Method for making a new metal-insulator-metal (mim) capacitor structure in copper-cmos circuits using a pad protect layer

Abstract

This MIM structure provides metal capacitors with high figure of merit Q (X /R) and does not require additional masks and metal layers. A copper capacitor bottom metal (CBM) electrode is formed, while concurrently forming the pad contacts and level of copper interconnections by the damascene process. An insulating (Si N ) metal protect layer is formed on the copper and a capacitor interelectrode dielectric layer is formed. A metal protecting buffer protects the thin interelectrode layer, and openings are etched to pad contacts and interconnecting lines. A TiN/AlCu/TiN metal layer is deposited and patterned to form the capacitor top metal (CTM) electrodes, the next level of interconnections, and to provide a pad protect layer on the copper pad contacts. The thick TiN/AlCu/TiN CTM electrode reduces the capacitor series resistance and improves the capacitor figure of merit Q, while the pad protect layer protects the copper from corrosion.