Program disturb is reduced in non-volatile storage by preventing source
side boosting in selected NAND strings. A self-boosting mode which
includes an isolation word line is used. A channel area of an inhibited
NAND string is boosted on a source side of the isolation word line before
the channel is boosted on a drain side of the isolation word line.
Further, storage elements near the isolation word line are kept in a
conducting state during the source side boosting so that the source side
channel is connected to the drain side channel. In this way, in selected
NAND strings, source side boosting can not occur and thus program disturb
due to source side boosting can be prevented. After the source side
boosting, the source side channel is isolated from the drain side
channel, and drain side boosting is performed.