Hexamethyldisilazane was plasma polymerised on silicon wafers and on glass and quartz substrates, in order to obtain films with high concentration of CH3 radicals. Two plasma reactors were used: a capacitive 40 kHz reactor and an inductive 13.56 MHz reactor. Very high deposition rates (up to 700nm/min), evaluated by profilometry, were obtained using the low frequency capacitive reactor, with much lower rates obtained at 13.56 MHz (capacitive and inductive coupling). The refractive indexes, measured by ellypsometry, were close to 1.6 (40 kHz capacitive reactor), and near 1.5 (13.56 MHz inductive reactor). Infrared analysis showed Si-CH3 and mainly Si-N-Si -Si or Si-CH2 bonds for the low frequency and inductively coupled reactors, respectively. Addition of nitrogen to the plasma did not lead to variations in the infrared spectra, but increased the chemical resistance of the film, probably due to cross-linking. Addition of oxygen resulted in the decrease of Si-N-Si bonds compared to Si-CH2-Si and loss of Si-CH3 in both reactors. The oxygen addition also did not improve chemical resistance and prevented the adhesion of photoresists to glass. Raman spectroscopy revealed the presence of CHn bonds only. Contact angle measurements showed that these films are highly hydrophobic, and have high affinity to organic solvents, both polar and non-polar. They also have good chemical resistance to strong acid and basic solutions. The films were tested for the following applications: as an adhesion promoter of photoresists on glass substrates, as a defrosting protective layer, as an ultraviolet radiation protective layer, and as an adsorption coating in microstructures, using silicon or porous silicon as substrates. In all applications, the films obtained with hexamethyldisilazane in the low frequency reactor presented better results than the ones obtained with the inductive reactor.
