Nonvolatile semiconductor storage device having a shortened time required for a data erasing operation and data erasing method thereof

摘要

It is an object to obtain a nonvolatile semiconductor storage device and a data erasing method thereof in which a time required for a data erasing operation can be shortened. When second and succeeding erasing commands are input at a step SP101, a final voltage value of a batch writing pulse in a last data erasing operation is read from a storage portion (2a) at a step SP102. At a step SP103, next, a control portion (2) sets a starting voltage value of a batch writing pulse in a present data erasing operation based on the final voltage value of the batch writing pulse in the last data erasing operation. For example, in the case in which the final voltage value of the batch writing pulse in the last data erasing operation is VWL=8.00 V and VWell=VSL=-6.00 V, the starting voltage value of the batch writing pulse is currently set to VWL=7.75 V and VWell=VSL=-5.75 V with a reduction of one step.