Twin-Bit Cell With Al2O3 Insert For Gate Segmentation
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Solution Overview
Problem
Conventional methods for manufacturing twin-bit cell structures in semiconductor devices face challenges in scaling down due to difficulties in controlling gates independently and forming insulating regions, limiting the further reduction of device size and increasing circuit density.
Innovation Solution
A method involving the formation of a polysilicon gate structure over a gate dielectric layer, followed by the creation of undercut regions and the deposition of aluminum oxide material with nanocrystalline silicon sandwiched between aluminum oxide layers, which is then selectively etched to form an insert region, allowing for further scaling and improved charge storage capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional manufacturing methods are used for twin-bit cell structures, then existing process compatibility is maintained, but device size cannot be further reduced and circuit density improvement is limited
Solution Approach 1:
The gate structure is divided into multiple independently controllable gates (first gate, second gate, third gate, fourth gate) formed through selective etching of the aluminum oxide material. This segmentation allows each gate to be controlled independently, enabling twin-bit cell operation while reducing the overall device size and increasing circuit density.
Solution Approach 2:
The patent introduces a vertical dimension by forming aluminum oxide material overlying the gate polysilicon structure and creating insert regions through selective etching. This three-dimensional structure allows for more compact device layout, enabling further scaling while maintaining independent gate control for twin-bit functionality.
2Productivity
If device size is reduced to increase circuit density, then more devices can be fabricated on each wafer, but independent gate control becomes difficult to achieve
Solution Approach 1:
The gate structure is segmented into multiple independently controllable gates (first gate, second gate, third gate, fourth gate) formed through selective etching of the aluminum oxide material. This segmentation allows each gate to be controlled independently, enabling twin-bit cell operation while reducing the overall device size and increasing circuit density.
Solution Approach 2:
The aluminum oxide material is selectively etched to create insert regions with specific local properties that enable independent gate control. The first and second aluminum oxide layers are differentially removed to form distinct gate regions, providing local quality variations that facilitate precise independent control of each gate despite reduced device dimensions.
3Reliability
If aluminum oxide material with nanocrystalline silicon is deposited and selectively etched, then twin-bit cell structure with independent gate control is achieved, but process complexity increases
Solution Approach 1:
The aluminum oxide material with nanocrystalline silicon is deposited in advance overlying the gate polysilicon structure, creating a pre-formed layer that will be selectively etched later. This preliminary action simplifies the overall process by establishing the gate structure framework before final patterning, reducing the complexity of subsequent steps while ensuring reliable independent gate control.
Solution Approach 2:
The aluminum oxide material with nanocrystalline silicon acts as an intermediary layer that facilitates the formation of independent gates. This intermediate material is selectively etched to create the insert regions, serving as a mediator between the gate polysilicon structure and the final twin-bit cell configuration, thereby simplifying the transition from single-layer to multi-gate structure.
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 approach enables the reliable formation of twin-bit cell structures with increased scalability and cost-effective implementation, allowing for more efficient charge storage and improved performance in non-volatile memory devices.
Implementation Method 1
the method subjects the gate polysilicon structure to an oxidizing environment to cause formation of a first silicon oxide layer overlying the gate polysilicon structure
Implementation Method 2
The aluminum oxide material is subjected to a selective etching process to form an insert region in a portion of the undercut region while the insert region remains filled with the aluminum oxide material
Data Source
AI summary
A method and system for forming a non-volatile memory structure. The method includes providing a semiconductor substrate and forming a gate dielectric layer overlying a surface region of the semiconductor substrate. A polysilicon gate structure is formed overlying the gate dielectric layer. The method subjects the polysilicon gate structure to an oxidizing environment to cause formation of a first silicon oxide layer overlying the polysilicon gate structure and formation of an undercut region underneath the polysilicon gate structure. An aluminum oxide material is formed overlying the polysilicon gate structure filling the undercut region. In a specific embodiment, the aluminum oxide material has a nanocrystalline silicon material sandwiched between a first aluminum oxide layer and a second aluminum oxide layer. The aluminum oxide material is subjected to a selective etching process while maintaining the aluminum oxide material in an insert region in a portion of the undercut region. The method forms a sidewall structure overlying a side region of the polysilicon gate structure.