Operando study of HfO2 atomic layer deposition on partially hydroxylated Si(111)
Jones, Rosemary LU ; D’Acunto, Giulio LU ; Shayesteh, Payam LU ; Pinsard, Indiana ; Rochet, François ; Bournel, Fabrice ; Gallet, Jean Jacques ; Head, Ashley and Schnadt, Joachim LU
(2024)
In Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
42(2).
- Abstract
The introduction of atomic layer deposition (ALD), to the microelectronics industry has introduced a large number of new possible materials able to be deposited in layers with atomic thickness control. One such material is the high-κ oxide HfO2; thermally stable and ultrathin HfO2 films deposited by ALD are a significant contender to replace SiO2 as the gate oxide in capacitor applications. We present a mechanistic study of the first deposition cycle of HfO2 on the Si(111) surface using tetrakis(dimethylamido) hafnium (TDMAHf) and water as precursors using operando ambient pressure x-ray photoelectron spectroscopy. Here, we show that the hydroxylation of the clean Si(111) surface by residual... (More)
The introduction of atomic layer deposition (ALD), to the microelectronics industry has introduced a large number of new possible materials able to be deposited in layers with atomic thickness control. One such material is the high-κ oxide HfO2; thermally stable and ultrathin HfO2 films deposited by ALD are a significant contender to replace SiO2 as the gate oxide in capacitor applications. We present a mechanistic study of the first deposition cycle of HfO2 on the Si(111) surface using tetrakis(dimethylamido) hafnium (TDMAHf) and water as precursors using operando ambient pressure x-ray photoelectron spectroscopy. Here, we show that the hydroxylation of the clean Si(111) surface by residual water vapor, resulting in a 0.3 monolayer coverage of hydroxyls, leads to instantaneous full surface coverage of TDMAHf. The change in the atomic ratio of Hf to C/N found during the first deposition half-cycle, however, does not match the assumed immediate ligand loss through reaction with surface hydroxyls. One would expect an immediate loss of ligands, indicated by a Hf:N ratio of approximately 1:3 as TDMAHf deposits onto the surface; however, a Hf:N ratio of 1:3.6 is observed. The partial hydroxylation on the Si(111) surface leads to binding through the TDMAHf ligand N atoms resulting in both N and CH3 being found remaining on the surface post water half-cycle. Although there is evidence of ligand exchange reactions occurring at Si-OH sites, it also seems that N binding can occur on bare Si, highlighting the complexity of the substrate/precursor reaction even when hydroxyls are present. Moreover, the initial low coverage of Si-OH/Si-H appears to severely limit the amount of Hf deposited, which we hypothesize is due to the specific geometry of the initial arrangement of Si-OH/Si-H on the rest- and adatoms.
(Less)
- author
- Jones, Rosemary
LU
; D’Acunto, Giulio
LU
; Shayesteh, Payam
LU
; Pinsard, Indiana
; Rochet, François
; Bournel, Fabrice
; Gallet, Jean Jacques
; Head, Ashley
and Schnadt, Joachim
LU
- organization
- publishing date
- 2024-03-01
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
- volume
- 42
- issue
- 2
- article number
- 022404
- publisher
- American Institute of Physics (AIP)
- external identifiers
-
- scopus:85186355617
- ISSN
- 0734-2101
- DOI
- 10.1116/6.0003349
- language
- English
- LU publication?
- yes
- id
- 370a0ce3-3dfe-4005-bc33-cff7b64e579b
- date added to LUP
- 2024-03-21 16:07:54
- date last changed
- 2024-03-22 09:00:12
@article{370a0ce3-3dfe-4005-bc33-cff7b64e579b,
abstract = {{<p>The introduction of atomic layer deposition (ALD), to the microelectronics industry has introduced a large number of new possible materials able to be deposited in layers with atomic thickness control. One such material is the high-κ oxide HfO<sub>2</sub>; thermally stable and ultrathin HfO<sub>2</sub> films deposited by ALD are a significant contender to replace SiO<sub>2</sub> as the gate oxide in capacitor applications. We present a mechanistic study of the first deposition cycle of HfO<sub>2</sub> on the Si(111) surface using tetrakis(dimethylamido) hafnium (TDMAHf) and water as precursors using operando ambient pressure x-ray photoelectron spectroscopy. Here, we show that the hydroxylation of the clean Si(111) surface by residual water vapor, resulting in a 0.3 monolayer coverage of hydroxyls, leads to instantaneous full surface coverage of TDMAHf. The change in the atomic ratio of Hf to C/N found during the first deposition half-cycle, however, does not match the assumed immediate ligand loss through reaction with surface hydroxyls. One would expect an immediate loss of ligands, indicated by a Hf:N ratio of approximately 1:3 as TDMAHf deposits onto the surface; however, a Hf:N ratio of 1:3.6 is observed. The partial hydroxylation on the Si(111) surface leads to binding through the TDMAHf ligand N atoms resulting in both N and CH<sub>3</sub> being found remaining on the surface post water half-cycle. Although there is evidence of ligand exchange reactions occurring at Si-OH sites, it also seems that N binding can occur on bare Si, highlighting the complexity of the substrate/precursor reaction even when hydroxyls are present. Moreover, the initial low coverage of Si-OH/Si-H appears to severely limit the amount of Hf deposited, which we hypothesize is due to the specific geometry of the initial arrangement of Si-OH/Si-H on the rest- and adatoms.</p>}},
author = {{Jones, Rosemary and D’Acunto, Giulio and Shayesteh, Payam and Pinsard, Indiana and Rochet, François and Bournel, Fabrice and Gallet, Jean Jacques and Head, Ashley and Schnadt, Joachim}},
issn = {{0734-2101}},
language = {{eng}},
month = {{03}},
number = {{2}},
publisher = {{American Institute of Physics (AIP)}},
series = {{Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films}},
title = {{Operando study of HfO<sub>2</sub> atomic layer deposition on partially hydroxylated Si(111)}},
url = {{http://dx.doi.org/10.1116/6.0003349}},
doi = {{10.1116/6.0003349}},
volume = {{42}},
year = {{2024}},
}