MIM Capacitor Nanofiber Protrusions for High Surface Area
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Solution Overview
Problem
Conventional MIM capacitors have limitations in achieving high capacitance per unit area due to constraints in reducing trench width and spacing in silicon devices, which restricts the increase in capacitive surface area without increasing chip surface area.
Innovation Solution
The method involves growing nanofibers with diameters of less than 50 nm on a base surface, forming protrusions that extend into corresponding cavities in the other plate, and coating them with metallic and dielectric layers to increase the capacitive surface area, allowing for denser vertical capacitive surface area without increasing the chip surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the trench width and spacing are reduced to increase capacitive surface area, then the capacitance per unit area is improved, but the manufacturing precision and device reliability deteriorate due to process constraints in silicon devices
Solution Approach 1:
The patent transitions from planar (2D) capacitor plates to vertically extended (3D) structures by growing nanofibers that protrude into the opposing plate's cavity. This dimensional change increases the capacitive surface area without reducing trench width or spacing, thereby improving capacitance per unit area while maintaining manufacturable dimensions.
Solution Approach 2:
The nanofiber protrusions are nested within the cavities of the opposing plate, creating a nested configuration where one structure (nanofiber) is positioned inside the void space of another (cavity). This nested arrangement maximizes the use of available space to increase capacitive surface area without increasing the overall device footprint or compromising manufacturing precision.
2Quantity of substance
If the trench width is reduced to increase vertical capacitive surface area, then the capacitance per unit area is improved, but the device complexity increases due to additional process steps
Solution Approach 1:
The nanofibers are grown in advance (preliminarily) before the formation of the capacitor plates. This preliminary action allows the complex nanofiber structures to be prepared separately, and then integrated into the capacitor structure through subsequent coating steps, thereby increasing capacitance without proportionally increasing overall process complexity.
Solution Approach 2:
The nanofiber structures serve multiple functions: they act as the capacitive element, provide structural support within the cavity, and define the geometry for subsequent coating processes. This multi-functionality reduces the need for separate components and process steps, thereby increasing capacitance per unit area without excessive increases in device complexity.
3Quantity of substance
If nanofibers with diameter less than 50 nm are used to increase capacitive surface area, then the capacitance per unit area is significantly improved, but the ease of manufacture deteriorates due to difficulty in controlling nanofiber dimensions
Solution Approach 1:
The patent controls nanofiber dimensions by adjusting growth parameters such as catalyst particle size, deposition temperature, and growth time. By changing these parameters, the nanofiber diameter can be precisely controlled to be less than 50 nm, thereby achieving high capacitance per unit area while maintaining ease of manufacture through parameter optimization.
Solution Approach 2:
Catalyst particles are used as intermediaries to control nanofiber growth. The catalyst particles serve as templates that dictate the nanofiber diameter, allowing indirect control of the final nanofiber dimensions. This intermediary approach simplifies the manufacturing process by decoupling the control of nanofiber diameter from direct mechanical manipulation.
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
This approach significantly enhances the capacitance per unit area of MIM capacitors, achieving capacitance values between 6 and 50 fF/μm², which is 650% to 960% higher than standard 3D MIM capacitors, by providing a more efficient capacitive surface area through the use of nanofibers.
Implementation Method 1
before growing the nanofibers, depositing catalytic particles over the base surface, the particles providing a starting point for subsequent nanofiber growth
Implementation Method 2
coating the nanofiber with a metallic layer
Implementation Method 3
subsequently coating the metallic layer with a dielectric layer
Data Source
AI summary
A method of forming a metal-insulator-metal capacitor having top and bottom plates separated by a dielectric layer, one of the top and bottom plates having at least one protrusion extending into a corresponding cavity in the other of the top and bottom plates, the method including the steps of growing one or more nanofibers on a base surface.