Study of the electrical and chemical properties of the multistep deposited and two-step (ultraviolet ozone cum rapid thermal) annealed HfO2 gate stack
Yew, Kwang Sing
Ang, Diing Shenp
Tang, Lei Jun
Date of Issue2015
School of Electrical and Electronic Engineering
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.
Journal of Vacuum Science and Technology B
© 2015 American Vacuum Society. This paper was published in Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena and is made available as an electronic reprint (preprint) with permission of American Vacuum Society. The published version is available at: [http://dx.doi.org/10.1116/1.4936893]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.