A systematic investigation of the influence of the process parameters temperature, pressure, total gas flow, and SiH 2 Cl 2 :NH 3 gas flow ratio on the residual stress, the refractive index, and its nonuniformity across a wafer, the growth rate, the film thickness nonuniformity across a wafer, and the Si/N incorporation ratio of low pressure chemical vapor deposition Si x N y films has been performed. As a tool for complete characterization of the property-deposition parameter relations, a full factorial experimental design was used to determine the dominant process parameters and their interactions. From this study it could be concluded that, in decreasing order of importance, the gas flow ratio of Si and N containing precursors, temperature, and pressure are the most relevant parameters determining the mechanical and optical properties of the films and the deposition rate and nonuniformity in film properties across a wafer. The established relations between properties and deposition parameters were fitted with physical-chemical models, including a film growth model based on a Freundlich adsorption isotherm. The optimal deposition conditions for films to be used in micromechanical devices will be discussed.

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Stress in hard films is the net sum of tensile stress generated at the grain boundaries, compressive stress due to ion peening, and thermal stress due to the difference in thermal expansion of the coating and substrate. The tensile part due to grain boundaries is thickness dependent. The other two contributions are not thickness dependent. Summation of the three components leads to a stress gradient in the coating. In the present paper it is demonstrated that adding the three contributions mentioned above yields a good description of the observed dependence of stress on thickness in CrN coatings.

Closely spaced, through-wafer interconnects are of large interest in RF MEMS and MEMS packaging. In this paper, a suitable technique to realize large arrays of small size through-wafer holes is presented. This approach is based on macroporous silicon formation in combination with wafer thinning. Very high aspect ratio (2 100) structures are realized. The wafers containing the large arrays of 2-3pm wide holes are thinned down to 200-150pm by lapping and polishing. Copper electroplating is finally employed to realize arrays ofhigh aspect ratio Cu plugs.

The injection of interstitials during annealing of nonamorphizing Si implants has been monitored by means of sharp boron-doped marker layers grown by reduced pressure chemical vapor deposition. The boron diffusivity enhancement measured during the initial annealing stages (t<15 s) at 700 °C is at least an order of magnitude larger than the enhancement during subsequent annealing. The high supersaturation of interstitials during the early stages of the anneal induces immobilization of boron down to concentrations of ≊1×1017 cm−3, consistent with interstitial-driven boron clustering. The ultrafast diffusion sets lower limits for the silicon and boron interstitial diffusivities at 700 °C of 2×10−10 cm2 s−1 and 2×10−13 cm2 s−1, respectively.