Memory device and method for repairing a semiconductor memory
View Patent ↗A block repair device is used in a Dynamic Random Access Memory (DRAM) having a primary array with a defective cell and a redundant array with a redundant row. The block repair device stores a block repair configuration that determines the dimensions (e.g., the number of rows and columns spanned) of a repair block. Routing circuitry is configured by the stored block repair configuration to output some row and column address bits from received row and column addresses in a selected ratio. Comparison circuitry compares the row and column address bits output by the routing circuitry with the address of the defective cell that defines the repair block. When a match occurs, the comparison circuitry implements a block repair by activating the redundant row and by causing data to be written to or read from the activated redundant row instead of the primary array.
1. A repairable memory device, comprising:
a primary array with at least one defective cell;
a redundant array with at least one redundant row for storing data addressed to the at least one defective cell of the primary array; and
repair circuitry including a stored location of the at least one defective cell, stored dimensions of a repair block logically spanning the stored location of the at least one defective cell and a comparison circuit to evaluate a received address and to select the at least one redundant row of the redundant array when the received address corresponds with the at least one defective cell of the primary array, the stored dimensions specifying a number of rows and a number of columns of the repair block, the number of rows and the number of columns each being an integer number greater than zero.
2. The repairable memory device of claim 1 , wherein the comparison circuit is configured to compare a portion of the stored location of the at least one defective cell with a portion of the received address, the portions determined by the stored dimension of the repair block.
3. The repairable memory device of claim 1 , wherein the comparison circuit is configured to compare a row address of the stored location of the at least one defective cell with a row address of the received address.
4. A repairable memory device, comprising:
a primary array with at least one defective cell included within a defined repair block;
a redundant array with at least one redundant row for storing data addressed to the at least one defective cell of the primary array; and
repair circuitry configurable to transform addresses of the at least one defective cell within the defined repair block into a linear arrangement for storing within the at least one redundant row of the redundant array when a received address is logically included within the defined repair block, the repair circuitry storing dimensions specifying a number of rows and a number of columns of the defined repair block, the number of rows and the number of columns each being an integer number greater than zero.
5. The repairable memory device of claim 4 , wherein the defined repair block remains within a logical boundary of the primary array.
6. A method for repairing a memory device, comprising:
storing, in a non-volatile manner, dimensions of a repair block encompassing at least one defective memory cell in a primary array for comparison with a received address during a memory read operation; and
storing, in a non-volatile manner, a block repair configuration including at least one redundant row that corresponds to the stored dimensions of the repair block, the stored dimensions specifying a number of rows and a number of columns of the repair block, the number of rows and the number of columns each being an integer number greater than zero.
7. The method of claim 6 , wherein non-volatilely storing the dimensions and the block repair configuration comprise storing using non-volatile elements selected from a group comprising fuses, anti-fuses, and flash EEPROM cells.
8. The method of claim 6 , further comprising, when a comparison match occurs, disabling memory operations within the primary array by disabling a column decoder associated with the primary array.
9. The method of claim 6 , further comprising writing data to or reading data from a cell within the redundant row by writing data to or reading data from a cell selected by a column decoder associated with the redundant row.
10. The method of claim 6 , wherein storing a block repair configuration includes programming a non-volatile element to enable block repair with respect to the redundant row.
11. The method of claim 6 , wherein storing a block repair configuration includes programming a non-volatile element to disable block repair with respect to the redundant row and thereby enable conventional row repair using the redundant row.
12. The method of claim 11 , further comprising storing row and column address bits of a defective cell that define the stored dimensions of the repair block, the storing comprising storing only row address bits of the defective cell.
13. The repairable memory device of claim 1 , wherein the repair circuitry further comprises select circuitry configured to output selection signals to select the number of rows of the repair block based on a block repair configuration.
14. The repairable memory device of claim 13 , wherein the repair circuitry further comprises selection fuses configured to indicate the block repair configuration, the block repair configuration including a repair enable signal and fuse signals corresponding to the stored dimensions.
15. The repairable memory device of claim 14 , wherein the number of selection signals is 2 n , where n is the number of fuse signals.
16. The repairable memory device of claim 13 , wherein the repair circuitry further comprises multiplexer circuitry configured to output compare signals based on the selection signals and row address signals corresponding to the received address.
17. The repairable memory device of claim 16 , wherein, in accordance with the selection signals, the multiplexer circuitry passes certain most significant bits defined by the row address signals.
18. The repairable memory device of claim 15 , wherein the repair circuitry further comprises compare circuitry configured to compare the compare signals against the stored location of the at least one defective cell, the compare circuitry controlling the redundant array to output data signals based on the comparison.
19. The repairable memory device of claim 1 , wherein the repair circuitry further comprises bad address storage fuses capable of storing a portion of an address of the at least one defective cell.
20. The repairable memory device of claim 1 , wherein the primary array is a DRAM array.
21. The repairable memory device of claim 1 , wherein the repairable device is configured to communicate with a separate processor device.