Tri-Layer FinFET Gate Structure for Fluorine Diffusion Blocking
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Solution Overview
Problem
The semiconductor industry faces challenges in manufacturing fin field-effect transistors (FinFETs) due to issues in achieving precise patterning and integration of high-k gate dielectric materials, which affect device performance and reliability.
Innovation Solution
A method for manufacturing FinFETs involving the formation of semiconductor fins, insulating material deposition, dummy gate structure creation, and subsequent replacement with a gate structure comprising a gate dielectric layer, work function layer, barrier layer, and metal layer, where the barrier layer includes silicon or aluminum to trap fluorine impurities and prevent threshold voltage shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gate replacement technologies are used to manufacture metal gate structure, then device performance is improved, but manufacturing complexity increases
Solution Approach 1:
The gate structure is divided into multiple functional layers including high-k gate dielectric layer, work function layer, and barrier layer. Each layer serves a specific function: the high-k dielectric provides gate control, the work function layer sets threshold voltage, and the barrier layer prevents fluorine diffusion. This segmentation allows optimization of each layer independently while maintaining overall device performance.
Solution Approach 2:
The barrier layer is formed between the work function layer and metal layer before potential fluorine contamination can occur. This preliminary protective action prevents fluorine diffusion into the work function layer, which would otherwise cause threshold voltage shifts and device failure. The barrier layer is prepared in advance to mitigate future contamination risks.
2Reliability
If high-k gate dielectric materials are used, then device performance is improved, but integration precision becomes more difficult to achieve
Solution Approach 1:
Different regions of the gate structure have different material compositions and properties optimized for their specific functions. The high-k gate dielectric layer provides superior gate control in the channel region, while the barrier layer provides fluorine blocking at the metal-dielectric interface. Each layer's properties are locally optimized to address specific interface challenges.
Solution Approach 2:
The gate structure employs a composite multi-layer architecture combining high-k dielectric materials (such as HfO2, ZrO2, or their silicates) with metal layers (such as tungsten, cobalt, or copper) and intermediate barrier layers. This composite structure leverages the advantages of each material: high-k dielectric for gate control, metal for conductivity, and barrier layer for contamination prevention, achieving overall superior device performance despite manufacturing challenges.
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 control over FinFET structure and performance, enhancing device reliability by preventing fluorine impurity diffusion and maintaining threshold voltage stability.
Implementation Method 1
the barrier layer includes silicon or aluminum to trap fluorine impurities and prevent threshold voltage shifts
Data Source
AI summary
A gate structure includes a gate dielectric layer, a work function layer, a metal layer, and a barrier layer. The work function layer is surrounded by the gate dielectric layer. The metal layer is disposed over the work function layer. The barrier layer is surrounded by the work function layer and surrounds the metal layer. The barrier layer includes fluorine and silicon, or fluorine and aluminum. The barrier layer is a tri-layered structure.