Semiconductor Memory Device Bit Line Control Voltage Supply Unit
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Solution Overview
Problem
Existing semiconductor memory devices face inefficiencies in providing a ground voltage during soft programming operations, leading to delayed ground voltage supply and complex control signal requirements, which prolongs the data erase process.
Innovation Solution
A semiconductor memory device and method that includes a bit line control voltage supply unit to provide a ground voltage directly to the bit line during soft programming, and a data erase method that electrically isolates the bit line from the page buffer to quickly apply a ground voltage, reducing the time required for the data erase operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the ground voltage is supplied through the page buffer to the bit line, then the ground voltage can be provided to the memory cell channel, but the supply time is delayed due to the large loading value of the bit line
Solution Approach 1:
The invention extracts the ground voltage supply function from the page buffer by introducing a dedicated bit line control voltage supply unit. This separate unit directly supplies ground voltage to the bit line without going through the page buffer, thereby eliminating the delay caused by the page buffer's control signals and the bit line's large loading value.
Solution Approach 2:
The invention segments the ground voltage supply path into two independent paths: one through the page buffer for normal operations and another direct path through the bit line control voltage supply unit for soft programming operations. This segmentation allows the ground voltage to be supplied more quickly during soft programming by bypassing the page buffer.
2Ease of operation
If the page buffer is used to provide ground voltage, then the ground voltage can be supplied to the memory cell, but a large number of control signals are required to control the page buffer
Solution Approach 1:
The invention extracts the ground voltage supply control function from the page buffer by introducing a dedicated bit line control voltage supply unit. This unit requires fewer control signals compared to the page buffer, thereby simplifying the control signal management during soft programming operations.
3Manufacturing precision
If soft programming operation is performed after erase operation, then the threshold voltage distribution can be formed at desired level, but the overall data erase time is prolonged
Solution Approach 1:
The invention extracts the ground voltage supply function from the page buffer to create a dedicated bit line control voltage supply unit. This allows the soft programming operation to be performed more quickly by directly supplying ground voltage to the bit line, thereby reducing the overall data erase time while maintaining the desired threshold voltage distribution precision.
Data Source
AI summary
A semiconductor memory device includes: a plurality of memory cells coupled in series between a bit line and a source line; and a bit line control voltage supply unit configured to provide a control voltage to the bit line according to an operation mode, wherein the bit line control voltage supply unit provides a control voltage having a ground voltage level to the bit line during a soft programming operation.