TITLE

Atomic layer chemical vapor deposition of ZrO[sub 2]-based dielectric films: Nanostructure and nanochemistry

AUTHOR(S)
Dey, S. K.; Wang, C.-G.; Tang, D.; Kim, M. J.; Carpenter, R. W.; Werkhoven, C.; Shero, E.
PUB. DATE
April 2003
SOURCE
Journal of Applied Physics;4/1/2003, Vol. 93 Issue 7, p4144
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
A 4 nm layer of ZrO[sub x] (targeted x∼2) was deposited on an interracial layer (IL) of native oxide (SiO, t∼1.2 nm) surface on 200 mm Si wafers by a manufacturable atomic layer chemical vapor deposition technique at 300°C. Some as-deposited layers were subjected to a postdeposition, rapid thermal annealing at 700°C for 5 min in flowing oxygen at atmospheric pressure. The experimental x-ray diffraction, x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and high-resolution parallel electron energy loss spectroscopy results showed that a multiphase and heterogeneous structure evolved, which we call the Zr-O/IL/Si stack. The as-deposited Zr-O layer was amorphous ZrO[sub 2]-rich Zr silicate containing about 15% by volume of embedded ZrO[sub 2] nanocrystals, which transformed to a glass nanoceramic (with over 90% by volume of predominantly tetragonal-ZrO[sub 2] (t-ZrO[sub 2]) and monoclinic-ZrO[sub 2] (m-ZrO[sub 2]) nanocrystals) upon annealing. The formation of disordered amorphous regions within some of the nanocrystals, as well as crystalline regions with defects, probably gave rise to lattice strains and deformations. The interracial layer (IL) was partitioned into an upper SiO[sub 2]-rich Zr silicate and the lower SiO[sub x]. The latter was substoichiometric and the average oxidation state increased from Si[sup 0.86+] in SiO[sub 0.43] (as-deposited) to Si[sup 1.32+] in SiO[sub 0.66] (annealed). This high oxygen deficiency in SiO[sub x] was indicative of the low mobility of oxidizing specie in the Zr-O layer. The stacks were characterized for their dielectric properties in the Pt/{Zr-O/IL}/Si metal oxide-semiconductor capacitor (MOSCAP) configuration. The measured equivalent oxide thickness (EOT) was not consistent with the calculated EOT using a bilayer model of ZrO[sub 2] and SiO[sub 2], and the capacitance in accumulation (and therefore, EOT and k[sub Zr-O]) was frequency dispersive, trends well documented in...
ACCESSION #
9353050

 

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