Nested MIM Capacitor Structure for High Capacitance and Breakdown

The patent merges the capacitor electrode formation with the existing interconnect metal layers. The top electrode is formed as part of the interconnect metal layer Mx+1 during the normal damascene process, eliminating the need for separate capacitor-specific mask and etch steps. This integration maintains manufacturing precision while reducing process complexity and cost.

The interconnect metal layer Mx+1 serves dual functionality: it acts as both the interconnect wiring layer and the top electrode of the MIM capacitor. This multi-functionality approach eliminates dedicated capacitor fabrication steps while maintaining the required electrical performance and precision.

The patent transitions from a planar capacitor geometry to a three-dimensional nested structure. The nested configuration with vertical sidewalls increases the effective capacitance area without increasing the insulator thickness, thereby maintaining breakdown voltage while achieving higher capacitance values.

The patent employs a nested capacitor structure where one capacitor is formed within another sharing common electrodes. This nested arrangement multiplies the effective capacitance area within the same vertical space, achieving higher capacitance without compromising the insulator thickness required for breakdown voltage.

The patent utilizes vertical sidewalls of cup-shaped insulators to create additional capacitance area in the vertical dimension. This allows achieving higher capacitance without increasing the horizontal footprint or the overall device height, as the additional capacitance area is formed along the vertical interfaces rather than requiring increased layer spacing.

The patent employs cup-shaped insulators with curved vertical sidewalls instead of flat planar structures. This curvature increases the surface area for capacitance formation along the vertical interfaces, achieving higher capacitance density within the same device height constraints.

The patent forms the top electrode as a three-dimensional structure with vertical sidewalls extending down into the insulator cavity. This vertical extension provides additional conductive path area, effectively reducing serial resistance without requiring increased horizontal thickness or additional vertical spacing between metal layers.

The nested structure allows the top electrode to extend vertically into the capacitor cavity, creating multiple parallel conductive paths. This nested electrode configuration reduces serial resistance by increasing the effective conductive cross-section without consuming additional vertical spacing between interconnect layers.