Chip To Substrate Interconnection
Original Publication Date: 1981-Oct-01
Included in the Prior Art Database: 2005-Feb-12
The present process for the fabrication of final chip metallization (Al) deposition, sputtered quartz deposition, terminal via hole etching, ball limiting metallurgy (Cr-Cu-Au) deposition, and solder (Pb-Sn) deposition is shown in the attached diagram. To homogenize the solder, the reflow of the solder is effected by subjecting the wafer to heat treatment at 350 Degrees C. The new process described herein consists of final chip metallization (Al) deposition, ball limiting metallurgy (Cr-Cu-Au) deposition, solder (Pb-Sn) deposition, polyimide application, etching with trimethylammonium hydroxide for a few seconds to remove polyimide from the solder, and heating in stages up to 325 Degrees C in a controlled ambient to affect polyimide cure and solder homogenization in a single operation.