Materials properties of hafnium and zirconium silicates: Metal interdiffusion and dopant penetration studies.

Hafnium and Zirconium based gate dielectrics are considered potential candidates to replace SiO2 or SiON as the gate dielectric in CMOS processing. Furthermore, the addition of nitrogen into this pseudo-binary alloy has been shown to improve their thermal stability, electrical properties, and reduce dopant penetration. Because CMOS processing requires high temperature anneals (up to 1050 °C), it is important to understand the diffusion properties of any metal associated with the gate dielectric in silicon at these temperatures. In addition, dopant penetration from the doped polysilicon gate into the Si channel at these temperatures must also be studied. Impurity outdiffusion (Hf, Zr) from the dielectric, or dopant (B, As, P) penetration through the dielectric into the channel region would likely result in deleterious effects upon the carrier mobility. In this dissertation extensive thermal stability studies of alternate gate dielectric candidates ZrSixOy and HfSixOy are presented. Dopant penetration studies from doped-polysilicon through HfSixOy and HfSixOyNz are also presented. Rutherford backscattering spectroscopy (RBS), heavy ion RBS (HI-RBS), x-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM), and time of flight and dynamic secondary ion mass spectroscopy (ToF-SIMS, D-SIMS) methods were used to characterize these materials. The dopant diffusivity is calculated by modeling of the dopant profiles in the Si substrate. In this disseration is reported that Hf silicate films are more stable than Zr silicate films, from the metal interdiffusion point of view. On the other hand, dopant (B, As, and P) penetration is observed for HfSixOy films. However, the addition of nitrogen to the Hf - Si - O systems improves the dopant penetration properties of the resulting HfSixOyNz films.

Grantor dc:publisher

University of North Texas

Year dc:date

2002

Author dc:creator

• Quevedo-Lopez, Manuel Angel

Contributors dc:contributor

• Wallace, Robert M.
• Gnade, Bruce
• Colombo, Luigi
• Bouanani, Mohamed El
• Kelber, Jeffry A.
• Mendoza, Oscar

• Hafnium.
• Zirconium.
• Silicates.
• Dielectrics.
• HfSixOy
• CMOS processing
• thermal stability
• dopant penetration

Statement dc:rights

• Public
• Copyright
• Quevedo-Lopez, Manuel Angel
• Copyright is held by the author, unless otherwise noted. All rights reserved.

Language dc:language

English

Identifier

oclc: 50802350
https://digital.library.unt.edu/ark:/67531/metadc3221/
ark: ark:/67531/metadc3221

OAI identifier oai:identifier

info:ark/67531/metadc3221