N Penetration Enhances Vacancy Filling, Al/Sc-N Bonding, and Ferroelectric Properties in AlScN Films

We demonstrate, for the first time, that nitrogen(N) penetration into AlScN films significantly enhances ferroelectric performance by suppressing N vacancies and increasing grain size. This is achieved by introducing N from a TiN bottom electrode. As a result, we achieve a remnant polarization (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub>) of 150 μC/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, a notable reduction in leakage current, and a high breakdown-to-coercive field ratio (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BD</sub>/<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub>) of 1.85. Material analysis shows that N from the TiN electrode fills N vacancies, suppresses oxidation, and improves the crystalline quality of AlScN, the AlScN/TiN interface, and overall ferroelectric performance. This simple yet effective N treatment strategy advances AlScN material properties and enables next-generation ferroelectric electronics.