Non-volatile Memory Device Reducing Program Disturb via Bit Line Segmentation
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Solution Overview
Problem
Non-volatile semiconductor memory devices using the 2T FN type EEPROM suffer from program disturb, where unselected memory cells are inadvertently programmed, leading to reliability issues.
Innovation Solution
A non-volatile semiconductor memory device and programming method that includes a memory cell block with serially connected memory and selection transistors, a bit line selection switch block, and a controller that applies specific voltages to disconnect unselected bit lines, preventing program disturb by ensuring only selected cells are programmed through controlled voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage is applied to program a selected memory cell, then the selected cell is programmed successfully, but unselected memory cells are also inadvertently programmed (program disturb)
Solution Approach 1:
The bit line selection is segmented into multiple groups, with each group controlled by a separate bit line selection switch. This segmentation allows independent control of different bit line groups, enabling precise selection of only the required bit lines for programming operations, thereby preventing program disturb in unselected cells
Solution Approach 2:
Before the programming operation is executed, the controller preliminarily activates the bit line selection switches to connect only the required bit lines to the bit line selection lines. This preliminary action ensures that unselected bit lines are already disconnected and floating, preventing any inadvertent programming of unselected memory cells
2Speed
If all bit lines are connected to global bit lines, then signal transmission is efficient, but program disturb occurs in unselected cells
Solution Approach 1:
The bit line selection switches dynamically change the connection state between bit lines and global bit lines based on the programming requirements. During programming, only the switches corresponding to selected bit lines are activated, creating a dynamic configuration that maintains efficient signal transmission for selected cells while isolating unselected cells to prevent program disturb
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
The solution effectively reduces program disturb by ensuring that only the intended memory cells are programmed, enhancing the reliability and accuracy of data storage in non-volatile semiconductor memory devices.
Implementation Method 1
A non-volatile semiconductor memory device using the EEPROM of the 2T FN type stores data by accumulating electrons on a floating gate by FN tunneling generated when a voltage of a certain condition is applied to a memory transistor
Data Source
AI summary
A non-volatile semiconductor memory device capable of reducing program disturb and a method of programming the same are provided. A bit line connected to a non-selected memory cell in the same block as a selected memory cell enters a floating state by inactivating a bit line selection switch, so that voltage levels of an first conductivity type channel and a source/drain terminal formed in a pocket second conductivity type well below a memory transistor have an intermediate level of a voltage level of a selection line and the pocket P type well. Therefore, program disturb caused by FN tunneling and junction hot electrons can be inhibited.