A semiconductor structure and fabrication method of forming a semiconductor structure. In the method there is provided an electrically conductive structure embedded in an interconnect dielectric material layer of a magnetoresistive random access memory device. A conductive landing pad is located on a surface of the electrically conductive structure. A multilayered magnetic tunnel junction (MTJ) structure and an MTJ cap layer is formed on the landing pad. Then there is formed a metal hardmask layer on a surface of said MTJ cap layer, the etch stop layer being subject to lithographic patterning and etching to form a patterned hardmask pillar structure. An encapsulating is performed to encapsulate, using an insulating material film, a top surface and sidewall surfaces of said patterned hardmask layer. Subsequent etch processing forms an MTJ stack having sidewalls aligned to the patterned hardmask without impacting MTJ stack performance.