Plasma-assisted atomic layer deposition of HfNx: tailoring the film properties by the plasma gas composition

S. Karwal, B.L. Williams, J. Niemelä, M.A. Verheijen, W.M.M. Kessels, M. Creatore

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The authors synthesized HfNx (x ≥ 1) thin films by plasma-assisted atomic layer deposition at stage temperatures of 350–450 °C by using the high-thermal-stability CpHf(NMe2)3 monomer as Hf precursor and either H2 plasma or N2 plasma as coreactant. Most notably, the selection of the plasma gas composition enabled us to tune the film properties: films fabricated using N2 plasma led to the formation of highly resistive and amorphous Hf3N4 films (6 × 102 Ω cm), while the use of the strongly reducing H2 plasma generated conductive (resistivity of 6 × 10−1 Ω cm) films with the signature of the δ-HfN fcc crystal structure. Via x-ray photoelectron spectroscopy, the authors observed that the use of the H2 plasma facilitates the reduction of the oxidation state of Hf from Hf4+ to Hf3+. This result was corroborated by the simultaneous increase in the free carrier absorption observed in the infrared range via spectroscopic ellipsometry. The δ-HfNx films fabricated via the present route are promising as highly reflective back contacts for thin films solar cells, Cu diffusion barriers, and as a gate metal for metal–oxide–semiconductor capacitors, provided that the resistivity values can be further decreased by suppressing the formation of the resistive Hf2ON2 impurity phase and grain-boundary scattering of the charge carriers.
Originele taal-2Engels
Artikelnummer01B129
Pagina's (van-tot)1-8
Aantal pagina's8
TijdschriftJournal of Vacuum Science and Technology A: Vacuum, Surfaces, and Films
Volume35
Nummer van het tijdschrift1
DOI's
StatusGepubliceerd - jan 2017

Citeer dit

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title = "Plasma-assisted atomic layer deposition of HfNx: tailoring the film properties by the plasma gas composition",
abstract = "The authors synthesized HfNx (x ≥ 1) thin films by plasma-assisted atomic layer deposition at stage temperatures of 350–450 °C by using the high-thermal-stability CpHf(NMe2)3 monomer as Hf precursor and either H2 plasma or N2 plasma as coreactant. Most notably, the selection of the plasma gas composition enabled us to tune the film properties: films fabricated using N2 plasma led to the formation of highly resistive and amorphous Hf3N4 films (6 × 102 Ω cm), while the use of the strongly reducing H2 plasma generated conductive (resistivity of 6 × 10−1 Ω cm) films with the signature of the δ-HfN fcc crystal structure. Via x-ray photoelectron spectroscopy, the authors observed that the use of the H2 plasma facilitates the reduction of the oxidation state of Hf from Hf4+ to Hf3+. This result was corroborated by the simultaneous increase in the free carrier absorption observed in the infrared range via spectroscopic ellipsometry. The δ-HfNx films fabricated via the present route are promising as highly reflective back contacts for thin films solar cells, Cu diffusion barriers, and as a gate metal for metal–oxide–semiconductor capacitors, provided that the resistivity values can be further decreased by suppressing the formation of the resistive Hf2ON2 impurity phase and grain-boundary scattering of the charge carriers.",
author = "S. Karwal and B.L. Williams and J. Niemel{\"a} and M.A. Verheijen and W.M.M. Kessels and M. Creatore",
year = "2017",
month = "1",
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journal = "Journal of Vacuum Science and Technology A: Vacuum, Surfaces, and Films",
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Plasma-assisted atomic layer deposition of HfNx: tailoring the film properties by the plasma gas composition. / Karwal, S.; Williams, B.L.; Niemelä, J.; Verheijen, M.A.; Kessels, W.M.M.; Creatore, M.

In: Journal of Vacuum Science and Technology A: Vacuum, Surfaces, and Films, Vol. 35, Nr. 1, 01B129, 01.2017, blz. 1-8.

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

TY - JOUR

T1 - Plasma-assisted atomic layer deposition of HfNx: tailoring the film properties by the plasma gas composition

AU - Karwal, S.

AU - Williams, B.L.

AU - Niemelä, J.

AU - Verheijen, M.A.

AU - Kessels, W.M.M.

AU - Creatore, M.

PY - 2017/1

Y1 - 2017/1

N2 - The authors synthesized HfNx (x ≥ 1) thin films by plasma-assisted atomic layer deposition at stage temperatures of 350–450 °C by using the high-thermal-stability CpHf(NMe2)3 monomer as Hf precursor and either H2 plasma or N2 plasma as coreactant. Most notably, the selection of the plasma gas composition enabled us to tune the film properties: films fabricated using N2 plasma led to the formation of highly resistive and amorphous Hf3N4 films (6 × 102 Ω cm), while the use of the strongly reducing H2 plasma generated conductive (resistivity of 6 × 10−1 Ω cm) films with the signature of the δ-HfN fcc crystal structure. Via x-ray photoelectron spectroscopy, the authors observed that the use of the H2 plasma facilitates the reduction of the oxidation state of Hf from Hf4+ to Hf3+. This result was corroborated by the simultaneous increase in the free carrier absorption observed in the infrared range via spectroscopic ellipsometry. The δ-HfNx films fabricated via the present route are promising as highly reflective back contacts for thin films solar cells, Cu diffusion barriers, and as a gate metal for metal–oxide–semiconductor capacitors, provided that the resistivity values can be further decreased by suppressing the formation of the resistive Hf2ON2 impurity phase and grain-boundary scattering of the charge carriers.

AB - The authors synthesized HfNx (x ≥ 1) thin films by plasma-assisted atomic layer deposition at stage temperatures of 350–450 °C by using the high-thermal-stability CpHf(NMe2)3 monomer as Hf precursor and either H2 plasma or N2 plasma as coreactant. Most notably, the selection of the plasma gas composition enabled us to tune the film properties: films fabricated using N2 plasma led to the formation of highly resistive and amorphous Hf3N4 films (6 × 102 Ω cm), while the use of the strongly reducing H2 plasma generated conductive (resistivity of 6 × 10−1 Ω cm) films with the signature of the δ-HfN fcc crystal structure. Via x-ray photoelectron spectroscopy, the authors observed that the use of the H2 plasma facilitates the reduction of the oxidation state of Hf from Hf4+ to Hf3+. This result was corroborated by the simultaneous increase in the free carrier absorption observed in the infrared range via spectroscopic ellipsometry. The δ-HfNx films fabricated via the present route are promising as highly reflective back contacts for thin films solar cells, Cu diffusion barriers, and as a gate metal for metal–oxide–semiconductor capacitors, provided that the resistivity values can be further decreased by suppressing the formation of the resistive Hf2ON2 impurity phase and grain-boundary scattering of the charge carriers.

U2 - 10.1116/1.4972208

DO - 10.1116/1.4972208

M3 - Article

VL - 35

SP - 1

EP - 8

JO - Journal of Vacuum Science and Technology A: Vacuum, Surfaces, and Films

JF - Journal of Vacuum Science and Technology A: Vacuum, Surfaces, and Films

SN - 0734-2101

IS - 1

M1 - 01B129

ER -