NOR Flash Memory Short Circuit Detection via P-type Well Leakage
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Solution Overview
Problem
NOR flash memory systems face defects such as word line shorts with bit lines or source lines, leading to data unrecoverability and the need for specialized methods to detect and manage these defects, as existing error correction mechanisms are insufficient.
Innovation Solution
A method involving a first detection process where a positive voltage is applied to the P-type well of the flash memory array, with all word lines grounded and bit lines and the source line floated, to determine if a leakage current exceeds a threshold, indicating a short-circuit, followed by subsequent processes to identify specific short-circuited lines and facilitate data transfer to a redundancy array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a positive voltage is applied to the P-type well to detect leakage current, then the detection capability for short-circuited word lines is improved, but the complexity of the detection process increases
Solution Approach 1:
The detection process is divided into multiple sequential stages: first applying positive voltage to the P-type well to detect overall leakage, then selectively grounding specific word lines to isolate and identify the exact location of short-circuited lines. This segmentation transforms a complex single-step detection into manageable sequential steps.
Solution Approach 2:
The P-type well serves as an intermediary element that enables indirect detection of word line short circuits. By monitoring leakage current through the P-type well rather than directly measuring each word line, the system simplifies the detection mechanism while maintaining high detection capability.
2Measurement precision
If word lines are grounded and bit lines and source line are floated during detection, then the accuracy of identifying short-circuited word lines is improved, but the ease of operation decreases
Solution Approach 1:
The detection method applies preliminary actions by pre-configuring the voltage states of various lines (grounding word lines, floating bit lines and source line) before the actual leakage measurement. This preliminary setup creates optimal conditions for accurate detection while establishing a systematic approach that simplifies subsequent identification steps.
3Reliability
If the detection method identifies specific short-circuited lines, then the reliability of data protection is improved, but the time required for detection increases
Solution Approach 1:
The detection process employs periodic action by systematically cycling through different word line grounding configurations. Each cycle tests specific combinations of word lines, allowing comprehensive identification of short-circuited lines through repeated, structured measurements rather than exhaustive single-step testing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the detection of defective flash memory arrays, allowing for data protection and transfer of data from defective arrays to redundancy arrays, ensuring data integrity and recoverability.
Implementation Method 1
determining whether a leakage current flowing through the P-type well exceeds a leakage threshold
Data Source
AI summary
A method for detecting a flash memory array includes a plurality of word lines, a plurality of bit lines, and a source line, includes executing a first detection process. The first detection process includes: applying a first positive voltage to a P-type well of the flash memory array; applying a ground to all the word lines; floating the bit lines and the source line; determining whether a leakage current flowing through the P-type well exceeds a leakage threshold; and when the leakage current exceeds the leakage threshold, determining that at least one of the word lines is short-circuited with at least one of the bit lines or the source line.