OTP Memory Repair Using Backup Zones and Address Remapping
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Solution Overview
Problem
As memory cells in one-time programmable (OTP) memories become smaller, the number of defective cells increases, making existing error correction methods insufficient, and implementing them reduces memory robustness, necessitating a more effective repair method.
Innovation Solution
A method for repairing OTP memories by writing digital data to alternative memory locations and storing the original location's address in a separate zone, using address and data repair zones to facilitate recovery, ensuring the same failure probability and robustness as normal operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cells are reduced in size to increase storage density, then storage capacity is improved, but the number of defective memory cells increases
Solution Approach 1:
The memory space is segmented into three distinct zones: a first memory zone for primary data storage, a second memory zone for backup data storage, and a third memory zone for storing address information and identifiers. This segmentation allows defective cells in the first zone to be repaired by redirecting access to corresponding locations in the second zone, thereby maintaining reliability while preserving high storage capacity achieved through cell size reduction
Solution Approach 2:
The invention changes the operational parameters of the memory system by introducing a repair mechanism that modifies access patterns rather than physical cell dimensions. When a defective cell is detected in the first memory zone, the system changes the access parameter to read from the corresponding location in the second memory zone instead, allowing the same physical cell to serve dual purposes under different operational conditions
2Reliability
If error correction methods are implemented to compensate for defective cells, then reliability is improved, but memory robustness is reduced
Solution Approach 1:
The repair mechanism is pre-configured during memory manufacturing or initialization, with the second and third memory zones prepared in advance to receive and store backup data and address information. This preliminary action ensures that when defects are detected during operation, the repair process can immediately redirect access without compromising the structural integrity or robustness of the original memory architecture
Solution Approach 2:
The third memory zone acts as an intermediary by storing address information and identifiers that map between the first and second memory zones. This intermediary layer enables the system to maintain the original memory structure and access patterns while transparently redirecting defective cell access to functional cells, thereby preserving memory robustness while achieving error correction
3Reliability
If error correction methods are implemented to operate memory upon test, then defective cells are compensated, but manufacturing yield is reduced
Solution Approach 1:
By segmenting memory into distinct zones with dedicated repair functionality, the invention allows defective cells to be repaired without requiring complete memory array redundancy. The second and third memory zones serve as repair resources that can handle defective cells from the first zone, enabling higher manufacturing yield compared to traditional error correction methods that would require larger overall memory structures
Solution Approach 2:
The invention creates copies of data and address information in the second and third memory zones that can be used to replace defective cells in the first zone. This copying mechanism allows the memory to maintain full operational capability despite manufacturing defects, improving yield by enabling sale of previously defective memory devices
Data Source
AI summary
A one-time programmable memory includes memory locations that are each identified by an address, where each memory location is configured to store a digital data having a given number of bits. The memory locations are arranged into a first memory zone, a second memory zone, and a third memory zone. A method for controlling the one-time programmable memory includes: determining that a read operation of a digital data in a first memory location of the first memory zone has failed, and in response thereto writing the digital data in a second memory location of the second memory zone and writing, in a third memory location of the third memory zone, the address of the first memory location and an identifier of the second memory location.