Kohei Kawamura

Diagnostics of hydrogen role in the Si surface reaction processes employing in-situ Fourier transform infrared-attenuated total reflection

The oxidation process of H-terminated amorphous Si film on Ge and the reaction mechanism of the triethylsilane (TES)/H system which allows us to deposit an organic Si film conformably have been investigated employing in-situ FTIR(Fourier transform infra red)-ATR(attenuated total reflection). This measurement was demonstrated to be a sensitive and simple method to inspect the role of H(hydrogen) in their surface reactions. In the Si oxidation case, the H-terminated Si is readily oxidized by O(oxygen) atoms. The oxidation with O2 molecules proceeds gradually as the breaking of Si-H bonds and forming of H-Si-O bonds due to binding of O atoms with the back bond of Si for 700 min. After about 700 min, dissociated O atoms rapidly penetrate the Si film, and oxidize the bulk Si, leaving both Si-H and H-Si-O bonds still on the Si surface. Next, in the TES/H reaction system, gas phase FTIR spectra obtained by reactions of H atoms or H2 molecules with TES do not show appreciable change in a wide range of pressure. Nevertheless, in-situ FTIR-ATR reveals that TES reacts easily with H atoms on the surface, desorbing H2, methyl and ethyl groups.

Robust Ultralow-k Dielectric (Fluorocarbon) Deposition by Microwave Plasma-Enhanced Chemical Vapor Deposition

A robust fluorocarbon film was successfully deposited on a substrate at a temperature above 400 °C by the new microwave plasma-enhanced chemical vapor deposition (MWPE-CVD) method using the linear C5F8 precursor instead of a conventional cyclic C5F8 one. The fluorocarbon performed keeping the dielectric constant low as a value of 2.25 by controlling the molecular structure forming cross-linked poly(tetrafluoroethylene) (PTFE) chains with configurational carbon atoms. The novel fluorocarbon demonstrates less fluorine degassing at an elevated temperature, with high mechanical strength and without degradation of adhesion of the fluorocarbon film to SiCN and SiOx stacked films after thermal stress at 400 °C and 1 atm N2 for 1 h. Consequently, this robust fluorocarbon film is considered a promising candidate for general porous silicon materials with applications to practical integration processes as an interlayer dielectric.