Oxygen‐Scavenging Effects of Added Ti Layer in the TiN Gate of Metal‐Ferroelectric‐Insulator‐Semiconductor Capacitor with Al‐Doped HfO₂ Ferroelectric Film

Abstract

Ti layer inserted in the TiN gate electrode effectively scavenges the oxygen in the low‐k interfacial SiO2 of the metal–ferroelectric–insulator–semiconductor (MFIS) capacitors with the ferroelectric Al‐doped HfO2 (HAO) thin film. The scavenging effect increases remanent polarization (Pr) and reduces coercive voltage (Vc) and capacitance equivalent thickness (CET) of the HAO films, particularly when the MFIS capacitor is annealed at 800 °C. Additionally, frequency dispersion of capacitance characteristics and interface trap density (Dit) calculations reveal that actively‐triggered oxygen‐scavenging effects also reduce defect or trap‐induced degradation. The Ti‐inserted MFIS structure exhibits fatigue‐free endurance and relatively low leakage current characteristics as compared to a structure without the Ti scavenging layer in high annealing temperature conditions required for crystallization of the HAO ferroelectric films.

Perspective on Ferroelectric Devices: Lessons from Interfacial Chemistry

“…These techniques can be categorized as direct or remote scavenging if the scavenging elements are incorporated in or isolated from the high- k layer, respectively. Many studies have attempted to remove the low- k IL in HfO 2 -based FeFETs using scavenging techniques. ,, Lee et al reduced the thickness of the low- k ILs in Al:HfO 2 -based MFIS capacitors using a remote scavenging technique with TiN/Ti/TiN top electrodes. As is evident from the HRTEM image in Figure (a), the top TiN/Ti/TiN electrode decomposes SiO 2 during annealing at 800 °C.…”

Neuromorphic devices based on fluorite‐structured ferroelectrics

“…In contrast, FTJs are less sensitive to trapped charges during the readout process than FeFETs; however, similar reliability issues exist in FTJs based on ferroelectric/dielectric bilayers 191 . Several interfacial engineering methods, such as using a high‐k interlayer such as SiON, AlON, SiN x , ZrO 2 , Al 2 O 3 , or TiO 2 as the interlayer to replace SiO x , utilizing a scavenging layer, and optimizing annealing conditions, have been proposed to overcome these challenges, 27,124,125,169,192–203 and have showed impressive stability 96,99,192,204 . In addition to the properties related to device reliability, other key device performance parameters are scalability, switching speed, and programming energy.…”

“…AlON, SiN x , ZrO 2 , Al 2 O 3 , or TiO 2 as the interlayer to replace SiO x , utilizing a scavenging layer, and optimizing annealing conditions, have been proposed to overcome these challenges, 27,124,125,169,[192][193][194][195][196][197][198][199][200][201][202][203] and have showed impressive stability. 96,99,192,204 In addition to the properties related to device reliability, other key device performance parameters are scalability, switching speed, and programming energy.…”

Oxygen scavenging of HfZrO2-based capacitors for improving ferroelectric properties

“…28,29 Alternatively, the improvement of endurance and retention properties by intentionally forming high- k IL of SiON instead of SiO 2 using a high-temperature nitridation 30,31 and by using an epitaxial SiGe substrate that forms less IL compared to the Si substrate 32 has been reported. Moreover, oxygen scavenging, examined in high- k /metal gate technology to reduce or eliminate IL, was conducted for IL scaling in the MFM structure, 33,34 MFIS structure, 35 and template layer, 36 but the effect on endurance and retention properties of MFIS structure is still unclear.…”