Patent ID: 8441862
Filing Date: 2013-05-14
Classification: G11C

Abstract:
1. A program method for a multi-bit memory device comprising: a first step of programming a first group of memory cells of the multi-bit memory device to a first state of a first group of states according to a first verify voltage level of a first group of verify voltage levels, and programming a second group of memory cells of the multi-bit memory device to a second state of the first group of states according to a second verify voltage level of the first group of verify voltage levels; and a second step of programming each memory cell of the first group of memory cells to a state within a second group of states according to a verify voltage level of a second group of verify voltage levels within a first range of levels, and programming each memory cell of the second group of memory cells to a state within a third group of states according to a verify voltage level of a third group of verify voltage levels within a second range of levels, wherein the lowest verify voltage level in the second range of levels is higher than the highest verify voltage level in the first range of levels, and wherein a first voltage difference between adjacent verify voltage levels within the first range of levels is different from a second voltage difference between the highest verify voltage level of the second group of verify voltage levels and the lowest verify voltage level of the third group of verify voltage levels.