Multi-Gate HKMG Barrier Layers for Al Diffusion Control
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Solution Overview
Problem
As semiconductor technology advances, the challenge of forming high-k metal gate (HKMG) structures for multiple-threshold voltage (Vt) designs becomes complex due to the need for precise control of gate dielectric layers and barrier materials, especially as gate lengths scale down, requiring improved diffusion barrier capabilities to maintain performance and efficiency.
Innovation Solution
The method involves forming semiconductor structures using an HKMG process with in-situ and ex-situ nitridation of barrier layers with varying nitrogen concentrations to enhance the metal barrier abilities, specifically using tungsten-based barrier layers with controlled nitrogen content to manage aluminum diffusion and meet multiple-Vt requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Al diffusion barrier layers are used to prevent Al diffusion into high-k gate dielectric layers, then device reliability is improved, but manufacturing complexity increases due to the need for multiple barrier layer materials and processes
Solution Approach 1:
The patent modifies the chemical composition parameters of the barrier layer by incorporating nitrogen at controlled concentrations (5-50 atomic percent). This parameter change transforms the barrier layer from a simple physical barrier to a chemically optimized structure that provides superior Al diffusion blocking while maintaining processability. The nitrogen concentration is specifically controlled to achieve the desired diffusion barrier performance without excessive complexity.
Solution Approach 2:
The invention creates a composite barrier layer structure combining aluminum oxide with nitrogen-containing compounds. This composite approach leverages the diffusion-blocking properties of Al2O3 while adding nitrogen to enhance the barrier effectiveness against Al diffusion. The composite structure provides improved reliability through synergistic material properties rather than relying on a single complex material system.
2Adaptability or versatility
If multiple gate metal materials are used to achieve multiple-Vt designs, then device functionality is improved, but ease of manufacture deteriorates due to limited gap-filling abilities
Solution Approach 1:
The patent applies local quality by creating barrier layers with spatially varying nitrogen concentrations. Different regions of the barrier layer have different nitrogen content (5-50 atomic percent), which allows optimization of both diffusion blocking and gap-filling properties in different locations. This local variation in composition enables the single barrier layer structure to provide multiple-Vt design capabilities while maintaining manufacturability.
Solution Approach 2:
The invention changes the compositional parameters of the barrier layer by introducing nitrogen at controlled concentrations to modify both the diffusion barrier properties and the gap-filling characteristics. This parameter modification allows the barrier layer to serve dual purposes: preventing Al diffusion while also providing adequate gap-filling ability for multiple-Vt device fabrication, thereby improving ease of manufacture.
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 effectively mitigates aluminum diffusion into high-k gate dielectric layers, allowing for thinner barrier layers that maintain competitive gap-filling abilities while supporting multiple-Vt designs, suitable for both high-voltage and low-voltage devices, thereby improving semiconductor performance and efficiency.
Implementation Method 1
forming a barrier layer over the high-k gate dielectric layer to block Al diffusion
Implementation Method 2
in-situ and/or ex-situ nitridation to enhance nitrogen concentration in barrier layers
Data Source
AI summary
A semiconductor structure includes a first multi-gate transistor and a second multi-gate transistor. The first multi-gate transistor includes a first Al-containing high-k dielectric layer having a first Al concentration, and a W-and-N-containing barrier layer. The second multi-gate transistor includes a second Al-containing high-k dielectric layer having a second Al concentration. The first Al concentration is less than the second Al concentration.