Thin Film Capacitor Electrode Laminate Structure for ESR Control
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Solution Overview
Problem
Thin film capacitors experience increased equivalent series resistance (ESR) due to metal diffusion between layers when exposed to heat, degrading their performance.
Innovation Solution
A thin film capacitor design featuring a second electrode with a laminate structure comprising a first metallic layer, an intermediate layer, and a second metallic layer, where the intermediate layer has alternating sublayers of different metals to suppress metal diffusion, and a method of producing such capacitors using a carousel-type sputtering apparatus to form these layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat is applied to the thin film capacitor, then the capacitor can be packaged or processed, but metal diffusion occurs between layers causing ESR to increase
Solution Approach 1:
The second electrode is segmented into multiple thin metal sublayers (first metal sublayer and second metal sublayer) alternating with intermediate layers. This segmentation prevents bulk metal diffusion by creating multiple barriers, allowing heat treatment to proceed while maintaining low ESR through suppressed atomic migration between metal layers.
Solution Approach 2:
Intermediate layers are introduced as mediator substances between the first and second metal layers. These intermediate layers act as diffusion barriers that prevent direct contact and atomic diffusion between dissimilar metals (e.g., Ni and Cu), enabling thermal processing without harmful metal interdiffusion that would increase ESR.
2Reliability
If the intermediate layer has more laminate structures, then metal diffusion suppression improves, but the electric resistance of the intermediate layer increases
Solution Approach 1:
The thickness of each metal sublayer and intermediate layer is precisely controlled within specific ranges (metal sublayer: 1-20 nm, intermediate layer: 1-10 nm). By optimizing these dimensional parameters, the structure provides sufficient diffusion barriers through multiple laminate interfaces while maintaining adequate conductivity, preventing excessive resistance buildup.
Solution Approach 2:
Different regions of the electrode structure have different compositions and thicknesses optimized for their specific functions. The metal sublayers provide conductivity with controlled thickness for low resistance, while the intermediate layers provide diffusion barrier functionality. This local optimization allows the overall structure to achieve both low ESR and effective diffusion suppression.
3Reliability
If the thickness of metal sublayers is increased, then the diffusion suppression effect improves, but the mutual diffusion within the metal sublayer increases
Solution Approach 1:
Instead of using thick single metal layers, the structure segments the metal content into thin alternating sublayers (1-20 nm each) separated by intermediate layers. This segmentation prevents through-thickness diffusion paths that would occur in thick layers, while the multiple interfaces provide cumulative diffusion suppression without allowing significant atomic migration within each thin sublayer.
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 laminate structure effectively suppresses metal diffusion and maintains low ESR even under heat exposure, enhancing the reliability and performance of the capacitors.
Implementation Method 1
a step of having the first target release the metal element M1 therefrom during the step of alternately approaching the dielectric substance thereto to form a first metallic layer on the dielectric substance
Data Source
AI summary
A thin film capacitor comprises a first electrode, a second electrode, and a dielectric substance disposed between the first electrode 10 and the second electrode. The second electrode has a first metallic layer, an intermediate layer, and a second metallic layer in sequence in this order from the side of the dielectric substance. The first metallic layer contains a metal element M1 as a main component, and the second metallic layer contains a metal element M2 different from the metal element M1 as a main component. The intermediate layer has one or more laminate structures each having a second metal sublayer containing the metal element M2 as a main component and a first metal sublayer containing the metal element M1 as a main component in sequence from the side of the first metallic layer toward the side of the second metallic layer.