Abstract:The authors report a superconformal chemical vapor deposition method that affords bottom-up filling of trenches with oxide: the film growth rate increases with depth such that the profile of material develops a “V” shape that fills in along the centerline without a seam of low density material. The method utilizes low pressures of a metal precursor plus a forward-directed flux of co-reactant (water) at a lower pressure than the precursor. Under these conditions, many of the co-reactant molecules travel ballist… Show more
“…1a . The seams and voids are unavoidable critical defects formed during nanofabrication; they degrade device performance, electrical conductivity and thermal or mechanical properties 14 – 16 . To avoid seam formation, anisotropic growth inside the structure, like V-shaped growth, is required but cannot be achieved from the isotropic growth during ALD (Fig.…”
Section: Introductionmentioning
confidence: 99%
“…To avoid seam formation, anisotropic growth inside the structure, like V-shaped growth, is required but cannot be achieved from the isotropic growth during ALD (Fig. 1b ) 14 . Fig.…”
The integration of bottom-up fabrication techniques and top-down methods can overcome current limits in nanofabrication. For such integration, we propose a gradient area-selective deposition using atomic layer deposition to overcome the inherent limitation of 3D nanofabrication and demonstrate the applicability of the proposed method toward large-scale production of materials. Cp(CH3)5Ti(OMe)3 is used as a molecular surface inhibitor to prevent the growth of TiO2 film in the next atomic layer deposition process. Cp(CH3)5Ti(OMe)3 adsorption was controlled gradually in a 3D nanoscale hole to achieve gradient TiO2 growth. This resulted in the formation of perfectly seamless TiO2 films with a high-aspect-ratio hole structure. The experimental results were consistent with theoretical calculations based on density functional theory, Monte Carlo simulation, and the Johnson-Mehl-Avrami-Kolmogorov model. Since the gradient area-selective deposition TiO2 film formation is based on the fundamentals of molecular chemical and physical behaviours, this approach can be applied to other material systems in atomic layer deposition.
“…1a . The seams and voids are unavoidable critical defects formed during nanofabrication; they degrade device performance, electrical conductivity and thermal or mechanical properties 14 – 16 . To avoid seam formation, anisotropic growth inside the structure, like V-shaped growth, is required but cannot be achieved from the isotropic growth during ALD (Fig.…”
Section: Introductionmentioning
confidence: 99%
“…To avoid seam formation, anisotropic growth inside the structure, like V-shaped growth, is required but cannot be achieved from the isotropic growth during ALD (Fig. 1b ) 14 . Fig.…”
The integration of bottom-up fabrication techniques and top-down methods can overcome current limits in nanofabrication. For such integration, we propose a gradient area-selective deposition using atomic layer deposition to overcome the inherent limitation of 3D nanofabrication and demonstrate the applicability of the proposed method toward large-scale production of materials. Cp(CH3)5Ti(OMe)3 is used as a molecular surface inhibitor to prevent the growth of TiO2 film in the next atomic layer deposition process. Cp(CH3)5Ti(OMe)3 adsorption was controlled gradually in a 3D nanoscale hole to achieve gradient TiO2 growth. This resulted in the formation of perfectly seamless TiO2 films with a high-aspect-ratio hole structure. The experimental results were consistent with theoretical calculations based on density functional theory, Monte Carlo simulation, and the Johnson-Mehl-Avrami-Kolmogorov model. Since the gradient area-selective deposition TiO2 film formation is based on the fundamentals of molecular chemical and physical behaviours, this approach can be applied to other material systems in atomic layer deposition.
“…The obtained results demonstrate that SLs facilitate the development of new CVD processes with superior conformality onto high-AR 3D features. To achieve even higher conformality, SLs can be combined with other strategies for conformal CVDs ,,,− ,− including utilization of surface inhibitors − and quasi zeroth-order reaction kinetics, , which are summarized in Table . Furthermore, the use of SLs is not limited to CVD; it can also be applied to other deposition techniques (e.g., ALD) involving multiple film-forming species where η values vary by several orders of magnitude.…”
We propose a new, concise method
for conformal chemical vapor deposition
(CVD) using sacrificial layers (SLs) to fill three-dimensional features
with microscopic pores. SLs are porous membranes (e.g., ceramic felts)
that filter film-forming species having high sticking-probability
(η). CVD processes with multiple film-forming species generally
suffer from poor conformality due to preferential film deposition
at the inlets of features by the high-η species, such as reactive
intermediates. An SL traps such high-η species before they reach
the target features and selectively supplies film-forming species
with lower η (e.g., source precursors or stable intermediates)
that enables conformal film deposition. Here the trapping efficiency
of an SL was predicted and a procedure for designing an optimal SL
was established. The procedure was demonstrated by CVD of silicon
carbide (SiC) with multiple film-forming species of high-η species
(η = 8.0 × 10–3) and lower-η species
(η = 5.9 × 10–5 and 2.2 × 10–7). The trapping of 99.2% of incident high-η
species was achieved with an optimized SL, wherein the deposition
rate (m/s) contribution by high-η species declined from 0.546
at the SL inlet to 0.014 at its outlet. Finally, using these optimized
SLs, SiC-CVD filling of micron-scale trenches was demonstrated with
an aspect-ratio of 16:1.
“…Continuous CVD processes can be tuned to yield conformal deposition and even super-conformal deposition in some conditions. 22,23 Abelson and Girolami describes how a high degree of conformal coverage in continuous CVD can be achieved by reducing the surface reaction probability, β, defined as the ratio of the number of precursor molecules that stick to the surface to the total number of incoming molecules. A lower value of β means that the molecules arriving at the surface are more probable to be re-emitted to the gas phase rather than being chemisorbed.…”
We report conformal chemical vapor deposition (CVD) of boron carbide thin films on silicon substrates with 8:1 aspect-ratio morphologies, using triethylboron (TEB, B(C2H5)3) as single source CVD precursor. Step coverage (SC) calculated from the cross-sectional scanning electron microscopy measurements shows that films deposited at ≤450 °C were perfectly conformal (SC = 1). We attribute this to the low reaction probability at low substrate temperatures enabling more gas phase diffusion into the features. The chemical state of the material, determined by X-ray photoelectron spectroscopy, shows as carbide with B-B, B-C, C-B and C-C chemical bonds. Quantitative analysis by time-of-flight elastic recoil detection analysis reveals that films deposited at 450 °C are boron-rich with around 82.5 at.% B, 15.6 at.% C, 1.3 at.% O and 0.6 at.% H, i.e., about B5C. The film density as measured by X-ray reflectometry, varies from 1.9 to 2.28 g/cm3 depending on deposition temperature.
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