Double-Sided SOI Capacitor Trench Design
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Solution Overview
Problem
Current capacitors, such as multi-layer ceramic capacitors and 3D silicon-based capacitors, face challenges in achieving high capacitance density while maintaining mechanical strength and cost-effectiveness, particularly due to complex fabrication processes and high production costs.
Innovation Solution
A double-sided capacitor design utilizing a Silicon-On-Insulator (SOI) substrate with trench structures etched on both sides, where the trenches do not penetrate through the intermediate insulating layer, allowing for increased capacitance without compromising mechanical strength, and using insulating and conductive materials to form electrodes that are electrically connected across the substrate layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If deep trench etching is performed to increase capacitance density, then capacitance increases, but mechanical strength deteriorates and fabrication complexity increases
Solution Approach 1:
The patent utilizes the SOI substrate's intermediate insulating layer to create capacitance in a different dimensional approach. Instead of only deepening trenches vertically, the invention uses the existing thickness of the intermediate insulating layer as a capacitance-forming dimension, effectively utilizing the z-dimension of the substrate without requiring deep penetrating trenches. This maintains mechanical integrity while achieving high capacitance density.
Solution Approach 2:
The SOI substrate's intermediate insulating layer serves dual purposes: it provides mechanical support and electrical isolation while simultaneously functioning as the dielectric layer for capacitance formation. The substrate itself 'services' the capacitance function through its inherent layered structure, eliminating the need for separate deep trench etching and complex dielectric stacking.
2Quantity of substance
If multiple layers of dielectric and conductive materials are stacked to increase capacitance density, then capacitance increases, but fabrication complexity and cost increase
Solution Approach 1:
The SOI substrate's intermediate insulating layer performs multiple functions simultaneously: it acts as the dielectric for capacitance, provides electrical isolation between front and back surfaces, and maintains mechanical structural integrity. This multi-functionality eliminates the need for separate dielectric layers and complex stacking procedures, simplifying the fabrication process while achieving high capacitance density.
Solution Approach 2:
The invention extracts and utilizes the intermediate insulating layer that is already present in the SOI substrate structure. By taking advantage of this pre-existing layer rather than adding multiple separate dielectric layers, the fabrication process is simplified while still achieving the desired capacitance density through the dual-sided electrode configuration.
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 approach enhances capacitance by leveraging the substrate capacitance of the SOI wafer while avoiding the complexity and cost of deep trench etching, resulting in a more robust and cost-effective capacitor design.
Implementation Method 1
increases a capacitance by utilizing a substrate capacitance of an SOI (Silicon-On-Insulator) substrate itself
Data Source
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AI summary
Embodiments of the present application relate to a double-sided capacitor and a method for fabricating the same. The double-sided capacitor includes: etching trenches (105, 106) having depths not reaching an intermediate insulating layer and trench structures (107, 108) having depths exceeding the intermediate insulating layer on both sides of an SOI substrate; and sequentially depositing an insulating dielectric film and a conductive material on surfaces of the trenches (105, 106) and the trenches (107, 108), where the insulating material at a bottom of the trenches (107, 108) needs to be removed, and the trenches (107, 108) are filled with the conductive material to form conductive channels. The upper conductive channel of the SOI substrate is insulated from an upper layer and is electrically connected to a lower layer; and the lower conductive channel is insulated from the lower layer and is electrically connected to the upper layer. Therefore, the double-sided capacitor of the embodiment of the present application not only avoids etching the trench penetrating through the substrate so that an entire structure has stronger mechanical strength, but also a capacitance is larger utilizing a substrate capacitance of an SOI wafer itself.