3D Silicon Capacitor Structure With Undercuts for Higher Density
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Solution Overview
Problem
There is a growing demand for capacitors with higher density as increasingly dense circuitry is developed, but existing technologies have limitations in achieving high capacitance density.
Innovation Solution
A pillar or trench structure with vertical portions and indented cavities is used, featuring multiple conductive contact layers and high-k dielectric layers within the undercuts and vertical portions, which increases capacitance density through directional and isotropic etching techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional capacitor structures are used, then manufacturing is simpler, but capacitance density is lower
Solution Approach 1:
The patent transitions from planar capacitor structures to three-dimensional pillar structures with vertical portions and indented cavities. This dimensional change allows multiple conductive layers to be stacked vertically, significantly increasing capacitance density by utilizing the third dimension (height) rather than only horizontal expansion.
Solution Approach 2:
The patent implements nested conductive layers within the pillar structure, where multiple conductive contact layers are positioned at different heights and depths within the same vertical footprint. The indented cavities contain additional conductive layers that are nested within the overall pillar structure, effectively packing more capacitive elements into a compact volume.
2Quantity of substance
If indented cavities are added to increase density, then capacitance density improves, but manufacturing complexity increases
Solution Approach 1:
The etching process is segmented into distinct directional steps: first vertical etching to create the pillar structure, then isotropic etching to form indented cavities. This segmentation allows each etching step to be optimized independently, using appropriate etchants and process parameters for each specific geometric feature, thereby managing manufacturing complexity.
Solution Approach 2:
The patent employs preliminary protective films deposited on specific surfaces before etching. These films are applied in advance to protect certain areas from isotropic etching, enabling precise formation of indented cavities. The protective films are later removed selectively, allowing controlled creation of the complex cavity geometry without requiring overly complex real-time etching control.
Data Source
AI summary
A pillar or trench structure in a substrate includes vertical portions and one or more indented cavities in a sidewall between the vertical portions. The indented cavities are partial undercuts substantially traverse to the vertical portions pillar structure, or separate undercuts attached to an anchor. A higher capacitance density is achieved through the layering of multiple conductive contact layers and insulating layers in the undercuts and the vertical portions of the pillar or trench structure.