MIM Capacitor Dielectric Stack for High Capacitance and Low Leakage
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Solution Overview
Problem
Metal-Insulator-Metal (MIM) capacitors face issues with breakdown voltage (VBD) and leakage current (ILK) degradation due to the use of high-k materials for achieving high capacitance, which affect their reliability.
Innovation Solution
A dielectric structure with a multilayer design is employed, comprising a first and third dielectric layer with higher conduction band barrier heights flanking a second dielectric layer with a higher k-value, to enhance electron barrier height and reduce leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-k materials are used to achieve high capacitance, then capacitance is improved, but breakdown voltage and leakage current degradation occur
Solution Approach 1:
The dielectric layer is segmented into multiple sub-layers with different k-values. The first and third sub-layers have lower k-values but higher conduction band barrier heights, while the second sub-layer has a higher k-value. This segmentation allows the capacitor to achieve high capacitance through the high-k middle layer while the low-k outer layers provide protection against leakage current and breakdown voltage degradation.
Solution Approach 2:
Different regions of the dielectric structure are assigned different material properties. The inner region (second sub-layer) has high k-value for capacitance, while the outer regions (first and third sub-layers) have lower k-values but higher conduction band barrier heights. This local quality differentiation optimizes both capacitance performance and reliability by placing appropriate materials in appropriate locations.
2Quantity of substance
If high-k materials are used to achieve high capacitance, then capacitance is improved, but leakage current increases
Solution Approach 1:
The first and third dielectric sub-layers act as intermediary layers between the metal electrodes and the high-k second dielectric sub-layer. These intermediary layers have higher conduction band barrier heights that block leakage current while allowing the high-k middle layer to maintain capacitance. This mediator approach eliminates the direct contact between high-k material and electrodes, reducing leakage pathways.
3Quantity of substance
If high-k materials are used to achieve high capacitance, then capacitance is improved, but breakdown voltage decreases
Solution Approach 1:
The dielectric structure is segmented into three sub-layers where the outer first and third sub-layers with higher conduction band barrier heights provide protection against breakdown voltage. The inner second sub-layer with high k-value provides capacitance. This segmentation distributes the electrical stress across layers with appropriate properties, preventing premature breakdown while maintaining high capacitance.
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 multilayer dielectric structure improves the reliability of MIM capacitors by reducing leakage current by about 88% and maintaining high capacitance, while enhancing breakdown voltage.
Implementation Method 1
The first dielectric layer and the third dielectric layer each include higher conduction band barrier height than the second dielectric layer to avoid leakage current
Implementation Method 2
The second dielectric layer has a k-value greater than the first and third dielectric layers
Data Source
AI summary
A method of forming a capacitor includes the following steps. A first electrode is formed over a substrate. A first dielectric layer is formed over the first electrode. A second dielectric layer is formed over the first dielectric layer. The first dielectric layer has a conduction band barrier height higher than a conduction band barrier height of the second dielectric layer. A second electrode is formed over the second dielectric layer.