US 5,969,993 A · Method of restoring data in non-volatile semiconductor memory

Abstract

Disclosed is a method of restoring data in a non-volatile semiconductor memory which has a memory cell array that a plurality of electrically programmable memory cells to be set of several threshold voltages are matrix-disposed, a data erasing means that divides the memory cell array into several blocks and erases in the lump data stored in memory cells included in the divided block, a data writing means that writes data into the memory cells, a data reading means that reads out data from the memory cells, and a control means that controls the operations of the data erasing means, data writing means and data reading means, wherein the non-volatile semiconductor memory has a function that detects the deterioration of data stored in the memory cells and then restores it, the method having the steps of: detecting the data-deterioration state of memory cells included in the block; conducting a light erasing operation with a threshold voltage change smaller than that of an ordinary erasing operation to an erase block including a memory cell with a data-deterioration state that cannot be restored by additional writing; then detecting the data-deterioration state of the memory cells again; and restoring data of a memory cell that a data deterioration is detected.

Claims40

Dependent claims

A method of restoring data in a non-volatile semiconductor memory which comprises a memory cell array that a plurality of electrically programmable memory cells to be set of several threshold voltages are matrix-disposed, a data erasing means that divides said memory cell array into several blocks and erases in the lump data stored in memory cells included in the divided block, a data writing means that writes data into said memory cells, a data reading means that reads out data from said memory cells, and a control means that controls the operations of said data erasing means, data writing means and data reading means, wherein said non-volatile semiconductor memory has a function that detects the deterioration of data stored in the memory cells and then restores it, comprising the steps of:

detecting the data-deterioration state of memory cells included in said block;
conducting a light erasing operation with a threshold voltage change smaller than that of an ordinary erasing operation to an erase block including a memory cell with a data-deterioration state that cannot be restored by additional writing;
then detecting the data-deterioration state of the memory cells again;
and
restoring data of a memory cell that a data deterioration is detected.

2 more elements

A method of restoring data in a non-volatile semiconductor memory which comprises a memory cell array that a plurality of electrically programmable memory cells to be set of several threshold voltages are matrix-disposed, a data erasing means that divides said memory cell array into several first blocks and erases in the lump data stored in memory cells included in the divided first block, a plurality of data writing means that further divide said first block into several second blocks and write data into said memory cells included in said second block, a plurality of data reading means that read out data from said memory cells included in said second block, and a control means that controls the operations of said data erasing means, data writing means and data reading means, wherein said non-volatile semiconductor memory has a function that detects the deterioration of data stored in the memory cells and then restores it, comprising the steps of:

detecting the data-deterioration state of memory cells included in said second block;
conducting a data restoring operation by additional writing to a memory cell with a data-deterioration state that can be restored by additional writing;
conducting said data restoring operation by additional writing for said second block to second blocks included in said first block;
conducting a light erasing operation with a threshold voltage change smaller than that of an ordinary erasing operation to said first block when said first block includes a memory cell with a data-deterioration state that cannot be restored by additional writing;
then detecting the data-deterioration state of the memory cells again;
and
repeating the data restoring operation of a memory cell that a data deterioration is detected.

4 more elements

A method of restoring data in a non-volatile semiconductor memory which comprises a memory cell array that a plurality of electrically programmable memory cells to be set of several threshold voltages are matrix-disposed, a data erasing means that divides said memory cell array into several blocks and erases in the lump data stored in memory cells included in the divided block, a plurality of data writing means that write data into said memory cells included in the divided block, a plurality of data reading means that read out data from said memory cells included in the divided block, and a control means that controls the operations of said data erasing means, data writing means and data reading means, wherein said non-volatile semiconductor memory has a function that detects the deterioration of data stored in the memory cells and then restores it, comprising the steps of:

detecting the data-deterioration state of memory cells included in said block;
conducting a data restoring operation by additional writing to a memory cell with a data-deterioration state that can be restored by additional writing;
conducting a light erasing operation with a threshold voltage change smaller than that of an ordinary erasing operation to said block when said block includes a memory cell with a data-deterioration state that cannot be restored by additional writing;
then detecting the data-deterioration state of the memory cells again;
and
repeating the data restoring operation of a memory cell that a data deterioration is detected.

3 more elements

Dependencies are inferred from the claim text.

Method of restoring data in non-volatile semiconductor memory

Life of this patent

Method of restoring data in non-volatile semiconductor memory

Life of this patent

Abstract

Claims40