Semiconductor Memory ISPP Control for Threshold Voltage Uniformity
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Solution Overview
Problem
Nonvolatile memory apparatuses face challenges with low data processing speed and uneven threshold voltage distribution, necessitating improvements in operation speed and voltage distribution.
Innovation Solution
A semiconductor apparatus employing incremental step pulse programming (ISPP) with a control circuit, line driving circuit, and page buffer to manage program pulses, sensing threshold voltages, and adjusting bit line voltages based on threshold voltage levels, thereby improving threshold voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If nonvolatile memory apparatus is used to retain data without continuous power supply, then power consumption is reduced, but data processing speed becomes low
Solution Approach 1:
The programming process is divided into multiple incremental steps with increasing voltage levels. Instead of applying a single high-voltage pulse, the patent applies multiple program pulses with gradually increasing voltage levels (e.g., 20V, 22V, 24V, 26V) to achieve progressive threshold voltage adjustment, thereby improving programming speed and threshold voltage distribution while maintaining nonvolatile memory's low power consumption characteristic
Solution Approach 2:
The patent dynamically adjusts the bit line voltage based on the sensed threshold voltage of the memory cell. The page buffer increases the bit line voltage by an amount corresponding to the threshold voltage level, creating a dynamic programming process that adapts to the actual cell state, thereby optimizing programming speed and threshold voltage distribution
2Device complexity
If conventional programming method is used, then programming operation is simple, but threshold voltage distribution becomes uneven
Solution Approach 1:
The patent implements a feedback mechanism where the threshold voltage of the memory cell is sensed after each program pulse application. Based on the sensed threshold voltage, the bit line voltage is dynamically adjusted by the page buffer. This feedback loop ensures precise control over the threshold voltage programming process, achieving uniform threshold voltage distribution while maintaining manageable operational complexity through automated voltage adjustment
Solution Approach 2:
The patent changes multiple parameters during the programming process: (1) program pulse voltage level is incrementally increased across multiple steps, (2) bit line voltage is dynamically adjusted based on sensed threshold voltage, and (3) programming time is optimized through incremental steps. These parameter changes work together to achieve precise threshold voltage control and uniform distribution
Data Source
AI summary
A method for operating a semiconductor apparatus includes receiving a program command, applying a program pulse to a memory cell, sensing a threshold voltage of the memory cell, determining whether a program is completed according to a result of the sensing of the threshold voltage of the memory cell and increasing a voltage level of a bit line connected to the memory cell by a voltage level corresponding to a level of the threshold voltage of the memory cell according to a determination result in the determining of whether the program has completed.