3d memory program disturbance improvement

Abstract

A memory device has a plurality of blocks of memory cells and a plurality of bit lines, each block including a group of word lines, and a set of NAND strings. Each block in the plurality of blocks of memory cells has a plurality of sub-blocks, each sub-block including a distinct subset of the set of NAND strings of the block selected, and a respective sub-block string select line. Control circuits are configured to execute a program operation including applying word line voltages and string select line voltages at a precharge level to precharge the set of NAND strings in the selected block, then lowering the gate voltages on all the sub-block string select lines of the block, and then lowering the word line voltages on the group of word lines. Thereafter, the program of cells in a selected sub-block is executed.