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Physical-Chemical Evolution of Hf-aluminates upon Thermal Treatments

Published online by Cambridge University Press:  01 February 2011

B. Crivelli ,
M. Alessandri ,
S. Alberici ,
D. Brazzelli ,
A. C. Elbaz ,
S. Frabboni ,
G. Ghidini ,
J. W. Maes ,
G. Ottaviani  and
G. Pavia
...Show all authors
B. Crivelli
Affiliation:
STMicroelectronics, Via C.Olivetti 2, 20041 Agrate Brianza (MI), Italy
M. Alessandri
Affiliation:
STMicroelectronics, Via C.Olivetti 2, 20041 Agrate Brianza (MI), Italy
S. Alberici
Affiliation:
STMicroelectronics, Via C.Olivetti 2, 20041 Agrate Brianza (MI), Italy
D. Brazzelli
Affiliation:
STMicroelectronics, Via C.Olivetti 2, 20041 Agrate Brianza (MI), Italy
A. C. Elbaz
Affiliation:
STMicroelectronics, Via C.Olivetti 2, 20041 Agrate Brianza (MI), Italy
S. Frabboni
Affiliation:
Department of Physic and Unita' INFM – University of Modena, 41100 Modena, Italy
G. Ghidini
Affiliation:
STMicroelectronics, Via C.Olivetti 2, 20041 Agrate Brianza (MI), Italy
J. W. Maes
Affiliation:
ASM International, B-3001 Leuven, Belgium
G. Ottaviani
Affiliation:
Department of Physic and Unita' INFM – University of Modena, 41100 Modena, Italy
G. Pavia
Affiliation:
STMicroelectronics, Via C.Olivetti 2, 20041 Agrate Brianza (MI), Italy
C. Wiemer
Affiliation:
Laboratorio MDM-INFM, Via C.Olivetti 2, 20041 Agrate Brianza (MI), Italy
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Abstract

This study presents an investigation on physical-chemical stability of (HfO2)x(Al2O3 )1-x alloys upon prolonged post-deposition annealings. Two different Hf-aluminates were deposited by ALCVDTM, containing 34% and 74% Al2O3 mol% respectively. Post-deposition annealings (PDA) were carried out in O2 or N2 atmosphere, at 850°C and 900°C for 30 minutes. Interfacial layer (IL) increase after PDA was detected on all the samples, but with small differences between N2 and O2 treatments. Stack composition was characterized by means of XRR, XRF, RBS and TOF-SIMS. Growth of interface layer was justified by limited oxygen incorporation from external ambient. Silicon diffusion from the substrate into high-k material and aluminum/hafnium redistribution were observed and associated to annealing temperature. XRD and planar TEM analysis evidenced first grain formation and then, in the case of Hf-rich samples, almost complete crystallization. Overall, Hf-aluminates were found to remain XRD amorphous during high temperature prolonged treatments up to 900°C for 74% and 850°C for 34% alloys respectively. Differently from HfO2, (HfO2)0.66(Al2O3 )0.34 alloy was observed to crystallized in orthorhombic phase. Hf-aluminates were also electrically characterized by means of C(V) and I(V) measurements on basic capacitors. Variations in material electrical properties were found consistent with change in physical-chemical film structure. Increase in k value up to 30 was observed on Hf-rich samples crystallized in orthorhombic phase.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 765: Symposium D – CMOS Front-End Materials and Process Technology , 2003 , D2.10
Copyright
Copyright © Materials Research Society 2003

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References

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