| abstract |
A method was achieved for forming a multilayer passivation layer comprised of a silicon oxide/silicon nitride/silicon oxide/silicon nitride by depositing the layers consecutively in a single PECVD system. The method consists of depositing a first SiO2 layer that serves as a stress-release layer, a thin Si3N4 layer that serves as a buffer layer that minimizes cracking and as a passivation layer that prevents mobile alkaline ion penetration, a thin second SiO2 layer to fill and seal any remaining cracks and pinholes in the first Si3N4 layer, and a main Si3N4 passivation layer that prevents water and/or other corrosive chemicals from attacking the metal. Since this multilayer passivation layer can be deposited essentially pinhole-free to a thickness that is less than the prior art's passivation layer of 8000 Angstroms needed to prevent pinholes, it can be used on 0.38 to 0.25 um DRAM technology, which eliminates voids that could otherwise trap photoresist which can later cause corrosion of the metal lines. |