Work

Fabrication of Ultrathin Ferroelectric Al0.7Sc0.3N Films under Complementary‐Metal‐Oxide‐Semiconductor Compatible Conditions by using HfN0.4 Electrode

Year: 2024

Type: article

Abstract: Aluminum scandium nitride (AlScN) has emerged as a promising candidate for next‐generation ferroelectric memories, offering a much higher remanent charge density than other materials with a stable ferroelectric phase. However, the inherently high coercive field requires a substantial decrease in film thickness to lower the operating voltage. Significant leakage currents present a severe challenge during the thickness scaling, especially when maintaining compatibility with complementary‐metal‐oxide‐semiconductor (CMOS) fabrication standards. This study adopts a HfN0.4 bottom electrode, which minimizes lattice mismatch with Al0.7Sc0.3N (ASN), forming a coherent bottom interface that effectively reduces leakage currents even at thickness < 5 nm. CMOS‐compatible HfN0.4/ASN/TiN stack, deposited without vacuum break between each layer, demonstrates exceptional scalability, confirming the ferroelectricity of ASN films at thicknesses down to 3 nm. The coercive voltage is decreased to 4.35 V, significantly advancing low‐voltage AlScN devices that align with CMOS standards.

Source: Advanced Materials

DOI: 10.1002/adma.202413295