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Oxidation and Gate Dielectrics
Published in Robert Doering, Yoshio Nishi, Handbook of Semiconductor Manufacturing Technology, 2017
C. Rinn Cleavelin, Luigi Colombo, Hiro Niimi, Sylvia Pas, Eric M. Vogel
Hafnium-based gate dielectrics have been deposited mostly by physical vapor deposition (PVD), chemical vapor deposition (CVD), and atomic layer deposition (ALD). Physical vapor deposition has been successfully used to perform the initial pioneering deposition of hafnium silicon oxide (HfSiO) [171] and hafnium silicon oxynitride (HfSiON) [155,166,172]. The initial work performed using PVD HfSiON created the critical data that formed the basis for the direction; the industry has taken on high-k gate dielectrics over the last few years. Today the hafnium-based compounds are now being deposited by ALD and CVD, because of among other reasons compositional control and future potential conformality requirements. Atomic layer deposition has been successfully used to deposit HfO2 using hafnium tetrachloride (HfCl4) [173], and more recently ALD has also been used to deposit HfSiO using metal organic precursors such as tetrakis ethylmethylamido silicon (TEMASi) and tetrakis ethylmethylamido hafnium (TEMAHf) [174]. Chemical vapor deposition processes, on the other hand have used predominantly metal organic precursors such as a combination of tetrakis ethylamido hafnium (TDEAHf) and tetrakis methylamido silicon (TDMAS) [175], and of hafnium (IV) tert-butoxide (HTB) and tetraethoxysilane (TEOS) [176] or disilane (Si2H6). These precursors have been selected after significant investigations that were targeted at minimizing SiO2 interfacial growth during deposition, composition control, particle performance, and device property optimization to name a few.
Extraction and Separation of Zirconium(IV) and Hafnium(IV) from Chloride Media Using Magnetic Resin with Phosphoric Acid Functionality
Published in Journal of Dispersion Science and Technology, 2011
A. M. Donia, A. A. Atia, A. M. Daher, E. A. Elshehy
Stock solution of 1 × 10−2 M of zirconium oxychloride (ZrOCl2·8H2O) and hafnium tetrachloride (HfCl4) was prepared. These solutions must be freshly prepared due to hydrolysis and polymerization of the studied metal ions in their aqueous solutions.