SiGe Fin Structure Ge Redistribution for Low-Leakage FinFETs

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Solution Overview

Problem

The challenge in semiconductor manufacturing lies in achieving higher carrier mobility and lower threshold voltage while minimizing current leakage in Fin FETs, particularly due to the high Ge concentration in the channel region leading to sub-threshold current leakage.

Innovation Solution

A non-uniform Ge concentration is achieved in the SiGe fin structure by redistributing Ge through melting laser annealing, with higher concentration at the surface and lower concentration at the center, enhancing carrier mobility and suppressing current leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If high Ge concentration is used in the channel region to enhance carrier mobility, then device performance is improved, but sub-threshold current leakage increases

Engineering Contradiction:

Improvecarrier mobilityVSAvoidsub-threshold current leakage

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by creating a non-uniform Ge concentration distribution within the channel region. The Ge concentration is higher near the surface (enhancing carrier mobility) and lower toward the center (reducing sub-threshold leakage). This spatial variation in material composition allows simultaneous optimization of both carrier mobility and leakage suppression in different regions of the same channel structure.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If uniform Ge concentration is used in the fin structure, then manufacturing is simplified, but device performance is suboptimal due to inability to simultaneously achieve high carrier mobility and low leakage

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoiddevice performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent employs parameter changes by varying the Ge concentration parameter throughout the channel region. Instead of maintaining a constant Ge concentration, the composition is dynamically adjusted spatially - higher Ge content near the surface for mobility enhancement and lower Ge content toward the center for leakage reduction. This parameter variation enables superior device performance while remaining compatible with existing epitaxial growth manufacturing processes.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach improves on-state current and reduces threshold voltage by optimizing Ge distribution, thereby enhancing device performance.

Implementation Method 1

melting laser annealing

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

melting laser annealing

Methodology Applied

Scientific EffectLaser heating: Laser

Data Source

PatentUS12490454B2Method of manufacturing semiconductor devices and semiconductor devices

Publication Date: 2025.12.02 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

In a method of manufacturing a semiconductor device including a Fin FET, a fin structure, which has an upper fin structure made of SiGe and a bottom fin structure made of a different material than the upper fin structure, is formed, a cover layer is formed over the fin structure, a thermal operation is performed on the fin structure covered by the cover layer, and a source/drain epitaxial layer is formed in a source/drain region of the upper fin structure. The thermal operation changes a germanium distribution in the upper fin structure.