Trench Capacitor Contact Structure for Higher Density Layouts
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Solution Overview
Problem
The increase in the number of electrodes in trench capacitors to enhance capacitance density results in a larger footprint due to the need for more conductive vias, leading to decreased device density and potential fabrication issues like misalignment and shorting, which limits the number of trench capacitors that can be placed on a semiconductor substrate.
Innovation Solution
The implementation of contact structures that overlay and extend over the trenches, allowing conductive vias to be directly electrically coupled to electrodes, reducing the minimum width and length of the trench capacitor while ensuring proper via landing, thus increasing device density without compromising capacitance density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of electrodes is increased to enhance capacitance density, then capacitance density is improved, but the footprint increases due to more conductive vias required
Solution Approach 1:
The contact structure extends vertically from above the top surface of the electrodes down to contact the first electrode, utilizing the vertical dimension to provide electrical connection. This eliminates the need for lateral offset contact regions, allowing the capacitor to maintain high capacitance density without proportionally increasing the lateral footprint.
Solution Approach 2:
The contact structure merges multiple functions: it serves as both the contact region for electrical connection and as a structural element that defines the capacitor's footprint boundaries. By combining the contact function with the structural definition, the design reduces the overall footprint while maintaining necessary electrical connections.
2Quantity of substance
If the number of electrodes is increased to enhance capacitance density, then capacitance density is improved, but device density decreases due to larger footprint
Solution Approach 1:
By moving the contact region into the vertical dimension through the contact structure extending downward, the lateral space required per capacitor is reduced. This allows more capacitors to be packed into the same lateral area, increasing device density while maintaining high capacitance density through multiple electrodes.
Solution Approach 2:
The contact structure is segmented to contact specific electrodes at specific depths, allowing independent optimization of each electrode's connection. This segmentation enables compact arrangement of multiple electrodes without requiring proportional increase in lateral contact regions, thereby improving device density.
3Reliability
If contact regions are made larger to prevent misalignment and shorting, then manufacturing reliability is improved, but the footprint increases
Solution Approach 1:
The contact structure provides a vertically extended contact region that can be optimized for reliability without increasing lateral footprint. The vertical extension allows for larger effective contact area in the Z-dimension while maintaining compact lateral dimensions, thus improving manufacturing reliability without expanding the footprint.
Solution Approach 2:
The contact structure acts as an intermediary element between the conductive vias and the electrodes. It provides a controlled transition zone that facilitates reliable electrical connection while defining precise lateral boundaries, thereby ensuring manufacturing reliability without requiring enlarged lateral contact regions.
Data Source
AI summary
Various embodiments of the present disclosure are directed towards an integrated circuit (IC) including a capacitor. The capacitor is disposed over a semiconductor substrate. The capacitor includes a plurality of electrodes and a plurality of capacitor dielectric layers vertically stacked over one another. A contact structure overlies the plurality of electrodes, wherein the contact structure continuously extends from above a top surface of the plurality of electrodes to contact a first electrode in the plurality of electrodes. A first conductive via overlies and contacts the contact structure, wherein the first conductive via is directly electrically coupled to the first electrode by way of the contact structure.