Cup-Shaped MIM Capacitor Layout for Lower Resistance and Stable Breakdown
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Solution Overview
Problem
Conventional MIM capacitors are expensive to manufacture, require multiple additional mask layers and process steps, and have inefficient area usage, high series resistance, and unpredictable breakdown voltage due to hillock formation.
Innovation Solution
A MIM capacitor module design that includes a bottom electrode cup with a shortened sidewall, an insulator with a lateral flange covering the sidewall, and a top electrode formed within the insulator cup, allowing for concurrent construction with interconnect structures and potentially reducing the need for additional photomasks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MIM capacitor fabrication process is used, then capacitor performance is achieved, but manufacturing cost increases due to multiple additional mask layers and process steps
Solution Approach 1:
The patent merges the capacitor fabrication process with the existing interconnect structure formation process. The bottom electrode cup, insulator, and top electrode are formed concurrently with the metal layers and dielectric regions, eliminating the need for separate capacitor fabrication steps and additional photomasks.
Solution Approach 2:
The fabrication process achieves multiple functions simultaneously: forming the capacitor structure (bottom electrode cup, insulator, top electrode) and creating the interconnect structure (metal layers, via regions). This multi-functional approach reduces overall process complexity and manufacturing cost.
2Reliability
If conventional MIM capacitor design is used, then capacitor function is achieved, but area usage efficiency decreases due to large silicon area requirements
Solution Approach 1:
The patent transitions from planar capacitor structures to three-dimensional cup-shaped structures. The bottom electrode cup and top electrode are formed with vertical sidewalls, utilizing the vertical dimension to increase capacitance density without proportionally increasing the horizontal silicon area.
Solution Approach 2:
The insulator is nested within the bottom electrode cup structure, and the top electrode is nested within the insulator. This nested configuration maximizes the use of available space and improves area efficiency.
3Length of stationary object
If thin top plate is used in conventional MIM capacitor, then vertical thickness constraint is satisfied, but series resistance increases
Solution Approach 1:
The top electrode is formed as a cup-shaped structure with vertical sidewalls instead of a thin planar plate. This three-dimensional configuration increases the effective conductive cross-section and reduces series resistance while maintaining compliance with vertical thickness constraints between metal layers.
4Ease of manufacture
If conventional fabrication process with heated steps is used, then capacitor structure is formed, but breakdown voltage becomes low and unpredictable due to hillock formation
Solution Approach 1:
The patent removes or minimizes the heated fabrication steps that cause hillock formation on the bottom plate. By avoiding high-temperature processing, the formation of unwanted hillocks is prevented, ensuring consistent and predictable breakdown voltage characteristics.
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
The proposed design achieves lower manufacturing costs, improved spatial density, consistent breakdown voltage, and reduced series resistance by avoiding hillock formation and enabling efficient integration with existing IC fabrication processes.
Implementation Method 1
The bottom electrode cup sidewall may be shortened (allowing formation of the insulator flange extending thereover) by a high-density plasma (HDP) sputtering process to remove the upper portion or lip of the bottom electrode cup sidewall.
Data Source
AI summary
A metal-insulator-metal (MIM) capacitor includes a bottom electrode cup, an insulator, and a top electrode. The bottom electrode cup includes a laterally-extending bottom electrode cup base and a bottom electrode cup sidewall extending upwardly from the laterally-extending bottom electrode cup base. The insulator includes an insulator cup formed in an opening defined by the bottom electrode cup, and an insulator flange extending laterally outwardly from the insulator cup sidewall and extending laterally over an upper surface of the bottom electrode cup sidewall. The top electrode is formed in an opening defined by the insulator cup. The top electrode is insulated from the upper surface of the bottom electrode cup sidewall by the insulator flange.