Flash memory device having efficient refresh operation

1. A flash memory device comprising:

a normal memory array including a plurality of normal memory cells arranged in a matrix of word lines and bit lines, wherein the plurality of normal memory cells are divided into a plurality of memory blocks and are programmable and erasable;

a refresh address generation unit configured to generate a refresh block address, wherein the refresh block address is sequentially increased in response to activation of an refresh driving signal; and

a refresh driving unit that is driven to refresh a memory block specified by the refresh block address among the memory blocks of the normal memory array in a unit refresh frame, and generate the refresh driving signal,

wherein the refresh driving signal is activated in the unit refresh frame, and deactivated when the memory block specified by the refresh block address is determined as refresh failure.

2. The flash memory device of claim 1 , wherein refresh block address is retained when power is not supplied as well as when power is supplied.

3. The flash memory device of claim 1 , wherein the refresh address generation unit comprises:

a refresh address storing memory including a plurality of refresh memory cells which are configured to store refresh block data;

a refresh address controller that is driven to increase the refresh block data in response to activation of the refresh driving signal; and

a refresh address generator configured to generate the refresh block address corresponding to the refresh block data.

4. The flash memory device of claim 3 , wherein the plurality of normal memory cells of the normal memory array and the plurality of refresh memory cells of the refresh address storing memory are non-volatile memory cells.

5. The flash memory device of claim 3 , wherein the plurality of refresh memory cells are capable of retaining the stored refresh block data when power is not supplied as well as when power is supplied.

6. The flash memory device of claim 1 , wherein the refresh driving unit comprises:

a row selection unit that is driven to activate word lines of the memory block specified by the refresh block address in the unit refresh frame;

a column selection sensing unit that is driven to specify a bit line according to a column address, sense data of the specified bit line, and output the sensed data as sensing data;

a curing cell determination unit configured to generate a disturbance determination signal, and to be activated when the memory block specified by the refresh block address is determined as refresh failure; and

a controller configured to generate the refresh driving signal, wherein the refresh driving signal is activated when the unit refresh frame occurs and deactivated when the disturbance determination signal is activated.

7. The flash memory device of claim 6 , wherein the row selection unit comprises:

a block address selector configured to generate a selected block address which is either the refresh block address or a normal block address selected based on whether a refresh command occurs, wherein the normal block address specifies a memory block of the normal memory array in a normal operation mode; and

a row decoder that is driven to specify the word lines of the normal memory array by decoding the selected block address and a low row address.

8. The flash memory device of claim 6 , wherein the column selection sensing unit comprises:

a column decoder configured to activate a specific column selection signal by decoding the column address; and

a column selection sense amplifier configured to sense data of a bit line selected according to the specific column selection signal activated by the column decoder, and provide the sensed data as the sensing data.

9. The flash memory device of claim 6 , wherein the curing cell determination unit comprises:

a data checking unit configured to check a data value of the sensing data based on a first reference voltage or a second reference voltage;

a first register configured to store the data value of the sensing data checked based on the first reference voltage as first checking read data;

a second register configured to store the data value of the sensing data checked based on the second reference voltage as second checking read data; and

a data comparator configured to compare the first checking read data and the second checking read data to generate the disturbance determination signal, wherein the disturbance determination signal is activated when first checking read data and second checking read data of a normal memory cell of a memory block designated in the unit refresh frame are different.

10. The flash memory device of claim 9 , wherein the memory block is determined as refresh failure when the first checking read data and the second checking read data of at least one among the normal memory cells are different.

11. The flash memory device of claim 9 , wherein the data checking unit is configured to check the data value of the sending data based on the first reference voltage in response to activation of a first checking driving signal provided from the controller.

12. The flash memory device of claim 9 , wherein the data checking unit is configured to check the data value of the sending data based on the second reference voltage in response to activation of a second checking driving signal provided from the controller.

13. The flash memory device of claim 9 , wherein the second reference voltage is higher than the first reference voltage.