Trench Capacitor Edge Patterning for Thermal Stress Relief
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Solution Overview
Problem
Trench capacitors in integrated passive devices (IPDs) face challenges due to differing coefficients of thermal expansion between the substrate, capacitor dielectric layers, and capacitor electrodes, leading to stress-induced bending of the substrate and potential trench burnout, especially at the edges.
Innovation Solution
The trench capacitor design incorporates edge in-trench capacitor segments with greater widths and/or increased pitch at the edges, which provides larger gaps for stress absorption and increased substrate rigidity, reducing the likelihood of substrate bending and trench burnout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform trench width is used throughout the capacitor structure, then manufacturing simplicity is maintained, but stress concentration at edges causes substrate bending and trench burnout
Solution Approach 1:
The patent applies local quality by varying the trench width across different regions of the capacitor structure. Edge trenches have greater width than center trenches, creating different mechanical properties at different locations. This local variation in trench geometry allows the structure to better distribute and absorb thermal expansion stress, preventing substrate bending and trench burnout while maintaining overall structural integrity.
2Productivity
If tight pitch between trenches is used, then capacitor density is improved, but stress absorption capability is reduced leading to increased burnout risk
Solution Approach 1:
The patent implements local quality by applying different pitch values to different regions of the capacitor. Edge regions have greater pitch between trenches compared to center regions, allowing sufficient stress absorption capability at edges where thermal stress is highest. This regional differentiation maintains high overall capacitor density while ensuring reliability at critical stress points.
3Reliability
If edge trenches have greater width, then stress absorption is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the capacitor structure into distinct edge and center regions with different trench characteristics. This segmentation allows each region to be optimized independently for its specific functional requirements - edge trenches for stress absorption and center trenches for density - while using standard manufacturing processes to create the varied geometry.
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
This design effectively mitigates stress-related issues, enhancing the yield and reliability of bulk manufacturing by reducing substrate bending and trench burnout, particularly at the edges of the trench capacitor.
Implementation Method 1
edge in-trench capacitor segments with greater widths and/or increased pitch at the edges, which provides larger gaps for stress absorption
Implementation Method 2
increased pitch at the edges, which provides larger gaps for stress absorption and increased substrate rigidity
Data Source
AI summary
Various embodiments of the present disclosure are directed towards a trench capacitor with a trench pattern for yield improvement. The trench capacitor is on a substrate and comprises a plurality of capacitor segments. The capacitor segments extend into the substrate according to the trench pattern and are spaced with a pitch on an axis. The plurality of capacitor segments comprises an edge capacitor segment at an edge of the trench capacitor and a center capacitor segment at a center of the trench capacitor. The edge capacitor segment has a greater width than the center capacitor segment and/or the pitch is greater at the edge capacitor segment than at the center capacitor segment. The greater width may facilitate stress absorption and the greater pitch may increase substrate rigidity at the edge of the trench capacitor where thermal expansion stress is greatest, thereby reducing substrate bending and trench burnout for yield improvements.