This work reports the development of a resistive random-access memory (RRAM) device with Silicon-oxide (SiOx) active switching material.  Metal-oxide based RRAM synaptic devices typically suffer from high variability and strongly non-linear conductance change. In this work, we demonstrate a SiOx-based synapse with low operating voltages, excellent uniformity in the switching operation, and analog tunability of conductance. The devices also exhibit linear and symmetric conductance update. Our investigations reveal that the enhanced uniformity and analog tunability can be attributed to an interfacial switching mechanism which can be controlled through careful optimization of the device operating conditions.