Atmospheric-pressure spatial atomic layer deposition (s-ALD) has emerged as a scalable deposition technique combining the advantages of ALD with high deposition rates, suitable for low-cost and high-volume applications. There is a growing interest in atmospheric-pressure plasma-enhanced spatial ALD (PE-s-ALD), e.g., to allow for deposition at reduced temperatures or for materials that are otherwise difficult to prepare by thermal ALD. For low-pressure PE-ALD, conformal films on high aspect ratio features have been achieved despite plasma radical recombination, and the aspects influencing conformality are fairly well understood. This work addresses surface recombination and conformality for atmospheric-pressure PE-s-ALD films. We demonstrate that conformality can be achieved for SiO2 and TiO2 films deposited by atmospheric-pressure PE-s-ALD inside high-aspect-ratio trenches with short plasma exposure times. Using plasma exposure of 0.73 s results in conformal SiO2 and TiO2 films in structures with aspect ratios of 74 and 219, respectively. Additionally, the recombination probabilities of oxygen radicals at atmospheric pressure are extracted to be 4 × 10 4 for SiO2 and 6 × 10 5 for TiO2. These results demonstrate that atmospheric-pressure PE-s-ALD can be used for conformal and high-speed depositions on 3D substrates.

Atmospheric-pressure spatial atomic layer deposition (s-ALD) is an emerging technology for depositing high-quality thin films for low-cost high-volume applications.1 Using a plasma as co-reactant has the additional benefit of a more comprehensive materials selection and enlarged set of compatible precursors,2,3 as well as lower deposition temperatures,4 and in some cases improved film properties.4,5 Although low-pressure temporal ALD is known to be able to deposit highly conformal films, potential challenges arise when using atmospheric-pressure plasma-enhanced s-ALD (PE-s-ALD). First, the partial pressure of reactive plasma species can quickly drop inside high-aspect-ratio structures due to surface recombination while the effect of using high reactor pressures on recombination probabilities is unknown. Second, high pressures can lead to gas-phase collisions and low diffusion coefficients causing reactive species to diffuse less deep than for low-pressure ALD.6 

Continuum models, based on pioneering work by Gordon et al.,7 have been used to gain a theoretical understanding of the conformality of thermal ALD.8–14 By adding a non-saturating reactant loss mechanism to describe recombination of plasma radicals, such models can be applied to PE-ALD,9 and can even be used to directly determine the recombination probability r.15 The recombination probability is highly dependent on the surface material. Arts et al. found r-values of oxygen radicals during the deposition of oxides to vary from 10 5 for SiO2 and TiO2 to 10 3 10 2 for Al2O3 and HfO2.15,16 So far, only the conformality of low-pressure PE-ALD processes has been studied.17,18 The step coverage of atmospheric-pressure s-ALD has only been studied for thermal processes.6,19 At high reactor pressure, the mean free path of oxygen radicals is shorter than at low pressure, so more gas-phase and wall collisions can be expected for atmospheric-pressure PE-s-ALD as compared to low-pressure ALD, potentially leading to lower penetration depths. Additionally, r has been found to be pressure dependent, typically increasing with pressure.20,21 Yet, Arts et al. have shown reduced r with increasing pressure in the 12–130 mTorr range.16 Clearly, several questions remain concerning the conformality of PE-ALD.

In this Letter, the conformality of PE-s-ALD deposited SiO2 and TiO2 is systematically studied in 3D structures. We demonstrate large penetration depths for subsecond plasma exposure times and we extract r of oxygen radicals during these processes at atmospheric pressure. Moreover, we demonstrate that the plasma exposure times required for achieving saturation in structures with a wide range of aspect ratios are lower than for low-pressure PE-ALD.

