REACTIVE-ION-ETCH-COMPATIBLE METALLIZATION FOR PARTIALLY COVERED CONTACT APPLICATIONS

Abstract Development of a metallization compatible with both partially covered contacts and reactive ion etch (RIE) pattern definition requires an etch stop and a metal structure that minimizes post-RIE residue. Self-aligned NiSi provides an etch stop layer for RIE using chlorinated gases and its reliability as a contact material has been demostrated in contact migration studies. Line-spacing-dependent residues have been observed with spaces more than 10 μm wide, while spaces less than 10 μm wide etch cleanly. Residue-free etching has been obtained using a pure aluminum layer below the Al-Cu layer in the metallization. Residue-free etching was observed only when as-deposited films were etched. Heat treatments of Al-Cu-containing metallizations prior to etching can cause post-RIE residues.