Porous Silicon Capacitor Structure for Higher Areal Capacitance

The patent applies local quality by providing porous parts only in specific regions (opening regions and non-opening regions) of the silicon substrate rather than uniformly throughout. This localized porosity increases electrostatic capacitance in areas where it is needed while preserving substrate strength in other areas. The porous parts are strategically positioned to maximize capacitance without compromising overall structural integrity.

The patent creates a composite structure by combining porous silicon regions with solid silicon regions in the substrate. This composite approach allows the porous parts to provide high electrostatic capacitance while the solid parts maintain mechanical strength. The conductor layers and dielectric layers further contribute to this composite structure, creating a multi-material system that optimizes both electrical and mechanical properties.

The patent increases electrode area by utilizing the vertical dimension through porous parts that extend into the substrate thickness direction. This three-dimensional electrode configuration allows for significantly increased surface area without proportionally increasing the planar footprint. The porous structure creates multiple interfaces between conductor and dielectric layers, effectively multiplying the capacitive area within a compact volume.

The patent employs a nested structure where conductor layers and dielectric layers are alternately stacked within the porous parts of the substrate. This nested arrangement of multiple layers within the porous regions maximizes the use of available space, creating a compact high-capacitance structure that fits within the substrate without requiring excessive lateral expansion.