X-ray Photoemission and X-ray Absorption Studies of Hf-silicate Dielectric Layers

Journal Article · Sun Jan 01 00:00:00 EST 2006 · Applied Surface Science

DOI:https://doi.org/10.1016/j.apsusc.2006.05.053· OSTI ID:930188

O'Connor, R; Hughes, G; Glans, P; Learmonth, T; Smith, K

Photoelectron spectroscopy and X-ray absorption spectroscopy (XAS) measurements have been performed on HfSi{sub x}O{sub y} and HfSi{sub x}O{sub y}N{sub z} dielectric layers, which are potential candidates as high-k transistor gate dielectrics. The hafnium silicate layers, 3-4 nm thick, were formed by codepositing HfO{sub 2} and SiO{sub 2} (50%:50%) by MOCVD at 485 {sup o}C on a silicon substrate following an IMEC clean. Annealing the HfSi{sub x}O{sub y} layer in a nitrogen atmosphere at 1000 {sup o}C resulted in an increase in the Si{sup 4+} chemical shift from 3.5 to 3.9 eV with respect to the Si{sup 0} peak. Annealing the hafnium silicate layer in a NH3 atmosphere at 800 {sup o}C resulted in the incorporation of 10% nitrogen and the decrease in the chemical shift between the Si{sup 4+} and the Si{sup 0} to 3.3 eV. The results suggest that the inclusion of nitrogen in the silicate layer restricts the tendency of the HfO{sub 2} and the SiO{sub 2} to segregate into separate phases during the annealing step. Synchrotron radiation valence band photoemission studies determined that the valence band offsets were of the order of 3 eV. X-ray absorption measurements show that the band gap of these layers is 4.6 eV and that the magnitude of the conduction band offset is as little as 0.5 eV.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: DE-AC02-98CH10886
• OSTI ID: 930188
• Report Number(s): BNL-80851-2008-JA; ASUSEE; TRN: US0806715
• Journal Information: Applied Surface Science, Vol. 253, Issue 5; ISSN 0169-4332
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
43 PARTICLE ACCELERATORS
ABSORPTION
ABSORPTION SPECTROSCOPY
ANNEALING
CHEMICAL SHIFT
DIELECTRIC MATERIALS
HAFNIUM SILICATES
INCLUSIONS
LAYERS
NITROGEN
PHOTOELECTRON SPECTROSCOPY
PHOTOEMISSION
SILICATES
SILICON
SUBSTRATES
SYNCHROTRON RADIATION
TRANSISTORS
VALENCE
national synchrotron light source