Wordline contact formation in NAND devices

A method of forming a three-dimensional NAND structure, the method comprising:

• providing a stack of layers comprising a plurality of wordlines separated by a plurality of insulating layers;
• forming a plurality of trenches in the stack of layers, wherein each of the plurality of trenches includes a tiered sidewall and a bottom surface, wherein a first trench of the plurality of trenches is formed to a first depth relative to a top surface of the stack of layers, wherein a second trench of the plurality of trenches is formed to a second depth relative to the top surface of the stack of layers, and wherein the second depth is greater than the first depth;
• and
• forming a liner within each of the plurality of trenches, wherein the liner is deposited at a non-zero angle of inclination relative to a normal extending perpendicular from the top surface of the stack of layers, wherein the liner has a first thickness along the tiered sidewall of the first trench, wherein the liner has a second thickness along the tiered sidewall of the second trench, wherein the first thickness is greater than the second thickness, and wherein the liner is formed atop the bottom surface of the first trench without being formed atop the bottom surface of the second trench.

A method of forming a three-dimensional NAND structure, the method comprising:

• providing a stack of layers comprising a plurality of alternating wordlines and dielectric layers;
• forming a plurality of trenches in the stack of layers, wherein each of the plurality of trenches includes a tiered sidewall and a bottom surface, wherein a first trench of the plurality of trenches is formed to a first depth relative to a top surface of the stack of layers, wherein a second trench of the plurality of trenches is formed to a second depth relative to the top surface of the stack of layers, and wherein the second depth is greater than the first depth;
• and
• forming a liner within each of the plurality of trenches, wherein the liner is deposited at a non-zero angle of inclination relative to a normal extending perpendicular from the top surface of the stack of layers, wherein the liner has a first thickness along the tiered sidewall of the first trench, wherein the liner has a second thickness along the tiered sidewall of the second trench, wherein the first thickness is greater than the second thickness, and wherein the liner is formed atop the bottom surface of the first trench without being formed atop the bottom surface of the second trench.