We study the dielectric properties ͑dielectric constant, loss and leakage current͒ of SiOC:H ͑silicon oxycarbide͒ thin films deposited by plasma-enhanced chemical vapor deposition from trimethylsilane ͑Dow Corning Z3MS gas precursor͒. The complex permittivity is studied from 0.01 Hz to 1 MHz as a function of temperature ͑room temperature to 115°C͒. The conductivity is studied as a function of the electric field, temperature, and time ͑current transients following application of bias͒. The films possess a low dielectric constant ͑around 2.8͒, which slightly decreases ͑from 2.88 to 2.82͒ when the frequency increases from 0.01 Hz to 1 MHz. The temperature dependence of the dielectric constant follows a Debye law ͑variation with 1/T, N 2 ϭ 4 ϫ 10 Ϫ32 C 2 m Ϫ1 , ϱ ϭ 2.46). Electronic, ionic, and dipolar polarizations contribute 0.93, 0.53, and 0.37 to the dielectric constant, respectively. The loss factor (Љ) is around 0.006 ͑dissipation factor tan ␦ ϭ 0.002). Application of a voltage step leads to current decays which persist up to at least 10 3 s. The current density is very low in these films ͑a few 10 Ϫ11 A/cm 2 at 1 MV/cm͒. Leakage currents are thermally activated ͑activation energy of 0.35 eV͒.

This article presents a study on Dow Corning® XLK™, an inorganic porous material with about 50% porosity and a dielectric constant of 2.0. It focuses on matters linked to sealing the porous film by depositing a plasma enhanced chemical vapor deposition (PECVD) dielectric cap layer. The study shows that the material can be modified during cap deposition due to the fast diffusion of reactants and radicals through the porous network, and acquire totally new properties which can be either beneficial or detrimental, depending on the chosen process. In particular, it is found that cap deposition processes on XLK in an oxidizing ambient, as used for SiO2 deposition, should be avoided. On the other hand, a beneficial modification of the dielectric film has been observed after SiC:H capping. It is also shown that there exists a critical thickness of capping material below which the cap layer reveals the presence of pinholes. The critical thickness value for a PECVD SiC:H cap layer on top of an XLK film is around 25 nm.

The semiconductor grade organosilicon gas trimethylsilane ͑Dow Corning Z3MS͒ can be used to deposit unique amorphous hydrogenated silicon carbide ͑␣-SiC:H͒-based alloy films that exhibit desirable properties such as chemical resistance, low stress, low permittivity, and low leakage. These film characteristics are ideal for applications in Cu-damascene interconnect technology. In this work, the results of a comprehensive study of Z3MS plasma enhanced chemical vapor deposition ͑PECVD͒ dielectric films are reported where all depositions were performed in commercial production PECVD equipment. Processing for ␣-SiC:H films deposited from Z3MS/He mixtures was optimized for deposition rate, uniformity, and permittivity. The processing parameters can be tuned for relative permittivity down to ϳ 4.2 making ␣-SiC:H an attractive substitute for PECVD silicon oxide or silicon nitride. Using mixtures of Z3MS and N 2 O precursors, ␣-SiCO:H films were deposited with very high deposition rates and film permittivity as low as ϳ 2.5. These films have been applied in damascene technology. Physical properties and stability of blanket films were studied. Measurement of relative permittivity, leakage current, and breakdown voltage was performed on metal/dielectric/metal structures. Fourier transform infrared, X-ray photoelectron, and high-energy ion scattering spectrometry were used to determine bonding and film compositions. Integration issues related to deep ultraviolet lithography, dry etch, strip, and metallization are discussed. Optimized film processes were integrated into 0.18 m Cu damascene interconnect process technology and the electrical results were compared to standard PECVD oxide. The results of these studies indicate that the device performance improvements inferred from the blanket film properties can be realized in fully integrated interconnect structures.

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