High-Breakdown Capacitor Structure for Leakage-Isolated Mixed-Signal ICs
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Solution Overview
Problem
Existing semiconductor devices face challenges in increasing high-voltage isolation while minimizing leakage current, particularly in mixed analog-digital circuit regions, as thick oxide interlayer insulating films are limited and the use of low bandgap materials introduces undesired leakage.
Innovation Solution
The semiconductor device incorporates a structure with a thick inter-metal dielectric layer, low bandgap dielectric layers made of silicon nitride, and hard mask layers of metal nitride, featuring etch grooves and spacers to isolate the low bandgap dielectric layers to specific regions, preventing leakage in mixed-signal circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low bandgap materials are incorporated into high-voltage isolation capacitors to increase high-voltage isolation, then high-voltage isolation capability is improved, but undesired leakage current is induced in mixed analog-digital circuit regions
Solution Approach 1:
The patent applies low bandgap dielectric layers (silicon nitride) selectively only in high-voltage isolation capacitor regions, while using conventional high bandgap dielectric layers in mixed analog-digital circuit regions. This local differentiation allows the low bandgap material to enhance breakdown voltage where needed without introducing leakage current in sensitive circuit areas.
Solution Approach 2:
The dielectric structure is segmented into multiple layers with different bandgap characteristics. The low bandgap dielectric layer is positioned specifically between the bottom electrode and thick inter-metal dielectric layer in isolation capacitor regions, while hard mask layers provide additional isolation. This segmentation enables targeted application of low bandgap materials to achieve high-voltage isolation without compromising circuit regions.
2Reliability
If the thickness of thick oxide interlayer insulating film is increased to achieve high voltage isolation, then high-voltage isolation is improved, but it becomes hard to further increase isolation performance
Solution Approach 1:
The patent employs a composite dielectric structure combining thick inter-metal dielectric layers (oxide-based) with low bandgap dielectric layers (silicon nitride) and hard mask layers. This composite approach leverages the high breakdown strength of thick oxide layers while using low bandgap materials to further enhance isolation performance without simply increasing oxide thickness, thus avoiding excessive device complexity.
Solution Approach 2:
The patent changes the bandgap parameter of dielectric materials from high bandgap (conventional oxide) to low bandgap (silicon nitride) in specific regions. This parameter change enables enhanced voltage isolation capability by utilizing materials with different electrical properties, allowing further improvement in high-voltage isolation beyond what can be achieved by thickness increase alone.
3Reliability
If low bandgap dielectric layers are applied in mixed analog-digital circuit regions to increase high-voltage isolation, then isolation capability is improved, but leakage current increases in the circuit region
Solution Approach 1:
The patent strictly limits the application of low bandgap dielectric layers to high-voltage isolation capacitor regions only, using hard mask layers to define precise boundaries. Mixed analog-digital circuit regions are isolated using conventional high bandgap dielectric layers, ensuring that low bandgap materials do not contact or influence circuit operations, thereby preventing leakage current in sensitive circuit areas while maintaining enhanced isolation in capacitor regions.
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 configuration enhances high-voltage isolation capabilities while minimizing leakage current, optimizing manufacturing processes, and reducing costs by targeted application of low bandgap materials only in high-voltage isolation regions.
Implementation Method 1
low bandgap dielectric layers made of silicon nitride, and hard mask layers of metal nitride
Data Source
AI summary
A semiconductor device includes a bottom metal line and a bottom electrode disposed on a substrate, a thick inter-metal dielectric layer disposed on the bottom metal line and the bottom electrode, a first via disposed on the bottom metal line disposed in the thick inter-metal dielectric layer, a second via disposed on the first via, a top metal line disposed on the second via and overlapping the bottom metal line, a low bandgap dielectric layer disposed on the thick inter-metal dielectric layer, a hard mask layer disposed on the low bandgap dielectric layer, a top electrode disposed on the hard mask layer and overlapping the bottom electrode, and a passivation layer disposed on the top metal line and the top electrode.