As illustrated in FIG. 2B, the shape of the memory hole MH in an XY plane is substantially circular. In other words, the cross section in the direction substantially perpendicular to the stacking direction of the columnar body CL1 is substantially circular. A block insulating film 12a configuring a portion of the charge trapping film 103 may be provided between the first insulating film 11 and the first conductive film 12. The block insulating film 12a is, for example, a silicon oxide film or a metal oxide film. The metal oxide film may be made of, for example, aluminum oxide. A barrier film 12bb may be provided between the first insulating film 11 and the first conductive film 12 and between the first conductive film 12 and the charge trapping film 103. When the first conductive film 12 is made of tungsten, the barrier film 12bb may be, for example, a stacked structure film of titanium nitride (TiN) and titanium (Ti). The block insulating film 12a prevents back tunneling of charges from the first conductive film 12 to the charge trapping film 103 side. The barrier film 12bb improves the adhesion between the first conductive film 12 and the block insulating film 12a.
The shape of the semiconductor portion 102 may be, for example, a cylindrical shape having a bottom. The semiconductor portion 102 contains, for example, silicon. The silicon may be, for example, polysilicon obtained by crystallizing amorphous silicon. The semiconductor portion 102 is made of, for example, undoped silicon. The semiconductor portion 102 may be p-type silicon. The semiconductor portion 102 functions as a channel region of the memory cell MC and the source-side select gate SGS.
