Single Diffusion Break Fin Layout for Precise Gate Alignment

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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 precise alignment and removal 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, and enabling the formation of minimal-length fin structures with aligned gate structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional FinFET fabrication with SDB structure is used, then transistor scaling and channel control are achieved, but photolithography window limitation prevents precise alignment and fin removal

Engineering Contradiction:

Improvephotolithography alignment precisionVSAvoidfabrication process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The fin-shaped structure is divided into three distinct portions by forming first and second SDB trenches that extend in a direction intersecting the fin extension direction. This segmentation enables selective removal of outer portions while preserving the inner portion for gate formation, thereby achieving precise alignment control that overcomes photolithography window limitations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The SDB trenches are formed beforehand to define precise locations for subsequent fin removal. By pre-establishing these trenches along predetermined lines, the method enables accurate alignment of the gate structure with the remaining fin portion, solving the alignment precision problem without increasing overall process complexity.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If photolithography window is enlarged for better alignment, then fabrication precision improves, but process time and complexity increase

Engineering Contradiction:

Improvefin structure alignment precisionVSAvoidfabrication process time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

By segmenting the fin structure into three portions using intersecting SDB trenches, the method achieves precise alignment control in a single photolithography step rather than requiring multiple alignment steps, thereby maintaining manufacturing precision while reducing process time.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The SDB trenches extend in a direction intersecting the fin extension direction, utilizing a different dimensional approach to achieve alignment precision. This cross-directional trench formation enables accurate fin portion definition without requiring extended photolithography windows or additional alignment steps.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS12408393B2Semiconductor device with a single diffusion break structure and a gate structure having aligned sidewalls

Publication Date: 2025.09.02 UNITED MICROELECTRONICS CORP

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.