Chemical Structure, Optical and Dielectric Properties of PECVD SiCN Films Obtained from Novel Precursor

Abstract

A phenyl derivative of hexamethyldisilazane—bis(trimethylsilyl)phenylamine—was first examined as a single-source precursor for SiCN film preparation by plasma enhanced chemical vapor deposition. The use of mild plasma (20 W) conditions allowed the preparation of highly hydrogenated polymeric-like films. The synthesis was carried out under an inert He atmosphere or under that of NH3 with the deposition temperature range from 100 to 400 °C. The chemical bonding structure and elemental composition were characterized by Fourier-transform infrared spectroscopy, energy-dispersive X-ray analysis and X-ray photoelectron spectroscopy. The surface morphology was investigated by scanning electron microscopy. Ellipsometric porosimetry, a unique high-precision technique to investigate the porosity of thin films, was applied to examine the porosity of SiCN samples. The films were found to possess a morphologically homogenous dense defect-free structure with a porosity of 2–3 vol.%. SiCN films were studied in terms of their optical and dielectric properties. Depending on the deposition conditions the refractive index ranged from 1.53 to 1.78. The optical bandgap obtained using UV-Vis spectroscopy data varied from 2.7 eV for highly hydrogenated polymeric-like film to 4.7 eV for cross-linked nitrogen-rich film. The dielectric constant was found to decrease from 3.51 to 2.99 with the rise of hydrocarbon groups’ content. The results obtained in this study were compared to the literature data to understand the influence of precursor design to the optical and electrical properties of the films.

Controlling of Chemical Bonding Structure, Wettability, Optical Characteristics of SiCN:H (SiC:H) Films Produced by PECVD Using Tetramethylsilane and Ammonia Mixture

“…The related parameter of optical bandgap demonstrated a stepwise increase from 3.3 eV to 5.0 eV at NH 3 /TMS = 0.6. Such a behavior was observed previously in several publications for SiCN films produced using different precursors [14,[57][58][59]. The main reason can be a change of chemical binding structure.…”

“…The variety of organosilicon precursors includes commercially available compounds, such as tetramethylsilane [5][6][7], hexamethyldisilazane [8,9], and tetramethyldisilazane [10,11]. The novel substances of organosilanes, silazanes, aminosilazanes or carbodiimides, such as hexamethylcyclotrisilazane [12], bis(trimethylsilyl)ethylamine [13], bis(trimethylsilyl)phenylamine [14], 1,3-bis(dimethylsilyl)-2,2,4,4-tetramethylcyclodisilazane [12], N-methyl-aza-2.2.4-trimethylsilacyclopentane [15], and bis(tetramethylguanidine)dimethylsilane [16], (dimethylamino)dimethylsilane [17], tris (dimethylamino)silane [17], bis(dimethylamino)methylsilane [18], methyltris(diethylamino) silane [19], tris(diethylamino)silane [20], and tris(dimethylamino)silane [21], bis(trimethylsilyl) carbodiimide [22] and dimethyl(2,2-dimethylhydrazino)silane [23], are also regarded as potential precursors for silicon carbonitride film synthesis for different applications. In the review [24], we considered the relationship between the structure of the precursor molecule and the nature of the bonds present in the films deposited with its participation.…”

Enhanced Wettability, Hardness, and Tunable Optical Properties of SiCxNy Coatings Formed by Reactive Magnetron Sputtering

“…It should be noted that the band gap of hydrogenated SiC x N y :H layers deposited using MS and complex gas mixtures of nitrogen and argon with hydrogen [ 29 ], methane [ 20 ], and acetylene [ 19 , 31 ] or obtained at a higher synthesis temperature [ 18 ], has a higher value and reaches 3.8 eV. In fact, hydrogenated SiC x N y :H films obtained by plasma enhanced chemical vapor deposition method can exhibit larger values of E g = 4.7 eV [ 66 ].…”

1,4-Bis(trimethylsilyl)piperazine—Thermal Properties and Application as CVD Precursor

“…The values of the refractive index obtained in this study are typical for PECVD SiCN films produced using organosilicon precursors. For comparison, the values of the refractive index of the SiCN films produced by RF PECVD from hexamethyldisilazane were 1.7-2.1 [61], the atmospheric pressure CVD from tetramethyldisilazane was 1.45-1.95 [62], the PECVD from the tetramethylsilane and ammonia mixture was 1.57-1.90 [63], the PECVD from bis(trimethylsilyl)phenylamine was 1.53-1.78 [64] and the PECVD from 1,3-divinyl-1,1,3,3tetramethyldisilazane was 1.51-1.90 [65]. The refractive indices for the films prepared by PVD methods and CVD using simple gas mixtures differed: the ECR PECVD from the CH 4 /N 2 /SiH 4 gas mixture was 1.95-2.08 [66], the MW-CVD from the CH 4 /NH 3 /H 2 /SiH 4 gas mixture was 2.00-2.17 [67] and the magnetron sputtering was 2.0-2.4 [68].…”