FinFET SDB Isolation Structure for Threshold Voltage 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 threshold voltage in fin-shaped transistors.
Innovation Solution
A method involving the formation of a single diffusion break structure to divide fin-shaped structures into portions, followed by the creation of a metal gate and dielectric layers, which includes forming a T-shaped or T-cross-section isolation structure and spacers to enhance the semiconductor device's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single diffusion break (SDB) structure is formed to divide the fin-shaped structure, then the control over the channel region and threshold voltage is improved, but the device complexity and fabrication difficulty increase
Solution Approach 1:
The fin-shaped structure is divided into multiple portions by forming an SDB structure that creates a trench between them. This segmentation allows independent control of each fin portion, improving threshold voltage control and reducing short channel effects while maintaining manageable fabrication through staged processing
Solution Approach 2:
The SDB structure introduces localized doping regions with different concentrations in specific areas of the fin structure. This creates local variations in electrical properties that enable precise control of the channel region and threshold voltage without affecting the entire device uniformly
2Reliability
If the fin-shaped structure is divided into multiple portions with SDB structure, then the drain-induced barrier lowering effect is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The SDB trench is formed preliminarily before final gate structure fabrication. This preliminary action establishes the diffusion barrier early in the process, preventing drain-induced barrier lowering effects while allowing subsequent steps to focus on achieving the required precision with better process control
3Adaptability or versatility
If metal gate structures are formed after SDB structure, then the integration of SDB and metal gate fabrication is achieved, but the fabrication process complexity increases
Solution Approach 1:
The fabrication process is segmented into distinct stages: SDB structure formation, followed by metal gate formation. This segmentation allows each process to be optimized independently while ensuring proper integration, managing overall process complexity through structured sequencing
Data Source
AI summary
A semiconductor device includes a single diffusion break (SDB) structure dividing a fin-shaped structure into a first portion and a second portion, a first isolation structure on the SDB structure, a shallow trench isolation (STI) adjacent to the SDB structure, and a second isolation structure on the STI. Preferably, the first isolation structure further includes a cap layer on the SDB structure and a dielectric layer on the cap layer.