The penetration depths of the deposited films in high-aspect-ratio structures were studied by employing the lateral-high-aspect-ratio (LHAR) method enabled by PillarHall LHAR test chips (Chipmetrics Ltd).22 These Si chips of 15 × 15 mm2 contain LHAR trenches of various lengths. The type of PillarHall substrate used in this work is the LHAR4 chip, with 500 nm high trenches varying in length from 1 up to 5024 μm, resulting in aspect ratios up to 10 000. These high aspect ratios ensure that the depositions are in the recombination-limited regime. One sidewall of the horizontal trenches consists of Si membranes that can be removed with adhesive tape after depositions to expose the other sidewall of the trenches and allow for thickness and material analysis. The penetration depths of SiO2 and TiO2 films were determined for various plasma exposure times and used to determine r of oxygen radicals using the method developed by Arts et al.15 To use this method at atmospheric pressure, some alterations to the model—related to the diffusion of the oxygen radicals—were required. The diffusion is influenced by the geometry of the structures (Fig. S1 in the supplementary material shows the influence of trench height on the diffusion coefficient at these deposition conditions) and the deposition conditions. In this work, the depositions were performed at 100 °C and atmospheric pressure ( 10 5 Pa), using a 2% O2 in N2 plasma as a co-reactant.

There are two distinct regimes for particles diffusing inside a 3D structure. In the Knudsen diffusion regime, the mean free path of the particles is larger than the limiting dimensions of the structure. Therefore, the particles primarily collide with the structure walls, and particle–particle interactions are negligible. In the molecular diffusion regime, the mean free path is shorter than the structure dimensions. Therefore, most particle collisions are with other particles. To adapt the model used by Arts et al. (see the supplementary material) to atmospheric pressure, the diffusion regime needs to be determined. This is done by evaluating the Knudsen number K n = λ 0 , A / d, which depends on the limiting structure dimension d (m) and the specific scattering length λ 0 , A (m) of species A in a carrier gas B,
λ 0 , A = k B T 2 P A σ A , A + 1 + m A m B P B σ A , B ,
(1)
with Boltzmann constant k B (m2 kg s−2 K−1), temperature T (K), partial pressure P i (Pa), and mass m i (kg) of particle i.23 The collisional cross section σ i , j (m2) between particles i and j with radii r i (m) and r j (m) is
σ i , j = π r i 2 + r j 2 .
(2)
Depositions happen in the Knudsen diffusion regime if K n 1, the molecular diffusion regime if K n 1, and a transitional regime if K n 1. Each of these regimes has a different diffusion coefficient: the Knudsen diffusion coefficient D Kn (m2 s−1) in the Knudsen regime, the binary diffusion coefficient D i j (m2 s−1) for particles i in carrier gas j in the molecular diffusion regime, and the effective diffusion coefficient D eff (m2 s−1) in the transitional diffusion regime given by
D eff = 1 D kn + 1 D i j 1 .
(3)

The deposition conditions and trench structures used in this work give a specific scattering length of oxygen λ 0 , O = 2 × 10 7 m [Eq. (1)] and result in K n = 0.4, corresponding to the transitional diffusion regime.

Standard metrics when analyzing conformality using high-aspect-ratio structures are the 50% thickness penetration depth (PD50%) and the scaled 50% thickness penetration depth PD 50 % / h, which is a measure for the obtained aspect ratio. Additionally, the 50% saturation time t 50 % is used to describe the required dosing time for 50% saturation on a planar surface. The relation for the logarithmic scaling of PD 50 % / h with t is
PD 50 % h t = 1 a r ln t t 50 % .
(4)

Here, a denotes a term dependent on the diffusion regime of the system. For Knudsen diffusion, a equals ¾.15 In the case of molecular diffusion, a equals v th h 2 D i j, where the thermal velocity v th is calculated using v th = 8 k B T m π. In the intermediate case, such as in this work, the use of D eff is required, resulting in the substitution of a with 3 D i j + 2 v th h 4 D i j.

The value for D O N 2 was determined to be 5 × 10–5 m2 s−1 under the deposition conditions, based on the empirical methods by Fuller et al. and by Marrero and Mason, which both yielded similar results.24,25 Therefore, the deposition conditions of this work result in
PD 50 % h t = 1 4.26 r ln t t 50 % ,
(5)
which is used to determine r from the experimental data. This is accomplished by plotting the experimental data as PD 50 % / h vs ln ( t ) and fitting with a linear function. The slope, then, equals 1 / 4.26 r.

