-off structure for a metal line. The metal 2 is directionally deposited in a vacuum chamber, the space in the photoresist becomes the line, and excess metal is removed when the photoresist is dissolved in solvents. If Al/Cu alloy is deposited as the first metal, directly upon substrates such as platinum silicide, diffusion of Al into the silicide can cause device failure when wafers are heated. (After the second metal deposition is connected to the first metal, the wafer is sintered to insure low contact resistance between them.