Nonvolatile semiconductor memory device

Abstract

A nonvolatile semiconductor memory device includes first and second word line groups, each including a plurality of stacked word lines above a substrate, a first memory string including a first memory column through the first word line group, a second memory column through the second word line group, and a first memory connection portion electrically coupling the first and second memory columns, and a second memory string including a third memory column through the first word line group, a fourth memory column through the second word line group, and a second memory connection portion electrically coupling the third and fourth memory columns. The first memory connection portion is formed in a first layer of the substrate and the second memory connection portion is formed in a second layer of the substrate that is lower than the first layer.

What is claimed is: 
     
         1 . A nonvolatile semiconductor memory device comprising:
 first and second word line groups, each including a plurality of stacked word lines above a substrate having first and second layers that are insulated from each other;   a first memory string including a first memory column through the first word line group, a second memory column through the second word line group, and a first memory connection portion electrically coupling the first and second memory columns; and   a second memory string including a third memory column through the first word line group, a fourth memory column through the second word line group, and a second memory connection portion electrically coupling the third and fourth memory columns, wherein   the first memory connection portion is formed in the first layer of the substrate and the second memory connection portion is formed in the second layer of the substrate that is lower than the first layer.