MIM Capacitor Via Sublayer and Corrugated Plates
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Solution Overview
Problem
Current metal-insulator-metal (MIM) capacitors face challenges with high series resistance and leakage issues, particularly in miniaturized integrated circuits where smaller dimensions and increased functionality demand improved performance.
Innovation Solution
The introduction of a via underneath the bottom plate of the MIM capacitor and the formation of a corrugated shape to increase the plate surface area, allowing for a thicker dielectric layer and reducing leakage, while also using a metal sublayer to mitigate contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a via is introduced underneath the bottom plate of the MIM capacitor, then series resistance is reduced, but device complexity increases
Solution Approach 1:
The capacitor structure is segmented into multiple components: top plate, bottom plate, and an additional metal sublayer introduced underneath the bottom plate. This segmentation allows the metal sublayer to function as a separate resistance-reducing element while maintaining the integrity of the original capacitor plates, thus reducing series resistance without compromising structural stability
Solution Approach 2:
A metal sublayer is introduced as an intermediary element between the bottom plate and the underlying via structure. This metal sublayer acts as a mediator that provides additional conductive pathways, reducing the overall series resistance of the capacitor while distributing electrical stress and improving reliability
2Quantity of substance
If a corrugated shape is formed to increase plate surface area, then capacitance is increased, but manufacturing precision requirements increase
Solution Approach 1:
The capacitor plates are formed with a corrugated (curved/wavy) shape instead of flat surfaces. This curvature increases the effective surface area of the plates without increasing the lateral footprint of the capacitor, thereby increasing capacitance. The corrugated structure is achieved through controlled deposition and etching processes that create repetitive wave-like patterns
Solution Approach 2:
The plate surface is extended into the vertical dimension by creating corrugations with multiple peaks and valleys. This dimensional transformation allows the plate surface area to increase significantly within the same planar footprint, effectively increasing capacitance without requiring larger device area or more complex multi-layer stacking
3Reliability
If a thicker dielectric layer is used to mitigate leakage, then leakage is reduced, but capacitance density decreases
Solution Approach 1:
The corrugated plate shape creates multiple peaks and valleys that increase the effective surface area of the plates. Since capacitance is directly proportional to plate surface area, the corrugated structure compensates for the reduced capacitance density caused by the thicker dielectric layer, maintaining overall capacitance while benefiting from improved leakage characteristics
Solution Approach 2:
The dielectric layer thickness is increased as a parameter change to reduce leakage current and improve reliability. While this naturally reduces capacitance per unit area, the simultaneous introduction of corrugated plates with increased surface area compensates for this reduction, achieving both lower leakage and maintained capacitance through the combined effect of thicker dielectric and larger plate area
Data Source
AI summary
Embodiments of the present invention provide improved metal-insulator-metal (MIM) capacitors. In embodiments, series resistance is reduced by forming a via underneath the bottom plate of a MIM capacitor, leading to a metallization layer or intermediate metal sublayer. In embodiments, the MIM capacitor is formed with a corrugated shape to increase the plate surface area, allowing a thicker dielectric to be used, thereby mitigating leakage issues.