Abstract
As high permittivity dielectrics approach use in metal-oxide-semiconductor field effect transistor (MOSFET) production, an atomic level understanding of their electronic and dielectric properties is being rigorously examined. In our work we illustrate studies leading to such an understanding for the important materials HfO 2 and ZrO 2. Valence and conduction band densities of states for HfO 2/SiO 2/Si and ZrO 2/SiO xN y/n-Si structures were determined by soft X-ray photoemission and inverse photoemission. First principles calculations were used to help in assigning valence band maxima and conduction band minima. The energies of defect states at the band edges were determined by comparing the theoretical and experimental results. From this information, we are able to show that both of these dielectric materials have high enough barriers for both electron and hole transfer. We show that the crystal structure in ultrathin ZrO 2 films has considerable effects on permittivity as well as bandgap. The films reported here are predominantly amorphous below a critical thickness (∼5.4 nm) and transform to the tetragonal phase upon annealing, while thicker films appear tetragonal as grown. Finally, bandgaps obtained from combined PES and IPES studies were compared with the optical bandgap derived from ellipsometry measurements. The difference in the bandgap values found in this comparison can be attributed to the final state effects in the excitation processes of the spectroscopies involved. We discuss the interplay of the dielectric's crystal phase, defects and electronic properties, as well as the impact of this understanding on possible tailoring of the film phase for improving band-gap, band-offset and leakage. Finally, we note that lack of sufficient understanding of the dielectric's phase and electronic properties can have negative impact on the ability to correctly determine a film's EOT.
| Original language | English |
|---|---|
| Title of host publication | AIP Conference Proceedings |
| Pages | 92-101 |
| Number of pages | 10 |
| Volume | 788 |
| DOIs | |
| Publication status | Published - Sep 9 2005 |
| Event | 2005 International Conference on Characterization and Metrology for ULSI Technology - Richardson, TX, United States Duration: Mar 15 2005 → Mar 18 2005 |
Other
| Other | 2005 International Conference on Characterization and Metrology for ULSI Technology |
|---|---|
| Country | United States |
| City | Richardson, TX |
| Period | 3/15/05 → 3/18/05 |
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Keywords
- Band Offsets
- Dielectric Band-gap
- Hafnium dioxide (HfO )
- High-K dielectrics
- MOS Gate Stack
- Photoemission
- Zirconium Dioxide (ZrO )
ASJC Scopus subject areas
- Physics and Astronomy(all)
Cite this
The relation between crystalline phase, electronic structure, and dielectric properties in high-K gate stacks. / Sayan, S.; Croft, M.; Nguyen, N. V.; Emge, T.; Ehrstein, J.; Levin, I.; Suehle, J.; Bartynski, R. A.; Garfunkel, Eric.
AIP Conference Proceedings. Vol. 788 2005. p. 92-101.Research output: Chapter in Book/Report/Conference proceeding › Conference contribution
}
TY - GEN
T1 - The relation between crystalline phase, electronic structure, and dielectric properties in high-K gate stacks
AU - Sayan, S.
AU - Croft, M.
AU - Nguyen, N. V.
AU - Emge, T.
AU - Ehrstein, J.
AU - Levin, I.
AU - Suehle, J.
AU - Bartynski, R. A.
AU - Garfunkel, Eric
PY - 2005/9/9
Y1 - 2005/9/9
N2 - As high permittivity dielectrics approach use in metal-oxide-semiconductor field effect transistor (MOSFET) production, an atomic level understanding of their electronic and dielectric properties is being rigorously examined. In our work we illustrate studies leading to such an understanding for the important materials HfO 2 and ZrO 2. Valence and conduction band densities of states for HfO 2/SiO 2/Si and ZrO 2/SiO xN y/n-Si structures were determined by soft X-ray photoemission and inverse photoemission. First principles calculations were used to help in assigning valence band maxima and conduction band minima. The energies of defect states at the band edges were determined by comparing the theoretical and experimental results. From this information, we are able to show that both of these dielectric materials have high enough barriers for both electron and hole transfer. We show that the crystal structure in ultrathin ZrO 2 films has considerable effects on permittivity as well as bandgap. The films reported here are predominantly amorphous below a critical thickness (∼5.4 nm) and transform to the tetragonal phase upon annealing, while thicker films appear tetragonal as grown. Finally, bandgaps obtained from combined PES and IPES studies were compared with the optical bandgap derived from ellipsometry measurements. The difference in the bandgap values found in this comparison can be attributed to the final state effects in the excitation processes of the spectroscopies involved. We discuss the interplay of the dielectric's crystal phase, defects and electronic properties, as well as the impact of this understanding on possible tailoring of the film phase for improving band-gap, band-offset and leakage. Finally, we note that lack of sufficient understanding of the dielectric's phase and electronic properties can have negative impact on the ability to correctly determine a film's EOT.
AB - As high permittivity dielectrics approach use in metal-oxide-semiconductor field effect transistor (MOSFET) production, an atomic level understanding of their electronic and dielectric properties is being rigorously examined. In our work we illustrate studies leading to such an understanding for the important materials HfO 2 and ZrO 2. Valence and conduction band densities of states for HfO 2/SiO 2/Si and ZrO 2/SiO xN y/n-Si structures were determined by soft X-ray photoemission and inverse photoemission. First principles calculations were used to help in assigning valence band maxima and conduction band minima. The energies of defect states at the band edges were determined by comparing the theoretical and experimental results. From this information, we are able to show that both of these dielectric materials have high enough barriers for both electron and hole transfer. We show that the crystal structure in ultrathin ZrO 2 films has considerable effects on permittivity as well as bandgap. The films reported here are predominantly amorphous below a critical thickness (∼5.4 nm) and transform to the tetragonal phase upon annealing, while thicker films appear tetragonal as grown. Finally, bandgaps obtained from combined PES and IPES studies were compared with the optical bandgap derived from ellipsometry measurements. The difference in the bandgap values found in this comparison can be attributed to the final state effects in the excitation processes of the spectroscopies involved. We discuss the interplay of the dielectric's crystal phase, defects and electronic properties, as well as the impact of this understanding on possible tailoring of the film phase for improving band-gap, band-offset and leakage. Finally, we note that lack of sufficient understanding of the dielectric's phase and electronic properties can have negative impact on the ability to correctly determine a film's EOT.
KW - Band Offsets
KW - Dielectric Band-gap
KW - Hafnium dioxide (HfO )
KW - High-K dielectrics
KW - MOS Gate Stack
KW - Photoemission
KW - Zirconium Dioxide (ZrO )
UR - http://www.scopus.com/inward/record.url?scp=33749661526&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33749661526&partnerID=8YFLogxK
U2 - 10.1063/1.2062944
DO - 10.1063/1.2062944
M3 - Conference contribution
SN - 0735402779
SN - 9780735402775
VL - 788
SP - 92
EP - 101
BT - AIP Conference Proceedings
ER -