Memory Device Test Method for Margin Condition Fault Coverage
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Solution Overview
Problem
In dynamic random access memory devices, the fault coverage of test actions is reduced due to the lack of retesting under margin conditions for one-time programmable memory, which can lead to undetected aberrances during the embedding process.
Innovation Solution
A test method that disables and enables the redundancy function in memory arrays, writes complementary data, and reads redundancy information under both normal and margin conditions to detect operational integrity, thereby enhancing fault coverage without significantly increasing test time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If test actions under margin condition are not performed on one-time programmable memory, then test time is reduced, but fault coverage is reduced
Solution Approach 1:
The patent applies dynamics by making the test conditions adjustable and variable. The test system dynamically switches between normal condition mode and margin condition mode, allowing the testing to adapt to different requirements. This resolves the contradiction by enabling comprehensive testing (high fault coverage) while maintaining efficient testing options (low test time) through conditional execution.
Solution Approach 2:
The patent changes the testing parameters by introducing margin condition parameters (such as margin readout voltage) alongside normal condition parameters. By varying these parameters and selecting appropriate test conditions based on requirements, the system achieves high fault coverage when needed while allowing faster testing when margin condition testing is not required.
2Device complexity
If only normal condition reading is performed on one-time programmable memory, then test complexity is reduced, but detection accuracy is reduced
Solution Approach 1:
The test system dynamically adjusts its operation mode between normal condition reading and margin condition reading. This dynamic capability allows the system to maintain simplicity by default (using only normal condition reading) while providing the option to enhance detection accuracy by switching to margin condition reading when higher precision is required.
Solution Approach 2:
The patent introduces margin condition parameters as an additional testing parameter set. By changing from normal condition parameters to margin condition parameters, the system can enhance detection accuracy without permanently increasing test complexity. The complexity only increases when the margin condition testing is actually executed.
Data Source
AI summary
A test method for a memory device including the following steps is provided. A redundancy function of the memory device is disable and a first data is written to a first memory array. The redundancy function of the memory device is enabled and a second data is written to a second memory array. The first data and the second data are complementary. A redundancy information is read from a non-volatile memory block according to a margin condition and the second memory array is read based on the redundancy information to obtain a first readout data. A first test result is generated by comparing the second data and the first readout data. The second memory array includes a part of memory cells of the first memory array and at least one redundancy memory cell.