ScholarWorks@숙명여자대학교

초록

This study investigates the impact of seed layer materials on ferroelectric La-doped (Hf, Zr)O2 (La:HZO) capacitor, designed with back-end-of-line (BEOL) compatibility. The seed layers influence the number and size distribution of HZO nano-crystallites in the as-grown state due to differences in surface passivation and oxidation potential, ultimately leading to variations in the final grain size after post-metallization annealing (PMA). An inverse relationship is observed between the initial number of nano-crystallites and the final grain size, attributed to impingement between growing grains during annealing. These distinct grain growth behaviors drive different phase evolutions in the HZO films, depending on pathways in the phase diagram. While WO3 and ZrO2 seed layers result in undesirable grain size distributions and pathways in the phase diagram leading to inferior electrical performances, the TiO2 seed layer yields intermediate nano-crystallite numbers and sizes, promoting sufficient ferroelectric orthorhombic phase formation. These findings indicate that precise control of HZO nano-crystallite formation through seed layer engineering with careful consideration of phase evolution mechanisms, is essential for continued scaling of HZO film thickness in advanced ferroelectric devices.

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