NAND Flash Charge Pump Word Line Short Detection
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Solution Overview
Problem
Memory devices face defects such as word line and bit line shorts, which can occur during manufacturing or over time, leading to operational failures and requiring improved testing methods to detect these defects effectively.
Innovation Solution
Implementing a charge pump circuit with a regulator and current sensing mechanisms to monitor voltage and duty cycle, allowing for real-time detection of word line shorts by tracking the activity of the control signal and counting clock cycles, thereby identifying defects in memory arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional manufacturing testing is used, then manufacturing process is simple, but defects like word line shorts remain undetected
Solution Approach 1:
The memory device performs self-diagnosis by using its own charge pump and control logic to detect defects in its word lines and bit lines, eliminating the need for external testing equipment and reducing overall system complexity
Solution Approach 2:
The defect detection mechanism uses feedback from charge pump current measurements and control signal monitoring to identify defects, allowing the system to adaptively respond to detected issues and improve reliability
2Reliability
If real-time defect detection is implemented, then operational reliability improves, but device complexity increases
Solution Approach 1:
The charge pump circuit serves multiple functions: it generates necessary voltages for memory operation and simultaneously acts as a sensing mechanism for defect detection, reducing the need for separate dedicated testing circuits
Solution Approach 2:
The defect detection functionality is merged with the existing charge pump and control logic, combining voltage generation and defect monitoring into a unified circuit architecture that minimizes additional complexity
3Measurement precision
If comprehensive defect monitoring is performed, then defect detection precision improves, but processing time increases
Solution Approach 1:
The defect detection operates continuously during normal memory operations rather than requiring separate testing phases, allowing real-time monitoring without significant time loss and maintaining high detection precision
Solution Approach 2:
The system performs preliminary defect detection during manufacturing and initialization phases, identifying and marking defective lines before full operation begins, which prevents time loss during active use
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 efficient detection of word line shorts and other defects, preventing operational failures and allowing for timely recovery or exclusion of defective memory planes, thus enhancing the reliability and performance of memory systems.
Implementation Method 1
determining whether a quantity of current generated by the pump circuit is greater than a specified threshold current
Data Source
AI summary
A memory device comprises a memory array; a word line driver circuit including a charge pump circuit configured to generate a program voltage target to be applied to a word line to program a memory cell of the memory array, and a control loop to activate the charge pump circuit using a control signal according to a comparison of a pump circuit output voltage to a specified duty cycle after the charge pump circuit output reaches the program voltage target, and provides an indication of current generated by the charge pump circuit according to the duty cycle; and logic circuitry that generates a fault indication when the current generated by the charge pump circuit is greater than a specified threshold current.