Semiconductor Memory Device Pre-Drain Voltage Initialization
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Solution Overview
Problem
Semiconductor memory devices experience a program disturbance phenomenon in unselected memory strings during programming operations, where the potential levels of unselected memory strings are not properly initialized, leading to potential errors in data retention and storage.
Innovation Solution
A semiconductor memory device with a control logic that performs a verify operation and applies a pre-drain select line voltage to the drain select lines of both selected and unselected memory blocks, ensuring that the potential levels of memory strings are initialized to prevent program disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If program operation is performed on selected memory block, then data is programmed into selected memory block, but program disturbance occurs in unselected memory strings due to improper initialization of potential levels
Solution Approach 1:
The patent applies a pre-drain select line voltage to drain select lines of both selected and unselected memory blocks before performing the program operation. This preliminary action initializes the potential levels of memory strings in unselected blocks, preventing program disturbance from occurring during the subsequent programming process.
Solution Approach 2:
The patent applies a pre-drain select line voltage to counteract the potential program disturbance effect before it can occur. By pre-initializing the potential levels of memory strings in unselected blocks, the harmful effect of program disturbance is prevented in advance during the program operation.
2Measurement precision
If verify operation is performed on all memory blocks, then programming accuracy is ensured, but operation time increases due to additional verification steps
Solution Approach 1:
The patent applies the pre-drain select line voltage to both selected and unselected memory blocks, which is more extensive than traditionally necessary. This excessive action ensures that all memory strings are properly initialized, preventing any potential program disturbance in unselected blocks while maintaining programming verification accuracy.
Data Source
AI summary
There are provided a semiconductor memory device and an operating method thereof. A semiconductor memory device includes a memory cell array including a plurality of memory blocks, a peripheral circuit for performing a program operation on a selected memory block among the plurality of memory blocks, and a control logic for controlling the peripheral circuit to perform the program operation. The control logic controls the peripheral circuit to perform a verify operation during the program operation and then apply a pre-drain select line voltage to drain select lines of the selected memory block and unselected memory blocks.