3D NAND Select Cells for Groove-Free Memory String Control
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Solution Overview
Problem
The fabrication of 3D NAND flash memory devices is complicated by the need for openings or grooves in the stack structure, increasing process time and cost.
Innovation Solution
A memory system with a semiconductor layer and memory array, featuring memory strings connected by select cells with different threshold voltages, allowing selective control of memory strings using varying voltages to simplify processes and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If openings or grooves are made in the stack structure to control memory strings, then selective control of memory strings is achieved, but the fabrication process becomes complicated and process time increases
Solution Approach 1:
The patent applies parameter changes by utilizing different threshold voltage parameters of transistors to achieve selective control of memory strings. Instead of modifying the physical structure through grooves, the invention changes the electrical parameter (threshold voltage) of transistors to differentiate and control individual memory strings, thereby simplifying the fabrication process while maintaining selective control capability.
2Ease of operation
If openings or grooves are made in the stack structure to control memory strings, then selective control of memory strings is achieved, but process cost increases
Solution Approach 1:
The invention reduces process cost by changing the threshold voltage parameter of transistors instead of performing additional fabrication steps like creating grooves. This parameter-based control method eliminates complex manufacturing steps, thereby reducing process cost while achieving the same selective control function.
3Adaptability or versatility
If multiple transistors with different threshold voltages are used in select cells, then selective control of memory strings is enabled, but device structure becomes more complex
Solution Approach 1:
The patent applies local quality by assigning different threshold voltage characteristics to specific transistors within select cells. Each transistor is designed with a particular threshold voltage property that enables it to respond to specific voltage levels, allowing selective control of memory strings through localized electrical property differentiation rather than structural complexity.
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
Enables selective control of memory strings, simplifying the manufacturing process and reducing costs by eliminating the need for complex grooving of stack structures.
Implementation Method 1
The select cell includes first transistors with a first threshold voltage and second transistors with a second threshold voltage, the first threshold voltage being different from the second threshold voltage
Data Source
AI summary
A memory, a controlling method thereof, a memory system and an electronic device are disclosed. The memory can include a semiconductor layer and a memory array disposed on the semiconductor layer. The memory array can include a plurality of memory strings connected with the same bit line. Each memory string can include a memory cell and a select cell connected on at least one side of the memory cell. The select cell can include a first kind of transistors with a first threshold voltage and a second kind of transistors with a second threshold voltage. The first kind of transistors can be connected with the second kind of transistors. The first threshold voltage can be different from the second threshold voltage. Different memory strings can be controlled to be on or off to realize selective controlling functions for a plurality of memory strings connected with the same bit line.