Semiconductor memory device and method of operating the same
AssigneeNEC Electronics Corporation
InventorKenichirou Tominaga
Life of this patent
Estimating the term…
Abstract
A semiconductor memory device has: a first memory including a data storage area and a redundant data storage area; a second memory as a nonvolatile memory storing a defect address of the first memory; a register; a sequencer; and a decoder. The sequencer reads out the defect address from the second memory and stores the read defect address in the register. When accessing a target address in the first memory, the decoder compares the target address with the defect address stored in the register, and selects any of the data storage area and the redundant data storage area of the first memory based on a result of the comparison.
Claims20
A semiconductor memory device comprising:
- a first memory including a data storage area and a redundant data storage area;
- a second memory as a nonvolatile memory storing a defect address of said first memory;
- a register configured to store said defect address;
- a sequencer configured to read out said defect address from said second memory and store said read defect address in said register;
- and
- a decoder configured to, when accessing a target address in said first memory, compare said target address with said defect address stored in said register and select any of said data storage area and said redundant data storage area of said first memory based on a result of said comparison.
A method of operating a semiconductor memory device,
- said semiconductor memory device having:
- a first memory including a data storage area and a redundant data storage area;
- a second memory as a nonvolatile memory storing a defect address of said first memory;
- and a register,
- said method comprising:
- (A) reading out said defect address from said second memory and storing said read defect address in said register;
- (B) when accessing a target address in said first memory, comparing said target address with said defect address stored in said register;
- and
- (C) selecting any of said data storage area and said redundant data storage area of said first memory based on a result of said comparison in said (B) step.
A semiconductor memory device comprising:
- a first nonvolatile memory having a plurality of data storage areas and at least one redundant data storage area;
- a second nonvolatile memory storing replacement addresses out of a plurality of addresses corresponding to respective of said plurality of data storage areas in said first nonvolatile memory;
- a register group;
- and
- a sequencer configured to read out all said replacement addresses from said second nonvolatile memory and store said all replacement addresses in said register group in response to an operation command,
- wherein said all replacement addresses are related to respective addresses of said at least one redundant data storage area, and
- said first nonvolatile memory is accessed based on a result of comparison between a target address in said first nonvolatile memory and said all replacement addresses stored in said register group.
Dependencies are inferred from the claim text.