Integrated Silicon Capacitor Dielectric Stack for 900 V Reliability
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Solution Overview
Problem
Current technologies fail to produce silicon capacitors with sufficient capacitance density and dielectric strength for operating voltages above 900 V, leading to the predominance of ceramic or film capacitors in this voltage range, while existing silicon nitride-based solutions suffer from high defect concentration and leakage currents.
Innovation Solution
An integrated capacitor design utilizing a dielectric layer structure comprising SiO2, Si3N4, and non-stoichiometric silicon nitride (SixNy) layers, where the SixNy layer has a higher silicon-to-nitrogen ratio, reducing mechanical stress and increasing dielectric strength, and a trench structure to enhance capacitance density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If non-stoichiometric silicon nitride (SixNy) is used to reduce mechanical stress, then mechanical stress is reduced, but leakage current increases due to higher defect concentration
Solution Approach 1:
The patent employs a composite dielectric layer structure combining SiO2, Si3N4, and SixNy layers. Each material contributes different properties: SiO2 provides low defect concentration and good insulation, Si3N4 provides high dielectric constant and mechanical strength, and SixNy provides stress compensation. The combination allows the capacitor to achieve low leakage current while managing mechanical stress through the synergistic effect of multiple materials.
Solution Approach 2:
The patent applies different dielectric materials at different locations within the capacitor structure. SiO2 is used in regions where low leakage is critical, Si3N4 is used where high capacitance density is needed, and SixNy is used where stress compensation is required. This spatial differentiation of material properties allows optimization of both leakage current and mechanical stress in their respective critical regions.
2Strength
If thick dielectric layers are used to increase dielectric strength, then dielectric strength is improved, but manufacturing complexity increases and integration density is reduced
Solution Approach 1:
The patent divides the thick dielectric layer into multiple thinner sub-layers of different materials (SiO2, Si3N4, SixNy). Each sub-layer can be manufactured using standard thin-film deposition processes, avoiding the need for single thick-layer deposition which would be complex and prone to defects. The segmented structure achieves the required total dielectric strength while maintaining compatibility with existing manufacturing capabilities.
Solution Approach 2:
By using composite dielectric materials with different properties, the patent achieves high dielectric strength without requiring excessive thickness. The high-k Si3N4 layer provides enhanced capacitance per unit thickness, allowing the capacitor to achieve target dielectric strength with a more manageable overall layer thickness, thereby reducing manufacturing complexity and improving integration density.
3Reliability
If stoichiometric silicon nitride (Si3N4) is used to achieve low leakage current, then leakage current is reduced, but mechanical stress increases causing substrate distortion
Solution Approach 1:
The patent uses SixNy layer as a counterbalancing element to compensate for the tensile stress introduced by Si3N4 layers. The SixNy material has different stress characteristics that can offset the mechanical stress from Si3N4, reducing net substrate distortion. This stress compensation allows the capacitor to utilize Si3N4's low leakage properties without suffering from excessive mechanical stress.
Solution Approach 2:
The composite structure combines Si3N4 and SixNy in specific thickness ratios and configurations. The Si3N4 provides low leakage current, while the SixNy provides stress compensation. By carefully designing the composition and arrangement of these composite materials, the patent achieves both low leakage current and controlled mechanical stress simultaneously.
Data Source
AI summary
Integrated capacitor including a first electrode structure, a second electrode structure, and an interposed dielectric layer structure. The dielectric layer structure includes a layer combination having an SiO2 layer, an Si3N4 layer, and an SixNy layer. The SixNy layer includes a non-stoichiometric silicon nitride material with an increased proportion of silicon.