MIM Capacitor Contact Structure for Lower Via Resistance
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Solution Overview
Problem
Conventional Metal-Insulator-Metal (MIM) capacitors face high contact resistance due to small contact areas between vias and metal pads, which are typically thin, limiting their performance in functional circuits.
Innovation Solution
The formation of conductive plugs that not only contact the edges of metal pads but also the top surfaces, increasing the contact area and reducing resistance, thereby improving the electrical connection between the vias and metal pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional vias are used with edge-only contact to metal pads, then the fabrication process is simple, but the contact area is small and contact resistance is high
Solution Approach 1:
The via structure is extended from a simple vertical cylinder to include an upper portion that protrudes laterally beyond the lower portion. This dimensional change creates additional contact areas with the metal pad, transforming the contact geometry from edge-only to include both edge and top surface contact, thereby reducing contact resistance without complicating the fabrication process
Solution Approach 2:
The via upper portion is formed to protrude beyond the lower portion before final metallization is completed. This preliminary geometric configuration ensures that when metal is deposited, the via structure already provides maximized contact area with the metal pad, preparing the structure in advance for optimal electrical connection
Data Source
AI summary
A method includes forming a first electrode layer having a first opening, with the first opening having a first lateral dimension, forming a first capacitor insulator over the first electrode layer, and forming a second electrode layer over the first capacitor insulator, with the second electrode layer having a second opening. The first opening is directly underlying the second opening. The second opening has a second lateral dimension greater than the first lateral dimension. The method further includes depositing a dielectric layer over the second electrode layer, and forming a contact opening, which comprises a first portion including the first opening, and a second portion including the second opening. A conductive plug is formed in the contact opening.