Study of the electrical and chemical properties of the multistep deposited and two-step (ultraviolet ozone cum rapid thermal) annealed HfO2 gate stack

• Main Authors: Yew, Kwang Sing, Ang, Diing Shenp, Tang, Lei Jun, Pan, Jisheng
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2015
• Subjects: Chemical bonds
• Online Access: https://hdl.handle.net/10356/81294; http://hdl.handle.net/10220/39217
• Institution: Nanyang Technological University

The authors show that the TiN/HfO2/SiOx gate stack, formed via multistep deposition cum two-step anneal [comprising a room-temperature ultraviolet ozone (RTUVO) anneal and a subsequent rapid thermal anneal (RTA) at 420 °C], exhibits more superior electrical characteristics as compared to the gate stacks formed via multistep deposition cum single-step anneal (either RTUVO anneal or 420 °C RTA). The former exhibits more than an order of magnitude smaller gate current density, a 14-fold increase in the time-to-breakdown, and reduced positive oxide trapped charge as compared to the latter. The enhanced performance and reliability are attributed to the improved formation of Hf–O bonds in HfO2, resulting from the efficient incorporation of oxygen atoms facilitated by the thermal activation of the absorbed ozone. The findings provide insights into the improvement mechanism by the two-step anneal method for high-k last integration scheme.