Nonvolatile Memory Segmentation for High Stack Reliability
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Solution Overview
Problem
As the number of channel structures in nonvolatile memory devices increases, operational issues arise due to the complexity of the high stack structure in NAND-type flash memory, affecting the performance and reliability of these devices.
Innovation Solution
The implementation of a nonvolatile memory design that includes a first and second memory cell array with distinct selection transistors, each programmed with different threshold voltages using separate program commands, and read commands, allowing for improved control and operation of string selection transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of channel structures is increased to improve storage capacity, then the storage capacity is improved, but the operational reliability deteriorates due to complexity of high stack structure
Solution Approach 1:
The memory device is divided into multiple independent memory blocks (first memory block, second memory block), each with its own selection transistor and string selection line. This segmentation allows each block to be independently controlled and programmed with different threshold voltages, improving operational reliability while maintaining high storage capacity through the combined channels of all blocks.
Solution Approach 2:
Different threshold voltages are applied to different selection transistors (first threshold voltage to first selection transistor, second threshold voltage to second selection transistor). This local differentiation allows optimization of read and program operations for each block independently, enhancing overall device reliability while supporting high capacity through multiple channels.
2Quantity of substance
If the number of channel structures is increased to improve storage capacity, then the storage capacity is improved, but the device complexity increases due to high stack structure
Solution Approach 1:
The complex multi-channel structure is segmented into multiple independent memory blocks, each with simplified control logic. Each block has its own selection transistor and can be independently programmed, which simplifies the control architecture while enabling high storage capacity through parallel operation of multiple blocks.
Solution Approach 2:
The invention uses different threshold voltage parameters (first threshold voltage, second threshold voltage) to differentiate and control multiple selection transistors. This parameter-based control simplifies the management of complex multi-channel structures by using voltage levels as distinct identifiers and control mechanisms for each block.
3Ease of operation
If different threshold voltages are programmed to different selection transistors to improve operational control, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
Selection transistors are pre-programmed with different threshold voltages during manufacturing or initialization. This preliminary action establishes distinct operational characteristics for each block before actual memory operations, simplifying subsequent read and program operations while the programming complexity is confined to the initial setup phase.
Solution Approach 2:
The invention employs different voltage parameters (first program voltage, second program voltage) to program different threshold voltages in different selection transistors. This parameter differentiation provides clear control mechanisms for each block, improving ease of operation during normal use while the complexity of managing multiple parameters is handled through systematic programming procedures.
Data Source
AI summary
A nonvolatile memory may include; a first memory cell array including a first selection transistor connected to a first string selection line, a second memory cell array including a second selection transistor connected to a second string selection line and spaced apart from the first string selection line by a first cutting line, and a peripheral circuit. The peripheral circuit may provide a first program voltage to the first selection transistor, provide a second program voltage to the second selection transistor different from the first program voltage, program the first selection transistor with a first threshold voltage in response to the first program voltage, and program the second selection transistor with a second threshold voltage level greater than the first threshold voltage in response to the second program voltage.