Capacitor Stress Relieving Layer for Trench Corner Integrity
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Solution Overview
Problem
Capacitors with trench portions face reliability issues due to internal stress concentration on the dielectric film, which can lead to damage and reduced insulation properties, especially when the substrate rigidity decreases and stress is concentrated on the corners of the trench portions.
Innovation Solution
A capacitor design featuring a stress relieving layer with a thickness smaller than the conductor layer, positioned to counteract the residual stress of the second conductor layer, and a protective film to cover the end portion of the second conductor layer and stress relieving layer, reducing stress transfer to the dielectric film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dielectric film is thickened to improve withstand voltage, then the reliability is improved, but the internal stress increases and may damage the dielectric film
Solution Approach 1:
A stress relieving layer is introduced as an intermediary between the dielectric film and the upper electrode. This layer absorbs and redistributes the internal stress, preventing stress concentration on the dielectric film while maintaining the thickened dielectric structure for high withstand voltage capability.
Solution Approach 2:
The stress relieving layer changes the stress distribution parameters within the capacitor structure. By introducing this intermediate layer with specific mechanical properties, the stress is transformed from a concentrated load on the dielectric film to a distributed load across the stress relieving layer, enabling the use of thicker dielectric films without damage.
2Quantity of substance
If a trench portion is formed to improve capacitance density, then the capacitance density is improved, but the substrate rigidity decreases and stress concentration occurs on the corners
Solution Approach 1:
The stress relieving layer acts as a mediator that compensates for the rigidity loss caused by the trench portion. It distributes the stress away from the vulnerable corner regions of the trench, preventing stress concentration while maintaining the high capacitance density achieved through the trench structure.
Solution Approach 2:
The capacitor structure becomes a composite system combining the dielectric film, stress relieving layer, and conductor layers. This composite structure leverages the mechanical properties of each layer to overcome the rigidity reduction caused by the trench, allowing the trench configuration to be maintained for high capacitance density.
3Device complexity
If the internal stress of the upper electrode is concentrated on the end portion, then the electrode structure is simplified, but the stress is transmitted to the dielectric film causing damage
Solution Approach 1:
The stress relieving layer serves as a stress-distributing intermediary between the upper electrode and the dielectric film. It receives the concentrated stress from the electrode end portion and redistributes it across a wider area, preventing direct transmission of high stress to the dielectric film and avoiding damage.
Solution Approach 2:
The stress relieving layer converts the harmful concentrated stress from the electrode into a beneficial distributed stress pattern. By intentionally designing this intermediate structure, the stress concentration that would otherwise damage the dielectric film is transformed into a controlled stress distribution that enhances overall device reliability.
Data Source
AI summary
A capacitor is provided that includes a base having a first main surface and a second main surface opposing each other with a trench formed on a side of the first main surface (110A. Moreover, a dielectric film is disposed in a region that includes an inside of the trench on the side of the first main surface of the base; a conductor film is provided that includes a first conductor layer disposed on the dielectric film, which is the region including the inside of the trench and a second conductor layer disposed on the first conductor layer; and a stress relieving portion is provided in contact with at least a part of the end of the first conductor layer. Moreover, a thickness of the stress relieving portion is smaller than a thickness of the conductor film, outside the trench portion of the first main surface of the base.