A silicon-based showerhead electrode is provided where backside inserts are positioned in backside recesses formed along the backside of the electrode. The backside inserts comprise a threaded outside diameter, a threaded inside diameter, and a tool engaging portion formed in the threaded inside diameter. The tool engaging portion is formed such that the backside insert further comprises one or more lateral shielding portions between the tool engaging portion and the threaded outside diameter to prevent a tool engaged with the tool engaging portion of the backside insert from extending beyond the threaded outside diameter of the insert. Further, the tool engaging portion of the backside insert comprises a plurality of torque-receiving slots arranged about the axis of rotation of the backside insert. The torque-receiving slots are arranged to avoid on-axis rotation of the backside insert via opposing pairs of torque receiving slots.