Capacitor Device with Variable Dielectric Thickness for Wideband Impedance Control
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Solution Overview
Problem
Conventional decoupling capacitors on circuit substrates face challenges in reducing impedance over a wide frequency band, leading to unstable power-supply voltage and high-frequency noise issues in high-speed electronic components, due to limitations in minimizing parasitic inductance and requiring complex electrical design considerations.
Innovation Solution
A capacitor device is developed with multiple capacitors having different dielectric film thicknesses, connected in parallel between power-supply and ground lines, allowing for impedance reduction across a wide frequency band without altering the basic capacitor structure or inductance, enabling easy electrical design and high-density packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wiring distance between the LSI chip and the capacitor is minimized by placing the decoupling capacitor directly under the LSI chip, then the parasitic inductance is reduced, but the impedance cannot be reduced over a wider frequency band
Solution Approach 1:
The patent divides a single capacitor into multiple capacitors (first capacitor and second capacitor) with different electrostatic capacities. Each capacitor targets different frequency ranges, with the first capacitor (larger capacity) handling lower frequencies and the second capacitor (smaller capacity) handling higher frequencies. This segmentation allows the decoupling system to effectively cover a wider frequency band while maintaining low impedance across all ranges.
Solution Approach 2:
The patent changes the electrostatic capacity parameter of the capacitors by using different dielectric film thicknesses. The first capacitor has a thicker dielectric film (500-1000 nm) for higher capacity, while the second capacitor has a thinner dielectric film (100-300 nm) for lower capacity. This parameter variation enables each capacitor to resonate at different frequencies, expanding the overall frequency coverage.
2Adaptability or versatility
If multiple capacitors with different electrostatic capacities are used to reduce impedance over a wide frequency band, then the frequency band coverage is improved, but the device complexity increases
Solution Approach 1:
The patent merges multiple capacitors with different electrostatic capacities into a single integrated capacitor device. Both the first capacitor and second capacitor are formed on the same substrate with shared structural elements, including the lower electrode formed by the LSI chip pad and the upper electrode formed as a single conductive layer. This merging approach achieves wide frequency band coverage while avoiding the complexity of multiple separate capacitor components.
Solution Approach 2:
The single upper electrode serves multiple functions by forming the upper electrode for both the first capacitor and the second capacitor. This universal structure eliminates the need for separate upper electrodes and complex interconnections, simplifying the overall device structure while maintaining the functionality of multiple capacitors with different capacities.
3Device complexity
If conventional single-capacitor designs are used, then the device complexity is minimized, but the impedance reduction effect is limited to narrow frequency bands
Solution Approach 1:
The patent applies local quality by creating regions with different dielectric film thicknesses within the same capacitor structure. The first region has a thicker dielectric film (500-1000 nm) for the first capacitor, while the second region has a thinner dielectric film (100-300 nm) for the second capacitor. This local variation in dielectric thickness allows each region to function at different frequencies, achieving wide bandwidth coverage without requiring fundamentally different capacitor structures.
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 solution effectively reduces impedance across a wide frequency range, stabilizes power-supply voltage, and minimizes high-frequency noise, while reducing packaging costs and parasitic inductance, allowing for direct integration under electronic components.
Implementation Method 1
each of the dielectric films in the plurality of capacitors has a different film thickness... a plurality of capacitors each composed of the lower electrode, the dielectric film, and the upper electrode are arranged on the substrate respectively
Implementation Method 2
a plurality of dielectric films formed on the plurality of lower electrodes respectively in a state that the dielectric films are separated mutually
Data Source
AI summary
In a capacitor device of the present invention includes a substrate, a plurality of lower electrodes formed on the substrate, a plurality of dielectric films formed on a plurality of lower electrodes respectively in a state that the dielectric films are separated mutually, and upper electrodes formed on a plurality of dielectric films respectively, a plurality of capacitors each composed of the lower electrode, the dielectric film, and the upper electrode are arranged on the substrate respectively, and each of the dielectric films in a plurality of capacitors has a different film thickness.