Dual-mode microwave/radiofrequency PECVD processes have been used for the fabrication of four types of amorphous dielectric films: SiN/sub 1.3/, SiO/sub 2/, a-C:H, and plasma-polymerized hexamethyldisiloxane (PP-HMDSO). For each of these materials, we have determined values of the critical average ion energy E~/sub i/ (between about 70 and 170 eV) and of the critical ion flux, which characterize the transition from a porous to a densely packed microstructure, at low (/spl sim/25/spl deg/C) substrate temperature T/sub s/ and high deposition rates (between 20 and 120 /spl Aring//s). When E~/sub i/ values are optimized, the d.c. resistivity and the dielectric loss tangent values for all of these dielectrics are found to be about 10/sup 16/ /spl Omega/ cm and 10/sup -3/, respectively. We present evidence which shows that E~/sub i/ and T/sub s/ can be considered as interchangeable process parameters. Large area scale-up and continuous deposition onto flexible substrate materials are also discussed. >