Sidewall image transfer on magnetic tunnel junction stack for magnetoresistive random-access memory patterning

A method of forming a semiconductor structure, comprising:

• forming a first spacer material over two or more mandrels disposed over a magnetoresistive random-access memory (MRAM) stack;
• performing a first sidewall image transfer of the two or more mandrels to form a first set of fins of the first spacer material over the MRAM stack;
• performing a second sidewall image transfer to form a plurality of pillars of the first spacer material over the MRAM stack;
• wherein the pillars of the first spacer material form top electrodes for a plurality of MRAM cells patterned from the MRAM stack;
• and
• further comprising:
• forming a first layer over the MRAM stack;
• forming a hard mask over the first layer;
• patterning a resist layer over the hard mask;
• and
• etching the hard mask and the first layer exposed by the resist layer to expose a top surface of the MRAM stack forming the two or more mandrels.

A method of forming a semiconductor structure, comprising:

• forming a first spacer material over two or more mandrels disposed over a magnetoresistive random-access memory (MRAM) stack;
• performing a first sidewall image transfer of the two or more mandrels to form a first set of fins of the first spacer material over the MRAM stack;
• and
• performing a second sidewall image transfer to form a plurality of pillars of the first spacer material over the MRAM stack;
• wherein the pillars of the first spacer material form top electrodes for a plurality of MRAM cells patterned from the MRAM stack;
• wherein performing the second sidewall image transfer comprises:
• depositing an organic polymer layer (OPL) over the first set of fins of the spacer material:
• depositing a hard mask layer over the OPL;
• patterning a second spacer material over the hard mask layer to form a second set of fins of the second spacer material;
• etching the second set of fins, and portions of the hard mask layer and the OPL exposed by the second set of fins to reveal a top surface of the MRAM stack in regions between the second set of fins;
• and
• stripping a remaining portion of the hard mask layer and the OPL;
• and
• wherein the first set of fins of the first spacer material are substantially perpendicular to the second set of fins of the second spacer material.