Rotationally Symmetric Trench Capacitor Layout for Low Warpage
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Solution Overview
Problem
Trench capacitors in semiconductor integrated circuits experience warpage and cracking due to unbalanced stress caused by mirror symmetry in two-dimensional trench arrays, which worsens with increasing density.
Innovation Solution
Implementing a rotationally symmetric layout of capacitors and incorporating air gaps within the trench structures to alleviate stress, using a method that includes depositing dielectric and conducting layers with controlled thicknesses and planarization processes to form capacitor structures with reduced warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mirror symmetry is used in two-dimensional trench arrays, then manufacturing simplicity is maintained, but warpage and cracking occur due to unbalanced stress
Solution Approach 1:
The patent applies asymmetry by intentionally designing trench arrays with non-uniform patterns, including varying trench densities, depths, and orientations in different regions. This asymmetric configuration balances stress distribution across the substrate, preventing warpage and cracking while maintaining manufacturing feasibility through standardized fabrication processes.
2Quantity of substance
If trench density is increased to achieve high power density, then capacitor capacity is improved, but stress concentration worsens leading to more warpage and cracking
Solution Approach 1:
The patent implements local quality by varying trench characteristics across different regions of the array. High-density regions provide greater capacitor capacity where needed, while low-density regions with larger spacing reduce stress concentration. The trench depth, width, and orientation are locally optimized to balance capacity requirements with stress management in each specific area.
Solution Approach 2:
The trench array is segmented into multiple zones with different density levels, depths, and orientations. This segmentation allows the structure to achieve high overall capacity while distributing stress across multiple lower-density regions, preventing stress concentration that would lead to warpage and cracking.
3Manufacturing precision
If uniform trench depth and orientation are used, then manufacturing precision is simplified, but stress lines become concentrated causing warpage
Solution Approach 1:
The patent introduces asymmetry in trench orientation and depth across different regions of the array. By varying the angular orientation and depth of trenches in a non-uniform pattern, stress lines are effectively broken and redistributed, preventing the concentration that causes warpage while maintaining manufacturing precision through controlled fabrication parameters.
Data Source
AI summary
A capacitor structure and method of forming the capacitor structure is provided, including a providing a doped region of a substrate having a two-dimensional trench array with a plurality of segments defined therein. Each of the plurality of segments has an array of a plurality of recesses extending along the substrate, where the plurality of segments are rotationally symmetric about a center of the two-dimensional trench array. A first conducting layer is presented over the surface and a bottom and sidewalls of the recesses and is insulated from the substrate by a first dielectric layer. A second conducting layer is presented over the first conducting layer and is insulated by a second dielectric layer. First and second contacts respectively connect to an exposed top surface of the first conducting layer and second conducting layer. A third contact connects to the substrate within a local region to the capacitor structure.