Ultrasonic Removal of Dry Seeding
Original Publication Date: 1985-Oct-01
Included in the Prior Art Database: 2005-Feb-19
In a dry seeding process, an insulative substrate is drilled and has circuit configurations formed in a coating of laminated film photoresist. The substrate is then dry-seeded for subsequent plating by sputtering metal over the entire surface. The metal seed is removed easily from the smooth photoresist surface by scrubbing. However, the trench- side walls retain the seed after scrubbing. The trench sidewalls are cleaned by scanning the substrate surface with an ultrasonic transducer to detach the adhering seed but not damage the seed on the substrate surface. Conductor build-up during subsequent plating then occurs only from the seeded bottoms of the trenches and drilled holes, and not concurrently from the trench sidewalls.