Patent ID: 8916921

Claim:
A non-volatile semiconductor storage device comprising: a plurality of memory strings each having a plurality of electrically rewritable memory cells connected in series, each of the memory strings comprising: a first semiconductor layer having a columnar portion extending in a vertical direction with respect to a substrate; an electric charge accumulation layer surrounding a side surface of the first semiconductor layer; and a plurality of first conductive layers surrounding a side surface of the electric charge accumulation layer and functioning as control electrodes of the memory cells, the plurality of first conductive layers being provided at a certain interval L in the vertical direction, with a dielectric sandwiched therebetween, the dielectric including a first dielectric with a lower dielectric constant than that of silicon oxide, the certain interval L being set so that the first dielectric has an equivalent oxide thickness D EOT that satisfies the following relation (1), wherein the equivalent oxide thickness D EOT is defined as EOT=T×(∈ ox /∈ x ), in which T is a physical thickness of the first dielectric, ∈ ox is the dielectric constant of silicon oxide, and ∈ x is the dielectric constant of the first dielectric: D sio2 <D EOT <D k (1) in which D sio2 denotes an equivalent oxide thickness of the first dielectric with a minimum thickness that can withstand a maximum voltage to be applied to the first conductive layers, and, R sio2 defines a resistance value of an entire part of the first semiconductor layer that is adjacent in a direction parallel to the substrate to one of the first conductive layers, and that has an extent between top and bottom surfaces of the one of the first conductive layers, if the first dielectric was composed of silicon oxide having a film thickness of D sio2 , and D k denotes an equivalent oxide thickness of the first dielectric when the first dielectric provides the resistance value R sio2 in the part of the first semiconductor layer.