Reducing memory failures in integrated circuits
View Patent ↗Memory reliability is improved by using redundancy to repair errors detected by ECC. In one embodiment, redundancy repairs errors which cannot be corrected by ECC. The redundancy can employ the use of electronic fuses, enabling repairs after an IC containing the memory is packaged. Redundancy can also be performed prior to packaging of the IC.
1. A method of reducing memory failures in an individual integrated circuit (IC) having an array of memory cells comprising:
testing the array using error correction code (FCC) prior to packaging;
repairing defects detected during testing which are not correctable by ECC;
performing a read operation to a memory address for a memory location in the array after packaging;
retrieving a data word of information from the memory location in the array corresponding to the memory address;
determining whether the data word contains an error using ECC;
when the error is not correctable by ECC, determining availability of a redundancy unit within the IC for repairing a defective memory element corresponding to the error, wherein the redundancy unit includes a fuse block and a corresponding redundant memory element; and
if a redundancy unit is available, programming the fuse block of the redundancy unit with the memory address of the error to cause the redundant memory element corresponding to the fuse block to replace the defective memory element.
2. The method according to claim 1 wherein the array comprises ferroelectric memory cells.
3. The method according to claim 1 wherein the array comprises memory cells arranged in a folded bitline, open bitline, open-folded bitline, or series architecture.
4. The method according to claim 3 wherein the array comprises ferroelectric memory cells.
5. The method according to claim 1 wherein the repairing comprises using a redundancy block including at least one redundancy unit.
6. The method according to claim 5 wherein the fuse block comprises electronic fuses, the electronic fuses comprising ferroelectric memory cells.
7. The method according to claim 1 wherein the fuse block comprises a hybrid fuse block having a first subfuse block comprising electronic fuses and a second subfuse block comprising laser-blowable fuses.
8. The method according to claim 7 wherein the electronic fuses comprises ferroelectric memory cells.
9. The method according to claim 1 wherein the repairing comprises using a redundancy block including at least one redundancy unit, wherein the fuse block comprises electronic or laser-blowable fuses for programming a memory address associated with the error.
10. The method according to claim 9 wherein the electronic fuses comprise ferroelectric memory cells.
11. The method according to claim 9 wherein the fuse block comprises a hybrid fuse block having a first subfuse block comprising electronic fuses and a second subfuse block comprising laser-blowable fuses.
12. The method according to claim 11 wherein the electronic fuses comprise ferroelectric memory cells.
13. A method of reducing memory failures in an integrated circuit (IC) having an array of memory cells comprising:
providing the IC wherein the array has been tested using error correction code (ECC) prior to packaging;
reading data from an address in the array;
testing data read from the address using ECC;
if the data contains a non-correctable error using ECC, repairing the memory cells corresponding to the error using redundancy for repairing after packaging if redundancy is available.
14. The method of claim 13 wherein the repairing comprises using a redundancy block including at least one redundancy unit, the redundancy unit includes a redundant memory element associated with a fuse block, the fuse block comprising electronic fuses for programming an address associated with the error.
15. The method according to claim 14 wherein the electronic fuses comprise ferroelectric memory cells.
16. The method according to claim 14 wherein the fuse block comprises a hybrid fuse block having a first subfuse block comprising electronic fuses and a second subfuse block comprising laser-blowable fuses.
17. The method according to claim 16 wherein the electronic fuses comprise ferroelectric memory cells.
18. An integrated circuit (IC) comprising:
an array of memory cells, the array of memory cells having been tested using error correction code ECC) prior to packaging; and
redundancy for repairing errors after packaging, wherein the errors are not correctable using ECC.
19. The IC of claim 18 further comprising a redundancy block including at least one redundancy unit, the redundancy unit includes a redundant memory element associated with a fuse block, the fuse block comprising electronic fuses for programming an address associated with the error.
20. The IC of claim 19 wherein the electronic fuses comprise ferroelectric memory cells.
21. The IC of claim 19 wherein the fuse block comprises a hybrid fuse block having a first subfuse block comprising electronic fuses and a second subfuse block comprising laser-blowable fuses.
22. The IC of claim 21 wherein the electronic fuses comprise ferroelectric memory cells.