Nonvolatile Memory Program Method Discharging Unselected Block Charges
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonvolatile memory devices experience a 'under program' phenomenon due to leakage current in unselected memory cell blocks, causing a drop in verify voltage and lowering the threshold voltage of target program cells during programming and verification operations.
Innovation Solution
The method involves executing a program operation on a selected memory cell block, discharging electric charges from the channel of unselected memory cell blocks, and grounding the common source line and variable voltage input terminal to prevent leakage current and maintain the verify voltage level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If program operation is executed on a selected memory cell block, then the target program cells are programmed, but leakage current is generated in unselected memory cell blocks causing verify voltage drop
Solution Approach 1:
The patent extracts and removes the harmful leakage current effect by discharging electric charges from the channel of unselected memory cell blocks before verify operation. This is achieved by applying a discharge voltage to the word line of unselected blocks, which actively removes accumulated charges that would otherwise cause leakage current and verify voltage drop.
Solution Approach 2:
The patent applies preliminary anti-action by performing charge discharge operation on unselected memory cell blocks before the verify operation. This preliminary action counteracts the potential harmful effect of leakage current generation, ensuring that the verify voltage remains stable and the threshold voltage programming precision is maintained.
2Measurement precision
If verify operation is performed on selected memory cell block, then programming accuracy is checked, but the threshold voltage of target program cells is lowered due to verify voltage drop
Solution Approach 1:
The patent removes the harmful effect causing threshold voltage lowering by extracting and discharging electric charges from unselected memory cell blocks. This elimination of charge accumulation prevents the verify voltage drop that would otherwise cause the under program phenomenon and threshold voltage instability.
Solution Approach 2:
The patent performs the charge discharge operation as a preliminary action before the verify operation. By clearing charges from unselected blocks in advance, the system ensures that the verify operation can be performed with accurate voltage levels, maintaining both measurement precision and threshold voltage reliability.
3Productivity
If unselected memory cell blocks are left charged, then program operation can be executed efficiently, but leakage current reduces the verify voltage level
Solution Approach 1:
The patent extracts harmful electric charges from unselected memory cell blocks to eliminate leakage current. This removal of excess charges prevents energy loss through leakage while maintaining efficient program operation, as the charge discharge is performed selectively only on unselected blocks.
Solution Approach 2:
The patent discards harmful electric charges accumulated in unselected memory cell blocks by applying discharge voltage. This selective discarding of charges eliminates the harmful leakage current effect while preserving the program operation efficiency, as the discharged blocks are ready for subsequent operations without residual charge interference.
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
This approach effectively prevents the drop in verify voltage, thereby preventing the 'under program' phenomenon and ensuring accurate threshold voltage maintenance for target program cells.
Implementation Method 1
discharging electric charges charged to a channel of memory cell strings included in unselected memory cell blocks
Data Source
AI summary
A program method of nonvolatile memory devices, which can solve an under program problem by preventing a drop of a verify voltage in the program, and verify operations. According to an aspect of the method, a program operation is performed on a selected memory cell block. Electric charges charged to a channel of memory cell strings included in unselected memory cell blocks are discharged. A verify operation is performed on the selected memory cell block.