FinFET Gate Stack Barrier Layer for Aluminum Oxidation Control
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Solution Overview
Problem
Existing FinFET devices and manufacturing methods are not entirely satisfactory in all respects, particularly in terms of complexity and efficiency in scaling down semiconductor integrated circuits, which hinders further advancements in IC manufacturing.
Innovation Solution
A method for forming FinFET devices involves forming fins on a substrate, creating dummy gate strips, forming strained layers, and using a barrier layer between the N-type work function metal layer and the metal filling layer to prevent aluminum oxidation, thereby reducing threshold voltage and enhancing manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional TiN glue layer is used between the N-type work function metal layer and the metal filling layer, then aluminum oxidation is prevented, but the manufacturing process complexity increases and the metal-gate fill window is reduced
Solution Approach 1:
The patent removes the conventional TiN glue layer from the gate stack structure, extracting this intermediate layer that was previously used to prevent aluminum oxidation. Instead, the invention directly contacts the N-type work function metal layer with the metal filling layer, relying on the inherent properties of these materials to prevent oxidation without requiring an additional TiN barrier layer.
Solution Approach 2:
The N-type work function metal layer serves multiple functions: it provides the work function adjustment for the gate electrode and simultaneously acts as a barrier to prevent aluminum oxidation from the metal filling layer. This multi-functionality eliminates the need for a separate TiN glue layer, reducing process complexity while maintaining reliability.
2Productivity
If existing FinFET manufacturing methods are used, then device functionality is achieved, but manufacturing efficiency is limited and threshold voltage control is suboptimal
Solution Approach 1:
The patent modifies the gate stack composition by using an N-type work function metal layer with specific material properties (such as tungsten or molybdenum nitride) that provide both work function adjustment and oxidation barrier functionality. This parameter change in material selection and layer configuration improves both manufacturing efficiency and threshold voltage control simultaneously.
Solution Approach 2:
The invention employs composite material structures in the gate stack, combining the N-type work function metal layer with the metal filling layer in a way that creates synergistic effects. The composite structure provides both the electrical properties needed for threshold voltage control and the chemical stability to prevent oxidation, improving manufacturing outcomes without additional process steps.
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
The method improves the efficiency of FinFET device manufacturing by reducing threshold voltage and eliminating the need for a conventional TiN glue layer, thereby enlarging the metal-gate fill window and enhancing operational performance.
Implementation Method 1
a barrier layer between the N-type work function metal layer and the metal filling layer to prevent aluminum oxidation
Data Source
AI summary
Semiconductor devices, FinFET devices and methods of forming the same are disclosed. One of the semiconductor devices includes a substrate and a gate strip disposed over the substrate. The gate strip includes a high-k layer disposed over the substrate, an N-type work function metal layer disposed over the high-k layer, and a barrier layer disposed over the N-type work function metal layer. The barrier layer includes at least one first film containing TiAlN, TaAlN or AlN.