US Patent 10978155 3D NAND memory Z-decoder

Apparatus and methods are disclosed, including an apparatus having first and second units of vertically arranged strings of memory cells, each unit including multiple tiers of a semiconductor material, including multiple tiers of memory cells, each tier of memory cells including an access line of at least one memory cell. The access line of a first tier of the first unit can be selectively coupled to a first drive transistor through a first decoder transistor, the access line of a first tier of the second unit can be selectively coupled to the first drive transistor through a second decoder transistor, and the access line of the first tier of the first unit can be selectively coupled to the access line of the first tier of the second unit through the first and second decoder transistors.