1. A method comprising: depositing a first electrode, a first metal cap, a first metal film, and a first hardmask (HM) on a silicon surface, wherein the deposited first metal film contains one or more crystal grains, wherein the one or more crystal grains in the first metal film contain a plurality of respective grain boundaries; increasing respective sizes of the plurality of respective grain boundaries in the one or more crystal grains in the first metal film by subtractive etching; forming a resistive random access memory (RRAM) cell, wherein the RRAM cell contains a critical dimension that is inversely proportional to a diameter of each respective crystal grains in the first metal film; depositing the RRAM cell over the deposited first electrode; depositing a second electrode, a second metal cap, a second metal film, and a second hardmask (HM) over the deposited RRAM cell, wherein the second metal film contains one or more crystal grains, wherein a diameter of each of the one or more crystal grains of the second film corresponds inversely to the critical dimension of the RRAM cell; and depositing a spacer over the second HM.