Improved Performance of MoS } Negative-Capacitance Field-Effect Transistors With Hf -\textit} La } O } N } as Gate Dielectric by Optimizing La Content and Anneal Temperature Plus NH } -Plasma Treatment

• Published in: IEEE transactions on electron devices pp. 1 - 7
• Main Authors: Tian, Yuying, Liu, Lu, Jiang, Weichao, Xu, Jing-Ping
• Format: Journal Article
• Language: English
• Published: IEEE 23.08.2023
• Subjects: Annealing; Hafnium; Hafnium oxide; hysteresis; Lanthanum (La)-doped hafnium-based oxynitride (HfLaON); Logic gates; molybdenum disulfide (MoS<inline-formula xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <tex-math notation="LaTeX"> _{\text{2}}</tex-math> </inline-formula>); negative-capacitance (NC) field-effect transistors (NCFETs); Silicon; subthreshold swing (SS); Three-dimensional displays; Transistors
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2023.3299914

A negative-capacitance field-effect transistor (NCFET) is fabricated by co-sputtering lanthanum (La)-doped hafnium-based oxynitride (HfLaON) as ferroelectric gate dielectric and using MoS<inline-formula> <tex-math notation="LaTeX">_\text{2}</tex-math> </inline-formula> as the channel. The ferroelectricity of the HfLaON thin films is verified through microanalyses on the thin film and electrical characterization. Effects of La content and anneal temperature on the ferroelectricity of the thin films and electrical properties of MoS<inline-formula> <tex-math notation="LaTeX">_\text{2}</tex-math> </inline-formula> NCFETs are investigated. It is found that a low subthreshold swing (SS <inline-formula> <tex-math notation="LaTeX">=</tex-math> </inline-formula> 44.5 mV/dec) and small hysteresis (94.4 mV) can be achieved when the La content and anneal temperature are 10% and 800 <inline-formula> <tex-math notation="LaTeX">^{\circ}</tex-math> </inline-formula>C respectively, due to the formation of more orthorhombic phases and thus enhanced ferroelectricity. Further, a remote NH<inline-formula> <tex-math notation="LaTeX">_\text{3}</tex-math> </inline-formula>-plasma treatment is used to improve the quality of the HfLaON thin film and electrical properties of the devices, which results in a lower SS (38.2 mV/dec), a smaller hysteresis (54.7 mV), and a higher ON/OFF current ratio (1.57 <inline-formula> <tex-math notation="LaTeX">\times</tex-math> </inline-formula> 10<inline-formula> <tex-math notation="LaTeX">^{\text{6}}</tex-math> </inline-formula>) than that of the device without NH<inline-formula> <tex-math notation="LaTeX">_\text{3}</tex-math> </inline-formula>-plasma treatment. The involved mechanisms lie in the fact the N incorporation into the thin film could improve the qualities of the thin film and its interfaces by passivating oxygen vacancies and dangling bonds, and reducing its surface roughness, which enhances the ferroelectricity of the thin films and thus negative-capacitance (NC) effect of NCFETs.