Patent ID: 7224615
Filing Date: 2007-05-29
Classification: G11C

Abstract:
1. A data write method for a non-volatile semiconductor memory device which comprises memory cells for at least a page, first data storage sections and second data storage sections, each of the number of the first data storage sections and the second storage sections corresponding to the number of the memory cells, the method comprising: receiving data to be written in the memory cells; storing the data in the first data storage sections; copying the data from the first data storage sections to the second data storage sections; selecting an initial value for write voltage; setting write control voltage to one of a first voltage, a second voltage which is higher than the first voltage, and a third voltage which is higher than the second voltage, the write control voltage being set to the first voltage when both of the data corresponding to the memory cells in the first data storage sections and the data corresponding to the memory cells in the second data storage sections are “0”, the write control voltage being set to the second voltage when the data corresponding to the memory cells in the first data storage sections are “0” and the data corresponding to the memory cells in the second data storage sections are “1”, the write control voltage being set to the third voltage when the data corresponding to the memory cells in the first data storage sections are “1”; writing the data in the memory cells using the write voltage and the write control voltage; checking whether or not all the data in the second data storage sections are “1 or more”; determining that a status of a first step is satisfactory when all the data in the second data storage sections are “1 or more”, and that the status of the first step is not satisfactory when not all the data in the second data storage sections are “1 or more”; starting a first step write verify operation if the status of the first step is not satisfactory, so that the data having a value of “0” in the second data storage sections, which correspond to the memory cells whose verification result is satisfactory, are changed to “1”, and the data having a value of “1 or more” in the second data storage sections, which correspond to the memory cells whose verification result is satisfactory, are increased by 1; starting a second step write verify operation if the status of the first step is satisfactory or when the first step write verify operation is finished, so that the data having a value of “0” in the first data storage sections, which correspond to the memory cells whose verification result is satisfactory, are changed to “1”; checking, after the second step write verify operation, whether or not all the data in the first data storage sections are “1”; determining that a status of a second step is satisfactory when all the data in the first data storage sections are “1”, and that the status of the second step is not satisfactory when not all the data in the first data storage sections are “1”; completing write operation if the status of the second step is satisfactory; and setting the write control voltage to fourth voltage if the status of the second step is not satisfactory, for writing the data in the memory cells using the write voltage and the write control voltage, the fourth voltage being higher than the second voltage and lower than the third voltage.