Method of making sub-resolution pillar structures using undercutting technique

A method of making a device, comprising:

• forming an underlying mask layer over an underlying layer;
• forming a first mask layer over the underlying mask layer;
• patterning the first mask layer to form first mask features;
• undercutting the underlying mask layer to form underlying mask features using the first mask features as a mask;
• removing the first mask features;
• and
• patterning the underlying layer using at least the underlying mask features as a mask, wherein:
• the underlying mask layer comprises tungsten;
• and
• the first mask layer comprises a BARC layer, a DARC layer, a titanium nitride layer, or a combination thereof.

A method of making a device, comprising:

• forming an underlying mask layer over an underlying layer;
• forming a first mask layer over the underlying mask layer;
• patterning the first mask layer to form first mask features;
• undercutting the underlying mask layer to form underlying mask features using the first mask features as a mask;
• removing the first mask features;
• and
• patterning the underlying layer using at least the underlying mask features as a mask,
• wherein:
• the underlying layer is selected from the group consisting of an organic hard mask layer, an oxide hard mask layer, a device layer and combinations thereof;
• the device layer comprises at least one semiconductor layer;
• and
• the step of patterning the device layer forms an array of semiconductor pillars, wherein each semiconductor pillar comprises a diode, wherein the diode is a steering element of a memory cell, and wherein the memory cell further comprises a storage element.

A method of making a device, comprising:

• forming an underlying mask layer over an underlying layer;
• forming a first mask layer over the underlying mask layer;
• patterning the first mask layer to form first mask features;
• undercutting the underlying mask layer to form underlying mask features using the first mask features as a mask;
• forming filler features between the underlying mask features and over the underlying layer using the first mask features as a mask, wherein the filler features do not contact the underlying mask features;
• removing the first mask features;
• and
• patterning the underlying layer using at least a combination of the underlying mask features and filler features as a mask.

A method of making a device, comprising:

• forming an underlying mask layer over an underlying layer, wherein the underlying layer comprises a resistivity switching storage element layer and a bottom hard mask layer over the resistivity storage element layer;
• forming a first mask layer over the underlying mask layer;
• patterning the first mask layer to form first mask features;
• undercutting the underlying mask layer to form underlying mask features using the first mask features as a mask;
• removing the first mask features;
• etching the bottom hard mask layer using at least the underlying mask features as a mask to form first openings;
• filling the first openings with an insulating material;
• removing the underlying mask features;
• removing the bottom hard mask layer to form second openings exposing top of the resistivity switching storage element layer;
• and
• filling the second openings with at least one semiconductor material to form semiconductor diodes having a substantially pillar shape in the second openings.