FinFET Threshold Voltage Tuning With TaN Layer Thickness Control

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Solution Overview

Problem

Existing gate replacement processes for ICs face challenges in achieving precise threshold voltage tuning, particularly at advanced technology nodes, due to issues like gap filling and shadowing effects, which affect device performance.

Innovation Solution

A method involving the use of a threshold voltage tuning layer with a material like tantalum and nitrogen, applied through ALD, to adjust the work function value based on thickness, overcoming gap fill and shadowing issues by ensuring uniform doping and consistent threshold voltages across different voltage regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If existing gate replacement processes are used, then device fabrication can proceed, but precise threshold voltage tuning cannot be achieved due to gap filling and shadowing effects

Engineering Contradiction:

Improvethreshold voltage tuning precisionVSAvoiddevice performance consistency

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent changes the material parameter from conventional metal gate materials to a threshold voltage tuning layer composed of tantalum and nitrogen. This material substitution enables continuous threshold voltage adjustment by controlling the nitrogen concentration and layer thickness, thereby achieving precise threshold voltage tuning without the gap filling and shadowing effects that plague conventional processes.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite material system consisting of tantalum and nitrogen forming a threshold voltage tuning layer. This composite structure allows for tailored electrical properties by adjusting the nitrogen content and layer composition, enabling precise control over threshold voltage while maintaining manufacturing reliability at advanced technology nodes.

Inventive Principle:

Principle #40Composite materials

2Reliability

If gate replacement processes are implemented, then device performance improves, but threshold voltage uniformity deteriorates due to shadowing effects

Engineering Contradiction:

Improvedevice performanceVSAvoidthreshold voltage uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the deposition method and material parameters to form a threshold voltage tuning layer that is inherently more uniform than conventional metal gate structures. By controlling the tantalum and nitrogen deposition parameters and layer thickness, the process achieves consistent threshold voltage across the wafer, eliminating the shadowing effects that cause uniformity problems in gate replacement processes.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If technology nodes are scaled down, then production efficiency increases, but processing complexity increases

Engineering Contradiction:

Improveproduction efficiencyVSAvoidprocessing complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent simplifies the processing at advanced technology nodes by replacing complex multi-step gate replacement processes with a more straightforward threshold voltage tuning layer formation process. By adjusting material composition and deposition parameters, the invention achieves the required device performance without the intricate processing steps needed in conventional approaches, thereby reducing processing complexity while maintaining high productivity.

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 enables precise threshold voltage tuning, improving device performance by preventing aluminum penetration and ensuring uniform doping, thus enhancing the reliability and efficiency of FinFET devices at smaller technology nodes.

Implementation Method 1

a threshold voltage tuning layer with a material like tantalum and nitrogen, applied through ALD, to adjust the work function value based on thickness

Methodology Applied

Scientific EffectWork function tuning through thickness control:

Implementation Method 2

applied through ALD, to adjust the work function value based on thickness

Methodology Applied

Scientific EffectAtomic Layer Deposition:

Data Source

PatentUS20250324729A1Threshold Voltage Tuning for Fin-Based Integrated Circuit Device

Publication Date: 2025.10.16 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Methods for tuning threshold voltages of fin-like field effect transistor (FinFET) devices are disclosed herein. An exemplary integrated circuit device includes a high voltage n-type FinFET, a high voltage p-type FinFET, a low voltage n-type FinFET, and a low voltage p-type FinFET. Threshold voltages of the high voltage n-type FinFET and the high voltage p-type FinFET are greater than threshold voltages of the low voltage n-type FinFET and the low voltage p-type FinFET, respectively. The high voltage n-type FinFET, the high voltage p-type FinFET, the low voltage n-type FinFET, and the low voltage p-type FinFET each include a threshold voltage tuning layer that includes tantalum and nitrogen. Thicknesses of the threshold voltage tuning layer of the low voltage n-type FinFET and the low voltage p-type FinFET are less than thicknesses of the threshold voltage tuning layer of the high voltage n-type FinFET and the high voltage p-type FinFET, respectively.