[en] Si-based resistive random access memory (RRAM) devices at the nanoscale with high uniformity have great potential applications in the future. We demonstrate that the uniformity evolution of the a-SiN_x:H RRAM at the low resistance state (LRS) and the high resistance state (HRS) can be clearly monitored by presetting a Si dangling bond (Si-DB) conductive pathway through thermal energy. It is found that the increased magnitude of uniformity for the LRS and the HRS are determined by the number of preset Si-DBs, which can be controlled by tuning thermal energy. As for LRS, the Si-DBs produced under the electric field along with the preset Si-DB conductive pathways form the main conductive pathway. Theoretical calculation of current–voltage (I–V) curves indicates that the Si-DB conductive pathways obey the trap-assisted tunneling model. In the HRS, the preset Si-DBs induced by thermal energy are the unique source of the conductive pathway. The transmission mechanism involves a trap-to-trap process by the hopping of electrons under a low electric field, Poole–Frenkel emission in the main region under the medium electric field and Fowler–Nordheim tunneling under the high electric field. Our discovery of the uniformity evolution for a-SiN_x:H RRAM device through presetting the Si-DB conductive pathway provides new insight into the resistive switching mechanism of next generation Si-based RRAM devices. (paper)