Bit-line Sense Amplifier Driving-Voltage Control Circuit for Micro-bridge Defect Detection
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Solution Overview
Problem
Semiconductor memory devices face issues with read errors due to unwanted current paths like micro-bridges, leading to incorrect identification of defective chips, as existing testing methods may incorrectly flag chips without micro-bridge defects as bad due to leakage currents during long charge-sharing periods.
Innovation Solution
A bit-line sense amplifier with a driving-voltage control circuit generating specific test driving voltages allows precise detection of micro-bridge defects by preventing leakage currents, using different voltage levels for P-type and N-type sense amplifiers based on charge-sharing states, and employing high and low supply-voltage circuits to manage these voltages effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a long charge sharing period is used during bit-line micro-bridge testing, then the detection precision is improved, but leakage current increases causing false positives
Solution Approach 1:
The patent applies dynamics by making the driving voltage adjustable and time-dependent. The driving voltage control circuit dynamically changes the voltage level applied to the sense amplifier during different phases of the testing process, allowing optimization of both detection precision and leakage current suppression.
Solution Approach 2:
The patent changes the electrical parameter (driving voltage level) of the sense amplifier during testing. By adjusting the driving voltage to different levels based on the testing stage, the system achieves precise defect detection while minimizing leakage current effects that cause false positives.
2Device complexity
If conventional testing methods are used, then the testing process is simple, but false identification of defective chips occurs
Solution Approach 1:
The patent introduces a driving voltage control circuit as an intermediary component between the test signal source and the sense amplifier. This intermediary actively manages the voltage levels to prevent leakage current-induced false positives, thereby improving chip identification accuracy without significantly complicating the overall testing architecture.
3Reliability
If high driving voltage is applied to prevent leakage current, then false positives are reduced, but normal operation is affected
Solution Approach 1:
The system dynamically adjusts the driving voltage based on the operational mode (testing vs. normal operation). During micro-bridge testing, the voltage is set to levels that prevent leakage current and false positives. During normal operation, the voltage returns to standard levels, ensuring proper functionality. This temporal separation of voltage conditions resolves the contradiction.
Solution Approach 2:
The driving voltage control circuit periodically switches between different voltage levels corresponding to different operational modes. The voltage is adjusted to high levels during testing phases to reduce false positives, and returned to normal levels during operational phases, creating a periodic voltage profile that satisfies both requirements.
Data Source
AI summary
The bit-line sense amplifier includes a driving-voltage control circuit and an amplifier. The driving-voltage control circuit generates a first test driving voltage having a voltage level of a pre-charge voltage, a second test driving voltage having a voltage level of a pre-charge voltage added by a voltage difference between a bit-line and a complementary bit-line, and a third test driving voltage having a voltage level of a pre-charge voltage subtracted by the voltage difference in a test mode. The amplifier senses and amplifies a voltage difference between the bit-line and the complementary bit-line.