Chip Tester Redundancy Reallocation for Defective Guarantee Blocks
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Solution Overview
Problem
The increasing demand for reliable semiconductor memory devices is hindered by the issue of defective blocks in both normal and guarantee blocks, which can lead to decreased fabrication yield and the designation of non-volatile memory devices as abnormal, especially when defective guarantee blocks exceed the available redundancy blocks.
Innovation Solution
A chip tester and test method that manage semiconductor memory devices by detecting defective blocks, comparing the number of available redundancy blocks with defective guarantee blocks, and reallocating redundancy blocks to ensure that defective guarantee blocks are replaced, thereby maintaining the device as a normal memory device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundancy blocks are allocated to replace defective normal blocks, then the reliability of normal blocks is improved, but the availability of redundancy blocks for guarantee blocks decreases
Solution Approach 1:
The patent implements a dynamic allocation system where redundancy block assignments are not fixed but can be adjusted based on test results. The determination unit dynamically reassigns redundancy blocks from defective normal blocks to guarantee blocks when needed, making the system adaptable to actual defect distributions rather than following a static allocation scheme
Solution Approach 2:
The system changes the allocation parameter (which blocks are assigned to which redundancy blocks) based on test outcomes. When guarantee blocks are found defective, the system modifies the allocation parameters by canceling previous assignments and creating new ones, allowing flexible redistribution of redundancy resources to maintain overall device reliability
2Reliability
If more redundancy blocks are provided for guarantee blocks, then the reliability of guarantee blocks is improved, but the device complexity increases
Solution Approach 1:
The system performs self-testing and self-diagnosis through the test unit that automatically detects defective blocks. The determination unit then automatically determines and executes reallocation decisions without external intervention, allowing the device to manage its own redundancy resources intelligently based on actual conditions rather than requiring complex external management systems
Solution Approach 2:
The system implements a feedback loop where test results about block defects are fed back to the determination unit, which then adjusts redundancy allocations accordingly. This closed-loop control enables the system to respond to actual defect conditions and optimize redundancy usage dynamically, reducing the need for excessive redundancy blocks while maintaining reliability
3Productivity
If defective blocks are detected and replaced early in the process, then the fabrication yield is improved, but the testing time and complexity increase
Solution Approach 1:
The system performs comprehensive testing of all blocks including guarantee blocks before final device designation. By conducting this preliminary detection and reallocation process during manufacturing testing rather than during customer use, the system prevents future failures and ensures high yield without requiring extended operational testing time
Solution Approach 2:
The test unit and determination unit serve multiple functions: they test both normal and guarantee blocks, detect various types of defects, manage redundancy allocations for different block types, and determine overall device status. This multi-functional approach consolidates what could be separate complex processes into a unified efficient system
Data Source
AI summary
A chip tester includes a test unit suitable for performing a test on guarantee blocks and for detecting at least one second defective block from the guarantee blocks, a storage unit suitable for storing repair information, a determination unit suitable for comparing the number of available redundancy blocks, which are not allocated for first defective blocks, with the number of at least one second defective block, by referring to the repair information, and a guarantee block management unit suitable for updating the repair information to cancel allocation of at least one of a plurality of redundancy blocks based on a result of the comparison of the determination unit.