Deep Trench Capacitor Structure for Deformation-Resistant Capacitance
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Solution Overview
Problem
Existing semiconductor capacitors require significant device area for high capacitance, and handling of deep trench capacitors during fabrication can cause mechanical stress and damage.
Innovation Solution
The formation of deep trench capacitors with alternating lengthwise directions and stress-relief structures around the trenches to reduce deformation and mechanical stress, using alternating metallic electrode and dielectric layers within the trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deep trench capacitors are formed with high aspect ratios to achieve high capacitance, then capacitance density is improved, but mechanical stress and deformation increase during handling
Solution Approach 1:
The deep trench capacitor structure is segmented into multiple functional regions: a first portion with electrodes extending into the trench and a second portion at the trench opening. This segmentation allows the structure to achieve high capacitance through the deep trench configuration while the separate second portion provides mechanical reinforcement at the vulnerable opening region, resolving the contradiction between capacitance density and mechanical strength.
Solution Approach 2:
The capacitor structure employs asymmetric design where the second portion at the trench opening has different geometric characteristics than the first portion. This asymmetric configuration optimizes the structure for both electrical performance (through the deep trench) and mechanical robustness (through the reinforced opening), addressing the trade-off between high aspect ratio benefits and handling vulnerabilities.
2Reliability
If alternating electrode and dielectric layers are used within deep trenches, then capacitance is increased, but structural complexity and deformation risk increase
Solution Approach 1:
The patent implements a nested structure where alternating electrode and dielectric layers are arranged concentrically within the deep trench. The electrodes and dielectric layers are positioned such that they nest within the trench volume, maximizing capacitance through the alternating layer configuration while the containing trench structure provides mechanical support that reduces deformation risk despite the increased structural complexity.
Data Source
AI summary
A semiconductor structure includes a substrate containing first-type deep trenches and second-type deep trenches. The first-type deep trenches and the second-type deep trenches have lengthwise sidewalls that laterally extend along different directions. The semiconductor structure includes a capacitor structure, which includes a layer stack containing at least three metallic electrode layers interlaced with at least two node dielectric layers. Each layer within the layer stack includes a horizontally-extending portion that overlies a top surface of the substrate and vertically-extending portions that protrude downward into a respective one of the first-type deep trenches and second-type deep trenches. The different orientations of the lengthwise directions of the deep trenches reduces deformation of the semiconductor structure. Stress-relief structures may be formed in corner regions of the capacitor structure to provide structural reinforcement.