Gate Electrode AlW Tuning Layers for Threshold Voltage Control

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Solution Overview

Problem

The semiconductor industry faces challenges in tuning work function values of gate electrodes in semiconductor devices, which affects the integration density and performance of electronic components, particularly in achieving lower threshold voltages and higher speed.

Innovation Solution

The method involves implanting dopants like lanthanum, aluminum, or magnesium in p-type work function metal layers and exposing n-type work function metal layers to transition metal chlorides to alter their composition and form suitable work function layers, thereby tuning the work function values and increasing the process window for gate electrode filling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional gate electrode fabrication is used, then manufacturing simplicity is maintained, but work function tuning capability and device performance are insufficient

Engineering Contradiction:

Improvedevice performanceVSAvoidgate electrode structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The gate electrode is divided into multiple functional layers including work function metal layers (p-type and n-type), tuning layers, and fill material layers. Each layer serves a specific function in work function adjustment and device performance optimization, allowing independent control of electrical characteristics.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the gate electrode are assigned different material compositions and properties. P-type work function metal layers are used in specific regions to achieve desired work function values, and doping is applied locally to adjust electrical characteristics in different areas of the gate electrode.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If work function metal layers are added to tune work function values, then threshold voltage control is improved, but manufacturing process complexity increases

Engineering Contradiction:

Improvethreshold voltage controlVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The work function of the gate electrode is tuned by changing material parameters including composition ratios (e.g., TiAl with controlled Al content), doping concentrations (e.g., lanthanum, aluminum, or magnesium dopants in p-type layers), and layer thicknesses. These parameter adjustments enable precise threshold voltage control.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The gate electrode employs composite material structures combining multiple metal layers with different properties. P-type work function metal layers are combined with n-type work function metal layers, and transition metal chlorides are used as tuning layers, creating a composite structure that achieves desired electrical characteristics.

Inventive Principle:

Principle #40Composite materials

3Productivity

If integration density is increased by reducing feature size, then component count per area is improved, but manufacturing precision and control over work function become more difficult

Engineering Contradiction:

Improveintegration densityVSAvoidwork function control

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The gate electrode is segmented into multiple functional layers including work function metal layers (p-type and n-type), tuning layers, and fill material layers. Each layer serves a specific function in work function adjustment and device performance optimization, allowing independent control of electrical characteristics.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

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 the manufacturing of semiconductor devices with lower threshold voltages, higher speed, and improved performance by optimizing work function values, enhancing integration density and flexibility in subsequent layer deposition.

Implementation Method 1

implanting dopants like lanthanum, aluminum, or magnesium in p-type work function metal layers

Methodology Applied

Scientific EffectIon implantation: Ion Implantation

Implementation Method 2

exposing n-type work function metal layers to transition metal chlorides to alter their composition and form suitable work function layers

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Data Source

PatentUS12166095B2Semiconductor device and method

Publication Date: 2024.12.10 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Methods for tuning effective work functions of gate electrodes in semiconductor devices and semiconductor devices formed by the same are disclosed. In an embodiment, a semiconductor device includes a channel region over a semiconductor substrate; a gate dielectric layer over the channel region; and a gate electrode over the gate dielectric layer, the gate electrode including a first work function metal layer over the gate dielectric layer, the first work function metal layer including aluminum (Al); a first work function tuning layer over the first work function metal layer, the first work function tuning layer including aluminum tungsten (AlW); and a fill material over the first work function tuning layer.