MTJ CD variation by HM trimming

A method comprising:

• forming a stack of magnetic tunneling junction (MTJ) layers;
• forming a first mask on the stack of MTJ layers;
• forming a second mask directly on the first mask such that the second mask physically contacts the first mask, the second mask being formed of a different material than the first mask;
• patterning the second mask and the first mask;
• trimming the patterned second mask and the patterned first mask;
• patterning the trimmed patterned second mask, the trimmed patterned first mask and at least one layer from the stack of MTJ layers, wherein the patterning of the trimmed patterned first mask reduces a roughness of an outer surface of the second mask.

A method comprising:

• forming a stack of magnetic tunneling junction (MTJ) layers;
• forming a conductive mask on the stack of MTJ layers;
• forming a dielectric mask on the conductive mask;
• patterning the dielectric mask and the conductive mask;
• trimming the patterned dielectric mask and the patterned conductive mask to reduce a roughness of an outer edge of the conductive mask;
• and
• patterning the trimmed patterned dielectric mask, the trimmed patterned conductive mask and at least one layer from the stack of MTJ layers, wherein the patterning of the trimmed patterned conductive mask further reduces the roughness of the outer edge of the conductive mask.