AVS 53rd International Symposium
    Electronic Materials and Processing Friday Sessions
       Session EM+TF-FrM

Invited Paper EM+TF-FrM3
Materials Challenges for High Permittivity Gate Dielectrics and Metal Gate Electrodes

Friday, November 17, 2006, 8:40 am, Room 2003

Session: High-k Dielectric & Multi-Functional Oxide Growth & Processing
Presenter: J.K. Schaeffer, Freescale Semiconductor, Inc.
Authors: J.K. Schaeffer, Freescale Semiconductor, Inc.
D. Gilmer, Freescale Semiconductor, Inc.
S. Samavedam, Freescale Semiconductor, Inc.
M. Raymond, Freescale Semiconductor, Inc.
D.H. Triyoso, Freescale Semiconductor, Inc.
R.I. Hegde, Freescale Semiconductor, Inc.
M. Stoker, Freescale Semiconductor, Inc.
S. Kalpat, Freescale Semiconductor, Inc.
C. Capasso, Freescale Semiconductor, Inc.
B. Taylor, Freescale Semiconductor, Inc.
P.J. Tobin, Freescale Semiconductor, Inc.
B.E. White, Freescale Semiconductor, Inc.
S. Walsh, The Ohio State University
L. Fang, The Ohio State University
L.J. Brillson, The Ohio State University
Correspondent: Click to Email
This talk will review recent advances and remaining challenges associated with high-k gate dielectrics and metal gate electrodes with a specific focus on the fundamental materials properties responsible for critical device characteristics. Recent reports have shown that alloying ZrO@sub 2@ into HfO@sub 2@ improves device reliability and effective oxide thickness (EOT) scaling. This talk will review the structural and electrical properties of Hf@sub x@Zr@sub 1-x@O@sub 2@ films that impact EOT and device reliability. Next, to better understand the nature of the metal/HfO@sub 2@ interface, the previously established empirical relationship between the mean electronegativity and effective work function developed for Schottky contacts has been applied to multi-element electrode materials on hafnium dioxide gate dielectrics. Our data show good agreement with the pre-existing framework established for metal/insulator contacts, and illustrates the important role that sub-lattice elements such as N and C can have on effective work-function. This understanding helped lead to the development of tantalum carbide as a thermally stable NMOS gate electrode candidate. Finally, many device properties result from the electrical and chemical interactions between the various gate stack layers which can lead to differences in EOT growth, increased dielectric leakage, fixed charge, and changes in effective work function. The selection of the gate metal can have a pronounced impact on these properties. Such interactions are likely responsible for the difficulty in manufacturing devices with low PMOS device threshold voltages and scaled EOT on silicon substrates. Recent experiments are now providing new insights into the origins of this problem.