Densification of sol-gel thin films by ultraviolet and vacuum ultraviolet irradiations

Imai, Hiroaki; Awazu, Kunio; Yasumori, Masarux; Onuki, Hideo; Hirashima, Hiroshi

doi:10.1007/bf02436866

Cited by 18 publications

(13 citation statements)

References 16 publications

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“…For example, it has been reported that UV irradiation could increase the temperature of gel TiO 2 lms by less than 40 K. 27 Such an increase in temperature should however not be able to induce crystallization of the TiO 2 lm at room temperature. However, the present study is the rst demonstration of UV-induced crystallization of mesoporous materials.…”

Section: Methodsmentioning

confidence: 99%

UV/ozone-assisted low temperature preparation of mesoporous TiO₂with tunable phase composition and enhanced solar light photocatalytic activity

et al. 2014

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In this paper, we report a UV/ozone-assisted method for low temperature preparation of mesoporous TiO 2 with controlled crystalline phase. The results showed that the crystallization of mesoporous TiO 2 can occur at temperatures as low as 100 C under UV/ozone irradiation. Highly crystalline mesoporous anatase TiO 2 was obtained after UV/ozone treatment at 200 C. The phase transformation from anatase to rutile occurred during the UV/ozone treatment at 300 C and mesoporous bicrystalline TiO 2 with a controlled mixture of anatase and rutile phases was prepared by adjusting the exposure time. The photocatalytic performance of the mesoporous TiO 2 strongly depends on the crystal structures and the bicrystalline mesoporous TiO 2 exhibits remarkably enhanced solar light photocatalytic activity. This technique can be useful for low temperature preparation of crystalline mesoporous titania on various substrates and may be generalized to the synthesis of other materials.

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Section: Methodsmentioning

confidence: 99%

UV/ozone-assisted low temperature preparation of mesoporous TiO₂with tunable phase composition and enhanced solar light photocatalytic activity

et al. 2014

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“…Standard optical films of this material are widely used in aerospace applications. It is known from the literature [6][7][8][9] that the main effects of the UV irradiation on optical films are variations of thickness, chemical composition, structure, etc., all of them leading to changes in their optical properties. Bradford et al [6,8] found that the ultraviolet absorptance of silicon oxide films can be eliminated by UV irradiation and that the same UV treatment decreases their refractive index.…”

Section: Introductionmentioning

confidence: 99%

UV irradiation effects on TiO₂ thin films

Fernández-Rodrı́guez

Rico²,

González-Elipe³

et al. 2008

Phys. Status Solidi (c)

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This paper presents the behaviour of a standard optical coating to be used in aerospace applications when exposed to ultraviolet (UV) irradiation. Ellipsometric measurements are carried out in order to monitor the effects produced on the optical properties of the TiO2 film when it is exposed to a 500 W Xenon lamp during the time intervals of 1 hour, 22 hours and 42 hours. The ellipsometric measurements show that main changes occur in the real part of the refractive index after the first hour of exposure to UV irradiation. To assess a possible relation between the hydrophilicity that the UV irradiation typically induces on the TiO2 thin film, and the variation of the optical properties of the film, the water contact angle on the TiO2 optical coating was also measured after irradiation under similar conditions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…6) and led to a reduction in the Si-N-Si bonding angle. 29,30 In addition to analyzing film structure and measuring pore sizes, the porosity of the porous SiC x N y films generated after thermal annealing was quantified using XRR. Table I summarizes the pore morphology, porosity, and shrinkage results collected for the porous SiC x N y films.…”

Section: Ftir Analysis Of Sic X N Y /Porogen Hybrid and Porous Sic X N Ymentioning

confidence: 99%

Effect of Porogen Incorporation on Pore Morphology of Low-k SiC_xN_yFilms Prepared Using PECVD

Jeng

et al. 2014

ECS J. Solid State Sci. Technol.

