Under-cut via electrode for sub 60nm etchless mram devices by decoupling the via etch process

A device, comprising:

• a bottom electrode;
• an undercut metal via disposed over the bottom electrode and comprising a first tapered sidewall and a second tapered sidewall;
• a first stack of magnetic tunneling junction (MTJ) layers disposed on the undercut metal via;
• a second stack of MTJ layers disposed over the bottom electrode and spaced apart from the first tapered sidewall along a direction;
• a third stack of MTJ layers disposed over the bottom electrode and spaced apart from the second tapered sidewall along the direction;
• a dielectric layer disposed over the bottom electrode, over the second stack of MTJ layers, and over the third stack of MTJ layers;
• and
• a top electrode disposed over the first stack of the MTJ layers and the dielectric layer,
• wherein the dielectric layer interfaces the first tapered sidewall and the second tapered sidewall of the undercut metal via.

A device, comprising:

• a bottom electrode;
• a conductive via disposed over the bottom electrode and comprising a tapered profile;
• a first magnetic tunneling junction (MTJ) stack disposed on the conductive via;
• a second MTJ stack disposed over the bottom electrode and spaced apart from a sidewall of the conductive via along a direction;
• a dielectric layer disposed over the bottom electrode, over the second MTJ stack, and along a sidewall of the first MTJ stack;
• and
• a top electrode disposed over and interfacing a top surface of the first MTJ stack and a top surface of the dielectric layer,
• wherein a portion of the dielectric layer extends between a sidewall of the conductive via and a sidewall of the second MTJ stack.