Thin films were deposited using an atmospheric-pressure s-ALD tool with a rotating substrate table (Fig. 1) described in detail by Poodt et al.26 The deposition head was equipped with a precursor inlet and a dielectric-barrier discharge (DBD) plasma source (SparkNano B.V.) positioned opposite of each other.27 Data will be presented for LHAR trench openings that were oriented perpendicular to the precursor and plasma inlets, although it was observed that the trench orientation does not affect the deposition (see Fig. S4 in the supplementary material). SiO2 and TiO2 were deposited using precursors bis(diethylamino)silane (BDEAS, SiH2(NEt2)2, bubbler temperature = 50 °C), and tetrakis(dimethylamido)titanium (TDMAT, Ti(NMe2)4 bubbler temperature = 40 °C), respectively. A plasma was used with a 10 slm flow of N2 with 2% O2 by applying 50 V. For SiO2 and TiO2, 200 and 420 cycles were deposited, respectively. Depositions took place at 100 °C and 1 × 10 5 Pa while varying the rotation frequency of the substrate table: 1, 2, and 3 rpm, corresponding to plasma exposure times of 0.73, 0.37, and 0.24 s, respectively. The plasma-source-to-substrate distance was 200 μm. See Fig. S5 in the supplementary material for the influence of the plasma height on the thickness profile of SiO2.

FIG. 1.

(a) Schematic of the rotary spatial ALD tool used to deposit films in LHAR structures schematically shown in (b), which were analyzed after removing the membrane. (c) Optical microscopy image showing the deposited film on the exposed sidewall of the structure.

FIG. 1.

(a) Schematic of the rotary spatial ALD tool used to deposit films in LHAR structures schematically shown in (b), which were analyzed after removing the membrane. (c) Optical microscopy image showing the deposited film on the exposed sidewall of the structure.

Close modal

In addition to the PillarHall test chips, a planar reference wafer was used during each deposition to determine the film composition using x-ray photoelectron spectroscopy (XPS) with a Thermo Fischer Scientific K-alpha x-ray photoelectron spectrometer. The deposited films were nearly stoichiometric, with Si:O ratios of 0.47  ± 0.01 for the SiO2 films and Ti:O ratios of 0.50  ± 0.02 for the TiO2 films. The SiO2 films were free of carbon, while the TiO2 films contained trace amounts (<1 at. %). Thickness profiles were measured inside the trenches using a J.A. Woollam Small-Spot size (25 × 40 μm2) RC2 spectroscopic ellipsometer (SE). Measurements were performed over a spectral range of 0.8–5.9 eV. The SiO2 refractive index was modeled using a Sellmeier-type dispersion, which matched the experimental data from multiple locations (with varying thicknesses). These pre-determined optical constants were fixed to determine the thickness variation of the SiO2 films. The refractive indices of the SiO2 films ranged from 1.46 to 1.48 at 633 nm, and the growth per cycle (GPC) was 1.4–1.5 Å/cycle. These values are in line with the earlier work on a similar rotary PE-s-ALD setup using the same precursor and temperature.28 Furthermore, the refractive indices were constant throughout the LHAR structures. For the TiO2, however, this was not the case, as a lower refractive index was observed inside the trench. Several regions inside the trench were fitted with Kramers–Kronig consistent b-spline functions to create a composition-shifting material file.29 This file was used to determine the thicknesses while accounting for variations in the optical constants throughout the film, within set boundaries (see the supplementary material for more detail). Outside the structures, the refractive indices were 2.35–2.43 at 633 nm and the GPC was 0.60–0.64 Å/cycle. The drop in refractive index has not been reported in the previous work at low pressure, because reflectometry was used to measure the thickness instead of SE, while assuming a constant refractive index.5,15

Thickness profiles of the films deposited inside LHAR structures are shown in Fig. 2. The thickness of the SiO2 films remains constant upon entering the trench, up until the so-called deposition fronts, where the thickness quickly decreases to zero. The radical density decreases throughout the trench and at the deposition front the radical density becomes limiting for film growth, before the radicals become depleted. The shape of the SiO2 thickness curves is similar to what was observed in the earlier work.15,16 Although the thickness profiles of TiO2 look mostly similar, they exhibit an increased thickness at the trench entrance. This profile and the changing refractive index throughout the trench will be investigated in more detail in future work. As expected, the penetration depth increases with plasma exposure time for both materials. Even with plasma exposure times as short as 0.73 s, aspect ratios of 73.5 and 218.5 were achieved for SiO2 and TiO2, respectively. These aspect ratios are sufficient for most ALD applications. Although depositions with aspect ratios larger than 800 were previously obtained for low-pressure PE-ALD, long plasma exposure times of 120 s were used during those depositions.15 In contrast, these atmospheric-pressure PE-s-ALD results show remarkably good conformality for subsecond plasma exposure times. For comparison with other research, the aspect ratios obtained for these trenches can be converted to equivalent aspect ratio (EAR), corresponding to cylindrical pores as a reference structure, using EAR = A R trench / 2.23 

FIG. 2.

