Self-Aligned Supervia Structure for BEOL Metal Fill and Alignment

Solution Overview

Problem

The formation of supervias in BEOL interconnect structures is challenging due to high aspect ratio via holes, which can lead to misalignment and insufficient metal fill.

Innovation Solution

A method involving the use of a wide-width trench with a lower aspect ratio to form via metal, combined with additional photolithography masking processes, enables self-aligned via structures and improved metal fill characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a supervia hole with higher aspect ratio is used, then the supervia can be formed to connect through multiple inter-metal layers, but misalignment with lower metal pattern and insufficient metal-fill occur

Engineering Contradiction:

Improvesupervia depthVSAvoidalignment precision

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The supervia formation process is segmented into multiple steps: first forming a wide trench with lower aspect ratio, then dividing it into multiple supervia holes. This segmentation allows each individual supervia to have better metal fill while the collective structure achieves the required depth for connecting through multiple inter-metal layers.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A wide trench is formed preliminarily before creating the final supervia structure. This preliminary wide trench has lower aspect ratio that facilitates better metal deposition, and subsequent processing divides it into the final supervia configuration, ensuring both adequate depth and sufficient metal fill.

Inventive Principle:

Principle #10Preliminary action

2Length of moving object

If a supervia hole with higher aspect ratio is used, then the supervia can be formed to connect through multiple inter-metal layers, but insufficient metal-fill in the supervia hole occurs

Engineering Contradiction:

Improvesupervia depthVSAvoidmetal-fill

Core Design Contradiction:

Length of moving objectVSQuantity of substance

Solution Approach 1:

The supervia formation process is segmented into multiple steps: first forming a wide trench with lower aspect ratio, then dividing it into multiple supervia holes. This segmentation allows each individual supervia to have better metal fill while the collective structure achieves the required depth for connecting through multiple inter-metal layers.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A wide trench is formed preliminarily before creating the final supervia structure. This preliminary wide trench has lower aspect ratio that facilitates better metal deposition, and subsequent processing divides it into the final supervia configuration, ensuring both adequate depth and sufficient metal fill.

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If a wide-width trench with lower aspect ratio is used, then metal fill is improved, but additional photolithography masking process is required

Engineering Contradiction:

Improvemetal-fillVSAvoidprocess complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The formation of the wide trench and the subsequent division into supervia holes are merged into a single integrated process flow. The additional photolithography masking step is combined with the existing supervia formation process, allowing the wide trench to serve dual purposes: providing good metal fill characteristics and enabling precise supervia positioning through self-alignment.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The wide trench structure serves multiple functions: it provides the necessary depth for supervia connection, ensures adequate metal fill due to its lower aspect ratio, and acts as a self-aligned mask for defining the final supervia positions, eliminating the need for separate alignment processes.

Inventive Principle:

Principle #25Self-service

Data Source

PatentEP3979303B1Via structure including self-aligned supervia and method for manufacturing the same

Publication Date: 2025.05.28 SAMSUNG ELECTRONICS CO LTD

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AI summary

A semiconductor device structure includes: at least one inter-metal layer stacked in a vertical direction; and a 1st via structure (204S1) penetrating the at least one inter-metal layer, wherein, in the at least one inter-metal layer, a 1st vertical side of the 1st via structure (204S1) does not contact a barrier metal pattern (205S) while a 2nd vertical side of the 1st via structure (204S1) opposite to the 1st vertical side of the 1st via structure (204S1) contacts the barrier metal pattern (205S).