Frequency effects and properties of plasma deposited fluorinated silicon nitride
The properties of low-hydrogen, fluorinated plasma-enhanced chemical vapor deposition (PECVD) silicon nitride films grown using NF/sub 3//SiH/sub 4//N/sub 2/ feed mixtures in 200 kHz and 14 MHz discharges were compared. High-energy ion bombardment at 200 kHz is expected to enhance surface diffusion and chemical reconstruction. Compared to fluorinated silicon nitride deposited at 14 MHz under otherwise comparable conditions, the 200 kHz films had a lower Si--H bond concentration (approx. <1 x 10/sup 21/ cm/sup -3/), lower total hydrogen content (5--8 x 10/sup 21/ cm/sup -3/), better resistance to oxidation, lower compressive stress (-0.7 to -1.5 Gdyne/cm), and higher density (3.1 g/cm/sup 3/). The dielectric constant of better low-frequency Class I films was constant to 500 MHz, while that of high-frequency films fell up to 15% between 100 Hz and 10 MHz. The absorption edges of low-frequency PECVD fluorinated silicon nitride films were between 5.0 and 6.1 eV, which compare with 4.4 to 5.6 eV for the high-excitation frequency fluorinated material and 3 to 4 eV for conventional PECVD nitride. However high-frequency films may have fewer trap centers and a lower dielectric constant. 14 MHz p-SiN:F films grown with NH/sub 3/ as an auxiliary nitrogen source showed absorption edges similar to low-frequency material grown from NF/sub 3//SiH/sub 4//N/sub 2/, but they have substantially more N--H bonding. The dielectric constant and absorption edge of these films were comparable to those of low-frequency p-SiN:F from NF/sub 3//SiH/sub 4//N/sub 2/.
- Research Organization:
- ATandT Bell Laboratories, Murray Hill, New Jersey 07974
- OSTI ID:
- 5451145
- Journal Information:
- J. Vac. Sci. Technol., B; (United States), Vol. 6:2
- Country of Publication:
- United States
- Language:
- English
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