Measurement of Mobile Ion Contamination in Multilayer Metalization by Triangular Voltage Sweep

Abstract

Advanced complementary metal oxide semiconductor and technologies with complex multilayer metallization (MLM) are increasingly susceptible to mobile ion contamination. The potential of the triangular voltage sweep method (TVS) to provide a useful tool for quantifying mobile ion contamination in product‐like MLM structures was investigated. Sodium was introduced by ion implantation over a practical concentration range into various MLM structures and the resulting concentration was determined by TVS and secondary ion mass spectroscopy (SIMS). Excellent agreement was seen between TVS, SIMS, and implant dose, establishing TVS as a practical tool for monitoring mobile ion contamination in MLM structures. A good correlation between TVS and SIMS was observed not only for implanted sodium but also for contamination introduced by sodium containing solutions, a route more representative of MLM processing. Increased sodium incorporation was observed with the presence of doped oxide under metal‐1. Finally, sodium incorporation was shown to depend directly on the length of metal edge present in the capacitor structure. This suggests that evaluation of simple area capacitors results in an underestimate of mobile ion contamination in circuits.