Metal Gate Leakage Reduction via Oxide Barrier Layer
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Solution Overview
Problem
Conventional metal gate electrodes in semiconductor devices often experience gate leakage due to inter-metallic compound formation, leading to device instability and failure.
Innovation Solution
A method for fabricating a metal gate electrode that involves forming a metal oxide layer between the work-function metal layer and the metal barrier layer to prevent Al and Ti diffusion, thereby eliminating inter-metallic compound formation and reducing gate leakage, using an oxidation process to oxidize the first metal layer deposited over the gate insulator, followed by deposition and planarization of subsequent metal layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a metal gate electrode is formed using conventional processes with a work-function metal layer (Al/Ti) and metal barrier layer, then the gate electrode can be fabricated with reduced feature sizes, but inter-metallic compounds form between the metal layers creating gate leakage paths
Solution Approach 1:
A metal oxide layer is introduced as an intermediary barrier between the work-function metal layer (Al/Ti) and the metal barrier layer. This oxide layer prevents direct contact and diffusion between the metal layers, thereby eliminating inter-metallic compound formation and the associated gate leakage paths while maintaining the functional integrity of the gate electrode structure
Solution Approach 2:
The gate electrode structure is segmented into distinct layers with the metal oxide layer positioned between the work-function metal layer and the metal barrier layer. This segmentation creates physical separation that prevents harmful interactions between adjacent metal layers while preserving the individual functions of each layer
2Productivity
If the gate oxide thickness is reduced to maintain performance with decreased gate length, then transistor performance is maintained, but gate leakage increases
Solution Approach 1:
The gate structure employs a composite material system consisting of multiple layers including the gate dielectric layer, work-function metal layer, metal oxide layer, and metal barrier layer. This composite structure allows for optimized thickness of each layer to achieve both high performance and low leakage by combining materials with complementary properties
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 approach results in a metal gate electrode with a significantly reduced leakage path, enhancing device stability and reliability by preventing inter-metallic compound formation and maintaining performance.
Implementation Method 1
using an oxidation process to oxidize the first metal layer deposited over the gate insulator
Data Source
AI summary
A semiconductor device structure, for improving the metal gate leakage within the semiconductor device. A structure for a metal gate electrode for a n-type Field Effect Transistor includes a capping layer; a first metal layer comprising Ti and Al over the capping layer; a metal oxide layer over the first metal layer; a barrier layer over the metal oxide layer; and a second metal layer over the barrier layer.