Semiconductor Storage Device Program Voltage Control
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Solution Overview
Problem
Existing semiconductor storage devices face performance deterioration during interrupted write operations due to excessive increase in threshold voltage, leading to dispersion in threshold voltage distribution and potential erroneous readings.
Innovation Solution
The semiconductor storage device adjusts the program voltage increase from DVPGM1 to DVPGM2, a smaller positive amount, after resuming a write operation that was interrupted, to prevent threshold voltage deterioration and maintain a narrower threshold voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the program voltage is increased by a fixed amount DVPGM1 each time the program loop is repeated, then the write operation speed is improved, but the threshold voltage distribution becomes dispersed leading to erroneous readings
Solution Approach 1:
The patent applies dynamics by making the program voltage increment amount variable rather than fixed. The control circuit dynamically adjusts the increment amount between program loops based on whether an interrupt operation occurred, transitioning from a static DVPGM1 to a adaptive scheme using either DVPGM1 or DVPGM2, thereby optimizing both speed and precision under different operational conditions
Solution Approach 2:
The patent changes the parameter of program voltage increment amount based on operational context. When an interrupt operation occurs, the increment amount is changed from DVPGM1 to DVPGM2 for the first program loop after interruption, preventing excessive threshold voltage increase and maintaining distribution precision while still allowing faster increments during normal operation
2Productivity
If the program voltage is increased by a large amount to complete write operation faster, then the productivity is improved, but the threshold voltage increases excessively causing dispersion
Solution Approach 1:
The patent applies preliminary anti-action by anticipating the potential harm of excessive threshold voltage increase after an interrupt operation. The control circuit proactively reduces the program voltage increment amount to DVPGM2 in the first program loop after interruption, preventing the harmful effect of excessive threshold voltage dispersion before it occurs, thereby maintaining read operation accuracy
3Manufacturing precision
If the program voltage increment is reduced to maintain narrow threshold voltage distribution, then the threshold voltage precision is improved, but the write operation time increases
Solution Approach 1:
The patent uses dynamics to adjust the program voltage increment amount based on operational context. During normal operation without interrupts, the system uses the larger increment DVPGM1 for faster writing. When an interrupt occurs, it dynamically switches to the smaller increment DVPGM2 only when necessary, thereby minimizing time loss while maintaining precision when required
Data Source
AI summary
A semiconductor storage device includes a memory cell connected to a word line, and a control circuit configured to execute a write operation that repeats a program loop including a program operation of applying a program voltage to the word line and a verification operation to be executed after the program operation. The control circuit, during the write operation, increases the program voltage by a first amount each time the program loop is repeated, and after the write operation is interrupted and resumed, changes the increase in the program voltage from the first amount to a second amount, which is a positive number smaller than the first amount.