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A Segmented‐Target Sputtering Process for Growth of Sub‐50 nm Ferroelectric Scandium–Aluminum–Nitride Films with Composition and Stress Tuning
Author(s) -
Rassay Sushant,
Hakim Faysal,
Li Chao,
Forgey Christian,
Choudhary Nitin,
Tabrizian Roozbeh
Publication year - 2021
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.202100087
Subject(s) - materials science , residual stress , ferroelectricity , scandium , crystallinity , nitride , sputtering , thin film , composite material , optoelectronics , metallurgy , nanotechnology , dielectric , layer (electronics)
Harnessing the recently discovered ferroelectricity in scandium aluminum nitride (Sc x Al 1− x N) for the realization of integrated electronic and electromechanical devices requires a low‐temperature growth process that enables versatile control over film thickness, stoichiometric composition, and stress. Herein, a reactive magnetron sputtering process that enables extreme scaling of film thickness and tuning of composition and residual stress is reported on. Highly crystalline Sc x Al 1− x N films with thicknesses of over 25–250 nm with scandium concentrations of over 22–30 at% are sputtered using a segmented target created from scandium and aluminum tiles. The residual stress in the films is widely tuned from highly compressive to tensile using a pressure‐ and gas‐flow‐independent approach based on adjusting the electrical termination of the targets. The crystallinity, texture, and ferroelectric characteristics are measured for Sc x Al 1− x N films with different thicknesses, compositions, and residual stresses. The results highlight the consistent crystallinity and ferroelectric properties despite extreme thickness miniaturization to sub‐50 nm, and the large dependence of the coercive field on the residual stress and Sc concentration.