Granular Barrier Structure for Semiconductor Gate Metal Diffusion Control
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Solution Overview
Problem
As semiconductor technology nodes shrink, achieving multiple threshold voltages (Vt) in integrated circuits becomes challenging due to limitations in current gate metal materials and thin work function metals, particularly in advanced nodes where gate length scales down, leading to difficulties in device design and performance.
Innovation Solution
A semiconductor structure is developed with a barrier structure comprising a plurality of granules between the work function metal layer and the gate dielectric layer, which acts as a metal barrier to modulate threshold voltage, offering superior metal barrier ability even with an ultra-thin thickness, suitable for small gate lengths and advanced technology nodes, and facilitating scaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin barrier layer is used to prevent metal diffusion in advanced nodes, then metal barrier ability is improved, but manufacturing precision and control become more difficult
Solution Approach 1:
The barrier layer is segmented into discrete granules rather than forming a continuous thin film. This segmentation allows the barrier function to be distributed across multiple discrete elements, reducing the need for precise thickness control of a continuous layer while maintaining effective metal diffusion prevention through the granular structure.
Solution Approach 2:
The barrier granules provide localized metal diffusion protection at critical interfaces between the work function metal and gate dielectric. Rather than requiring uniform thin barrier coverage everywhere, the granular structure concentrates barrier functionality at specific locations where metal diffusion is most problematic, improving manufacturing tolerability.
2Adaptability or versatility
If work function metal layer thickness is reduced to achieve multiple Vt designs, then device design flexibility is improved, but metal diffusion control deteriorates
Solution Approach 1:
The barrier granules serve as an intermediary layer between the work function metal and gate dielectric, mediating the interaction between these two layers. This intermediary structure enables the use of thin work function metal layers for multiple Vt designs while preventing direct metal diffusion into the gate dielectric, thus resolving the contradiction between design flexibility and diffusion control.
3Productivity
If gate dielectric layer thickness is reduced to maintain performance with decreased gate length, then device performance is improved, but gate leakage increases
Solution Approach 1:
The gate structure employs a composite arrangement combining the gate dielectric layer with barrier granules and work function metal layer. This composite structure allows the gate dielectric to be thinner for improved device performance while the barrier granules provide additional protection against gate leakage by preventing metal diffusion that would otherwise degrade the dielectric's insulating 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
This solution enables the achievement of multiple Vt designs with improved metal barrier performance, reducing metal diffusion into the gate dielectric, thus enhancing device performance and scalability in advanced technology nodes while maintaining minimal impact on gap filling.
Implementation Method 1
a barrier structure comprising a plurality of barrier granules between the work function metal layer and the gate dielectric layer, the barrier granules providing the barrier structure with a metal barrier ability
Data Source
AI summary
A semiconductor device and a method for forming a semiconductor are provided. The semiconductor structure includes a gate structure. The gate structure includes a gate dielectric layer, a work function metal layer over the gate dielectric layer, and a plurality of barrier granules between the gate dielectric layer and the work function metal layer. At least two adjacent barrier granules of the plurality of barrier granules are separated from each other by a portion of the work function metal layer.