HfO2 gate dielectric on Ge (111) with ultrathin nitride interfacial layer formed by rapid thermal NH3 treatment

• Published in: Applied surface science Vol. 364; pp. 747 - 751
• Main Authors: Agrawal, Khushabu S., Patil, Vilas S., Khairnar, Anil G., Mahajan, Ashok M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 28-02-2016
• Subjects: Annealing; Current conduction mechanism; Deposition; Gates; Germanium; Hafnium oxide; HfO2; MOS devices; Nitrides; Passivation; PEALD; X-ray photoelectron spectroscopy; XPS; XPS; PEALD; HfO2; Current conduction mechanism; Passivation
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2015.12.218

•The GeON/HfO2 gate stack is formed on germanium (111) substrate.•The rapid thermal nitridation was carried out by using NH3.•The GeON forms the stable interface between high-k and Gesubstrate.•The results show the improvement in k value and EOT due to NH3 pre deposition annealing.•The effect of post metallization annealing was studied on different parameters of Ge MOS devices.
Interfacial properties of the ALD deposited HfO2 over the surface nitrided germanium substrate have been studied. The formation of GeON (∼1.7nm) was confirmed by X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron spectroscopy (HRTEM) over the germanium surface. The effect of post deposition annealing temperature was investigated to study the interfacial and electrical properties of hafnium oxide/germanium oxynitride gate stacks. The high-k MOS devices with ultrathin GeON layer shows the good electrical characteristics including higher k value ∼18, smaller equivalent oxide thickness (EOT) around 1.5nm and smaller hysteresis value less than 170mV. The Qeff and Dit values are somewhat greater due to the (111) orientation of the germanium and may be due to the presence of nitrogen at the interface. The Fowler–Northeim (FN) tunneling of Ge MOS devices has been studied. The barrier height ΦB extracted from the plot is ∼1eV.