101. PE-CVD of Fluorocarbon/SiO Composite Thin Films Using C4F8 and HMDSO.
- Author
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Shirafuji, Tatsuru, Miyazaki, Yasuo, Hayashi, Yasuaki, and Nishino, Shigehiro
- Abstract
Plasma copolymerization of hexamethyldisiloxane (HMDSO,(CH
3 )3 -Si-O-Si-(CH3 )3 ) and C4 F8 was performed using an RF plasma enhanced chemical vapor deposition method for application to low dielectric constant intermetal dielectrics. Structure of the films was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The film composition was controlled gradually from fluorinated carbon to organic siloxane by changing the mixing ratio of HMDSO/Ar. Dielectric constant of the films ranged from 2–3.3. Thermal stability of the films, which was characterized by intensity loss of IR absorbance peak around 1000–1500 cm−1 corresponding to C-Fn , Si-O-Si and Si-(CH2 )n -Si bonds, was inferior to that from C2 F4 /HMDSO/Ar. In situ gasphase FT-IR spectroscopy revealed that there was a marked difference between the gas phase of C4 F8 /HMDSO/Ar and that of C2 F4 /HMDSO/Ar discharges. The IR spectrum of the former combination plasma contained a peak at 1250 cm−1 with full width at half maximum as large as 150 cm−1 , which suggests that fluorocarbon particles and/or dusts are formed in the plasma. This suggests also that deposition precursors are not only CFn ( n = 1, 2, and 3) but also larger precursors such as Cx Fy ( x > 1, y < 2 x + 2) in C4 F8 /HMDSO/Ar discharges, which is presumably the cause of difference in thermal stability of the films prepared from C4 F8 /HMDSO/Ar and C2 F4 /HMDSO/Ar mixtures. [ABSTRACT FROM AUTHOR]- Published
- 1999
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