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A Comparison of Electrical and Physical Properties of MOCVD Hafnium Silicate Thin Films Deposited using Various Silicon Precursors

Published online by Cambridge University Press:  01 February 2011

Paul Jamison
Affiliation:
pjamison@us.ibm.com, IBM, Microelectronics Division, Thomas J. Watson Research Center, 8-140, Yorktown Heights, NY, 10598, United States, 914-945-2209
M Copel
Affiliation:
mcopel@us.ibm.com, IBM, Research Division, TJ Watson Research Center, 1101 Kitchawan Rd, Yorktown Heights, NY, 10598, United States
M Chudzik
Affiliation:
chudzik@us.ibm.com, IBM, Systems & Technology Group, 2070 Route 52, Hopewell Junction, NY, 12533, United States
M M Frank
Affiliation:
mmfrank@us.ibm.com, IBM, Research Division, TJ Watson Research Center, 1101 Kitchawan Rd, Yorktown Heights, NY, 10598, United States
B P Linder
Affiliation:
bplinder@us.ibm.com, IBM, Research Division, TJ Watson Research Center, 1101 Kitchawan Rd, Yorktown Heights, NY, 10598, United States
R Jammy
Affiliation:
jammyr@us.ibm.com, IBM, Research Division, TJ Watson Research Center, 1101 Kitchawan Rd, Yorktown Heights, NY, 10598, United States
W Zhu
Affiliation:
wenjuan@us.ibm.com, IBM, Systems & Technology Group, 2070 Route 52, Hopewell Junction, NY, 12533, United States
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Abstract

We report on the impact of silicon precursor choice on the electrical and physical properties of hafnium silicate (HfSiO) gate dielectrics deposited by metalorganic chemical vapor deposition (MOCVD). Hafnium tert-butoxide (HTB) was used as the hafnium source and silane and tetraethylorthosilicate (TEOS) were used as silicon sources. Elemental depth profiles were measured with sub-nm resolution using medium energy ion scattering (MEIS). For Hf-rich films employing TEOS as the silicon precursor, relatively little Si is incorporated at the bottom interface compared with the top; while using SiH4, a more uniform Si distribution is achieved. These physical differences are then correlated with the electrical performance of transistors employing polysilicon gate electrodes. Transistors incorporating SiH4 based HfSiOx gate dielectrics with low silicon concentrations have lower C-V hysteresis and higher high field mobility than those using TEOS based dielectrics. We demonstrate polysilicon gated transistors which have an electrical thickness in inversion (Tinv) that can be scaled to ~21 A with good leakage reduction when employing nitrided bottom interface layers in combination with optimized HfSiOx dielectrics. Reduced silicon concentration resulted in a lower inversion thickness for a fixed physical thickness contributing to the higher drive currents in transistors.

Type
Research Article
Copyright
Copyright © Materials Research Society 2006

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References

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