Self-aligned etching techniques for memory formation

A method, comprising:

• forming, above a substrate, a stack of alternating materials and a pillar extending away from the substrate and through the stack of alternating materials, wherein the stack of alternating materials and the pillar form a plurality of memory cells;
• forming, above the pillar, a polysilicon material extending away from the pillar and through the stack of alternating materials, wherein the polysilicon material has a first width;
• forming a masking material above the polysilicon material and the stack of alternating materials, wherein the masking material is aligned with the polysilicon material and has a second width that is greater than the first width;
• and
• removing a first portion of the stack of alternating materials to form a trench used to divide the plurality of memory cells into subblocks, wherein the masking material prevents a second portion of the stack of alternating materials beneath the masking material from being removed with the first portion.

A method, comprising:

• forming, above a substrate, a stack of alternating materials;
• forming, above the substrate, a first pillar and a second pillar each extending away from the substrate and through the stack of alternating materials, wherein the stack of alternating materials and the first pillar form a first plurality of memory cells, and wherein the stack of alternating materials and the second pillar form a second plurality of memory cells;
• forming, above the first pillar, a first polysilicon material extending away from the first pillar and through the stack of alternating materials, wherein the first polysilicon material has a first width;
• forming, above the second pillar, a second polysilicon material extending away from the second pillar and through the stack of alternating materials, wherein the second polysilicon material has a second width;
• forming a first masking material above the first polysilicon material and the stack of alternating materials, wherein the first masking material is aligned with the first polysilicon material and has a third width that is greater than the first width;
• forming a second masking material above the second polysilicon material and the stack of alternating materials, wherein the second masking material is aligned with the second polysilicon material and has a fourth width that is greater than the second width;
• and
• removing a first portion of the stack of alternating materials to form a trench used to divide the first plurality of memory cells and the second plurality of memory cells into subblocks, wherein the first masking material prevents a second portion of the stack of alternating materials beneath the first masking material from being removed with the first portion and the second masking material prevents a third portion of the stack of alternating materials beneath the second masking material from being removed with the first portion.

A method, comprising:

• forming, above a substrate, a stack of alternating materials and a pillar extending away from the substrate and through the stack of alternating materials;
• forming, above the pillar, a polysilicon material extending away from the pillar and through the stack of alternating materials, wherein the polysilicon material terminates before a top surface of the stack of alternating materials that is opposite the substrate;
• and
• forming a nitride material above the polysilicon material and the stack of alternating materials, wherein the nitride material is aligned with the polysilicon material.