Through-Layer Skip Via Structure Without Intermediary Line Breaks
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Solution Overview
Problem
Conventional semiconductor devices require breaking metal lines in intermediary metal layers to form skip vias, leading to extensive tapers and increased shorting risks, which is inefficient and unreliable.
Innovation Solution
A through layer skip via is formed using a damascene metal portion and a subtractive metal portion, encapsulated by a dielectric spacer, allowing the via to traverse multiple metal layers without breaking the intermediary metal lines, thus reducing shorting risks and eliminating taper issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If metal lines in the intermediary metal layer are broken to form a gap for the skip via, then the skip via can pass through the intermediary level, but the manufacturing complexity increases and the reliability decreases due to increased shorting risks
Solution Approach 1:
The skip via structure is divided into two separate portions: a subtractive metal portion that extends through the intermediary metal layer, and a damascene metal portion that connects to it. This segmentation allows each portion to be formed using optimized processes, with the subtractive portion providing mechanical strength and the damascene portion ensuring reliable electrical connection, thereby reducing shorting risks while maintaining manufacturability.
Solution Approach 2:
A dielectric spacer is introduced as an intermediary element that surrounds the subtractive metal portion within the intermediary metal layer. This spacer acts as a protective barrier that electrically isolates the subtractive metal portion from the broken metal lines, preventing short circuits while allowing the skip via to traverse the intermediary layer effectively.
2Length of moving object
If the skip via is formed by extensive etching through multiple metal layers, then the via can traverse deep structures, but the via opening becomes extremely narrow with extensive taper
Solution Approach 1:
The via formation process is segmented into two distinct portions: the subtractive metal portion formed by etching through the intermediary layer, and the damascene metal portion formed by depositing conductive material into a patterned opening. This segmentation allows the upper damascene portion to be formed with precise width control independent of the lower subtractive portion, eliminating the extensive taper problem while maintaining the required via depth.
Solution Approach 2:
The subtractive metal portion is formed first by etching through the intermediary metal layer to create a preliminary structure. Then, the dielectric spacer is deposited around this preliminary structure, and finally, the damascene metal portion is formed on top. This preliminary action allows subsequent steps to build upon a stable foundation, enabling precise control of the upper via opening width regardless of the lower portion's dimensions.
3Ease of operation
If metal lines are broken and recessed away from the skip via, then sufficient space is created for the via to pass through, but the device complexity increases
Solution Approach 1:
Instead of breaking and recessing metal lines to create space, the invention extracts the problematic metal lines from the intermediary layer entirely by removing them during the formation of the subtractive metal portion. The dielectric spacer then surrounds this extracted structure, providing the necessary space for the skip via to pass through without requiring complex metal line modifications.
Data Source
AI summary
A semiconductor device includes a through layer skip via that traverses an intermediary metal layer. The through layer skip via has a damascene metal portion and a subtractive metal portion. A dielectric spacer is disposed within a thickness of the intermediary metal layer and surrounds a top portion of the subtractive metal portion.