3D Trench Capacitor Hybrid Filling for Thinner Dielectrics
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Solution Overview
Problem
Conventional 3D trench capacitor structures face challenges in increasing capacitance density while maintaining operating and breakdown voltages, due to mechanical and electrical stress issues caused by thick dielectric layers, which can lead to wafer deformation and premature wearout.
Innovation Solution
A 3D trench capacitor structure incorporating a hybrid filling layer composed of a conductive layer and a polymer layer, such as Parylene AF-4, which reduces mechanical stress and allows for a thinner dielectric layer, enabling increased capacitance density and operating/breakdown voltage without wafer deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the dielectric layer is increased to sustain the operating electrical field in high voltage applications, then the breakdown voltage is improved, but mechanical stress in the structure increases leading to cracks, delamination, and wafer deformation
Solution Approach 1:
The dielectric layer is segmented into multiple thinner dielectric layers separated by intermediate conductive layers. This segmentation allows each individual dielectric layer to be thinner and less stressful mechanically, while the cumulative thickness across multiple layers provides the necessary breakdown voltage. The intermediate conductive layers act as stress relief interfaces between the dielectric layers.
Solution Approach 2:
The capacitor structure uses a composite architecture combining multiple dielectric materials and conductive materials in alternating layers. This composite structure distributes mechanical stress across different material interfaces and allows optimization of each layer's thickness and material properties to balance electrical performance and mechanical integrity.
2Duration of action of stationary object
If the thickness of the dielectric layer is increased to prevent premature wear out, then the operating lifetime is improved, but electrical stress within the 3D structure increases causing faster dielectric wear out and breakdown
Solution Approach 1:
The dielectric layer is divided into multiple thinner layers with conductive intermediate layers. This segmentation reduces the electrical stress concentration that would occur in a single thick dielectric layer, particularly at singular points like sharp corners. Each thinner dielectric layer experiences lower electrical stress, preventing premature wear out and extending operating lifetime.
3Strength
If a thicker top electrode layer is used to fill the trench structure, then mechanical stress is increased, but if a thinner top electrode layer is used, electrical series resistance increases and voids remain in the structure
Solution Approach 1:
The top electrode is segmented into multiple thinner conductive layers separated by dielectric layers. This segmentation allows the total conductive material to be distributed in a way that reduces mechanical stress (thinner individual layers) while maintaining low electrical series resistance (multiple parallel conductive paths). The intermediate dielectric layers prevent void formation by providing a conformal filling structure.
Data Source
AI summary
A capacitor structure that includes a silicon substrate having a trench structure formed therein; a dielectric disposed over a surface of the trench structure, conformal to the surface of the trench structure; and a filling layer disposed over the dielectric layer and into the trench structure, the filling layer including a conductive layer and a polymer layer.