MIM Capacitor Contact Area via Isotropic Etching
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Solution Overview
Problem
Current semiconductor device fabrication techniques for metal-insulator-metal (MIM) capacitors in back-end-of-line (BEOL) interconnect structures face challenges in optimizing capacitance and contact resistance due to limited electrode contact areas and dielectric layer configurations.
Innovation Solution
The structure and method involve a MIM capacitor with three electrodes and a conductive via extending through a via opening, where isotropic etching is used to expose horizontal surfaces on the electrodes, increasing the contact area between the conductive via and the electrodes, thereby enhancing the contact resistance and capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MIM capacitor structures with limited electrode contact areas are used, then device complexity is reduced, but contact resistance increases and capacitance is limited
Solution Approach 1:
The electrode contact structure is segmented into multiple regions: a first contact region on the top surface, a second contact region on the bottom surface, and a third contact region on the side surface. This segmentation allows the conductive via to contact the electrode at multiple discrete locations, distributing the contact interface and reducing overall contact resistance while maintaining a manageable structural complexity through systematic division of the contact function.
Solution Approach 2:
The invention transitions from conventional two-dimensional top-down contact to three-dimensional multi-surface contact by utilizing the side surface of the electrode as an additional contact dimension. The conductive via wraps around or contacts the electrode laterally, adding a vertical/dimensional component to the contact geometry that increases effective contact area without proportionally increasing planar footprint or device complexity.
2Reliability
If conventional via openings with limited contact area are used, then manufacturing precision requirements are reduced, but capacitance is limited
Solution Approach 1:
The conductive via structure is designed to nest around the electrode, with the via opening configured to contact the electrode on multiple surfaces including the side surface. This nested geometry allows the via to envelop or closely conform to the electrode structure, maximizing contact area within the constraints of the via opening dimensions and reducing sensitivity to precise alignment requirements during manufacturing.
Solution Approach 2:
The via opening is designed with non-uniform characteristics, being wider or having different dimensions at different heights to accommodate the multi-surface contact requirement. This local variation in via geometry allows optimized contact at each surface (top, bottom, side) while maintaining manufacturability, as each local region can be tailored to its specific functional requirement rather than requiring uniform high precision throughout.
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 configuration increases the contact area between the conductive via and the electrodes, reducing contact resistance and potentially improving capacitance by allowing for a more effective integration of MIM capacitors in BEOL interconnect structures.
Implementation Method 1
etching a dielectric layer relative to the first electrode with an isotropic etching process to expose a surface on the first electrode inside the via opening
Data Source
AI summary
Structures that include a metal-insulator-metal (MIM) capacitor and methods for fabricating a structure that includes a MIM capacitor. The MIM capacitor includes a first electrode, a second electrode, and a third electrode. A conductive via is arranged in a via opening extending in a vertical direction through at least the first electrode. The first electrode has a surface arranged inside the via opening in a plane transverse to the vertical direction, and the conductive via contacts the first electrode over an area of the surface.