Lower operation current and voltage are strongly required for scaled RRAM devices with high density memory cell arrays. As the lower operation current reduces the size of the conductive filament, stable high speed endurance performance of RRAM device becomes a challenging issue. In this work, for the first time, we demonstrate 1μA, +/-1V bipolar switching and a 100x reduction of the high-resistance-state current for TiN/HfO _x /Zr/W RRAM devices. This was achieved by identifying key parameters which allot for superior control over the conductive filament formation. We also identify the trade-off between reduced operative power and the switching pulse width, while demonstrating high switching performance up to 10 cycles at an operation current of 20μA and a pulse width of 200 ns.