Thickness profiles of (a) SiO2 and (b) TiO2 films deposited at 100 °C inside lateral high-aspect-ratio structures by PE-s-ALD with varying plasma exposure times per cycle. The dashed line indicates the position of the trench opening. The systematic error for each data point is estimated to be  1 nm.

FIG. 2.

Thickness profiles of (a) SiO2 and (b) TiO2 films deposited at 100 °C inside lateral high-aspect-ratio structures by PE-s-ALD with varying plasma exposure times per cycle. The dashed line indicates the position of the trench opening. The systematic error for each data point is estimated to be  1 nm.

Close modal

In order to further analyze these depositions and to extract the recombination probabilities, r, of oxygen radicals during processing, PD 50 % / h was plotted as a function of the logarithm of the plasma exposure time and a linear fit was applied. These results (Fig. 3) show the logarithmic scaling of plasma exposure time with penetration depth expected for recombination-limited depositions. From Eq. (5), it follows that the slope of the linear fit equals 1 / 4.26 r. The obtained recombination probabilities were 4 × 10 4 for SiO2 and 6 × 10 5 for TiO2. These values are only slightly higher than what was reported by Arts et al. at 50 mTorr (i.e., 9 × 10 5 for SiO2 and 4 × 10 5 for TiO2).16 Remarkably, the influence of a significant pressure difference on r appears limited, and radical recombination on SiO2 and especially on TiO2 is still very small at atmospheric pressure. Note that Arts et al. investigated the pressure dependence over a relatively small pressure range (12–130 mTorr) and found a decreasing trend of r with pressure withing this range.

FIG. 3.

Scaled half-thickness penetration depths of SiO2 and TiO2 films grown at 100 °C with PE-s-ALD inside LHAR structures for various plasma exposure times. The error bar on the first TiO2 data point is extended toward lower values to account for the possibility that this deposition is not fully recombination limited.16 Recombination probabilities r were determined by linear fits to Eq. (5) through the data.

FIG. 3.

Scaled half-thickness penetration depths of SiO2 and TiO2 films grown at 100 °C with PE-s-ALD inside LHAR structures for various plasma exposure times. The error bar on the first TiO2 data point is extended toward lower values to account for the possibility that this deposition is not fully recombination limited.16 Recombination probabilities r were determined by linear fits to Eq. (5) through the data.

Close modal
In addition to extracting r from the scaled penetration depths of the depositions, the model can be used to estimate the plasma exposure time required to reach a specific aspect ratio. To this end, t 50 % was calculated from the linear fits (see the supplementary material). An overview of the extracted r and t 50 % at atmospheric pressure can be seen in Table I along with values at low pressure. From r and t 50 %, the plasma saturation time t sat, defined as the time required to reach 50% saturation at the bottom of a structure, is determined as a function of the aspect ratio (Fig. 4) as
t sat t 50 % exp 4.26 r A R .
(6)
TABLE I.

Summary of r and t50% values determined in this work for SiO2 and TiO2 deposited using PE-s-ALD at 100 °C and atmospheric pressure. Reference values from Arts et al., J. Phys. Chem. C 125, 15 (2021), licensed under a Creative Commons Attribution (CC BY) license, for low-pressure PE-ALD at 100 °C and 50 mTorr are included for comparison.16 

Material Atmospheric-pressure r Atmospheric-pressure t 50 % (s) Low-pressure r Low-pressure t 50 % (s)
SiO2  (4 ± 2) × 10−4  (4 ± 1) × 10−2  (9 ± 4) × 10−5  0.2 ± 0.1 
TiO2  (6 ± 1) × 10−5  (2 ± 1) × 10−2  (4 ± 2) × 10−5  0.8 ± 0.4 
Material Atmospheric-pressure r Atmospheric-pressure t 50 % (s) Low-pressure r Low-pressure t 50 % (s)
SiO2  (4 ± 2) × 10−4  (4 ± 1) × 10−2  (9 ± 4) × 10−5  0.2 ± 0.1 
TiO2  (6 ± 1) × 10−5  (2 ± 1) × 10−2  (4 ± 2) × 10−5  0.8 ± 0.4 
FIG. 4.

