Self-aligned encapsulation hard mask to separate physically under-etched MTJ cells to reduce conductive R-deposition

A method comprising:

• forming a stack of magnetic tunneling junction (MTJ) layers over a bottom electrode;
• forming a top electrode layer on the stack of MTJ layers;
• patterning the top electrode layer;
• patterning a first portion of the stack of MTJ layers while using the patterned top electrode layer as a mask, wherein a second portion of the stack of MTJ layers covers a top surface of the bottom electrode after the patterning of the first portion of the stack of MTJ layers;
• forming an encapsulation layer directly on the patterned first portion of stack of MTJ layers and the second portion of the stack of MTJ layers;
• removing a portion of the encapsulation layer to thereby form a spacer on a sidewall of the patterned first portion of the stack of MTJ layers;
• and
• patterning the second portion of the stack of MTJ layers while using the spacer as a mask, wherein the patterning of the second portion of the stack of MTJ layers while using the spacer as the mask includes removing a first portion of the spacer to expose a sidewall surface of the patterned top electrode layer.

A magnetic tunneling junction (MTJ) structure comprising:

• a first MTJ cell disposed on a bottom electrode, the first MTJ cell including:
• a seed layer, a pinned layer, a barrier layer and a free layer, wherein the seed layer has a top surface facing away from the bottom electrode;
• a sidewall spacer disposed along and physically contacting sidewalls of the pinned layer, the barrier layer and the free layer, wherein the sidewall spacer extends to and physically contacts the top surface of the seed layer;
• and
• a top electrode disposed over and having a bottom surface facing the free layer, the bottom surface of the top electrode extending between opposing sidewalls of the top electrode and at least a portion of the opposing sidewalls of the top electrode being free of the sidewall spacer.