Dual-Work-Function NMOS Gate Structure for Threshold Voltage Tuning

Solution Overview

Problem

Existing methods for tuning threshold voltage (VT) in CMOS devices, particularly in nanowire or nanoribbon architectures, are inadequate for precise control due to complex processing requirements and limited ability to finely tune VT between different NMOS and PMOS devices, especially in tight geometries where precise electrostatic gate control is desired.

Innovation Solution

The implementation of a dual layer gate electrode system with a first conductive layer adjacent to the gate dielectric and a second conductive layer with a different work function, combined with adjustable placement of the gate endcap wall relative to the nanowire channel sidewall, allows for fine-tuning of NMOS threshold voltage by controlling the deposition of work function materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a single gate dielectric layer is used in NMOS transistors, then the device structure is simple and manufacturing is easier, but the threshold voltage cannot be finely tuned

Engineering Contradiction:

Improvethreshold voltage tuning precisionVSAvoidgate electrode structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The gate electrode is divided into two separate conductive layers with different work functions. The first conductive layer has a first work function and the second conductive layer has a second work function different from the first. This segmentation allows independent control of each layer's contribution to the overall threshold voltage, enabling fine-tuning that would be impossible with a single gate dielectric layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The gate electrode employs a composite structure combining two different conductive materials with distinct work functions. This composite approach allows the threshold voltage to be adjusted by varying the thickness ratio or spatial arrangement of the two materials, providing a degree of control precision unattainable with homogeneous gate structures.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If the gate electrode structure is simplified for easier manufacture, then production complexity decreases, but electrostatic gate control and power consumption performance deteriorate

Engineering Contradiction:

Improvegate electrode fabrication easeVSAvoidelectrostatic gate control

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The gate electrode is divided into two separate conductive layers with different work functions. The first conductive layer has a first work function and the second conductive layer has a second work function different from the first. This segmentation allows independent control of each layer's contribution to the overall threshold voltage, enabling fine-tuning that would be impossible with a single gate dielectric layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention adjusts the work function parameter of the gate electrode by combining two conductive materials with different work functions. By changing the thickness ratio or spatial distribution of these layers, the effective work function can be precisely tuned to achieve desired threshold voltage values, thereby optimizing electrostatic gate control and power consumption without compromising manufacturability.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If threshold voltage tuning range is expanded for different applications, then device adaptability increases, but control precision may be compromised

Engineering Contradiction:

Improvevoltage setting rangeVSAvoidthreshold voltage control precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The invention adjusts the work function parameter of the gate electrode by combining two conductive materials with different work functions. By changing the thickness ratio or spatial distribution of these layers, the effective work function can be precisely tuned to achieve desired threshold voltage values, thereby optimizing electrostatic gate control and power consumption without compromising manufacturability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The gate electrode structure incorporates adjustable parameters including the thickness of each conductive layer and their relative positioning. This dynamic configurability allows the threshold voltage to be tuned across a wide range while maintaining precise control, as the two-layer structure can be optimized for different application requirements without sacrificing manufacturing precision.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12604494B2Gate end cap and boundary placement in transistor structures for N-metal oxide semiconductor (N-MOS) performance tuning

Publication Date: 2026.04.14 INTEL CORP

AI summary

A transistor structure includes a channel region including first sidewall. A gate electrode includes a first layer having a first portion adjacent to the first sidewall and a second portion adjacent to a gate electrode boundary sidewall. The gate electrode includes a second layer between the first and second portions of the first layer. The first layer has a first composition associated with a first work function material, and has a first lateral thickness from the first sidewall. The second layer has a second composition associated with a second work function material. Depending one a second lateral thickness of the second layer, the second layer may modulate a threshold voltage (VT) of the transistor structure by more or less. In some embodiments, a ratio of the second lateral thickness to the first lateral thickness is less than three.