Method for making multilayer connection structure

摘要

A method provides electrical connections to a stack of contact levels of an interconnect region for a 3-D stacked IC device. Each contact level comprises conductive and insulation layers. A portion of any upper layer is removed to expose a first contact level and create contact openings for each contact level. A set of N masks is used to etch the contact openings up to and including 2N contact levels. Each mask is used to etch effectively half of the contact openings. When N is 3, a first mask etches one contact level, a second mask etches two contact levels, and a third mask etches four contact levels. A dielectric layer may be formed on the sidewalls of the contact openings. Electrical conductors may be formed through the contact openings with the dielectric layers electrically insulating the electrical conductors from the sidewalls.