Floating-Body NAND String for Non-Volatile Data Retention
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Solution Overview
Problem
Existing semiconductor memory technologies face challenges in efficiently storing and maintaining data without power, particularly in volatile memory devices like DRAM, which lose data when power is interrupted.
Innovation Solution
The development of a semiconductor memory cell utilizing an electrically floating body transistor, which includes a floating body region that can be charged to indicate the state of the memory cell, and a collector region to maintain this charge, thereby maintaining the state of the semiconductor memory cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DRAM cells are used, then data storage is achieved, but data is lost when power is not continuously supplied
Solution Approach 1:
The patent extracts the capacitor component from the conventional 1T/1C memory cell structure, eliminating the need for continuous power supply to maintain data. The floating body region replaces the capacitor's charge storage function, enabling capacitorless DRAM operation that retains data without continuous power.
Solution Approach 2:
The patent changes the fundamental operating parameter from capacitor-based charge storage to floating body charge storage. By utilizing the electric field effect in a floating body region, the memory cell achieves non-volatile operation without requiring the continuous power supply that conventional DRAM needs to maintain capacitor charges.
2Area of moving object
If capacitorless memory cells are used, then cell size is reduced, but data retention capability is compromised
Solution Approach 1:
The floating body region serves dual functions: it acts as both the charge storage element and the transistor body, eliminating the need for separate capacitor structures. This self-service approach enables the cell to maintain data retention capability while achieving reduced cell size compared to conventional 1T/1C designs.
3Reliability
If floating body transistor is used, then non-volatile storage is achieved, but device complexity increases
Solution Approach 1:
The floating body region performs multiple functions simultaneously: it serves as the transistor body, the charge storage element, and the potential well for charge confinement. This multi-functionality reduces overall device complexity compared to designs that would require separate components for each function, despite achieving non-volatile storage capability.
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 solution enables the creation of a semiconductor memory array with stable states that can maintain data without continuous power supply, improving data retention and reducing power consumption.
Implementation Method 1
a floating body region that can be charged to a level indicative of a state of the semiconductor memory cell
Implementation Method 2
a third region in electrical contact with the floating body region, spaced apart from the first and second regions and having the second conductivity type, wherein the third region is configured to function as a collector region to maintain a charge of the floating body region
Data Source
AI summary
NAND string configurations and semiconductor memory arrays that include such NAND string configurations are provided. Methods of making semiconductor memory cells used in NAND string configurations are also described.