US Patent 7495955 Nonvolative semiconductor memory device and operating method thereof

A nonvolatile semiconductor memory device includes a plurality of nonvolatile memory cells for a user area and a trimming data storage area; and a plurality of word lines. A first trimming data is stored in the trimming data storage area, and is for adjusting a read voltage to be applied to a selected word line as one of the plurality of word lines in a read operation. The read voltage is set to a voltage which exceeds a maximum voltage in an adjustable voltage range based on the first trimming data when the read operation is carried out to the trimming data storage area.