Semiconductor Gate Electrode With Low-K Dielectric Cap Layer
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Solution Overview
Problem
As semiconductor integration density increases, existing technologies face challenges such as short channel effects (SCE) and drain induced barrier lowering (DIBL) in bulk devices, which also make it difficult to achieve a desired sub-threshold slope (SS).
Innovation Solution
A semiconductor device is designed with a substrate, recessed epitaxial channel layers, a high-K gate dielectric layer, a gate electrode comprising an inner metal gate and an outer metal barrier, and a dielectric cap layer with a lower dielectric constant, along with shallow trench isolation and silicide regions, to minimize SCEs and improve DIBL characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional bulk device configurations are used to increase integration density, then more transistors can be integrated, but short channel effects and drain induced barrier lowering worsen
Solution Approach 1:
The gate electrode is segmented into a first gate electrode portion and a second gate electrode portion positioned at different heights, creating a multi-level gate structure that segments the electric field distribution and improves control over the channel region
Solution Approach 2:
The invention transitions from a planar gate structure to a three-dimensional multi-level gate structure by positioning gate electrode portions at different vertical heights, adding a vertical dimension to the gate configuration to enhance control without increasing lateral footprint
2Productivity
If smaller transistors are integrated in bulk devices, then integration density increases, but achieving desired sub-threshold slope becomes difficult
Solution Approach 1:
The gate electrode is segmented into a first gate electrode portion and a second gate electrode portion positioned at different heights, creating a multi-level gate structure that segments the electric field distribution and improves control over the channel region
Solution Approach 2:
Different regions of the gate structure have different heights and configurations - the first gate electrode portion extends to a first height while the second gate electrode portion extends to a second height, allowing localized optimization of electric field control in different vertical regions
Data Source
AI summary
A semiconductor device may include a substrate, source and drain regions in the substrate, a recessed epitaxial channel layer in the substrate between the source and drain regions, and a high-K gate dielectric layer overlying the recessed epitaxial channel layer. The semiconductor device may further include a gate electrode overlying the high-K gate dielectric layer, a dielectric cap layer in contact with top and sidewall portions of the gate electrode, the dielectric cap layer having a lower dielectric constant than the high-K gate dielectric layer, and source and drain contacts coupled to the source and drain regions.