International Business Machines Corporation
Method of forming a BEOL interconnect structure using a subtractive metal via first process

Abstract:

A method of forming a BEOL interconnect structure having improved resistance-capacitance is provided in which a via metal layer is created by a first metallization process and thereafter shrunk by a subtractive etch; these steps relax the critical dimension, ensure a via straight profile, avoid via chamfering and bowing, and maximize metal volume. Top trench metallization is then performed above the via metal layer; this step eliminates reactive ion etch lag and ensures no metallization void issues.