Stacked Semiconductor Capacitor Structure for High Density and Low Leakage
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Solution Overview
Problem
Existing semiconductor capacitor elements face challenges in achieving high capacitance density, sufficient withstand voltage, and low leakage current, particularly for applications like image sensors, where downsizing and improving dynamic range are desired.
Innovation Solution
A semiconductor device is designed with stacked capacitor elements, including a first capacitor with a trench portion and a second capacitor without a trench, allowing for parallel or series connections to optimize capacitance density and leakage current characteristics, with contact plugs formed to avoid etching damage to dielectric layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the dielectric film thickness is reduced to increase capacitance density, then the capacitance density is improved, but the withstand voltage characteristics deteriorate and leakage current increases
Solution Approach 1:
The capacitor element is divided into two separate capacitor elements (first capacitor element and second capacitor element) that are electrically connected in parallel. Each capacitor element has its own dielectric layer with different thickness characteristics, allowing the system to achieve high capacitance density while maintaining reliability through distributed architecture
Solution Approach 2:
The invention transitions from a single-plane capacitor structure to a stacked three-dimensional structure where capacitor elements are arranged in vertical layers. This dimensional change allows increased capacitance density without proportionally reducing dielectric thickness, as the effective capacitance is accumulated across multiple layers
2Quantity of substance
If the electrode area is increased by using a three-dimensional structure to improve capacitance density, then the capacitance density is improved, but the device complexity increases
Solution Approach 1:
The first and second capacitor elements are merged into a single integrated structure with shared components. The first electrode of the second capacitor element serves as the second electrode of the first capacitor element, reducing the total number of discrete components and simplifying the overall device structure while achieving increased capacitance density
Solution Approach 2:
The second electrode of the first capacitor element and the first electrode of the second capacitor element are implemented as a single universal electrode that serves dual functions. This multi-functional design reduces device complexity by eliminating redundant components while maintaining the required capacitance performance
3Quantity of substance
If multiple capacitor elements are electrically connected in parallel to increase capacitance density, then the capacitance density is improved, but the leakage current increases
Solution Approach 1:
Different regions of the capacitor structure have different dielectric layer thicknesses optimized for their specific functions. The first dielectric layer has thickness optimized for one capacitor element while the second dielectric layer has thickness optimized for the other, allowing each region to contribute differently to overall performance and minimizing total leakage current while achieving high capacitance density
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 provides a semiconductor device with enhanced capacitance density and reduced leakage current, enabling high-quality imaging devices with improved dynamic range and reduced pixel size, while maintaining reliable electrical connections.
Implementation Method 1
When the permittivity of a dielectric material is defined as ε, the permittivity of a vacuum is defined as ε0, the dielectric film thickness is defined as t, and the electrode area is defined as S, a capacitance C of a capacitor element is represented as C=(ε×ε0×S)/t
Data Source
AI summary
A semiconductor device includes: a first capacitor element that includes a first electrode, a second electrode, and a dielectric layer positioned between the first electrode and the second electrode; and a second capacitor element that includes a third electrode and an insulating layer positioned between the second electrode and the third electrode. The first capacitor element includes at least one first trench portion.