Ferroelectric Capacitor Stack for Impedance-Controlled Capacitance Boosting
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Solution Overview
Problem
The challenge lies in enhancing the capacitance of scaled-down devices such as transistors and capacitors, which require materials with high dielectric constants to effectively boost capacitance when a voltage is applied, while maintaining controlled impedance and current density to achieve a capacitance boosting effect.
Innovation Solution
A method and structure involving a capacitor with a ferroelectric film and a dielectric film, where the impedance of both films is controlled to achieve a capacitance boosting operating voltage, determined by specific equations, ensuring a high dielectric constant and controlled current density, thereby enhancing capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If materials with high dielectric constant are used to boost capacitance in scaled-down devices, then capacitance is improved, but impedance control becomes more difficult
Solution Approach 1:
The patent employs a composite structure consisting of a ferroelectric film and a dielectric film stacked together. The ferroelectric film provides high dielectric constant for capacitance boosting, while the dielectric film serves as an impedance control layer. This composite material approach allows simultaneous achievement of high capacitance and controlled impedance in scaled-down devices.
Solution Approach 2:
The patent adjusts the thickness parameters of both the ferroelectric film and dielectric film to optimize performance. By controlling the thickness ratio and absolute values, the system achieves the desired capacitance while maintaining proper impedance characteristics. This parameter optimization resolves the contradiction between capacitance enhancement and impedance control.
2Quantity of substance
If voltage is applied to achieve capacitance boosting effect, then dielectric constant increases sharply, but current density becomes uncontrolled
Solution Approach 1:
The dielectric film acts as an intermediary layer between the ferroelectric film and the electrodes. It mediates the electrical field distribution, allowing the ferroelectric film to achieve high dielectric constant through polarization while the dielectric film controls the overall current density. This intermediary structure enables capacitance boosting without excessive current density.
3Volume of moving object
If device size is scaled down, then integration density is improved, but available thickness for capacitance is reduced
Solution Approach 1:
The patent utilizes thin film structures for both the ferroelectric and dielectric layers, enabling capacitance functionality in scaled-down devices. The thin film approach maintains sufficient capacitance through high dielectric constant materials while accommodating reduced device dimensions. This flexible thin film structure resolves the contradiction between miniaturization and capacitance maintenance.
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 effectively increases capacitance by controlling the impedance and angular frequency of the films, achieving a significant capacitance boosting effect with controlled current density and high dielectric constant, suitable for scaled-down devices.
Implementation Method 1
a ferroelectric film provided between the first electrode and the second electrode... the capacitance boosting effect may sharply increase the dielectric constant of a capacitor when a voltage is applied to the capacitor
Implementation Method 2
there is an increasing demand for materials having a high dielectric constant and structures thereof... the capacitance boosting effect may sharply increase the dielectric constant of a capacitor
Data Source
AI summary
A capacitor comprises a first electrode, a second electrode provided on the first electrode, a ferroelectric film provided between the first electrode and the second electrode, and a dielectric film provided between the ferroelectric film and the second electrode, impedance of the ferroelectric film and impedance of the dielectric film are determined such that a control voltage applied between the first electrode and the second electrode is equal to a capacitance boosting operating voltage, and the capacitance boosting operating voltage is determined by the following equation:VMAX=(1+<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[LeftBracketingBar]"</annotation></semantics>Z2<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[RightBracketingBar]"</annotation></semantics><semantics definitionURL="">❘<annotation encoding="Mathematica">"\[LeftBracketingBar]"</annotation></semantics>Z1<semantics definitionURL="">❘<annotation encoding="Mathematica">"\[RightBracketingBar]"</annotation></semantics>)tFEFMwhere VMAX is a capacitance boosting operating voltage, Z1 is impedance of the ferroelectric film, Z2 is impedance of the dielectric film, tF is a thickness of the ferroelectric film, and EFM is an electric field applied to the ferroelectric film having a maximum polarization.