Nested BEOL MIM Capacitor Structure for Leakage and TDDB Control
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Solution Overview
Problem
Existing Metal-Insulator-Metal (MIM) capacitors in semiconductor integrated circuits face issues such as conductor plate layer patterning damaging insulator layers, leading to leakage paths and reduced time-dependent-dielectric-breakdown (TDDB) reliability due to uneven conductor plate dimensions and localized electric field intensification at corners.
Innovation Solution
Implementing an odd-number-layer-enclosure and even-number-layer-enclosure configurations for MIM capacitors, where odd-numbered and even-numbered conductor plate layers enclose one another, minimizing leakage and enhancing TDDB reliability by optimizing conductor plate layer dimensions and spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conductor plate layers are patterned to different dimensions, then capacitor design flexibility is improved, but insulator layer damage occurs leading to leakage paths
Solution Approach 1:
The patent implements an enclosure configuration where odd-numbered conductor plate layers are nested within even-numbered conductor plate layers, with each layer enclosing the previous one. This nested structure allows different conductor plate dimensions and areas while maintaining proper insulation, as each conductor plate is completely enclosed by the next layer, preventing leakage paths even when dimensions vary.
Solution Approach 2:
The patent transitions from considering only planar dimensions to incorporating vertical layering as an additional dimension. By stacking conductor plates in multiple layers with alternating enclosure patterns, the design achieves flexibility in planar dimensions while maintaining reliability through the vertical enclosure relationship, effectively solving the contradiction between design freedom and leakage prevention.
2Adaptability or versatility
If conductor plate dimensions are made uneven, then capacitor functionality is improved, but localized electric field intensification occurs at corners reducing TDDB reliability
Solution Approach 1:
The enclosure configuration where each conductor plate layer is completely enclosed by the next layer eliminates exposed corners and edges that would concentrate electric fields. The nested structure ensures that electric field lines are evenly distributed throughout the insulator layers, preventing localized intensification while still allowing different plate dimensions for functional requirements.
Solution Approach 2:
The patent applies different dimensional characteristics to different layers - odd-numbered layers have one set of dimensions while even-numbered layers have different dimensions. This local differentiation allows functional optimization for specific capacitor requirements while the overall enclosure structure maintains uniform electric field distribution and prevents corner discharge issues.
3Area of stationary object
If MIM capacitors are moved to back-end-of-line structures, then large surface area requirements are met, but processing complexity increases
Solution Approach 1:
The patent divides the capacitor structure into multiple discrete conductor plate layers and insulator layers, with each layer being a separate processing element. This segmentation allows each layer to be formed using standard back-end-of-line processing techniques, making the overall complex structure achievable through sequential application of simpler, well-established manufacturing steps.
Solution Approach 2:
The nested enclosure configuration provides a systematic pattern for building the multi-layer structure, where each layer follows a predictable formation sequence. This regular nested pattern simplifies the processing complexity by providing a repeatable manufacturing approach, even though the overall device has large surface area and multiple layers.
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.