Plasma saturation time for conformal coating of trenches with various aspect ratios using SiO2 and TiO2. Datapoints are given for atmospheric-pressure depositions and the trend in the plasma saturation time is calculated using the extracted values of r and t 50 % (see Table I).

FIG. 4.

Plasma saturation time for conformal coating of trenches with various aspect ratios using SiO2 and TiO2. Datapoints are given for atmospheric-pressure depositions and the trend in the plasma saturation time is calculated using the extracted values of r and t 50 % (see Table I).

Close modal

The exact t 50 % and t sat values vary from reactor to reactor as they depend on many factors (e.g., type of plasma source, plasma power, and plasma-to-substrate distance), yet it is clear that t sat increases more with increasing aspect ratios at atmospheric pressure compared to low pressure. The difference is caused by the difference in diffusion (i.e., shorter mean free path of oxygen radicals leads to more wall collisions, and thus more recombination) as well as the slightly higher recombination probability. Despite this difference, t sat is actually lower at atmospheric pressure for a wide range of aspect ratios, i.e., 0–50 for SiO2 and 0–300 for TiO2. This is due to a lower t 50 %. Since the atmospheric-pressure plasma generates a higher radical density than the low-pressure plasma, saturation of the plasma exposure step is faster on planar surfaces. This effect is gradually offset by the shorter mean free path and higher r for surfaces with increasing aspect ratios. The short t sat is a clear benefit of using atmospheric pressure PE-s-ALD on 3D substrates.

In conclusion, we have demonstrated that SiO2 and TiO2 films deposited using atmospheric-pressure PE-s-ALD with short plasma exposure times can have excellent conformality. Aspect ratios of 74 and 219 for SiO2 and TiO2, respectively, were reached using only 0.73 s of plasma exposure, sufficient for coating 3D substrates in many applications. Additionally, we have shown that the established method of determining r of plasma radicals on the deposited material at low pressure can be used at atmospheric pressure by accounting for the difference in the diffusion of the radicals inside the structure. The recombination probability of oxygen radicals was determined to be 4 × 10 4 and 6 × 10 5 on SiO2 and TiO2, respectively. Despite slightly higher r values and lower diffusion coefficients of oxygen radicals compared to low-pressure PE-ALD, atmospheric-pressure PE-s-ALD can yield lower plasma saturation times for aspect ratios up to 50 for SiO2 and 300 for TiO2. These findings demonstrate the compatibility of atmospheric pressure PE-s-ALD as high-throughput thin-film deposition method for demanding applications.

See the supplementary material for a summary of the continuum model for the conformality of low-pressure PE-ALD, the influence of trench height on the diffusion coefficient of O atoms, the modeling of SE data, and thickness profiles of SiO2 deposited using various plasma heights.

This work was supported by the Netherlands Organization for Scientific Research (NWO) through the project titled Spatial Atomic Layer Deposition: More Materials, More Demanding Applications with Project No. 18697.

The authors have no conflicts to disclose.

Mike L. van de poll: Conceptualization (equal); Data curation (equal); Formal analysis (equal); Investigation (equal); Methodology (equal); Visualization (equal); Writing – original draft (equal); Writing – review & editing (equal). Hardik Jain: Data curation (equal); Investigation (equal). James Hilfiker: Data curation (equal); Formal analysis (equal); Writing – review & editing (equal). Mikko Utriainen: Methodology (equal); Resources (equal); Writing – review & editing (equal). Paul Poodt: Conceptualization (equal); Resources (equal); Supervision (equal); Writing – review & editing (equal). W. M. M. Kessels: Conceptualization (equal); Funding acquisition (equal); Project administration (equal); Supervision (equal); Validation (equal); Writing – review & editing (equal). Bart Macco: Conceptualization (equal); Funding acquisition (equal); Project administration (equal); Supervision (equal); Validation (equal); Writing – review & editing (equal).

