Stacked Nanosheet MOSFET Layout for Leakage and Charge Trap Control
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Solution Overview
Problem
As integrated circuit devices approach the limits of scaling, there is a need for new structures to improve their performance, particularly in multi-gate MOSFETs, where charge trap and channel leakage issues hinder operation characteristics.
Innovation Solution
The integration of nanosheet stacked structures with sheet separation walls and cladding patterns, along with gate electrodes extending into concave portions of the sheet separation walls, enhances the effective channel length and reduces charge trap, thereby improving the operation characteristics of multi-gate MOSFETs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional MOSFET scaling is continued, then device size is reduced, but performance deteriorates due to charge trap and channel leakage
Solution Approach 1:
The channel region is segmented into multiple discrete nanosheets stacked vertically, creating multiple independent conduction paths. This segmentation allows each nanosheet to be independently controlled by gate electrodes, improving overall device performance while maintaining compact footprint. The sheet separation wall further segments the channel region to prevent charge trap between adjacent nanosheet stacks.
Solution Approach 2:
The invention transitions from planar 2D channel structure to 3D vertically-stacked nanosheets. Multiple nanosheets are stacked in the vertical dimension, effectively increasing the channel area without increasing the planar footprint. This dimensional transition allows continued scaling while maintaining or improving performance.
2Reliability
If multi-gate MOSFET structure is implemented, then operation characteristics are improved, but device complexity increases
Solution Approach 1:
Multiple gate electrodes are merged into a unified gate structure that wraps around each nanosheet, forming a multi-gate configuration. The sheet separation wall merges with cladding patterns to create an integrated structure that simultaneously provides mechanical support, electrical isolation, and charge trap prevention. This merging reduces the number of discrete components while maintaining complex functionality.
Solution Approach 2:
The sheet separation wall serves multiple functions: it physically separates adjacent nanosheet stacks, provides mechanical support, prevents charge trap between stacks, and defines the channel region boundaries. The cladding patterns similarly provide both structural support and electrical isolation functions, reducing the need for additional dedicated components.
3Object-generated harmful factors
If nanosheet stacked structures are used, then channel leakage is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The sheet separation wall is formed preliminarily before nanosheet stacking to pre-establish the separation structure. Cladding patterns are formed in advance on the nanosheets to provide alignment references during subsequent stacking processes. This preliminary action ensures precise alignment without requiring ultra-precise control during the critical stacking step.
Solution Approach 2:
The sheet separation wall acts as an intermediary structure between adjacent nanosheet stacks, providing a physical barrier that prevents direct interaction and charge trap. The cladding patterns serve as intermediary layers between nanosheets and gate electrodes, facilitating precise alignment and reducing manufacturing complexity by providing alignment references.
Data Source
AI summary
Provided is an integrated circuit device including a base substrate layer, a sheet separation wall extending on the base substrate layer in a first horizontal direction, a pair of nanosheet stacked structures including the sheet separation wall therebetween and apart from each other in a second horizontal direction, the second horizontal direction different from the first horizontal direction, the pair of nanosheet stacked structures each including a plurality of nanosheets, a plurality of cladding patterns between a first end of each of the plurality of nanosheets included in each of the pair of nanosheet stacked structures and the sheet separation wall, and a pair of gate electrodes extending on the pair of nanosheet stacked structures in the second horizontal direction.