Writing method, reading method and memory device for hiding data

Abstract

A writing method and a reading method for hiding data in a memory device and a memory device thereof are provided. The memory device may be a 3D NAND flash with high capacity and high performance. The writing method includes: providing a memory block, each memory cell including an erase state and potential states, each potential state including a first and a second sub-potential states; performing a first program operation to move threshold voltages of a first portion in a specific page to the first sub-potential state; performing a second program operation to move threshold voltages of a second portion in the specific page to the second sub-potential state. The first program operation includes: applying a first pass voltage to a first word line of a first page, the first page is adjacent a side of the specific page; and, applying a second pass voltage to a second word line of a second page, the second page is adjacent another side of the specific page.