Uniformity and retention are crucial aspects for application of conductive bridge random access memory. In this letter, a self-aligned CuSiN interfacial layer was inserted into Cu/TaOx/Ru device to obtain a Cu/CuSiN/ TaOx/Ru structure. Compared with the Cu/TaOx/Ru device, the Cu/CuSiN/TaOx/Ru device shows much improved uniformity of resistance and programming voltage. Higher ON/ OFF ratio of $1000\times $ was observed, benefiting from the tight distribution of resistance. The standard deviation of set voltage was minimized from 0.635 to 0.187. Moreover, the low-resistance-state retention was also greatly improved. The uniformity and retention improvement could be well explained by the good controlment of cation injection and localization induced by CuSiN interfacial layer.