Alignment mark recognition, in photolithographic production of multilayer metallizations on wafers, is improved by back etching metal present in the marks to expose mark edges after metal deposition and CMP steps

摘要

Alignment mark recognition improvement, by back etching metal present in the marks to expose mark edges after metal deposition and CMP steps, is new. Improved recognition of alignment marks on wafers during a multilayer metallization operation, which involves producing marks in scored grooves and vias to deeper lying metallizations or active regions by photolithographic structuring of an oxide layer by etching and subsequent metal deposition, followed by CMP wafer planarization and Al metallization, is achieved by back etching metal present in the marks, after the metal deposition and CMP steps, to expose the mark edges. Preferred Features: Back etching is carried out by reactive ion etching (RIE) or inductive coupled plasma (ICP) etching in a Cl2/SF6/NF3 atmosphere containing added O2 and/or N2.