Floating-Body DRAM Cell With Shared Control Electrode
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Solution Overview
Problem
Existing one-transistor DRAM cell devices with double-gate structures face challenges in miniaturization, leading to increased dispersion of threshold voltages and reduced sensing margins due to the need for independent lower gate electrodes, which complicates integration and operational efficiency.
Innovation Solution
A double-gate structure is implemented with a MOS-based gate electrode and a control electrode having a non-volatile memory function, where the control electrode is used to improve integration and sensing margins by adjusting charge storage, and the gate stack includes a tunneling insulating layer and a charge storage node, with the control electrode being electrically isolated from other devices to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If independent lower gate electrodes are used in each cell device to achieve double-gate structure, then sensing margin is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the lower gate electrodes of multiple adjacent cell devices into a single shared electrode structure. This allows the double-gate structure to maintain its sensing margin benefits while reducing the number of individual gate electrodes that need to be manufactured and controlled independently, thereby reducing device complexity and manufacturing difficulty.
Solution Approach 2:
The shared lower gate electrode serves multiple cell devices simultaneously, performing the same function (controlling the floating body potential) for multiple devices. This multi-functional approach reduces the overall number of components and simplifies the device structure while maintaining the enhanced sensing capabilities provided by the double-gate configuration.
2Productivity
If cell device size is reduced for miniaturization, then degree of integration is improved, but threshold voltage dispersion increases
Solution Approach 1:
The shared lower gate electrode structure ensures that multiple cell devices experience the same potential control conditions, which reduces threshold voltage dispersion even as device dimensions are reduced for miniaturization. This allows high degree of integration to be achieved while maintaining consistent electrical characteristics across devices.
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 configuration reduces dispersion of threshold voltages, improves sensing margins, and increases the degree of integration by allowing for common control electrodes in the cell array, while maintaining effective write, erase, and read operations.
Implementation Method 1
a control electrode (7) having a non-volatile memory function, wherein the control electrode (7) is used to improve integration and sensing margins by adjusting charge storage
Implementation Method 2
the gate stack includes a tunneling insulating layer and a charge storage node
Implementation Method 3
a drain 9 that is a bit line and a gate electrode 11 that is a word line are applied with voltages so that impact ionization can be easily formed. As a result, holes are generated in the floating body in the vicinity of the drain region 9
Data Source
AI summary
Provided are a high-performance one-transistor floating-body DRAM cell device and a manufacturing method thereof. The one-transistor floating-body DRAM cell device includes: a semiconductor substrate; a gate stack which is formed on the semiconductor substrate; a control electrode which is formed on the semiconductor substrate and surrounded by the gate stack; a floating body which is formed on the control electrode that is surrounded by the gate stack; source/drain which are formed at left and right sides of the floating body; an insulating layer which insulates the source/drain from the semiconductor substrate and the control electrode; a gate insulating layer which is formed on the floating body and the source/drain; and a gate electrode which is formed on the gate insulating layer. In the cell device having a double-gate structure, charges can be stored in a non-volatile manner by the control electrodes, so that it is possible to improve a degree of integration of devices, a uniformity of characteristic, and a sensing margin.