Forced-bias method in sub-block erase

A method is provided for operating a NAND array that includes a plurality of blocks of memory cells. A block of memory cells includes a plurality of NAND strings having channel lines between first string select switches and second string select switches. The plurality of NAND strings shares a set of word lines between the first and second string select switches. A channel-side erase voltage is applied to the channel lines through the first string select switches in a selected block. Word line-side erase voltages are applied to a selected subset of the set of word lines in the selected block to induce tunneling in memory cells coupled to the selected subset. Word line-side inhibit voltages are applied to an unselected subset of the set of word lines in the selected block to inhibit tunneling in memory cells coupled to the unselected subset.