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Alternating Layer Chemical Vapor Deposition (ALD) of Metal Silicates and Oxides for Gate Insulators

Published online by Cambridge University Press:  21 March 2011

Roy G. Gordon
Affiliation:
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
Jill Becker
Affiliation:
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
Dennis Hausmann
Affiliation:
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
Seigi Suh
Affiliation:
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
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Abstract

A new process was developed for deposition of the silicates and oxides of metals such as zirconium and hafnium at low substrate temperatures (100–300°C). The silicon and oxygen source is tris(tert-butoxy)silanol, (tBuO)3SiOH, and the metal precursors are metal amides. A typical reaction is

ZrL4 + 2 (tBuO)3SiOH → ZrSi2O6 + 4HL + 6H2C=C(CH3)2 + 2 H2O

in which the ligand L is ethylmethylamide, -NEtMe. The precursor vapors were alternately pulsed into a heated reactor, yielding about 0.3 to 0.7 nm of metal silicate film for each cycle. Replacing the silanol pulses with water pulses yields pure metal oxides with a thickness of about 0.1 to 0.15 nm per cycle. The silicon content of the films can be adjusted to any desired value by replacing some of the silanol pulses by water pulses. This new process has a number of advantages over previous methods for depositing metal silicates. Uniformity of thickness and stoichiometry are readily achieved. The deposition atmosphere is non-oxidizing, so that formation of low-k interfacial oxides between the deposited layer and a silicon substrate is minimized. The new halogen-free precursors avoid halogen contamination of films and corrosion of deposition systems. This process is a promising method for forming the next generation of ultra-thin high-k gate dielectrics in silicon-based microelectronics.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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References

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