Trench Capacitor Extended Dielectric Layer
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Solution Overview
Problem
As electronic devices become smaller and more complex, trench capacitors face challenges in maintaining high capacitance while avoiding shorting between capacitor plates, particularly due to non-uniformity in etch recess lengths across the wafer, leading to variability in capacitance.
Innovation Solution
A trench capacitor design that uses additional chemical mechanical polishing (CMP) processes and sacrificial material to form unique layer structures, where the capacitor dielectric layer extends above the trench, providing a wider contact width and preventing shorting, and a conductive fill material fills the trench, allowing for a co-planar top surface with the capacitor dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the trench width is reduced to maximize capacitance density, then the capacitance per unit area increases, but the risk of shorting between capacitor plates increases due to non-uniform etch recess lengths
Solution Approach 1:
The capacitor dielectric layer is extended from the traditional bottom-only configuration to wrap around the sidewalls of the trench and protrude above the interlayer dielectric surface. This three-dimensional extension adds vertical and lateral dimensions to the dielectric barrier, preventing shorting while maintaining narrow trench width for high capacitance density.
Solution Approach 2:
The capacitor dielectric layer is deposited to extend above the interlayer dielectric surface before subsequent processing steps. This preliminary extension creates a protective barrier that prevents shorting between the lower electrode and upper contact, ensuring reliability before final electrode formation.
2Reliability
If additional CMP processes and sacrificial material are used to extend the dielectric layer, then shorting is prevented and capacitance variability is reduced, but the manufacturing complexity increases
Solution Approach 1:
A sacrificial material layer is introduced as an intermediary element during fabrication. This sacrificial layer is deposited, patterned, and removed in controlled steps to enable the capacitor dielectric layer to extend above the interlayer dielectric surface without directly complicating the main capacitor formation process.
Solution Approach 2:
The fabrication process is segmented into distinct stages: depositing the capacitor dielectric layer, forming the sacrificial material, selective removal of sacrificial material, and final electrode formation. This segmentation allows each step to be optimized independently, managing overall process complexity while achieving the extended dielectric structure.
3Manufacturing precision
If the contact width is increased to improve manufacturing tolerance, then alignment variability is reduced, but the area available for capacitance formation decreases
Solution Approach 1:
The capacitor dielectric layer protrudes above the interlayer dielectric surface, creating a vertical barrier that allows the upper contact to be wider without increasing lateral overlap with the lower electrode. This vertical extension decouples contact width from alignment precision requirements, enabling wider contacts for manufacturing tolerance while preserving capacitance area.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively reduces shorting issues and variability in capacitance across the wafer, enabling the creation of smaller, more robust energy storage components with consistent performance.
Implementation Method 1
additional chemical mechanical polishing (CMP) processes
Implementation Method 2
the capacitor dielectric layer effectively provides the benefit of allowing for a top contact having a wider width since the capacitor dielectric layer protects the bottom electrode from contacting the top contact and shorting the capacitor
Data Source
AI summary
An improved trench capacitor structure is disclosed that allows for the formation of narrower capacitors. An example capacitor structure includes a first conductive layer on the sidewalls of an opening through a thickness of a dielectric layer, a capacitor dielectric layer on the first conductive layer, a second conductive layer on the capacitor dielectric layer, and a conductive fill material on the second conductive layer. The capacitor dielectric layer laterally extends above the opening and along a top surface of the dielectric layer, and the conductive fill material fills a remaining portion of the opening.