Nanosheet Channel Structures with Thin Silicon Work-Function Layers

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Solution Overview

Problem

The challenge in semiconductor manufacturing is achieving further down-scaling of transistors while maintaining effective gate control, as traditional aluminum-containing work function adjustment layers hinder size reduction due to their thickness requirements.

Innovation Solution

Employing a silicon-containing work function adjustment layer with a reduced thickness, which allows for the formation of nanosheet channel structures in gate-all-around transistors, enabling further down-scaling without compromising gate control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If aluminum-containing work function adjustment layers are used, then the desired work function is achieved, but the layer thickness increases hindering device down-scaling

Engineering Contradiction:

Improvedevice dimensionVSAvoidwork function adjustment layer thickness

Core Design Contradiction:

Length of moving objectVSLength of stationary object

Solution Approach 1:

The patent changes the material composition parameter of the work function adjustment layer from aluminum-containing to silicon-containing material. This parameter change enables the layer to achieve the desired work function (4.05 eV to 4.25 eV) with a reduced thickness of 5 nm to 15 nm, thereby resolving the contradiction between achieving the target work function and minimizing layer thickness for device down-scaling

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure consisting of a high-k dielectric layer (first material layer) and a silicon-containing work function adjustment layer (second material layer). The high-k dielectric layer provides gate control while the thin silicon-containing layer adjusts the work function. This composite approach allows the gate structure to achieve both effective channel control and appropriate work function with overall reduced thickness, enabling further device down-scaling

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS12414340B2Semiconductor structure including nanosheet channel structure and method for forming the same

Publication Date: 2025.09.09 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

The present disclosure provides a semiconductor structure and a method for forming the same. The semiconductor structure includes a first nanosheet channel structure and a first high-k dielectric layer surrounding the first nanosheet channel structure. In addition, the semiconductor structure includes a second nanosheet channel structure disposed above and substantially parallel to the first nanosheet channel structure, and a second high-k dielectric layer surrounding the second nanosheet channel structure. The semiconductor structure further includes a work function adjustment layer including silicon and disposed between the first high-k dielectric layer and the second high-k dielectric layer. The first high-k dielectric layer and the second high-k dielectric layer are separated by the work function adjustment layer.