Metallization via alignment using sacrificial plugs

Solution Overview

Problem

In back-end-of-line metallization processes, existing methods often result in undersized or pinched-off vias and electrical connections due to misalignment of metallization contact vias with metal line cuts, leading to suboptimal electrical contacts and connections.

Innovation Solution

The method involves forming vias aligned with electrical contacts, using sacrificial via plugs to maintain via size, and positioning separators between vias to ensure self-alignment and proper electrical connections, reversing the conventional process to improve metallization layer formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional metallization processes are used to form metal line cuts, then the process is simple and straightforward, but the vias become undersized or pinched-off due to misalignment with metal line cuts

Engineering Contradiction:

Improvevia alignment and sizeVSAvoidmetallization process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent inverts the conventional metallization sequence by first forming vias aligned with electrical contacts, then forming metal lines that connect to these pre-formed vias. This reversal ensures via alignment is determined by the via formation step rather than being subject to misalignment during metal line cutting, thereby preventing undersized or pinched-off vias while maintaining process feasibility

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent performs preliminary via formation and alignment with electrical contacts before forming the metal lines. By establishing the via positions and sizes in advance, the subsequent metal line formation can be optimized to connect to these predetermined via locations, ensuring proper alignment and preventing via damage during the metallization process

Inventive Principle:

Principle #10Preliminary action

2Reliability

If vias are formed first and metal lines are formed later to connect to vias, then via alignment and size are maintained, but the metallization process becomes more complex

Engineering Contradiction:

Improveelectrical connection qualityVSAvoidmetallization process steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent inverts the conventional metallization sequence by first forming vias aligned with electrical contacts, then forming metal lines that connect to these pre-formed vias. This reversal ensures via alignment is determined by the via formation step rather than being subject to misalignment during metal line cutting, thereby preventing undersized or pinched-off vias while maintaining process feasibility

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The metallization process is segmented into distinct steps: via formation, via alignment with electrical contacts, and subsequent metal line formation. This segmentation allows each step to be optimized independently, with via formation focused on alignment and size control, and metal line formation focused on connecting to the predetermined via locations, thereby improving overall reliability

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11270935B2Metallization layer formation process

Publication Date: 2022.03.08 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A method of forming cut conductive lines is provided. The method includes forming a trough in a dielectric cover layer over a plurality of electrical contacts. The method further includes filling the trough with a planarization layer, and forming a plurality of vias in the planarization layer and the dielectric cover layer, wherein each of the plurality of vias is aligned with one of the plurality of electrical contacts. The method further includes removing the planarization layer, and forming a sacrificial via plug in each of the plurality of vias in the dielectric cover layer. The method further includes forming a fill layer in the trough, and forming a planarization layer opening through the fill layer, wherein the planarization layer opening is positioned between two adjacent sacrificial via plugs. The method further includes forming a separator in the planarization layer opening.