US Patent 11676665 Memory device and erasing and verification method thereof

A memory device includes a memory string and a control circuit coupled to the memory string. The memory string includes a top select gate, word lines, a bottom select gate, and a P-well. The control circuit is configured to, in an erasing operation, apply an erasing voltage to the P-well, apply a verifying voltage to a selected word line of the word lines after applying the erasing voltage to the P-well, and apply a first turn-on voltage to the bottom select gate, starting after applying the erasing voltage to the P-well and before applying the verifying voltage to the selected word line.