The data that support the findings of this study are available from the corresponding author upon reasonable request.

1.
P.
Poodt
,
D. C.
Cameron
, and
E.
Dickey
, “
Spatial atomic layer deposition: A route towards further industrialization of atomic layer deposition
,”
J. Vac. Sci. Technol. A
30
,
10802
(
2012
).
2.
S. J.
Won
,
S.
Suh
,
M. S.
Huh
, and
H. J.
Kim
, “
High-quality low-temperature silicon oxide by plasma-enhanced atomic layer deposition using a metalorganic silicon precursor and oxygen radical
,”
IEEE Electron Device Lett.
31
,
857
859
(
2010
).
3.
See https://www.atomiclimits.com/alddatabase/ for Atomic Limits ALD Database. doi:10.6100/alddatabase.
4.
H. B.
Profijt
,
S. E.
Potts
,
M. C. M.
van de Sanden
, and
W. M. M.
Kessels
, “
Plasma-assisted atomic layer deposition: Basics, opportunities, and challenges
,”
J. Vac. Sci. Technol. A
29
,
050801
(
2011
).
5.
K.
Arts
,
H.
Thepass
,
M. A.
Verheijen
et al, “
Impact of ions on film conformality and crystallinity during plasma-assisted atomic layer deposition of TiO2
,”
Chem. Mater.
33
,
5002
5009
(
2021
).
6.
P.
Poodt
,
A.
Mameli
,
J.
Schulpen
,
W. M. M.
(Erwin) Kessels
, and
F.
Roozeboom
, “
Effect of reactor pressure on the conformal coating inside porous substrates by atomic layer deposition
,”
J. Vac. Sci. Technol. A
35
,
021502
(
2016
).
7.
R. G.
Gordon
,
D.
Hausmann
,
E.
Kim
, and
J.
Shepard
, “
A kinetic model for step coverage by atomic layer deposition in narrow holes or trenches
,”
Chem. Vap. Depos.
9
,
73
78
(
2003
).
8.
H. Y.
Lee
,
C. J.
An
,
S. J.
Piao
et al, “
Shrinking core model for Knudsen diffusion-limited atomic layer deposition on a nanoporous monolith with an ultrahigh aspect ratio
,”
J. Phys. Chem. C
114
,
18601
18606
(
2010
).
9.
A.
Yanguas-Gil
and
J. W.
Elam
, “
Self-limited reaction-diffusion in nanostructured substrates: Surface coverage dynamics and analytic approximations to ALD saturation times
,”
Chem. Vap. Depos.
18
,
46
52
(
2012
).
10.
N.
Yazdani
,
V.
CHawla
,
E.
Edwards
et al, “
Modeling and optimization of atomic layer deposition processes on vertically aligned carbon nanotubes
,”
Beilstein J. Nanotechnol.
5
(
5
),
234
244
(
2014
).
11.
T.
Keuter
,
N. H.
Menzler
,
G.
Mauer
et al, “
Modeling precursor diffusion and reaction of atomic layer deposition in porous structures
,”
J. Vac. Sci. Technol. A
33
,
01A104
(
2015
).
12.
M.
Ylilammi
,
O. M. E.
Ylivaara
, and
R. L.
Puurunen
, “
Modeling growth kinetics of thin films made by atomic layer deposition in lateral high-aspect-ratio structures
,”
J. Appl. Phys.
123
,
205301
(
2018
).
13.
A. J.
Gayle
,
Z. J.
Berquist
,
Y.
Chen
et al, “
Tunable atomic layer deposition into ultra-high-aspect-ratio (>60000:1) aerogel monoliths enabled by transport modeling
,”
Chem. Mater.
33
,
5572
5583
(
2021
).
14.
J.
Yim
,
E.
Verkama
,
J. A.
Velasco
,
K.
Arts
, and
R. L.
Puurunen
, “
Conformality of atomic layer deposition in microchannels: Impact of process parameters on the simulated thickness profile
