Dummy vertical structures for etching in 3d nand memory and other circuits

A method for manufacturing a memory device, comprising:

• forming an array of holes through a stack of patterned conductor layers separated by insulating layers;
• forming an array of vertical pillars extending through the stack of patterned conductor layers in the holes in the array of holes;
• etching a first set of slits and a second set of slits through the stack of patterned conductor layers using a single mask, the first set of slits disposed across the holes in respective rows of holes, the second set of slits including slits connecting adjacent slits in the first set of slits at ends, thereby forming conductive strips including strips continuous with a pad and other strips isolated from the pad, wherein memory cells are disposed at cross-points between the vertical pillars and patterned conductor layers, the array of vertical pillars having an array boundary proximal to the pad;
• forming a first set of isolation blocks in the first set of slits through the plurality of patterned conductor layers separating the strips continuous with the pad from the other strips isolated from the pad;
• and
• forming a second set of isolation blocks in the second set of slits inside the array boundary and extending through the plurality of patterned conductor layers isolating the other strips from the pad.

A 3D circuit, comprising:

• a stack of patterned conductor layers, at least a plurality of the layers comprising conductive strips including strips continuous with a pad and other strips isolated from the pad;
• an array of circuit structures in the stack of patterned conductor layers, the array having an array boundary proximal to the pad;
• a first set of isolation blocks extending through the plurality of patterned conductor layers separating the strips continuous with the pad from the other strips isolated from the pad;
• and
• a second set of isolation blocks inside the array boundary and extending through the plurality of patterned conductor layers isolating the other strips from the pad.