Self-Repair Memory Using Reuse Table for Post-Production Bitcell Failures
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Solution Overview
Problem
Conventional memory built-in self-testing (MBIST) logic is inadequate as it only provides initial testing and repair before operational use, ignoring unused bits and failing to extend the useful life of memory devices post-production due to end-of-life bitcell failures.
Innovation Solution
Implementing a self-repair memory technique that uses a reuse table to self-heal or self-repair memory during idle cycles after manufacturing and operational use, reusing data stored in the table to extend the device's lifespan by performing additional post-production testing and repairs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional MBIST logic is used for initial testing and repair before operational use, then pre-production errors can be repaired, but the memory device cannot extend its useful life post-production due to end-of-life bitcell failures
Solution Approach 1:
The memory device performs self-diagnosis and self-repair operations using built-in test logic that operates during idle cycles. The system automatically detects bitcell failures and redirects failed addresses to spare locations without external intervention, enabling continuous self-maintenance throughout the device's operational life.
Solution Approach 2:
The system performs preliminary repair actions by establishing a mapping between failed addresses and spare locations during initial testing. This pre-configured mapping allows rapid redirection of failed bitcells to functional spares when failures occur during operation, minimizing downtime and extending device life.
2Productivity
If conventional MBIST methodologies are used to test memories, then initial testing can be performed, but many unused bits are never used over the life of the memory and are simply ignored
Solution Approach 1:
The test logic is designed to serve multiple functions: initial production testing, ongoing operational monitoring, and continuous repair operations. The same built-in test apparatus that performs initial MBIST also monitors for failures and executes repair operations throughout the device's life, maximizing utilization of available resources.
Solution Approach 2:
The testing and repair process continues continuously throughout the device's operational life rather than being limited to initial production testing. The system repeatedly performs diagnosis and repair operations during idle cycles, ensuring ongoing functionality and extending the memory's useful life well beyond initial manufacturing.
3Ease of manufacture
If conventional MBIST logic only provides initial testing before operational use, then pre-production errors can be identified, but post-production failures cannot be addressed
Solution Approach 1:
The testing and repair system transitions from a static initial-test-only approach to a dynamic continuous operation. The built-in test logic remains active throughout the device's life, adapting to detect and repair failures as they occur in production and post-production environments, making the system responsive to real-time conditions.
Data Source
AI summary
Various implementations described herein are directed to a method that tests and repairs memory fabricated on a wafer or a package. The method may generate and store a reuse table based on memory repair results. The method may manufacture the memory after repairing the memory. The method may access and reuse data stored in the reuse table to repair the memory after manufacturing the memory.