,”
Phys. Chem. Chem. Phys.
24
,
8645
(
2022
).
15.
K.
Arts
,
M.
Utriainen
,
R. L.
Puurunen
,
W. M. M.
Kessels
, and
H. C. M.
Knoops
, “
Film conformality and extracted recombination probabilities of O atoms during plasma-assisted atomic layer deposition of SiO2, TiO2, Al2O3, and HfO2
,”
J. Phys. Chem. C
123
,
27030
27035
(
2019
).
16.
K.
Arts
,
S.
Deijkers
,
R. L.
Puurunen
,
W. M. M.
Kessels
, and
H. C. M.
Knoops
, “
Oxygen recombination probability data for plasma-assisted atomic layer deposition of SiO2 and TiO2
,”
J. Phys. Chem. C
125
,
8244
8252
(
2021
).
17.
B.
Ho Choi
,
Y.
Hwam Lim
,
J.
Ho Lee
et al, “
Preparation of Ru thin film layer on Si and TaN/Si as diffusion barrier by plasma enhanced atomic layer deposition
,”
Microelectron. Eng.
87
,
1391
1395
(
2010
).
18.
J.
Dendooven
,
D.
Deduytsche
,
J.
Musschoot
et al, “
Conformality of Al2O3 and AlN deposited by plasma-enhanced atomic layer deposition
,”
J. Electrochem. Soc.
157
,
G111
(
2010
).
19.
S.
Moitzheim
,
J. E.
Balder
,
R.
Ritasola
et al, “
Toward 3D thin-film batteries: Optimal current-collector design and scalable fabrication of TiO2 thin-film electrodes
,”
ACS Appl. Energy Mater.
2
,
1774
1783
(
2019
).
20.
D.
Marinov
,
V.
Guerra
,
O.
Guaitella
,
J. P.
Booth
, and
A.
Rousseau
, “
Ozone kinetics in low-pressure discharges: Vibrationally excited ozone and molecule formation on surfaces
,”
Plasma Sources Sci. Technol.
22
,
055018
(
2013
).
21.
V.
Guerra
,
A.
Tejero-Del-Caz
,
C. D.
Pintassilgo
, and
L. L.
Alves
, “
Modelling N2–O2 plasmas: volume and surface kinetics
,”
Plasma Sources Sci. Technol.
28
,
073001
(
2019
).
22.
M.
Utriainen
,
K.
Saastamoinen
,
H.
Rekola
et al, “
Optical metrology 3D thin film conformality by LHAR chip assisted method
,”
Proc. SPIE
12008
,
119
126
(
2022
).
23.
V.
Cremers
,
R. L.
Puurunen
, and
J.
Dendooven
, “
Conformality in atomic layer deposition: Current status overview of analysis and modelling
,”
Appl. Phys. Rev.
6
,
021302
(
2019
).
24.
E. N.
Fuller
,
P. D.
Schettler
, and
J. C.
Giddings
, “
A new method for prediction of binary gas-phase diffusion coefficients
,”
Ind. Eng. Chem.
58
,
18
27
(
1966
).
25.
T. R.
Marrero
and
E. A.
Mason
, “
Gaseous diffusion coefficients
,”
J. Phys. Chem. Ref. Data
1
,
3
(
1972
).
26.
P.
Poodt
,
A.
Lankhorst
,
F.
Roozeboom
et al, “
High-speed spatial atomic-layer deposition of aluminum oxide layers for solar cell passivation
,”
Adv. Mater.
22
,
3564
3567
(
2010
).
27.
Y.
Creyghton
,
A.
Illiberi
,
A.
Mione
et al, “
Plasma-enhanced atmospheric-pressure spatial ALD of Al2O3 and ZrO2
,”
ECS Trans.
75
,
11
19
(
2016
).
28.
M. A.
Mione
,
V.
Vandalon
,
A.
Mameli
,
W. M. M.
Kessels
, and
F.
Roozeboom
, “
Atmospheric-pressure plasma-enhanced spatial ALD of SiO2 studied by gas-phase infrared and optical emission spectroscopy
,”
J. Phys. Chem. C
125
,
24945
24957
(
2021
).
29.
J. N.
Hilfiker
and
T.
Tiwald
, “
Dielectric function modeling
,”
Springer Ser. Opt. Sci.
212
,
115
153
(
2018
).

Supplementary Material