NAND Page Buffer Sensing for Sense Amplifier Variation
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Solution Overview
Problem
The integration of semiconductor memory devices, such as vertical NAND flash memory, leads to significant deviations in the operating characteristics of sense amplifiers, causing errors in data read and verification due to variations in the sense amplifier's voltage amplification capabilities.
Innovation Solution
A method is implemented to accurately operate semiconductor memory devices by detecting deviations in the operating characteristics of first and second sense amplifiers, applying a first voltage to a sensing node, and sequentially repeating internal operations for different times based on these deviations, using both coarse and fine sensing amplifiers to adjust the threshold voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of layers in vertical NAND flash memory is increased to improve integration, then storage capacity is improved, but deviation in operating characteristics of sense amplifiers increases causing read/verification errors
Solution Approach 1:
The page buffer is divided into multiple independent sense amplifiers (first sense amplifier, second sense amplifier, etc.), each capable of independently sensing data from different memory cells. This segmentation allows each sense amplifier to be individually calibrated and compensated for its specific operating characteristics, thereby maintaining data read accuracy even as the number of memory layers increases
Solution Approach 2:
The invention changes the operating parameters of sense amplifiers by applying different sensing times and voltages to different sense amplifiers based on their individual characteristics. By adjusting these parameters dynamically, the system compensates for deviations in operating characteristics that arise from increased integration, ensuring reliable data reading across all sense amplifiers
2Measurement precision
If sensing operation time is extended to improve detection accuracy, then measurement precision is improved, but operating time increases and productivity decreases
Solution Approach 1:
The sensing time for each sense amplifier is made dynamic rather than static. The control circuit adjusts the sensing time of each sense amplifier individually based on its specific operating characteristics and the detected deviation. This allows each sense amplifier to use the minimum necessary sensing time to achieve accurate detection, thereby improving overall operation speed while maintaining sensing accuracy
Solution Approach 2:
The invention changes the sensing time parameter for different sense amplifiers based on their individual characteristics. By optimizing this parameter for each sense amplifier, the system achieves the right balance between measurement precision and productivity, avoiding unnecessary extension of sensing time while ensuring accurate data reading
Data Source
AI summary
The present disclosure relates to semiconductor memory devices and methods of operating a semiconductor memory device. One example method includes setting a sensing node of a page buffer to a first voltage, detecting a deviation in operating characteristics of a first sense amplifier and a second sense amplifier with respect to the first voltage, and sequentially repeating a first internal operation for at least two different operating times in the first sense amplifier, the second sense amplifier, or the first sense amplifier and the second sense amplifier based on the deviation in operating characteristics of the first sense amplifier and the second sense amplifier.