Semiconductor Memory Retention Time Testing Method
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Solution Overview
Problem
Current test methods for semiconductor devices with variable retention time (VRT) memory cells are inaccurate, time-consuming, and fail to accurately determine the minimum retention time and position of failing memory cells due to poor correlation and increased test noise, especially under varying temperature conditions.
Innovation Solution
A test method that presets retention time ranges and step sizes to form test values for sequential testing in ascending and descending orders, recording positions and values of memory cells with retention times less than the test values, and combining data to determine failing memory cells, thereby improving accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional test methods are used for VRT memory cells, then testing can be performed, but measurement precision and accuracy of retention time determination deteriorate due to poor correlation and increased test noise
Solution Approach 1:
The test process is divided into multiple sequential testing stages with different test values. Instead of using a single test value, the method segments the retention time measurement into multiple discrete test points, allowing for more precise determination of the retention time distribution characteristics and reducing the impact of test noise on measurement accuracy.
Solution Approach 2:
The method performs preliminary testing with multiple test values before final determination. By conducting tests with different test values in advance and analyzing the results to identify the retention time distribution range, the system prepares optimal test parameters that improve subsequent measurement precision and reduce test noise effects.
2Measurement precision
If multiple test values are used to improve accuracy, then retention time measurement precision improves, but test time increases
Solution Approach 1:
The method performs preliminary testing with multiple test values to determine the retention time distribution range and characteristics before final measurement. This preliminary action identifies the optimal test value range, allowing subsequent tests to focus only on relevant values, thereby improving accuracy while limiting additional time consumption.
Solution Approach 2:
The method uses a limited number of strategically selected test values rather than exhaustive testing. By applying partial action with carefully chosen test points that cover the critical retention time range, the system achieves sufficient measurement precision without the time cost of complete exhaustive testing.
3Measurement precision
If comprehensive test data is collected to improve accuracy, then measurement precision improves, but memory usage increases
Solution Approach 1:
The method extracts and retains only the essential test data needed for accurate retention time determination. Instead of storing all raw test data, the system extracts key parameters such as the retention time distribution range and characteristic values, significantly reducing memory usage while preserving measurement precision.
Solution Approach 2:
The method discards redundant test data that does not contribute to retention time measurement accuracy. By selectively retaining only useful data points that provide information about the retention time distribution, the system reduces memory storage requirements while maintaining measurement precision through recovery of essential measurement characteristics.
Data Source
AI summary
The present disclosure provides a test method and a test apparatus for a semiconductor device. The test method includes: forming a plurality of test values based on a first retention time range and a first step size, and sequentially testing a plurality of memory cells in the semiconductor device based on the plurality of test values in ascending order; determining, during tests corresponding to each test value, a memory cell whose retention time is less than the test value, and recording a position and corresponding test value of the memory cell whose retention time is less than the test value, to form first test data; a similar method is applied to form second test data; and determining, based on the first test data and the second test data, positions and corresponding test values of memory cells whose retention times fail to pass the tests.