FinFET Single Diffusion Break Structure for Channel Control
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Solution Overview
Problem
Current FinFET fabrication methods face challenges in integrating single diffusion break (SDB) structures and metal gate fabrication, which affect the control of the channel region and current between the source and drain in three-dimensional transistor technology.
Innovation Solution
A method involving forming a fin-shaped structure on a substrate, creating shallow trench isolation, forming a gate layer, removing parts to form a trench, and depositing a dielectric layer to create a single diffusion break structure, followed by metal gate formation to enhance control over the channel region and current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shallow trench isolation is formed around the fin-shaped structure and insulating material is deposited to form SDB structure, then the channel region control is improved, but the integration with metal gate fabrication remains problematic and complex
Solution Approach 1:
The patent divides the fin-shaped structure into multiple segments by forming trenches between adjacent fins. The SDB structure is formed in these trenches, creating distinct separation zones. This segmentation allows independent control of each fin segment while simplifying the overall integration process with metal gate fabrication by providing clear spatial boundaries.
Solution Approach 2:
The SDB structure acts as an intermediary element between the fin-shaped structure and the metal gate. By forming the SDB structure in trenches within the fin, it mediates the interaction between the channel region and the gate, improving control while providing a standardized interface that simplifies metal gate fabrication integration.
2Productivity
If the fin-shaped structure is scaled down to increase device density, then the overlapping area between gate and fin is reduced, but the control over channel region and current increases due to three-dimensional structure
Solution Approach 1:
The patent transitions from planar MOS transistor structure to three-dimensional FinFET structure by forming vertical fins. This dimensional change increases the effective channel width while maintaining a small footprint, thereby increasing device density. The vertical fin structure provides better electrostatic control over the channel region despite the scaled-down dimensions.
Solution Approach 2:
The SDB structure is formed locally within specific trenches of the fin-shaped structure, creating regions with different electrical properties. This local modification allows enhanced control over specific channel regions while maintaining the overall three-dimensional structure that provides high device density.
3Productivity
If the gate length is reduced to increase transistor density, then the current between source and drain decreases, but the three-dimensional structure compensates by increasing the effective channel length
Solution Approach 1:
By forming vertical fins, the patent increases the effective channel width (W) while maintaining a short gate length (L). The effective channel area becomes W_effective = W_fin × H_fin, where H_fin is the fin height. This allows high transistor density (small L) while maintaining sufficient current through the increased effective channel area.
Solution Approach 2:
The patent changes the geometric parameters of the channel by forming three-dimensional fins with specific height and width ratios. This parameter change increases the effective channel area without increasing the physical footprint, thereby maintaining current levels despite reduced gate length for higher density.
Data Source
AI summary
A semiconductor device includes: a fin-shaped structure on a substrate; a single diffusion break (SDB) structure in the fin-shaped structure to divide the fin-shaped structure into a first portion and a second portion; a gate structure on the first portion; and a contact etch stop layer (CESL) adjacent to the gate structure and extending to cover the SDB structure.