Isolation Capacitor Layout for High-Voltage Isolation With Low Leakage
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Solution Overview
Problem
Existing semiconductor devices face challenges in increasing high-voltage isolation while minimizing leakage current in mixed analog-digital circuit regions, as increasing the thickness of thick oxide interlayer insulating films is limited and using low bandgap materials can induce undesired leakage currents.
Innovation Solution
The semiconductor device incorporates a high-voltage isolation capacitor with low bandgap dielectric layers disposed between the inter-metal dielectric layers and top electrodes in the high-voltage isolation capacitor region, but absent in the mixed-signal integrated circuit region, to enhance isolation without inducing excessive leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the thick oxide interlayer insulating film is increased to improve high-voltage isolation, then the high-voltage isolation capability is improved, but it becomes difficult to achieve further isolation enhancement due to manufacturing limitations
Solution Approach 1:
The patent employs a composite dielectric structure combining thick oxide interlayer insulating film (e.g., SiO2) with low bandgap material layers (e.g., Si3N4, SiOCN, or SiCN). This composite approach leverages the high breakdown voltage of thick oxide while incorporating low bandgap materials that provide additional isolation enhancement without requiring excessive oxide thickness, thus resolving the manufacturing limitation.
Solution Approach 2:
The patent changes the bandgap parameter of the dielectric materials by introducing low bandgap materials with bandgaps lower than the thick oxide interlayer insulating film. This parameter change enables achieving higher voltage isolation (e.g., 5 kV or more) without simply increasing the oxide thickness beyond manufacturing capabilities.
2Reliability
If low bandgap materials are incorporated into the high-voltage isolation capacitors to increase high-voltage isolation, then the isolation capability is improved, but undesired leakage current is induced in the mixed analog-digital circuit region
Solution Approach 1:
The patent applies low bandgap dielectric layers locally only in the high-voltage isolation capacitor region where they are needed for isolation enhancement, while deliberately excluding them from the mixed-signal integrated circuit region to prevent leakage current. This spatially selective application of different material properties resolves the contradiction between isolation capability and leakage prevention.
Solution Approach 2:
The patent segments the semiconductor device into distinct regions: a high-voltage isolation capacitor region containing low bandgap dielectric layers for enhanced isolation, and a mixed-signal integrated circuit region without low bandgap materials to avoid leakage current. This segmentation allows each region to have optimized material composition for its specific function.
3Reliability
If low bandgap dielectric layers are added to the high-voltage isolation capacitor structure, then the isolation barrier is enhanced, but the device structure becomes more complex
Solution Approach 1:
The patent merges the low bandgap dielectric layers with the existing thick oxide interlayer insulating film structure, forming an integrated multi-layer dielectric system. The low bandgap materials are incorporated as additional layers (e.g., between the oxide layers or adjacent to them) rather than separate components, thus enhancing isolation while minimizing structural complexity through consolidation.
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 effectively increases high-voltage isolation while minimizing leakage current in the mixed-signal integrated circuit region, enabling efficient digital signal transfer across the isolation barrier.
Implementation Method 1
Low bandgap materials having a bandgap lower than the thick oxide interlayer insulating film may be incorporated into the high-voltage isolation capacitors to increase the high-voltage isolation.
Implementation Method 2
Capacitive isolation employs high-voltage isolation capacitors to couple data signals across the isolation barrier.
Data Source
AI summary
A semiconductor device including a high-voltage isolation capacitor and a mixed-signal integrated circuit, wherein the high-voltage isolation capacitor includes bottom electrodes, each spaced apart from another, disposed on a substrate; top electrodes disposed on corresponding ones of the bottom electrodes; an inter-metal dielectric layer disposed between the bottom electrodes and the top electrodes; and low bandgap dielectric layers disposed on the inter-metal dielectric layer. Each of the low bandgap dielectric layers is disposed below corresponding ones of the top electrodes, and the low bandgap dielectric layers are absent in the mixed-signal integrated circuit.