Segmented Metal Gate Structure to Reduce Stress and Diffusion
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Solution Overview
Problem
Existing semiconductor devices have suboptimal gate structures that require further improvements to enhance performance and stability.
Innovation Solution
A multi-layer gate structure for transistors comprising a first metal layer, a refractory metal layer, and a second metal layer, with the layers being disconnected to reduce stress and alleviate piezoelectric effects, and a passivation layer surrounding the gate structure to prevent diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous gate structure is used, then manufacturing simplicity is maintained, but stress accumulation and metal diffusion occur leading to device instability
Solution Approach 1:
The gate structure is divided into multiple disconnected metal layers (first metal layer, refractory metal layer, second metal layer) instead of using a continuous gate structure. This segmentation prevents stress accumulation and metal diffusion while maintaining manufacturing feasibility through layer-by-layer deposition processes
2Stress or pressure
If metal layers are made thin to reduce stress, then stress on underlying layers is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The gate structure employs a composite multi-layer design combining different metal materials (first metal layer, refractory metal layer, second metal layer) with distinct properties. This composite structure distributes and reduces stress on underlying layers while the standard semiconductor manufacturing processes ensure adequate thickness control for each layer
3Ease of manufacture
If a simple single-layer gate structure is used, then manufacturing is easier, but metal diffusion and electrical performance deteriorate
Solution Approach 1:
The refractory metal layer serves as an intermediary barrier layer between the first metal layer and second metal layer. This intermediate refractory layer prevents metal diffusion while maintaining the multi-layer structure's electrical performance, and the overall fabrication process remains compatible with standard semiconductor manufacturing techniques
Data Source
AI summary
A transistor device includes a substrate and a gate structure. The gate structure is disposed on the substrate. The gate structure includes a first metal layer and a refractory metal layer disposed on the first metal layer, wherein the first metal layer is disconnected and the refractory metal layer is disconnected.