Effect of post metallization annealing on structural and electrical properties of Ge metal-oxide-semiconductor (MOS) capacitors with Pt/HfO 2 gate stack

• Published in: Microelectronic engineering Vol. 89; pp. 76 - 79
• Main Authors: Jagadeesh Chandra, S.V., Kim, Jin-Sung, Moon, Kyung-Won, Choi, Chel-Jong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2012
• Subjects: Effective work function; EOT; Fermi level pinning; HfO 2; Metal gate; MOS; MOS; EOT; HfO 2; Effective work function; Fermi level pinning; Metal gate
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2011.03.156

[Display omitted] ► O 2 post metallization annealing leads to the improvement of HfO 2 interfacial quality. ► The incorporation of Ge atoms in HfO 2 film causes the decrease in the accumulation capacitance. ► Negative charge on Ge induced by annealing at 600 °C leads to the increase in Φ m,eff of Pt electrode. We fabricated Ge metal-oxide-semiconductor (MOS) capacitors with Pt/HfO 2 gate stack and demonstrated the effects of post metallization annealing on their structural and electrical properties. Post metallization annealing was carried out at the temperatures of 500 and 600 °C for 30 min in oxygen (O 2) ambient. Post metallization annealing at both temperatures led to the reduction of the interface traps density ( D it) with a decrease in accumulation capacitance. By considering the presence of interfacial layer (IL) in-between HfO 2 and Ge, the effective work function ( Φ m,eff) values of Pt gate electrode after annealing at 500 and 600 °C, extracted from the relations of equivalent oxide thickness (EOT) versus flatband voltages ( V FB), were determined to be ∼4.05 and ∼5.43 eV, respectively. The presence of positive charge at the interface between HfO 2 and IL produced by the formation of oxygen-rich HfO 2/IL interface resulted in the minimization of Fermi level pinning in Ge, which could be responsible for relatively high Φ m,eff value of Pt gate electrode in Ge MOS capacitor with O 2 post metallization annealing at 600 °C.