A method is presented for constructing conductive bridging random access memory (CBRAM) stacks. The method includes forming a plurality of conductive lines within an interlayer dielectric (ILD), forming a CBRAM stack including at least an electrolyte layer, a conductive layer, a metal cap layer, and a top electrode such that a top end of the CBRAM stack has a smaller critical dimension than a bottom end of the CBRAM stack, forming a low-k dielectric layer over the CBRAM stack, and exposing a top surface of the CBRAM stack during a via opening.