Wafer-level method for fine-pitch, high aspect ratio chip interconnect

摘要

A metal structure for an integrated circuit having a plurality of contact pads and a patterned metallization protected by an overcoat layer. The structure comprises a plurality of windows in the overcoat, selectively exposing the chip metallization, wherein the windows are spaced apart by less than 150 m center to center. A metal column is positioned on each of the windows; the preferred metal is copper; the column has a height-to-width aspect ratio larger than 1.25 and an upper surface wettable by re-flowable metal. The preferred column height-to-width aspect ratio is between 2.0 and 4.0, operable to absorb thermomechanical stress. A cap of a re-flowable metal is positioned on each of the columns. The metal structure is used for attaching the IC chip to an external part.