BEOL MIM Capacitor Plate Layout for Lower Leakage and TDDB
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Solution Overview
Problem
Metal-Insulator-Metal (MIM) capacitors in semiconductor integrated circuits face challenges such as leakage and reduced time-dependent-dielectric-breakdown (TDDB) reliability due to patterning issues and electrostatic stresses, particularly in back-end-of-line (BEOL) structures, where conductor plate layers of different dimensions can lead to step shapes and intensified electric fields.
Innovation Solution
The implementation of odd-number-layer-enclosure and even-number-layer-enclosure configurations in MIM structures, where conductor plate layers are arranged to enclose each other, minimizing leakage and TDDB by optimizing the dimensions and arrangements of conductor plate layers to distribute electric fields more evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conductor plate layers of different dimensions are used in MIM structures, then the surface area and capacitance are increased, but step shapes are formed and electric fields are intensified leading to leakage and reduced TDDB reliability
Solution Approach 1:
The patent divides the conductor plate structure into multiple segments with different dimensions (first conductor plate layer with larger area, second conductor plate layer with smaller area). This segmentation allows the structure to achieve larger total surface area for capacitance while managing the electric field distribution through the insulator layer, thereby improving TDDB reliability despite the area increase.
Solution Approach 2:
The patent applies different dimensions and configurations to different parts of the conductor plate structure. The first conductor plate layer has a larger area than the second conductor plate layer, creating localized variations in the electric field distribution. This local quality approach allows optimization of capacitance in certain regions while maintaining reliability in others by managing the step shapes and field intensification through the insulator layer.
2Area of moving object
If conductor plate layers of different dimensions are used in MIM structures, then the surface area and capacitance are increased, but patterning issues and electrostatic stresses increase leading to leakage
Solution Approach 1:
The patent segments the conductor plate structure into multiple layers with different dimensions, which helps manage the electrostatic stresses and reduce leakage. By dividing the structure into a first conductor plate layer and a second conductor plate layer separated by an insulator layer, the patent distributes the electric field more effectively, reducing the harmful effects of electrostatic stress while maintaining increased surface area.
Solution Approach 2:
The insulator layer acts as an intermediary between the first conductor plate layer and the second conductor plate layer. This intermediary layer manages the electrostatic stresses and electric field distribution between the conductor plates of different dimensions, preventing direct field intensification at the interfaces and thereby reducing leakage while allowing the structure to achieve larger surface area.
3Reliability
If conductor plate layers are arranged to enclose each other, then leakage and TDDB are reduced, but device complexity increases
Solution Approach 1:
The patent implements a nested configuration where the second conductor plate layer is positioned within the area of the first conductor plate layer, and vice versa for subsequent layers. This nesting approach creates an enclosing structure that manages electric field distribution and reduces leakage while maintaining a relatively compact and manufacturable design, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent transitions from a two-dimensional planar arrangement to a three-dimensional stacked configuration with conductor plate layers at different vertical levels. This dimensionality change allows the conductor plates to enclose each other in the vertical dimension, improving leakage reduction and TDDB reliability while maintaining a compact footprint that doesn't excessively increase overall device complexity.
Data Source
AI summary
A device structure according to the present disclosure includes a passivation layer, a first conductor plate layer disposed on the passivation layer, a second conductor plate layer disposed over the first conductor layer, a third conductor plate layer disposed over the second conductor layer, and a fourth conductor plate layer disposed over the third conductor layer. The second conductor plate layer encloses the first conductor plate layer and the fourth conductor plate layer encloses the third conductor plate layer. The device structure, when used in a back-end-of-line passive device, reduces leakage and breakdown due to corner discharge effect.