Self-Aligned Via Structure With Enlarged Sidewall Contact
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Solution Overview
Problem
Challenges exist in forming via connections in microelectronic structures due to alignment inconsistencies during removal/etching and patterning processes, leading to variations in via connections and increased resistance.
Innovation Solution
The solution involves removing the hardmask and a portion of the dielectric liner surrounding the first metal line to form a trench and extenders on the sidewalls, which are then filled with conductive metal to increase the surface contact area between the via and the metal line, thereby enhancing current flow and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional via connections are formed with standard alignment processes, then the manufacturing process is simple, but the resistance is high and current flow is limited due to small contact area
Solution Approach 1:
The via connection is extended from a simple vertical hole to include horizontal sections that wrap around the metal line and vertical extenders that reach down the sidewalls, creating a three-dimensional conductive structure. This multi-dimensional approach increases the contact surface area from a single point to an extended surface, thereby improving current flow capability while maintaining alignment tolerance.
Solution Approach 2:
The trench and extenders are formed and filled with conductive metal before final via formation, creating a pre-positioned conductive framework. This preliminary conductive structure ensures adequate contact area is established even if subsequent alignment processes have variations, thereby improving reliability against alignment precision issues.
2Reliability
If the via contact area is increased to reduce resistance, then the current flow improves, but the device complexity increases due to additional trench and extender structures
Solution Approach 1:
The trench structure and extender structures are merged into a single integrated conductive formation process. The horizontal trench sections and vertical extender sections are combined to create a unified via structure that simultaneously achieves both wide contact area for low resistance and extended sidewall coverage, reducing the need for separate structural elements.
Solution Approach 2:
The extended via structure serves multiple functions: the horizontal sections provide broad contact area for low resistance, the vertical extenders provide sidewall adhesion and alignment tolerance, and the integrated structure acts as both the via connection and the adhesion framework, eliminating the need for separate adhesion layers in some configurations.
Data Source
AI summary
A microelectronic interconnect structure that includes, a first metal line located at a first level, a second metal line located at a second level, wherein the first level and the second level are different levels, and a connecting via that connects the first metal line to the second metal line, wherein the connecting via includes a horizontal section and trench extenders, wherein the horizontal section is located on top of the first metal line, and the trench extenders extend down sidewalls of the first metal line.