Apparatus for dynamically repairing a semiconductor memory

• US 7,212,456 B2
• Filed: 08/16/2005
• Issued: 05/01/2007
• Est. Priority Date: 07/18/2002
• Status: Expired due to Fees

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Callaway, Brian P., Baum, Aaron M.
• Primary Examiner(s): Nguyen; Tuan T.
• Application Number:
  US11/205,634
• Publication Number:
  US 20060036921A1
• Time in Patent Office: 623 Days
• Field of Search: 365/201, 365/200, 365/189.07
• US Class Current: 365/201
• CPC Class Codes: G11C 2029/2602 Concurrent test
• CPC Class Codes: G11C 2029/3602 Pattern generator
• CPC Class Codes: G11C 2029/4002 Comparison of products, i.e. test results of chips or with golden chip
• CPC Class Codes: G11C 29/006 at wafer scale level, i.e. wafer scale integration [WSI]
• CPC Class Codes: G11C 29/26 Accessing multiple arrays G11C29/24 takes precedence
• CPC Class Codes: G11C 29/28 Dependent multiple arrays, e.g. multi-bit arrays
• CPC Class Codes: G11C 29/38 Response verification devices
• CPC Class Codes: G11C 29/44 Indication or identification of errors, e.g. for repair
• CPC Class Codes: G11C 29/4401 for self repair
• CPC Class Codes: G11C 29/72 with optimized replacement algorithms
• CPC Class Codes: G11C 29/76 using address translation or modifications
• CPC Class Codes: G11C 29/785 with redundancy programming schemes

Abstract

An architecture for dynamically repairing a semiconductor memory, such as a Dynamic Random Access Memory (DRAM), includes circuitry for dynamically storing memory element remapping information. Memory is tested for errors by writing, then reading a plurality of memory blocks, such as rows or columns, in parallel. Memory is dynamically reprogrammed in order to remap unused spare memory elements for failed memory elements when errors are detected. Unused spare memory elements are remapped utilizing a circuit that overrides unblown fuses or antifuses.

Claims

1. A semiconductor memory including a capability for testing for memory faults, comprising:

a first memory block comprising a first plurality of bits of memory;

a second memory block comprising a second plurality of bits of memory; and

a circuit configured for;

writing a pattern of bits to the first memory block and the second memory block;

reading a first plurality of read bits from the first memory block;

reading a second plurality of read bits from the second memory block; and

comparing each one of the first plurality of read bits with a corresponding one of the second plurality of read bits.

2. The semiconductor memory of claim 1, wherein the circuit is further configured for determining that a fault has occurred in the second memory block when one of the second plurality of read bits differs from a corresponding one of the first plurality of read bits.

3. The semiconductor memory of claim 1, further comprising a third memory block comprising a third plurality of bits of memory and wherein the circuit is further configured for:

writing the pattern of bits to the third memory block;

reading a third plurality of read bits from the third memory block; and

comparing each one of the second plurality of read bits with a corresponding one of the third plurality of read bits.

4. The semiconductor memory of claim 3, wherein the circuit is further configured for comparing each one of the first plurality of read bits with a corresponding one of the third plurality of read bits.

5. The semiconductor memory of claim 3, wherein the circuit is further configured for determining that a fault has occurred in the second memory block when one of the second plurality of read bits differs from a corresponding one of the first plurality of read bits and differs from a corresponding one of the third plurality of read bits.

6. The semiconductor memory of claim 3, further comprising a fourth memory block comprising a fourth plurality of bits of memory and wherein the circuit is further configured for:

writing the pattern of bits to the fourth memory block;

reading a fourth plurality of read bits from the fourth memory block; and

comparing each one of the third plurality of read bits with a corresponding one of the fourth plurality of read bits.

7. The semiconductor memory of claim 6, wherein the circuit is further configured for comparing each one of the first plurality of read bits with a corresponding one of the fourth plurality of read bits.

8. The semiconductor memory of claim 6, wherein the circuit is further configured for comparing each one of the second plurality of read bits with a corresponding one of the fourth plurality of read bits.

9. The semiconductor memory of claim 6, wherein the circuit is further configured for determining that a fault has occurred in the second memory block when one of the second plurality of read bits differs from a corresponding one of the first plurality of read bits, differs from a corresponding one of the third plurality of read bits, and differs from a corresponding one of the third plurality of read bits.

10. The semiconductor memory of claim 1, further comprising a built-in self-test (BIST) circuit for generating the pattern of bits.

11. The semiconductor memory of claim 1, further comprising at least one additional memory block comprising an additional plurality of memory bits and wherein the circuit is further configured for:

writing the pattern of bits to each of the at least one additional memory block; and

repeating for each of the at least one additional memory block, the acts of;

reading an additional plurality of read bits from the at least one additional memory block;

comparing each bit in the first plurality of read bits with a corresponding bit in the additional plurality of read bits; and

comparing each bit in the second plurality of read bits with a corresponding bit in the additional plurality of read bits.

12. The semiconductor memory of claim 11, wherein the circuit is further configured for determining that a fault has occurred in a faulty memory block selected from the group consisting of the first memory block, the second memory block, and each of the at least one additional memory block when a bit in the plurality of read bits from the faulty memory block differs from a corresponding bit in the plurality of read bits from all of the other elements of the group.

13. A semiconductor memory including a capability for testing for memory faults, comprising:

a first collection of memory bits;

a second collection of memory bits; and

a circuit configured for;

writing a string of bits to the first collection of memory bits and the second collection of memory bit;

reading a first string of read bits from the first collection of memory bits;

reading a second string of read bits from the second collection of memory bits; and

comparing each bit in the first string of read bits with a corresponding bit in the second string of read bits.

14. The semiconductor memory of claim 13, wherein the circuit is further configured for determining that a fault has occurred in the first collection of memory bits or in the second collection of memory bits when a bit in the first string of read bits differs from a corresponding bit in the second string of read bits.

15. The semiconductor memory of claim 13, further comprising at least one additional collection of memory bits and wherein the circuit is further configured for:

writing the string of bits to each of the at least one additional collection of memory bits; and

repeating for each of the at least one additional collection of memory bits, the acts of;

reading an additional string of read bits from the at least one additional plurality of memory bits;

comparing each bit in the first string of read bits with a corresponding bit of the additional string of read bits; and

comparing each bit in the second string of read bits with a corresponding bit of the additional string of read bits.

16. The semiconductor memory of claim 15, wherein the circuit is further configured for determining that a fault has occurred in a faulty collection of memory bits selected from the group consisting of the first collection of memory bits, the second collection of memory bits, and each of the at least one additional collection of memory bits when a bit in the string of read bits from the faulty collection of memory bits differs from a corresponding bit in the string of read bits from all of the other elements of the group.

17. The semiconductor memory of claim 13, further comprising a built-in self-test (BIST) circuit for generating the string of bits.