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Low-k porous SiC x N y films were prepared through plasma-enhanced chemical vapor deposition, using 1,3,5-trimethyl-1,3,5-trivinylcyclotrisilazane (VSZ) as the matrix precursor and epoxycyclohexane (ECH) as a porogen. The effects of porogen loading and deposition temperature on porogen incorporation, pore morphology, and the properties of porous SiC x N y films were examined. In addition, the impact of film shrinkage and the corresponding nanopore structures after annealing were studied. The porosity of films deposited at 100 • C increased from 1.8% to 19.8% when ECH loading increased to 30%, above which the porosity remained nearly constant because of high film shrinkage. The pore size decreased slightly from 4.1 to 3.7 nm when ECH loading increased to 30%, above which the pores became larger and were broadly distributed. By contrast, increasing deposition temperature at 20% ECH loading decreased porogen incorporation and increased film density. The porosities and pore size of films decreased, respectively, when the deposition temperature increased. A short-range ordering of pores was observed only at low deposition temperatures because the N-Si-C cross-linked structures and organic phase were present. Optimized processing parameters facilitated the fabrication of low-k porous SiC x N y films exhibiting 19.8% porosity, 3.7-nm pores, a k value of 3.18, and an elastic modulus of 7. In CMOS backend interconnections, low-k etch-stop/dielectric barrier materials such as silicon carbonitride (SiC x N y ) (k = 4.5-5.5) and ultralow-dielectric-constant (ultralow-k, ULK) inter-layer dielectrics (ILDs) have been used to lower the effective capacitance (k eff ) in the 45 and 32 nm node and beyond.1 Silicon carbonitride films are typically prepared by performing plasma-enhanced chemical vapor deposition (PECVD) of multi-precursors such as silane/ammonia (or nitrogen)/methane 2,3 and trimethylsilane/amonia. 4 Recently, single source precursors such as hexamethyldisilazane 5 and BASICN 6 have been used for preparing dense low-k SiC x N y films by using PECVD because these films display low defects (i.e., low leakage current) and higher etch selectivity due to high C/Si ratio. 6 To further reduce the dielectric constant of silicon carbonitride film, incorporation of porosity is one of the primary approaches, in addition to continued addition of elements with lower polarizability such as more C atoms.A conservative approach was proposed by Nguyen et al., 7 who prepared a dielectric barrier bilayer of dense SiN y /porous SiC x N y , exhibiting 12% porosity, by performing plasma deposition of dimethylsilacyclopentane and NH 3 and then using UV to cure the samples. The dense films of the bilayer on top helped protect the underlying copper layer against plasma-induced damage and oxidation caused by the diffusion of oxygen, whereas the bottom porous film of the bilayer contributed to a reduction in the dielectric constant.8 Because they possess a bilayer (dense film/porous film) or sandwich (dense film/porous film/dense film) ...

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Densification of sol-gel thin films by ultraviolet and vacuum ultraviolet irradiations

Cited by 18 publications

References 16 publications

UV/ozone-assisted low temperature preparation of mesoporous TiO₂with tunable phase composition and enhanced solar light photocatalytic activity

UV/ozone-assisted low temperature preparation of mesoporous TiO₂with tunable phase composition and enhanced solar light photocatalytic activity

UV irradiation effects on TiO₂ thin films

Effect of Porogen Incorporation on Pore Morphology of Low-k SiC_xN_yFilms Prepared Using PECVD

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Densification of sol-gel thin films by ultraviolet and vacuum ultraviolet irradiations

Cited by 18 publications

References 16 publications

UV/ozone-assisted low temperature preparation of mesoporous TiO2with tunable phase composition and enhanced solar light photocatalytic activity

UV/ozone-assisted low temperature preparation of mesoporous TiO2with tunable phase composition and enhanced solar light photocatalytic activity

UV irradiation effects on TiO2 thin films

Effect of Porogen Incorporation on Pore Morphology of Low-k SiCxNyFilms Prepared Using PECVD

Contact Info

Product

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UV/ozone-assisted low temperature preparation of mesoporous TiO₂with tunable phase composition and enhanced solar light photocatalytic activity

UV/ozone-assisted low temperature preparation of mesoporous TiO₂with tunable phase composition and enhanced solar light photocatalytic activity

UV irradiation effects on TiO₂ thin films

Effect of Porogen Incorporation on Pore Morphology of Low-k SiC_xN_yFilms Prepared Using PECVD