Semiconductor Gate Structure with Intervening Layer for Multiple-Vt Design
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Solution Overview
Problem
As semiconductor technology advances, the challenge of achieving multiple threshold voltage (Vt) designs in integrated circuits becomes complex due to reduced gate length and limited gap-filling abilities, especially when using different gate metal materials, which is exacerbated by the need for high-k gate dielectric layers in HKMG processes.
Innovation Solution
The method involves forming semiconductor structures with intervening layers of different materials and thicknesses to achieve work function metal layers of varying thicknesses and aluminum content, allowing for the formation of multiple-Vt structures suitable for high-voltage, medium-voltage, and low-voltage devices within the same HKMG process, thereby addressing the complexity of gate length reduction and gap-filling requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different gate metal materials are used to achieve multiple threshold voltage designs, then device performance is improved, but process complexity increases due to limited gap-filling abilities and reduced gate length
Solution Approach 1:
The patent applies local quality by forming different work function metal layers (first, second, and third work function metal layers) with different materials and thicknesses in different regions of the semiconductor structure. This allows each region to have tailored electrical characteristics (different threshold voltages) while using a unified high-k gate dielectric layer and gap-filling metal layer, thus improving device performance without proportionally increasing process complexity
Solution Approach 2:
The patent employs composite materials by combining high-k gate dielectric layers with multiple work function metal layers of different materials (such as tungsten, molybdenum, titanium nitride, tantalum nitride) and by integrating these with gap-filling metal layers. This composite structure enables multiple threshold voltage designs within a single process flow, resolving the contradiction between device performance and process complexity
2Productivity
If gate length is reduced to improve production efficiency, then productivity increases, but manufacturing precision deteriorates due to limited gap-filling abilities
Solution Approach 1:
The patent applies parameter changes by systematically varying the thicknesses of different work function metal layers (first work function metal layer thinner than second, which is thinner than third) and using materials with different deposition characteristics. This enables precise control of gap-filling behavior at reduced gate lengths while maintaining high productivity, as the varying layer parameters allow optimization of both filling capability and manufacturing efficiency
3Reliability
If high-k gate dielectric layer is used to reduce gate leakage, then device performance is improved, but device complexity increases in HKMG processes
Solution Approach 1:
The patent applies universality by designing a unified high-k gate dielectric layer structure that serves multiple functions: it provides effective gate leakage control, supports multiple work function metal layers with different materials, and works with the gap-filling metal layer structure. This multi-functional approach improves gate leakage control while avoiding proportional increases in process complexity, as the same high-k dielectric framework accommodates multiple threshold voltage requirements
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 formation of semiconductor structures that meet multiple-Vt requirements while maintaining competitive gap-filling abilities, ensuring effective performance across different voltage devices by controlling aluminum diffusion and layer thicknesses, thus supporting advanced semiconductor manufacturing.
Implementation Method 1
controlling aluminum diffusion
Data Source
AI summary
A semiconductor structure includes a first metal gate structure and a second metal gate structure. The first metal gate structure includes a first high-k gate dielectric layer, a first work function metal layer over the first high-k gate dielectric layer, and a first intervening layer between the first high-k gate dielectric layer and the first work function metal layer. The second metal gate structure includes a second high-k gate dielectric layer and a second work function metal layer over the second high-k gate dielectric layer. The first work function metal layer and the second work function metal layer include a same material. A thickness of the first work function metal layer is less than a thickness of the second work function metal layer.