FinFET SDB Trench Layout for Minimal Fin Length Patterning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The integration of single diffusion break (SDB) structure and metal gate fabrication in FinFET fabrication faces challenges due to window limitations in the lithography process, hindering the effective formation of fin-shaped structures.
Innovation Solution
A method involving the formation of first and second SDB trenches to divide fin-shaped structures into three portions, followed by a fin-cut process to remove specific portions, allowing for improved photolithography focus and alignment, thereby expanding the lithography window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography process is used for FinFET fabrication, then standard manufacturing process can be followed, but lithography window limitation prevents effective formation of fin-shaped structures
Solution Approach 1:
The patent divides the fin-shaped structure into multiple segments by forming SDB trenches that partition the continuous fin structure into discrete portions. This segmentation allows each portion to be independently patterned and processed, overcoming the lithography window limitation by breaking down the complex single-step patterning into multiple simpler steps with relaxed alignment requirements.
Solution Approach 2:
The patent performs preliminary actions by forming the SDB trenches and dividing the fin structure before completing the gate patterning process. This preliminary division creates a more favorable structure for subsequent lithography steps, allowing the gate to be formed with improved alignment and focus since the underlying fin structure is already segmented into manageable portions.
2Reliability
If SDB structure is integrated with metal gate fabrication, then transistor performance can be improved, but lithography window limitation hinders the process
Solution Approach 1:
The SDB structure segments the fin into multiple portions that can be independently aligned with the gate. This segmentation relaxes the overall alignment precision requirement because each gate portion only needs to align with its corresponding fin segment rather than the entire continuous fin structure, thereby enabling successful integration of SDB with metal gate fabrication.
Solution Approach 2:
The patent applies local quality by creating different structural characteristics in different regions of the fin structure. The SDB trenches introduce localized variations in the fin structure, creating distinct regions with different electrical properties. This allows optimized gate alignment and contact formation in each local region, improving overall transistor performance while managing lithography constraints.
3Length of moving object
If fin length is reduced to minimal length, then transistor scaling is achieved, but photolithography focus and alignment become more difficult
Solution Approach 1:
The patent uses SDB trenches to segment the minimal-length fin into even smaller discrete portions. This further segmentation creates well-defined boundaries and reference features that improve photolithography focus and alignment for each individual portion, making it easier to precisely pattern gates and contacts on minimal-length fins despite the reduced overall dimension.
Solution Approach 2:
The patent introduces an additional dimensional feature by forming SDB trenches that extend vertically through the fin structure. This vertical dimensionality change creates distinct layers and interfaces that provide better focal planes for photolithography, improving focus precision when working with minimal-length fins where horizontal dimensions are severely constrained.
Data Source
AI summary
A method for fabricating minimal fin length includes the steps of first forming a fin-shaped structure extending along a first direction on a substrate, forming a first single-diffusion break (SDB) trench and a second SDB trench extending along a second direction to divide the fin-shaped structure into a first portion, a second portion, and a third portion, and then performing a fin-cut process to remove the first portion and the third portion.