Critical properties and charge transport in ethylene bridged organosilica low-κ dielectrics

• Published in: Journal of applied physics 2020-05, Vol.127 (19)
• Main Authors: Perevalov, Timofey V., Gismatulin, Andrei A., Seregin, Dmitry S., Wang, Yingjie, Xu, Haoyu, Kruchinin, Vladimir N., Spesivcev, Evgeniy V., Gritsenko, Vladimir A., Nasyrov, Kamil’ A., Prosvirin, Igor’ P., Zhang, Jing, Vorotilov, Konstantin A., Baklanov, Mikhail R.
• Format: Article
• Language: English
• Subjects: Applied physics; Charge transport; Chemical composition; Current carriers; Current voltage characteristics; Dielectric properties; Electron energy loss spectroscopy; Electron tunneling; Ellipsometry; Energy dissipation; Ethane; Ethylene; Fourier transforms; Photoelectrons; Porosity; Qualitative analysis; Silicon; Space charge; Spectrum analysis
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.5145239

Organosilicate-glass-based low-κ films containing both terminal methyl groups and an ethylene bridge between the silicon atoms are spin-on deposited by using 1,2-bis(trimethoxysilyl)ethane and methyltrimethoxysilane, Brij30 template, and thermal curing. The chemical composition, porosity, and internal defects are studied using Fourier-transform infrared spectroscopy, x-ray photoelectron spectroscopy, electron energy loss spectroscopy, UV induced luminescence, and ellipsometric porosimetry. It was found that the studied films contain oxygen-deficient centers (Si—Si bonds). The high defect density of the states near the valence-band edge of the studied low-κ films leads to a relatively small bandgap value of about 6.3 eV. The current–voltage characteristics at different temperatures were analyzed using six theoretical charge transport models where the transport is limited by the traps ionization. It was found that the best qualitative and quantitative agreement between the calculations and experimental data is achieved by using the model of phonon-assisted electron tunneling between the neutral traps and is supplemented by considering the space charge and charge carrier kinetics. Since the thermal and optical energies of the traps in the studied films are 1.6 eV and 3.2 eV, respectively, it is concluded that the traps are responsible for the charge transport in the Si—Si bonds.