Trench MIM Capacitor Structure With Dielectric Stress Buffering
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Solution Overview
Problem
Trench capacitors with high aspect ratios are prone to cracking and warping due to stress from sharp corners and thin layers, which is exacerbated by the reduced geometric size and increased complexity in modern semiconductor devices.
Innovation Solution
A protection dielectric layer is introduced between the semiconductor substrate and the trench MIM capacitor to act as a stress buffer, covering sharp corners and providing mechanical strength, thereby preventing metal electrode cracking and warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the trench capacitor is designed with high aspect ratio to achieve high-density layout, then the capacitance density is improved, but the metal electrodes are prone to cracking and warping due to stress concentration at sharp corners
Solution Approach 1:
A protection dielectric layer is formed over the sharp corners of the trench structure before depositing the metal electrode layers. This protection layer acts as a cushioning element that distributes stress and prevents stress concentration at the sharp corners, thereby preventing metal electrode cracking and warping while maintaining the high aspect ratio trench design for high capacitance density
Solution Approach 2:
The protection dielectric layer serves as an intermediary element between the sharp corner structure and the metal electrodes. It mediates the stress transmission by providing a compliant interface that reduces stress concentration, allowing the metal electrodes to be deposited without direct contact with the stress-concentrating sharp corners
2Volume of moving object
If the wafer thickness is minimized to reduce device size for portable applications, then the device portability is improved, but the structural strength and stress resistance are reduced
Solution Approach 1:
The protection dielectric layer is formed beforehand over the sharp corners and trench structures before subsequent processing steps. This pre-formed protection layer provides stress buffering that compensates for the reduced structural strength inherent in thinner wafers, enabling miniaturization while maintaining reliability
Solution Approach 2:
The patent employs a composite structure consisting of multiple dielectric layers with different properties - the protection dielectric layer provides mechanical strength and stress buffering, while other dielectric layers provide electrical isolation and capacitance functionality. This composite approach allows thin wafer design with maintained structural integrity
Data Source
AI summary
A semiconductor trench capacitor structure is provided. The semiconductor trench capacitor comprises a semiconductor substrate; a trench capacitor overlying the semiconductor substrate, wherein the trench capacitor comprises a plurality of trench electrodes and a plurality of capacitor dielectric layers that are alternatingly stacked over the semiconductor substrate and defines a plurality of trench segments and a plurality of pillar segments, wherein the trench electrodes and the capacitor dielectric layers are recessed into the semiconductor substrate at the trench segments, and wherein the trench segments are separated from each other by the pillar segments; and a protection dielectric layer disposed between the semiconductor substrate and the trench capacitor, wherein the protection dielectric layer has a thickness greater than thicknesses of the trench electrodes.