Strained Dielectric Capacitor Structure for Low Leakage
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Solution Overview
Problem
As integrated circuit devices downscale, capacitors face reduced available space, leading to leakage currents and decreased capacitance due to thin dielectric films, necessitating a technique to minimize capacitance reduction while reducing leakage current.
Innovation Solution
A capacitor design with a first electrode, a dielectric layer, and a second electrode where the thermal expansion coefficient of the first electrode is greater than that of the dielectric layer, and the work function of the second electrode is higher than the first, with the second electrode being thin and made of materials like tantalum or nickel, and the dielectric layer being tensile-strained to enhance permittivity and block leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the dielectric film is decreased to reduce capacitor size, then the capacitance density is improved, but leakage current increases and capacitance retention deteriorates
Solution Approach 1:
The patent applies parameter changes by introducing tensile strain to the dielectric layer through thermal expansion coefficient mismatch between the first electrode and dielectric layer. This strain modification enhances the dielectric properties and leakage current blocking capability without increasing the dielectric thickness, thereby maintaining miniaturization while improving reliability
Solution Approach 2:
The patent utilizes thermal expansion by designing the first electrode with a thermal expansion coefficient greater than that of the dielectric layer. During cooling after deposition, this mismatch generates tensile strain in the dielectric layer, which improves its electrical properties and leakage resistance, resolving the contradiction between thin film requirements and leakage current blocking
2Volume of moving object
If the thickness of the dielectric film is decreased to reduce capacitor size, then the capacitance density is improved, but capacitance retention deteriorates
Solution Approach 1:
The patent modifies the physical state of the dielectric layer by applying tensile strain through thermal expansion mismatch. This parameter change enhances the dielectric constant and charge retention capability of the thin dielectric film, allowing the capacitor to maintain both miniaturization and improved charge retention performance
Solution Approach 2:
By designing the first electrode with higher thermal expansion coefficient than the dielectric layer, the patent generates tensile strain during thermal cooling that enhances the dielectric properties and charge retention of the thin film, resolving the contradiction between size reduction and charge retention
3Quantity of substance
If a high-permittivity dielectric material is used to increase capacitance, then the capacitance is improved, but leakage current increases due to thin film requirements
Solution Approach 1:
The patent changes the physical state of the high-permittivity dielectric material by applying tensile strain through thermal expansion mismatch. This strain enhancement improves both the permittivity and the leakage current blocking properties, allowing the capacitor to achieve high capacitance without suffering from increased leakage current
Solution Approach 2:
The patent uses thermal expansion coefficient difference between the first electrode and dielectric layer to generate tensile strain that simultaneously enhances permittivity and reduces leakage current in high-permittivity dielectric materials, resolving the contradiction between capacitance enhancement and leakage current reduction
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 design effectively minimizes leakage current and maintains high capacitance by utilizing the difference in thermal expansion coefficients and work functions to strain the dielectric layer, improving its permittivity and stability.
Implementation Method 1
a thermal expansion coefficient of the first electrode is greater than a thermal expansion coefficient of the dielectric layer... the dielectric layer may be tensile-strained in a thickness direction of the dielectric layer
Implementation Method 2
a work function of the second electrode is higher than a work function of the first electrode
Data Source
AI summary
Provided are a capacitor and a semiconductor device including the same. The capacitor includes a first electrode, a dielectric layer over the first electrode, a second electrode between the first electrode and the dielectric layer, and a third electrode over the dielectric layer and in contact with the dielectric layer such that the dielectric layer is between the second electrode and the third electrode. A thermal expansion coefficient of the first electrode may be greater than a thermal expansion coefficient of the dielectric layer, and a work function of the second electrode may be higher than a work function of the first electrode.