Method to dynamically inject errors in a repairable memory on silicon and a method to validate built-in-self-repair logic
An error injection system of a built-in self-repairable memory system renders the redundant spare columns of the repairable memory accessible to built-in self-test (BIST) read and write operations. To this end, the error injection system selectively injects fault data at one or more locations of the main memory during a BIST sequence, causing the BIST controller to issue a repair instruction that allocates one or more spare columns as replacement memory areas for the presumed faulty main memory locations. Thereafter, BIST read/write operations directed to the main memory locations will be performed on the allocated spare columns, thereby allowing the spare columns to be validated as part of the BIST. Injection of fault data to the main memory locations in this manner can also facilitate validation of the built-in self-repair logic by verifying the repair instruction codes that are generated in response to the injected faults.
1. A memory system, comprising:
a built-in self-repairable memory (BISRM) comprising a main memory area and a redundant memory area comprising at least one spare column;
a built-in-self test (BIST) controller configured to validate memory locations of the main memory area by writing test data to the memory locations via a test data bus;
an error injection system configured to inject first fault data and second fault data to a first memory location, of the memory locations, via the test data bus;
wherein the BIST controller is further configured to,
in response to a detection of the first fault data at the first memory location, generate a first repair instruction configured to perform an allocation of a first spare column of the at least one spare column, as a replacement memory area for the memory location; and
in response to a detection of the second fault data at the first memory location and after the allocation of the first spare column, generate a second repair instruction configured to perform an allocation of a second spare column of the at least one spare column, as a replacement memory area for the first memory location; and
a built-in self repairable (BISR) logic verification component configured to generate an error message in response to a determination that the second repair instruction is different than the first repair instruction.
2. The memory system of claim 1 , wherein the allocation of the first spare column causes at least one of a read operation or a write operation directed to the first memory location by the BIST controller to be performed on the first spare column.
3. The memory system of claim 1 , wherein the error injection system comprises at least one error injection component configured to generate the first fault data in accordance with first fault configuration data written to a first fault test data register.
4. The memory system of claim 3 , wherein the first fault configuration data comprises at least first fault address data specifying a first memory address of the BISRM to which the first fault data is to be written.
5. The memory system of claim 4 , wherein the error injection system is configured to switch a test data input of the BISRM from the test data bus to an output of the error injection component in response to determining that a test data address pointer of the BIST controller is equal to the first memory address specified by the first fault address data.
6. The memory system of claim 4 , wherein the first fault configuration data comprises at least bit location data specifying a bit location to which the first fault data is to be written.
7. The memory system of claim 4 , wherein the first fault configuration data comprises at least first fault type data specifying a type of the first fault data.
8. The memory system of claim 7 , wherein the error injection system comprises at least one error injection component configured to generate the second fault data in accordance with second fault configuration data written to a second fault test data register.
9. The memory system of claim 8 , wherein the second fault configuration data comprises at least second fault address data specifying a second memory address of the BISRM to which the second fault data is to be written.
10. The memory system of claim 9 , wherein the first memory address and the second memory address are identical.
11. The memory system of claim 10 , wherein the second fault configuration data comprises at least second fault type data specifying a type of the second fault data.
12. The memory system of claim 11 , wherein the first fault type and the second fault type are identical.
13. The memory system of claim 11 , wherein the first fault type is different from the second fault type.
14. The memory system of claim 3 , further comprising a user interface configured to set the first fault configuration data in accordance with user-defined configuration input.
15. The memory system of claim 1 , wherein the first fault data and the second fault data are identical.