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 method for substituting a redundant memory cell in a semiconductor memory, comprising:
detecting a defective memory cell in a primary array;
selecting a repair block encompassing the defective memory cell in the primary array;
non-volatilely storing dimensions of the repair block within the semiconductor memory for comparison with a received address during a memory read operation; and
non-volatilely storing a block repair configuration including a redundant row that corresponds to the stored dimensions of the repair block within the semiconductor memory.
2. The method of claim 1 wherein both storing acts comprise storing using non-volatile elements selected from a group comprising fuses, anti-fuses, and flash EEPROM cells.
3. The method of claim 1 further comprising routing received row and column address bits comprises muxing received row and column address bits in accordance with the block repair configuration.
4. The method of claim 1 , further comprising, when a match occurs, disabling memory operations within the primary array by disabling a column decoder associated with the primary array.
5. The method of claim 1 , further comprising writing data to or reading data from a cell within the redundant row comprises writing data to or reading data from a cell selected by a column decoder associated with the redundant row.
6. The method of claim 1 wherein storing a block repair configuration includes programming a non-volatile element to enable block repair with respect to the redundant row.
7. The method of claim 1 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.
8. The method of claim 7 , further comprising storing row and column address bits of a defective cell that define the stored dimensions of the repair block, said storing comprising storing only row address bits of the defective cell.
9. A method for repairing a semiconductor memory, comprising:
selecting a repair block within a primary array that encompasses a defective cell;
storing row and column address bits of the defective cell that define the repair block;
storing a block repair configuration that corresponds to the repair block;
routing received row and column address bits for determining when a received address falls within the repair block;
disabling the defective cell within the primary array when a match occurs; and
firing a cell within a redundant row selected in accordance with the stored row and column address bits of the defective cell.
10. The method of claim 9 , wherein the storing acts comprise storing in non-volatile elements selected from a group comprising fuses, anti-fuses, and flash EEPROM cells.
11. The method of claim 9 , wherein routing received row and column address bits comprises muxing received row and column address bits in accordance with the block repair configuration.
12. The method of claim 9 , further comprising, when a match occurs, disabling memory operations within the primary array by disabling a column decoder associated with the primary array.
13. The method of claim 9 , wherein firing a cell within the redundant row comprises writing data to or reading data from the cell selected by a column decoder associated with the redundant array.
14. The method of claim 9 , wherein storing a block repair configuration includes programming a non-volatile element to enable block repair with respect to the redundant row.
15. The method of claim 9 , 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.
16. The method of claim 15 , wherein storing row and column address bits of the defective cell that define the repair block comprises storing only row address bits of the defective cell.