The purpose of this paper is to discuss the results of experiments that were done to develop a process to reliably produce low-stress a-SixC1−x:H films by PECVD. The films were deposited at 380 °C in a horizontal hot wall reactor using mixtures of silane and methane. The unique feature of the reactor is that, In contrast to others, the plasma was powered by two power sources; one was operated at 450 kHz, the other at 13.56 MHz. The plasma was maintaired in a mixed frequency mode during deposition. The total energy input to the plasma during a duty cycle was kept fixed while the properties of the films were altered by adjusting the relative energy output of each power supply. The energy output of each generator was adjusted by changing their on-times and peak powers. The composition of the films, their Initial stress, and the behavior of their stress during a temperature anneal were studied extensively. The Si/C ratio of the films varied from 0.3 to 3.0. The hydrogen concentration varied from 24 to 32 atomic percent. The initial stress was controlled by frequency mixing, and varied from −400 MPa to + 100 MPa.